Final Report

Auditing of water use on construction sites - Phase I & Phase II

This report summarises the findings from an evaluation of water use on constructions sites. These findings include the results of a limited water audit programme which comprised a snapshot one day audit of nine construction sites (Phase I), and a subsequent water audit programme which comprised an audit of three construction sites over an extended period (Phase II), in the United Kingdom. Project Code: WAS908-004 & HWL101-504

Research date: February 2011 to April 2012

Date: December 2012

WRAP’s vision is a world without waste, where resources are used sustainably. We work with businesses and individuals to help them reap the benefits of reducing waste, develop sustainable products and use resources in an efficient way. Find out more at www.wrap.org.uk

Written by: Derek J. McNab, Michael Lynch and Paul Young of Mabbett & Associates Ltd

Front cover photography: [Rain gun dust suppression operating from the back of a water bowser.]

WRAP and Mabbett & Associates Ltd believe the content of this report to be correct as at the date of writing. However, factors such as prices, levels of recycled content and

regulatory requirements are subject to change and users of the report should check with their suppliers to confirm the current situation. In addition, care should be taken in using any of the cost information provided as it is based upon numerous project-specific assumptions (such as scale, location, tender context, etc.). The report does not claim to be exhaustive, nor does it claim to cover all relevant products and specifications available on the market. While steps have been taken to ensure

accuracy, WRAP cannot accept responsibility or be held liable to any person for any loss or damage arising out of or in connection with this information being inaccurate, incomplete or misleading. It is the responsibility of the potential user of a material or product to consult with the supplier or manufacturer and ascertain whether a particular product will satisfy their specific requirements. The listing or featuring of a particular product or company does not constitute an endorsement by WRAP and WRAP cannot guarantee the performance

of individual products or materials. This material is copyrighted. It may be reproduced free of charge subject to the material being accurate and not used in a misleading context. The source of the material must be identified and the copyright status acknowledged. This material must not be used to endorse or used to suggest WRAP’s endorsement of a commercial product or service. For more detail, please refer to WRAP’s Terms & Conditions on its web site: www.wrap.org.uk

1

Executive Summary Within the construction sector, the joint government and industry Strategy for Sustainable Construction published in 2008, highlighted the issue of water use by construction activities and included a number of targets pertaining to more efficient use of water. One such target identified water usage on construction sites as a priority area. The target, identified by the industry itself, is that: “By 2012, water use in the manufacturing and construction phase to be reduced by 20% compared to 2008 usage”. The body responsible for delivering the water target is the Strategic Forum for Construction (SFfC) Water Subgroup who has developed an Action Plan to work towards this target. WRAP (Waste and Resources Action Programme) is a representative on the SFfC Water Subgroup. The SFfC Water Subgroup developed an Action Plan to assist the construction industry in reducing the volume of water used on construction sites. The Action Plan highlights two major themes. Firstly, the need to gather information on where water is used, and where water is wasted on construction sites, along with identification of suitable water conservation measures. Secondly, the Action Plan aims to improve site water use behaviour through embedding principles of water conservation throughout the construction process. A 2008

baseline figure of 148 m3 per £million contractors output at constant (2005) prices will be used to assess any improvement. Mabbett & Associates Ltd (Mabbett) were commissioned by WRAP on behalf of the Subgroup to deliver a limited programme of audit work before the end of March 2011 to support the Action Plan with the following objectives:

To develop robust primary data quantifying where water is wasted and the associated water using processes on

construction sites through a series of site audits across a range of sites.

To establish an evidence base of good practice for reduction of water use in the construction process.

This initial audit work is hereafter referred to as Phase I. WRAP proposed a series of audits be carried out using a predefined methodology (and further refined by Mabbett to take account of the project time limitations) in delivering the

required Phase I project outputs between 15 February 2011 and 31 March 2011; a total of 6 weeks. In total, nine (9)

sites were audited in this Phase I of work.

Mabbett were subsequently commissioned by WRAP to deliver a further programme of audit work over an extended period, hereafter referred to as Phase II. The objective of this work was to further develop the findings from Phase I, to include:

Longer term monitoring;

Capturing the outstanding high priority activities (e.g. hydro-demolition); and

Better quantifying the savings potential of conservation measures.

Three (3) sites were audited between November 2011 - April 2012. The SFfC Water Subgroup has identified those activities expected to be ‘high priority’ i.e. the activities expected to provide the greatest opportunities for water efficiency savings. These are: Table 1: High Priority Activities

Water Using Activity High Priority Activity

Dust Suppression General, site roads, wheel washes

Hydro-demolition with high pressure water

Cleaning

Ready mixed concrete wagons

Site/general cleaning

Specialist/high pressure cleaning

Commissioning & Test Building plant/services

These activities were the primary focus of the auditing programme, though information on those activities considered low priority was also gathered/collected.

2

The following points summarise some of the main findings from the project:

There is little consistency throughout the construction sector in relation to water management. Some sites had metered supplies and paid for their water regularly, based on volumetric consumption, whilst other sites were not even registered with the local water provider (i.e. were not paying for water). It is suggested that if each construction company paid for their water based on volumetric consumption, the additional focus this would provide alone may achieve significant water savings.

Monitoring (and targeting) of water consumption data needs to improve if the construction sector wants to achieve a significant reduction in their water consumption - even some of the sites with water meters in place were unaware of how much water they were using.

Improved housekeeping (e.g. reporting/repairing leaks, etc) should provide a simple method of reducing water consumption.

As expected, dust suppression and cleaning were identified as high priority areas for achieving significant water savings. Possible methods of achieving these savings are discussed in the main body of the report.

Additional investigation into commissioning and testing water consumption is required before further comment can be made with respect to potential improvements in this area, as this was only assessed at one site.

All activities initially deemed low priority were generally observed to be so, with the exception of domestic and

welfare water consumption. Whilst this area may generally be perceived as a low water use, it is the one constant during all phases of a construction project, and findings to date suggest it will account for a significant portion of a site’s total water consumption. It is suggested this is henceforth considered a high priority area.

Water saving opportunities were identified at all audited sites, with savings typically ranging from 13% - 24%, and as high as 40% - 83% where significant leaks were observed.

Based on the findings to date, achieving the SFfC Water Subgroup’s target of a 20% reduction in the water consumption of construction sites may be achievable.

Some of the main opportunities for improving water efficiency are discussed in greater detail below: Following the auditing programme, it became clear that the one area where all sites could make improvements to water efficiency was domestic and welfare water consumption. This water requirement is unique at construction sites, in that it is present at each site for (generally) the full project duration. As such, it seems to account for a significant portion of a site’s water consumption, and represents an excellent (and relatively simple) opportunity for improving water efficiency in the construction sector. Another area where the majority of sites could improve was monitoring and targeting of water consumption. Where a site is unaware of how much water they are consuming (this was particularly prevalent at sites which did not pay for their water consumption on a variable basis), they are less likely to make improvements in this area. As such, ensuring each site is aware of exactly how much they are using (at a minimum) is likely to help promote a more water efficiency culture. At a number of sites, hoses without trigger-operated spray gun control were in operation. Generally, this is considered poor practice, and can lead to instances where hoses are left operational whilst not in use. It should prove a relatively simple (and inexpensive) matter to retro-fit spray guns to these hoses to eliminate this risk. Leaks were observed (or suspected) at multiple sites, some of which accounted for a significant portion of a site’s water consumption. In addition, unrepaired leaks can act to detract from a water efficient culture, and may lead to additional water efficiencies elsewhere on site. As such, site management should ensure that a formal system is in place for

checking/reporting/repairing leaks, on a regular basis. The dust suppression systems which were observed (or reported) were water inefficient in a number of instances, and significant improvements could be made in this area. When operational, these systems will generally account for a significant portion of a site’s water consumption, and as such water savings could be high. However, further work is required to more accurately quantify the mains water requirement associated with these activities. When operational, hydro-demolition is likely to be one of the largest water consuming activities at any construction site, and as such it is recommended that this water using activity is quantified where possible. However, it is suspected that the opportunity for water savings is relatively low. The first revision of this report was published in July 2011, and incorporated the findings from Phase I only. The second revision of this report, published in August 2012, includes both the results of Phase I and Phase II.

3

Contents 1.0 Introduction 6

2.0 Sites 8

3.0 Audit Methodology 10

3.1 Introduction 10

3.2 Validity & Limitations of the Collected Data 10

3.3 Overview of Mabbett Applied Methodology 11

3.3.1 Phase 1 11

3.3.2 Phase II 12

4.0 Water Saving Devices & Practices: General Activities 13

4.1 Water Supply 13

4.2 Housekeeping 13

4.3 Monitoring and Targeting 14

4.3.1 Water Quantification 14

4.3.2 Meter Readings 15

4.3.3 KPIs 15

4.3.4 Targeting 15

4.4 Other Business Benefits 15

5.0 Water Saving Devices & Practices: High Priority Activities 16

5.1 Dust Suppression (General) 16

5.1.1 Rain Guns & Manual Hosing 17

5.1.2 Fan Misting Systems 17

5.2 Dust Suppression (Site Roads) 18

5.2.1 Dust Suppression Vehicles (Splash Plate Operation) 19

5.2.2 Dust Suppression Vehicles (Hydraulic Spinning System) 19

5.2.3 Road Sweepers 20

5.2.4 Hard-standing Ground 21

5.3 Dust Suppression (Wheel Wash) 21

5.3.1 High Pressure Washer (Wheel Wash) 22

5.3.2 Drive-on Wheel Wash 22

5.4 Dust Suppression (Hydro-demolition with high pressure water) 24

5.5 Chemical Additives 25

5.6 Control Systems 25

5.7 Cleaning (Ready Mixed Concrete Wagons) 26

5.8 Cleaning (Site/General Cleaning/Specialist/High Pressure) 29

5.8.1 Auto-isolation of Flow 29

5.8.2 High Pressure (Low Flow) Washers 30

5.8.3 Consult the Marketplace 31

5.9 Commissioning & Testing 31

6.0 Water Saving Devices & Practices: Low Priority Activities 32

6.1 Site Cabins/Temporary Accommodation 32

6.1.1 Wash Hand Basins 33

6.1.2 Sinks 34

6.1.3 Toilet Cisterns 34

6.1.4 Urinal Cisterns 34

6.1.5 Showers 35

6.1.6 Canteens 35

6.2 General Site Activities 35

6.2.1 Tool Washing 35

6.2.2 Rinsing 36

6.3 Wet Trades 36

6.3.1 Concreting & Bentonite Mixing 36

6.3.2 Intermediate Vessels 37

6.3.3 Mortar 37

4

Contents

6.0 Water Saving Devices & Practices: Low Priority Activities (Cont'd)

6.4 Groundworks 38

6.4.1 Grouting 38

6.4.2 Drilling/Piling 38

6.5 Cleaning 38

7.0 Further Work Required 39

7.1 High Priority Activity Auditing 39

7.2 Auditing Methodology 39

7.3 Matrix of Sites for Water Audits 39

Appendix 1: Site 1: Leisure (Sports Hall/Centre) Venue 40

Appendix 2: Site 2: Leisure (Theatre) Venue 46

Appendix 3: Site 3: Civil Engineering (Road) Site 53

Appendix 4: Site 4: Commercial Retail (Department Store) Site 63

Appendix 5: Site 5: Leisure (Sports Hall/Centre) Venue 69

Appendix 6: Site 6: Civil Engineering (Road) Site 78

Appendix 7: Site 7: Education (High School) Site 86

Appendix 8: Site 8: University (Laboratory) Building 93

Appendix 9: Site 9: Leisure (Theatre) Venue 99

Appendix 10: Water Audit Methodology 104

Appendix 11: Site 10: Commercial & Residential (Laboratory) Development 115

Appendix 12: Site 11: Civil Engineering (Railway) Site 120

Appendix 13: Site 12: Civil Engineering (Airport) Site 128

5

Acknowledgements The Waste and Resource Action Programme (WRAP) has commissioned Mabbett & Associates Ltd (Mabbett) to prepare this ‘auditing of water use on construction sites’ report.

This report is subject to and issued in connection with the Mabbett Confidential Tender dated 24 January 2011 (Issue

00); Mabbett Confidential Tender Clarification Note dated 07 February 2011 (Issue 01); WRAP Instruction Letter (Ref:

FRA046-029v1-IL01v1) dated 14 February 2011; Mabbett Confidential Tender dated 09 August 2011 (Issue 00); and

WRAP Instruction Letter (Ref: FRA036-13-014v1-ILO2v1) dated 14 September 2011.

Mabbett would like to acknowledge and thank the following for their assistance and contribution during this programme of work:

The Strategic Forum for Construction Water Subgroup;

The construction companies who volunteered sites for audit;

Ms Carmen Snowdon (Senior Project Manager, Water Supply team) at WRc plc;

Mr Jim Wiltshire (Programme Area Manager – Design for Resource Efficiency) at WRAP;

Clugston Construction Ltd;

Lend Lease Corporation;

Sir Robert McAlpine Ltd;

Balfour Beatty Civil Engineering Ltd;

Clark Contracts Ltd;

Morgan Sindall plc;

Simons Group Ltd; and

Balfour Beatty Construction Ltd.

This report has been prepared by the following Mabbett personnel:

____________________________________ ____________________________________

Mr Michael Lynch, MEng, MIChemE Mr Paul Young, MEng, AMIChemE

Senior Environmental Engineer Environmental Engineer

Environmental Engineering Group Environmental Engineering Group

This report has been reviewed and approved by:

MABBETT & ASSOCIATES LTD

BY:

_____________________________________________

Mr Derek J. McNab, CEng, CSci, CEnv, FIChemE, MIEMA

Senior Environmental Engineer & Scientist

Environmental Engineering Group

6

1.0 Introduction

The following introduction is provided to set the scene for the project.

a. Within the construction sector the joint government and industry Strategy for Sustainable Construction, published

in 2008, highlighted the issue of water use by construction activities and included a number of targets pertaining to more efficient use of water. One such target identified water usage on construction sites as a priority area. The target, identified by the industry itself, is that:

“By 2012, water use in the manufacturing and construction phase to be reduced by 20% compared to 2008 usage”.

b. The body responsible for delivering the water target is the Strategic Forum for Construction (SFfC) and more

directly by SFfC’s Water Subgroup comprising representatives from industry including contractors, manufacturers, government departments and agencies. WRAP (Waste and Resources Action Programme) is a representative on the SFfC Water Subgroup.

c. The SFfC Water Subgroup developed an Action Plan to assist the construction industry in reducing the volume of

water used on construction sites. The Action Plan highlights two major themes. Firstly, the need to gather information on where water is used, and where water is wasted on construction sites, along with identification of suitable water conservation measures. Secondly, the Action Plan aims to improve site water use behaviour through embedding principles of water conservation throughout the construction process. A 2008 baseline figure of 148 m3 per £million contractors output at constant (2005) prices will be used to assess any improvement.

d. Mabbett & Associates Ltd (Mabbett) were commissioned by WRAP on behalf of the Subgroup to deliver a limited

programme of audit work before the end of March 2011 to support the Action Plan with the following objectives:

To develop robust primary data quantifying where water is wasted and the associated water using processes

on construction sites through a series of site audits across a range of sites.

To establish an evidence base of good practice for reduction of water use in the construction process.

This initial audit work is hereafter referred to as Phase I.

e. WRAP proposed a series of audits be carried out using a predefined methodology (and further refined by Mabbett to take account of the project time limitations) in delivering the required Phase I project outputs between 15 February 2011 and 31 March 2011; a total of 6 weeks.

f. It was envisaged that at least six (6) sites would be audited before the end of March 2011 across the following

project types:

civil engineering;

commercial offices;

commercial other;

commercial retail;

education;

healthcare;

industrial buildings;

leisure;

mixed use developments;

public buildings; and

residential.

In total, nine (9) sites were audited in this Phase I of work.

7

g. Mabbett were subsequently commissioned by WRAP to deliver a further programme of audit work over an extended period, hereafter referred to as Phase II. The objective of this work was to further develop the findings from Phase I, to include:

Longer term monitoring;

Capturing the outstanding high priority activities (e.g. hydro-demolition); and

Better quantifying the savings potential of conservation measures.

Three (3) sites were audited between November 2011 - April 2012. h. This summary report has been prepared by Mabbett - Environmental, Health and Safety Consultants and Engineers.

The findings, observations, and conclusions presented in this report, are limited by the scope of services outlined in the Mabbett Confidential Tender dated 24 January 2011 (Issue 00); Mabbett Confidential Tender Clarification Note dated 07 February 2011 (Issue 01); WRAP Instruction Letter (Ref: FRA046-029v1-IL01v1) dated 14 February 2011; Mabbett Confidential Tender dated 09 August 2011 (Issue 00); and WRAP Instruction Letter (Ref: FRA036-13-014v1-ILO2v1) dated 14 September 2011. The professional opinions and findings presented in this report are based on facts and information conveyed to, or observed by Mabbett during completion of the project. Furthermore, assessment and field operations have been performed in accordance with generally accepted engineering practices. No other warranty, expressed or implied, is made.

i. The first revision of this report was published in July 2011, and incorporated the findings from Phase I only. The

second revision of this report, published in August 2012, includes both the results of Phase I and Phase II.

8

2.0 Sites

The following sites were volunteered and received water audits. Site 1 - Site 9 relates to Phase I, and Site 10 - Site 12 relates to Phase II.

Table 2: Site Summary

Site Classification Project Use

Class Value

(£million) Project Type Audit Date

Constant Price Strategic Forum KPI (m3/£million

contractors output)

Potential Savings

Identified Processes Operational During Audit

1 Leisure Sports Hall/

Centre

7.2 Refurbishment 24 February 2011 170.6 13.0% Domestic and welfare facilities

2 Leisure Theatre 14.5 New Build 02 March 2011 77.2 19.8% Domestic and Welfare Facilities internal wet-trades Mortar Silos Dust Suppression - Block Cutting

3 Civil

Engineering Road 380.0 New Build 03 March 2011 92.5 24.3% Concrete Batching Plant

High Pressure Vehicle Washer Domestic & Welfare Facilities Hydraulically Bound Material (HBM)

Machine Caravan Park Laboratory Road Sweepers

4 Commercial Retail

Department Store

49.0 New Build 07 March 2011 11.5 18.5% Domestic and welfare facilities

5 Leisure Sports Hall/ Centre

93.0 New Build 11 March 2011 288.0 82.5% Domestic and Welfare Facilities Wheel Wash Mortar Silos High Pressure Washer

6 Civil Engineering

Road 445.0 New Build 14 March 2011 Unknown N/A Batching Plant Road Sweepers Domestic and welfare facilities

7 Education High School 23.0 Demolition and New Build

23 March 2011 182.0 15.3% Domestic and welfare facilities Agitator High Pressure Washer

8 Education University/ College

10.0 New Build and Refurbishment

23 March 2011 144.0 39.7% Domestic and Welfare Facilities Mortar Silos

9

Site Classification Project Use

Class Value

(£million) Project Type Audit Date

Constant Price Strategic Forum KPI (m3/£million

contractors output)

Potential Savings

Identified Processes Operational During Audit

9 Leisure Theatre Undisclosed New Build 29 March 2011 Unknown 22.2% Domestic and Welfare Facilities

10 Commercial & Residential

Call Centre, Department

Store, Apartments

150 New Build November 2011 – April 2012

57 21.3% Wet trades (e.g. block work, screeding, plastering, etc.)

Slip forming Welfare (toilets, food preparation

canteen and offices) Manual cleaning activities Drinking water

11 Civil Railway 50 New Build & Refurbishment

November 2011 – April 2012

Unknown N/A Drive-on wheel wash High pressure washing Vehicular dust suppression Welfare (toilets, food preparation

canteen and offices) Road sweeper Hydrodemolition Dust suppression (stockpile) Bentonite mixing Piling

12 Civil Airport 500 New Build November 2011 – April 2012

118 >15% Road sweepers Vehicular dust suppression Cleaning operations Dust suppression (stockpile) Welfare (toilets, food preparation

canteen and offices) Boot wash Bentonite mixing Mortar mixing Laboratory activities Crushing operations

Calculation of the KPI for each site is preliminary only, as the projects were on-going at the time of audit. Assumptions have been made in order to calculate each, using data which in some instances is limited.

10

3.0 Audit Methodology

3.1 Introduction The SFfC Water Subgroup has developed an Action Plan to assist the construction industry in reducing the volume of water used on construction sites. The collection of data on water using processes on sites and the identification of where water is wasted are the first steps of the Action Plan as there is currently very limited knowledge on this subject. A water audit methodology has been devised by the SFfC Water Subgroup as part of this Action Plan to assist the construction industry in reducing the volume of water used on construction sites. The priority for implementing water conservation measures on construction sites is on reducing water wastage with the following site processes identified by the SFfC Water Subgroup as likely to be the most water wasting activities:

dust Suppression, to include general, site road and wheel washing;

hydro-demolition with high pressure water;

cleaning, to include ready mixed concrete wagons and other applications; and

commissioning and testing of building plant/services.

Accordingly, the water audits were initially targeted on collecting information on these activities where available.

3.2 Validity & Limitations of the Collected Data This report presents the findings from nine (9) one day water audits, and a subsequent three (3) extended duration audits, across a wide spectrum of construction project types providing a start to understanding where water is used and where wastage occurs. While this is a start, the construction sector has a long way to go to develop a full understanding of water use on construction sites. The limited ~6 week duration of Phase I identified barriers including:

A lack of availability of suitable control sites, which reduces the options for estimating the savings associated with particular water using processes or behaviours.

Limited project duration which restricted the capture of the total volume of water used. As such, if the water consumed on the day of the audit was dissimilar to the average figure, the estimated water consumption of the site will be inaccurate.

Limited audit duration which restricted the identification of the proportion of total site use against each water using activity - an increase project duration will allow this information to be estimated with a greater degree of accuracy.

Weather related impacts (e.g. dust suppression and wheel wash activities not operating on a wet day in March), meaning some high priority activities could not be fully assessed.

The scheduling of audits to fit with the contacts from each of the companies volunteering the sites. While the data collected is robust relative to the sites’ water consumptions on the day of the audit, the implementation of a long-term monitoring plan on a sample of control sites is needed to begin to identify the following: ‘total volume used’ To understand the total volume used per activity it will be necessary to follow the

water using activity during the course of the construction process from groundwork through to project handover on a selection of control sites.

‘proportion of total site use’ Similarly, this parameter will only be understood when all the water using activities can

be captured on a control site during the full construction process. While it is envisaged the SFfC-devised water audit methodology will work well on a long-term monitoring opportunity, its use is restrictive to a ~6 week programme. To obtain the best value from the project, Mabbett worked in general accordance with the water audit methodology with our initial focus on identifying and quantifying water wastage of the high priority activities noted above (specific site processes where possible); identifying and quantifying water wastage of other activities; and identification of suitable control sites for further work. To ascertain the savings associated with potential water saving devices and practices (conservation measures), Mabbett used a combination of:

Actual monitored water use data gathered from the volunteered sites; and

Pre-existing knowledge of the water saving devices and practices and the typical reduction achieved from their use. It is key to note that the volume of water saved through a particular conservation measure will depend on the existing water using activity practice which may well be highly variable, especially where behavioural influences are a factor.

11

The extended ~6 month duration of Phase II allowed Mabbett to develop a more robust understanding of water consumption across the selected sites. It is noted, however, that no site has yet been audited from ground breaking through to project handover. Typically, sites which are of interest (i.e. those with large water consumption and which involve high priority water using activities) will run for a number of years, and so multi-year auditing would be required. Therefore, the project duration is still considered a barrier to following the SFfC Water Subgroup’s preferred audit methodology fully.

3.3 Overview of Mabbett Applied Methodology While Mabbett generally applied the water audit methodology noted in Appendix 10, our team made modifications to assist add value to the project, meet the limited project timelines and minimise the impact at the construction sites.

3.3.1 Phase I Rather than trying to put in place a long-term monitoring system which could potentially be a barrier to the project (i.e. another task for the staff at site), Mabbett utilised a combination of a non-intrusive ultrasonic flowmeter and manual meter reads to monitor water use generally over a one day period, where local circumstances allowed. This approach

had the benefits of overcoming the potential barriers of putting in place a long-term monitoring system e.g. the lead time and/or cost to install a meter, situations where no temporary power supply is available, etc. Where appropriate, Mabbett also used other direct measurement techniques to quantify water use such as a measuring cylinder and stopwatch, and indirect methods such as volume and time calculations, data taken from operating and maintenance manuals, calculations from basic principles (e.g. calculating flow from pressure), etc. In advance of an audit, our team requested the following data generally in line with the Form A - Preparation Checklist (see Appendix 10 for details): Table 3: Audit Data Request

Data Purpose

Personal Protective Equipment

Requirements

To ensure the Mabbett Team fully complied with the on site health and safety

rules during the auditing activities.

Copy of Water Supply Contract (or the terms of supply) and Wastewater Disposal Arrangements.

To understand the supply and charging arrangements which will assist us consider if there is a financial benefit to water efficiency or simply an environmental benefit. This data can assist prepare an economic argument for any water saving devices or practices.

Copies of Water and Effluent Bills

This tariff optimisation task will ensure the site is benefiting from the lowest fixed and variable costs.

Site Map To understand the site layout and water using areas.

Description of Construction Project

To provide an understanding of the project construction stages in relation to water efficiency and to assist compare against future construction projects.

Estimate of Construction Site Users and Associated Operating Plan

To understand the expected domestic use of water for assistance in constructing a water mass balance. This will be compared against actual 24 hour flow monitoring data to check for consistency and to identify any improvement opportunities.

Meter Inventory To build a picture of water use and on site flow monitoring strategy.

Water Using Equipment Inventory

To understand water using processes on site.

Domestic Arrangements To understand the water use for domestic arrangements on site (e.g. temporary toilet or fixed water supply).

Other Water Sources (borehole supply, river abstraction, tankered supply, etc.)

To provide data on all water sources supplying the construction site so an accurate and representative water mass balance is constructed and cost impact is understood.

Our approach while on site was to ‘follow the pipe’ starting from the site water supply through to point of use. This approach assisted us to minimise the risk of missing a water using activity which may have been overlooked by the site staff. We then recorded all important matters by compiling a photographic record on site and taking extensive notes. The Mabbett Team spoke with staff, both at managerial and operator level where possible, to gain their understanding

of water use, water efficiency and equipment use.

12

The Mabbett Team then completed: Form A - Preparation Checklist; Form B - Site Processes by Meter; and Form C - Data Collection (using Form D - Information for Form C) where appropriate - refer to Appendix 10 for further details. On return to our offices, the Mabbett Team interpreted the data collected and integrated the findings into this report.

3.3.2 Phase II

Due to the extended duration of Phase II, Mabbett were able to further improve upon the methodology utilised during

Phase I. These improvements included:

Multiple site visits and investigative work over a number of months; and

Installation of sub-meters and metered standpipes to improve robustness of quantitative information.

13

4.0 Water Saving Devices & Practices: General Activities

The following section is provided to set the scene for the water use on construction site generally.

4.1 Water Supply

The type of water used on site and the type of wastewater generated by site operations/activities will determine how

much a company pays for water supply and wastewater disposal. Generally the source of water for each of the sites is

either mains water or water abstracted from surface water.

There are a number of charging schemes for mains water and wastewater (sewerage, surface water and trade effluent

charges) in the U.K. with the amount paid depending on: the service provider, volume used, rateable value, and the size

of meter. Therefore, mains water is generally more expensive than direct abstraction. As a number of water using

activities on construction sites do not have to be of a potable standard, it is suggested construction sites consider the

use of Sustainable Urban Drainage Systems (SUDS) and/or settlement lagoons to collect surface water for at least part

of a sites water requirement.

As a result of the on site audit activities it is clear that that the type of water used plays a factor in water efficiency on

site with those sites that are charged for mains water supply on a volumetric basis generally having a better water

efficiency.

4.2 Housekeeping

Creating a culture within the construction sector that changes staff’s attitude and behaviour to accept ownership of

water efficiency is fundamental to improving the use of water in an efficient manner. Good housekeeping (e.g.

reporting/repairing leaks, turning off taps which are not in use, and generally using water in an efficient manner) can

assist a construction site reduce its overall water use. The range of attitudes identified across the sites that have been

audited is vast, from those that believe water should be minimised (almost regardless of cost impact) to those that view

water as a cheap commodity with a ‘don’t pay, don’t care’ attitude. None of the sites audited were able to provide

evidence of providing their site staff with regular awareness training on water efficiency, and this is an area which could

be improved. In this first instance, contractors should ensure that staff are aware of how much water is being

consumed, as well as any water efficiency targets which may apply at the site. Following this, general housekeeping

issues could be covered during a short workshop to help promote a water efficient culture over the duration of the

project. Lastly, if there are any water using applications which are particularly significant (e.g. concrete batching plant),

specific training could be provided to the relevant operators.

14

The following examples of poor housekeeping were identified during the site audits:

Image 1: Leaking Standpipe Image 2: Leaking Standpipe

Image 3: Leaking Mortar Silo

Leaks were notably the largest example of ‘poor housekeeping’ across the audited sites. As part of a site’s housekeeping programme, it is recommended that regular (e.g. monthly) walk-rounds are undertaken, for the purposes of leak

detection (and subsequent repair). Where walk-rounds are already undertaken for health and safety reasons, as was the

case at site 11, these could be combined to form a multi-purpose walk-round.

4.3 Monitoring and Targeting As has been evidenced by the SFfC Water Subgroup experience to date, there were few construction companies taking

regular meter readings. The amount of monitoring on site varied from no monitoring to regular weekly meter readings

being taken by on site staff.

There are 5 key areas which construction companies should consider. In typical order of priority, these are:

Ensure all areas of site water consumption are quantified.

Consider splitting welfare and “site-based” water consumption.

Record site water consumption on a regular basis.

Create Key Performance Indicators (KPIs) to assist tracking of water efficiency.

Utilise consumption or KPI data to set improvement targets.

4.3.1 Water Quantification

Construction companies should ensure all water sources are accurately quantified, though mains water is particularly important. This may include installing sub-meters at strategic locations around the distribution network, and/or utilising

metered standpipes. It is recommended that unmetered standpipes are gradually phased out of use at sites, regardless

of whether they are required by the utility provider.

Metered standpipes, which are not common throughout the UK construction sector, were purchased from the following

organisation for the Phase II work: www.aqua-check.co.uk/. A single 1” standpipe cost £242, and a 2.5” standpipe cost £618, excluding VAT. These are the most common standpipe sizes and should suit most applications. Some utility

providers may place restrictions on the type of standpipes which can be used. For example, Thames Water require

standpipes to be less than four years old, and fitted with a double-check valve – this should always be checked with the utility provider.

15

Quantifying consumption is the first step to improving water efficiency, and a number of sites did not currently undertake this practice.

Where water consumption is not recorded, implementing water efficiency improvements is made significantly more challenging.

4.3.2 Meter Readings

Regular meter readings should be taken from all meters, sub-meters and metered standpipes (weekly is recommended

in most instances) - this will allow the construction company to track how water consumption varies throughout a project, and may help identify (and eliminate) erroneous consumption. As part of this process, it may prove useful to

take regular out-of-hours meter readings - this helps confirm there are no leaks or other unwarranted consumptions.

4.3.3 KPIs

It is generally expected that water consumption throughout the different phases of a construction project will vary,

sometimes significantly so, as site operations will regularly change. As such, an increase in water consumption may not

necessarily mean water efficiency has reduced (or vice versa). By creating KPIs, which relate site water consumption to

some measure of site activity, it can help track water efficiency more accurately.

This will not always be a simple process for construction sites, due to the varying nature of site operations. Based on the

findings to date, it would appear ‘average staff numbers on site’ (or similar such as hours worked) over the monitoring

period may represent a suitable option in some instances. As such, the following could be tracked on a regular basis:

m3 of water consumed per average staff number on site

However, each site should be assessed on its own merit, and the most appropriate KPI selected.

Where sub-metering allows it, process-specific KPIs can be used. For example, where a concrete batching plant is sub-

metered, water consumption relative to raw material input or volume/mass of concrete produced could be used.

Note – the SFfC Water Subgroup’s 2008 baseline KPI of 148 m3 per £million contractors output at constant (2005) prices

is not intended to assess the performance of individual sites, as water consumption can be highly variable depending on

the construction activities taking place - it is solely for assessing the construction sector as a whole.

4.3.4 Targeting

Once the construction company is familiar with regular monitoring of water consumption and KPIs, this data can then be

used to set water efficiency targets for the site. For example, the site could target a 10% reduction in the average water

KPI over a period of 6 months. Such targets are a useful exercise to assist maintain an on-going focus on water

efficiency at the site.

4.4 Other Business Benefits As well as the direct financial benefit which normally applies to reducing water consumption (where water is charged for

on a volumetric basis), there are a number of other potential benefits which may apply, and which merit consideration. These include:

Reduced wastewater disposal costs (e.g. sewer discharge, tanker removal).

Reduced risk from potential water shortage, particularly in parts of England and Wales.

Improved Public Relations (PR) from highly visible water efficiency measures – atomising/misting dust suppression

equipment for sites in highly populated areas can be very effective.

Reduced need to tanker in water at relatively high unit cost.

Reduced energy consumption (where water is heated or cooled).

Reduced on-site treatment costs (where water or wastewater is treated before use/discharge).

Reduced environmental impact (e.g. in relation to environmental impact associated with water operators’ collecting, treating and distributing water in the mains network).

The direct cost of mains water is the most obvious expense when assessing water efficiency, but it can be seen that there are potentially a large number of additional business benefits which are relevant.

16

5.0 Water Saving Devices & Practices: High Priority Activities

The following section has been prepared based on information gathered/collected during the site audits which were

undertaken, and summarises good practice recommendations for the activities which have been identified as high

priority. Individual reports have been prepared for each site (see Appendices), and this section should be read in

conjunction with these reports.

The SFfC Water Subgroup has identified those activities expected to be ‘high priority’ i.e. the activities expected to

provide the greater opportunities for water efficiency savings. These are:

Table 4: High Priority Activities

Water Using Activity High Priority Activity

Dust Suppression General, site roads, wheel washes

Hydro-demolition with high pressure water

Cleaning

Ready mixed concrete wagons

Site/general cleaning

Specialist/high pressure cleaning

Commissioning & Test Building plant/services

As a general comment, contractors should firstly ensure that non-mains water sources are fully utilised (where it is

practical to do so) before considering how water efficiency on site can be improved. For example, abstracting water from

rivers, Sustainable Urban Drainage Systems (SUDS) or settlement lagoons on or near the site may provide water of

sufficient quantity/quality for a number of water-intensive actions, such as dust suppression or wheel washing. Where

using water in such a fashion, care must be taken to ensure that any legal requirements are met in the first instance

(e.g. suitable abstraction licence obtained from environmental regulator).

5.1 Dust Suppression (General)

The following table summarises where dust suppression (general) activities were noted/reported during the site audits:

Table 5: Dust Suppression (General) Summary

Site(s) Activity Comment

1 Manual spray units Small, manually operated spray units.

Area not deemed a high priority - current water consumption and potential for water savings deemed low. As such, this activity will not be discussed further here.

2 Block cutting Worker manually pours water from a bucket whilst block cutting is occurring.

Area not deemed a high priority - current water consumption and potential for water savings deemed low. As such, this activity will not be discussed further here.

6, 7 Rain guns High capacity rain guns are generally used to suppress dust from stockpiles, building demolition, etc.

Although this was not observed during any of the site audits, photograph evidence has been viewed for sites 6 and 7.

This is a high priority area with potential for significant water savings, and is discussed further below.

11,12 Open Hosing Open hosing can be used for general dust suppression where rain guns are considered excessive or are unavailable.

Although this was not witnessed at any site, it was reported as occurring prior to the commencement of the auditing.

This is a high priority area with potential for significant water savings, and is discussed further below.

17

5.1.1 Rain Guns & Manual Hosing

Rain guns are generally simple in operation - water is fired at a high velocity from the back of a water bowser over the

targeted area in order to suppress dust. The following photograph relates to operation of a rain gun at site 6:

Image 4: Rain Gun Operation

A similar system was used at site 7 during the demolition of a building.

Such systems can generally be considered water inefficient, due to the basic flow pattern (i.e. jet) which is apparent. No

manufacturer has been able to provide typical flow rates for an operational rain gun, but based on the apparent velocity

at which the water exits the bowser it is likely to be high. Assuming the flow rate is similar to that of a splash plate

system at full capacity (see Section 5.2.1 below for more details on splash plate systems), it may be in the region of

1,150 lpm (i.e. 69 m3/h). In reality, the flow rate may be higher. It is also likely to vary from system to system.

Manual hosing for general dust suppression is similar in practice to rain guns though operate on a smaller scale, and

may be used where rain guns are considered excessive or are unavailable. Similar to rain guns, the basic flow pattern is

inefficient and represents room for improvement.

A water efficient alternative to rain guns and open hosing for general dust suppression is fan misting systems.

5.1.2 Fan Misting Systems

By utilising fan misting systems, dust suppression efficiency can be maintained (or improved) relative to rain guns or

open hosing, whilst significantly reducing water consumption. Fan misting systems atomise the water prior to dispersion,

creating a more effective dust suppression pattern.

The following picture, taken from a manufacturer’s website, shows a fan misting system in operation – no such systems

were in use at any of the audited sites:

Image 5: Fan Misting System Operation

18

The water consumption of such a system will vary depending on the manufacturer/model. However, a typical

consumption may be in the region of 35 lpm (this is based on Ace Plant’s Dustfighter 7500MP). As such, it can be seen

that significant water savings are on offer relative to using rain guns.

The disadvantages of fan misting systems, relative to rain guns, may include:

More expensive to hire/purchase.

Power connection required, and so they are less mobile.

Mains quality water likely required (i.e. no river, SUDS or settlement lagoon water to be used).

General dust suppression activities will often by undertaken by sub-contractors, who may bring their own

plant/equipment to site, and water efficiency should be discussed with potential sub-contractors prior to site work

commencing - retrospectively considering water efficiency, after water inefficient plant/equipment is already being used

on site, adds complexity to the issue and reduces the chance of improvement. Where possible, sub-contractors who offer

water efficient alternatives to traditional plant/equipment should be preferred.

5.2 Dust Suppression (Site Roads)

The following table summarises where dust suppression (site roads) activities were noted/reported during the site

audits:

Table 6: Dust Suppression (Site Roads) Summary

Sites Activity Comment

3, 6, 11,

12

Dust Suppression

Vehicles

Dust suppression vehicles with splash plate operation were in use at sites 3, 6 and 11 (though not always on the day of the audit). Generally, splash plate systems are water inefficient, due to the rudimentary flow pattern of the water.

An operator from site 3 advised that SUDS water is used for their dust suppression vehicles, and that they vary the water output from their vehicle based on road conditions at the time. As such, although water inefficient splash plate systems are in use, there is no opportunity for mains water savings in this instance.

Site 6 either used river water or mains water for their dust suppression vehicles. No operator was available in order to discuss specific operating methodology.

Site 11 utilised abstracted groundwater within their dust suppression vehicle. As such, although water inefficient splash plate systems are in use, there is no opportunity for mains water savings in this instance.

Site 12 utilised a water efficient alternative to the traditional splash plate

method of operation (discussed further below), and did not represent an opportunity for improvement.

Where mains water is used, dust suppression vehicles with splash plate operation are a high priority area with potential for significant savings, and are discussed further below.

3, 4, 6,

11, 12

Road Sweepers Road sweepers were observed to be in use at sites 3, 6, 11 and 12, and were reported (but not observed) at site 4.

The operator at site 3 reported that he only uses water for dust suppression when road conditions require it, and that he also can control the water output (high and low pressure settings available).

The operator at site 6 reported that he also has high and low pressure settings, and will typically operate on the low pressure setting.

The operator at Site 11 utilised a single Johnston Sweeper 650 (containing a 1,300 litre water tank), which utilises a front-loaded spray bar and single spray nozzle adjacent to the side channel brush.

19

Sites Activity Comment

The operator has on/off control of each of these spray systems, and can also vary the flow rate from within the cab, and as such the road sweeper can be

considered relatively water efficient. The system also has a high pressure washer.

There are 2 contractors operating road sweepers on Site 12, hereafter referred to as Contractor A and Contractor B. Both contractors utilise Johnston Sweepers. Contractor A operates 2 VT650 road sweepers, which contain 1,300 litre water tanks. Contractor B operates 1 - 2 VT800 road sweepers, which contain 1,850 litre water tanks. The road sweepers utilise a front-loaded spray bar and single spray nozzle adjacent to the side channel brush. The operators have on/off control of each of these spray systems, and can also vary the flow rates from within the cab, and as such can be considered relatively water efficient. The systems also have a high pressure washer.

Some road sweepers have an optional water recirculation system, whereby a portion of the recovered wastewater is filtered and then transferred to the

clean water tank. This can provide water savings of up to 50%, though a figure of 30% may be more realistic. This is discussed further below.

5.2.1 Dust Suppression Vehicles (Splash Plate Operation)

Based on observations made during the site audits, as well as discussions with various contacts in the marketplace,

splash plate operation appears to be the most popular system-type for vehicular dust suppression. These rudimentary systems will typically direct high pressure (i.e. pumped) water against a flat metal plate at the rear of the vehicle to

create an outward spray pattern for dust suppression - see picture below:

Image 6: Splash Plate Operation

The basic spraying pattern which can be seen is water inefficient in terms of dust suppression. Typically, such a system

may consume around 1,150 lpm (this is based on ACE Plant’s Splash Plate system), and there is more advanced

technology on the marketplace which can achieve similar results with vastly reduced water consumption. One such system is the hydraulic spinning system, which is discussed further below.

5.2.2 Dust Suppression Vehicles (Hydraulic Spinning System)

As discussed above, the basic water pattern of splash plate operation is water inefficient for dust suppression systems.

By atomising the water to create a fine mist, similar (or better) results can be achieved using significantly less water - a picture of such a system in operation at Site 12 is shown below:

20

Image 7: Hydraulic Spinning System Operation

3 manufacturers were found who are able to provide such a system, and each used a hydraulic spinning disk to create

the necessary misting effect. Quantitative information was available from ACE Plant, who advise their gravity-fed hydraulic spinning system typically consumes around 100 lpm - this is around 9% of their equivalent splash plate

system. As such, as well as significant water savings, the time between re-fills is also lengthened - on larger sites, this

should prove an excellent additional benefit.

The disadvantages of hydraulic spinning systems, relative to splash plate systems, may include:

More expensive to hire/purchase.

Mains quality water likely required (i.e. no river, SUDS or settlement lagoon water to be used).

Vehicular dust suppression activities will often by undertaken by sub-contractors, who may bring their own

plant/equipment to site, and water efficiency should be discussed with potential sub-contractors prior to site work

commencing – retrospectively considering water efficiency, after water inefficient plant/equipment is already being used

on site, adds complexity to the issue and reduces the chance of improvement. Where possible, sub-contractors who offer

water efficient alternatives to traditional plant/equipment should be preferred.

5.2.3 Road Sweepers A typical industrial road sweeper will utilise water for dust suppression, as well as to agitate/loosen contaminants which are on the ground, when conditions require it. This is generally achieved by a front-loaded spray bar and single spray nozzle adjacent to the side channel brush. The vehicles may also have a stand-alone washer system for manual cleaning operations when the vehicle is stationary. Based on observations made during the site audits, most vehicles appear to be manufactured by Johnson Sweepers Limited (JSL), though the vehicle is typically “branded” with the operator’s company details. Additional information on the different JSL vehicles can be found at: www.johnstonsweepers.com/. There is generally a clean water storage tank, as well as a wastewater storage tank, located on-board. Water is sprayed from one or more outlets when the road sweeper is operational, and a portion of this water is collected from the ground via suction before passing to the wastewater storage tank for eventual disposal. A photograph of the side of Site 6’s road sweeper is shown below:

Image 8: Road Sweeper

A spray nozzle, sweeping brush and suction duct can be seen.

21

The normal capacity of a typical road sweeper may be around 35 lpm (based on JSL’s VT650 model). Based on the road sweepers which were analysed, the operators were generally able to reduce the water output (down to dry operation in some instances) based on the site conditions at the time. As such, the average water consumption of a typical road sweeper is likely to be significantly below capacity. Key water efficiency measures for road sweepers include:

Operators should have variable control of each spray bar/nozzle, to allow vehicle performance to be matched to actual requirements depending on site conditions.

Staff training (or discussion with sub-contractor) should be undertaken to ensure available controls are fully utilised to minimise water consumption (e.g. where possible, don’t just use water at full capacity).

Stand-alone washer system should be high pressure (low flow) type, with trigger-operated control (i.e. auto-isolation of flow).

Consider use of water recirculation system – this is discussed further below. In order to improve the water efficiency of road sweepers, it is possible to recycle a portion of collected wastewater. The following shows the system used by JSL, who are the only supplier to date who have been identified as a potential

provider of such a system:

Figure 1: Road Sweeper Water Recycling System (JSL)

Water saving data was requested, and JSL advised that typically savings of around 30% may be achieved, though up to 50% is possible. The 30% savings are based on reducing the operating flow rate from 7.2 lpm to 4.9 lpm. At this stage no recirculation systems have been assessed first-hand, and so these savings could not be confirmed. As well as providing water savings, a water recycling system will significantly lengthen the time between re-fills - on large sites, this is an excellent additional benefit. The biggest disadvantage to such a system may be the additional cost involved.

Road sweeping activities will often by undertaken by sub-contractors, who may bring their own plant/equipment to site,

and water efficiency should be discussed with potential sub-contractors prior to site work commencing – retrospectively

considering water efficiency, after water inefficient plant/equipment is already being used on site, adds complexity to the

issue and reduces the chance of improvement. Where possible, sub-contractors who offer water efficient alternatives to

traditional plant/equipment should be preferred.

5.2.4 Hard-standing Ground

Where feasible, the contractor should look to implement hard-standing roads, car parks, etc. across the site. In addition,

this should be done as early in the project as is practical. This should assist in reducing dust suppression requirements

(and thus water consumption) over the duration of the project.

5.3 Dust Suppression (Wheel Wash)

Note - the primary use of water in the following wheel wash systems is not for dust suppression, but is included in the

dust suppression section to remain consistent with WRAP’s previous publications.

22

The following table summarises where dust suppression (wheel wash) activities were noted/reported:

Table 7: Dust Suppression (Wheel Wash) Summary

Site Activity Comment

3 High Pressure Washer Site 3 was the only site where a manually operated wheel wash system was in operation. A high pressure washer was used to clean wheels, and also the general exterior of the vehicle. All water was collected in a sump, before passing to drain - no recycling of water took place.

This is a high priority area with potential for significant water savings, and is discussed further below.

4, 5, 6, 11

Drive-on Wheel Wash Drive-on wheel washing was observed in operation at site 5 and 11.

Although wheel washing systems were noted at sites 4 and 6, neither system was in use on the day of the audit.

The standard set-up of the drive-on wheel wash systems typically followed a standard format, which incorporated a settlement tank and a recycling system. However, both good practice (site 4) and poor practice (site 5) was noted.

This is a high priority area with potential for significant water savings, and is discussed further below.

5.3.1 High Pressure Washer (Wheel Wash)

The high pressure washer at site 3 is pictured below:

Image 9: High Pressure Washer

The ground around the washing area is hard-standing, and most of the wastewater will pass to a collection sump before

passing to drain. The system has a rated water consumption of 15 lpm. There are 2 main water inefficiencies associated

with a system such as this:

There is no attempt to recycle the wastewater for re-use.

Based on the picture above, it appears that operators may use the system to clean more than just the wheels of their vehicles. Potentially, this will lead to more water being used than is required to meet the minimum cleaning

standards required by the site.

As a general rule, manually operated wheel washing without water recycling should be avoided where it is practical to do

so. There are a number of suppliers across the UK market who can provide drive-on systems with built-in water

recycling, and who offer bespoke systems as well as their standard range to accommodate for most wheel washing

requirements. These systems are discussed further below.

5.3.2 Drive-on Wheel Wash

Site 4 typified good practice for wheel washing activities. A drive-on system with water recycling was located at the site

entrance - see pictures below:

23

Image 10: Drive-on Wheel Wash Settlement Tank Image 11: Drive-on Wheel Wash Wash Area

Wastewater from the wash area (picture right) is automatically recycled to the settlement tank (pictured left) for re-use.

In addition, when the settlement tank requires to be topped-up, water is pumped in from a nearby SUDS. As such, the

entire system has no mains water requirement.

Site 5 was an example of poor practice for drive-on wheel washing activities. The water top-up to the settlement tank

was uncontrolled - there is an open hose feeding mains water in, which runs constantly when the site is operational:

Image 12: Uncontrolled Top-up to Wheel Wash

Once this settlement tank is full, the water over-flows from a discharge pipe at the rear of the unit. Thus, the unit is

discharging suitable quality water to the ground for a significant portion of the time it is operational. In addition to the

uncontrolled top-up mechanism, the water pump remains on for a few seconds after a vehicle is finished washing. In

this short period an apparently large volume of water is sprayed outwards beyond the catchment system.

The mains water supply to the settlement tank was monitored for several hours and averaged at 37 lpm. As such, it can

be seen that a poorly controlled drive-on wheel wash may actually consume more than a manually operated high

pressure washer without recycling (~ 15 lpm - see Section 5.3.1 above for details). For this reason, it is key that drive-

on wheel washing systems are correctly installed, commissioned and maintained.

The following good practice is suggested for drive-on wheel washing systems:

Ensure water top-up to settlement tank is controlled. Typically, this can be achieved using a simple ball float-valve.

Ensure system is designed to switch off wash water pump as soon as is practical after vehicle has exited the wash area. If necessary, an optical sensor could be used to control this.

Ensure wash water supply pressure is set to correct level, through manual control of the isolation valve on the supply pipework (pictured below). The maximum (and normal) operating pressure will typically be in excess of what is required to achieve the required level of cleaning, particularly when site conditions are favourable. The operating pressure (and flow rate) should be adjusted on a regular basis to suit site conditions. This was trialled at Site 11 and the water consumption per wash was reduced from 94 litres to 40 litres (a 43% reduction) without any noticeable reduction in washing effectiveness.

Implement a regular cleaning schedule for the filter grille contained within the ultimate settlement tank (pictured below). If this grille becomes blocked, it can lead to an overflow from the settlement tank.

24

Image 13: Throttled Supply Valve Image 14: Filter Grille Cleaning

There are also waterless-type drive-on wheel wash systems available on the marketplace. These systems offer the maximum possible savings on water and energy, as they have no associated utility consumption. Instead, they rely on an angled grid system to flex the tyre treads open and closed repeatedly, which reportedly leads to contaminant

removal. These systems have not been witnessed at any of the audited sites and so no comments on their effectiveness can be made at this time.

5.4 Dust Suppression (Hydro-demolition with high pressure water)

Note - the primary use of water during hydro-demolition is not dust suppression, but is included in the dust suppression

section to remain consistent with WRAP’s previous publications. As part of Phase II, Mabbett undertook an assessment of two separate hydro-demolition projects. The first was associated with Site 11, and the second was not one of the twelve sites which received a full audit – it was visited solely to inspect the hydrodemolition activities. Both sites were utilising high pressure water to break-out concrete. Site 11 advised that hydro-demolition activities on site consume around 50 lpm of water when operational, but was unable to provide any additional information relating to system operation (e.g. pressure, level of breakout achieved, etc.). The second site reported they were using water at around 1,200 bar to break-out pre-cast concrete beams, which had been weakened due to fire. The flow rate of the water was around 50 – 55 lpm, and the site was able to break out around 1 m3 of concrete per day (over an 8 – 9 hour shift), which corresponds to around 25.5 m3 of water used per m3 of concrete broken out (25.5 m3 water/m3 concrete). It is suspected that the weakened nature of the concrete allowed an above-average rate of progress. The site operator reported this pressure and flow rate of water is typical for large volume concrete demolition. It was also noted by the site operator that in some instances (not at the site in question) they use ultra-high pressure hydro-demolition, which involves using water at a significantly reduced flow rate and around 2,750 – 3,450 bar. This is used where a more accurate level of hydro-demolition is required, and reduces the level of break possible markedly – perhaps by around 90%. Based on the two sites which were audited, it appears that around 50 lpm may be the typical water flow rate for large scale hydro-demolition of concrete. When operational, hydro-demolition is likely to be one of the largest water consuming activities at any construction site, and as such it is recommended that this water using activity is quantified (via sub-meter or metered standpipe) where possible. However, although these activities could not be inspected first-hand (due to the health and safety risk), it is suspected that the opportunity for water savings is relatively low. The reasons of this include:

25

Water flow rates are likely to be those required for efficient hydro-demolition, and as such may be unsuitable for reduction.

The primary concern during hydro-demolition activities is controlling health and safety, due to the relatively high risk of the activity. As such, staff training to improve break down levels (if it were deemed possible, which is currently unknown) is not considered a practical option for water savings.

Potentially, the hydro-demolition water could be re-used elsewhere on site, likely after some level of treatment. This would require assessment on a case-by-case basis, and would depend on a number of factors (e.g. the volume of water involved, water quality of re-use activity, etc.).

5.5 Chemical Additives There are a variety of chemical additives available on the UK market which may assist reduction in water consumption of dust suppression activities. For example, some additives act to reduce the surface tension of dust suppression water, which effectively increases the time taken for the water to dry out, and ultimately reduces the total volume of dust suppression water required.

One such additive, Calcium Magnesium Acetate (CMA), was trialled at Site 11 over a number of weeks during the Phase II work. CMA was added to the vehicular dust suppression bowser, which reportedly was able to reduce its water consumption by one-third without adversely affecting the level of dust suppression achieved. It should be noted that this particular additive can’t be used on site which are utilising bentonite, due to the risk of an adverse chemical reaction.

5.6 Control Systems Where possible, the contractor should ensure that dust suppression systems are specified (during the hiring/purchasing stage) with a sufficient degree of control over their operation to allow their operation to be altered (if required) for different applications, weather conditions, etc. Primarily, this will involve alteration of the water pressure and thus flow rate. For a nozzle-based distribution of water, the following graph shows how flow rate varies with distribution pressure:

Figure 2: Water Distribution Pressure Vs. Water Consumption (Jets, Nozzles and Orifices)

26

The following table provides some examples of situations where additional control of dust suppression systems may lead

to water savings:

Table 8: Dust Suppression System Additional Control Examples

System Comment

Rain Guns Consider that a rain gun is used for dust suppression during building demolition. The next time it is to be used, it is required to suppress dust from a stockpile, which may require a significantly different volume of dust suppression water.

If the pressure is variable, the rain gun will be suited to a greater number of applications, which should help minimise water waste.

Dust Suppression Vehicles (Splash Plate)

The flow rate of water required for dust suppression vehicles with splash plate operation will vary, depending on factors such as road width and weather. As such, if the water pressure can be varied, water wastage can be minimised.

Drive-on Wheel

Wash

The level of wheel washing required is likely to vary depending on the weather and site

conditions. A typical drive-on wheel wash systems may be designed on a ‘worst-case’ basis (i.e. it is capable of cleaning extremely dirty wheels). However, this level of cleaning may not be required in most instances. As such, by allowing variation in the wash water distribution pressure, water savings should be possible.

5.7 Cleaning (Ready Mixed Concrete Wagons)

The following table summarises where cleaning of ready mixed concrete wagons was noted/reported:

Table 9: Cleaning (Ready Mixed Concrete Wagons) Summary

Site Activity Comment

3 Cleaning concrete wagons Site 3 had a concrete batching plant on site. Concrete wagons were

washed internally at this area, prior to be being filled with concrete from the plant. Additionally, concrete wagons are washed externally after they have been filled. Wastewater is collected in a sump, and a portion of this wastewater is used as ingredient in the concrete batching process.

Cleaning of concrete wagons is a high priority area, and site 3 shows both good and poor practice in this respect - this is discussed further below.

7 Cleaning concrete wagons (externally only)

Site 7 has an on site agitator (i.e. stationary concrete wagon), which is regularly filled with concrete (via mobile concrete wagons) from a local concrete batching plant. Cleaning operations on site were limited to:

Third party mobile concrete wagons cleaning in and around their vehicle’s delivery chute, after delivering concrete into agitator. Each

wagon had its own water tank and hose in order to undertake these cleaning operations.

Cleaning concrete waste from around agitator area, using a hose or pressure washer associated with the system.

Cleaning operations at site 7 could be improved, though they are relatively small scale - most of the cleaning water in this instance will be associated with the mobile concrete wagons, once they get back to the batching plant (i.e. when cleaning wagon internally). As such, site 7 will not be discussed further below.

The concrete batching plant at site 3 consumes around 91.6 m3/week of water (average figure based on available meter

data), and this water is associated with the following applications:

Ingredient water used in concrete batching process.

Mains pressure hose for washing concrete wagons.

High pressure washer for cleaning batching plant ‘rotating heads’.

The current split of water consumption between each application is currently unknown.

27

Filling of a concrete wagon is shown below:

Image 15: Concrete Wagon Filling

In order to wash the wagons, a standard mains pressure hose (controlled by a quarter-turn isolation valve) is used:

Image 16: Mains Pressure Hose

Shown below is a picture of this system in use:

Image 17: Operational Mains Pressure Hose

28

Generally speaking, the wagons will be washed over hard-standing ground, and the wastewater will drain to a collection sump:

Image 18: Collection Sump

The water is then re-used as an ingredient in the concrete mixing process, although there is a maximum amount which can be used (reportedly around 50% by volume). However, once this sump is full, the wagons are washed adjacent to the hard-standing ground, and the wastewater passes to ground without recycling:

Image 19: Standby Wash Area

The concrete batching plant operator reported that they currently use as much recycled water as they can for concrete mixing, and as such, unless another use for the recycled water can be used, improved collection of wastewater (e.g. through increasing the sump volume) would not achieve any further mains water savings. The system at site 3 combines elements of both good and poor practice. The current method of recycling wastewater and using it as ingredient in the concrete batching process is good practice. However, utilising a mains pressure hose with a basic flow pattern (and which is controlled by a quarter-turn isolation valve) is water inefficient, and could be improved.

29

The following table summarises water conservation measures which could be considered good practice for washing concrete wagons: Table 10: Cleaning (Ready Mixed Concrete Wagons) Good Practice Measures

Water Conservation Measure Comment

Hard-standing ground of sufficient size and design around washing area.

This will ensure as much water as is practical is collected and passes to the wastewater sump for potential re-use.

Sufficiently designed wastewater sump. The sump should typically be sized to ensure that as much wastewater as can potentially be re-used (as ingredient or other re-use application) is stored. Where a degree of settlement is required prior to re-use, this should also be considered in the design.

Utilise high pressure washer Mains pressure hoses with basic flow patterns are generally water inefficient for cleaning operations. Use of a high pressure (low volume) washer, which has trigger-operated control, should act to minimise the volume of wash water which is required.

Operators should discuss their requirements with a number of potential vendors, to ensure that the correct system (e.g. most suitable nozzle technology, lowest volume flow which will still provide required level of cleaning, etc.) for the particular application is selected - see Section 5.8 below for more details.

Manage level of wastewater which is re-used

Where wastewater is to be re-used, the site should ensure that this is undertaken to the maximum, practical extent.

For example, where water is to be re-used as an ingredient in a concrete batching operation, the contractor should ensure plant operators are aware of exactly how much wastewater each concrete batch is allowed to use, before quality could potentially be compromised.

5.8 Cleaning (Site/General Cleaning/Specialist/High Pressure) Each manual cleaning application should be assessed on its own merit, and there are no absolute rules for water efficiency. However, by considering 3 key areas, water efficiency should generally be achieved - these are discussed further below. Typical cleaning activities, as observed during the site audits, include: Boot cleaning; Manual vehicle washing; and Rinsing soil/aggregate samples.

5.8.1 Auto-isolation of Flow The contractor should ensure flow from cleaning devices auto-isolates once it is no longer in use. In almost all instances, this will involve the use of trigger-control. This ensures there is no possibility of an unused cleaning device being left

operational (i.e. using water) when it is not in use. Both good and poor practice in this respect was observed at the audited sites. For standard hoses, trigger-operated spray guns should be used:

Image 20: Operational Trigger-operated Spray Gun

30

These devices are generally cheap, and can easily be retro-fitted if required. To reduce the risk of damage to the spray guns from being thrown onto the ground, a simple holding area could be installed near to the point of use, where the spray gun can be placed between uses. For high pressure washers, most will now normally come with trigger-operated lances:

Image 21: Operational Trigger-operated Lance

The contractor should ensure auto-isolation is included when purchasing/hiring high pressure systems, as it may prove difficult to retro-fit.

5.8.2 High Pressure (Low Flow) Washers Typically, using standard mains pressure hoses for cleaning applications will be water inefficient - the basic flow pattern and relatively low pressure are not conducive to efficient cleaning. As such, where the magnitude of cleaning activities merits it, high pressure (low flow) washers should be considered. These systems increase the water pressure, whilst reducing the flow, to provide efficient cleaning with less water. Some systems also utilise nozzle technology to create

more effective spray patterns - this allows a further reduction of water flow rate without adversely affecting cleaning performance. Three commonly used spray patterns are shown below:

Figure 3: Commonly Used Spray Patterns

Different applications are suited to different spray patterns, and there is no ‘good practice’ type. The contractor should look to identify the high pressure washer system which provides the required level of cleaning, with the lowest water pressure (and thus flow), to maximise the water savings on offer. Alternatively, a system with a variable flow rate can be specified, allowing a single system to be used for a number of different applications. This variable flow control is present on a number of the more common bowser-based systems, where a valve on the supply pipework can be manually throttled to reduce the flow rate to the required level.

31

In this instance, operators should ensure that the flow rate is reviewed for each application, and set to the desired level - simply using the system at its capacity flow rate each time should be avoided. Identifying the correct system can be achieved by consulting the marketplace, which is well developed for such systems.

5.8.3 Consult the Marketplace The marketplace for high pressure washers is well developed, and there are a high number of suppliers who look to cater for almost any foreseeable cleaning application. When looking to purchase/hire a new system, the contractor should consult multiple suppliers to discuss the specific requirements of their application, emphasising their preference for the most resource efficient system which will provide the necessary level of cleaning - in this way, a water efficient system is more likely to be obtained. Where is practical to do so, contractors should look to use systems which include recycling a portion of the wastewater. The contractor should try to avoid using a sole supplier for all site cleaning plant/equipment - they are unlikely to have the best option in every instance. Also, where possible, it may prove worthwhile to request a trial of any new system prior to agreeing the hire/purchase.

5.9 Commissioning & Testing Site 8 was audited with the intent of observing commissioning and testing operations. It was reported that water was being used for the flushing, pressure testing and filling of the following building services: heating and cooling (chilled water) systems; and hot and cold water supplies. Unfortunately, the site contact was unable to schedule this activity during the site visit due to changes to the work programme. As a result, time was spent with the commissioning engineer who advised that water is used during pre-commissioning (flushing and pressure testing) and commissioning (filling) activities. The flushing activities are intended to remove any foreign matter in the building services and simply consist of water being passed through the building services until the water runs clear. Pressure testing consists of filling the services, isolating the water within the services and raising the pressure to test for leaks. Finally, filling of the system for commissioning requires the system to be filled. It was advised that all commissioning and testing of building services would be undertaken using mains water (or water of a potable standard) to minimise the risk of system contamination. Furthermore, the commission and test of building services is covered under a number of guides published by BSRIA (owned by The Building Services Research and Information Association) e.g. Pre-commission cleaning of pipework systems 2nd Edition (AG 1/2001.1 (2004)), etc. By using building service rules of thumb, a boiler or chiller system volume will be equivalent to ten times the system power, therefore, a 100 kW boiler or chiller system will be approximately 1000 litres and a 200 kW boiler or chiller system will be approximately 2000 litres. Therefore, water use for the commission and test of building services is likely to be a relatively low and necessary water use. Mabbett suggest the following water conservation measures would be classified as good practice:

The construction sector should follow the advice in the relevant BSRIA guidance.

The water used for flushing building services should be isolated as soon as possible after the flush water turns clear.

It is recommended control sites are identified to quantify the water use during the commission and test of building services to obtain more robust data.

32

6.0 Water Saving Devices & Practices: Low Priority Activities As in Section 5 above, the following section has been prepared based on information gathered/collected during the site audits which were undertaken. Individual reports have been prepared for each site (see appendices), and this section should be read in conjunction with these reports. The SFfC Water Subgroup has identified those activities expected to be ‘lower priority’ i.e. the activities originally anticipated to provide less opportunity for water efficiency savings, than those high priority activities noted in Section 5. The activities considered of lower priority are: Table 11: Lower Priority Activities

Water Using Activity Lower Priority Activity

Site Cabins/Temporary Accommodation Toilets, catering, washing (personnel)

General Site Activities Tool washing

Rinsing

Wet Trades

Brick/blockwork

Screening

Concreting

Plastering

Core Boring

Lightweight Roofing

Ceramic Tile

Bentonite Mixing

Rendering

Groundworks Grouting

Drilling/Piling

Cleaning

Cleaning Tools and Small Equipment

Plant and Equipment

Paintbrush Washing

These activities are discussed further below.

6.1 Site Cabins/Temporary Accommodation This water using activity was identified during all of the site audits and comprises of various individual water using activities to include: toilets, wash hand basins, urinal flush, showers, catering and food preparation (i.e. welfare). It is important to note that Mabbett has identified that the water use associated with site cabins/temporary accommodation is likely to be a significant water using activity and should be considered by the SFfC Water Subgroup to be a high priority activity. While this area may generally be perceived as a low water use, it is the one constant during all phases of a construction project, and findings to date suggest it will account for a significant portion of a site’s total water consumption. During Phase II, the welfare water consumptions of site 10 and site 12 were estimated at 85% and 59% of total water

consumption respectively, during the monitoring period in question. Site 10, which had a full food preparation canteen and waterless urinals, consumed around 44 litres per person per day. Site 12, which had a full food preparation canteen, consumed around 34 litres per person per day. However, this did not account for the non-centralised toilet facilities (i.e. those located within the actual construction site), and as such the actual welfare consumption is higher than this. Each water using application is discussed further below. When installing domestic/welfare water savings devices, contractors should refer to the Water Technology List (WTL) in the first instance - more information can be found at: http://envirowise.wrap.org.uk/uk/Topics-and-Issues/Water/Key-Issues/Water-Technology-List.html The WTL not only ensures products are of a certain quality, but allows companies to reclaim 100% first year capital allowances through the Enhanced Capital Allowance (ECA) Scheme. Technologies currently on the WTL include:

efficient showers;

efficient taps;

efficient toilets;

flow controllers;

leakage detection equipment;

meters and monitoring equipment;

rainwater harvesting equipment;

vehicle wash water reclaim units;

water efficient industrial cleaning equipment; and

wastewater recovery and re-use systems.

33

6.1.1 Wash Hand Basins Each Wash Hand Basin (WHBs) seen on site had a cold tap which was directly fed from mains water. Generally, the tap was controlled by a turn mechanism, though some percussion (i.e. push) systems were noted. Shown below is the most common WHB-type (i.e. multiple WHBs, with individual turn-operated cold taps, and a common instant hot water heater):

Image 22: Wash Hand Basins

The most common water efficiency problems with this sort of systems are:

Flow from cold taps will vary directly with mains pressure, and will generally be too high (< 5 litres per minute is good practice).

Potential for taps to be left running for extended period (i.e. no auto-isolation of flow) for taps without percussion mechanism.

Due to basic flow pattern (i.e. no spraying) more water is required for effective cleaning.

The following is recommended as good practice for WHBs: Table 12: WHBs Good Practice Measures

Recommendation Comment

Pressure Reduction Valves (PRVs) Utilise variable Pressure Reduction Valves (PRVs) on feeds to WHB cold taps to set a maximum pressure (and thus flow rate). Ideally, a small number of PRVs would serve multiple applications (e.g. a single PRV to limit the pressure to an entire toilet cabin). If installing PRVs on lines of the distribution network that feed systems with a minimum operating pressure (e.g. instant hot water heater), care should be taken that minimum pressure requirements are maintained.

The average flow from all the WHB (cold taps) which were monitored was around 10.6 lpm. Good practice is represented by <5 lpm, and as such significant savings (>50%) may be available from pressure (i.e. flow) reduction alone.

Auto-isolation device Install devices to auto-isolate flow from cold taps after a set time period (e.g. ≤5 seconds). There are a number of potential options to achieve this (e.g. motion sensors) but a simple percussion mechanism (with variable operating time) should suffice, as long as it is maintained in good working order.

A typical cold tap may be left operational for 10 - 15 seconds. As such, limiting this to 5 seconds could achieve significant water savings (>50%).

Spray taps The basic flow pattern from a standard tap is water-inefficient for hand cleaning purposes. Spray taps work by forcing water through small holes in the tap outlet, thus producing a mist or spray, which is a more effective hand cleaning pattern.

Spray taps can reduce water use by up to 60% - 70% relative to conventional taps.

Note - the spray head needs to be checked regularly for fouling from soap, grease and limescale. Also, these devices are not recommended for areas of low use because the spray head can provide favourable conditions for legionella under such conditions.

As instant hot water heaters do not generally provide mains-pressure hot water, they represent less of an opportunity for water savings.

34

6.1.2 Sinks

Implementing water efficiency devices for sinks (which are typically located in canteen and office areas) is similar to that

of WHBs, though the potential savings may be less. This is because activities which require a set volume of water (e.g.

filling a kettle or a wash basin) will not benefit from their installation. Generally, percussion cold taps would still be

recommended. PRVs would only be recommended where a significant amount of sink activity is related to actions which

may potentially benefit from a reduced flow, such as:

Hand washing.

Dish/glass rinsing (not using a wash basin).

Where separate instant hot water heaters are available (which is normally the case), they can be used for the larger

volume activities (e.g. filling a wash basin).

Spray taps would not normally be recommended.

6.1.3 Toilet Cisterns Most toilet cisterns appeared standard size (i.e. ~ 6 – 8 litres), with a single lever flush mechanism, and did not appear to have any water efficiency devices incorporated. Where toilet cistern volumes of 7 litres or above are in use, the flush volume could be considered excessive and an opportunity for savings exists. Where looking to improve the water efficiency of toilet cisterns, the cistern volumes should be confirmed in the first instance. Where a cistern volume is 6 litres or less, retro-fitting of water efficiency devices is not recommended. However, where the cistern volume is 7 litres or more, consideration should be given to the installation of Cistern Volume Adjusters (CVAs). CVAs can sometimes be installed inside toilet cisterns to reduce effective flushing volumes (by displacing a portion of the water inside) without adversely affecting performance. Following discussions with the cistern manufacturer(s) to confirm suitability, CVAs should be installed in any cisterns with capacities equal to or above 7 litres.

Although larger (i.e. ~3 litres) CVAs are available, 1 litre ‘Save-A-Flush’ systems are recommended in this instance. More

information can be found at http://www.dry-planet.com/products.html.

CVAs may lead to savings of around 15%.

When purchasing new toilets, the contractor should look to ensure water efficiency has been incorporated from the

design phase, as this will typically provide greater water savings (and reduce the risk of operational difficulties) than

retro-fitting water saving devices. Although there are a number of options on today’s market, modern dual-flush systems

(i.e. 4 and 6 litre flush options) may be the most suitable. These systems may lead to savings of around 25% - 30%.

6.1.4 Urinal Cisterns Flushing of urinal cisterns was generally controlled well across most sites, though instances of poor practice were also noted. Poor practice is represented by timed flushing of urinals, where the cistern constantly fills with water and flush frequency does not vary with occupancy. Good practice involves installing a device to control the flushing based on how often the toilet is used. There are a number of options to achieve this, but good practice for the construction sector would normally involve the use of low maintenance hydraulic valves:

Image 23: Urinal Cistern Hydraulic Valve

35

A hydraulic valve can be fitted to the inlet pipework of the urinal system, and does not require power to operate. When

the inlet water pressure decreases temporarily through water being used elsewhere in the washroom (e.g. toilet flushing

or hand washing), the diaphragm-operated valve opens and allows a pre-set volume of water to pass into the urinal

cistern. When the cistern is full, the auto-siphon will discharge and flush the urinal. When the washroom is not being

used, the pressure remains unchanged and the valve remains closed. Thus, the cistern should not use water out with

working hours. It may also reduce water consumption throughout the day, depending on occupancy levels.

Controlling urinal flushing based on occupancy could lead to savings of >65% relative to timed flushing.

6.1.5 Showers

Most showers were standard electric showers, and retro-fitting some water saving devices (e.g. aerating shower-heads)

is generally not recommended with such systems. As such, where a shower flow rate is in excess of the flow required to

provide user satisfaction (typically 8 lpm - 10 lpm), simple flow regulation is recommended. Through installation of

variable PRVs, the flow rate from the showers should be set the minimum required flow to achieve user satisfaction.

Care should be taken to ensure any minimum operating pressures for electric showers are maintained.

Where new showers are being purchased, more advanced water saving devices should be considered from the outset.

6.1.6 Canteens

Self-catering canteens are the most common in the construction sector, and typically the only water efficiency concern in

these areas is sinks (see Section 6.1.2 above). With respect to food-preparation canteens, the only water efficiency

concern outwith WHBs and sinks that was noted was the washing area at site 3:

Image 24: Trigger-operated Washing Area

As can be seen, trigger-control to ensure auto-isolation of flow is fitted. Also, the sink is being filled with water (rather

than constantly running water). These 2 actions represent good practice for such areas.

6.2 General Site Activities

6.2.1 Tool Washing

No tool washing was observed during the site audits, and so there are no specific improvements actions suggested at

this time. However, good practice for tool washing would generally involve filling a container and using it to wash

multiple tools, rather than (for example) using on open hose.

36

6.2.2 Rinsing

Rinsing was observed at site 3 and site 12, in laboratories:

Image 25: Operational Rinsing

Trigger-operated control is the main concern with such systems, and it was installed in each instance. The contractor

should also ensure the flow rate is limited to the minimum required to achieve the required level of rinsing - this can be

achieved using a PRV or similar device.

6.3 Wet Trades

Water use for wet trades was observed to be generally efficient, and it is suggested this is not an area where significant

water savings are likely to be made (based on the observations made during the site visits - note that not all wet trades

were observed). As such, individual wet trades will generally not be discussed further in this report. However, due to the

potentially large volumes of water used for concreting and bentonite mixing, some brief comment is included on these

activities. This is followed by discussion of two of the more common water uses for wet trades.

6.3.1 Concreting & Bentonite Mixing

Where large volumes of concrete are used (e.g. site 10, where multiple concrete frame buildings are being erected), or

large volumes of bentonite are used (e.g. site 11, where a bentonite plant is installed), there is a corresponding large

volume of water being used (i.e. within the mix/as ingredient). Concrete can be brought to site ready-mixed in concrete

wagons, or mixed on site in a concrete batching plant. Based on observations made so far, bentonite is typically mixed

on site in a bentonite mixing plant. The water content of concrete and bentonite is strictly controlled for quality

purposes, and as such does not represent an opportunity for saving. However, where use of either product is expected

to be high (and the product is not brought to site ready-mixed), consideration should be given to quantifying the

associated water consumption using sub-meters or metered standpipes.

The chutes/pipework associated with concrete or bentonite delivery systems will be washed on a regular basis, typically

at the end of each working day, to prevent hardening within. Normally, this is undertaken by flushing the system with

water. In this instance, ensuring the water supply is isolated as soon as the water runs clear is the largest water

efficiency concern associated with the system. However, site 10 used a spherical projectile (i.e. a “pig”) to dry-clean the

pipework, as well as recovery valuable concrete product - this is best practice and should be considered where feasible.

37

6.3.2 Intermediate Vessels

Generally, intermediate vessels were filled for use throughout the day for wet trade operations:

Image 26: Wet Trade Intermediate Vessels

Water efficiency in this area may be helped by the logistics involved in filling these intermediate vessels. In this instance,

a water bowser was filled and crane-lifted to the top floor of the building (a multi-person task). This bowser was then

used to fill the intermediate vessels as and when required, for use throughout the day. The sooner the water bowser is

used, the sooner the operator was required to stop tiling and re-fill it with assistance from his colleagues.

Although this is an extreme example, the same principle in lesser forms generally applied at the sites audited (e.g.

operator has to leave working area and re-fill intermediate vessel at a stand-pipe on the other side of the site).

6.3.3 Mortar Mortar silos, which can generally be considered good practice, were observed at a number of sites:

Image 27: Mortar Silos

These silos contain dry, pre-blended mortar mix. When required this mortar mix is combined with water to produce mortar of the desired quality. The water in the mortar is strictly controlled for quality purposes, and as such there is unlikely to be any opportunity for efficiency improvements. The only other water requirement of these areas is generally following the preparation of a mortar batch - the delivery pipework is rinsed with water to flush out remaining mortar and prevent hardening inside.

The only likely opportunity for water wastage in this area is if an operator leaves the rinse water running and leaves the area following preparation of mortar batch - however, this was not observed at any of the audited sites, and as such is deemed unlikely. The chances of such an event occurring can be reduced by ensuring a culture of water efficiency is maintained.

38

Where mortar was used on site, but there were no silos in place, it was generally representative of small scale mortar use. This would involve bringing ready-mixed mortar to site in a vehicle, when required. No deliveries of this sort were observed, but are unlikely to account for any significant portion of a site’s water use.

6.4 Groundworks

6.4.1 Grouting No grouting was observed at any of the site visits, and so will not be discussed further here.

6.4.2 Drilling/Piling Site 7 was audited in order to assess the water use associated with drilling/piling operations. Most water use was associated with a hose and a high pressure washer using for cleaning the following areas:

Agitator.

Concrete delivery pump.

Concrete delivery lines.

Water efficiency for cleaning operations is discussed in Section 5.8 above, and as such will not be discussed further here. The only other water use associated with piling at site 7 was as an ingredient in the concrete - water content of concrete is strictly controlled for quality purposes and is unlikely to represent an opportunity for water efficiency savings.

6.5 Cleaning

Cleaning in this instance relates to the following activities:

Cleaning tools and small equipment.

Plant and equipment.

Paintbrush washing.

This was not observed to be a big water using area at any of the sites audited, and will not be discussed in detail here.

However, general good practice in these areas is represented by filling intermediate vessels (e.g. sinks, buckets, tanks,

etc) and re-using the water until its quality is sufficiently reduced that it requires replacing. A good example of this was

seen in the laboratory at site 3:

Image 28: Curing Tanks

These tanks were used for curing test tubes. The technician only changed the water once it became visibly fouled, which

was around once per month. A similar replacement system was in place at the laboratory at site 12.

39

7.0 Further Work Required

This section details additional work which is required in order to meet the objectives of the SFfC Water Subgroup.

7.1 High Priority Activity Auditing

It is the short term target of the SFfC Water Subgroup that a minimum of 5 sites are audited for each high priority activity. The following table summarises the work which has been undertaken to date:

Table 13: High Priority Auditing Summary

Water Using Activity Sites Audited Audits

Remaining

Dust Suppression (General) 4 (Sites 6, 7, 11 & 12) 1

Dust Suppression (Site Roads) 5 (Sites 3, 4, 6, 11 & 12) 0

Dust Suppression (Wheel Wash) 5 (Sites 3, 4, 5, 6 & 11) 0

Dust Suppression (Hydro-demolition with High Pressure Water) 2 (Site 11 & another) 3

Cleaning (Ready Mixed Concrete Wagons) 2 (Sites 3 & 7) 3

Cleaning (Site/General/Specialist/High Pressure) 7 (Sites 3, 5, 6 , 7, 10, 11 & 12) 0

Commissioning & Testing (Building plant/services) 1 (Site 8) 4

TOTAL AUDITS REMAINING 11

As such, it can be seen that in order to meet the short term requirements of the SFfC Water Subgroup, additional site

auditing is required. It is hoped that multiple high priority water using activities could be assessed at single sites, such that less than 11 individual site audits would be required.

It is recommended that the outstanding site audits are undertaken in a phased manner - for example, 5 more site visits could be scheduled, and following these 6 audits the need for further site audits re-assessed; it is possible that the

findings from the next phase of auditing may reduce the total requirement.

7.2 Auditing Methodology

The SFfC Water Subgroup initially proposed a more rigorous auditing methodology than was possible during Phase I, due to the short timescales (i.e. ~ 6 weeks from first audit until completion of this report). During Phase II Mabbett

attempted to follow the proposed methodology more closely, which allowed:

Installation of water sub-meters and metered standpipes in order to improve quantitative information.

Creation of a water mass balance for two of the selected sites.

Actual implementation of water savings devices/practices for certain activities.

For any subsequent auditing work, the following actions (in addition to those bulleted above) are recommended:

Following a construction project over its full duration - this has not yet been possible due to the restricted timescale

of each project phase, combined with the need to audit larger sites which run for multiple years.

Additional implementation of water savings devices/practices for certain activities, allowing accurate quantification of the savings which are achieved. This requires an increased level of assistance from the sites being audited, and

to date only a relatively minor level of implementation has been possible.

These actions will help develop further the current understanding from Phase I & Phase II.

7.3 Matrix of Sites for Water Audits

The SFfC Water Subgroup prepared a ‘Matrix of Sites for Water Audits’, which combined 11 different site types with 9 different construction phases. It was stated that the intention was to audit each combination of site type/construction

phase a minimum of 3 times, which corresponds to a minimum of 297 site audits. With 12 site audits undertaken to

date, the SFfC Water Subgroup is significantly below their intended target and more site visits should be scheduled.

40

Appendix 1

Site 1: Leisure (Sports Hall/Centre) Venue

Introduction Site 1, located in Scotland, was audited on Friday 25 February 2011. The following information applies to the project:

Value of Site (contractors output) £7,200,000

Footprint Area of Site (m2) 5,000

Typical Site Working Hours 48 working hours per week

Maximum Number of People on Site ~ 70

Phase of Construction Final phase (fit-out, test and commission)

Classification Leisure

Project Use Class Sports Hall/Centre

Project Type Refurbishment

Construction Type Concrete Frame and Steel Frame

Client Type Local Government

Contractual Agreement Individual Company

The site was first closed for refurbishment in October 2008, and was initially scheduled to be re-opened around 14 months later. However, significant delays followed, and the site is now scheduled to be re-opened on 28 May 2011. There are typically around 45 people working on the site at any one time.

Water Supply There is one Scottish Water/Business Stream meter which serves the site (presumably this meter served the facility prior

to commencement of the development). The Project Manager was unable to advise what charging scheme, if any, is in place for their water consumption. With little apparent benefit from water efficiency activities on site, this may act as a barrier to improvement. A detailed water schematic for the site does not currently exist.

Site Water Consumption The water supply to the site was monitored using a clamp-on ultrasonic flow-meter as the stand-pipe exited the ground:

41

The following chart shows the results of the profiling exercise, which took place between 09:39 - 16:52:

The negative readings are likely to be caused by water flowing down the vertical stand-pipe when there is no site water demand. The average consumption over the monitoring period was 0.19 m3/h. Based on a 48-hour working week, the weekly consumption may be around 9.12 m3/week. Assuming the project runs from mid-October 2008 until mid-May 2011, and this average water consumption applies throughout, the total water consumption over the duration of the project may be around 1,228.6 m3. Based on the value of the site as noted above, the Current Price Strategic Forum Key Performance Indicator (KPI) for the project would be around:

170.6 m3/£million contractors output

A meter reading was taken from the main Scottish Water/Business Stream at 09:40 on the day of the audit: 20,488.8 m3. No subsequent meter readings have been taken.

Water Consuming Areas/Applications

The following table summarises the main water using areas/applications on site:

Area/Application Comment

Scottish Water/Business Stream Meter & Stand-pipe The red circle in the picture below highlights where this meter is located:

The blue circle highlights where the stand-pipe, which provides all water used for construction purposes, rises from the ground.

The Scottish Water/Business Stream meter is located near to the South-Western corner of the site. After rising from the ground, the pipework splits into three main distribution networks - these supply:

Domestic/welfare facilities

Water draw-off point for side of site closest to stand-

pipe

Water draw-off point for side of site furthest from stand-pipe

42

Area/Application Comment

Domestic and welfare facilities

The domestic and welfare facilities are located to the East of the site, and incorporate:

Toilets

2 x canteens (self-preparation)

Sink (located in main office) The individual areas are fed by flexible plastic (MDPE) pipework.

Water Draw-off Point for side of site closest to stand-pipe After branching off from the stand-pipe, a flexible plastic hose entered the building:

This water draw-off point was unused at the time of the audit.

Water draw-off point for side of site furthest from stand-pipe After branching off from the stand-pipe, flexible plastic pipework ran around the perimeter of the building (externally) until it terminated at a draw-off point:

A flexible plastic hose was connected to the draw-off

point, which entered the building nearby.

This water draw-off point was unused at the time of the audit.

43

No other current water consuming areas/activities were reported by the contractor, or noted during the site audit. The following activities were reportedly undertaken previously, or will be undertaken at a future stage of the project:

Dust suppression (small, manually operated spray units)

Filling of the swimming pool

High pressure washer (being used in this phase of the project, but not on site on day of audit)

Water Mass Balance Based on the information available at present, the following provisional water mass balance for the site has been prepared:

Activity Water Use (m3/week)

Domestic and Welfare Facilities 6.19

Draw-off Points 2.93

Total 9.12

This is based on the water consumption of the site on the day of the audit. The domestic and welfare water consumption has been estimated based on 45 people consuming 25 litres per day (for facilities without a food-preparation canteen), over a 5.5-day working week. The draw-off points consumption is simply the total consumption minus the domestic and welfare facilities consumption. To improve the accuracy of the water mass balance for the site, sub-metering of each draw-off point, as well as the domestic and welfare facilities feed, is recommended.

Areas of Opportunity The following table summarises the areas of opportunity for water efficiency improvement actions on site:

Action Water Savings

(m3/week)

Domestic & Welfare Facilities - Efficiency Improvements 1.1

Monitoring and Targeting 0.09

Total 1.19

As such, it is estimated that the contractor could reduce site water consumption by around 13%. Further details on

these actions are outlined below,

Domestic & Welfare Facilities - Efficiency Improvements Wash Hand Basins/Sinks

All the Wash Hand Basins (WHBs) and sinks on site are directly fed from mains, and generally have turn-mechanisms or percussion (i.e. push) buttons to control the cold outlets:

44

A selection of (cold tap) volume flows were monitored, and the followings results obtained:

Area Application Measured

Volume Flow

(lpm)

Good Flow

(lpm)

Fair Flow

(lpm)

Poor

Flow

(lpm)

Comment

Male Toilet WHB 4.8

<5 5 - 10 >10

Good performance achieved

Canteen (Ground Level)

Sink 15 Poor performance achieved

Canteen (Upper Level)

Sink 10.3 Poor performance achieved

Site Office Sink 12.6 Poor performance achieved

As such, 3 of the 4 areas monitored performed poorly - this is common where the feed is mains pressure. Note also that

the flows will vary directly with mains pressure, which is likely to vary throughout the day.

In addition, the control mechanisms in some areas could be improved. The toilet WHBs (pictured above) and the site

office sink have turn mechanisms, and this introduces the possibility of leaving the taps running for longer than is

actually required. Also, the percussion mechanism which controls the Canteen (Ground Level) sink operates for around 1

minute 10 seconds when activated - this is far in excess of actual requirements.

The following improvements are recommended:

Percussion mechanisms fitted to toilet WHBs (cold tap only)

Adjust (or replace) site office sink percussion mechanism

Install Pressure Reduction Valve (PRV) to reduce operating pressure (and thus flow) to the following areas:

- Canteen (Ground Level)

- Canteen (Upper Level)

- Site Office

This will ensure a maximum distribution pressure and/or operating time, thus minimising wastage.

Note - if the contractor is convinced that most activities at the sinks will use the same volume of water independent of

flow (e.g. filling a kettle), then installation of PRVs is not recommended - this is only recommended where volume is not

independent of flow (e.g. hand washing, glass rinsing, etc.).

Toilet Cisterns

The toilet cisterns appeared standard size (i.e. ~ 6 - 8 litres), with a single lever flush mechanism, and did not appear to

have any water efficiency devices incorporated.

45

In the first instance, the cistern volumes should be confirmed. Where a cistern volume is 6 litres or less, retro-fitting of

water efficiency devices is not recommended. However, where the cistern volume is 7 litres or more, consideration

should be given to the installation of Cistern Volume Adjusters (CVAs). CVAs can sometimes be installed inside toilet

cisterns to reduce effective flushing volumes (by displacing a portion of the water inside) without adversely affecting

performance. Following discussions with the cistern manufacturer(s) to confirm suitability, CVAs should be installed in

any cisterns with capacities equal to or above 7 litres.

Although larger (i.e. ~3 litres) CVAs are available, 1 litre ‘Save-A-Flush’ systems are recommended in this instance. More

information can be found at http://www.dry-planet.com/products.html.

Estimated Savings

Assuming 70% of the water consumption of the domestic and welfare facilities is associated with WHBs/sinks and toilet

flushing, and that 25% savings can be achieved, weekly savings of around 1.1 m3/week could be achieved.

Monitoring & Targeting

It is recommended that the contractor implement a simple Monitoring and Targeting (M&T) system for the site’s water

consumption - initially requiring the installation of a sub-meter, this will then involve undertaking two main actions on a

regular basis (at a minimum):

Track water consumed (m3) per week, and assess for erroneous consumption.

Once per month, conduct brief out-of-hours assessment of baseload water consumption.

These actions should help identify (and eliminate) unnecessary water consumption on site.

The contractor can also consider utilising KPIs, which relate water consumption to some measure of site activity (e.g.

average staff numbers on site over the monitoring period).

Estimating the savings associated with such an action is difficult, and an arbitrary figure of 1% of the current site water

consumption will be used - this accounts to 0.09 m3/week.

46

Appendix 2 Site 2: Leisure (Theatre) Venue

Introduction

Site 2, located in England, was audited on Wednesday 02 March 2011. The following information applies to the project:

Value of Site (contractors output) £14,500,000

Footprint Area of Site (m2)

Total area of site unknown. Individual floor areas of completed development as follows:

Ground Floor: 3,000 m²; First Floor: 950 m²; Second Floor: 320 m²; Third Floor: 250 m2

Typical Site Working Hours

Monday - Friday: 07:30 - 17:30 (generally, most people left by 17:00)

Saturday: 08:00 14:00 (only sometimes)

Sunday: N/A

Maximum Number of People on Site ~ 120 (only for previous stages of the project)

Phase of Construction Main external envelope nearing completion. Finishing trades internally on-going.

Classification Leisure

Project Use Class Theatre

Project Type New Build

Construction Type Steel Frame

Client Type Local Government

Contractual Agreement Other (One-off Contract)

There are currently around 70 persons undertaking work at the site - the maximum figure of 120 persons is more applicable to the initial phases of the project.

Although the Project Type is listed as New Build above, demolition work was undertaken by the council in 2008 prior to the contractor’s involvement. Also, some minor refurbishment work (of the original entrance) is taking place - this area was not demolished.

The project started at the end of April 2010, and the contractor predicts it is around 50% complete.

Water Supply

There is one water meter which serves the site. A detailed water schematic for the site does not currently exist. As well as the water supply to the site Cabin Compound (which contains the domestic and welfare facilities), a branch feeds off to the South-side of the site along the boundary fence. There is one take-off which heads into the main building (and feeds an open hose, which is used to fill an Intermediate Bulk Container (IBC)), and the main pipework continues along the boundary fence till it feeds the mortar silos at the west-side of the site.

Site Water Consumption

The water supply to the site was monitored using a clamp-on ultrasonic flow-meter:

There were 2 sinks in the office area which are not accounted for under this monitoring exercise, though it is likely they are relatively insignificant in terms of the overall site water consumption.

47

The following chart shows the results of the profiling exercise, which took place between 10:33 - 16:03:

The average consumption during this time was 0.255 m3/h. Based on a 50-hour working week, the weekly consumption may be around 12.8 m3/week. Assuming the project commenced on 30 April 2010, that it was 50% complete on the day of the site audit, and that the weekly water consumption noted above is the average water consumption at the end of the project, the total water consumption of the project may be around 1,119 m3. Based on the value of the site as noted

above, the Current Price Strategic Forum Key Performance Indicator (KPI) for the project would be around:

77.2 m3/£million contractors output In order to calculate the site water consumption and KPI figures with a greater degree of accuracy, the contractor could refer to their water bills. However, the water bill provided to the audit team (for the period 17 September 2010 - 27 January 2011) contained only the front cover - this had only financial information noted.

Water Consuming Areas/Applications The following table summarises the main water using areas/applications on site:

Area/Application Comment

Water Meter

Water meter located adjacent (externally) to the North-East

corner of the site.

48

Area/Application Comment

Domestic and Welfare Facilities

The domestic and welfare facilities are located to the East of the site, and incorporate: Toilets 3 x canteens (self-preparation) 2 x sinks (located in main office) The individual areas are fed by flexible plastic pipework.

Water Supply (Lower Levels)

There is a water drum located inside the ground floor of the building, which is topped-up as and when required. It is currently used for internal wet-trades (e.g. tiling) on the lower levels, and the contractor estimates it is topped up every 2 - 4 days. Assuming a drum volume of 250 litres (i.e. 55 gallons), and that the container is filled twice per week, this may account for around 0.5 m3/week of water.

Mortar Silos

There are 2 Tarmac Dry Silo Mortar Silos on site, which contain dry, pre-blended mortar mix. When required this mortar mix is combined with water to produce mortar of the desired quality. The water in the mortar is strictly controlled for quality purposes, and as such there is unlikely to be any opportunity for efficiency improvements. The only other water requirement of this area is following the preparation of a mortar batch - the delivery pipework is rinsed with water to flush out remaining mortar and prevent hardening inside. More information can be found at: http://www.tarmacbuildingproducts.co.uk/

Dust Suppression - Block Cutting

When cutting blocks, water is manually poured over the cutting area to act as a dust suppressant. Based on the observations made whilst on site, this is unlikely to be a large water consumption.

49

Area/Application Comment

Water Supply (Upper Levels) The water bowser pictured below is used to provide water to the upper levels of the building:

When working on upper floors of the building, the mains water pressure is insufficient and as such a water bowser is filled and acts as the water supply. This requires lifting using a crane. This was providing water for internal wet-trades on the day of the audit. Due to logistics involved in filling and lifting this water bowser to the upper floors (i.e. time consuming and requires multiple persons to undertake), there is unlikely to be much water waste.

Wet-trades (Upper Levels)

The containers pictured are filled using the water bowser, and are used for internal wet-trades (e.g. tiling) on the upper levels of the building.

Spray Plaster Machine

The spray plaster machine was not operational during the audit, and could not be accessed fully to obtain further details.

No other current water consuming areas/activities were reported by the contractor, or noted during the site audit.

50

Water Mass Balance Based on the information available at present, the following provisional water mass balance for the site has been prepared:

Activity Water Use (m3/week)

Domestic and Welfare Facilities 9.6

Water Supply (Lower Levels) 0.5

Mortar Silos

2.7 Dust Suppression - Block Cutting

Water Supply (Upper Levels)

Total 12.8

This is based on the water consumption of the site on the day of the audit.

The domestic and welfare water consumption has been estimated based on 70 people consuming 25 litres per day (for facilities without a food-preparation canteen), over a 5.5-day working week. The water use of mortar silos, dust suppression - block cutting and water supply (upper levels) combined (i.e. 2.7 m3/week) has been estimated based on the total consumption (12.8 m3/week) minus the know consumptions (i.e. 9.6 + 0.5 m3/week). To improve the accuracy of the water mass balance for the site, sub-metering of each area is recommended.

Areas of Opportunity The following table summarises the areas of opportunity for implementing water efficiency actions on site:

Action Water Savings (m3/week)

Domestic & Welfare Facilities - Efficiency Improvements 2.4

Additional Considerations 0.13

Total 2.53

As such, it is estimated that the contractor could reduce site water consumption by around 19.8%.

Further details on these actions is outlined below,

Domestic & Welfare Facilities - Efficiency Improvements

Wash Hand Basins/Sinks

Most of the Wash Hand Basins (WHBs) and sinks on site are directly fed from mains, and generally have turn-

mechanisms to control the cold outlets (except the 2 site office sinks, which have percussion mechanisms). There are a

number of efficiency problems with this sort of system, including:

Flow from taps will vary directly with mains pressure, and will generally be too high (< 5 litres per minute is good practice).

Potential for taps to be left running for extended period (i.e. no auto-isolation of flow).

Due to basic flow pattern (i.e. no spraying) more water is required for effective cleaning.

There are a number of options open to the contractor to resolve this situation. In this instance, the following is

recommended:

Installation of PRVs on the water supply to each WHB and sink with a flow in excess of 5 lpm (consider whether

one PRV could be installed to control all 3 of the canteen sinks).

Replace existing taps with percussion-controlled equivalent (except those which already have such a system installed).

This will ensure a maximum distribution pressure and/or operating time, thus minimising wastage.

51

Note - if the contractor is convinced that most activities in the canteens and site offices’ sinks will use the same volume

of water independent of flow (e.g. filling a kettle), then installation of PRVs is not recommended - this action is only

recommended if the volume is not independent of flow (e.g. hand washing, glass rinsing, etc.).

Toilet Cisterns The toilet cisterns appeared standard size (i.e. ~ 6 - 8 litres), with a single lever flush mechanism, and did not appear to have any water efficiency devices incorporated.

In the first instance, the cistern volumes should be confirmed. Where a cistern volume is 6 litres or less, retro-fitting of water efficiency devices is not recommended. However, where the cistern volume is 7 litres or more, consideration should be given to the installation of Cistern Volume Adjusters (CVAs). CVAs can sometimes be installed inside toilet cisterns to reduce effective flushing volumes (by displacing a portion of the water inside) without adversely affecting performance. Following discussions with the cistern manufacturer(s) to confirm suitability, CVAs should be installed in any cisterns with capacities equal to or above 7 litres.

Although larger (i.e. ~3 litres) CVAs are available, 1 litre ‘Save-A-Flush’ systems are recommended in this instance. More

information can be found at http://www.dry-planet.com/products.html. Urinal Cisterns At present, it appears that the 2 urinal cisterns in the toilet flush on a timed basis, regardless of occupancy. As such, they will sometimes use more water than is required during normal working hours, and will always consume more water than required out with normal working hours. It is recommended that a hydraulic valve is fitted to each to manage their water consumption based on occupancy. A hydraulic valve can be fitted to the inlet pipework of the urinal system. When the inlet water pressure decreases temporarily through water being used elsewhere in the washroom (e.g. toilet flushing or hand washing), the diaphragm-operated valve opens, allowing a pre-set amount of water to pass to the urinal cistern. When the cistern is full, the auto-siphon will discharge and flush the urinal. When the washroom is not being used, the pressure remains unchanged and the valve remains closed. Thus, the cisterns should not use water out with working hours.

Estimated Savings Based on a 25% reduction in the water consumption of the domestic and welfare facilities, weekly savings of around 2.4 m3/week could be achieved.

Additional Considerations Monitoring & Targeting It is recommended that the contractor implements a simple Monitoring & Targeting (M&T) system for the site’s water consumption - this will involve undertaking two main actions on a regular basis:

Track water consumed (m3) per week, and assess for erroneous consumption.

Once per month, conduct brief out-of-hours assessment of baseload water consumption.

These actions should help identify (and eliminate) unnecessary water consumption on site. The contractor can also consider utilising KPIs, which relate water consumption to some measure of site activity (e.g. average staff numbers on site over the monitoring period). Trigger-operated Control The draw-off point on the lower levels was controlled by a quarter-turn isolation valve. Although this was not observed to be leading to any inefficiencies, general good practice suggests trigger-operated spray-gun control should be installed.

52

Maintenance As a consequence of regularly moving location, flexible water pipework on construction sites can be prone to minor damage resulting in leaks (as per the following pipe associated with the mortar silos):

The contractor should ensure all water pipework is maintained regularly, and any leaks (such as that pictured above) are repaired once observed. Estimated Savings There is not currently enough information to estimate the savings associated with these actions, and as such an arbitrary figure of 1% of the current site water consumption will be used - this accounts to 0.13 m3/week.

53

Appendix 3 Site 3: Civil Engineering (Road) Site

Introduction Site 3, located in England, was audited on Thursday 03 March 2011. The following information applies to the project:

Value of Site (contractors output) £380,000,000

Length of Scheme (km) 28

Typical Site Working Hours

Monday - Friday: 07:00 - 19:00 (summer) 08:00 - 17:30 (winter)

Saturday: N/A

Sunday: N/A

Maximum Number of People on Site 750

Phase of Construction Around 50% of the road has been completed.

Classification Civil Engineering

Project Use Class Road

Project Type New Build

Construction Type Civil Engineering

Client Type Government Agency

Contractual Agreement Individual Company

It is estimated that it will be around 14 months (from the audit date) until completion. Some sections of the existing road will be retained for use by local traffic and some sections will be downgraded for use by cyclists, walkers and horse riders and for private means of access. The average number of staff on site is around 650.

Water Supply The main site compound appears to get its mains water from an adjacent armed forces base. Current charges are 1.3835 £/m3 for water purchase, and 0.8439 £/m3 for wastewater disposal, totalling 2.2274 £/m3. Within the main site compound, the three main areas are sub-metered:

Concrete Batching Plant

Caravan Park

Site Compound - Remainder

There are also a high number (around 14) of individual stand-pipes which provide mains water at various points across the site - each stand-pipe is monitored, though the current charging scheme for each is unknown.

Site Water Consumption The following table summarises the consumption of the 3 main distribution networks on the main site Compound since March 2010:

Distribution Network Weekly Consumption (m3)

Concrete Batching Plant 91.6

Caravan Park 95.7

Site Compound - Remainder 61.5

TOTAL 248.8

The following charts summarise the variation in the Specific Water Consumption (SWC) of the Concrete Batching Plant, Caravan Park and the Site Compound - Remainder:

54

55

Each stand-pipe used on site is also monitored, and the following table summarises the total water which has been consumed through each:

Meter Reference Reading (m3) Latest Meter Read Date

09A003424 22 November 2010

09A003446 87 January 2010

09A003440 24 January 2010

09A064203 110 November 2010

09A064227 546 November 2010

08A152202 15 November 2010

08A152203 17 November 2010

08A152205 81 November 2010

08A170904 268 June 2010

08A170905 255 June 2010

09A037803 17 November 2010

09A037804 131 November 2010

09A037805 126 November 2010

09LU0022871 391 November 2010

TOTAL 2,090 N/A

This is based on meter readings taken between November 2009 and November 2010 (i.e. 12 months). Assuming the total project duration is 28 months, the total volume consumed via the standpipes may be around 4,877 m3 if the average consumption remains the same. This corresponds to around 40.1 m3/week. Based on a 28 month (i.e. ~121.6 weeks) project duration, and assuming the weekly consumption averages remains the same as noted above, the total mains water consumed over the duration of the project may be around 35,131 m3. Based on the value of the site as noted above, the Current Price Strategic Forum Key Performance Indicator (KPI) for the project would be around:

92.5 m3/£million contractors output

Water Consuming Areas/Applications The following table summarises the main water using areas/applications on site:

Area/Application Comment

Concrete Batching Plant

There is a 63 mm (diameter) water pipe providing water to the Concrete Batching Plant. Since meter readings commenced on 05 March 2010, the plant has consumed 4,748 m3 of water (which corresponds to around 91.6 m3/week). As well as water used as an ingredient in the concrete batching process, there is a hose and a high pressure washer used for cleaning purposes. There is a sump which collects a portion of this wash water, and this recycled water can be used as ingredient in subsequent batch mixing.

Concrete Batching Plant - Hose

There is a mains pressure hose, controlled by a quarter-turn isolation valve, used for cleaning purposes (including cleaning the concrete wagons).

56

Area/Application Comment

Concrete Batching Plant - High Pressure Washer

There is a Fillsafe Systems Limited (http://www.fillsafe.co.uk/) ‘High Pressure Mixer Cleaning System’, used for cleaning the inside of the mixer (directly above where the wagons are stationed).

High Pressure Vehicle Washer

The High Pressure Vehicle Washer was reportedly used for

tyre washing purposes. However, as per the photograph shown, it appears to be used as a general vehicle washer (for a portion of the time). There is a sump which collects wash water from this area, but there is no recycling - all water is discharged. The frequency with which this system is used tends to vary directly with the weather.

Dust Suppression Vehicles The number of dust suppression vehicles in use is at its peak during dryer, summer months (around 6/7). There were 3 vehicles on site on the day of the audit.

The mobile dust suppression vehicles use pressure-controlled

hydraulic systems for controlling the water flow rate, allowing the operator to increase/decrease the water output depending on site conditions at the time. The contractor reported that the water for dust suppression is generally abstracted from the Sustainable Urban Drainage System (SUDS) ponds located across the site, minimising the mains water requirement.

Domestic & Welfare Facilities

The main site Compound contains the following facilities:

Toilets (multiple, male and female)

Canteen (including food preparation)

Medical centre (sink contained within)

Kitchens (multiple)

Cleaner’s sink Outwith the main site compound, there are 2 secondary compounds containing lesser domestic/welfare facilities.

57

Area/Application Comment

Hydraulically Bound Material (HBM)

The contractor undertakes treatment of the road surface using HBM Machines. In the first instance, the contractor monitors the moisture content of the road. Using this information, the machine is programmed with the required (if any) volume of water to use in the subsequent treatment process. As the addition of too much (or too little) water would have quality repercussions, this is unlikely to represent an opportunity for water efficiency savings.

Caravan Park

There is extensive Caravan Park on site used for accommodation (mostly contractors). There are around 122 caravans on site at the moment, each of which was in use at the time of the audit (as such, inside of caravans could not be inspected). In addition, the Caravan Park has its own communal domestic and welfare facilities, containing showers and toilets. Since meter readings commenced on 05 March 2010, the Caravan Park has consumed 4,965 m3 of water (which corresponds to around 95.7 m3/week).

Laboratory

There is a laboratory in the main site Compound which contains: Wash Hand Basins (WHBs) Washout Area (pictured left) “Cube Tanks” (used for curing test tubes) The Washout Area is reportedly used for between 1 - 5 hours per day, for rinsing soil/aggregate samples. The Cube Tanks have their water changed once the water visibly becomes fouled (generally around once per month).

Road Sweepers Picture taken from AE Faulks Ltd (Faulks) website:

There are a number of road sweepers used on site, and the one inspected was a Faulks ‘High Capacity Roadsweeper’ - see www.aefaulks.co.uk/ for more details. The driver who was spoken to confirmed that water is only used when required (i.e. when road sufficiently dirty). Additionally, the flow rate of water used is variable (high and low pressure settings), and again is set dependent on the road conditions.

As well as the above, the contractor reported there is a hydro-blasting machine which is sometimes used – this was not on site as the time of the audit.

58

Water Mass Balance Based on the information available at present, the following provisional water mass balance for the site has been prepared:

Distribution Network Weekly Consumption (m3) Percent of Site

Concrete Batching Plant 91.6 31.7

Caravan Park 95.7 33.1

Site Compound - Remainder 61.5 21.3

Stand-pipes 40.1 13.9

TOTAL 288.9 100.0%

In order to expand upon this provisional water mass balance, the contractor may wish to install additional sub-meters within the main site compound. Areas to consider include:

Domestic and Welfare Facilities x 2 (separate meter for the communal Caravan Park facilities)

High Pressure Vehicle Washer

Laboratory

Areas of Opportunity The following table summarises the areas of opportunity for water efficiency actions on site:

Action Water Savings (m3/week)

Replace Concrete Batching Plant Hose 11.5

High Pressure Vehicle Washer - Recycle Wastewater 13.5

Road Sweepers - Recycle Wastewater 4.9

Domestic & Welfare Facilities - Efficiency Improvements 22.75

Monitoring & Targeting 2.9

Rainwater Harvesting 14.7

Total 70.25

As such, it is estimated that the contractor could reduce site water consumption by around 24.3% through implementing

the actions outlined above.

Further details on each action are outlined below.

Replace Concrete Batching Plant Hose

The concrete batching plant utilises a standard mains pressure hose, controlled by a quarter turn isolation valve, for

washing the concrete wagons:

Typically, using standard mains pressure hoses for cleaning applications will be water inefficient - the basic flow pattern

and relatively low pressure are not conducive to efficient cleaning. As such, a trigger-operated high pressure (low flow)

washer is recommended. As well as using less water for cleaning, it will also eliminate the chance of the system being

left operational (i.e. with running water) when not in use.

59

Although there is already a high pressure washer associated with the concrete batching plant, this is for cleaning the

mixers of the concrete batching plant, and it operates with a flow of around 48 lpm. The contractor should look to obtain

a high pressure washer more suited to washing concrete wagons, which should operate with a much reduced flow rate.

Estimated Savings

As the volume flow from the hose and the typical recycling rate of the plant is currently unknown, estimating the

potential savings from this action is difficult. Assuming that the hose accounts for 25% of the water consumption of the

concrete batching plant, and that this can be reduced by 50% through utilising a high pressure washer instead, weekly

savings of around 11.5 m3 could be achieved.

Before implementing this action, the contractor may wish to confirm the current flow rate of the hose (in order to

confirm the potential savings on offer).

High Pressure Vehicle Washer - Recycle Wastewater

There is currently no recycling of the wastewater produced from the High Pressure Vehicle Washer - all wastewater

collects in a sump before passing to drain. The high pressure washer is made by Brendon Powerwashers

(www.powerwashers.co.uk/), model 30KLN + ES, and reportedly consumes around 15 lpm. The water consumed by this

plant will vary depending on how often it is used, which will vary depending on the weather. The following table

summarises the potential weekly consumption for a selection of operational hours:

Operational Hours (hours/week)

Water Requirement (m3/week)

1 0.9

5 4.5

15 13.5

20 18

25 22.5

30 27

40 36

50 45

As such, if a wastewater recycling system is implemented, significant water savings could be achieved.

There are 2 main options open to the contractor to implement a wastewater recycling system. Either the existing system

can be modified to incorporate the necessary changes, or an automatic drive-on wheel washing system (with in-built

recycling of wastewater) can be hired/purchased. As modifying the existing system may result in issues with nozzle

blockage (i.e. recycled wastewater, even if filtered, may block nozzle at end of lance), the latter may be the most

practical option in this instance. As well as reducing the water consumption required for wheel washing, this action

should significantly reduce the time required to undertake the wheel washing activities.

Once this system is installed, it is likely that the contractor could then top-up the system using surface water from some

of the Sustainable Urban Drainage System (SUDS) located across the site, thus completely eliminating the mains water

requirement of the area.

Estimated Savings

Assuming the system is currently used for an average of 15 hours per week, weekly savings of around 13.5 m3 could be

achieved.

Road Sweepers - Recycle Wastewater

A typical industrial road sweeper may use up to 35 lpm of water for dust suppression purposes. The sweeper which was

inspected did not appear to have any form of water recycling system in place. Thus, all wastewater which is collected

(via suction) is stored before discharge. Some manufacturers (and hire companies) offer systems which recycle a portion

of the water. As well as reduced water consumption, this allows the road sweepers to operate for longer periods before

re-filling is required. It is recommended that the contractor utilise road sweepers with water recycling systems

incorporated henceforth.

60

Estimated Savings

Based on discussions with one manufacturer (Johnston Sweepers Ltd), the following information was obtained in relation

to their V650 model (their most popular model):

Based on fresh water spraying on one side into the channel brush dust suppression system and the nozzle dust suppression system, water consumption in the region of 7.2 lpm

Based on fresh water spraying on one side into the channel brush dust suppression and recirculation water into the

nozzle dust suppression system, water consumption in the region of 4.9 lpm

Thus, based on the conditions stated above, the recirculation system may reduce water consumption by around 32%.

Assuming that road sweepers currently account for 25% of the water consumption of the ‘Site Compound – Remainder’

meter, weekly savings of around 4.9 m3 could be achieved.

Domestic & Welfare Facilities - Efficiency Improvements Wash Hand Basins/Sinks

All the Wash Hand Basins (WHBs) and sinks on site appeared to be directly fed from mains, and generally have a

mixture of turn and percussion (i.e. push) mechanisms installed to control their operation. As such, the following

efficiency problems can occur:

Flow from taps will vary directly with mains pressure, and will generally be too high (< 5 litres per minute is good

practice).

Potential for turn taps to be left running for extended period (i.e. no auto-isolation of flow).

Due to basic flow pattern (i.e. no spraying) more water is required for effective cleaning (e.g. hand rinsing).

There are many options open to the contractor to alleviate these problems. In this instance, the following is

recommended:

Each WHB with a flow in excess of 10 litres per minute should have a variable Pressure Reduction Valve (PRV) fitted on the supply pipework. It may be possible to fit a small number of PRVs to control multiple areas, depending

on the configuration of the distribution network. The PRVs will act to set a maximum pressure (and thus volume

flow).

Each WHB with turn control mechanisms should be fitted with percussion equivalents. These act to set a maximum

operating time for each use.

Each sink should be individually assessed, and PRVs and/or percussion-control considered. Where most activities undertaken will require the same volume of water regardless of flow (e.g. filling a kittle) then water efficiency

devices will achieve little improvement. However, where the water requirement is variable (e.g. hand washing) then

water efficiency devices should be considered.

In addition, it was noted that the operating time for a number of the existing percussion taps was excessive. As such,

each percussion tap should be adjusted to give an operating time of around 5 seconds. Where adjustment is not

possible, consideration should be given to replacement of the system.

Toilet Cisterns The toilet cisterns appeared standard size (i.e. ~ 6 - 8 litres), with a single lever flush mechanism, and did not appear to have any water efficiency devices incorporated.

In the first instance, the cistern volumes should be confirmed. Where a cistern volume is 6 litres or less, retro-fitting of water efficiency devices is not recommended. However, where the cistern volume is 7 litres or more, consideration should be given to the installation of Cistern Volume Adjusters (CVAs). CVAs can sometimes be installed inside toilet cisterns to reduce effective flushing volumes (by displacing a portion of the water inside) without adversely affecting performance. Following discussions with the cistern manufacturer(s) to confirm suitability, CVAs should be installed in any cisterns with capacities equal to or above 7 litres.

Although larger (i.e. ~3 litres) CVAs are available, 1 litre ‘Save-A-Flush’ systems are recommended in this instance. More

information can be found at http://www.dry-planet.com/products.html.

61

Estimated Savings

Based on a WRAP typical domestic figure of 40 litres per person per day (for a facility with a canteen, as per Envirowise

Guide GG152 Tracking Water Use to Cut Costs), the daily domestic/welfare water consumption for the site may be

around 26 m3 (based on 650 employees). Assuming 70% of this value is associated with WHBs/sinks and toilet flushing,

and that 25% savings can be achieved, weekly savings of around 22.75 m3 could be achieved.

Monitoring & Targeting

The water use across the site is of sufficient magnitude to merit a Monitoring and Targeting (M&T) system. In the first

instance, KPIs should be created for each area within the main site compound. Examples of the KPIs which could be

used are:

Concrete Batching Plant: m3 of water per m3 cement produced

Caravan Park: m3 of water per permanent resident

Site Compound - Remainder: m3 of water per average staff number over monitoring period

These should be recorded regularly (e.g. monthly) and assessed for any erroneous consumptions, etc. The contractor

may also benefit from undertaking brief out-of-hours baseload assessments on each meter to confirm there are no leaks

or unnecessary uses.

Estimated Savings

Estimating the savings from such an action is difficult - based on an arbitrary figure of 1% of the site’s water

consumption, savings may be in the region of 2.9 m3/week.

Rainwater Harvesting

The H-Block in the main site compound has a roof area of around 1,749 m2, which may allow collection of rainwater for

re-use elsewhere in the site. A limited rainwater harvesting study has been undertaken to estimate how much water

could potentially be collected.

The following information has been used to undertake this analysis:

Parameter Value Comment

Roof Area 1,749 m2 Estimated total roof area of H-Block.

Drainage Co-efficient (or

Run-off Factor) 0.8

Value for ‘flat roof with gravel layer’, as per Environment Agency’s:

Harvesting Rainwater for Domestic Uses: an Information Guide

Filter Efficiency 0.9 Typical value, as per Environment Agency’s: Harvesting Rainwater for

Domestic Uses: an Information Guide

Rainfall Data See table below Data taken from Met Office website for Sutton Bonington (1971 -

2000 average)

Using this information, the following calculations can be undertaken:

Month Rainfall (mm)

Collectable Volume (m3)

January 55 69

February 43 54

March 45 57

April 47 59

May 42 53

June 61 77

July 44 55

August 51 64

September 53 66

October 54 68

November 53 67

December 59 75

ANNUAL 606.2 763

62

As such, around 14.7 m3/week (average figure) of water could be collected for re-use by rainwater harvesting. There are

a number of potential areas where this water could be used, including:

Hosing water around Concrete Batching Plant

High Pressure Vehicle Washer

Toilet Flushing

Laboratory Washout Area

Estimated Savings

Assuming all collected water can be re-used, weekly savings of around 14.7 m3/week may be possible.

63

Appendix 4 Site 4: Commercial Retail (Department Store) Site

Introduction Site 4, located in England, was audited on Monday 07 March 2011. The following information applies to the project:

Value of Site (contractors output) Phase 1 (i.e. Building Shell): £26,000,000 Phase 2 (i.e. Fit-out): £23,000,000 Total Value: £49,000,000

Footprint Area of Site (m2) 16,722

Typical Site Working Hours

Monday - Friday: 08:00 - 17:00

Saturday: 08:00 - 13:00 (only sometimes)

Sunday: N/A

Maximum Number of People on Site ~ 70

Phase of Construction Construction of building shell

Classification Commercial Retail

Project Use Class Department Store

Project Type New Build

Construction Type Steel Frame & Timber Frame

Client Type Retail Company

Contractual Agreement Individual Company

The bulk of the contractor’s site work commenced on 04 October 2010 (though a sub-contractor was on site in September 2010), and it is planned that Phase 1 of the project (i.e. construction of building shell) will last for around 65 weeks from this date. Phase 2 (i.e. building fit-out) is to commence in May 2012. At present, the minimum amount of people on site is around 40, with 70 being the maximum. These numbers increase for Phase 2, where it is estimated there will be between 100 - 160 on site. The main building is to be steel and timber frame, and the car park will be concrete-based.

Water Supply Initially, water was provided to the site via water bowsers, delivered as and when required. On 18 October 2010, a mains water supply was installed. There have been no water bowsers delivered to the site since 25 November 2010. The contractor reports that they paid £45 per week for the hire of a 2,700 litre bowser, as well £120 for each filling (i.e. 44.4 £/m3). A bill for the mains water supply has yet to be received, and so no billing details are available at this time. At present, there is no water distribution network out with the main office/welfare/domestic facilities.

64

Site Water Consumption The site initially used water delivered in bowsers, and the following chart shows how the Specific Water Consumption

(SWC) varied over time:

In total, 16.15 m3 of water was delivered to site over a period of 71 days (i.e. 10.1 weeks), giving an average bowser SWC of 1.6 m3/week. Once the mains water meter was installed, the water consumed on site increased significantly (as expected) – the following chart shows how the mains water SWC has varied:

In total, 89.56 m3 of mains water has been used by the site (up until 07 March 2011) over a period of 140 days (i.e. 20 weeks), giving an average SWC of 4.5 m3/week. The noticeable rise in water consumption at the beginning of 2011 is reportedly due to the directional drilling which took place (and which has since ceased). Since records began on 15 September 2010, the site has consumed 105.71 m3 of water over a period of 173 days (i.e. 24.7 weeks), giving an average SWC of 4.3 m3/week.

Assuming the average mains water SWC of 4.5 m3/week continues until completion of Phase 1 of the project (assumed end date taken as 02 January 2012), a further 192.56 m3 of water will be consumed by the site. Based on this data, the total water consumption of Phase 1 will be 298.27 m3. Using the Phase 1 contract value noted above, the Current Price Strategic Forum Key Performance Indicator (KPI) for the project would be around:

11.5 m3/£million contractors output

65

Water Consuming Areas/Applications The following table summarises the main water using areas/applications on site:

Area/Application Comment

Water Meter

Water meter was installed on 18 October 2010.

Wheel Wash Area

Settlement Tank

There is a drive-on Wheel Wash located at the entrance to the site, which was not in use on the day of the audit (due to good weather). Adjacent to the Wheel Wash is the settlement tank, where the used wash water is recycled to. When required, this tank is topped-up using water from a nearby Sustainable Urban Drainage System (SUDS). As such, the system generally has no mains water requirement. The system is a Rhino Compact (by Wheel Wash Cleaning Solutions), further details of which can be found at: http://www.wheelwash.co.uk/Rhino_Compact.htm

The following information was contained within the Operating & Maintenance (O&M) Manual: 9.4 kW centrifugal wash pump (delivery 760 lpm at

pump pressure of 3 bar) 5.2 kW waste return pump (handling up to 1,440 lpm) 15,000 litres settlement tank Main wash cycle lasts 20 seconds Total wash cycle time, including wash down - 50 seconds The contractor reports that every construction vehicle exiting the site will use the Wheel Wash, when weather requires it - the number of vehicles has been estimated at 10 per hour.

Domestic and welfare facilities

The site contains the following water using areas/applications: Toilets Canteen (self-catering) Showers Kitchen

66

Area/Application Comment

Road Sweeper [NO PHOTOGRAPH]

The site uses a road sweeper when weather requires it, but this was not in use (or on site) on the day of the audit (due to good weather). Reportedly, the road sweeper (which is operated by an external contractor) is used between the hours of 08:00 - 16:00 when required. The contractor has estimated that the maximum volume of water they would use is 1,000 litres per day. When in use, the road sweeper is filled with water prior to arrival at site, and so should not account for any of the site’s mains water use.

Mortar [NO PHOTOGRAPH]

At present, the brick-layers have ready-to-use mortar brought to site, and so this will not account for any of the site’s mains water consumption. At a later stage of the project, dry-mortar silos may be installed on site.

No other current water consuming areas/activities were reported by the contractor, or noted during the site audit. The

following were reportedly undertaken previously, or will be undertaken at a future stage of the project:

Directional drilling

Dust suppression

Cleaning operations at project end

Plastering

Tiling

Rendering

Soak test of roof

Mechanical and Electrical (M&E) Plant/Equipment - Testing and Commissioning

Landscaping (e.g. watering plants)

Water Mass Balance

Based on the information collected on the day of the site audit, the only significant mains water requirement at present

is the domestic and welfare facilities. Using the previous three meter readings, the current average SWC of the site is

5.50 m3/week.

Areas of Opportunity The following table summarises the areas of opportunity water efficiency actions for the site:

Action Water Savings

(m3/week)

Domestic & Welfare Facilities - Efficiency Improvements 0.96

Monitoring & Targeting 0.06

Total 1.02

As such, it is estimated that the contractor could reduce site water consumption by around 18.5%.

Further details on each action is outlined below.

67

Domestic & Welfare Facilities - Efficiency Improvements Wash Hand Basins/Sinks All the Wash Hand Basins (WHBs) and sinks on site appeared to be directly fed from mains (for cold taps), and generally have a mixture of turn and percussion (i.e. push) mechanisms installed to control their operation. As such, the following efficiency problems can occur:

Cold flow from taps will vary directly with mains pressure, and will generally be too high (< 5 litres per minute is

good practice).

Potential for turn taps to be left running for extended period (i.e. no auto-isolation of flow).

Due to basic flow pattern (i.e. no spraying) more water is required for effective cleaning (e.g. hand rinsing).

In the first instance, the flow rates from a number of taps were monitored to provide a greater understanding of the potential for water savings - the following table summarises the findings:

Area Application

Cold -

Volume Flow (lpm)

Hot -

Volume Flow (lpm)

Good Flow (lpm)

Fair Flow (lpm)

Poor Flow (lpm)

Comment

Male Toilet (Office)

WHB 11.3 8.6

<5 5 - 10 >10

Fair - Poor performance achieved.

Kitchen Sink 11.8 8.6 Fair - Poor performance achieved.

Canteen 1 Sink 10.2 Didn’t

monitor Poor performance achieved.

Canteen 2 Sink 12.6 8.1 Fair - Poor performance achieved

Male Toilets WHB

(1 of 4) 10.1 9.0

Fair - Poor performance achieved

Male Toilets WHB

(2 of 4) 10.5 11.4 Poor performance achieved.

As such, it can be seen that every cold outlet is performing poorly and represents an opportunity for savings. Also, it was noted that the percussion mechanisms in some areas have excessive operating times. For example, the Canteen 2 sink remains operational for around 18 seconds after activation, and the Male Toilet for between 10 - 19 seconds (for the 2 WHBs which were assessed). The following improvements are recommended:

Percussion mechanisms fitted to cold taps which do not currently have them fitted.

Adjust (or replace) percussion mechanisms with excessive operating times.

Install Pressure Reduction Valve (PRVs) to reduce operating pressure to cold taps.

This will ensure a maximum distribution pressure and/or operating time, thus minimising wastage. Note - if the contractor is convinced that most activities in the canteens/kitchen will use the same volume of water independent of flow (e.g. filling a kettle), then installation of PRVs is not recommended - this is only recommended where volume is not independent of flow (e.g. hand washing, glass rinsing, etc.). Toilet Cisterns The toilet cisterns appeared standard size (i.e. ~ 6 - 8 litres), with a single lever flush mechanism, and did not appear to have any water efficiency devices incorporated. In the first instance, the cistern volumes should be confirmed. Where a cistern volume is 6 litres or less, retro-fitting of water efficiency devices is not recommended. However, where the cistern volume is 7 litres or more, consideration should be given to the installation of Cistern Volume Adjusters (CVAs). CVAs can sometimes be installed inside toilet cisterns to reduce effective flushing volumes (by displacing a portion of the water inside) without adversely affecting performance. Following discussions with the cistern manufacturer(s) to confirm suitability, CVAs should be installed in any cisterns with capacities equal to or above 7 litres.

Although larger (i.e. ~3 litres) CVAs are available, 1 litre ‘Save-A-Flush’ systems are recommended in this instance. More

information can be found at http://www.dry-planet.com/products.html.

68

Estimated Savings

Assuming 70% of current SWC is associated with WHBs/sinks and toilet flushing, and that 25% savings can be achieved,

weekly savings of around 0.96 m3 could be achieved.

Monitoring & Targeting

It is recommended that the contractor implements a simple Monitoring & Targeting (M&T) system for the site’s water

consumption - this will involve undertaking two main actions on a regular basis:

Track water consumed (m3) per week, and assess for erroneous consumption.

Once per month, conduct brief out-of-hours assessment of baseload water consumption.

The contractor may wish to develop a KPI for water, relating it to a factor such as average persons on site for the

monitoring period - as a significant portion of the water consumption is associated with domestic/welfare, this should

prove a useful analysis.

These actions should help identify (and eliminate) unnecessary water consumption on site.

Estimated Savings

Estimating the savings from such an action is difficult, and will vary from site to site - in this instance an arbitrary figure

of 1% of the current site water consumption will be used - this accounts to around 0.06 m3/week.

69

Appendix 5 Site 5: Leisure (Sports Hall/Centre) Venue

Introduction Site 5, located in Scotland, was audited on Friday 11 March 2011. The following information applies to the project:

Value of Site (contractors output) £93,000,000

Footprint Area of Site (m2) 105,000

Typical Site Working Hours

Monday - Friday: 08:00 - 17:30 (can experience variation)

Saturday: 08:00 - 16:00 (can experience variation)

Sunday: 09:00 - 12:00 (only worked rarely)

Maximum Number of People on Site ~ 300

Phase of Construction

Building 1:

Ongoing steelwork Ongoing installation of suspended gantries Perimeter blockwork and windposts Curtain walling Cladding and louvres High level ductwork Some internal blockwork Installation of M&E

Building 2:

Ongoing concrete works to terraces & walls, slabs and pits Roof installation Perimeter blockwork Syphonic drainage installation Installation of precast wall panels Curtain walling Installation of insulated Trimo-Raster panels Cladding High level ductwork M&E installation

Sports Halls:

Casting remainder slab Cladding Roofworks Blockwork Syphonic drainage installation

Hub:

Roof fit-out Installation of roof plant M&E installations Installation of precast walls

External Works:

Temporary opening to external Road

Classification Leisure

Project Use Class Sports Hall/Centre

Project Type New build

Construction Type Steel Frame (Building 1 & Building 2) Concrete Frame (Hub)

Client Type Local Government

Contractual Agreement Individual Company

70

The contractor was first on site in October 2009, with the project officially commencing in January 2010. The project was

split into two distinct stages - Stage 1 primarily involved sub-structure and excavation work, and was concluded around

July 2010. Stage 2 is due to run until project completion, currently estimated at April 2012. Although the Project Type is

listed as ‘new build’ above, remediation work was undertaken prior to the contractor’s involvement in the project.

There were 286 employees on site on the day of the audit, near to the maximum figure. The contractor reports there

have been less than this during previous phases of the project.

Water Supply

There is one Scottish Water/Business Stream meter which serves the site. The contractor paid a single up-front payment

to have this meter installed, and does not experience any operating costs (i.e. they are not charged for water on a

volumetric consumption basis) - this is likely to be the main barrier to implementing water efficiency actions on site (i.e.

there is no financial reward for improvement). The contractor was unwilling to divulge the value of the up-front

payment, noting it to be “sensitive information”.

A detailed water schematic for the site does not currently exist. As well as the water supply to the office/welfare areas

and the Wheel Wash, there appears to be 2 further draw-off points, each of which is associated with mortar silos.

Site Water Consumption

The following meter readings were provided or taken during the site audit:

Date Reading (m3) Average Consumption since Previous

Reading (m3/week)

29 January 2010 0 N/A

28 October 2010 5,578 142.8

11 March 2011 at 09:00 13,443 408.1

11 March 2011 at 16:10 13,467 N/A

Based on the meter readings above, the consumption between 09:00 and 16:10 on the day of the audit was 24 m3.

Extrapolating this up for a full 9.5 hour working day, the daily consumption may have been around 31.8 m3 per day

(during normal working hours).

The average weekly consumption since the meter was installed is ~231.7 m3 per week, but is currently 408.1 m³ per

week. Assuming the project runs until 15 April 2012, and the average consumption remains at this level for the duration

of the project, then the total water consumed by the site at project-end will stand at around 26,769 m3. Based on the

value of the site as noted above, the Current Price Strategic Forum Key Performance Indicator (KPI) for the project

would be around:

288.0 m3/£million contractors output

Water Consuming Areas/Applications

The following table summarises the main water using areas/applications on site:

Area/Application Comment

Scottish Water/Business Stream Meter

The Scottish Water/Business Stream meter is located adjacent (externally) to the site boundary. Note that the meter is currently submerged in water.

71

Area/Application Comment

Domestic and Welfare Facilities

The site contains the following water using areas/applications:

Toilets

Canteen (self-catering and preparation kitchen)

Showers

Kitchen

Wheel Wash

The drive-on Wheel Wash is used by vehicles as they exit the

site via the delivery entrance. The water settlement tank associated with the Wheel Wash (located behind the main wheel washing area shown in the picture) is topped up via flexible plastic piping which rises from the ground.

Mortar Silos

There are twin mortar silos next to the delivery entrance (pictured left), and one further mortar silo at the back (i.e. North-East) end of the site. As well as the water feed to the silos themselves, each area has an individual water draw-off point. The mortar silos are CPI Euro-mix - further information on the units can be found at: http://www.euromix.com/ The draw-off points adjacent to each silo will be used for some of the smaller, miscellaneous water requirements associated with construction sites. During the audit, the only use of these draw-off points which was observed was the filling of an Intermediate Bulk Container (IBC), which was to be used in association with coring holes in stairs.

High Pressure Washer

The high-pressure washer was located on site during the audit. However, it was not currently in use and the contractor was unable to advise what its intended purpose was. The unit was manufactured by Brendon Bowsers, and further information on their products can be found at:

http://www.powerwashers.co.uk/

72

No other current water consuming areas/activities were reported by the contractor, or noted during the site audit. The following were reportedly undertaken previously, or will be undertaken at a future stage of the project:

Dust suppression for stone-cutting.

Agricultural use (e.g. watering plants).

Plant commissioning.

Plant (e.g. ductwork) cleaning.

It was decided that the wheel wash (as a high priority activity) would be investigated further. Following initial investigation of the system, it was clear that it accounted for a significant portion of the site water consumption. As such, the water feed to this area was monitored (using a clamp-on ultrasonic flow meter) to allow quantification of the consumption - the results, in chart form, are shown below:

The average consumption over the monitoring period was 2.2 m3 per hour. Thus, the weekly consumption (based on a 55.5 hour working week) is around 122.1 m3 which is a significant portion of the site water use (approximately 29.9 % based on the numbers current site water consumption noted above).

Water Mass Balance Based on the information available at present, the following provisional water mass balance for the site has been prepared:

Activity Water Use (m3/week)

Wheel Wash 122.1

Potential Leak 265.3

Domestic 63.4

Unquantified (Domestic Use, Mortar Make-up, etc.) Unknown

Total >450.8

This information is based on the current level of water consumption on site, and not the average since the project commenced.

Areas of Opportunity The following table summarises the areas of opportunity water efficiency actions for the site:

Action Water Savings

(m3/week)

Wheel Wash - Efficiency Improvements 91.6

Domestic & Welfare Facilities - Efficiency Improvements 11.1

Leak Investigation & Repair 265.3

Additional Considerations 4.1

TOTAL 372.1

As such, it is estimated that the contractor could reduce site water consumption by around 82.5%.

73

Further details on each of the actions is outlined below:

Wheel Wash - Efficiency Improvements

The water top-up to the Wheel Wash is uncontrolled - there is an open hose feeding the storage tank which runs

constantly:

The contractor reports this supply is switched on/off at the start/end of each working day.

Once this storage tank is full, the water over-flows from a discharge pipe at the rear of the unit (tank not over-flowing at

time of picture):

Thus, the unit is discharging suitable quality water to the ground for a significant portion of the time it is operational.

The amount of water being discharged to the ground will depend on how often the Wheel Wash is used.

In addition to the uncontrolled top-up mechanism, the water pump remains on for a few seconds after a vehicle is

finished washing. In this short period a large volume of water is sprayed outwards beyond the catchment system.

In the first instance, a ball float-valve should be installed to control the top-up to the storage vessel. This simple device

will stop the water topping-up when the tank is already full, eliminating unnecessary over-flow.

Secondly, the contractor may wish to consider the installation of an optical sensor to sense when a vehicle is no longer

above the spray nozzles. This sensor could then isolate the power supply to the pump, minimising water wastage at the

end of wash.

74

Shown below are the spray nozzles following a wash (and after pump has been deactivated):

The contractor may also wish to consider whether the current water pressure is required, or if it can be reduced without

adversely affecting the cleaning performance. If the water pressure can be reduced, the volume of water used per wash,

and potentially the volume of water which is captured for recycling, will improve. This could be achieved in a number of

ways, such as:

Install a variable Pressure Reduction Valve (PRV) on the pipework feeding the spray nozzles.

Fit a Variable Speed Drive (VSD) on the existing pump.

Replace the existing pump with a smaller equivalent. The following graph shows how a reduction in water pressure will affect the flow rate from the nozzles:

Estimated Savings There is the potential for significant savings at the Wheel Wash, though the magnitude of savings are difficult to estimate as they will vary with a number of factors. Assuming a 75% reduction in the average water consumption can be achieved, savings of around 91.6 m3/week could be achieved - this corresponds to around 22.4% of site water consumption.

75

Domestic & Welfare Facilities - Efficiency Improvements Wash Hand Basins/Sinks All the Wash Hand Basins (WHBs) and sinks on site are directly fed from mains, and generally have turn-mechanisms to control the cold outlets:

There are a number of efficiency problems with this sort of system, including:

Flow from tap will vary directly with mains pressure, and will generally be too high (< 5 litres per minute is good practice).

Potential for taps to be left running for extended period (i.e. no auto-isolation of flow).

Due to basic flow pattern (i.e. no spraying) more water is required for effective cleaning.

In addition, once the contractor resolves the issue with the inefficient Wheel Wash and the potential leak, it is likely that the available water pressure all across the site (and thus flow from taps) will increase significantly.

There are a number of options open to the contractor to resolve this situation. In this instance, the following is

recommended:

Installation of PRVs on the water supply pipework to each cabin.

Replace existing taps with percussion-controlled (i.e. push) equivalent (WHBs only).

This will ensure a maximum distribution pressure and operating time, thus minimising wastage.

Toilet Cisterns

The toilet cisterns appeared standard size (i.e. ~ 6 - 8 litres), with a single lever flush mechanism, and did not appear to

have any water efficiency devices incorporated:

76

In the first instance, the cistern volumes should be confirmed. Where a cistern volume is 6 litres or less, retro-fitting of

water efficiency devices is not recommended. However, where the cistern volume is 7 litres or more, consideration

should be given to the installation of Cistern Volume Adjusters (CVAs). CVAs can sometimes be installed inside toilet

cisterns to reduce effective flushing volumes (by displacing a portion of the water inside) without adversely affecting

performance. Following discussions with the cistern manufacturer(s) to confirm suitability, CVAs should be installed in

any cisterns with capacities equal to or above 7 litres.

Although larger (i.e. ~3 litres) CVAs are available, 1 litre ‘Save-A-Flush’ systems are recommended in this instance. More

information can be found at http://www.dry-planet.com/products.html.

Estimated Savings

Based on a WRAP typical domestic figure of 40 litres per person per day (for a facility with a canteen), the annual

domestic/welfare water consumption for the site (based on 286 employees) is around 3,295 m3. Assuming 70% of this

value is associated with WHBs/sinks and toilet flushing, and that 25% savings can be achieved, annual savings of around

577 m3 could be achieved. This corresponds to weekly savings of 11.1 m3.

Leak Investigation & Repair

A final meter reading was taken at the end of the site audit day (i.e. 16:10 on a Friday). At this time, it appeared that all

construction work had ceased for the day, and only security staff remained on site. However, it was noted that the visual

dial on the meter was still turning relatively quickly, suggesting a significant water volume was still passing through the

meter. As such, it appears there may be a leak downstream of the meter, and there are a number of facts which support

this theory:

Average site water consumption between 28 October 2010 - 11 March 2011 is almost 3 times the average site

water consumption between 29 January 2010 - 28 March 2010.

Winter 2010/2011 was one of the coldest on record, increasing the chances of a burst pipe.

Water meter is fully submerged in water.

Work being undertaken on gas pipework adjacent to water meter for a period of months (meter has only recently

become accessible again), may have resulted in damage to water pipework.

There are potential alternative explanations to all the above points, but considering them all together there is a strong

argument for a leak. As such, it is recommended that the contractor:

Confirm the presence and magnitude of the erroneous water consumption by monitoring the meter for a sustained

period (e.g. half-hour) out with operating hours.

Investigate all major water using areas on site and confirm there is no known water consumption(s).

Undertake leak detection and repair work.

Estimated Savings

There is not currently enough information to estimate the savings associated with this action, although by undertaking a

brief out-of-hours analysis of the main water meter it can be confirmed relatively quickly. Assuming that the leak is the

primary reason for the large increase in site water consumption from 142.8 m3 to 408.1 m3/week, then savings of up to

265.3 m3/week could potentially be achieved.

Additional Considerations

Monitoring & Targeting

It is recommended that the contractor implement a simple Monitoring and Targeting (M&T) system for the site’s water

consumption - this will involve undertaking two main actions on a regular basis:

Track water consumed (m3) per week, and assess for erroneous consumption.

Once per month, conduct brief out-of-hours assessment of baseload water consumption.

The actions should help identify (and eliminate) unnecessary water consumption on site (such as the potential leak

outlined above).

77

It is noted that the water meter has only recently become accessible again after a period of several months, due to

extended work being undertaken on gas pipework next the meter.

Trigger-operated Control

The draw-off points adjacent to the silos were not trigger spray-gun operated:

Although these were not observed to be leading to inefficiencies, general good practice suggests trigger-operated spray-

gun control should be installed.

Maintenance

As a consequence of constantly moving location, flexible water pipework on construction sites can be prone to minor

damage resulting in leaks (as per the following pipe associated with the Wheel Wash):

The contractor should ensure all water pipework is maintained regularly, and any leaks (such as that pictured above) are

repaired once observed.

Estimated Savings

There is not currently enough information to estimate the savings associated with these actions, and as such an arbitrary

figure of 1% of the current site water consumption (current site water consumption taken as average consumption since

previous meter read in this instance i.e. 408.1 m3/week) will be used - this accounts to 4.1 m3/week.

78

Appendix 6 Site 6: Civil Engineering (Road) Site

Introduction Site 6, located in Scotland, was audited on Monday 14 March 2011. The following information applies to the project:

Value of Site (contractors output) £445,000,000

Length of Scheme 8.5 km

Typical Site Working Hours

Monday - Friday: 07:30 - 18:00

Saturday: 07:00 - 13:00

Sunday: N/A

Maximum Number of People on Site 900

Phase of Construction The project commenced in May 2008, and will run until June

2011.

Classification Civil Engineering

Project Use Class Road

Project Type New Build

Construction Type Civil Engineering

Client Type Local Government

Contractual Agreement Joint Venture

Most of the new road lies on previously derelict land.

Water Supply

As well as the main site Compound, there are various other operations located across the site. These include:

West Section Office

East Section Office

Batching Plant

3 x Domestic and Welfare Facilities

Each area appeared to have a mains water supply except one of the domestic and welfare facilities, which had a water

storage tank which is regularly filled with water from a bowser (which in turn is filled with water from a stand-pipe).

There are 3 stand-pipes which serve the site, and the contractor reports that almost all of the stand-pipe water will be

taken from 1 of these standpipes alone. The contractor also has a CAR Licence to allow abstraction of water from a

nearby watercourse. The licence allows abstraction of up to 50 m3/day of water, and this water is typically used for dust

suppression and wheel washing purposes. It is reported that, generally, operations on the East-side of the site will

abstract from the watercourse, whereas operations in the West-side of the site will utilise the primary standpipe.

A detailed water schematic for the site does not currently exist.

Site Water Consumption

The management of water consumption across the site is varied - some pertinent points are noted below:

The only mains water supply which the contractor currently pays for is the West Section Office. All other

buildings/areas are currently considered unoccupied/unused by Scottish Water/Business Stream.

Up-front charges were paid for stand-pipe installation (£1,006.72 including VAT for 2 of the stand-pipes combined).

There are no on-going charges.

Surface water abstraction volumes are not recorded.

As such, the current level of water-based information which is recorded does not allow accurate quantification of the

site’s water consumption. This lack of consumption data, combined with the relatively small percentage of water which is

paid for based on actual consumption (on a £/m3 basis), will likely act as the main barrier to implementing water

efficiency improvements across the site.

79

West Section Office

The West Section Office was initially considered unoccupied by Scottish Water/Business Stream, for around 2 years at

the start of the project. After this mistake was realised, an initial bill for this period (including back-dated charges) was

provided to the contractor. The following table summarises the information which is currently known, including the

Specific Water Consumption (SWC) for each billing period:

Period Start Period End Days Weeks Consumption

(m3) SWC

(m3/week)

22/06/2008 02/07/2010 740 105.7 1,569 14.8

02/07/2010 18/10/2010 108 15.4 243 15.8

19/10/2010 12/01/2011 85 12.1 147 12.1

TOTAL 933 133.2 1,959 14.70

The SWC variation is shown below, in chart form:

Assuming a project duration of mid-May 2008 until mid-June 2011 (i.e. 1,126 days or 160.9 weeks), and that the

average SWC of 14.70 m3/week is consistent over this period, the West Section Office may consume 2,364 m3 over the

duration of the project.

Offices Water Consumption

The contractor has estimated the following split in office staffing numbers:

Main Site Compound (40%)

West Section Office (40%)

East Section Office (20%)

Based on this information, a basic estimation of water consumption at the remaining two offices can be undertaken.

Assuming the average SWC at the main site Compound is the same as the West Section Office, and the average SWC at

the East Section Office is half that of the West Section Office, the water consumption at each area can be estimated as

follows:

Office SWC (m3/week) Total Consumption (m3)

West Section Office 14.70 2,364

Main Site Compound 14.70 2,364

East Section Office 7.35 1,182

TOTAL 36.75 5,910

80

Water Consuming Areas/Applications The following table summarises the main water using areas/applications on site:

Area/Application Comment

Batching Plant

The Batching Plant produces Stone Mastic Asphalt (SMA), controlled to strict quality requirements. It is an intensive water using area, with most water being used as an ingredient for the SMA. There is also a high pressure washer associated with the plant. There is a flow meter associated with the ingredient water, and as such water used for this purpose can be accurately quantified - the following summary table provides some recent consumption figures (for 2011):

Week Ending Consumption (m3/week)

06 February 29.480

13 February 0.520

20 February 0.000

27 February 14.900

06 March 67.880

13 March 39.290

The average weekly consumption, based on the information above, is 25.345 m3. It has been estimated by the plant operator that the high pressure washer may use around 500 litres per week.

Dust Suppression Vehicles There was no vehicular dust suppression on the day of the site audit, due to the wet weather. However, 1 system was inspected at the main site Compound (i.e. Dust Suppression Vehicle 1), and the contractor provided photographs of a further 2 in operation in 2009 (Dust Suppression Vehicles 2 & 3). Dust Suppression Vehicle 1:

Dust Suppression Vehicle 1 consisted of a tractor connected

to a water bowser, which had a water cannon located at its rear. The cannon directs pumped water off a splash plate to create a spray effect. Dust Suppression Vehicle 2 had a high-level water cannon (i.e. rain gun), which sprays a high velocity pumped water jet upwards from the rear of the bowser (this can be seen in the adjacent photograph). There is also a second water cannon and splash plate at low-level, similar to that associated with Dust Suppression 1. This does not appear to be operating at the time of the photograph. Dust Suppression Vehicle 3 appeared to be similar in operation to Dust Suppression Vehicle 1.

The contractor reported some (or all) of these systems are hired from Ace Plant - more information on Ace Plant’s dust suppression systems can be found at: http://ace-parts.co.uk/dust-suppression/dust-suppression-units.html

81

Area/Application Comment

Dust Suppression Vehicle 2:

Dust Suppression Vehicle 3:

Wheel Wash Systems

There are around 6 wheel wash systems located around the site, which are reportedly bought or hired from Wheel Wash Wheel Cleaning Solutions. The systems which were located were Rhino Multis, more information on which can be found at: http://www.wheelwash.co.uk/Rhino_Multi.htm There was no operational wheel washing on the day of the audit (systems were dismantled).

Road Sweepers

Road sweepers were in operation on the day of the audit, and one driver/operator was spoken to. He advised he fills his water storage tank using his own stand-pipe, not one of the contractor’s. At most, it is filled twice per day. The control system allows operation at low or high pressure, and generally low pressure is sufficient (unless roads are particularly dirty). The contractor reports these systems are generally hired.

82

Area/Application Comment

Pressure Washer

This GAP Group Plant & Tool Hire (http://www.gap-group.co.uk/) Pressure Washer is used for miscellaneous washing of plant. It was not being used on the day of the audit, and the contractor reports is not being used much during this phase of the project.

Domestic and welfare facilities

The site domestic and welfare facilities included:

Toilets

Canteens (self-catering)

Showers

Kitchens

No other current water consuming areas/activities were reported by the contractor, or noted during the site audit. The following were reportedly undertaken previously, or will be undertaken at a future stage of the project:

Concrete batching plant

Dust suppression for stone crushing

Water Mass Balance Based on the information available at present, the following provisional water mass balance for the site has been prepared:

Activity Water Use (m3/week)

West Section Office 14.70

Main Site Compound 14.70

East Section Office 7.35

Batching Plant 25.345

Domestic and Welfare Facility A Unknown

Domestic and Welfare Facility B Unknown

Stand-pipe A Unknown

Stand-pipe B Unknown

Stand-pipe C Unknown

Total Unknown

In order to improve the coverage and accuracy of the water mass balance, improved monitoring of existing meters as well as installation of additional sub-meters, is recommended.

83

Areas of Opportunity

The following table summarises the areas of opportunity water efficiency actions for the site:

Action Water Savings

(m3/week)

Domestic and Welfare - Efficiency Improvements 9.2

Dust Suppression Vehicles - Reduce Mains Water Requirement 318.9

Monitoring & Targeting 3.4

TOTAL 331.5

Further details on each of these actions are outlined below:

Domestic and Welfare - Efficiency Improvements

Wash Hand Basins/Sinks

Most of the Wash Hand Basins (WHBs) and sinks on site are directly fed from mains (cold taps only), are operated using

twist/tap mechanisms and have simple flow patterns (i.e. no spray-head attachment). There are a number of efficiency

problems with these types of systems, including:

Flow from taps will vary directly with mains pressure, and will generally be too high (< 5 litres per minute is good

practice).

Potential for taps to be left running for extended period (i.e. no auto-isolation of flow).

Due to basic flow pattern (i.e. no spraying) more water is required for effective cleaning.

There are a number of options open to the contractor to resolve this situation. In this instance, the following is

recommended:

Reduce the maximum operating pressure of mains cold water by installing variable Pressure Reduction Valves

(PRVs) at strategic points throughout the various distribution networks.

Where twist/turn mechanisms are in use, replace with percussion (i.e. push) equivalent. This is generally applicable

to WHBs, and sometimes applicable to sinks. If most sink activities will use the same volume independent of flow

(i.e. filling a kettle), then the benefits of PRV installation will be reduced.

This will ensure a maximum distribution pressure and operating time, thus minimising wastage.

Also, it was noted that some of the existing percussion taps had excessive operating times. Where possible, the

operating times should be adjusted. Where this is not possible, the taps should be replaced.

Toilet Cisterns

The toilet cisterns appeared standard size (i.e. ~ 6 - 8 litres), with a single lever flush mechanism, and did not appear to

have any water efficiency devices incorporated:

In the first instance, the cistern volumes should be confirmed. Where a cistern volume is 6 litres or less, retro-fitting of

water efficiency devices is not recommended. However, where the cistern volume is 7 litres or more, consideration

should be given to the installation of Cistern Volume Adjusters (CVAs). CVAs can sometimes be installed inside toilet

cisterns to reduce effective flushing volumes (by displacing a portion of the water inside) without adversely affecting

performance. Following discussions with the cistern manufacturer(s) to confirm suitability, CVAs should be installed in

any cisterns with capacities equal to or above 7 litres.

Although larger (i.e. ~3 litres) CVAs are available, 1 litre ‘Save-A-Flush’ systems are recommended in this instance. More

information can be found at http://www.dry-planet.com/products.html.

84

Urinal Cisterns A mixture of good and bad practice was observed in relation to urinal flushing. An example of good practice (i.e. use of a hydraulic valve to control flushing based on occupancy):

A hydraulic valve has been fitted to the inlet pipework of the urinal system. When the inlet water pressure decreases temporarily through water being used elsewhere in the washroom (e.g. toilet flushing or hand washing), the diaphragm-operated valve opens, allowing a pre-set amount of water to pass to the urinal cistern. When the cistern is full, the auto-siphon will discharge and flush the urinal. When the washroom is not being used, the pressure remains unchanged and the valve remains closed. Thus, the cisterns should not use water out with working hours. An example of bad practice (i.e. constant filling and flushing, regardless of occupancy):

In this system, the urinal cistern will constantly fill and flush regardless of occupancy. As such, it may consume more water than is required during the day, and will definitely consume more water than is required out with working hours. It is recommended that hydraulic valves are fitted to each area where urinal flushing is currently uncontrolled, and where the water distribution network allows effective operation of such a system. In the more permanent building structures (e.g. the mains offices) Passive Infra-Red (PIR) motion sensors may be more suitable. Estimated Savings Assuming that domestic and welfare water consumption can be reduced by around 25% through implementing the actions outlined above, savings of around 9.2 m3/week could be achieved. The water consumption of the 3 main offices only has been considered, and as there are additional facilities out with these areas actual savings could be higher.

Dust Suppression Vehicles - Reduce Mains Water Requirement The dust suppression vehicles used at the moment are basic in their operation (i.e. splash plate and rain gun systems), and there is the potential for achieving a significant reduction in dust suppression water consumption through using

more advanced technology. However, before this is considered, the contractor should consider whether the percentage of dust suppression water which is non-mains (i.e. abstracted from surface water or from Sustainable Urban Drainage Systems (SUDS)) can be increased.

85

At present, water for dust suppression comes from a mixture of stand-pipe and surface water abstraction. There is currently no use of SUDS water for this purpose. Due to the low quality requirement of dust suppression water, all non-mains water sources should be considered fully before using mains water. As such, the contractor should optimise use of surface water as much as is practical, as well as investigating whether any of the site’s SUDS are suitable for dust suppression water, before resorting to mains. Once this has been achieved, the contractor can then consider what technologies are available to reduce the mains water requirement for dust suppression. The following actions are recommended:

Utilise hydraulic spinning systems as opposed to traditional splash plate system - these systems use a hydraulic

motor to create a fine mist. Due to this efficient mist pattern, the same (or greater) performance can be achieved

with significantly less water.

Utilise fan misting systems as opposed to traditional rain gun systems - again, a fine mist is created and sprayed

over the required area. Due to this efficient mist pattern, the same (or greater) performance can be achieved with

significantly less water.

As well as reducing water consumption, these systems have the added bonus of reduced filling time (due to the reduced

water consumption). The contractor could also consider the use of dust suppressant additives to complement these systems. These additives act to reduce the surface tension of water, which effectively increases the time taken for the water to dry out. Note - it is possible that surface or SUDS water could not be used in the misting systems detailed above, due to the reduced water quality. As such, once such systems were purchased/hired, they may only be usable with mains water. Estimated Savings There is currently very little information known regarding the current mains water requirement for dust suppression, and as such it is difficult to estimate savings. The following assumptions have been used in this instance:

Current splash plate and rain gun systems have ~ 1,150 lpm capacity

Hydraulic spinning systems have ~ 100 lpm capacity

Fan misting systems have ~ 35 lpm capacity

4 hours per week of mains-water splash plate system operation converted to hydraulic spinning system (based on

operation at full capacity)

1 hour per week of mains-water rain gun system operation converted to fan misting system (based on operation at full capacity)

Thus, weekly savings of around 318.9 m3 could be achieved. However, additional investigation is required to confirm the current magnitude of mains water used for dust suppression vehicles, in order to refine the estimation of potential savings.

Monitoring & Targeting The contractor’s current management of water consumption across the site could be improved, and the implementation of a structured Monitoring & Targeting (M&T) system is recommended. In the first instance, it is key that the site’s water consumption is more accurately recorded. This will involve taking regular meter readings for areas where meters are installed, and by installing meters where they are not. The following 2 actions are recommended (as a minimum):

Track water consumed (m3) per week, and assess for erroneous consumption.

Once per month, conduct brief out-of-hours assessment of baseload water consumption.

These actions should help identify (and eliminate) unnecessary water consumption on site. Where possible, KPIs should be created for each area. For the offices, this would likely be ‘m3 consumed per office-based staff member’ or similar. For the batching plant, raw material input or product output could be used.

Estimated Savings

Estimating the savings from such an action is difficult, and varies from site to site. Based on a 5% reduction in site water

consumption, savings of around 3.4 m3/week could be available. As not all areas have been quantified, actual savings

could be higher.

86

Appendix 7 Site 7: Education (High School) Site

Introduction

Site 7, located in England, was audited on Wednesday 23 March 2011. The following information applies to the project:

Value of Site (contractors output) £23,000,000

Footprint Area of Site (m2) 19,295

Typical Site Working Hours

Monday - Friday: 08:00 - 18:00

Saturday: 08:00 - 13:00 (only sometimes)

Sunday: N/A

Maximum Number of People on Site ~120

Phase of Construction Piling is currently the primary site activity.

Classification Education

Project Use Class High School

Project Type Demolition and New build

Construction Type Not recorded

Client Type PFI

Contractual Agreement Joint Venture

The contractor commenced the project at the end of May 2010. It is intended that the main build (which incorporates demolition of existing buildings, and construction of replacement buildings) will be complete by November 2012. Following this, the remaining works (which will include external hard landscaping and sports pitches) will take place until October 2013. The school is still open to students, and the contractor’s work is currently restricted to an area of 7,575 m2 within the site’s 19,295 m2 envelope. There were 8 employees from the contractor’s company, 10 ground-workers and 6 pilers on site on the day of the audit (i.e. 24 in total). The maximum shown above (i.e. 120) will be reached at a later stage of the project, where site activity may increase.

Water Supply

The contractor is utilising the school’s existing mains water supply, and have taken branches from this distribution

network at 2 points. Each of these distribution networks has been fitted with a sub-meter (SP1 Meter and SP2 Meter),

and the contractor is billed by the school for the water they use on a volumetric basis. Although it is eventually intended

that SP1 will provide all domestic/welfare water, and SP2 will provide all site water, most of the site water currently

comes via SP1. The only water which has been used via the SP2 meter (45 m3 at the time of the audit) was for dust

suppression during the demolition a particular Building.

A basic site Water Plan is available, which shows:

Location of site offices, and domestic/welfare facilities (and corresponding water usage points)

Two connections to the school’s mains water supply

Sub-meter locations

Two external water usage points for site water

87

Site Water Consumption SP1 Meter

With the exception of the 45 m3 used for dust suppression during the demolition a particular building, all site water

consumption has been used via the SP1 Meter. Since regular meter readings commenced on 11 January 2011, the

following chart shows the Specific Water Consumption (SWC) of this meter has varied:

The average SWC (since 11 January 2011) is 20.9 m3/week. Assuming a project duration of 1,233 days (i.e. 176.1

weeks), which corresponds to 31 May 2010 until mid-October 2012, the total water consumption via SP1 Meter may be

in the region of 3,688.8 m3 at project end.

SP2 Meter

The installation date of SP2 meter is currently unknown, but has been estimated at the beginning of December 2010,

giving a SWC of around 2.9 m3/week. Assuming a project duration of 1,233 days (i.e. 176.1 weeks), the total water

consumption via SP2 Meter may be in the region of 506.2 m3 at project end.

Combined

Based on the values noted above, the total water consumption of the project is estimated at around 4,195 m3. Using the

value of the site as noted above, the Current Price Strategic Forum Key Performance Indicator (KPI) for the project

would be around:

182.0 m3/£million contractors output

88

Water Consuming Areas/Applications

The following table summarises the main water using areas/applications on site:

Area/Application Comment

SP1 Meter

This meter currently feeds all site water use.

SP2 Meter [NO PHOTOGRAPH]

This meter was used to provide dust suppression water for the demolition of a single building. It has not been used since this demolition was complete.

Domestic and welfare facilities

The site contains the following water using areas/applications:

Toilets (urinals were waterless)

Canteen (self-catering)

Shower (rarely used)

Agitator

The following hose is used to clean the agitator, and for providing make-up water into the concrete mix (as and when required):

The agitator is fed by concrete wagons which arrive from a local concrete batching plant. It is estimated that 9 – 10 concrete wagons arrive on site each day, though this number is expected to increase as the project progresses. The agitator has a 1 m3 storage tank attached to its rear, which supplies the hose pictured to the left. The contractor reports this tank is filled (on average) every second day. Based on a daily consumption of 500 litres, and a 5.25 day

working week, the agitator may consume around 2.63 m3/week. The contractor reports that the lengthy time it takes to fill the water tank help to promote a water efficient culture.

89

Area/Application Comment

High Pressure Washer

The following double-nozzle system is used with the system:

The High Pressure Washer has a 1 m3 storage tank associated with it. The contractor reports this is filled (on average) once every 3 days. Based on a daily consumption of 333.3 litres, and a 5.25 day working week, the system may consume around 1.75 m3/week. The High Pressure Washer is used to clean the following:

Concrete pump associated with agitator

Inside and outside the agitator vessel

Concrete delivery lines (i.e. concrete lines leading

from agitator to piling machine). The contractor reports that the lengthy time it takes to fill the water tank help to promote a water efficient culture.

No other current water consuming areas/activities were reported by the contractor, or noted during the site audit. The following were reportedly undertaken previously, or will be undertaken at a future stage of the project:

Dust suppression during building demolition

Dry-mortar silo(s)

Wet trades It was decided to monitor the volumetric flow through SP1 Meter for a sustained period to better understand how the demand of the site may typically vary:

90

The tanks associated with the Agitator and High Pressure Washer are filled at the start of the day (when required) and so the water profile shown above should relate only to domestic and welfare water consumption. The profile appears fairly typical of water used for these purposes. Over the duration of the monitoring period (i.e. 13:11 - 15:57) around 0.541 m3 of water was used, giving an average demand of 0.20 m3/h. Based on a 52.5 hour working week, water consumption associated with domestic and welfare facilities may account for around 10.5 m3/week.

Water Mass Balance (SP1 Meter) Based on the information available at present, the following provisional water mass balance for SP1 Meter has been prepared:

Activity Water Use (m3/week)

Agitator Water Supply 2.63

High Pressure Washer 1.75

Domestic and Welfare Facilities 10.5

Unaccounted 6.02

Total 20.9

The ‘Unaccounted’ water use noted above is simply the total water use minus the known activities.

Areas of Opportunity The following table summarises the areas of opportunity for water efficiency actions on site:

Action Water Savings

(m3/week)

Domestic and Welfare - Efficiency Improvements 2.6

Agitator -Trigger Operated Spray Gun Control 0.13

Wastewater Recycling 0.26

Monitoring & Targeting 0.21

TOTAL 3.2

By implementing all the actions, site water consumption could be reduced by around 15.3%. Further details on each of

these actions are outlined below.

Domestic and Welfare - Efficiency Improvements

Wash Hand Basins/Sinks

All the Wash Hand Basins (WHBs) and sinks on site are directly fed from mains (cold taps only), are operated using

twist/turn or percussion (i.e. push) mechanisms and have simple flow patterns (i.e. no spray-head attachment). There

are a number of efficiency problems with these types of systems, including:

Flow from taps will vary directly with mains pressure, and will generally be too high (< 5 litres per minute is good

practice).

Potential for taps to be left running for extended period (i.e. no auto-isolation of flow) for taps without percussion mechanism.

Due to basic flow pattern (i.e. no spraying) more water is required for effective cleaning.

In the first instance, the flow rates from a number of cold taps were monitored to provide a greater understanding of the

potential for water savings - the following table summarises the findings:

Area Application Cold - Volume

Flow (lpm)

Good

Flow

(lpm)

Fair

Flow

(lpm)

Poor

Flow

(lpm)

Comment

Canteen Sink 16.6

<5 5 - 10 >10 Poor performance in all instances.

Toilet WHB (1 of 6) 12

Toilet WHB (2 of 6) 12

As such, it can be seen that every outlet is performing poorly with respect to water efficiency.

91

Also, it was noted that the percussion mechanisms in some areas have excessive operating times. For example, the toilet

WHBs which were assessed had operating times of 25 - 27 seconds, far in excess of what is required.

The following improvements are recommended:

Percussion mechanisms fitted to cold taps which do not currently have.

Adjust (or replace) percussion mechanisms with excessive operating times.

Install Pressure Reduction Valve (PRVs) to reduce operating pressure to cold taps.

This will ensure a maximum distribution pressure and/or operating time, thus minimising wastage.

Note - if the contractor is convinced that most activities in the Canteen will use the same volume of water independent

of flow (e.g. filling a kettle), then installation of water efficiency devices is not recommended.

Toilet Cisterns

The toilet cisterns appeared to be standard volume, single-lever flush type. Generally speaking, Cistern Volume Adjusters

(CVAs) can be installed inside such cisterns to reduce effective flushing volumes (by displacing a portion of the water

inside) without adversely affecting performance. Following discussions with the cistern manufacturer(s) to confirm, CVAs

should be trialled in a number of cisterns. Assuming no operational problems ensue, all toilet cisterns on site should have

them fitted.

Although larger (i.e. ~3 litres) CVAs are available, 1 litre ‘Save-A-Flush’ systems are recommended in this instance. More

information can be found at http://www.dry-planet.com/products.html.

Estimated Savings

Based on a 25% reduction in the water consumption for domestic and welfare purposes, weekly savings of around 2.6

m3 could be achieved.

Agitator - Trigger Operated Spray Gun Control

The hose associated with the Agitator was controlled using a quarter-turn isolation valve. Although this was not

observed to be leading to any inefficiencies, general good practice suggests this should be avoided due to the risk of the

hose being left on when not in use. As such, it is suggested that the contractor install trigger operated spray gun control

on the hose.

Estimated Savings

Based on a 5% reduction in the water consumption of the Agitator, weekly savings of around 0.13 m3 could be achieved.

Wastewater Recycling

At present, the wastewaters from the Agitator and the High Pressure Washer are discharged without any attempt at

recycling. It may be possible to implement a rudimentary collection system to collect a portion of the wastewater, which

could then be used as the make-up water in the Agitator. The contractor would have to ensure this did not have any

detrimental effect on the quality of the concrete.

Estimated Savings

The portion of the Agitator which is currently used for make-up water is currently unknown, and so the potential savings

from this action can’t be accurately estimated at this time. Assuming 10% savings can be made, weekly savings of

around 0.26 m3 could be achieved.

92

Monitoring & Targeting

Once the proposed changes to the water distribution system have been implemented (i.e. one meter feeds domestic and

welfare facilities only), then it is recommended that the contractor improve their current monitoring system to improve

awareness of site water consumption. Actions to consider are:

There is currently some variation in the timescales between meter reads - ensure regular weekly reads are taken,

and with this consistency the numbers obtained will begin to take on more meaning (e.g. high or low figures are

more likely to be noted).

Consider creation of KPIs, to relate water consumption to a particular measure of site activity (e.g. average staff

numbers over the monitoring period). This will improve the contractor’s chances of noting (and eliminating)

erroneous water consumption.

On a regular basis (e.g. monthly), conduct a brief out-of-hours baseload assessment to ensure site water

consumption drops to zero when there is not activity.

Estimated Savings

Estimating the savings from such an action is difficult, and varies from site to site. Based on a 1% reduction in site water

consumption, savings of around 0.21 m3/week could be available.

93

Appendix 8 Site 8: University (Laboratory) Building Introduction

Site 8, located in Scotland, was audited on Wednesday 23 March 2011. The following information applies to the project:

Value of Site (contractors output) £10,000,000

Footprint Area of Site (m2) 3,500

Typical Site Working Hours

Monday - Friday: 08:00 - 18:00 (generally, most people left by 17:00)

Saturday: 09:00 - 16:00 (as required)

Sunday: N/A

Maximum Number of People on Site ~ 70 (current)

Phase of Construction Main external envelope nearing completion. Finishing trades internally on-going.

Classification Education

Project Use Class University/College

Project Type New Build & Refurbishment

Construction Type Steel Frame

Client Type University

Contractual Agreement Individual Agreement

There are currently around 70 persons undertaking work at the Site. The project is the addition of an extension to an

existing University building (including refurbishment of the existing building).

The project started in July 2010 is expected for completion in September 2011.

Water Supply There is one Business Stream meter which serves the construction site and the existing water supply within the original

building. A detailed water schematic for the site does not currently exist, however, the site contact provided a hand drawn

schematic. As well as the water supply to the Site Cabin/Welfare Compound (which contains the domestic and welfare facilities), a branch feeds off to the North-side of the Site to supply the water for the mortar silos.

94

Site Water Consumption

The water supply to the Site was monitored using a clamp-on ultrasonic flow-meter (shown above).

The following chart shows the results of the profiling exercise, which took place between 12:27 - 17:24:

The average consumption during this time was 0.26 m3/h of which 0.04 m3/h appeared to be a baseload use, therefore,

an occupied usage of 0.22 m3/h excluding baseload. Based on a 57-hour working week, the weekly consumption may be

around 12.54 m3/week excluding a baseload of 6.72 m³/week (or total weekly use of 19.26 m3/week). Assuming the

project commenced on 01 July 2010 and is forecasted to end on 30 September 2011, and that the weekly water

consumption noted above is the average water consumption at the end of the project, the total water consumption of

the project may be around 1,238.14 m3. Based on the value of the site as noted above, the Current Price Strategic

Forum Key Performance Indicator (KPI) for the project would be around:

123.7 m3/£million contractors output

The site has been tracking water use on a monthly basis and current total consumption is already at 863 m³ as of 01

March 2011. The below graph shows the monthly usage.

Site Water Consumption

0

100

200

300

400

500

600

700

800

900

1000

Jul-10

Aug-1

0

Sep-1

0

Oct-

10

Nov-1

0

Dec-1

0

Jan-1

1

Feb-1

1

Mar-

11

Us

ag

e m

3

Total Usage

Monthly Usage

95

The site encountered several water pipe ruptures in December 2010 and January 2011 due to the extreme cold weather

which has resulted in the increased water use during these months. Therefore, by considering the current water use

data to date, and the estimated water use per week (based on the monitoring data above), it is calculated that the

actual water use may be more in the region of ~1,440 m³. Based on the value of the site as noted above, the Current

Price Strategic Forum Key Performance Indicator (KPI) for the project would be around:

144.0 m3/£million contractors output

Water Consuming Areas/Applications

The following table summarises the main water using areas/applications on site:

Area/Application Comment

Business Stream Water Meter

Water meter located in the centre of the construction site in a small cabin. This cabin also contained a small pumping station for the university and contained a single sink.

Domestic and Welfare Facilities

The domestic and welfare facilities are located to the south of the construction site, and incorporate:

Shower Block (Cabin) Gents Toilet (Cabin) Canteen (cabin) Main Project Office Block (Series of Cabins) The individual areas are fed by a combination of flexible plastic and copper pipework.

Mortar Silos

There is a single mortar silo next to the welfare cabin on site

(pictured left). As well as the water feed to the silo, this area has an individual water draw-off point. The mortar silos are CPI Euro-mix - further information on the units can be found at: http://www.euromix.com/

Testing of Building Services [NO PHOTOGRAPH]

The site was scheduled to test building services during the day of the audit.

No other current water consuming areas/activities were reported by the contractor, or noted during the site audit.

96

Water Mass Balance Based on the information available at present, the following provisional water mass balance for the site has been prepared:

Activity Water Use (m3/week)

Domestic and Welfare Facilities 10.5

Mortar Silo 2.04

Leak on feed to Mortar Silo 6.72

Total 19.26

This is based on the water consumption of the site on the day of the audit and includes a baseload of 6.72 m3/week. The domestic and welfare water consumption has been estimated based on 70 people consuming 25 litres per day (for facilities without a food-preparation canteen), over a 6-day (57 hour) working week. While there was a food-preparation canteen the water use was negligible. The water use of mortar silos has been estimated based on the total consumption (19.26 m3/week) minus the know consumptions (i.e. 10.5 + 6.72 m3/week). To improve the accuracy of the water mass balance for the site, sub-metering of each area is recommended.

It was identified during the site visit that the water using activities involved in the testing of building services were supplied using water from another source so this monitoring data was not captured. These testing activities were not undertaken during the site visit.

Areas of Opportunity

The following table summarises the areas of opportunity water efficiency actions for the site:

Action Water Savings

(m3/week)

Domestic & Welfare Facilities – Efficiency Improvements 0.74

Repair Leak on feed to Mortar Silo 6.72

Monitoring & Targeting 0.19

Total 7.65

As such, it is estimated that the contractor could reduce site water consumption by around 39.7%.

Further details on these actions are outlined below.

97

Domestic & Welfare Facilities - Efficiency Improvements

This site had the most water efficient set-up for domestic and welfare facilities that have been visited during this initial

audit programme. The following practices were identified:

Water Supply: Pressure reducing valves were installed in each level of the welfare cabin to control mains water supply

pressure (see below) which is good practice.

Wash Hand Basins: Spray inserts were installed in each of the site taps.

There is the potential for taps to be left running for extended period (i.e. no auto-isolation of flow). Therefore, consider,

replacing the existing taps with percussion-controlled equivalent.

Urinal Flush Control: The site had implemented a hydraulic valve to minimise urinal flushing. This is a good practice.

The toilet cisterns appeared standard size (i.e. ~ 6 - 8 litres), with a single lever flush mechanism, and did not appear to

have any water efficiency devices incorporated:

In the first instance, the cistern volumes should be confirmed. Where a cistern volume is 6 litres or less, retro-fitting of

water efficiency devices is not recommended. However, where the cistern volume is 7 litres or more, consideration

should be given to the installation of Cistern Volume Adjusters (CVAs). CVAs can sometimes be installed inside toilet

cisterns to reduce effective flushing volumes (by displacing a portion of the water inside) without adversely affecting

performance. Following discussions with the cistern manufacturer(s) to confirm suitability, CVAs should be installed in

any cisterns with capacities equal to or above 7 litres.

98

Although larger (i.e. ~3 litres) CVAs are available, 1 litre ‘Save-A-Flush’ systems are recommended in this instance. More

information can be found at http://www.dry-planet.com/products.html.

Estimated Savings

Assuming 70% of the water consumption of the domestic and welfare facilities is associated with WHBs/sinks and toilet

flushing, and that 10% savings can be achieved, weekly savings of around 0.74 m3/week could be achieved.

Repair Leak on Feed to Mortar Silos

As a consequence of regularly moving location, flexible water pipework on construction sites can be prone to minor

damage resulting in leaks (as per the following pipe associated with the mortar silo):

The contractor should ensure all water pipework is maintained regularly, and any leaks (such as that pictured above) are

repaired once observed.

Estimated Savings

Repairing the leak on the mortar silo may achieve water savings of around 6.72 m3/week.

Monitoring & Targeting

It is recommended that the contractor implements a few improvements to the existing Monitoring & Targeting (M&T)

system for the site’s water consumption - this will involve undertaking two main actions on a regular basis:

Increase tracking of water consumed to m3 per week, and assess for erroneous consumption (this may have

identified the leaks in December 2010 and January 2011 sooner).

Once per month, conduct brief out-of-hours assessment of baseload water consumption.

These actions should help identify (and eliminate) unnecessary water consumption on site.

Estimated Savings

There is not currently enough information to estimate the savings associated with these actions, and as such an arbitrary

figure of 1% of the current site water consumption will be used - this accounts to 0.19 m3/week.

99

Appendix 9 Site 9: Leisure (Theatre) Venue

Introduction Site 9, located in Scotland, was audited on Tuesday 29 March 2011. The following information applies to the project:

Value of Site (contractors output) Undisclosed

Footprint Area (m2) 25,500

Typical Site Working Hours

Monday - Friday: 08:00 - 18:00

Saturday: Do not currently work, but expected to start eventually

Sunday: May be worked nearer end of project

Maximum Number of People on Site ~ 80

Phase of Construction

Preparatory work, such as:

Perimeter drainage Piling Concrete base for towers Reinforcement

Classification Leisure

Project Use Class Theatre

Project Type New build.

Construction Type Concrete frame and steel frame

Client Type Local government

Contractual Agreement Individual company

The project is in its early stages. Although there was a site presence in early 2011 (for cabin installation, etc.),

construction only officially commenced on 14 February 2011. It is expected that the project will run until December 2012. The maximum number of people on site applies only to the project to date - numbers are expected to increase to

500/600 at later stages.

Water Supply

The project relates to a new build entertainment theatre on an existing (and still operational) entertainment site. As such, the contractor has accessed the site’s existing water supply. At present, the water distribution network for the

construction site is basic - one branch of the network feeds the canteen, and there is another branch to a single stand-

pipe. As well as providing the water for any construction-based water activity, this stand-pipe is used to fill an 1 m3 Intermediate Bulk Container (IBC) which in turn provides water for the temporary toilet block. In the coming weeks, the

temporary toilets will be de-commissioned and permanent toilets (with a direct mains connection) will be implemented.

The contractor does not pay the client for use of their water supply, and thus there is no financial incentive for water

efficiency improvements - this may act as a barrier to improvement.

Site Water Consumption

A meter reading was taken at the end of February 2011 - the site had used 11.4 m3 at this time. A subsequent meter reading was taken on the day of the audit (i.e. 29 March 2011), and 73.245 m3 has been used (at 09:38). As such,

around 61.845 m3 of water was used in this 29 day (i.e. 4.14 week) period. The Specific Water Consumption (SWC) of

the site during this period was therefore around 14.9 m3/week.

Assuming the SWC remains the same until project completion, and assuming a project completion date of 15 December

2012, the site may consume another 1,337m3 of water. This would result in a total water consumption of 1,410 m3 over the duration of the project.

100

Water Consuming Areas/Applications The following table summarises the main water using areas/applications on site:

Area/Application Comment

Water Meter

The main water meter, located at the site boundary.

Canteen

There is a self-catering canteen on site, which includes 2 sinks. Between 09:38 - 16:02 the site consumed 0.4 m3 of water - this corresponds to an average demand of 0.0625 m3/h. This water is associated with the Canteen, as well as the leak from the stand-pipe. Assuming the leak accounted for 25% of this consumption, the Canteen utilised an average of 0.0469 m3/h. Based on a 50-hour working week, the Canteen may use around 2.345

m3 of water.

IBC

The 1 m3 IBC which provides water for the temporary toilets. It is filled using a flexible hose connected to the stand-pipe. The contractor reports that the tank is filled once per day, and typically it may be 25% full when it is re-filled. As such,

the temporary toilets may use around 0.75 m3 per day (3.75 m3/week).

101

Area/Application Comment

Toilets

Toilets containing:

3 x WHBs

3 x WCs

3 x urinals (with 1 communal cistern)

Stand-pipe

There is a single stand-pipe providing all site water use (except for Canteen). There is a leak associated with the stand-pipe, which increases in magnitude when the isolation valve is opened. It has been estimated that the leaking stand-pipe wastes around 0.0156 m3/h of water when the valve is shut (valve generally open for around 45 minutes each day, in order to fill IBC). Assuming that the volumetric flow rate of the leak when the valve is open is around 5 times that of when it is shut, it would account for around 0.0781 m3/h. Thus, based on these values, the leak accounts for around 2.855 m3 each week.

No other current water consuming areas/activities were reported by the contractor, or noted during the site audit. The following were reportedly undertaken previously, or will be undertaken at a future stage of the project:

Plant commissioning

Piling

Wet trades

Mortar Silo (possibly)

Water Mass Balance Based on the information available at present, the following provisional water mass balance for the site has been prepared:

Activity Water Use (m3/week)

Canteen 2.345

Temporary Toilets 3.750

Stand-pipe Leak 2.855

Unaccounted 5.95

Total 14.9

The ‘Unaccounted’ water use noted above is simply the total water use minus the known activities. In order to improve the accuracy of the water mass balance, the contractor may wish to install sub-meter on the domestic and welfare facilities (once temporary toilets removed and permanent toilets in place).

102

Areas of Opportunity The following table summarises the areas of opportunity for water efficiency actions on site:

Action Water Savings

(m3/week)

Wash Hand Basins/Sinks - Efficiency Improvements 0.46

Repair Leaking Stand-pipe 2.855

TOTAL 3.315

By implementing all the actions, site water consumption could be reduced by around 22.2%. Further details on each of

these actions are outlined below.

Wash Hand Basins/Sinks - Efficiency Improvements

All the Wash Hand Basins (WHBs) and sinks on site are directly fed from mains (cold taps only), are operated using

twist/turn mechanisms and have simple flow patterns (i.e. no spray-head attachment). There are a number of efficiency

problems with these types of systems, including:

Flow from taps will vary directly with mains pressure, and will generally be too high (< 5 litres per minute is good practice).

Potential for taps to be left running for extended period (i.e. no auto-isolation of flow).

Due to basic flow pattern (i.e. no spraying) more water is required for effective cleaning.

In the first instance, the flow rates from a number of cold taps were monitored to provide a greater understanding of the

potential for water savings - the following table summarises the findings:

Area Application

Cold -

Volume

Flow (lpm)

Good

Flow

(lpm)

Fair Flow

(lpm)

Poor Flow

(lpm) Comment

Canteen Sink (1 of 2) 10.5 <5 5 - 10 >10

Poor performance in

both areas. Temporary Toilets WHB (1 of 3) 10.2

As such, it can be seen that both outlets are performing poorly with respect to water efficiency.

Assuming the new toilets (yet to be commissioned) are similar to the Temporary Toilets, the following improvement

actions are recommended:

The following improvements are recommended:

Percussion mechanisms fitted to cold taps which do not currently have them.

Install Pressure Reduction Valve (PRVs) to reduce operating pressure to cold taps.

This will ensure a maximum distribution pressure and/or operating time, thus minimising wastage.

Note - if the contractor is convinced that most activities in the Canteen will use the same volume of water independent

of flow (e.g. filling a kettle), then installation of water efficiency devices will have less affect.

Estimated Savings

Assuming the sinks/WHBs account for 30% of the water consumption of the Canteen and the Temporary Toilets, and

that a 25% reduction in this value can be achieved, weekly savings of around 0.46 m3/week could be achieved.

103

Repair Leaking Stand-pipe

It is recommended that the leaking stand-pipe is repaired, to provide weekly savings of around 2.855 m3.

Note - since site audit was undertaken the contractor has repaired this leak (as per photograph below), and regularly

checks the condition of the connection:

104

Appendix 10 Water Audit Methodology This methodology has been prepared to allow contractors to self-audit construction site. Following these steps will allow robust data collection on water consumption across a variety of site processes, which will subsequently allow areas of high water consumption and water wastage to be identified for improvement. A series of supporting checklists and data collection pro-forma accompany this methodology and are referred to below. Water Audit Procedure Flowchart The figure below summarises the process of carrying out a water audit.

Define purpose

Identify site

Contact site staff

Check preparation with

Form A

Identify required

monitoring

Install monitoring

Record monitoring information

(use Form B)

Ensure site diary completed

Report

Gather background information

Prepare site diary

Carry out walk

through survey

Collect data on water use for

duration of audit

(use Form C)

105

Preparation

Thorough preparation for a water audit ensures maximum results and efficiency. During the preparation phase, Form A

should be completed as a record that correct preparation has been carried out.

1. Define purpose of water audit, for example:

a. To determine the overall water use of the construction site. b. To determine the water use of a particular process or technology. c. To determine the water savings associated with implementation of a particular behaviour change. d. To determine the impact of using efficient product 'X' instead of standard product 'Y', or e. To determine the volume of water used by site accommodation on the construction site.

2. Identify site for water audit:

a. Consider the type of site, i.e. new domestic, new infrastructure (specify as road, rail, flood defence or structure, such as bridge for example), new retail, new office, new education, new health, new other non-domestic or refurbishment and maintenance. This is particularly important if the water audit is to compliment prior audits.

b. Consider the phase of construction in which the audit is due to take place and any time limitations if the audit is intended for a particular construction phase. This is particularly important if the purpose of the water audit is to determine the water use of a particular process or technology during a certain construction phase.

3. Gather background information, including:

a. Site plan to include location of abstraction points, stand pipes, connection to mains, water draw-off points and site accommodation.

b. Operating schedule of site, including number of employees per shift. c. Copies of proposed billing rates for water for the expected construction period, e.g. metered rate for mains

water connections, fixed charges for stand pipes, any abstraction chargers and charges for tankered water. d. Water using equipment on site list and manufacturer's recommended flow requirements.

4. Ensure contact details for site staff are available, including, but not limited to:

a. Site Manager.

b. Environment Manager (if appropriate).

5. Prepare site diary:

a. Maintain a site diary to record specific water using processes on site during the audit period. Particular attention should be paid to changes in water use practices during construction.

b. Identify appropriate site staff to ensure the site diary accurately reflects what is happening on the site.

Water Use Data

Quantitative information relating to the volume of water used is key to a successful and useful audit process. During the

definition and installation of the monitoring equipment, Form B should be completed to record how water use data is

monitored.

1. Based on the purpose of the water audit, define the required monitoring points for the construction site. These

might include: a. Each abstraction point, stand pipe and connection to mains. b. Critical sections of the site. c. A point for parts of the site at different phases of work. d. Points prior to specific draw-off points for a particular purpose, e.g. site accommodation or cement batching, or e. Points downstream of specific draw-off points if these exist so that consumption for a specific purpose can be

calculated.

2. Decide on the appropriate monitoring equipment to install, this could be:

a. A water meter of appropriate size for the location (to be manually read at a set frequency). b. A water meter of appropriate size for the location with logging equipment (to be manually downloaded at a

set frequency), or c. A water meter of appropriate size for the location with logging equipment and telemetry to allow remote

download of information.

3. Install monitoring equipment. Take initial meter readings.

106

Conducting the Audit

If the purpose of the water audit is to determine the impact of using a certain process/technology or implementing a

particular behaviour change, the water audit should monitor water use before and after the change in practice. This will

allow the impact of the change in practice to be most accurately defined as most other external factors will remain the

same. The site diary should be used to identify any external factors that will affect the results.

1. Conduct a walk-through survey of the site:

a. Identify and record water use on the construction site. b. Ensure correct monitoring of water use is in place. c. Where applicable, witness use of specific water using equipment or processes and record actual water use or

behavioural notes. d. Make a photographic record of water use on site. In particular photos need to be taken of good or poor

practice in terms of water efficiency.

2. Collect data on water use from the monitoring system.

3. Form C should be used to record audit information and the data collected at a suitable frequency and duration:

a. The appropriate time scale and frequency of meter reads will depend on site type, timetable and monitoring equipment installed. It is suggested that as a minimum monthly readings should be taken.

b. The duration of the water audit will depend on the purpose of the audit (i.e. for the duration of construction, the duration of a construction phase(s) or the duration that a particular technology or process is used).

c. To analysis and compare water audit results it is vital to capture information which can form data sets for normalisation. The primary data set for this will be hours worked, this can usually be obtained from site safety records.

Analysis of Audit Information

1. Report the results of the water audit using Form B, Form C (with Form D) and the information gathered for Form A.

2. Prepare an audit report either upon completion of site work or on an annual basis. If appropriate a preliminary

report can be prepared and circulated to staff to highlight water use and identify potential benefits.

107

Form A: Preparation Checklist

The purpose of this checklist is to ensure that all relevant and necessary information is gathered for the water audit.

Preparation

Purpose of water audit defined.

Site identified to carry out water audit.

Site type and phase of construction considered.

Contact details for appropriate site staff.

Site plan, to include location of abstraction points, stand pipes, connection to mains, water draw

off points and site accommodation.

Operating schedule of site, including number of employees per shift.

Proposed billing rates for water for the expected construction period, e.g. metered rate for

mains water connections, fixed charges for stand pipes, any abstraction chargers and charges

for tankered water.

List of water using equipment on site and manufacturer's recommended flow requirements.

Water Use Data

List of meters installed on site.

Records of tankers brought to site.

List of water using equipment for flow rate records.

Site Water Use Diary

Site diary prepared and assigned to appropriate person.

Water Saving Equipment and Practices

List of water saving features and behaviours being implemented.

Cost of water saving feature and cost of 'standard' feature identified (where applicable).

108

Form B: Site Processes by Meter

This form should be completed based upon the site plan and discussion with site staff as appropriate.

The following schematic indicates where uses should be assigned. For example, draw-off points one, two and three

would be assigned to Meter One. Draw-off point four is assigned to Meter Two.

Meter Ref. Description of

Location

Water Uses, Equipment

and Processes

'Downstream' of Meter

Other Information

Downstream Meter

Y/N and Ref. if

applicable

Draw-Off Point

Three

Draw-Off Point

One

Draw-Off Point

Two

Draw-Off Point

Four

Meter

One

Meter

Two

109

Form C: Data Collection

Date of audit start: Date of audit end:

Audited by:

Site name:

Location (Region):

Purposed of audit:

Phase of construction at audit start:

Phase of construction at audit end:

Value of site (£million contractors output):

Footprint area of site: H

a

m²

Length of scheme, where appropriate (km):

Hours worked (by site staff):

Max number of people on site at any one time:

Classification: Civil Engineering Industrial Buildings

Commercial Offices Leisure

Commercial Retail Mixed Use Developments

Commercial Other Public Buildings

Education Residential

Healthcare

Project Use Class: please select using Table 1 in Form D

Project Type: Civil Engineering New Build

Demolition New Build and Refurbishment

Demolition and New Build Refurbishment

Fit Out Remediation

Construction Type: Civil Engineering Load Bearing Masonry

Composite Steel Frame

Concrete Frame Timber Frame

Light Gauge Steel

Client Type: please select using Table 2 in Form D

Contractual

Agreement: please select using Table 3 in Form D

Site diary completed:

110

Meter Ref

(see Form B) Reading

Date (and time)

Reading taken Comments

General Comments

111

Form D: Information for Form C

This form should be used to select the correct information to be entered on Form C.

Table 1: Project Use Class based on Classification

Civil

Engineering

Commercial

Offices

Commercial

Other

Commercial

Retail

Education Healthcare

Bridge Institutional Film/TV Studio Food Store Primary School/

Nursery

Hospital

Tunnel Suites Tele-

communications

Shop High School Nursing Home

Road Call Centre Newspaper HQ Retail Warehouse University/

College

Health Centre

Railway Other Postal Service Shopping Centre Student

Accommodation

Other

General

Infrastructure

Banks/Building

Society

Supermarket Sports Facilities

Earthworks Institutional Department

Store

Costal and River

Works

Retail - Other

Water Utilities

Gas Utilities

Electricity

Utilities

Sewage Utilities

Nuclear Utilities

Surface Carpark

Multi-Storey

Carpark

Filling Station/

Garage

Railway Station

Airport

Airport Runway

Transport Other

112

Table 1: Project Use Class based on Classification (Cont'd)

Industrial

Buildings

Leisure Mixed Use

Developments

Public Buildings Residential

Heavy Industry Cinema Houses/Shops Fire/Police Station Flats/Apartments

Light Industry Holiday Camp/

Village

Offices/Shops Government Houses

Food Industry Indoor Leisure Houses/Offices/

Shops

Embassies Care Home

Scientific Labs/

Research

Sports Hall/Centre Other Prison Service Hostel

Distribution/

Warehousing

Outdoor Sports/

Stadium

Residential Military

Accommodation

Chemical/

Pharmaceutical

Park/Playground Museums/Galleries Houses/Flats/

Apartments

Hi-Tech Manufacture Pub/Club Religious Centre

Farm Buildings Restaurant/Food Other

Other Theatre

Commercial

Exhibition

Mixed

Visitor Centre

Swimming Pool

Hotel

Other

113

Table 2: Client Types Table 3: Contractual Arrangement

Developer Alliance

Educational Trust Consortium

Foreign Government Individual Company

General Trust Joint Venture

Government Agency Strategic Partnership

Health Service Trust Other

Housing Association

Insurance Company

Investment/Finance Company

Local Government

Main Contractor

Manufacturing

PFI/DBFO Concessionaire

Private Individual

Retail Company

Single Project Developer

Single Project Trading Company

Trading Company

University

Utility Company

Other Specific Trusts

114

Matrix of Sites for Water Audits

The following table has been developed to identify the possible combinations of site type and construction phase which should be considered when conducting a water audit.

It is recommended that each combination of site type and construction phase should be subject to a minimum of three water audits to allow any trends to be identified. Due to the

expected variation in water use for each process across different sites, an increased sample size will result in significantly more robust results.

Site Type

New

Dom

est

ic

New

Infr

ast

ruct

ure

(Road)

New

Infr

ast

ruct

ure

(Rail)

New

Infr

ast

ruct

ure

(Flo

od D

efe

nce

s)

New

Infr

ast

ruct

ure

(Str

uct

ure

)

New

Reta

il

New

Off

ice

New

Educa

tion

New

Health

New

Oth

er

Non

Dom

est

ic

Refu

rbis

hm

ent

and

Main

tenance

Co

nstr

ucti

on

Ph

ase

Deconstruction

Off site manufacturing and assembly

Enabling works and remediation

Site accommodation

Corporate Offices

Construction on site

Fit-Out and Finishing

Landscaping

Commissioning

115

Appendix 11 Site 10: Commercial & Residential (Call Centre, Department Store, Apartments) Site Introduction Site 10, located in England, was audited between November 2011 - April 2012.

The average site water consumption is 321 m3/month, and it is estimated that savings of around 68.2 m3/month (i.e. a 21.3% reduction) could be achieved through undertaking a focused programme of water efficiency with respect to the welfare water consumption. The following information applies to the project:

Value of Site (contractors output) £150 million

Footprint Area (m2) See below

Typical Site Working Hours

Monday - Friday: 08:00 - 18:00

Saturday: 08:00 - 14:00

Sunday: No work

Maximum Number of People on Site See below

Phase of Construction See below

Classification Commercial & Residential

Project Use Class Call Centre, Department Store, Apartments

Project Type New Build

Construction Type See below

Client Type Investment/Finance Company

Contractual Agreement Individual Company

116

The project commented in May 2011, and is due to conclude in March 2013. It involves the construction of commercial and residential buildings via 3 distinct phases of work: Structure, Façade and Fit-Out. This is summarised in the table

below:

Building Specification Structure

Duration

Façade

Duration

Fit-Out

Duration

Commercial 1 (contains open-plan office and department store)

16 Storey & 10 Storey Steel Frame 49,000 m2 Gross Internal Area

(GIA) May 2011

to

March 2012

November 2011

to

November 2012

December 2011

to

March 2013

Residential

25 Storey (94 Apartments, Luxury) with 13,000 m2 GIA

9 Storey (74 Apartments, Affordable) with 9,350 m2 GIA

Concrete Frame

Commercial 2 (contains open-plan office)

7 Storey 3,675 m2 GIA Concrete Frame

At the time of audit completion, the Structure phase was complete (or nearing complete) for each building, and the

Façade and Fit-Out phases were in progress.

Water Consumption Summary

Since project commencement, around 3,335 m3 of water has been consumed (up to an inclusive of March 2012 consumption). The following chart summarises the site’s monthly water consumption.

The average Structure phase consumption, assessed during June - October 2012 inclusive (i.e. whole months where no

other work phases occurring), was 241 m3/month. The water within concrete used for slip forming and screeding during

the Structure phase is not accounted for in the above figures, as the concrete was brought to site ready mixed.

An overnight baseload check was undertaken which confirmed that there was no unauthorised water consumption.

Analysing water consumption alone does not provide any insight into water efficiency on site - it is generally expected

that water consumption throughout the different phases of a construction project will vary, sometimes significantly so,

as site operations will regularly change. As such, an increase in water consumption may not necessarily mean water

efficiency has reduced (or vice versa). By creating KPIs, which relate site water consumption to some measure of site

activity, it can help track water efficiency more accurately.

117

This will not always be a simple process for construction sites, due to the varying nature of site operations - there is not

always a practical and available KPI which applies. In this instance, KPIs for project turnover and average staff numbers

have been used:

Note: the financial KPIs above have not been adjusted for constant price, whereas the site KPI noted in Section 2 has been to allow comparison with the Constant Price Strategic Forum KPI. There is a significant variation in the KPI values returned, suggesting that on this occasion staff numbers and turnover alone may not be the best measure of expected water consumption. It is likely that the apparent spikes in water consumption are simply due to the operation of some significant water consuming activities, which do not necessarily involve increased staff numbers or turnover, and which are difficult to account for within a KPI.

Water Mass Balance

Through installation of a number of strategically placed water meters, the water consumption across the site was split in order to create a water mass balance of consumption. The results, compiled using data from a 2-week period in April 2012 during which 227 m3 was consumed, are shown below. It is noted that this is a “snap-shot” water mass balance during the stated period, and that it is likely to change (perhaps significantly) over the duration of the project. It can be seen that over the monitoring period the majority (around 85%) of site water consumption was related to the welfare blocks, with a relatively low amount of site-based water consumption. This is consistent with observations made during the site audit, where the level of site-based water consumption during the monitoring period generally appeared low.

M1

Commercial 1 (Office/

dpmt. store)

7.4% Commercial 2

(Office)

3.4%

Welfare

85.1%

Residential

4.1%

M3

M4

M2

Incoming Water Supply

KEY:

= Water Meter M

118

Water Efficiency Assessment Following an assessment of water use on site, it was found to be relatively water efficient with little opportunity for improvement. The following water consuming areas/activities were noted: Wet trades (e.g. block work, screeding, plastering, etc.); Slip forming; Welfare (toilets, food preparation canteen and offices); Manual cleaning activities; and Drinking water.

Slip forming, used to create the concrete frames for the buildings, appeared to be the largest site-based (i.e. non-welfare)

water consuming activity, and this activity ceased following completion of the structural phase of the works (i.e. March

2012).

In terms of the water used as an ingredient, this is strictly controlled for quality purposes and offers no opportunity for saving. The only variable water consumption used is to flush out concrete delivery chutes, to prevent hardening within.

Typically, this would be done entirely with water, with the water supply isolated once it “runs clear”. However, the site utilised a spherical projectile in the first instance, which not only significantly reduces the required flushing water, but also recovers valuable concrete product. This is good practice and is to be commended. In terms of welfare: Wash Hand Basins (WHBs) are likely to account for a significant portion of the welfare water consumption, and

represent an opportunity for improvement. The flow rate of WHBs fed directly from mains will vary with the mains pressure, and thus the site currently has little control over their water consumption. Consideration is being given to installing variable Pressure Reduction Valves (PRVs) at strategic locations around the distribution network to improve control. Two WHBs were monitored, and flow rates were found to be 9.8 litres/minute and 8.8 litres/minute - a good practice flow rate is < 5 litres/minute.

In general, percussion (push) taps were in use, which can be considered good practice. However, the operating times varied from WHB to WHB, and in some instances were excessive (i.e. > 10 seconds). The site is to undertake a review of each WHB to limit the operating time to a maximum of 5 seconds.

The large food preparation canteen, which serves food to several hundred staff each day, will consume large quantities of water. The site is to undertake a focused review of water using activities within the canteen.

Waterless urinals are in use and can’t be improved with respect to water efficiency. Water consumption within office areas (e.g. tea making) is not expected to account for a significant amount of

water.

The site also benefits from a well managed water metering/monitoring system. Since commencement of the project, monthly readings of each water meter used on site are undertaken, which provides an excellent platform from which to drive water efficiency. With the addition of 2 sub-meters as part of the audit, the site’s understanding of water consumption is well developed. Although the audit did not provide many opportunities for water efficiency improvements, it did provide an opportunity for creating some relatively robust benchmark data in relation to welfare water consumption - this is discussed further

below.

Benchmarking

As welfare appears to the largest water consuming activity on site, it is useful to consider the average welfare water consumption per staff member. Based on data from April 2012, when around 550 staff were working on site, the average daily welfare consumption was around 24 m3, which corresponds to a daily consumption of 44 litres per person per day. This is slightly above a typical value of 40 litres per person per day (for sites with a full food preparation canteen), and when considering that waterless urinals are in place it suggests there may be room for improvement.

Summary

The site is well managed with respect to water efficiency and the opportunity for site-based water efficiency improvements appears limited. However, the welfare-based water consumption is relatively high and is above typical levels, and may represent the greatest opportunity for water savings on site. Based on a 25% reduction in welfare water

consumption, which is challenging but should be achievable, potential savings of around 68.2 m3/month may be available - this corresponds to approximately 21.3% of total site water consumption. Based on low, medium and high unit costs for water and wastewater, as per the current UK charging schemes of the various water and wastewater operators, the following table summarises the potential financial benefits from achieving the water savings noted above:

119

Relative Cost of Water &

Wastewater

Combined Water & Wastewater Cost

(£/m3)

Monthly Water Savings

(m3/month)

Annual Water Savings (m3/year)

Annual Cost Savings (£/year)

LOW 1.53

68.2 818.4

1,252

MEDIUM 2.81 2,300

HIGH 5.27 4,313

It can be seen that location can have a significant impact on the financial benefits of water efficiency, in instances where water is charged on a volumetric basis.

120

Appendix 12 Site 11: Civil (Railway) Site Introduction Site 11, located in England, was audited between November 2011 - April 2012.

A number of different areas were identified for water efficiency improvements and, although they can’t be fully quantified at this time, are expected to offer a significant reduction in site water consumption. The following information applies to the project:

Value of Site (contractors output) £50 million

Footprint Area (m2) Unknown

Typical Site Working Hours

Monday - Friday: 08:00 - 18:00

Saturday: 08:00 - 13:00

Sunday: No work

Maximum Number of People on Site Typically, 220

Phase of Construction See below

Classification Civil Engineering

Project Use Class Railway

Project Type New Build & Refurbishment

Construction Type Civil Engineering

Client Type Local Government

Contractual Agreement Main Contractor

The project consists of the construction of a tunnel portal and railway station, as well as the demolition of an existing railway station and connection of the new railway station to the existing rail infrastructure. It is due to run from Mid-2011 until Early 2015. Associated works will include the construction of bridges, a six-span viaduct, retaining walls and a mechanical/electrical fit-out. It is difficult to define the project in terms of distinct phases, as typically there are a number of different activities occurring on site at any one time (e.g. excavation, hydro-demolition and piling taking place simultaneously).

Water Consumption Summary Managing water consumption at the site is a challenge, due to the use of a high number of unmetered standpipes as well as a faulty water meter, and quantification of the total site water consumption could not be undertaken. However, 4 metered standpipes were installed in preferred locations to allow quantification of a number of the higher priority water using areas, as well as a dedicated sub-meter on the wheel wash. The following table summarises the data which was captured during a period of around a month in March - April 2012:

121

Standpipe/ Sub-meter

Supply Size Monthly

Consumption Main Water Using Activities

Standpipe A1 2.5 “ 60 m3 Hydro-demolition, bentonite mixing, piling, road sweeper, high pressure washer.

Standpipe A2 2.5” 9 m3 Wheel wash (secondary supply), piling

Standpipe B1 1” Minimal Negligible throughout audit duration

Standpipe B2 1” Minimal Negligible throughout audit duration

TOTAL 118 m3

The wheel wash sub-meter consumption is higher than typical levels, as the monitoring period includes instances of

leaks/overflows. A typical consumption, if these had not occurred, is estimated at 24 m3/month.

Most major water consuming areas/activities are quantified in the table above. The most notable exception is site

welfare, which is likely to account for a significant percentage of the site’s water consumption. Also, the road sweeper

sometimes fills its tank off-site.

A weekend baseload check was undertaken which showed that there was no unwarranted water consumption through

any of the metered standpipes or the wheel wash sub-meter.

Water Efficiency Assessment The following table summarises the potential savings which have been identified following the water efficiency assessment which was undertaken:

Problem Solution Potential Savings

Inefficient Drive-on Wheel Wash Reduce pressure, repair ball float valve and regularly clean filter

10 m3/month (43% reduction)

Leakage Regular leak detection and repair Variable but significant

Operating high pressure washer at full capacity

Utilise existing flow control valve Dependent on application

Standard, inefficient vehicular dust suppression

Specify atomising/misting, efficient vehicular dust suppression

70% - 90% reduction

Welfare consumption with potential for improvement

Review of domestic and canteen facilities 32 m3/month (20% reduction)

Standard (i.e. non-recirculating) road sweeper

Specify recirculating road sweeper 19 m3/month (30% reduction)

Inefficient stockpile dust suppression Utilise fan misting systems Up to 90% reduction

122

Additional details on each opportunity, as well as activities/areas where no opportunity has been identified, are shown below.

Activity/Area Typical Water Consumption

Potential Savings

Comments/Actions

Drive-on Wheel Wash

Throttled Valve on Wheel Wash Supply

94 litres/wash 24 m3/month

40 litres/wash (43% reduction) 10 m3/month

The supply pressure was found to be excessive, and the water consumption per wash was reduced by 43% by throttling the valve on the water supply by around 50% (see photograph). The level of throttling may require alteration depending on site conditions (and thus savings may vary).

A faulty ball float valve was leading to a constant overflow of 900 litres/hour from the rear of the system, which corresponds to around 650 m3/month (if constantly active). Reducing the supply pressure and replacing the float valve eliminated this loss.

A blocked filter within the recirculation tank was leading to an overflow at the front of the system - regular cleaning of the filter unit has been implemented to prevent this re-occurring.

Including the elimination of these overflows, the actual reduction of the wheel wash water consumption is well in excess of the 43% (10 m3/month) stated.

The typical water consumption is likely to vary significantly depending on site conditions, weather, etc.

Leak Detection & Repair

Leak on 2.5” Standpipe

N/A Significant Several leaks were noted around the site, some of which were significant. In terms of the potential for water savings, improved leak detection and repair may be the action which provides the greatest opportunity.

The priority area for the site is the maintenance of standpipes and

associated fittings. On one occasion the below-ground connection point to the mains network on Standpipe A1 was loose, and on another occasion the hose connection to the same standpipe had a significant leak (see photograph), and on both occasions significant leaks were witnessed. Manually tightening the connection point, and installation of a jubilee clip, resolved these issues and led to significant water savings.

In order to reduce water losses from

leaks on site, regular leak detection is to be undertaken in conjunction with the existing health and safety walk-rounds.

123

Activity/Area Typical Water Consumption

Potential Savings

Comments/Actions

High pressure washing 13.2 litres/minute Monthly consumption dependent on highly variable operating times.

Savings are dependent on particular application

System used on site was a Brendon Powerwashers Bowserwasher Diesel, a system-type which is common on construction sites.

Maximum flow rate is 13.2 litres/minute, and the system allows users to control this flow through throttling a valve on the supply pipework.

In general terms, to achieve water savings, the user should reduce the flow rate to the minimum required for the particular application. The potential savings

will vary from application to application (and site to site) but could be significant in some instances.

In order to achieve these savings on site, users of high pressure washing systems on site are to be provided with training to ensure they operate the equipment as efficiently as possible.

Reducing the water consumption of the system will also reduce the frequency of top-up required - this could prove a greater benefit than the actual water savings in difficult

to access areas.

Vehicular Dust Suppression

Alternative to Splash Plate Vehicular Dust Suppression

Unknown (currently no mains water consumption)

70% - 90% System used on site utilises a 2,200 litre storage tank mounted on a small trailer which is driven around the site when dust suppression is required. The system utilises a traditional (and water inefficient) splash plate technique. As the system currently uses abstracted groundwater there is no opportunity for mains water savings.

Modification of the existing system to reduce water consumption is unlikely to prove practical, or even possible (as the unit is hired). As such, in order to improve the efficiency of vehicular dust suppression on site, consideration will be given to hiring water efficient alternatives to the current system at the next available opportunity. These alternative systems create a mist pattern (see photograph), which provides similar or even improved dust suppression for significantly less water (up to 90% less in some instances).

Reducing the water consumption of the system will also reduce the frequency of top-up required, reducing operator dead-time, which can sometimes prove a greater benefit than the actual water savings.

124

Activity/Area Typical Water Consumption

Potential Savings

Comments/Actions

Welfare Blocks 158 m3/month 32 m3/month (20% reduction)

The actual water consumption of the welfare blocks was not quantified, and the figure shown is an approximation based on 220 FTE staff and a consumption of 40 litres per person per day, minus a 25% allowance due to the use of waterless urinals (i.e. 10 l/p/d)

The flow rate of Wash Hand Basins (WHBs) fed directly from mains will vary with the mains pressure, and thus the site currently has little control over their water consumption. Consideration is being given to installing variable Pressure Reduction

Valves (PRVs) at strategic locations around the distribution network to improve control. Two WHBs were monitored, and flow rates were found to be 7.3 litres/minute and 8.0 litres/minute - a good practice flow rate is < 5 litres/minute.

In general, percussion (push) taps were in use, which can be considered good practice. However, the operating times varied from WHB to WHB, and in some instances were excessive (i.e. > 10 seconds). The site is to undertake a review of each WHB to limit the operating time to a

maximum of 5 seconds.

Road Sweeper 35 litres/minute (typical flow capacity of Johnston Sweeper 650 spray systems) 62 m3/month

19 m3/month (30% reduction from spray systems) - this figure assumes the water use associated with the high pressure washer is relatively insignificant.

A single Johnston Sweeper 650 (containing a 1,300 litre water tank) was in use on site, which utilises a front-loaded spray bar and single spray nozzle adjacent to the side channel brush. The operator has on/off control of each of these spray systems, and can also vary the flow rate from within the cab, and as such the road sweeper can be considered relatively water efficient. The system also has a high pressure washer.

The monthly consumption has been estimated based on an average top-up frequency of 2 per day - this figure could vary significantly depending on a number of different factors (e.g. weather, sit conditions, etc.).

Some road sweepers (including this model) have an optional water recirculation system (though it was not fitted in this instance), whereby a portion of the recovered wastewater is filtered and then transferred to the clean water tank. This can provide water savings of up to 50%, though a figure of 30% may be more realistic.

Reducing the water consumption of the system will also reduce the frequency of top-up required, reducing operator dead-time, which can sometimes prove a greater benefit than the actual water savings.

125

Activity/Area Typical Water Consumption

Potential Savings

Comments/Actions

Hydrodemolition 50 lpm 717 m3/month (maximum)

None identified.

The instantaneous flow shown relates to the operation of a single hydrodemolition system, and based on the limited number of systems which have been assessed at other sites, this would appear to be typical for concrete removal.

The monthly volume shown is the maximum a single system could use in a month, assuming 10 hours operation per day and 5.5 days operation per week. The actual consumption will vary significantly as hydrodemolition only occurs during some phases of the works,

and even then, not always every working day.

The pressure and flow rate of the system is set to a level which achieves efficient concrete removal, and it is unlikely this could be reduced to achieve water savings. Therefore, the only potential for water savings may be via staff training (to ensure that concrete is demolished as efficiently as possible). However, as hydrodemolition is a relatively high-risk activity, the focus during operation is quite rightly on health

and safety, and training is not expected to represent a practical opportunity for water savings.

Dust Suppression (Stockpile)

Alternative to Manual Hosing for

Dust Suppression

Unknown Up to 90% This activity was not witnessed on site and so could not be fully assessed or quantified. However, manual hosing was reportedly used - this is water inefficient and represents significant opportunity for improvement.

In future instances of dust suppression, the site will consider using fan misting systems - these create a fine mist which offers improved dust suppression for significantly less water (see photograph).

Bentonite Mixing 53 m3/month None identified Water used as ingredient for bentonite mixing accounts for a relatively large water consumption. However, the water content of the mix is strictly controlled for quality purposes and offers little opportunity for improvement.

The cleaning activities associated with the bentonite plant are potentially variable, and could offer opportunity for improvement. However, no specific opportunities were identified during the audit.

Total quantified savings are in the region of 61 m3/month.

126

The following pie-charts summarise the potential savings on offer from some of the actions detailed above:

Summary

The largest barrier to improving water efficiency on site was the lack of quantitative information, due to the use of

unmetered standpipes and a faulty water meter. With the installation of 4 metered standpipes and a sub-meter on the

feed to the wheel wash system, in conjunction with regular meter readings, the site was better able to manage and

improve their consumption. For example, analysis of the data provided by the wheel wash sub-meter helped:

1. Identify and eliminate the presence of a significant overflow 2. Quantify the typical water consumption per vehicle wash 3. Quantify the water savings achieved by reducing the water supply pressure

This one example highlights well the potential benefits from utilising a robust metering and monitoring system on site.

As the total site water consumption was not identified, the percentage savings cannot be estimated. However, there are

a number of areas where significant savings can be (or have been) achieved on site, and reducing total site water

consumption by 20% (as per the SFfC Water Sub-group’s sector target) should not only be achievable, but could be

exceeded by some margin.

127

Based on low, medium and high unit costs for water and wastewater, as per the current UK charging schemes of the

various water and wastewater operators, the following table summarises the potential financial benefits from achieving

the quantified water savings noted above:

Relative Cost of Water &

Wastewater

Combined Water & Wastewater Cost

(£/m3)

Monthly Water Savings

(m3/month)

Annual Water Savings (m3/year)

Annual Cost Savings (£/year)

LOW 1.53

61 732

1,120

MEDIUM 2.81 2,057

HIGH 5.27 3,858

It can be seen that location can have a significant impact on the financial benefits of water efficiency, in instances where water is charged on a volumetric basis.

128

Appendix 13 Site 12: Civil (Airport) Site Site 12, located in England, was audited between November 2011 - April 2012.

Potential savings of approximately 191 m3/month (i.e. a 15% reduction) have been identified from two water efficiency actions alone, and a number of other opportunities (which can’t be quantified at this time) are also noted. The following information applies to the project:

Value of Site (contractors output) £500 million

Footprint Area (m2) Unknown

Typical Site Working Hours

Monday - Friday:

24/7 (with reduced activity overnight) Saturday:

Sunday:

Maximum Number of People on Site 1,182

Phase of Construction See below

Classification Civil Engineering

Project Use Class Airport

Project Type New Build

Construction Type Civil Engineering

Client Type Developer

Contractual Agreement Individual Company

The project consists of 5 phases of work, some of which overlap, as per the following table:

Phase Start Date End Date

Sub-structure October 2010 January 2013

Super-structure July 2011 December 2012

Fit-out September 2011 August 2013

Mechanical, Electrical & Plumbing July 2011 August 2013

Air-bridges & Fixed Links September 2012 April 2013

All phases of work with the exception of ‘Air-bridges and Fixed Links’ were active during the site audit. The site is operational 24 hours per day, 7 days per week, though there is reduced activity overnight. Staff numbers have gradually increased since the project commenced, with 1,182 staff on site during March 2012 (the largest monthly average to date).

129

Water Consumption Summary Since project commencement, around 22,200 m3 of water has been consumed (up to and inclusive of March 2012 consumption). Consumption is recorded on a monthly basis, and this is summarised in the graph shown below:

The greater consumption in summer months is potentially due (at least in part) to the increased requirement for dust suppression activities. A preliminary analysis of rainfall data for the region was undertaken, to establish whether there

was a clear link between rainfall and the site’s water consumption, but no statistically significant findings were made. As such, there would appear to be a number of other factors which are also significant (e.g. other weather conditions such as temperature, wind, etc.). As can be seen above, analysing water consumption alone does not provide any insight into water efficiency on site - it is generally expected that water consumption throughout the different phases of a construction project will vary, sometimes significantly so, as site operations will regularly change. As such, an increase in water consumption may not necessarily mean water efficiency has reduced (or vice versa). By creating KPIs, which relate site water consumption to some measure of site activity, it can help track water efficiency more accurately. This will not always be a simple process for construction sites, due to the varying nature of site operations - there is not always a practical and available KPI which applies. In this instance, KPIs for project turnover and average staff numbers have been considered:

130

Note: the financial KPIs above have not been adjusted for constant price, whereas the site KPI noted in Section 2 has been to allow comparison with the Constant Price Strategic Forum KPI. There is a significant variation in the KPI values returned, suggesting that on this occasion staff numbers and turnover alone may not be the best measure of expected water consumption. It is likely that the apparent spikes in water consumption are simply due to the operation of some significant water consuming activities, which do not necessarily involve increased staff numbers or turnover, and which are difficult to account for within a KPI.

Water Mass Balance In order to better understand where water is used across the site, a water mass balance has been created, based on data generated/collected during April 2012 - this is summarised in the table below. It is noted that this is a “snap-shot” water mass balance during the stated period, and that it is likely to change (perhaps significantly) over the duration of the project.

Area/Activity Consumption

(m3/month)

Percentage

of Total Comment

North Welfare Block 523 35.5% Sub-meter was installed on supply to building.

South Welfare Block 341 23.1% Consumption estimated at 65% of the North

Welfare Block, which is of similar size but also contains a food preparation canteen.

Draw-off Point A 13 0.9%

Sub-meter installed on supply pipework. Typically used as a back-up supply for road sweeper

top-up. Consumption likely to vary significantly depending

on site conditions, weather, etc.

Draw-off Point B 13 0.9%

Sub-meter installed on supply pipework. Typically used for topping up dust suppression

vehicle. Consumption likely to vary significantly depending

on site conditions, weather, etc.

Road Sweeper Top-up (via Draw-off Point C)

164 11.1%

Consumption estimated based on each vehicle topping up an average of once per day.

Consumption likely to vary significantly depending on site conditions, weather, etc.

Miscellaneous 420 28.5%

‘Miscellaneous’ refers to the remaining water consumption which has not been accounted for by the areas/activities listed above, and includes: o Portion of the water used to top-up dust

suppression vehicle; o Site-based toilet facilities; o Laboratory; o Boot wash; and o Mortar preparation.

TOTAL 1,474

Notes:

It can be seen that the 2 welfare blocks alone accounted for almost 60% of site water consumption over the monitoring period. When considering that the de-centralised welfare facilities (i.e. welfare facilities located amongst actual construction site, rather than within main office areas) are not accounted for within the figure, and thus the actual welfare consumption is likely to be well in excess of 60%, it is clear that the single largest water consuming activity on site during the monitoring period is not actually associated with construction activities.

The dust suppression vehicle, which is typically topped-up through Draw-off Point A, is likely to account for a significant water volume over the duration of the project. However, as the monitoring period was during the wettest April in the UK for around 100 years (i.e. April 2012), and thus the requirement for dust suppression was minimal, this is not accounted for in the water mass balance above.

131

The following is a high level schematic of water distribution around the site:

Water Efficiency Assessment The following table summarises the potential savings which have been identified following the water efficiency assessment which was undertaken:

Problem Solution Potential Savings

Standard (i.e. non-recirculating) road sweepers

Specify recirculating road sweepers 49 m3/month (30% reduction)

Inefficient cleaning operations (e.g. using open hose)

Utilise high pressure washers and/or install trigger-operated spray gun attachments

Unknown but positive

Inefficient stockpile dust suppression Utilise fan misting systems Up to 90% reduction

Large welfare consumption with potential for improvement

Review of domestic and canteen facilities 142 m3/month (25% reduction)

Boot Wash has potential for improvement Consider pressure reduction and improved dry cleaning

30% reduction

Leakage Regular leak detection and repair Variable

Additional details on each opportunity, as well as activities/areas where no opportunity has been identified, are shown overleaf.

North Welfare Block

35.5%

Incoming Water Supply

KEY:

= Water Meter M

South Welfare Block

23.1%

Draw-Off Point A

0.9%

Draw-Off Point B

0.9%

M2 M3

Other

39.6%

M1

132

Activity/Area Typical Water Consumption

Potential Savings

Comments/Actions

Road Sweepers

Misting Dust Suppression Vehicle

35 litres/minute

(typical flow capacity of Johnston Sweeper VT650 spray systems) 164 m3/month

49 m3/month (30% reduction from spray

systems) - this figure assumes the water use associated with the high pressure washers is relatively insignificant.

There are 2 contractors operating road sweepers on site, hereafter referred to as Contractor A and Contractor B. Both contractors utilise Johnston Sweepers.

Contractor A operates 2 VT650 road sweepers, which contain 1,300 litre water tanks.

Contractor B operates 1 - 2 VT800 road sweepers, which contain 1,850 litre water tanks.

The road sweepers utilise a front-loaded spray bar and single spray nozzle adjacent to the side channel brush. The operators have on/off

control of each of these spray systems, and can also vary the flow rates from within the cab, and as such can be considered relatively water efficient. The systems also have a high pressure washer.

One of the Contractor B road sweeper operators reported on/off control of the spray systems only, which is inconsistent with the make/model of sweeper and information provided by Contractor B’s office-based staff. Discussions with Contractor B are on-going to

ensure their road sweeper operators fully utilise the water efficiency capabilities of the systems.

Some road sweepers (including the models noted above) have an optional water recirculation system, whereby a portion of the recovered wastewater is filtered and then recycled to the clean water tank. This can provide water savings of up to 50%, though a figure of 30% may be more realistic. Contractor B is considering a trial of one of these water recirculation systems. Reducing the water consumption of the system will also reduce the frequency of top-up required, reducing operator dead-time, which can sometimes prove a greater benefit than the actual water savings.

Contractor A is considering the use of a settlement pond on site, for wastewater discharge and water abstraction, to reduce or potentially eliminate their mains water requirement.

The typical water consumption shown is based on each road sweeper fillings it tank an average of once per day, though in reality this will vary significantly depending on site conditions, weather, etc.

133

Activity/Area Typical Water Consumption

Potential Savings

Comments/Actions

Vehicular Dust Suppression 234 m3/month None identified.

The vehicle utilised on site, operated by Contractor A, had a 7,700 litre water storage tank, and uses a pump-fed misting (atomising) system to create a more effective water pattern (see photograph). This represents good practice and as a result there is thought to be little opportunity for improvement.

As well as using significantly less water than a traditional “splash-plate” system, typically between 70% - 90% less, the level of dust suppression achieved is normally

increased due to the greatly increased surface area of water.

These systems also reduce the frequency of top-up required, reducing operator dead-time, which can sometimes prove a greater benefit than the actual water savings.

The typical water consumption shown is based on the dust suppression vehicle filling its tank once per day, though in reality this will vary significantly depending on site conditions, weather, etc.

Assuming the dust suppression vehicle in use offers savings of 80% relative to a standard splash-plate system, whilst achieving a similar level of dust suppression, the site may be saving around 936 m3/month by using misting technology.

Cleaning Operations Variable Unknown

There are a variety of cleaning

operations on site, some of which

are good practice (e.g. trigger

operated spray gun within

laboratory) and some of which

could be improved (e.g. open

hose cleaning).

The largest concern was the use

of open hose points for general

cleaning activities, which was

reported but not witnessed during

the site audit. For future cleaning

operations on site, the use of high

pressure washers will be

considered. Where the scale of

use does not merit high pressure

washers, trigger-operated spray

gun attachments will be

considered for installation.

Where the hose points are also

used for large volume filling (e.g.

road sweeper or dust suppression

vehicles) trigger-attached are not

suitable and will not be used.

134

Activity/Area Typical Water Consumption

Potential Savings

Comments/Actions

Dust Suppression (Stockpile)

Alternative to Manual Hosing/ Rain Gun for Dust Suppression

Unknown Up to 90%

Although reported as occurring previously, this activity was not witnessed during the audit, and so could not be fully assessed or quantified. However, manual hosing or larger scale “rain guns” are most commonly used for this application. These are water inefficient and represent significant opportunity for improvement.

In future instances of dust suppression, the site will consider using fan misting systems - these create a fine mist which offers improved dust suppression for

significantly less water (see photograph).

Welfare Blocks

Minimum: 137 m3/month Average: 569 m3/month Maximum: 864 m3/month

142 m3/month (25% reduction)

Welfare water consumption accounts for a significant portion of the site’s total consumption, with over 1,100 staff on site at present (March 2012 figure) using toilet facilities and a full food preparation canteen.

Specific consumption has been estimated as 731 litres per person per month (34 litres per person per day), not including the water consumption of the de-centralised welfare facilities (i.e. welfare facilities located amongst actual construction

site, rather than within main office areas).

As de-centralised welfare water consumption is likely to account for a significant portion of the total welfare water consumption, it is likely that the site’s performance is actually above a typical level of 40 litres per person per day (for sites with a full food preparation canteen).

Urinal cisterns all appeared to be controlled with a hydraulic valve or were of the waterless variety, and as such represent little opportunity for saving.

Wash Hand Basins (WHBs) are likely to account for a significant portion of the welfare water consumption, and represent an opportunity for improvement. The flow rate of WHBs fed directly from mains will vary with the mains pressure, and thus the site currently has little control over their water consumption. Consideration is being given to installing variable Pressure Reduction Valves (PRVs) at strategic locations around the distribution network to improve control. Two WHBs were monitored, and flow rates were found to be 6.4 litres/minute and 6.9 litres/minute - a good practice flow rate is < 5 litres/minute.

135

Activity/Area Typical Water Consumption

Potential Savings

Comments/Actions

Welfare Blocks (Cont'd)

In general, percussion (push) taps were in use, which can be considered good practice. However, the operating times varied from WHB to WHB, and in some instances were excessive (i.e. > 10 seconds). The site is to undertake a review of each WHB to limit the operating time to a maximum of 5 seconds.

The large food preparation canteen, which serves food for up to 1,200 staff each day, will consume large quantities of water. The site is to undertake a focused review of

water using activities within the canteen.

Boot Wash

Variable Flow & Spray Patterns from Boot Wash

Unknown 30% reduction

There is a row of trigger-operated spray guns located at the site entrance, which have a variable spray pattern (and likely flow) depending on the level of trigger depression (see photographs). Each berth also has a brush for dry-cleaning. Whilst the variable flow/spray pattern is good practice, there is still potential for improvement.

Consider installing variable Pressure Reduction Valve (PRV) to

manage and reduce the water pressure to the area, which currently appears slightly excessive.

Install signage to promote use of dry cleaning, thus reducing the level of subsequent wet cleaning which is required.

Leak Detection & Repair

Leaking Decommissioned Draw-off Point

N/A Variable

As with most construction sites, a

number of leaks were present,

and this represents an opportunity

for improvement. For example, a

decommissioned draw-off point

which hadn’t been used in several

months was observed to be

leaking continuously (see

photograph). This is to be

repaired.

Henceforth, the site is to

undertake monthly walk rounds

for the purposes of identifying

(and subsequently repairing) leaks

in the water distribution system.

136

Activity/Area Typical Water Consumption

Potential Savings

Comments/Actions

Bentonite Mixing Unknown Expected to be minimal

This water using activity was not active during the site audit, and so could not be assessed fully.

Water used as ingredient for bentonite mixing accounted for a relatively large amount of site-based water consumption at the time. The site reported that as the mains capacity was insufficient this water was provided by road tanker (and thus is not accounted for in the mains water consumption noted above).

Typically, the water content of a bentonite mix is strictly controlled

for quality purposes and offers little opportunity for improvement.

Mortar Silos Unknown Expected to be minimal

As with bentonite mixing, ingredient water for mortar preparation is strictly controlled for quality purposes and offers no opportunity for saving. With regards to the associated cleaning activities, ensuring the water supply is isolated as soon as the water “runs clear” during pipe flushing will help to minimise water waste.

Laboratory Unknown Expected to be minimal

Water was used within the laboratory for the following purposes: o Open hose for general

cleaning e.g. bucket washing (assessed as part of ‘Cleaning Operations’ above);

o Trigger-operated spray gun for sample washing (good practice);

o 10 x wash baths (periodic replacement dictated by water quality, little opportunity for saving);

o WHB (little opportunity for saving).

Crusher Dust Suppression Unknown Unknown

The crusher system is used to reduce the size of stones/rocks, and requires water for dust suppression purposes.

Although operational at the start of the audit, the plant had been removed from site on subsequent visits when an efficiency assessment was to take place, and so could not be fully assessed.

Total quantified saving are in the region of 191 m3/month.

137

The following pie-charts summarise the potential savings on offer from some of the actions detailed above:

Summary The site is relatively well managed with respect to metering and monitoring, with monthly consumption recording from the main site meter and financial KPI tracking already being undertaken prior the start of the audit. However, due to the large size of the site, the installation of strategically placed sub-meters is crucial to gaining a greater understanding of where water is used around the site, and to allow improvements to be made. As part of the audit, sub-meters were installed on the North Welfare Block, as well as 2 commonly used draw-off points, which allowed creation of the Water Mass Balance noted above. To improve this mass balance further, an additional sub-meter is to be installed on the South Welfare Block, to more accurately quantify its consumption. As welfare water consumption is often the largest water

consuming activity on a construction site, splitting the consumption between welfare and site provides a much clearer understanding of water use on site. Potential savings of around 191 m3/month have been identified from road sweeper and welfare based opportunities alone, which corresponds to around 15% of the total site water consumption. Therefore, taking into account the other opportunities for savings which have been identified but cannot be quantified at this time, achieving a 20% reduction in the site’s water consumption (as per the SFfC Water Sub-group’s sector target) should be achievable. Based on low, medium and high unit costs for water and wastewater, as per the current UK charging schemes of the various water and wastewater operators, the following table summarises the potential financial benefits from achieving the quantified water savings noted above:

Relative Cost of Water &

Wastewater

Combined Water & Wastewater Cost

(£/m3)

Monthly Water Savings

(m3/month)

Annual Water Savings (m3/year)

Annual Cost Savings (£/year)

LOW 1.53

191 2,292

£3,507

MEDIUM 2.81 £6,441

HIGH 5.27 £12,088

It can be seen that location can have a significant impact on the financial benefits of water efficiency, in instances where water is charged on a volumetric basis.

www.wrap.org.uk/construction