Treatment Process Design Calculations

B.Eng(Hons) Civil Engineering

Group One Project Management Expertise, Technology, Results

Treatment Process Works

Design Calculations

Client Revision Date Compiled Checked Approved

Board of Management AIT A 16/04/2013 LM JC FK

C/o Group One Consulting Engineers Ltd, Athlone, Co. Westmeath

Group One Project Management

i

Contents

Contents ................................................................................................................................ i

1 Primary settlement tank design .................................................................................... 1

1.1 Introduction ........................................................................................................... 1

1.2 Hydraulic Sizing ...................................................................................................... 2

1.3 Geotechnical Design: Uplift (EC7) .......................................................................... 3

1.4 Structural Design (EC 2) ......................................................................................... 4

2 PFBR unit outline design ............................................................................................... 7

Media chamber sizing ...................................................................................................... 7


1

1 Primary settlement tank design

1.1 Introduction

The primary settling tank for this facility will consist of 2 sections:

1. Settling chamber

2. Buffer tank

The use of published Environmental Protection Agency (EPA) guideline documents in the

assistance of the design simplifies the design process considerably. The design document

for this design will be the ‘Treatment Systems for Small Communities, Business, Leisure

Centres and Hotels Wastewater Treatment Manual’ for hydraulic sizing.

The design includes geotechnical design for the ULS of uplift according to:

BS EN 1997 – 1

Reinforced concrete design according to:

BS EN 1992 – 1

This report is to be read with reference to the following drawing:

13_AD_007 Primary Settlement Tank Design


2

Job Title: Primary Settlement Tank

Job No. AITWWTF Sheet 1 0f 5

Made By: Luke Molloy Date: 13/04/2013

Structure Ref:

1.2 Hydraulic Sizing

Checked by: FK Date: 15/04/2013

Approved by: JC Date: 15/04/2013

Reference Calculations Output

EPA Design Manual Table 3 $4.1.1 Eqn. 2 Eqn. 3

Wastewater characterisation : For schools that are non-residential and have cooking onsite the following loadings are recommended: Hydraulic loading = 60 litres/day/person Biological loading (BOD5) = 30g/day/person Proposed design parameters: Population equivalent (PE) = 500 Conventional primary settlement tank design: Horizontal tank base area The minimum surface area of the settlement tank is equated as follows:

A =

x P 0.85 = 19.68m2

This value is based on dry weather flow (DWF) of 180l/person so to allow for the reduced value of 60l/person/day the figure is modified by a conservative 0.5 Modified A = 19.86 x 0.5 = 9.84m2

Horizontal tank capacity The capacity of the primary settlement tank can be equated as follows: C = 180 x P0.85 = 35432 litres Modified capacity for 60l/person/day = 17716 litres Tank dimensions Taking a ratio of length = 3 x width Width = 1.8m Length = 5.4m Height = 2.5m Allowing 400mm min clearance from top water level to top of tank

Tank area = 9.84m2 Tank Vol =18m3


3




Structure Ref:

1.3 Geotechnical Design: Uplift (EC7)




EN 1997 -1 $2.4.7.4 Eqn. 2.8 National Annex, A Table A.1

Verification for uplift (UPL) shall be carried out by checking that the design value of the combination of destabilising permanent and variable vertical actions (Vdst) is less than or equal to the sum of the design value of the stabilising permanent vertical actions (Gstb) Vdst,d Gstb,d Vdst,d = L Gstb,d =

These values are design values hence partial safety factors are required for ULS Required partial safety factors γg,dst = 1.1 γg,sta = 0.9

Taking the unit as a whole and water level at a height of 1.5m from the base of the tank: Vdst,d = 1.1 x 10 x 1.5 x 5.2 x 6.2 = 531.96 kN Gstb,d = 0.9 x 25 x 38 = 855 kN Vdst,d Gstb,d therefore tank satisfies the uplift condition

Uplift OK


4




Structure Ref:

1.4 Structural Design (EC 2)




EN 1992-1 Table NA.7 EN 1992 – 1

This design is based on the longest wall of the tank and based on the external drained active soil pressure against it while the tank is empty. Wall dimensions = 6.2m x 2.5m g = gravity = 9.81m/s2 Assumed values for soil: Ka = 0.27, active earth pressure coefficient (Ranking) ρs = 19kN/m3, soil weight ρw = 10kN/m3, weight of water fyk = 500N/mm2, characteristic tensile strength of steel fck = 30N/mm2, characteristic compression strength of concrete (class designation XD2) Surcharge load = 10kN/m2 Partial safety factors: γf = 1.35 at ULS for permanent loads Horizontal of soil on wall: Hsoil = γf x ρs x Ka x g x h2 x 0.5 = 212kN Hsurcharge = γf x Ka x h x surcharge = 9.11kN Hsoil acts h/3 lever arm Hsurcharge acts h/2 lever arm MED = design applied bending moment: MED, Soil = 212 x 0.84 = 178.1kNm MED, Surcharge = 9.11 x 1.25 = 11.4kNm MED, Total = 178.1 + 11.4 = 190kNm This moment is used as the moment needed to provide resistance to by the reinforcement steel in the tank wall

MED, = 190kNm


5




Structure Ref: Structural Design (EC 2) Contd.




EN 1992 – 1 EN 1992-1 Table NA.7

Longitudinal reinforcement: Walls Breath of member = 2500mm Height of member = 400mm Cover required = 50mm (class designation XD2) Assumed bar size = 20mm diameter Effective depth to reinforcement = 340mm

K =

= 0.022

z/d = 0.5(1+√ ) = 0.98

limit z/d to 0.95 z = 0.95 x d = 323mm Required area of steel reinforcement is given by:

As = 1285mm2 Provide 15 No. H12 @180mm spacing to be provided on both faces and also as longitudinal reinforcement. See drawing No 13_AD_

Base Assuming worst case of water pressure uplift on the base = FED

= 1.5 x 10 x 5.2 x 6.2 x 1.35 = 653kN This acting along the short span gives: 653/6.2 = 105kN/mrun, use for MED as w l = 6.2m MED, = wl2/8 = 504kNm

MED = 504kNm

zf87.0

MA

yk

Eds


6




Structure Ref: Structural Design (EC 2) Contd.




EN 1992 – 1

Base depth = 500mm Effective depth = 440mm Z = 0.95 x 440 = 418mm As = 2771mm2 Provide 9 No. H20 bars @ 125mm spacing This can be provided as transverse steel also. Central dividing wall In a similar process to the external walls except using the wall height as depth of water considering worst case if only one compartment of the tank is completely full and the other is completely empty. Fw = force from water FW = γf x ρw x g x h2 x 0.5 = 414kN Acting h/3 from base MED = 348kNm As = 2477mm2

Provide 15 No. H16 @ 180mm spacing Provide H16 @ 200mm spacing transverse

MED = 348kNm


7

2 PFBR unit outline design

Job Title: Pumped Flow Biofilm Reactor Tanks


Made By: Jason Corbett Date: 13/04/2013

Structure Ref:

Media chamber sizing


Approved by: LM Date: 15/04/2013


Hewitech CF 25 Product Data Sheet

Flow to unit: 60 litres per person per day for 500 PE = 30,000l/day Unit operates for 3 cycles at 10,000l per cycle Unit volume = 10,000l Media occupy 96% of tank volume: 10,000 x 1.04 = 10.4m3 with an increase to 11m3 due to microbial growth on media Estimated tank dimensions given clearance of 0.8 metres Tank dimensions: Height = 2m Breadth = 2.3m Length = 4m Allowing for a base thickness of 0.5m and a wall thickness of 0.4m and a cover plinth of 0.2m the overall tank dimensions are: Height = 2.7m Breadth = 3.1m Length = 4.8m These are the dimensions for each tank. There are two tanks involved in this process.

Tank dim: H = 2.7m B = 3.1m L = 4.8m

Treatment Process Design Calculations

Documents

Transcript of Treatment Process Design Calculations