RESULTS OF THE COMPREHENSIVE...

11/3/2017 - 1 - Final PWSA CPE Report

RESULTS OF THE

COMPREHENSIVE PERFORMANCE EVALUATION

FOR THE

PITTSBURGH WATER & SEWER AUTHORITY

ASPINWALL WATER FILTRATION PLANT

PITTSBURGH, PENNSYLVANIA

SEPTEMBER 18 – 22, 2017


Prepared By:

Pennsylvania Department of Environmental Protection

Rachel Carson State Office Building

400 Market Street

Harrisburg, Pennsylvania 17101

US Environmental Protection Agency Region III

Water Protection Division

Office of Drinking Water and Source Water Protection

1650 Arch Street

Philadelphia, Pennsylvania 19103

US Environmental Protection Agency Office of Water

Office of Ground Water and Drinking Water

Standards and Risk Management Division

Technical Support Center

26 W. M.L. King Drive

Cincinnati, Ohio 45268

Process Applications, Inc.

2627 Redwing Road, Suite 340

Fort Collins, Colorado 80526


Table of Contents

Page No.

SITE VISIT INFORMATION 6

INTRODUCTION 8

DESCRIPTION OF WATER TREATMENT PLANT 9

Overview 9

Water Treatment Processes 10

PERFORMANCE ASSESSMENT 12

Historical Performance Assessment 12

Performance Summary 27

Special Studies 28

MAJOR UNIT PROCESS EVALUATION 51

PERFORMANCE-LIMITING FACTORS 57

FACTORS SUMMARY CHART 57

“A” FACTOR EXAMPLES 58

“B” FACTOR EXAMPLES 66

“C” FACTOR EXAMPLES 69

APPENDIX

MPA RESULTS 71

PWSA ORGANIZATIONAL CHART 74


List of Figures Page No.

FIGURE 1 Process Flow Schematic of the Aspinwall Plant 10

FIGURE 2 Filter Effluent Configuration 14

FIGURE 3 OAS Turbidity Data Profile 17

FIGURE 4 Daily Maximum Clarified and Settled Turbidity Trends 18

FIGURE 5 Daily Maximum IFE and CFE Turbidity Trends 18

FIGURE 6 Filters 2 and 17 IFE Maximum Daily Turbidity Trends 21

FIGURE 7 Giardia Inactivation Ratio Calculated by CPE Team 25

FIGURE 8 CPE Calculated & PWSA Reported Giardia Inactivation Ratios 26

FIGURE 9 Filter 18 Waste Backwash Water Turbidity Profile 31

FIGURE 10 Example Filter 18 Flow Anomaly During Backwash Event 32

FIGURE 11 Filter 18 Recovery Curve Following Backwash 33

FIGURE 12 Turbidimeter Flow Rate vs. Manufacturer Specifications 37

FIGURE 13 Turbidimeter Sample Detention Time Check 38

FIGURE 14 Filter 12 IFE Turbidity Profile January 24-25, 2017 41

FIGURE 15 North and South CFE Turbidity August 31, 2017 42

FIGURE 16 Raw, Settled, & Clarified Turbidity Comparison 44

FIGURE 17 North CFE, South CFE, Filter 9 and Filter 16 IFE Turbidity 45

FIGURE 18 Water Quality Grab Sample Results 49

FIGURE 19 Total Manganese Trend at Each Unit Process 50

FIGURE 20 Major Unit Process Evaluation 52


List of Tables

TABLE 1 CPE Turbidity Performance Analysis Data Acquisition Description 13

TABLE 2 OAS Summary Statistics 16

TABLE 3 IFE Turbidity 95th Percentile by Month for Each Filter 20

TABLE 4 Backwash Return to Service Performance 22

TABLE 5 Individual Backwash Recovery and Filter Performance 23

TABLE 6 Aspinwall Treatment Plant Performance Summary 27

TABLE 7 Filter 18 Backwash Description 28

TABLE 8 Turbidimeter Settings 39

TABLE 9 Online Chlorine Analyzer Settings Check 46

TABLE 10 Results of Coagulant Dosage Evaluation 47

TABLE 11 Coordinated Water Quality Grab Sample Results 48

TABLE 12 Summary of Performance Limiting Factors 57


SITE VISIT INFORMATION

Site and Mailing Address:

Pittsburgh Water & Sewer Authority Aspinwall, Pennsylvania 15215

Date of Site Visit:

September 18 - 22, 2017

Aspinwall Plant Personnel Participating:

Robert Weimar – Interim Executive Director

Alex Sciulli – Consultant to Water Production Team

Deb Lestitian – Chair, PWSA Board

Kate Mechler – Program Manager, Capital Programs

Jim Paparocki – Maintenance Manager, Water Production

Jeff Turko – Operations Manager, Water Production

Faith Wydra – Environmental Compliance Manager

Mike Czypinski – Acting Laboratory and Compliance Manager

Dr. Stanley States – Operations Consultant, Texas A&M

Terry Campbell - Maintenance Consultant, Optimum Controls Corp.

Kent Lindsay - Director of Finance


CPE Team:

Larry DeMers – Process Applications, Inc., 2627 Redwing Rd., #340, Ft. Collins, CO 80526

970-223-5787; [email protected]

Bill Davis – Process Applications, Inc., 2627 Redwing Rd., #340, Ft. Collins, CO 80526


Jennifer Bunton – Process Applications, Inc., 2627 Redwing Rd., #340, Ft. Collins, CO 80526


Rick Lieberman – US Environmental Protection Agency, Technical Support Center, 26 W. M.L. King

Drive, Cincinnati, OH 45268, 513-569-7604, [email protected]

Alison Dugan – US Environmental Protection Agency, Technical Support Center, 26 W. M.L. King


Matt Alexander – US Environmental Protection Agency, Technical Support Center, 26 W. M.L. King


Kelly Moran – US Environmental Protection Agency, Region 3, 1650 Arch Street, Philadelphia, PA

19103-2029, 215-814-2331, [email protected]

Rick Rogers – US Environmental Protection Agency, Region 3, 1650 Arch Street, Philadelphia, PA

19103-2029, 215 814-5711, [email protected]

Ed Chescattie – Pennsylvania Department of Environmental Protection, Rachel Carson State Office

Building, 400 Market Street, Harrisburg, PA 17101, 717-772-2184, [email protected]

Bethany Shrodo – Pennsylvania Department of Environmental Protection, 208 West Third St.

Suite 101, Williamsport, PA 17701, 570-327-3732, [email protected]

Mike Hess – Pennsylvania Department of Environmental Protection, Rachel Carson State Office


Kevin Anderson – Pennsylvania Department of Environmental Protection, Rachel Carson State Office


Renee Diehl – Pennsylvania Department of Environmental Protection, 400 Waterfront Drive, Pittsburgh,

PA 15222, 412 442-4217, [email protected]

John Paone – Pennsylvania Department of Environmental Protection, 400 Waterfront Drive, Pittsburgh,

PA, 724-925-5408, [email protected]

Laura Blood – Pennsylvania Department of Environmental Protection, Address, 724-925-5547,

[email protected]


INTRODUCTION

The Composite Correction Program (CCP)1 is an approach developed by the U. S. Environmental

Protection Agency (USEPA) and Process Applications, Inc. (PAI) to improve surface water

treatment plant performance and to achieve compliance with the Surface Water Treatment Rule

(SWTR). Its development was initiated by PAI and the State of Montana2, which identified the

need for a program to manage performance problems at its surface water treatment plants.

A Comprehensive Performance Evaluation (CPE) is a thorough evaluation of an existing

treatment plant, resulting in a comprehensive assessment of the unit process capabilities and the

impact of the operation, maintenance, and administrative practices on performance of the plant.

The results of the evaluation establish the plant capability to consistently meet the optimization

goals and list a set of prioritized factors limiting performance. Follow up technical assistance

can be used to improve performance of an existing plant by systematically addressing the factors

limiting performance identified during the CPE.

The federal Surface Water Treatment Rule (SWTR), Interim Enhanced Surface Water Treatment

Rule, and Long-Term 1 Enhanced Surface Water Treatment Rules require plants to achieve less

than 0.3 NTU (nephelometric turbidity units) in 95 percent of the monthly combined filter

effluent samples and to monitor individual filter performance. The enhanced SWTR

requirements have been in effect for all surface water treatment plants since 2005. Research

results and field experience have shown that achieving 0.3 NTU does not guarantee protection

against some pathogenic microorganisms, as evidenced by some waterborne disease outbreaks.

Producing a finished water with a turbidity of less than or equal to 0.10 NTU provides much

greater protection against pathogens like Cryptosporidium. This microorganism passed through

the public water supply and was responsible for a large outbreak of Cryptosporidiosis in

Milwaukee, Wisconsin, in April 1993, where 400,000 people became ill and nearly 100 died.

1 Hegg, B.A., L.D. DeMers, J.H. Bender, E.M. Bissonette, and R.J. Lieberman, Handbook - Optimizing Water Treatment Plant

Performance Using the Composite Correction Program, EPA 625/6-91/027, USEPA, Washington, D.C. (August 1998).

2 Renner, R.C., B.A. Hegg, and D.F. Fraser, Demonstration of the Comprehensive Performance Evaluation Technique to Assess

Montana Surface Water Treatment Plants, Association of State Drinking Water Administration Conference, Tucson, AZ

(February 1989).


Cryptosporidium oocysts are extremely resistant to chlorine disinfection, necessitating properly

operated physical removal barriers. Studies have shown that when filter effluent turbidities

exceed 0.10 NTU, the likelihood of Cryptosporidium breakthrough increases.

This CPE was conducted at the Pittsburgh Sewer and Water Authority’s (PWSA) Aspinwall

Water Treatment Plant (WTP). During the CPE, all aspects of water treatment administration,

data, design, operation, and maintenance were evaluated with respect to their impact on

achieving optimal performance of the turbidity and disinfection barriers. Each unit process at the

Aspinwall WTP up to the entry point was evaluated in this CPE. PWSA also oversees operation

of a membrane filtration plant, the Highland Park plant, which was offline for repairs, and not

included in this CPE.

PWSA Interim Executive Director, Mr. Robert Weimer, was the lead point of contact when

scheduling this CPE. The CPE team would like to thank Mr. Weimer and all the plant staff for

taking the time out of their busy schedules to fully participate in this CPE. During the

evaluation, plant staff members acted in a professional manner, openly discussed current and

past operational practices, and demonstrated a genuine interest in obtaining input on methods to

improve future plant performance. This type of positive attitude represents a solid foundation for

tackling the current and future challenges that PWSA is working to resolve. This report

documents the findings of the CPE conducted at the PWSA Aspinwall WTP on September 19-

21, 2017.

DESCRIPTION OF WATER TREATMENT PLANT

Overview

The PWSA Aspinwall WTP supplies potable water for approximately 80percent of the City of

Pittsburgh and Millvale Borough and sells bulk water to Reserve Township, Fox Chapel

Authority, Aspinwall Borough, and the Hampton Shaler Water Authority, all in southwestern

Pennsylvania. The plant is designed to treat source water from the Allegheny River through

coagulation, flocculation, clarification, sedimentation, filtration, and disinfection.


From the influent stilling basin, water flows through two traveling screens. After the screens,

ferric chloride is added in a common trough prior to rapid mix. The water then flows through

four constant speed flash mixers in series. Lime is added to the first chamber, and cationic

polymer is added to the third chamber. Caustic soda and/or activated carbon can be fed into each

of the rapid mix chambers. The estimated contact time in each mixer was approximately 30

seconds according to the PWSA engineering consultants.

From the rapid mix basins, water flows by gravity to four flocculation and clarification basins.

Each clarification unit includes two, 2-stage flocculators and a conventional sedimentation basin

(referred to as a “clarifier” by PWSA staff). The flocculators are operated at constant speed.

Waste sludge is scraped from the bottom of the sedimentation basin, via an automated removal

system, and sent to the clarifier residual distribution chamber. Clarifier effluent water flows over

weirs and is sent to a central receiving basin where the flow is split to two large uncovered

concrete sedimentation basins. There is no automated sludge removal mechanism provided for

these basins. From the sedimentation basins, water flows to the filter building; chlorine and

cationic polymer are added prior to the filter splitter box.

From the splitter box, water flows to 18 dual media (18 inches anthracite and 12 inches sand)

filters. Flow onto the filters is controlled by modulating valves on the individual filter effluent

lines. Each filter has two cells. The cells have separate underdrain systems and are washed

independently.

Each filter is backwashed just prior to approximately 100 hours of run time. Filtered water is

used for backwashing, but the distribution system water can also be utilized for backwashing as

long as adequate distribution system pressure is available (e.g. not available while Lamphur

reservoir is offline). Backwash begins with air scour, followed by combined air and water wash,

high rate water only wash, and then ETSW. Spent backwash water is sent to the backwash

storage tank. This plant has always had filter to waste capabilities, but just recently began using

filter to waste; water filtered to waste is sent to the backwash storage tank. Supernatant from the

backwash storage tank is recycled to the East intake stilling basin constantly at a rate of five

percent (capacity exists to recycle at a rate of 10 percent). Each filter has one individual filter

effluent sample line that carries a sample stream to a Hach 1720E turbidimeter. The current


location of sample taps leaves one cell of each filter unmonitored. The filters discharge into an

effluent pipe where chlorine is added for disinfection.

PERFORMANCE ASSESSMENT

Historical Performance Assessment

To achieve optimized performance, a water treatment plant must demonstrate that it can take a

raw water source of variable quality and produce consistent, high quality finished water.

Further, the performance of each unit process must demonstrate its capability to act as a barrier

to the passage of particles at all times.

The CPE team used turbidity data collected from the Aspinwall plant’s continuous reading

turbidimeters and laboratory log sheets (representing grab sampling results) to assess the

effectiveness of the flocculation/clarification/sedimentation and filtration barriers. The turbidity

data used in the performance evaluation were collected over a 12-month period, starting

September 19, 2016 and ending September 18, 2017. The CPE team also used Giardia log

inactivation calculations to assess the performance of the disinfection barrier. The data used to

assess the disinfection barrier were obtained from the spreadsheet PWSA is using to report their

Redacted-Security Issue


daily log inactivation to PA DEP as well as data from the Pennsylvania Drinking Water

Information System (PADWIS). Disinfection data were only available from the time period

May 5 through August 31, 2017. See Table 1 for a discussion of the data sources used in the

CPE performance analysis.

TABLE 1. CPE Performance Analysis Data Acquisition Description

Performance Parameter Data Used in the CPE Performance Analysis

Raw water turbidity Data were taken from daily log sheets kept in the Aspinwall laboratory.

Records were not available for the time period between September 19

and October 31, 2016. Lab personnel collect raw water turbidity grab

samples once per day from a sample location in the river, prior to the

water being exposed to permanganate. There is a continuous analyzer

that measures raw water turbidity prior to coagulant addition but the

continuous data were not used for this analysis due to the presence of

permanganate in the water at the sample point, potentially affecting the

turbidity measurement, and the “capping” of the continuous data at 100

NTU. The grab sample data were not “capped”.

Clarifier turbidity Data were taken from fifteen-minute readings extracted from the plant

Supervisory Control and Data Acquisition (SCADA) system. The

clarifier continuous turbidity sample location is on the combined

clarifier flume prior to leaving the clarification building and prior to the

transmission line to the settling ponds, so the readings represent the

turbidity from the mixed water coming from all the clarifiers in

operation.

Settled water turbidity Data were taken from one-minute readings extracted from the plant

SCADA system. The settled water continuous turbidity sample

location is on the transmission line from the settling ponds, so the

readings represent the turbidity from the mixed water coming from both

ponds.

Individual Filter Effluent

(IFE) turbidity

Data were taken from fifteen-minute readings extracted from the plant

SCADA system. The IFE continuous turbidity sample location at each

filter is located on a manifold line that connects two separate filter

cells. The meter is generally closest to the filter cell furthest from the

filter effluent line. A filter effluent configuration diagram showing the

approximate IFE turbidity sample location for a typical filter is

provided in Figure 2. The data extracted from the SCADA historian

was further processed by the CPE team to attempt to exclude data that

represented turbidity during times when the filter was not in service.

This was done by reviewing the filter flow rate (also extracted from the

SCADA historian) and excluding all turbidity data when the flow rate

seemed to be at or near zero. Due to anomalies in the filter flow rate

data (See Special Study 2 and Figure 10) the turbidity values occurring

when the flow read 1.3 MGD or below were excluded. Post backwash


Turbidity Evaluation

Raw water, settled water, IFE, and CFE turbidity data were entered into an Optimization

Assessment Spreadsheet (OAS), and analyzed through the spreadsheet calculations and charts.

Table 2 shows the OAS summary statistics for the plant.

The statistics in Table 2 show the maximum daily values for raw, settled, IFE, and CFE turbidity

during the September 19, 2016 to September 15, 2017 period, along with a comparison to

optimization goals. For optimization purposes, the maximum daily turbidity readings are used to

show the daily worst case performance by each of the barriers. If the plant can perform within

the optimization goals at the time of its worst daily performance, then the plant staff can be

assured that it is also meeting the goals during the rest of the day and providing the maximum

public health protection. Table 2 shows that the annual average daily maximum raw water

turbidity for the Aspinwall WTP was 16.1 NTU. For raw water conditions such as this, where

the annual average daily maximum raw water turbidity is above 10 Nephelometric Turbidity

Units (NTU), the optimization goal for settled water turbidity is ≤ 2.0 NTU in 95 percent of daily

readings. The daily maximum clarified water and settled water turbidity met the optimization

goal on only 0.3 and 52.2 percent of the days respectively. The daily maximum clarified water

turbidity was ≤ 10.0 NTU in 95percent of the days and the daily maximum settled water turbidity

was ≤ 5.0 NTU on 95 percent of the days during the evaluation period. It should be noted that

both of these statistics were derived from data that had been “capped” by the SCADA system

historian so the actual 95th percentile of both readings was higher. Table 2 shows that the daily

maximum IFE turbidity values (labeled as “max. filtered turbidity”) met the optimization goals

on about 10.7 percent of the days analyzed. The daily maximum IFE values were 0.52 NTU or

less on 95 percent of the days analyzed. The daily maximum CFE values (labeled as “combined

filtered turbidity”) met the optimization goal of 0.10 NTU on 66 percent of the days analyzed;

CFE values were 0.83 NTU or less during 95 percent of the days in the period.


TABLE 2. OAS Summary Statistics

RSQ = Correlation Coefficient for two selected data-sets (>0.25 suggests correlation).

95percent = 95th percentile value for data-set.

Opt. Goal = Percent of values in data-set that are less than or equal to the selected optimization turbidity goal.

Reg. = Percent of values in data-set that are less than or equal to the regulated turbidity requirement.

While Table 2 provides a summary of the plant’s turbidity performance compared to the

optimization goals, Figure 3 provides a visual representation of the plant turbidity profile

compared to the optimization goals. The figure shows that higher raw water turbidity values

occurred intermittently throughout the year. The lowest clarified water turbidity values tended to

occur when the raw water turbidity was also low, around late October and early November 2016

but the clarifier performance was inconsistent all year and reached the data cap of 10 NTU on

many occasions. The settled water turbidity tended to be lower than the clarified water turbidity

but it also reached its data cap often, so the maximum settled water turbidities for many days

cannot be reliably verified as lower than the clarified water turbidity. The data cap for clarified

water was 10 NTU and the data cap for settled water was 5 NTU. Capping of these data would

skew the RSQ result such that any correlation between raw water turbidity spikes and clarified

water spikes would not be accurately measured. Passage of turbidity spikes from the raw

through the clarifiers and/or the sedimentation ponds would represent the potential for higher

risk of pathogens passing through the treatment barriers. Data capping prevents the ability of the

PWSA plant staff to assess that risk. The data capping of the clarified turbidity and settled water

turbidity is more evident when those two trends are isolated in Figure 4. Figure 4 also shows

performance relative to the settled water turbidity goal for the settling processes.

Avg Min Max RSQ 95% Opt. Goal Reg.

NTU NTU NTU NTU % Values % Values

Raw Turbidity 16.1 2.0 147.0 n/a 51.7 n/a n/a

Max. Clarifier Turbidity 7.1 2.0 10.0 0.00 10.0 0.3 n/a

Max. Settled Turbidity 2.5 0.1 5.0 0.00 5.0 52.2 n/a

Max. Filtered Turbidity 0.20 0.04 1.03 0.00 0.52 10.7 n/a

Combined Filtered Turbidity 0.17 0.04 1.00 0.02 0.83 66.4 85.8

ANNUAL DATA


Table 3 shows the 95th percentile turbidity values for each filter by month and summarizes the

entire year of the study period. Blank cells in the table indicate no turbidity data was available

from the 15-minute SCADA extraction for that time period. The CPE team assessed the filter

rehabilitation project schedule and confirmed that the lack of turbidity data during those time

periods were due to the filters being out of service for upgrading. The highest 95th percentile

value for each month is shown in red in the table. Table 3 shows filter 2 was the only filter to

meet the ≤ 0.10 NTU optimization goal 95percent of the days evaluated. Filter 17 was the

worst performing filter, meeting the goal only 71.5 percent of the days during the evaluation

period. The 95th percentile for filter 17 was ≤ 0.24 NTU. Filter 12 had the worst performance

for three consecutive months during the December to February period. As a comparison, the

annual maximum daily turbidity data from Filters 2 and 17 are shown in Figure 6. The filter 2

trend line in Figure 6 is less erratic than the trend line for filter 17, indicating more consistent

performance. It also shows a trend that is more consistently below the goal of ≤ 0.10 NTU.


TABLE 3. IFE Turbidity 95th Percentile by Month for Each Filter

Filtered Water Turbidity95th Percentile Values (NTU)

Filter 1 Filter 2 Filter 3 Filter 4 Filter 5 Filter 6 Filter 7 Filter 8 Filter 9 Filter 10 Filter 11 Filter 12 Filter 13 Filter 14 Filter 15 Filter 16 Filter 17 Filter 18 Combined

Sep-16 0.24 0.73 0.15 0.13 0.11 0.15 0.13 0.09 0.12 0.12 0.15 0.11 0.29 0.16 0.35

Oct-16 0.10 0.14 0.19 0.12 0.14 0.12 0.10 0.13 0.15 0.26

Nov-16 0.08 0.17 0.12 0.42 0.16 1.00 0.22 0.28 0.17 0.17 0.28 0.96

Dec-16 0.07 0.12 0.12 0.13 0.14 0.15 0.15 0.18 0.12 0.14 0.17 0.68

Jan-17 0.09 0.12 0.19 0.13 0.15 0.14 0.16 0.61 0.17 0.15 0.15 0.82

Feb-17 0.11 0.16 0.14 0.18 0.11 0.17 0.16 0.30 0.14 0.18 0.11 0.84

Mar-17 0.09 0.14 0.15 0.14 0.12 0.17 0.16 0.11 0.12 0.21 0.11 0.78

Apr-17 0.08 0.12 0.11 0.20 0.12 0.11 0.16 0.11 0.11 0.14 0.17 0.13 0.16 0.13 0.70

May-17 0.09 0.14 0.14 0.21 0.14 0.17 0.14 0.18 0.24 0.22 0.28 0.19 0.25 0.17 0.14

Jun-17 0.10 0.08 0.12 0.23 0.39 0.20 0.20 0.16 0.20 0.17 0.18 0.28 0.32 0.13 0.97

Jul-17 0.08 0.09 0.11 0.14 0.09 0.13 0.17 0.24 0.09 0.14 0.11 0.13 0.16 0.65 0.13

Aug-17 0.10 0.04 0.27 0.13 0.10 0.16 0.17 0.17 0.09 0.10 0.13 0.12 0.16 0.17 0.47

Yr. 95% 0.09 0.14 0.16 0.19 0.13 0.17 0.16 0.18 0.17 0.15 0.17 0.16 0.24 0.17 0.83

Yr. Goal 96.7% 84.7% 82.2% 78.7% 85.5% 80.0% 75.9% 85.1% 88.9% 84.7% 77.8% 80.5% 71.5% 73.7% 66.4%


FIGURE 6. Filters 2 and 17 IFE Maximum Daily Turbidity Trends

The optimization goal for individual filters that have filter to waste capability is to filter to waste

following each filter backwash, and return the filter to service with turbidity less than 0.10 NTU

and for the filter performance to remain less than 0.10 NTU for the entire filter run. The

summary statistics from previously discussed Table 2 revealed poor IFE and CFE performance.

Since filter to waste capability was not being utilized, data from the SCADA historian were

available for analysis of filter performance during the ripening period. The 15-minute data from

the SCADA historian were used to document all the backwashes at the Aspinwall plant during

February 2017 (representing a time when water temperatures would be cold and filter recovery

might be a challenge) and during the August 15 to September 18, 2017 period (representing the

most recent time period prior to the CPE site visit). The data were analyzed by trending the filter

effluent flow and filter turbidity data and finding typical backwash spikes after a period with low

flow.

Table 4 summarizes the backwash return to service performance statistics for the time periods

evaluated.

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to achieve and maintain optimized performance. Optimizing the backwash procedure could

reduce the recovery time of the filters and reduce the time necessary for filter to waste.

Disinfection Evaluation

The disinfection treatment process is an important barrier to microorganisms in any surface

water treatment plant. In addition to maintaining adequate turbidity removal via pretreatment

and filtration, the Aspinwall WTP is also required to maintain an additional 90percent (1-log)

inactivation of Giardia cysts, and 99.99percent (4-log) inactivation of viruses in accordance with

Pennsylvania regulations.

To evaluate the disinfection process, the CPE team collected data from the spreadsheet PWSA is

using to report their daily log inactivation to Pennsylvania Department of Environmental

Protection (PA DEP) and the PADWIS to calculate inactivation ratios. This data included

maximum daily flow, minimum daily temperature, maximum daily pH, minimum daily depth of

the clear well, and minimum daily chlorine residual. The inactivation ratio is the concentration

of disinfectant residual times the contact time through the disinfection zone (C x T or CT)

achieved at the plant on a particular day, divided by the CT required (CTreq) to achieve 1.0 log

inactivation of Giardia cysts. The CPE team calculated the plant inactivation ratios for May 5

through August 31, 2017. Graphical representation of the data is depicted in Figure 7.

During a prior evaluation conducted by the PA DEP in April of 2017, the physical characteristics

of the clear well were observed as they related to the baffling factor of 0.48 being used by PWSA

staff for CT calculations at that time. PA DEP staff determined during that evaluation that a

baffling factor of 0.3 was the maximum that could be allowed without a tracer study, given the

clear well design. The PWSA staff immediately implemented use of the 0.3 baffling factor in

plant disinfection calculations. The Giardia inactivation ratios shown in Figure 7 were generated

using a baffling factor of 0.3, data compiled by PWSA for daily calculation of inactivation ratios

(PWSA Log Inactivation Data spreadsheets), and minimum daily entry point chlorine residuals

reported to PADWIS.

As shown in Figure 7, the plant typically was not challenged to meet the required inactivation

ratio during the evaluation period. The inactivation ratio fell below 2.0 in late June due to low


chlorine residual in the clear well. During a CPE, the inactivation ratio would typically be

assessed over the past year, but the CPE team was not able to locate data needed for CT

calculations prior to May 5, 2017. Ideally, the inactivation ratio should be evaluated during the

winter months when the source water has a lower temperature.

FIGURE 7. Giardia Inactivation Ratio Calculated by CPE Team

The inactivation ratios calculated by the CPE team were compared to the inactivation ratios

reported to the PA DEP during the same period. This comparison, shown in Figure 8, indicates

that inactivation ratios reported by PWSA for the Aspinwall WTP were consistently higher than

those calculated by the CPE team. Analysis of the data indicates that the discrepancy may be

due to the way the minimum chlorine residual is being determined each day and to minor

differences in the calculation of minimum daily depth or volume of the clear well. As a result,

the method of determining minimum chlorine residual and minimum clear well volume should

be reviewed to ensure that disinfection requirements are met using accurate and representative

data.


FIGURE 8. Comparison of CPE-Calculated and PWSA-Reported Inactivation Ratios

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Performance Summary

The performance observations described above are summarized in Table 6.

TABLE 6. Aspinwall Treatment Plant Performance Summary

Barrier Optimization Goal Performance

Sedimentation Settled water turbidity 2 NTU or

less 95 percent of the time based

on daily maximum values.

The clarified water turbidity met the settled

water goal only 0.3 percent of the days in the

most recent year. The 95th percentile

turbidity value of the clarified water was

equal to the data cap of 10 NTU. The settled

water turbidity from the settling ponds met

the goals 52percent of the days with a 95th

percentile turbidity value equal to the data

cap of 5.0 NTU. Capping of data prevented

an accurate assessment of raw water turbidity

spikes passing through the clarification and

sedimentation processes.

Filtration IFE and CFE turbidities 0.10 NTU

or less 95 percent of the time based

on daily maximum values.

The daily maximum turbidity values from

the IFE data set show the filters to meet the

optimization goal in 10.7 percent of the days

in the most recent year. The 95th percentile

turbidity value was 0.52 NTU.

The daily maximum values from the CFE

turbidity records in the last year show the

optimization goal to be achieved at the

Aspinwall plant 66.4percent of the days. The

95th percentile turbidity value over that

period is 0.83 NTU.

Disinfection Inactivation ratio above 1-log

every day that the plant is in

operation.

The disinfection process met the inactivation

ratio goal every day during the period

reviewed (May 5 thru August 31, 2017).

Data prior to May 5 was not evaluated as

PWSA staff only recently started tracking

inactivation ratios using a CT spreadsheet

that was provided by PA DEP.


Special Studies

During the CPE, several special studies were conducted for use in assessing plant performance

and process control. These studies included: 1) a filter bed expansion, 2) filter backwash cleaning

efficiency, 3) post-backwash turbidity recovery; 4) microscopic particulate analysis, and 5) turbidity data

integrity assessment, which consisted of four smaller studies 6) online chlorine analyzer setting check 7)

coagulant dosage evaluation, and 8) coordinated water quality grab sampling

Special Study 1: Filter Bed Expansion

For the filter related studies, Filter 18 was selected because it was close to the maximum filter

run time targeted by the operators (i.e., 100 hours) on the day of the study. All the filters have

been recently renovated, and the filter media includes 12 inches of sand and 18 inches of

anthracite for a total media depth of 30 inches. A recently implemented filter backwash routine

is summarized in Table 7. During the air scour event, even distribution of the air flow was

observed across both halves of filter 18, and during the high rate water wash, similar flow

distribution was observed across both filter cells.

TABLE 7. Filter 18 Backwash Description

Backwash Event Duration

Drain both filter cells to about 0.5 feet above media. ~ 45 min.

Air scour west cell. 5 min.

Combined air and water wash until water level reaches 1.8

feet.

High rate water only wash. 5 min.

ETSW at 66percent of pump speed. 8 min.

Air scour east cell. 5 min.

Combined air and water wash until water level reaches 1.8

feet.

High rate water only wash. 5 min.

ETSW at 66percent of pump speed. ~ 8 min.


Refill filters

Filter to waste (both cells together) - recently implemented

by water quality staff.

60 min.

Return to service.

During the high rate water wash, the filter media expansion was measured using a Secchi type

disk to detect the top of the expanded anthracite media. The measured expansion for the west

filter cell was 5 inches, and the measured expansion for the east cell was 4.5 inches. Based on a

total filter media depth of 30 inches, the bed expansion was approximately 17 percent for the

west cell and 15 percent for the east cell. To achieve good cleaning of the filter media during

backwash, a bed expansion of 20 percent or greater is typically recommended. The design

engineer for the filters commented during the study that the backwash pumping rate was

currently limited to 90 percent capacity due to a pump vibration problem. Once this issue is

resolved, slightly higher bed expansion should be achievable. This special study was only

conducted on both cells of Filter 18 during September water temperatures. Plant operators are

encouraged to complete this study on all the filters to establish baseline information, and

conducting this study on a routine basis is considered an essential component of a filter

maintenance program. Water temperatures in Pennsylvania change significantly throughout the

year, and these changes in temperatures directly impact water density, which in turn impacts bed

expansion. Other filter plants in Pennsylvania have documented that percent bed expansion

increases in winter and decreases in summer.

Special Study 2: Filter 18 Backwash Cleaning Efficiency

The efficiency of the backwash for cleaning a filter was assessed by collecting grab samples

from the wash water trough during backwash and measuring turbidity with a Hach portable

2100Q turbidimeter.


Photo of Initial Grab Samples from Filter 18 Backwash Troughs

The results of the grab sample analyses for Filter 18 are shown in the turbidity trend lines in

Figure 9. The trend lines for both filters are similar. At the beginning of the backwash the

turbidity of waste water exiting via the filter backwash trough was between 330 and 360 NTU.

At 5 minutes into the backwash, the high flow rate was reduced to achieve an extended terminal

sub fluidization wash (ETSW) rate where the media has minimal fluidization. During this time

of the backwash, the media level was checked, and minimal media fluidization was confirmed

with the bed expansion tool. At the transition from high wash to ETSW, the turbidity of the

waste wash water had decreased to between 5 and 6 NTU for both cells. The backwash

continued for approximately 10 minutes, which was slightly greater than the theoretical detention

time to replace the volume of water within and above the media. At the end of the backwash the

turbidity had been reduced to 0.7 NTU. The results of this study indicate that the filter was being

adequately cleaned, and the turbidity at the end of ETSW was within a range that would support

a short filter ripening period. Similar to the bed expansion study above, plant operators are

encouraged to complete this study on all the filters to establish baseline information. Conducting

this study on a routine basis provides useful information on the backwash efficiency and

condition of each individual filter and filter cell. It can also be used to evaluate the impacts of

seasonal variations in filter performance; which could ultimately provide operators with insights

that may be applied to shorten the filter ripening time.


FIGURE 10. Example Filter 18 Filter Flow Anomaly during Backwash Event

Special Study 3: Post Backwash Turbidity Recovery

The performance of filters following backwash is critical because a long filter ripening period

can result in the passage of pathogens (indicated by high turbidity levels) into the finished water.

Even relatively low levels of turbidity can result in large numbers of particles, such as

Cryptosporidium, passing through filters during this period. In addition, plants that are striving

to achieve the filter effluent turbidity optimization goal of 0.10 NTU often experience their

highest daily turbidity level during a filter ripening period. The Aspinwall plant has filter to

waste capability; however, use of this function was only implemented just prior to the time that

the CPE was conducted. In addition, the use of the ETSW as part of the filter backwash

procedure is also very effective for reducing filter ripening times. This practice was also

implemented just prior to the CPE.

The post backwash recovery performance for Filter 18 was recorded from the continuous filter

turbidimeter by the CPE team. This turbidimeter currently represents the performance of only

one of the two cells on filter 18. With the current sampling location, the monitoring does

accurately monitor performance during filter to waste. The post-backwash recovery performance

for Filter 18 is shown in Figure 11. For this backwash, the filter to waste period occurred for

about 55 minutes, and during this period the turbidity was relatively stable with values ranging

from 0.05 to 0.07 NTU. When the filter was returned to service, the turbidity was also stable as

indicated by turbidity values in the 0.06 to 0.07 NTU range. Results from this backwash indicate

that the combination of including the ETSW step at the end of filter backwash with filter to


combined effluent (i.e. both filter cells) was disconnected early due to the visual observation that

excessive sediment collected in the filter housing (see photo on page 35). The tap for this sample

was positioned at the bottom of the Filter 4 effluent pipe at a location which included flow from

both the west and east filter cells. Some of the sediment captured within the MPA filter and

housing appeared to be rust, while some appeared to be sand and anthracite. It is possible that

some of the filter media was present from the recent filter renovations, and media replacement.

However, if the presence of filter media within the filter effluent line were to persist, this would

be an indication of a potential underdrain integrity issue. Therefore, PWSA should visually

inspect the condition of each filter following backwash to insure depressions are not present

across the filter surface. The lab was not able to definitively identify the cause of the brown

discoloration of the cartridge; but, this type of discoloration is not typically present when

pretreatment processes are optimized.

To further evaluate performance of Filter 4, and determine the impact of sample location, another

MPA sample filter was connected to a different tap on the effluent line of the West half of Filter

4. The same brown color was noted, but to a lesser degree. Significantly less inorganic sediment

was noted as well. Visual observation of the MPA cartridge resulted in valuable discussion with

PWSA staff regarding the optimal sample tap location within the circumference of the filter

effluent pipe. In summary, Department staff encouraged PWSA to reference the turbidimeter

manufacturer sample tap location guidance. Everyone agreed that the bottom of the pipe should

not be used for future sample tap locations. Overall, the results of both Filter 4 effluent MPA’s

were rated “acceptable” by lab staff due to the determination that particulates were inorganic in

nature, and the fact that no cysts or oocysts were identified and the sample. Complete MPA

sample results are attached at the end of this CPE report.


Photo of Clear Well Effluent MPA Cartridge at Conclusion of Sampling

Special Study 5: Turbidity Data Integrity Assessment

A series of special studies were conducted to assess the integrity of the turbidity data being

collected from the individual filters and combined filter sample locations. This series of studies

focused on turbidimeter flows, turbidimeter operation and settings and the impact of these factors

on data quality. A summary of each study (5A through 5D) which contributed to the overall

assessment of turbidity data integrity follows:


Special Study 5A: Online Turbidimeter Flow Rate and Sample Detention Time Assessment

To assess the flow rate through the online Hach 1720E turbidimeters located at the IFE, CFE,

settled and clarified as well as the Surface Scatter-7 raw water turbidimeter, the CPE team used a

graduated cylinder and a stop watch to measure the flow rates from drain lines. The Filter 9

turbidimeter (2650 mL/min), Filter 16 turbidimeter (2800 mL/min), CFE north turbidimeter (880

mL/min), CFE south turbidimeter (1500 mL/min), raw Surface Scatter 7 turbidimeter (2800

mL/min), and clarified turbidimeter (1450 mL/min) exceeded the manufacturer’s recommended

flow rate range of 250 to 750 mL/minute, as shown in Figure 12. To obtain the most accurate

turbidity data, it is critical that the flow rate is consistently maintained as per the manufacturer’s

recommendations.

FIGURE 12. Turbidimeter Flow Rates vs. Manufacturer Specifications.

*Note that the recommended flow rate for the surface scatter 7 is between 1 L/min and 2 L/min

Additionally, the CPE team calculated the sample line detention time of the online Hach 1720E

turbidimeters on filters 16, Filter 9, CFE north, CFE south, settled, raw water (Surface Scatter 7)


and clarified. The length of piping from the sample ports to the influent ports of the on-line

turbidimeters were measured with a tape measure. Using the calculated sample pipe volume and

flow rates from the sample ports to the turbidimeters, a detention time was calculated for each

turbidimeter as listed Figure 13. The detention times varied between 0 (negligible) and 7.73

minutes. Detention times for Filter 9, Filter 16, and the Settled turbidimeters were one minute or

less allowing rapid responses to water quality changes. Raw, clarified, CFE north and CFE south

turbidimeter sample lines had greater than one minute sample line detention times. Overall filter

plant staff should always attempt to mount all online turbidimeters as close as possible to their

respective sampling location.

FIGURE 13. Turbidimeter Sample Detention Time Check.


Special Study 5B: Online Turbidimeter Settings Check

The CPE team checked the settings on the online Hach 1720E turbidimeter controllers, and the

findings are summarized in Table 8. An output span of 0-1 NTU for IFE and CFE turbidimeters

is not sufficient to determine regulatory compliance. The state of Pennsylvania Safe Drinking

Water Act Title 25 Chapter §109 requires that accurate filter water turbidity data be recorded and

reported. Additionally, specific actions are required in Ch. 109 whenever IFE turbidity exceeds

1 NTU or 2 NTU and when the CFE turbidity exceeds 1 NTU. Therefore, PWSA is required,

for regulatory IFE and CFE turbidity data, to establish a method to record actual turbidity spikes

regardless of their magnitude. According to raw and clarified turbidity data provided by PWSA,

raw turbidity appears to be capped at 100 NTU while clarified turbidity appears to be capped at

10 NTU, and settled turbidities appear to be capped at 5 NTU. Since process controls and

consultant studies may be based on raw and clarified water turbidities, it is also important to

accurately record the magnitude of turbidity spikes for raw, clarified, and settled water. Also,

differences between the turbidimeter output span settings and SCADA data should be

investigated to verify data integrity. Currently the 1720E turbidimeters are set to hold outputs

when communication is lost with the controller. The error hold mode Transfer Outputs setting

allows the operator to send a set value (0-20 NTU) which can be used as a tool to more clearly

identify when communication has been lost which may initiate manual verification and

investigation.

TABLE 8. Turbidimeter Settings

Turbidimeter Location

Raw, clarified, settled, CFE

north (even), CFE south (odd),

IFE 9 and IFE 16

Turbidimeter Model Raw-Surface Scatter 7

All others 1720 E

Controller Model and Data

Logging Setting (1)

SC-100 (clarified, CFE south,

IFE 16). All others SC 200

Time & date setting correct;

15 minutes

Signal Averaging (2) All at 30 seconds

Bubble Reject (3) On


Turbidimeter Location

Raw, clarified, settled, CFE

north (even), CFE south (odd),

IFE 9 and IFE 16

Output Span (4) Raw-0-10,000 NTU

Clarified-0 to 100 NTU

Settled- 0 to 5 NTU

CFE and IFE- 0-1 NTU

Error Hold Mode (5) All set to hold outputs

(1) Check to see if current date and time are correct. Check frequency of data logging. Default is 15

minutes for Hach models.

(2) Default for Hach models is 30 seconds. This is acceptable in most cases.

(3) Default is On for Hach models. This is acceptable in most cases.

(4) The output span should be set to record accurate data to SCADA.

Accessing output span for Hach SC200 controller: Menu/SC200 setup/Output setup (select 1 or 2;

select Source to see which turbidimeter is highlighted and then Back button)/Activation (low

value; high value).

(5) Specific to Hach 1720E and FilterTrak 660 models. Default is to hold outputs and send last known

value to SCADA when turbidimeter loses communication with controller. Better option is

Transfer Outputs (TO) to send an operator-selected value to SCADA (e.g., 0, 20) to make operator

aware of problem.

Special Study 5C: Online Turbidimeter Data Spike Investigations

As part of data integrity review, the CPE team reviewed IFE turbidity spikes using data from

September 2016 to September 2017 to document data integrity procedures used by plant staff.

Since the water system was using two different CFE meters to monitor composite IFEs from the

north (even) and south (odd) filter galleries, the team also investigated a turbidity spike which

was recorded on one CFE turbidimeter but not the other. Figure 14 shows the investigation of an

IFE turbidity spike and Figure 15 shows the comparison between the CFE meters.

Figure 14 shows an abrupt increase in the Filter 12’s IFE turbidity recorded by the SCADA

system on January 24, 2017. If turbidity is high, operators report the value they see on the

turbidimeter's controller (instead of the SCADA screen) and report it every 4 hours on the

monthly operational report (MOR). The first two MOR turbidity values recorded on January 24th

indicated a lower turbidity value measured at the meter than what the SCADA system was

recording. The next two MOR values from January 25th show the same turbidity value as the

SCADA recorded. There was a lack of available information to document this elevated turbidity


event so it remains unclear whether the turbidity values recorded during this period were a result

of a filter performance problem, data integrity issue, or combination of both. In either case,

additional follow-up to this event is warranted and to document any actions taken to address the

turbidity event.

FIGURE 14. Filter 12 IFE Turbidity Profile January 24-25th 2017

The CFE team graphed maximum daily CFE turbidity obtained from the north (even) and south

(odd) composite turbidimeters for the month of August 2017 and identified turbidity spikes.

Figure 15 shows north and south CFE turbidity every minute for August 31st when the turbidity

spiked. SCADA data recorded for the north CFE was higher than the south CFE on August 31st

for approximately one hour, however MOR data did not confirm a difference between north and


south CFE turbidity data. The MOR data indicated a difference between the turbidimeter

controller reading and data recorded by SCADA. When assessing plant performance relative to

meeting the turbidity optimization goals, the highest turbidity values that occur each day should

be recorded. These examples are provided to demonstrate how performance can be significantly

different based on how data is collected, graphed, and interpreted.

Special Study 5D: Online Turbidimeter Verification

A comparison study of the turbidity readings from a Hach 2100Q portable turbidimeter

(provided by the CPE team), the plant Hach TU 5200 benchtop turbidimeter, Surface Scatter 7

on the raw, and the Hach 1720E continuous turbidimeters on the clarified, settled, combined

(north and south), and Filter 9 and 16 effluents was conducted by taking grab samples from the

FIGURE 15. North and South CFE Turbidity Comparison August 31, 2017


drain lines of the continuous turbidimeters or other locations as available. Collecting samples

from the turbidimeter drain line is usually not recommended due to the potential for picking up

particles from the line but there was not a better sampling location for some of the meters. An

optimum grab sampling setup would include a sample tap (i.e., T or Y configuration) off the feed

line to the turbidimeter. Results of the comparative study for the raw, clarified, and settled

waters are summarized in Figure 16. Results of the comparative study for the north and south

CFEs, and Filter 9 and 16 turbidimeters are summarized in Figure 17. Readings from the

portable and benchtop turbidimeters are expected to be slightly higher than the continuous

instruments due to sample handling, use of a sample cell, and stray light potential related to the

portable and bench meters, but readings should be within 10 percent of the raw, clarified and

settled meters and +/- 0.05 NTU of the online IFE and CFE meters.

Figure 16 indicates, the raw water grab sample readings analyzed by the portable turbidimeters

were within acceptable ranges for those two portable turbidimeters, but outside the range when

compared to the on-line meter. The clarified water grab sample readings for all the meters were

within acceptable ranges. The settled water grab sample readings analyzed by the portable,

benchtop and on-line meters were outside the acceptable range but the grab sample location was

in the lab while the on-line meter sample tap location is at the settled water line upstream of the

filters which may indicate different water quality between the two locations.

Figure 17 indicates, the CFE and IFE grab sample readings analyzed by the benchtop and

portable turbidimeters from the north and south CFEs and filters 9 and 16 IFEs. All the values

from the grab samples were higher than the on-line instrument values. Values from the benchtop

and portable meters were outside the acceptable range for the South CFE and both IFE samples.

The IFE grab samples were not collected from the same tap as the on-line instruments which

may contribute to the disparity when comparing the values. The north CFE grab sample was

taken from a hose two feet from the turbidimeter; the IFE grab samples were taken at a tap

associated with the flow meter. Currently, the taps for the on-line IFE turbidimeters only

provide water from the west cell of the filters which may not be representative of the turbidity

from both the east and west filter cells combined. The grab sample tap location included both

cells but was from a tap associated with the filter flow meter.


PWSA currently conducts turbidity comparisons of their on-line turbidimeters with grab samples

obtained daily from the raw, settled, and both CFE locations and measured on the benchtop

meter. Both the on-line and benchtop turbidity values are recorded on a lab sheet. However,

there are no established percent difference (i.e. >15 percent) which would trigger additional

investigation if the values vary. PWSA staff are encouraged to assess their current IFE and CFE

grab sample locations and consider the benefits of establishing a more representative grab

sample location; more specifically, installation of a Y or T splitter just upstream of the

turbidimeter influent location would enable a grab sample representative of water entering the

turbidimeter. Conducting weekly verification of IFE and CFE turbidimeters helps to ensure that

sound data is being used to assess performance. But, it is necessary to first establish

representative sample taps and a repeatable comparison sampling SOP which includes specific

trigger points and follow up actions.

Figure 16. Raw, Settled, & Clarified Turbidity Comparison


operators do not account for the change in specific gravity and percent weight in their

calculations when they receive a new batch of chemical. This created a discrepancy of 1.7 mg/L

in the calculated dose on September 20th; the operator calculated dose was 32.3 mg/L, and the

CPE team calculated dose was 34 mg/L

Special Study 8: Coordinated Water Quality Grab Sampling

Several members of the CPE team worked together on a coordinated grab sample event.

Samples were collected between 11:20am and 12:00pm on September 20, 2017 in an attempt to

capture a “snapshot in time” of water quality at specific locations throughout the filter plant.

Following the flow of water through the filter plant, representative samples were collected from

raw water, recycle tank, rapid mix chamber, combined clarifier effluent, west sedimentation

basin, east sedimentation basin, north CFE, south CFE, and clear well effluent. Each sample

location was analyzed by the PA DEP Bureau of Laboratories (BOL) for multiple parameters.

Results are summarized in Table 11 and associated Figure 18. This data indicates that on

September 20, 2017, all parameters evaluated met applicable Safe Drinking Water standards at

the clear well outlet to the distribution system.

Table 11. Coordinated Water Quality Grab Sample Results

In Table 11, “UC” indicates Unregulated Contaminant; concentrations / values that were

reported with a "<" qualifier were assigned a "0" concertation. Fluoride and color were analyzed

but reported with "non-detections" and not included in this table. Please note that 39.6 mg/L

Raw Recycled Rapid Mix Combined Clarified West Sed Basin East Sed North CFE South CFE Clear Well Outlet MCL/MRDL

Alkalinity 49.6 37.8 40.2 37.2 37.2 37 36.8 36.4 68.2 UC mg/L

Aluminum 116 23.4 66.7 0 0 0 0 0 0 200 ug/L

Calcium 23.33 30.555 24.54 25.45 30.9 35.582 35.576 39.841 38.364 UC mg/L

Hardness 87 108 90 71 108 122 122 133 130 UC mg/L

Iron 0.233 1.681 9.171 1.506 0.36 0.157 0 0 0 0.30 mg/l

Bromide 70.53 0 69.48 69.46 77.25 76.5 0 0 0 UC ug/L

Magnesium Total 7.034 7.729 7.07 1.789 7.588 8.04 8.116 8.132 8.262 UC mg/L

Manganese Total 57 523 367 16 40 37 0 0 0 50 ug/l

pH Electronic 7.9 7.5 7.2 7.2 7.4 7.4 7.3 7.4 8.5 6.5 - 8.5

Sodium 16.03 18.94 23.36 5.381 16.9 18.242 19.561 21.328 39.643 UC mg/L

Temperature 18.68 18.62 18.55 18.53 18.48 18.42 18.32 18.22 18.15 UC

TDS 170 220 192 192 202 224 200 218 228 500 mg/l

Sulfate 48.74 56.9 49.65 49.21 55.43 56.15 56.19 56.3 59.01 250 mg/l


sodium was measured at the clear well outlet. In 2003 EPA published a document titled

Drinking Water Advisory: Consumer Acceptability Advice and Health Effects Analysis on

Sodium (EPA 822-R-03-006). The document provides guidance on concentrations at which

problems with taste would likely occur (30-60 mg/L). It also re-affirms a guidance level for

sodium in drinking water of 20 mg/L for those individuals restricted to a total sodium intake of

500 mg/day. Sodium is considered an unregulated contaminant; PWSA should consider further

evaluation of the sodium levels entering the distribution system and determine if a reduction in

sodium levels may be achieved as treatment processes are optimized.

Figure 18. Water Quality Grab Sample Graph

This type of special study can provide valuable data relative to the stability or instability of water

chemistry as it passes through each treatment process along with the associated removal

percentages. Figure 18 provides an overall summary; however, the true value of the special

study lies in more closely evaluating (adjusting graphical scale) each individual water quality


parameter at each unit process. For example, Figure 19 indicates a total manganese baseline raw

water concentration of 57 ug/L, followed by a peak of 523 ug/L within the recycle tank, 367

ug/L at the point of rapid mix, and significant reduction to 16ug/L at the combined clarifier

effluent. Figure 19 shows increases in total manganese through the sedimentation basin, with a

sedimentation basin effluent of approximately 40 ug/L. PWSA should also note that hardness,

calcium, bromide, total dissolved solids, sodium, sulfate, and magnesium also increased, to some

extent, in the settling basins. Additional monitoring should occur to further evaluate these

trends. Documentation of significant increases may indicate recontamination as a result of

surface run-off and/or solids leaching/resuspension. PWSA staff report that solids have not been

removed from the sedimentation basin for approximately 25 years. Zero total manganese was

detected in the north CFE, south CFE, and clear well outlet. In this example, the information can

be useful for assessing the effectiveness of potassium permanganate and chlorine oxidation of

manganese through the treatment processes as well as the impact of manganese recycle through

wash water return.

Figure 19. Total Manganese Trend


MAJOR UNIT PROCESS EVALUATION

Major unit processes were assessed with respect to their capability to meet the optimized settled

and filtered water goals as well as the disinfection goals based on CT (residual concentration

multiplied by contact time prior to the first customer). The capability of each individual unit

process was also assessed to verify its ability to provide consistent optimized performance. This

level of plant performance is considered necessary to help ensure removal or inactivation of

pathogens. Calculation of plant disinfection capability was based on chlorine CT values outlined

in the USEPA Guidance Manual4 for meeting both filtration and disinfection requirements.

Since the treatment processes of the plant must provide multiple effective barriers at all times, a

peak instantaneous operating flow was determined. The peak instantaneous operating flow

represents conditions when the treatment processes are the most vulnerable to the passage of

parasitic cysts and microorganisms. If the treatment processes are adequate at the peak

instantaneous flow, then the major unit processes should be capable of providing the necessary

effective barriers at lower flow rates.

The maximum operating flow rate of 62,500 gpm (90 MGD) was selected by the CPE team as

the peak instantaneous operating flow rate. The peak instantaneous flow corresponds to the

maximum number of pumps that would operate at any given time. The plant achieves various

flow rates by operating various combinations of pumps at various stations. During winter

months, flow rates have approached 62,500 gpm when multiple line breaks occurred in the

distribution system.

Unit process capability was assessed using a performance potential graph, where the projected

treatment capability of each major unit process was compared against the peak instantaneous

operating flow rate. The Major Unit Process Evaluation graph developed for the PWSA

Aspinwall WTP is shown in Figure 20.

4 Guidance Manual for Compliance with the Filtration and Disinfection Requirements for Public Water Systems

Using Surface Water Sources, USEPA, Office of Drinking Water, Washington, D.C. (1989), revised 1991.


Figure 20. Major Unit Process Evaluation Graph

11/3/2017 - 53 - Final PWSA CPE Report.docx

The unit processes evaluated during the CPE are shown along the vertical axis. The horizon-

tal bars on the graph represent the projected peak capability of each unit process that would

support achievement of optimized process performance. These capabilities were projected

based on several factors including the combination of treatment processes at the plant, the

CPE team’s experience with other similar processes, raw water quality, industry guidelines,

the PWSA Aspinwall WTP design, and regulatory standards.

Each unit process can fall into one of three categories:

Type 1: Where the bar for the unit process exceeds the peak instantaneous flow (> 100

percent of peak flow), the plant should be expected to achieve the performance

goals.

Type 2: If the bar for the unit process falls short but close to the peak instantaneous flow

(80 to 100 percent of peak flow), then operational adjustments may still allow

the plant to achieve the performance goals.

Type 3: If the bar for a particular unit process falls far short of the peak instantaneous

flow (< 80 percent of peak flow), then it may not be possible to achieve the per-

formance goals with the existing unit process.

The shortest bar represents the most limiting unit process relative to achieving optimized plant

performance. The major unit processes evaluated included flocculation, clarification,

sedimentation, filtration, and disinfection.

Flocculation and clarification is achieved with four flocculation and clarification basins,

operated in parallel. Each basin includes two, 2-stage flocculators and a conventional

sedimentation basin. The flocculators are operated at constant speed. Basin #3 had been out

of service for several months, so two flocculators and one clarifier were not considered in the

major unit process evaluation. A third flocculator was also not operating at the time of the

CPE, but it was assumed to be functional in the major unit process evaluation because it

would typically be running under normal conditions.

Based upon the flocculation unit design (i.e., a minimum water temperature ≤ 5 °C and

multiple stage mixing), a hydraulic detention time (HDT) of 20 minutes was selected to rate


the process. The combined flocculation basin volume was approximately 1,157,635 gallons

(not including two of the eight flocculation units since Basin #3 was out of service). The

resulting rating of the flocculation process was 83.3 MGD (Vol/HDT x 1440/106). This was

less than the peak instantaneous flow rate of 90 MGD and identifies the flocculation process

as a Type 2 process.

The total surface area of three of the four conventional clarifiers was 29,160 ft2 with an

average water depth greater than 14 feet. The CPE team assigned a surface overflow rating of

0.7 gpm/ft2. Based on this information, the total rated capability for the clarification unit

process was 29.4 MGD. This was considerably less than the peak instantaneous flow rate and

results in categorizing clarification as a Type 3 process.

Settled water from the clarifiers was gravity fed into a central receiving basin and distributed

into the east and west sedimentation basins, operating in parallel. The total surface area for

both basins was 1,000,000 ft2. Water flowed approximately 1,400 feet across each basin into

an effluent conduit surrounded by mud walls, located on the bottom of the basin at the other

end. The CPE assigned a surface overflow rate of 0.5 gpm/ft2 to each basin because the

effluent orifice was located at the bottom of the basin. Based on this information, the total

rated capability for the sedimentation process was 720 MGD. This was considerably greater

than the peak instantaneous flow rate, which identifies sedimentation as a Type 1 process.

Filtration was performed using eighteen dual-media, rapid rate filters each containing two

cells. The dimensions of each cell were 57 by 18 feet, or 1,140 ft2 each. With one filter out

of service, the surface area of seventeen filters was 38,760 ft2. The PA DEP permitted a

hydraulic loading rate of 2 gpm/ft2 for the Aspinwall filters, which was used in the evaluation.

Based on this information, total rated capacity of the filtration process was 111.6 MGD. The

filtration process rating was above the reported peak instantaneous flow and the filters are

therefore rated a Type 1 process.

The disinfection process was assessed based on the PA DEP requirements for inactivation of

1- log (90 percent) of Giardia cysts and 4 log (99.99 percent) of viruses (in addition to

adequate turbidity removal via pretreatment and filtration). For disinfection with chlorine, the

Giardia inactivation requirement is more stringent than the virus disinfection requirement. As


such, Giardia inactivation was used as the basis for the chlorine disinfection evaluation. The

point of chlorine addition at the PWSA Aspinwall plant was in the combined filter effluent

line at the filter pipe gallery, so the only contact time for the chlorine is in the clear well. The

residual disinfectant concentration (C), in mg/L, multiplied by the effective time the water is

in contact with the disinfectant (T), in minutes, comprises CT.

For disinfection in the clear well, a required CT value of 85.5 mg/L-min was obtained from

the USEPA Guidance Manual3 using a chlorine residual of 0.6 mg/L, a maximum pH of 8.5,

and a worst-case temperature of 5 °C. These criteria were selected based on a review of

historical data at the clear well effluent. Although chlorine residuals of less than 0.6 mg/L

were observed on many of the days reviewed by the CPE team, PWSA staff were using a

higher baffling factor prior to April 2017. Using the PA DEP established baffling factor of

0.3 means that chlorine residual level will need to be maintained at a higher level than in the

past to maintain the required inactivation ratio.

The total volume of the clear well was calculated at 31,265,000 gallons assuming a minimum

water level of 13.5 feet. The volume calculation accounted for the reduction in volume due to

structural columns within the clear well. Based on this information, the total rated capacity of

the disinfection process was 91.5 MGD, which was slightly greater than the peak

instantaneous flow rate. As a result, disinfection is considered a Type 1 process

The major unit process evaluation shows that the Aspinwall plant’s major unit processes

should not limit the ability of plant operators to achieve turbidity and disinfection

optimization goals under current flow conditions. The flocculation process is rated Type 2;

however, routine preventative maintenance combined with good operational practices and

application of optimization skills could help to offset this rating. The clarification process is

rated Type 3, but this process is followed by the sedimentation process which is rated Type 1.

The combined use of both settling processes, routine preventative maintenance of these units,

and application of good operational skills will be critical to consistently achieving settled

water optimization goals and protecting the newly renovated filters.


PERFORMANCE-LIMITING FACTORS

The areas of design, operation, maintenance, and administration were evaluated to identify

factors that limit performance. These evaluations, and the resultant list of what appeared to be

performance limiting factors, were based on information obtained from the plant tour,

interviews, performance and design assessments, special studies, and the best professional

judgment of the CPE team. Each of the factors was assessed for a possible classification as A,

B, or C according to the following guidelines:

A Major effect on a long term repetitive basis

B Moderate effect on a routine basis, or major effect on a periodic basis

C Minor effect

After lengthy discussion by the CPE team, the performance-limiting factors identified were

prioritized as to their relative impact on performance, and they are summarized in Table 12

below. While developing the list of factors limiting performance, over 50 potential factors

were reviewed, and their impact on the performance of the Aspinwall WTP was assessed to

the best of the team’s ability using available information. Each of the factors along with

specific examples of why the factor was identified are described in this section.


TABLE 12. Summary of Performance Limiting Factors

Rank Rating Performance Limiting Factor Category

1 A Policies Administrative

2 A Supervision Administrative

3 A Representative Sampling Operations

4 A Application of Concepts and Testing to Process Control Operations

5 A Maintenance Preventative/Corrective Maintenance

6 A Planning Administrative

7 A Complacency Administrative

8 A Reliability Administrative

9 B Disinfection Design

10 B Compensation Administrative

11 B Reserves Administrative

12 B Chemical Storage and Feed Facilities Design

13 B Clarification/Sedimentation Design

14 B Process Controllability and Instrumentation/Automation Design

15 C Operational Guidelines Operations

16 C Work Environment Administrative

17 C Intake Structure Design


Policies – Administration (A)

Existing policies or the lack of policies appear to hinder staff members from making all

necessary operational, maintenance, and management decisions to support optimized plant

performance. Examples of this performance limiting factor include:

• It does not appear that a clear policy to meet a full range of water quality optimization

goals has been established and communicated to staff at all levels.

• Vacancies in key management positions are affecting workloads, impacting stability

and communication within the organization. This leads to uncertainty which hinders

the ability of plant personnel to set priorities necessary to achieve and maintain

optimal water quality. Reference the organizational chart in Attachment 1.

• The existing policy requiring residency within the Pittsburgh city limits for all PWSA

employees limits the pool of available candidates, and sometimes results in highly

qualified candidates declining job offers. Ultimately, some positions remain vacant

because of the residency requirement.

• The policy that only lab staff can establish process control setpoints (e.g. ferric

chloride dosage) has diminished the role that properly certified operators can and

should play in maintaining optimal water quality. Lab staff are currently relied upon

for process control oversight, but a previous policy has reduced lab staffing from ten

to four.

• Operator certification does not appear to be adequately incentivized for existing staff,

or required for new hires.


Supervision – Administration (A)

This factor refers to management styles, organizational capabilities, or communication

practices at any management level which appear to adversely impact the plant

performance. Examples of this performance limiting factor include:

• The Director of Water Production position is vacant. An optimization champion (i.e.

someone who understands safe drinking water requirements and can establish

optimized performance goals) is needed for this position. This vacancy has also

resulted in a lack of clearly defined roles and responsibilities which impacts

completion of specific tasks required to support optimal performance. Reference the

organizational chart in Attachment 1

• Simultaneous compliance does not appear to be a priority; the primary focus is THM

precursor removal and DBP control, with limited focus directed towards turbidity

optimization of each unit process

• Operators are not involved with water quality process control decisions, which limits

their review and ownership of turbidity and disinfectant residual compliance data.

Improperly certified operators routinely make process control decisions relative to

water quantity.

• Compartmentalization of duties within the organization has impacted the overall

ability to make efficient and timely decisions. Roles and responsibilities are not

clearly defined, leading to uncertainty regarding who has primary responsibility for

completion of certain tasks.

• There is a reliance on consultant recommendations with limited input or involvement

from plant staff to develop process control related special studies in the plant.

Communication practices are not ensuring plant staff awareness or actively soliciting

their input for prioritizing and developing consultant’s studies or specific projects.

• An in-house training program has not been established but is desired by operational

staff.


Representative Sampling – Operations (A)

Accurately assessing plant performance requires sampling and instrument settings that can

capture process performance. Some examples of representative sampling issues that were

identified during the CPE include:

• A method to assess turbidity spikes and understand when individual filters are online

(vs. offline) has not been established, which compromises associated turbidity data

integrity.

• Verification of massive amounts of critical water quality/compliance data by only one

individual reduces responsibility of shift operators to routinely vet turbidity/chlorine

data in a timely manner.

• Current IFE online turbidimeter sample tap location does not monitor both sides of

each individual filter, compromising critical regulatory and process control data.

• IFE flow records for some filters indicate up to approximately 1872 gpm of flow

during periods when those filters should be offline for backwash. This appears to

indicate an unresolved problem with the flow meter calibration and/or electrical

“noise” and/or valves not fully closing.

• Grab sample taps for individual filters are not representative of water quality from

each filter cell and filter to waste turbidity.

• IFE and CFE turbidimeters were capped at 1 NTU limiting the ability to assess

magnitude of turbidity spikes for process control and regulatory compliance.

• Filter to waste step was not consistently utilized prior to the CPE.

• Flow rates for turbidimeters evaluated by the CPE team were not within the

manufacturer recommended range (i.e. significantly higher).

• Constant head levels for the CL-17 chlorine analyzer evaluated by the CPE team were

not within the manufacturer-recommended range.


• Clarifier and sedimentation basin turbidity data provided was capped at a maximum

10 NTU and 5 NTU respectively.

• Individual clarifiers and individual sedimentation basin effluent turbidities are not

monitored.

• The continuous online raw water turbidimeter is not representative of Allegheny river

turbidity because it draws a sample after the point of potassium permanganate

injection.

Application of Concepts and Testing to Process Control – Operations (A)

Process control by plant staff is a key activity required to consistently achieve compliance

requirements and optimization goals. Examples of useful process control activities that

are not being completed and operational practices that do not support good process control

include:

• Ferric chloride dosage rates are rarely adjusted due to the perception that the

Allegheny river is a stable source, and the perception that the practice of enhanced

coagulation does not require close control of the coagulant dose.

• Process control tools, such as jar testing, streaming current monitor or zeta potential,

are not utilized to optimize coagulant and polymer doses; historical ferric chloride

dosage data are not routinely utilized to guide current dosing strategies.

• Giardia inactivation ratios reported by PWSA for the Aspinwall WTP were

consistently higher than those calculated by the CPE team. PWSA’s method of

determining minimum chlorine residual and minimum clear well volume data for use

in the CT calculation did not appear to be accurate.

• Operators do not have access to an accurate method to verify actual verses theoretical

ferric chloride dosages. During a special study, CPE team members calculated a dose

of 18.1 mg/L using the coagulant feed pump calibration cylinder; in comparison,

operators calculated a ferric dosage of 32 mg/L using SCADA data. Operators believe


this calibration cylinder is inaccurate due to the plumbing configuration; but, this

theory needs to be evaluated further.

• Operators do not have access to accurate plant flow rate data to calculate ferric

chloride dosages via SCADA.

• Neither clarifier sludge depth nor sludge density are tested; this type of testing could

potentially enhance performance and reduce clarifier breakdowns / maintenance. The

impact of elevated ferric chloride dose on sludge production and clarifier maintenance

has not yet been assessed.

• Clarification followed by sedimentation has resulted in a false sense of security;

clarified and settled water spikes are not investigated to optimize multiple barrier

performance.

• Routine secondary verifications of the individual filter turbidimeters are not conducted

(although turbidimeters are calibrated quarterly via a primary standard).

• Turbidimeter comparisons are conducted, but the data are not utilized to assess

accuracy of the on-line meters.

• An SOP has not been established to test new filter media (AWWA B-100 analysis) to

establish baseline condition and/or monitor change in condition with age.

• Long-term analysis of water quality data trends is not occurring in-house or routinely,

resulting in limited data-based decision making

• Plant staff are not involved in the design of, or conducting, special studies (e.g.,

optimizing permanganate feed locations, individual clarifier basin performance study,

filter backwash evaluation, in-plant DBP formation)

• Staff appear to accept preliminary process control modification recommendations

from consultants without thorough consideration of unintended process control

impacts (e.g. considering stopping raw water potassium permanganate feed and


relying on Mn removal via filtration process). Some recommendations may be based

on plant data that is not representative, due to previously listed data quality concerns.

• The impacts of filter backwash recycle on pretreatment processes or finished water

quality have not been studied. See recycle tank manganese residual (Figure 19)

• Staff were uncertain if east and west raw water intake structures allowed flexibility to

draw water from different depths within the river to target the best available source

water quality. Therefore, this is not a process control consideration.

Maintenance (Preventative/Corrective) – Maintenance (A)

Overall, the frequency and pace of emergencies has resulted in operations and

maintenance staff that are constantly in triage mode, with little to no time to conduct

proactive preventative maintenance. Examples of specific maintenance concerns are

listed below:

• Clear well maintenance and cleaning has not been performed and could lead to water

quality issues or failure.

• Lack of routine removal of sludge from flocculators and clarifiers appears to be

contributing to routine breakdowns. Apparent lack of maintenance resources results in

one of four clarifiers remaining offline for extended periods of time.

• Accumulation of sludge in the sedimentation basins reduces basin volume, likely

contributing to intermittent settled turbidity spikes, increase in some secondary

contaminants as listed in Table 11, and the presence of debris within the filters which

may ultimately result in filter short-circuiting.

• Line clogging (e.g., hypochlorite, soda ash) requires frequent maintenance and/or the

utility to bring chemicals close to the injection point.


• The plant flow meters are not calibrated and data are not accurately transmitted to the

SCADA system, making it difficult to accurately calculate and control chemical feed

rates or perform water accounting.

• Sedimentation basin effluent weir, location, condition and maintenance history appear

to be unknown to utility staff.

• The raw water intake valves do not appear to be adjustable (i.e., stuck in their current

percent open position), limiting flexibility to adjust water contributions from both East

and West intakes.

• Lack of a comprehensive work order system limits the ability to accurately track all

equipment in need of repair.

Planning – Administration (A)

The lack of long-range planning by a utility can have negative impacts on the future

operations and performance of a WTP. Current performance problems at the Aspinwall

WTP have been caused in part by a lack of planning in the past. The following examples

were identified during the CPE:

• A lack of prior long-range planning to build and maintain a sustainable water system

infrastructure has impacted plant performance. Current management has developed a

long-range plan to begin addressing this factor, but it has not yet been fully

implemented.

• A lack of prior planning to generate income sufficient to sustain a WTP capable of

achieving optimal performance goals has impacted performance of the Aspinwall

plant. Current management has developed a plan to address this issue but it has not

yet been fully implemented.


Complacency – Administration (A)

The design of the Aspinwall WTP provides ample capacity to meet the existing demand

flow which contributes to a sense of complacency within the water utility. Some

examples that were identified during the CPE include:

• Staff do not adjust coagulant dosage and clarifiers are not optimized for particle

removal, due to a reliance on the sedimentation basins and a perceived “stable” source.

The perception that the sedimentation ponds will be able to effectively remove

pathogens from all types of incoming water quality challenges has also allowed for the

process control emphasis to be placed almost exclusively on DBP and TOC control.

• PWSA has not adequately reinvested in its aging infrastructure, which has resulted in

breakdowns that impact water quality and redirect operator time and attention.

• Some infrastructure breakdowns have gone unaddressed for extended periods of time.

Maintenance staff cannot keep up with all needed repairs, and limitations force them

to deal with the “emergency of the week,” while other important repairs are on hold

for extended periods of time.

Reliability – Administration (A)

Inadequate facilities, equipment and the depth of staff capability present potential weak

links within the water utility to achieve and sustain optimized performance. Some

examples of this factor that were identified during the CPE include:

• The existing clear-well lacks redundant components and cannot be taken out of service

for maintenance. The ability to apply adequate disinfection is at risk if there is failure

of the current clear-well configuration.

• Redacted-Security Issue


• Some unit processes are not operating, with no identifiable schedule to be placed back

in service. In addition, some equipment and instrumentation is not providing reliable

information needed for optimal particulate removal:

▪ Three flocculators are out of service.

▪ One clarification basin is not operational.

▪ Raw water flow readings are inaccurate.

▪ IFE turbidity data is not reliably reflecting individual filter performance.

• The overall depth of staff capability is not sufficient to consistently and reliably meet

optimization goals. For example, maintenance staffing levels are insufficient to ensure

that current unit processes are operational. The laboratory is also understaffed and

there is a lack of certified operators to support optimal performance of a WTP of this

size. Compartmentalization of staff duties also limits the depth of staff capability and

the engineering department, along with other staff departments are dependent on

outside consultants.

Disinfection Barrier – Design (B)

• Due to the age of the clear well, structural issues with the potential to compromise the

disinfection barrier are developing; significant rehabilitation or replacement of the

clear well will be necessary to maintain the integrity of the disinfection process. The

lack of redundancy for the clear well does not currently allow it to be taken out of

service for maintenance, repair, or replacement. The clear well inlet and outlet wet

wells share a common wall and are covered by improperly sealed hatches that could

potentially allow the introduction of contaminants such as dust, debris, insects, etc.

Due to hydraulic limitations, the clear well water level cannot be lowered below 7.5

feet.


Compensation – Administration (B)

The current compensation structure appears to hinder PWSA’s ability to retain or develop

staff with the necessary qualifications and abilities to pursue optimized WTP

performance. Some examples of this factor that were identified during the CPE include:

• It has been difficult to compete with surrounding utilities for the best available staff,

therefore hindering the ability of PWSA to hire highly qualified individuals with skill

sets necessary to optimize performance. This has also impeded the ability to manage

the water system without relying on outside consultants.

• Historically, minimal incentives for operators to pursue certification appears to have

contributed to the current lack of depth in staff capability. For example, a lack of

compensation to attend training did not promote the importance of training and

certification. Not until recently have staff been allowed overtime to attend training and

this has not yet been fully realized by staff.

Reserves – Administration (B)

It appears that PWSA financial reserves have not been maintained to adequately cover

unexpected expenses or fund needed facility replacement costs. Some potential examples

of this factor that were identified during the CPE include:

• Revenues have been impacted by water accountability inaccuracies that have affected

collections (e.g. plant and customer meters and billing software). High (>50percent)

unaccounted for water also significantly reduces revenue.

• Reserves for capital replacement have not been adequately developed and do not

currently cover needs, resulting in emergency breakdowns that have affected

performance.

• Policies to use PWSA revenue for other city priorities, not necessarily benefiting the

water system, appear to have contributed to a lack of reserves, including:


• Providing free water for certain city needs.

• Contributing funding for city projects outside PWSA.

• The terms of the ALCOSAN contract requires PWSA to perform revenue

collection and payment to ALCOSAN for sewer accounts. PWSA must

compensate ALCOSAN regardless of whether the customer pays water or sewer

charges to PWSA.

• The terms of the PWSA lease agreement requires payment of $130M (water) and

$100M (sewer) to the city of Pittsburgh.

• A long-standing policy to subsidize Pittsburgh customers receiving water from

Pennsylvania American Water Company (PAWC) reportedly costs PWSA $5M

annually, which is paid to PAWC. This amount makes up the difference between

what PAWC charges its customers as compared to the PWSA water rates.

• The debt at the time of the CPE, in the amount of $750M, results in $0.40 of each

revenue $1.00 directed toward paying debt. This reduces the revenues available for

reserves.

Chemical Storage and Feed Facilities – Design (B)

• Chemical storage space for ferric chloride is limited, resulting in the need for frequent

(daily or twice weekly) deliveries. The plant has had to reduce the coagulant dose at

certain times to get by until the next delivery. Due to lack of storage, railcars sit full

of chemicals with no secondary containment.

• The current condition of sodium hypochlorite piping facilities requires the utility to

truck chemical to the filter effluent injection point.


Clarification/Sedimentation – Design (B)

• The clarifier capacity is inadequate, resulting in high surface loading rate and floc

carryover.

•

Process Controllability and Instrumentation/Automation – Design (B)

• Chemical feed rates must be changed manually and do not automatically adjust to

account for changes in plant flow rate, e.g., the chemical feed pumps are not flow-

paced. Raw water pumping flow requires a manual change. This lack of

automation/controllability requires a dedicated operator to staff the chemical feed

building and a dedicated engineer to staff the Ross Pump Station around the clock.

•

Operational Guidelines/ Procedures – Operations (C)

• Standard operating procedures (SOPs), or operational guidelines, are developed for

certain plant activities; however, they are not posted at critical locations (where they

would be utilized/quickly referenced) within the plant. Additionally, SOPs have not

been established to adjust pretreatment to accommodate for seasonal temperature

changes (e.g. floc speeds and associated mixing energy relative to water density).




Work Environment – Administration (C)

Overall work environment has impacted plant performance by impeding routine activities

needed to support process control decisions. Some examples of this factor that were

identified during the CPE include:

• Electrical, and other safety issues at the plant, have resulted in a dangerous work

environment and necessitated extra resources for emergency repairs and to address this

overall issue.

• The filter decks do not have hand rails which could present a safety hazard when

operators try to observe a backwash or conduct special studies such as bed expansion

measurements.

Intake Structure – Design (C)

•

• The east and west intakes are located very close to one another, which provides

limited resiliency. There does not appear to be functional capability to feed potassium

permanganate at the west intake, potentially limiting contact time for oxidation.


RESULTS OF THE COMPREHENSIVE...

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