Winnipeg Discoloured Water report, Jan. 30, 2014

8/13/2019 Winnipeg Discoloured Water report, Jan. 30, 2014

1/26

Summary port

Winnipeg Discoloured WaterInvestigation

Prepared forCity of WinnipegDecember 2 13

CH2MHILL3 Kenaston Boulevard

Winnipeg MB R P P


2/26

H M HILLCH2IYIHILL

CA204 488-2214204 488-2245

December 20, 2013461072/WBG 121813102642T0RTim Shanks, M.Eng, P.EngWater Distribution EngineerWater Services Division, Water Waste Dept.552 Plinguet AveWinnipeg, MBR2J OG1Subject: DiscolouredWater InvestigationDear Mr. Shanks,Attached please find our report that presents the findings-to-date from the investigations into theoccurrence and causes of discolouored water in the City of Winnipegs water system and to makerecommendations for the control and mitigation discoloured water.The findings of this study were determined using a combination of field investigations, waterquality sampling, bench-scale studies, and demonstration testing. The cooperation and inputprovided by City staff were critical to the preparation of this report.Sincerely,CH2M LL Canada Limited

Paul Wobma, P .Eng . MB)Project Manager

Quirien Muylwyk, P.Eng. ON)Regional Technology Manager Canada


3/26

Contents1 Introduction and Problem Statement 1 12 Safety of the Water Supply 2 13 Causes of Discoloured Water in the Citys Distribution System 3 14 Source of Causative Compounds Where did it come from? 45 Investigative Work to Confirm the Source How do we know? 5 16 Controlling and Preventing Discoloured Water 6 17 Reducing the Compounds Responsible for Discoloured Water from the Distribution

System What do we need to do? 7 18 Recommendations and Actions 89 Estimated Time to See Improvement How long will it take? 910 Measuring Success 10 1

TablesTable 1: Summary of Iron and Manganese in the Citys Water System 3 5Table 2: Summary of Recommendations and Actions with Schedule and Cost Implications 8 2

FiguresFigure 1: Monthly Discoloured Water Service Requests 1 2Figure 2: Geographical Distribution of Service Requests for Discoloured Water 1 3Figure 3: Water Quality Coinciding with Service Requests for Discoloured Water, Histogram of Iron

Concentrations 3 2Figure 4: Water Quality Coinciding with Service Requests for Discoloured Water, Histogram of

Manganese Concentrations 3 2Figure 5: Total Iron in Routine Distribution System Samples 3 4Figure 6: Total Manganese in Routine Distribution System Samples 3 4

4G1072_W8G121813102642T0R COPYRIGHT Z013 BY CH2M HILL CANADA LIMITED ALL RIGHTS RESERVED COMPANY CONFIDENTIAL


4/26


5/26


6/26

SECTION INTRODUCTION AND PROBLEM STATEMENT

Figure 2: Geographical Distribution of Service Requests for Discoloured Water

W4 TER N WASTE DEPAR TMENTMAP LEGEND WATER SER VICES DIVISION Discoloured Water Service Requests CREATED: ec 5 2 13 SCALE: 1:15

Discoloured Water Service Requests\Vinnipeg for Jan 1 2 13 to Oct 31 2 13

Wy

461 72_WBG1218131 2642T R COPYRIGHT l BY CH2M HILL CANADA LIMITED ALL RIGHTS RESERVE COMPANY CONFIDENTIAL 3


7/26

SECTION afety the ater upplyYes the water is safe. The Citys drinking water quality meets all provincial requirements andfederal guidelines for microbiological, physical and chemical parameters. The Guidelines forCanadian Drinking Water Quality identify a non-health based Aesthetic Objective for manganese at0.05 mg/L and this has been exceeded in some treated water and distribution system samples.Elevated levels above the aesthetic objective for colour-causing compounds both iron andmanganese have been measured in samples from the customer tap.While many consumers assume that discoloured water is not safe to drink, elevated iron andmanganese are not health concerns at the levels observed. This position was affirmed in thefollowing statement by Dr. Lisa Richards, Medical Officer of Health of the Winnipeg Regional HealthAuthority:

In my role as Medical Officer of Health for the Winnipeg Health Region work closely withthe Office of Drinking Water and the City of Winnipeg to review the situation with brownwater on a regular basis. We have reviewed the results of tests done on the brown water todate. Various components of the water were tested, including bacteria and otherparameters. Laboratory results to date for samples submitted by the City of Winnipeg do notindicate the water is unsafe to drink.We agree with the City of Winnipegs recommendation that residents should not drink thediscolouredwater or use it for purposes such as preparing food, but there is no indication atthis time that drinking the water would pose a health risk.The recommendation is precautionary in the event that new information comes to light thatmay change our risk assessment. We are monitoring the situation, and assessing any newevidence when it comes available.

Communications have been maintained with the Provinces Office of Drinking Water and the localhealth authorities to share water quality results and review activities undertaken by the City toinvestigate, control, and prevent discoloured water in the Citys drinking water system.

461072_W6G121813102642T0R 2 1OPYRIGHT 2013 BY CH2M HILL CANADA LIMITED ALL RIGHTS RESERVED COMPANY CONFIDENTIAL


8/26

SECTION 3auses o iscoloured Water the itysis tri ution SystemIn this section, the data reviewed to identify the cause of the discoloured water is discussed,starting with samples collected at the customers tap, and working backwards in the system: tapsamples, water main samples also referred to as distribution system samples , treated water fromthe plant WTP , and the source water for the WTP. This is done to assess where in the water cyclethe compounds causing discoloured water are present to help determine how to control andprevent discoloured water occurrences.Sampling at the Customers Taps: In response to discoloured water service requests, the City wasable to collect water quality information at several customer locations for a wide range of waterquality parameters including metals, bacteriological quality, disinfectant residuals, turbidity andcolour. Four years of data were collected and results for the bacteriological quality and disinfectantresiduals were good in these samples. For samples with higher levels of turbidity and colour, thesedata reveal that iron and/or manganese were measured at concentrations high enough to bedetected by the customer as discoloured water see Figure 3, Water Quality Coinciding with ServiceRequests for Discoloured Water, Histogram of Iron Concentrations and see Figure 4, Water QualityCoinciding with Service Requests for Discoloured Water, Histogram of Manganese Concentrations .Also of note is a trend of decreasing iron and increasing manganese levels in the more recentcustomer samples collected in response to service requests. Although manganese may bedominating the discoloured water occurrences, iron is also an important contributing factor.

4SlO72_WBGI18l3lO2642TOR 3-1COPYRIGHT 2 3 BY CH2M HILL CANADA LIMITED ALL RIGHTS RESERVED COMPANY CONFIDENTIAL


9/26

WINNIPEG DISCOLOURED WATER INVESTIGATION

Figure 3: Water Quality Coinciding with Service Requests for Discoloured Water Histogram of Iron Concentrations

Figure 4: Water Quality Coinciding with Service Requests for DiscolouredWater Histogram of ManganeseConcentrations

Iron in Discoloured Water Samples samples in cold water apparent colour> 1 5 TCU

35

30

25CC20

U0

156z

10

00 015

0.15-0.3 03 0 45 045 06Concentration Range for Total Iron mgIL

higher

Manganese in DiscolouredWater Samples samples in cold water apparent colour> 15 TCU

35

30

25EnC

20

6z

10

5

0

Aesthetic Obiective for Manoanes = fl.05 malL

3 2 COPYRIGHT 2013 BY CH2M HILL CANADA L IM IT ED A LL RIGHTS RESERVED COMPANY CONFIDENTIAL 461072_WBG121813102642T0R


10/26


11/26

-E

nC1>oU>UCoCCoxI.a>

-Eaa0

C[ON

CimCCL

[A1mr

[u[AONdS

[ml[Emu

OA

O[dCS

on.

ov

OUAc

o

.5

6AON

6dCS

6OC

6OAV

6OL

6UC

9AON

9dCS

on

9L

9UC

LA

Ld

Lm

LAV

LLu

9CN

9d

-S

EC

C.2E.0U

>CCCU0D0Cmam

Ua0E3EUC0.04UaC.40C40IU.aU

a030CFz0>zCa0>aDiaUaI3aC0FC0CzCCz:a0ra:a0

C0EUCC0-S

zU>

Ua0ELE4U>3C-D4UaC4z0UaC050CUC40I0a5U-SaC

0

0

0

0

0

0

1

3

d

o

o

6wo

0

Sa>Caa

C

C

0

0

C

N

C

a

0

C

0

o

a

0

0

0

6woe

W

o

0

C

C

0

q

o

o


12/26


13/26


Table 1: Summary of Iron and Manganese in the Citys Water SystemLocation within the Water Iron ManganeseSystemTreated Water from the Water Historically low levels Variable, general trend ofPlant increasing levels with timeLess than raw water levels

Iron is effectively controlled Higher than raw water levelswithin the water plant The source of manganese is

the treatment choice ofcoagulant within the plant,and to a lesser degree, theraw waterNot all of the manganese inraw water or that added fromcoagulant use is removedwithin the WTP

Raw Water Deacon Reservoir Low levels of iron Low levels of manganese, witha gradual increase observedContinue monitoringmanganese in the DeaconReservoir

Intake Shoal Lake Low levels of iron Low levels of manganese, withseasonal peaks and a gradualincrease observedContinue monitoringmanganese in Shoal Lake

3-6 461072_WBGIZIB131O2G42TORCOPYRIGHT 2 3 BY CH2M HILL CANADA LIMITED ALL RIGHTS RESERVED COMPANY CONFIDENTIAL


14/26


15/26


16/26

SECTION 4SOURCE OF CAUSATIVE OMPOUNOS WHERE OlD IT COME FROM?

Summary: The data from the WTP distribution system and customers taps suggest that the sourceand fate of manganese through the WTP is key to the occurrence of manganese in the distributionsystem and the complaints of discoloured water. Eliminating the source of manganese and flushingthe manganese particles from the distribution system is thus a very important step in reducing theoccurrence of discoloured water. The historic role of iron in causing discoloured water cannot bedismissed; although the occurrence of iron appears to have been reduced by the City it is likelythat corroded iron mains will continue to release some iron. However, the large increase indiscoloured water service requests in 2013 compared with 2012 can be attributed to the increasedmanganese concentrations in treated water entering the distribution system and the subsequentaccumulation and release in the system, the significance of which can be seen in the routinedistribution system monitoring and the samples collected from the customers taps in response toservice requests.

461072_WBG121813102642T0R COPYRIGHT 2013 BY CH2M HILL CANADA LIMITED ALL RIGHTS RESERVE COMPANY CONFIDENTIAL


17/26

SECTION 5Investigative Work to Confirm the Source Howdo we know?The City has undertaken extensive work to investigate the causes of discoloured water in thesystem and to make the conclusion that iron and manganese are responsible: Review of historical data to understand what water quality parameters could be attributed to

the discoloured water and their source Consideration of relevant experience and case studies elsewhere On site testing by the City at the WTP to assess performance and the role of treatment

optimization Off site bench-scale testing to identify contributing factors and to evaluate the feasibility of

alternative manganese control strategies Off site analysis of water main samples and lead service lines

46lO72_WBGI218l3lO242TOR 5COPYRIGHT 2 13 BY CH2M HILL CANADA LIMITED ALL RIGHTS RESERVED COMPANY CONFIDENTIAL


18/26


19/26


reducing the ferric dose nor changing to a ferric chloride product with only half as muchmanganese will be much help when trying to get the manganese out of the system as fast aspossible. To reduce the manganese in treated water a combination of control strategies ma y benecessary.Options available to use the distribution system to control discoloured water were also considered.As detailed in the 2011 report to the City entitled Discoloured Water Investigation Report ofFindings a relatively constant pH free chlorine throughout the distribution system continuedapplication of phosphate corrosion inhibitor and continued flushing is the best approach that canbe used to reduce iron concentrations. T he use of sequestering agents that are generallypolyphosphate compounds sometimes called hexametaphosphate was also considered for useThese compounds are often used to reduce the colour and turbidity that result from oxidized ironand manganese. They are often applied to well waters and to distribution systems for reducing thecolour associated with iron release from corrosion scales With i ron they function by preventingthe particles that result from oxidation from becoming large thus resulting in less colour and lessturbidity. With manganese the mechanism is not clear. Th e sequestering agent may function bypreventing the oxidized manganese from becoming large particles thereby reducing the colour andturbidity that result from a given concentration of manganese or they ma y associate with solublemanganese and prevent its oxidation to an insoluble form. Polyphosphate molecules slowly revertto orthophosphate which does not sequester iron and manganese. This reversion may occur in thedistribution system or in washing machines because the reversion occurs faster at highertemperature. When the reversion occurs the iron and manganese are released. concern about polyphosphates is that they ma y associate with the oxidized manganese particlesthat are in distribution system sediment and attached to pipe walls and cause these particles to besuspended in the bulk water. f this were to happen the manganese related colour would probablyincrease. While this is a possibility it has not been demonstrated to occur so we can onlyhypothesize that it might occur

6 2 461072_WBG121813102642T0RCOPYRIGHT 2013 BY CH2M HILL CANADA LIMITED ALL RIGHTS RESERVED COMPANY CONFIDENTIAL


20/26

SECTION 7Reducing the Compounds Responsible forDiscoloured Water from the Distribution SystemWhat do we need to do?Operating the distribution system to manage water quality will help to eliminate the iron andmanganese already in the distribution system: Accelerate the schedule for unidirectional flushing across the system Flush the entire system as soon as possible after eliminating the manganese that is now

entering the system from treated water Continue to regularly clean the storage reservoirs, with all in-town reservoirs cleaned before

summer water quality conditions before June 2 14 Return to the in-town reservoirs again in fall 2 4 to assess the rate and magnitude of iron and

manganese accumulation after one year since the previous cleaning effort; adjust the reservoircleaning frequency accordingly

Review the hydraulic model of the distribution system to identify opportunities to operate thesystem in a hydraulically consistent manner to limit non-routine changes in flow direction, flowsurges, dead zones, or sheer stresses

461072_WBG121813102642T0R 7-ICOPYRIGHT 2 3 BY CH2M HILL CANADA LIMITED ALL RIGHTS RESERVED COMPANY CONFIDENTIAL


21/26


22/26


23/26

SECTION 8RECOMMENDATIONS AND ACTIONS

Table 2: Summary of Recommendations and Actions with Schedule and Cost ImplicationsRecommendation and ction Schedule Approximate Cost Impact

iii Select, test and implement an One year to allow for ost impact to bealternative coagulant demonstration testing, determined by

including 3 months to product selected andtender new product potential secondarysupply contract impacts i.e., residuals

handling)Leverage new pilotplant and City staff fortesting

iv Modify existing plant processes tocontrol manganese: demonstration trial with pre-filter testing underway No impact onpH adjustment allow 2 months for chemical costs; ozone dose optimization results) 40,000 capital

Conduct month of 50 percenttesting after pH trial increase in ozone

operating costs, filter aid polymer dose due to year-roundoptimization Conduct month of ozone usetesting after ozone 20 percenttrial

increase in polymercostv Provide consistent water quality to Implemented No change to

the distribution system chemical cost for pHadjustmentCost impact limited tooperating costs foryear-round use ofozone

vi Operations optimization of 6 to 12 months depending Budget impact willdistribution system on the level of detail depend on level of

develop detail 30 100,000recommendations and to be confirmed)plan for implementation)

461072_WBGI 21813102642T0R OPYRIGHT 2013 SY CH2M HILL CANADA LIMITED ALL RIGHTS RESERVED COMPANY CONFIDENTIAL 8-3


24/26


Table 2: Summary of Recommendations and Actions with Schedule and Cost lmpIicatinsRecommendation and Action Schedule Approximate Cost Impact

vii Cleaning the distribution system: Double the rate at which the Implement in 2014 Double staff effortsystem is unidirectionally flushed and equipment

Test a portion of the system to Implement in spring Allow for labourassess the flushing frequency and effort and2014 tallow two towater quality impact use results analytical needsfour weeks)to determine the flushingschedule for the system

Flush the entire system including Schedule after thethe reservoirs) after the manganese in treated Labour effortmanganese in treated water is water is reducedreduced 0.015 mg L Results expected by Approximately Analyze pipe samples obtained mid-December, 2013 10,000from the system for scalecharacteristics

viii Regularly draw down and inspect the Clean remaining Analytical costs plusin-town reservoirs reservoirs before June staff time to

2014 drawdown and clean the reservoirsTw o reservoirs were

cleaned in October 2013; Allow for all reservoirsschedule next cleaning in in 2014October 2014Use sampling results fromOctober 2014 reservoircleaning to determinecleaning frequency

8-4 COPYRIGHT 2 3 BY CHUM HILL CANADA L IM IT ED A LL RIGHTS RESERVED COMPANY CONFIDENTIAL 46107 2_WEG12 1813 10264UTOR


25/26

SECTION 9Estimated Time to See Improvement How longwill it take?Levels of i ron in the distribution system have declined and are expected to stabilize. Controllingmanganese in treated water will be key to controlling discoloured water but due to the behavior ofmanganese, it is difficult to predict when the discoloured water occurrences will be controlled.Reductions in discoloured water are expected to occur as the source of the discoloured water isreduced and the manganese and to a lesser extent, the iron is flushed out of the system.Whereas the iron is likely stabilizing, the manganese ha s been accumulating to varying degreesover the last four years.The conditions required to realize improvements include a stabilizing water quality b producingwater with minimal levels of manganese, and c practicing unidirectional flushing/reservoirmaintenance to keep the system clean Without these conditions, sustainable improvements willnot be realized.Implementing all of the above recommendations will take upwards of two years to complete,however, i t wil l not take two years before improvements are realized. It s expected thatimprovements will be incremental as progress is made toward implementing the aboverecommendations, and significant improvements may be realized prior to late summer 2014 whendiscoloured water traditionally peaks

451072_W5G121813102642T0R 9-1COPYRIGHT 2013 BY CH2M HILL CANADA L IM IT ED A LL RIGHTS RESERVED COMPANY CONFIDENTIAL


26/26

Winnipeg Discoloured Water report, Jan. 30, 2014

Documents