ST. GEORGE W ATER POLLUTION CONTROL PLANT … · The specific tributary that the St. George WPCP discharges to appears to be located on a clay plain , based on observations of the

ST. GEORGE WATER POLLUTION CONTROL PLANTOPTIMIZATION STUDY

TECHNICAL MEMORANDUM

ASSIMILATIVE CAPACITY ASSESSMENT OF FAIRCHILD CREEK

January 2012Our File: 110-003

GAMSBY AND MANNEROW LIMITEDCONSULTING PROFESSIONAL ENGINEERS

GUELPH – OWEN SOUND – KITCHENER – LISTOWEL – EXETER

110-003 Page i

ST. GEORGE WPCP OPTIMIZATION STUDYTECHNICAL MEMORANDUM – ASSIMILATIVE CAPACITY ASSESSMENTOF FAIRCHILD CREEK

TABLE OF CONTENTS

1.0 INTRODUCTION .......................................................................................................................... 1

2.0 BACKGROUND ............................................................................................................................ 1

2.1 Geology and Physiography ................................................................................................. 12.2 Land Uses............................................................................................................................ 12.3 Fisheries .............................................................................................................................. 12.4 Waste Assimilation ............................................................................................................. 3

3.0 METHODOLOGY ......................................................................................................................... 4

3.1 Overview ............................................................................................................................. 43.2 Historical Data Sources....................................................................................................... 43.3 Pre-Consultation with MOE................................................................................................ 63.4 2010 Stream Monitoring ..................................................................................................... 6

4.0 STREAM QUALITY MONITORING........................................................................................... 8

4.1 OCWA Plant Effluent Data................................................................................................. 84.2 OCWA Stream Monitoring Data ........................................................................................ 94.3 GRCA Stream Monitoring Data........................................................................................ 124.4 MOE PWQMN Stream Monitoring Data ......................................................................... 124.5 Biological Monitoring Data .............................................................................................. 144.6 G&M Stream Monitoring Data ......................................................................................... 16

5.0 STREAM FLOW MONITORING ............................................................................................... 20

5.1 Environment Canada WSC Stream Gauging Data............................................................ 205.2 G&M Stream Gauging Data.............................................................................................. 23

6.0 MINISTRY POLICIES AND PROCEDURES............................................................................ 24

7.0 SUMMARY OF ASSESSMENT RESULTS............................................................................... 25

8.0 DISCUSSION OF RESULTS AND APPLICABILITY TO FUTURE WPCP ........................... 27

8.1 Stream Flow Dilution........................................................................................................ 278.2 Policy 2 Stream Implications ............................................................................................ 278.2.1 E. Coli ............................................................................................................................... 278.2.2 Phosphorus ........................................................................................................................ 288.3 Total Phosphorus Management......................................................................................... 298.4 Nitrates Management ........................................................................................................ 308.5 Effluent Disinfection......................................................................................................... 308.6 BOD-5 and TSS Management .......................................................................................... 318.7 Effluent Hydraulic Loading .............................................................................................. 318.8 Class EA Implications....................................................................................................... 32

9.0 CONCLUSIONS........................................................................................................................... 33

REFERENCES ......................................................................................................................................... 36

110-003 Page ii


LIST OF TABLES

Table 2.1 Fish Species in Fairchild Creek Upstream/Downstream of the WPCP Discharge

Table 4.1 MOE Certificate of Approval Effluent Requirements

Table 4.2 Historical WPCP Effluent Quality Data

Table 4.3 OWCA Historical Stream Quality Data

Table 4.4 GRCA Historical Water Chemistry Data (Laboratory Measured)

Table 4.5 GRCA Historical Water Chemistry Data (Field Measured)

Table 4.6 MOE PWQMN Historical Water Chemistry Data (Laboratory Measured)

Table 4.7 MOE PWQMN Historical Water Chemistry Data (Field Measured)

Table 4.8 Summarized BioMAP Values for 2010

Table 4.9 G&M Stream Quality Data (Laboratory Measured)

Table 4.10 G&M Stream Quality Data (Field Measured)

Table 5.1 Calculated Low Flows Based on WSC Data

Table 5.2 Calculated Low Flows Based on MOE Data

Table 5.3 Calculated Low Flows Based on OFAT Data (WSC Gauge)

Table 5.4 Calculated Low Flows Based on OFAT Data (Plant Discharge)

Table 5.5 Summary of Fairchild Creek Water Flow Monitoring Data

Table 5.6 Stream Flow Contributions for 3 Locations of Interest

Table 9.1 Suggested Effluent Quality Criteria for Future Treatment Plant

LIST OF FIGURESWithin Text

Figure 4.1 OWCA Historical Stream Quality Data - Upstream and Downstream TP

Figure 4.2 OWCA Historical Stream Quality Data - pH and Temperature 2007

Figure 4.3 DO, Temperature and pH Recorded by G&M August 2010

After Text

Figure 1 Fish Sampling Locations

Figure 2 Distribution of Fish Species at Risk

Figure 3 Distribution of Mussel Species at Risk

Figure 4 Fairchild Creek Sampling Locations

Figure 5 Water Survey of Canada Monitoring Location

110-003 Page iii


APPENDICES

Appendix “A” OCWA Historical Monitoring Data for Fairchild Creek

Appendix “B” GRCA Historical Monitoring Data for Fairchild Creek

Appendix “C” PWQMN Historical Monitoring Data for Fairchild Creek

Appendix “D” Benthic Data Collected by NRSI – 2009 and 2010

Appendix “E” G&M Streamflow Monitoring Data for Fairchild Creek – August 2010

Appendix “F” Water Survey of Canada Streamflow Statistics, Fairchild Creek near Brantford

Appendix “G” Letter Re Plant Outfall Location, Huber Environmental Consulting Inc.

Gamsb y and Manne row L im i t e d . Gue l p h , K i t c h e ne r , L i s t owe l , Owen Sound255 Woodlawn Rd W. Suite 210, Guelph, ON N1H 8J1 519-824-8150 fax 519-824-8089 www.gamsby.com

ST. GEORGE WATER POLLUTION CONTROL PLANTOPTIMIZATION STUDY

TECHNICAL MEMORANDUMASSIMILATIVE CAPACITY ASSESSMENT OF FAIRCHILD CREEK

1.0 INTRODUCTION

Gamsby and Mannerow Ltd. (G&M) together with process specialists from Conestoga-Roversand Associates (CRA), University of Western Ontario (UWO) and Huber EnvironmentalConsulting Inc. (HEC) were retained by the St. George Landowners’ Group to complete anOptimization Study of the St. George Water Pollution Control Plant (WPCP).

This Technical Memorandum presents the results of the assimilative capacity assessment of theFairchild Creek receiving stream conducted by the project team. Primary objectives of theassessment were to assess the impact of discharges from the St. George WPCP on the unnamedtributary of Fairchild Creek and to propose future effluent quality criteria for an upgraded orexpanded plant appropriate for the receiving stream. This Memo will form part of the finalOptimization Study document. Further Technical Memoranda will be prepared by the projectteam to cover other aspects of the overall Optimization Study.

2.0 BACKGROUND

2.1 GEOLOGY AND PHYSIOGRAPHY

The Grand River drains an area of approximately 6,800 km2 and is the largest catchment basin insouth-western Ontario. The main stream rises northeast of Dundalk at about 525.78 m(1,725 feet) above sea level and runs a course of 290 km to Lake Erie at Port Maitland.

Fairchild Creek is one of the numerous tributaries of the Grand River and enters the main branchof the Grand River downstream of Brantford near Onondaga. The drainage area of FairchildCreek watershed is approximately 366 square km or approximately five percent of the totalGrand River drainage area. The headwaters of Fairchild Creek rise east of Killean near theHamilton Wentworth and Wellington County Line at an elevation of approximately 314.9 m(1,033 feet) and generally flow south.

110-003 Page 1


The headwaters of Fairchild Creek are located in the Flamborough Plain physiographic region.The Flamborough Plain physiographic region is an area characterized by a dolostone bedrockplain with shallow soils and scattered drumlins. The soils of this region are frequently tooshallow, stony and/or poorly drained to be suitable for agriculture and, consequently, much of thesurrounding area remains in a natural condition relative to most rural landscapes in south-westernOntario. The shallow soils over bedrock in the Sheffield-Rockton area have resulted in the areabeing characterized by swamps, marshes and bedrock outcrops.

However, most of the Fairchild Creek watershed is located in the eastern portion of the NorfolkSand Plain. This is the area of the watershed that has the greatest capability for agriculture andplant growth. Lands in the Norfolk Sand Plain are rated above prime and have been used forspecialty crops grown in few regions in Canada.

The specific tributary that the St. George WPCP discharges to appears to be located on a clayplain, based on observations of the eroded stream channel. Pockets of a thin layer of sand, graveland/or decaying woody vegetation were observed in the area under study, resting on the claycreek bottom.

2.2 LAND USES

Fairchild Creek is located in the Carolinian Forest Zone. Carolinian forests are recognized asbeing a national significant resource and contain flowering dogwood, sassafras, hickory and tuliptrees in forests of ash, maple, oak, beech, and many other species commonly found outside theCarolinian Zone. The warmer climate and rich soils have made the Carolinian zone attractiveboth for farming and for urban expansion.

The headwaters of the Fairchild Creek rise in the 2,400-ha. Beverly Swamp. This swamp spansthree watersheds - Fairchild, Spencer and Bronte Creeks - and is one of the largest forestedwetlands in south-central Ontario. The swamp also maintains hydrological balance byfunctioning as a natural water source and storage area. Other wetlands in the Fairchild Creekwatershed complex (205 ha.) are also important to this region. Again most natural areas aresmall, fragmented and narrowly sinuous along streams and steep slopes.

The Fairchild Creek watershed is mostly rural and farmed with a number of livestock operationsand wetlands. It has been estimated that agricultural land comprises approximately 64 percent ofthe watershed.

The stream channel has a good vegetated buffer zone over most of the upper reaches. In thevicinity of the St. George WPCP discharge it has been estimated that the creek is between 25percent and 50 percent shaded by tree canopy.

2.3 FISHERIES

Fairchild Creek is identified to have a warm water fishery by the Grand River ConservationAuthority (GRCA) and the Ministry of Natural Resources (MNR). Table 2.1 shows the variousspecies of fish captured both upstream (u/s) and downstream (d/s) of the St. George WPCPdischarge (Figure 1). There are no Fish or Mussel Species at Risk identified in Fairchild Creekby Environment Canada (Figures 2 and 3).

110-003 Page 2


Table 2.1. Fish Species in Fairchild Creek Upstream/Downstream of the WPCP Discharge

U/S Discharge in Tributary D/S of WPCP Discharge U/S Main Branch D/S Confluence

Station No. 1-32 1-119 1-119 1-114 1-12 1-12 1-35 1-33 1-52 1-52 - 1-51

Month/YearSampled

Nov/89 Jul/07 Jul/09 Jul//07 Jul/75 May/99 Oct/01 Nov/01 Jul/75 Aug/98 Aug/10 Jul/75

Northern Pike X* X X X

White Sucker X X X X X X X X X X

Golden Redhorse X X

Shorthead Redhorse X

Silver Redhorse X X X

Greater Redhorse X X

Northern Hogsucker X

Common Carp X X X X

Blacknose Dace X X

Creek Chub X X X X X X X

Horneyhead Chub X X X X

Common Shiner X X X X X X X X X

Spotfin Shiner X X

Mimic Shiner X

Rosyface Shiner X X

Blacknose Shiner X

Blackchin Shiner X

Golden Shiner X X

Bluntnose Minnow X X X X X X X X

Fathead Minnow X X

Stonecat X

Largemouth Bass X X

Smallmouth Bass X

Rock Bass X X X X X X X X X

Pumpkinseed X X X X X X

Rainbow Darter X

Fantail Darter X

Johnny Darter X X X X X X X X X

Greenside Darter X

Blackside Darter X X X X X X X

Logperch X X

Notes:Fishery information provided by the Ministry of Natural Resources (MNR).See Figure 1 for station locations.* landowner reports that pike occur here in the spring.

As shown in Table 2.1, there are a wide variety of species of fish both upstream and downstreamof the St. George discharge. The top predatory fish would be the northern pike. Northern Pikehave been captured during the spring, summer and fall downstream of the discharge and havebeen observed by local landowners in the spring upstream of the discharge. The northern pike is

110-003 Page 3


a spring spawner and spawns on heavily vegetated floodplains of rivers, creeks and marshes(Scott & Crossman, Freshwater Fishes of Canada). It is speculated that the upstream reaches ofFairchild Creek may not maintain sufficient base flow to provide a year round residentpopulation of northern pike and that the spawned out adults and the hatched young movedownstream as streamflow drops off in the upper reaches of this unnamed tributary of FairchildCreek. The hatched young northern pike can be 15 cm long by the end of their first summer.

Fish species are not randomly distributed in streams. Consequently, observations of speciesassemblages at a particular time and location are hard to compare because of the varying waterquality requirements of the different species (streamflow, water temperature, dissolved oxygen,food sources etc.) and the ability of fish to move to reaches of the stream that are more suitableto their needs. But generally as shown in Table 2.1, the same species of fish are found bothupstream and downstream of the discharge from the St. George WPCP and in the unnamedtributary receiving the treated discharge and the main branch of Fairchild Creek. White suckers,common shiners, bluntnose minnows, rock bass, pumpkinseed, johnny darters and blacksidedarters were found in all four areas under comparison.

As stated elsewhere in this study, during every visit to the St. George WPCP discharge,numerous minnows would be observed swimming in the actual treated discharge. No attemptwas made to speciate the minnows observed in the discharge but this observation serves as acontinuous bioassay and demonstrates the non-toxic nature of the existing discharge.

One of the species of fish that looks out of place for Fairchild Creek is the logperch. Accordingto Scott & Crossman, logperch inhabit sand, gravel or rocky beaches in lakes and over similarbottom types in large rivers. They also tend to stay offshore in water deeper than 0.9 to 1.2 m(3 to 4 feet) and thus readily escape capture in seine nets. It is likely that the logperch capturedduring the summer in Fairchild Creek probably spend most of their time in the main branch ofthe Grand River.

One of the Habitat Management/Rehabilitation options in the Grand River FisheriesManagement Plant for Fairchild Creek is to increase baseflow. Expanding a WPCP dischargingadvanced treated non-toxic effluent is consistent with this option. At some point highly treatedwastewater should no longer be considered wastewater but just water. An expanded WPCP couldprovide a dependable source of water during the summer low flow periods.

2.4 WASTE ASSIMILATION

Fairchild Creek is the waste water receiver for treated effluent from the St. George WPCP. TheSt. George WPCP is located at 43 Victor Boulevard in the Village of St. George and serves thecommunity of St. George by means of a gravity collection system. The plant serves an estimatedpopulation of 2,300 people. The community is primarily residential with some commercial andinstitutional land uses. Consequently, the waste stream from the community is considered to betypical municipal domestic wastewater. The plant is owned by The County of Brant and operatedunder contract by the Ontario Clean Water Agency (OCWA).

110-003 Page 4


The St. George WPCP is an extended aeration activated sludge plant with a rated hydrauliccapacity of 1,300 m3/day and a design peak flow rate of 3,412 m3/day. The plant operates underMinistry of Environment Certificate of Approval (CofA) No. 9415-6CQKH5 datedJune 24, 2005. Average daily flow through the WPCP in 2009 was 860 m3/day.

When the WPCP was originally designed it discharged into a natural oxbow in an unnamedtributary of Fairchild Creek. Recently, the creek has cut a chute across the oxbow leaving asection of the stream without flowing creek water during low summer flows. The cut-off sectionof the Creek that receives the treated discharge now acts as a tributary receiving drainage fromthe surrounding wetlands and farmed fields, along with the treated wastewater discharge.

3.0 METHODOLOGY

3.1 OVERVIEW

The assimilative capacity assessment included a review of historical data for the St GeorgeWPCP effluent and Fairchild Creek stream quality in addition to the collection and analysis ofadditional data from Fairchild Creek collected during the summer of 2010. Historical streamwater chemistry, biological and streamflow data for Fairchild Creek was obtained from a varietyof sources including:

• Ontario Clean Water Agency (OCWA)• Grand River Conservation Authority (GRCA)• MOE Provincial Water Quality Monitoring Network (PWQMN)• Environment Canada Water Survey of Canada (WSC)• Natural Resource Solutions Inc. (NRSI)• Ministry of Natural Resources (MNR)

A pre-consultation meeting was held with a lead surface water evaluator at the Ontario Ministryof Environment’s (MOE) West-Central Region to obtain their input and guidance on additionalinformation that could be required when conducting the assimilative capacity study for FairchildCreek in the St. George area. As a result, in addition to the above data sources, specific streammonitoring was conducted by G&M during August 2010 to supplement historical data from theabove noted sources. Monitoring included stream gauging, laboratory analysis of water samples,on-site measurement of Dissolved Oxygen (DO), pH, Temperature, and Conductivity [totaldissolved solids (TDS)] and a mixing zone study. Natural Resource Solutions Inc. (NRSI)collected benthic invertebrate information both upstream and downstream of the discharge.Stream monitoring was conducted during the month of August in order to evaluate conditionsduring the stream’s annual low flow period.

3.2 HISTORICAL DATA SOURCES

In accordance with the WPCP CofA, OCWA collects biweekly samples from Fairchild Creekfrom June to August and monthly samples in April and May and from September to December.Sampling is conducted at locations upstream and downstream from the WPCP outfall. Upstreamsamples are collected approximately 20 m upstream of the WPCP outfall, in the oxbow.Downstream samples are collected close to German School Road, the first concessiondownstream of the WPCP. Water quality data is available for the period from January 1, 2004 to

110-003 Page 5


December 31, 2009. Parameters measured include 5-day carbonaceous Biochemical OxygenDemand (cBOD-5), Total Suspended Solids (TSS), Total Phosphorus (TP), Total AmmoniaNitrogen (TAN), Unionized Ammonia (NH3), thermally tolerant forms of Escherichia Coli thatcan survive at 44.5 °C (E. Coli), DO, pH, and temperature.

OWCA also samples final effluent from the plant on a biweekly basis. Effluent quality data wasobtained for the period from January 1, 2004 to December 31, 2009. Parameters measuredinclude cBOD-5, TSS, TP, Total Kjeldahl Nitrogen (TKN), NH3, Nitrite (NO2), Nitrate (NO3),E. Coli, pH, and temperature.

The Grand River Conservation Authority (GRCA) was contacted for water quality and streamflow data from Fairchild Creek in the vicinity of the WPCP outfall. They reported twomonitoring stations in the vicinity, one located upstream from the WPCP at County Road 5(Station ID: 3-437-003), and one located downstream of the WPCP at German School Road(Station ID: 3-437-001). Water quality data was provided for both the upstream and downstreamlocations for five sampling dates between July and October 2009. Parameters measured includeTDS, conductivity, TSS, TAN, TKN, NO2, NO3, TP, DO, Chloride, pH, and temperature.

Environment Canada monitors stream level and streamflow at various locations across Canadathrough their Water Survey of Canada (WSC) Branch. The WSC currently operates onemonitoring station on Fairchild Creek. WSC station 02GB007 is located near the mouth ofFairchild Creek where it flows into the Grand River. Archived discharge and water level data isavailable from 1964 to 2008. Data from 2008 to the present is also available; however this real-time data is provisional and subject to revision.

The Ontario Ministry of Environment (MOE) provincial water quality monitoring network(PWQMN) monitors stream quality across Ontario. PWQMN previously operated MonitoringStation No. 160 184 044 02 on Fairchild Creek, downstream of the WPCP outfall near GermanSchool Road (the location also utilised for downstream sampling by the GRCA and OCWA).Samples were collected by the GRCA and analyzed by PWQMN. Monitoring of station160 184 044 02 started in 1972 and was discontinued in 2006. Over the years a wide variety ofparameters have been measured at this station including bacteria, heavy metals, and someorganics and inorganics. Originally samples were taken monthly but for the period from 2003 to2006, water quality data is only available for three or four samples per year. During that time thePWQMN program measured the parameters previously mentioned as part of the GRCA program.

A “desktop” assimilative capacity assessment for the WPCP was conducted in 2002. It wasconcluded in the “DRAFT” report that Fairchild Creek should be considered a Policy 2 stream inaccordance with MOE Guideline B-1 and the Provincial Water Quality Objectives. Thisdesignation indicates that since background TP is greater than the provincial water qualityobjective (PWQO) of 0.03 mg/L, water quality should not be further degraded and all practicalmeasures shall be undertaken to upgrade the water quality to the objectives. A Policy 2 stream isconsidered to have no assimilative capacity remaining and therefore if additional effluent is to bedischarged, quality of effluent will have to be increased to ensure that loading to the streamremains at most the same or decreases. Based on this conclusion, it was determined that TPeffluent loading from an expanded WPCP should be less than the historical average loading tothe Creek and less than the allowable TP loading to the Creek. The current CofA effluent criteriaobjective for TP is 0.30 mg/L, with a limit of 0.42 mg/L. It was also recommended that the

110-003 Page 6


concentration of NH3-N downstream of the point of discharge should not exceed the PWQO of0.02 mg/L and that chlorine residual should be absent. This report was never finalized.

Figure 4 presents the locations of the historical sampling locations described above.

3.3 PRE-CONSULTATION WITH MOE

A pre-consultation meeting was conducted by HEC with the MOE Technical Support Section ofthe West Central Region in Hamilton on March 12, 2010. Discussions centered on previousenvironmental impact assessment approaches undertaken by others in the area along with theconclusions of these studies. Existing data sources were discussed in addition to the field workthat would be required to obtain a complete understanding of the environmental quality of thearea. The discussion included the local knowledge the MOE employee had of the area, previousMOE studies and potential concerns that should be addressed in the proposed environmentalassessment.

Results of the discussion indicated that phosphorus is expected to be a critical water qualityparameter for the unnamed tributary of Fairchild Creek in the vicinity of the plant. Historicalstream quality data from various agencies indicates phosphorus concentrations both upstreamand downstream of the plant outfall have consistently exceeded the PWQO of 0.03 mg/L forseveral years. It should be noted that this is a widespread occurrence in many streams acrossSouthern Ontario. Based on this historical background water quality, Fairchild Creek isconsidered to be a Policy 2 stream with respect to phosphorous. Policy 2 states “Water qualitywhich presently does not meet the Provincial Water Quality Objectives shall not be degradedfurther and all practical measures shall be taken to upgrade the water quality to the Objectives”.

Diurnal variation in DO levels in the unnamed tributary to Fairchild Creek was also discussed. Itwas suggested that any assimilative capacity study should present real data from both upstreamand downstream of the WPCP discharge, to allow for an evaluation of the potential impactscaused by the WPCP effluent.

It was suggested that the MOE would want to see real data to support any request for anexpansion of the existing St. George WPCP.

3.4 2010 STREAM MONITORING

G&M conducted stream gauging of Fairchild Creek upstream and downstream of the WPCPoutfall on four occasions during August 2010. The most effective upstream monitoring locationwas determined to be at County Road 5. A downstream monitoring location was chosen atGerman School Road. These locations represent the first concessions upstream and downstreamof the WPCP and offer good accessibility for monitoring. Neither of these monitoring sites islocated on the oxbow to which the WPCP discharges effluent; however this was taken intoconsideration when analyzing results. The chosen monitoring locations correspond with thestream monitoring sites of the GRCA.

On each sample date, stream samples were collected for laboratory analysis of the followingparameters; cBOD-5, TSS, TP, TAN, TKN, NO2 and NO3, E. Coli, and chloride. Chloride is auseful tracer chemical as it is very stable and not biologically active or assimilable. TDS,

110-003 Page 7


conductivity, pH and temperature were measured in the field using a Hanna Instruments HI991301 Combination Meter. In addtion, Horiba U-20XD Series Water Quality MonitoringSystems were installed for a period of two weeks at both the upstream and downstream locationsto monitor and record DO, pH and temperature every 15 minutes using a submerged sonde(probe). On a weekly basis, data was downloaded and analyzed.

Efforts were made to locate the submerged sondes in similar stream environments at both theupstream and downstream monitoring locations. This enabled downstream water quality to becompared to upstream water quality, in order to determine the impact of the WPCP dischargeover a complete daily and weekly cycle. Sondes were therefore submerged upstream of riffles inboth monitoring locations. However it should be noted that at the downstream location, waterwas more turbulent than at the upstream location, as the sonde was positioned in-between tworiffles in order to avoid a ponded area with very low flow velocity upstream of the two riffles.

Flow measurements were undertaken using a Marsh-McBirney Flo-Mate 2000 flow meter. Awading rod was used to facilitate measurement of stream velocity at a depth 60% below thestream surface, as per common stream gauging practice for streams with a total depth of less than0.75 m (2.5 feet). Measurements were taken every 0.5 m across the stream. Total flow wascalculated by determining discharge through each defined cross-sectional area of the stream(usually 0.5 m wide) and then summing all values. The following steps were taken:

1. Measure width of each stream section.2. Calculate cross-sectional area of each stream section by taking the average of the depth at

each end of the section and multiplying by the width of the section.3. Calculate discharge through the stream section by multiplying the average of the velocity

at each end of the section by the cross-sectional area of the section.

A small mixing zone study was conducted by HEC and G&M at the confluence of the tributaryreceiving the treated wastewater discharge and the unnamed tributary of Fairchild Creek inAugust 2010. A Hanna Instruments HI 991301 Combination Meter was used to measureconductivity in the receiving tributary and upstream of the confluence in the unnamed tributaryto confirm a significant difference in conductivity readings. A conductivity profile wascompleted across the downstream channel to evaluate the distance for complete mixing.

Benthic invertebrate samples were collected by NRSI both upstream and downstream of theWPCP discharge, in the unnamed tributary to Fairchild Creek, during May 2010. The samplingprocedures followed BioMAP sampling protocols, in order to determine if any potential aquaticimpacts were caused by the discharge of treated wastewater. Standard BioMAP samplingprocedures were used to sample the benthic fauna (Griffiths 1999). Two quantitative (surber)samples were taken at each site, along with a 30-minute qualitative sample. Samples werepreserved in the field using 10% formalin, which was buffered to a pH of 7. Each sample waslabelled internally and externally with a sample number and the total number of jars. Supportingmeasurements of water depth, water velocity, water temperature, pH, and conductivity wererecorded during benthic invertebrate sampling, in order to monitor differences in habitat amongstations. Observations on substrate characteristics were recorded at each sampling station, alongwith observations on algae and macrophyte growth. Photographs were taken to document theexisting substrate composition, as well as general site characteristics.

110-003 Page 8


4.0 STREAM QUALITY MONITORING

The following tables summarize water chemistry and biological data from various sources forFairchild Creek in the vicinity of the WPCP outfall. Plant effluent data is also provided.

4.1 OCWA PLANT EFFLUENT DATA

Table 4.1 provides the current CofA objectives and limits for the WPCP effluent along with thePWQO for various parameters. Loadings are based on compliance limits and a plant ratedcapacity of 1,300 m3/day.

Table 4.1. MOE Certificate of Approval Effluent Requirements

MOE CofA 9415-6CQKH5

Standard cBOD-5 TSSTotal

Ammonia - N TP pHE.Coli

(cfu/100mL)Objectives (mg/L)May-OctNov-April

10 101.03.0

0.30 6.0 to 9.5 150

Limits (mg/L)May-OctNov-April

15 151.23.6

0.42 6.0 to 9.5 200

Loadings (kg/d)May-OctNov-April

19.5 19.51.64.7

0.55 n/a n/a

PWQO (mg/L) n/a n/a 0.020 (NH3) 0.030 6.5 to 8.5 100

Table 4.2 provides a summary of data provided by OCWA for biweekly WPCP effluentsampling between 2004 and 2009 along with data collected by G&M during a comprehensivesampling program during April 2010. Note that the geometric mean density is calculated forE. Coli.

Table 4.2. Historical WPCP Effluent Quality Data

Annual Average WPCP Effluent Data

Period cBOD-5(mg/L)TSS

(mg/L)NH3

(mg/L)TKN

(mg/L)NO3

(mg/L)NO2

(mg/L)NO2+NO3

(mg/L)TP

(mg/L) pHE.Coli

(/100ml)2004 3.2 2.6 2.1 2.7 15.9 0.3 16.3 0.33 7.3 42005 2.8 2.1 0.5 1.4 17.8 0.2 18.7 0.29 7.4 82006 2.5 2.5 0.8 1.7 15.8 0.1 15.8 0.29 7.1 72007 3.4 1.9 0.9 2.3 18.0 1.3 19.2 0.28 7.0 92008 3.2 1.9 0.3 1.0 19.8 0.2 19.9 0.23 7.2 132009 2.6 1.6 0.3 1.1 20.3 1.10 21.4 0.27 7.4 6

Apr. 2010 3.0 2.3 0.8 1.9 22.2 0.92 23.1 0.21 - 47

Review of historical effluent monitoring data indicates overall that the plant has been performingwell and producing a consistent good quality effluent. There have been occasional isolatedexceedances of the objectives for cBOD-5, TSS, TAN, TP, pH and E. coli. Results also indicate

110-003 Page 9


a possible increasing trend in effluent concentration of NO3 and NO2. However, this increasingtrend is not reflected in downstream stream quality data provided by PWQMN and the GRCA.

4.2 OCWA STREAM MONITORING DATA

Table 4.3 presents average annual stream quality data from 2004 to 2009 from OCWA’sbiweekly to monthly stream monitoring program in accordance with the CofA. It should be notedthat reported annual averages are provided, although there are some discrepancies betweenreported values and average values calculated by G&M using the raw data provided by OCWA.In particular there are significant discrepancies with the 2008 upstream data. Calculated valuesare therefore provided with reported values in brackets below.

Table 4.3. OCWA Historical Stream Quality Data

OCWA Reported CofA Stream Quality Data

Description cBOD-5 (mg/L)TSS

(mg/L)TAN

(mg/L)NH3

(mg/L)TP

(mg/L)DO

(mg/L) pHTemp(oC) E.Coli

2004U/S Calculated

(Reported)D/S Calculated

(Reported)

2.2(1.8)2.3

(1.9)

20.7(20.0) 22.1

(23.2)

0.14(0.12) 0.33

(0.33)

0.013(0.000)0.053

(0.020)

0.116(0.100)0.121

(0.110)

7.5(5.7)8.0

(6.0)

7.61(6.38)7.76

(6.50)

13.4(10.1)16.0

(16.0)

147(230)107

(309)2005

U/S Calculated(Reported)

D/S Calculated(Reported)

3.8(3.9)3.8

(3.8)

39.9(39.9)38.7

(38.7)

0.23(0.23)0.22

(0.22)

0.054(0.050) 0.011

(0.010)

0.112

(0.110) 0.166

(0.170)

6.8(6.2) 6.7

(6.7)

7.48(7.47) 7.31

(7.31)

12.8(12.8)16.0

(16.0)

151(151)461

(461)2006



5.3(5.3)4.0

(4.0)

25.7(25.7)30.0

(30.0)

0.31(0.31)0.22

(0.11)

0.018(0.020)0.008

(0.010)

0.125(0.130)0.101

(0.100)

5.2

(5.2)5.8

(5.8)

7.37(7.38) 7.33

(7.30)

13.3

(13.3)13.9

(13.9)

264(832)545

(1400)2007



3.1(2.8)2.7

(2.7)

7.2(5.5)29.6

(29.6)

0.16(0.15) 0.11

(0.11)

0.007(0.007)0.007

(0.007)

0.054 (0.050) 0.064

(0.060)

5.9

(5.0) 5.9

(5.9)

6.68(5.62)6.75

(6.26)

13.4(12.9)13.7

(13.7)

112(110) 204

(191)2008



3.1(3.1)3.6

(3.6)

30.8(18.6)57.9

(56.5)

0.18(60.20)

0.12(0.12)

0.020(0.025) 0.006

(0.010)

0.121(12.30)0.097

(1.420)

6.1(6.1)6.1

(6.1)

7.11(6.60)7.29

(6.54)

12.3(12.0) 15.2

(15.0)

202

(202)330

(330)2009



3.1(3.1)3.5

(3.5)

17.9(17.9)33.1

(33.1)

0.18(0.18)0.11

(0.11)

0.007(0.007)0.013

(0.013)

0.072(0.070) 0.103

(0.100)

8.8

(8.8)7.3

(7.3)

7.06(7.06)7.19

(6.99)

11.7(11.7)13.8

(13.8)

127(127)204

(204)

Refer to Appendix “A” for charts and graphs presenting data from Table 4.3 in more detail.

110-003 Page 10


With the exception of some spikes in the data, upstream and downstream parameters follow thesame trends for the most part, suggesting little impact from the WPCP effluent. In additionconcentrations of the various parameters have remained relatively consistent over the past fiveyears, with no prolonged upward or downward trends observed.

TP is found to regularly exceed the interim PWQO at both upstream and downstream monitoringstations, suggesting that natural background levels of TP are elevated. However, historical streammonitoring data does not indicate a net impact from sewage plant discharge for TP, as illustratedbelow in Figure 4.1.

Fairchild Creek Water Quality MonitoringTP

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

Jan-

04

Apr-0

4

Jul-0

4

Oct-0

4

Jan-

05

Apr-0

5

Jul-0

5

Oct-0

5

Jan-

06

Apr-0

6

Jul-0

6

Oct-0

6

Jan-

07

Apr-0

7

Jul-0

7

Oct-0

7

Jan-

08

Apr-0

8

Jul-0

8

Oct-0

8

Jan-

09

Apr-0

9

Jul-0

9

Oct-0

9Date (mmm-yy)

Co

nce

ntr

atio

n(m

g/L

)

TP Upstream TP Downstream

Figure 4.1 OCWA Historical Stream Quality Data - Upstream and Downstream TP

E. Coli levels consistently exceed the PWQO for “body contact recreation” water bodies, of100 CFU/100 mL (as a monthly geometric mean density). However, as with TP levels, upstreamE. Coli levels are also elevated, indicating that although the WPCP effluent does appear toincrease E. Coli levels in the stream, background levels are already in exceedance of the PWQO.

Taking into account the unionized portion of total ammonia nitrogen, ammonia concentrationsgenerally meet PWQO requirements. pH levels generally also fall within the PWQO acceptablerange, although there are occasionally lower pH readings, which will be further discussed below.

Measured parameters throughout the OCWA program appear to be mostly in agreement withother sampling programs, with the exception of DO and pH, which are observed to be lower thanother annual average values. This could be due to the time of day that sampling occurred. Levelsof DO in streams typically exhibit a diurnal pattern due to the effects of plant photosynthesis.

110-003 Page 11


Highest levels occur in the mid-afternoon and lowest levels in early morning just before sunrise.Photosynthesis can also impact pH levels in stream, although usually to a lesser extent.

Some of the reported pH values are very low and appear to be inaccurate; therefore all pH valuesless than 6.0 were removed from the dataset when performing calculations. However there is acorrelation between low temperatures and low pH within the dataset, as illustrated below inFigure 4.2, which shows unaltered pH and temperature data for both upstream and downstreammonitoring locations during 2007. There is also consistent agreement between upstream anddownstream pH and temperature readings, indicating that the low readings are not random, butmore likely the result of an instrumentation error.

Fairchild Creek Water Quality MonitoringpH - Temperature Correlation 2007

3.00

3.50

4.00

4.50

5.00

5.50

6.00

6.50

7.00

7.50

Jan-07 Mar-07 Apr-07 Jun-07 Jul-07 Sep-07 Nov-07 Dec-07

Date

pH

0

5

10

15

20

25

Tem

per

atu

re(o

C)

pH Upstream

pH Downstream

Temperature Upstream

Temperature Downstream

Figure 4.2 OCWA Historical Stream Quality Data - pH and Temperature 2007

Typically pH is not strongly correlated to temperature. As temperature increases, moredissociation of ions occurs, which results in a higher concentration of hydrogen ions, which tendsto decreases pH slightly. However there is reportedly a greater chance of instrumental error atlower temperatures, due to impedance of the pH membrane glass. This could partially explainwhy pH readings appear to be inaccurate when the water temperature is less than 15oC. Inaddition there is also reportedly greater error when there is a large temperature differencebetween the calibration buffer and sample solution, which could be the case in colder weather.This error cannot be eliminated by the Automatic Temperature Compensation (ATC) built intomost pH meters.

110-003 Page 12


Although instrumentation error due to low water temperature may explain erroneous pH readingsduring the winter months, they do not explain the dip in both temperature and pH readings duringJuly 2007. It is very unlikely that stream temperature could be approximately 10oC with a pHless than 4.0 during the month of July; therefore this data point and others like it have beendisregarded.

4.3 GRCA STREAM MONITORING DATA

Tables 4.4 and 4.5 below summarize water chemistry data for 2009 from the GRCA’s streammonitoring program. Review of their data indicates upstream and downstream water chemistrywas similar with no significant differences in water quality or impacts observed due to theaddition of the WPCP effluent.

Table 4.4. GRCA Historical Water Chemistry Data (Laboratory Measured)

GRCA DataTSS

(mg/L)TAN

(mg/L)TKN

(mg/L)TP

(mg/L)NO3

(mg/L)NO2

(mg/L)Cl

(mg/L)2009

U/SD/S

14.617.6

0.130.07

0.940.86

0.080.08

1.442.40

0.020.01

3744

Table 4.5. GRCA Historical Water Chemistry Data (Field Measured)

GRCA DataTDS

(mg/L)DO

(mg/L) pHTemp(oC)

Conductivity(µS/cm)

2009U/SD/S

480464

10.18.4

8.188.13

16.015.3

735731

Refer to Appendix “B” for charts and graphs presenting data in Tables 4.4 and 4.5 in more detail.

As with the OCWA data, TP concentrations exceed the interim PWQO, although upstream anddownstream values are similar and no negative influence from the plant effluent is observed.Other parameters consistently meet the PWQO.

4.4 MOE PWQMN STREAM MONITORING DATA

Tables 4.6 and 4.7 below summarize PWQMN stream quality data from 2003 to 2006 inFairchild Creek at German School Road. The PWQMN does not have a monitoring station onFairchild Creek upstream of the sewage plant to evaluate net impacts. Measured values for theirstation, which corresponds with the downstream sampling location used by OCWA, GRCA, andG&M, are consistent with the data from other monitoring programs discussed above.

110-003 Page 13


Table 4.6. MOE PWQMN Historical Water Chemistry Data (Laboratory Measured)

MOE PWQMN Data (Downstream)

Year TSS(mg/L)TAN

(mg/L)TKN

(mg/L)TP

(mg/L)NO3

(mg/L)NO2

(mg/LCl

(mg/L)

2003 37 0.205 1.123 0.152 2.99 0.039 49.7

2004 36 0.068 0.880 0.110 3.64 0.032 38.6

2005 68 0.080 0.793 0.147 3.05 0.041 57.2

2006 31 0.049 0.655 0.084 3.17 0.037 58.2

Table 4.7. MOE PWQMN Historical Water Chemistry Data (Field Measured)

MOE PWQMN Data (Downstream)

Year TDS(mg/L)DO

(mg/L) pHTemp(oC)


2003 467 10.8 8.0 10.8 638

2004 431 13.2 8.1 13.5 643

2005 510 11.7 8.1 10.5 724

2006 503 8.8 8.1 18.7 757

Refer to Appendix “C” for charts and graphs presenting data in Tables 4.6 and 4.7 in more detail.

As noted above for the other data sources, TP concentrations exceed the PWQO of 0.03 mg/L forstreams and rivers. However the downstream concentrations measured by PWQMN between2003 and 2006 are not significantly higher than concentrations measured by OCWA upstream ofthe plant outfall between 2004 and 2006. In the PWQMN sampling program TP concentrationsare observed to be higher in the spring months than during the remainder of the year, a trend thatis not observed in other sampling programs. Phosphorus typically attaches to suspended solidsparticles in the water column. The observed increase in TP during the spring could be the resultof spring runoff washing additional solids into the water course.

Historical water chemistry monitoring data is available for this unnamed tributary of FairchildCreek at German School Road prior to the construction of the St. George sewage plant in 1981. Asummary of the PWQMN monitoring data 1972–77, 1978–2002 and 2003-2006 is provided inAppendix “C”. A review of the database for the five years prior to the construction of the WPCPand up to 24 years after the construction of the WPCP indicates that relatively minor changeshave occurred in the creek water quality due to construction of the WPCP.

Some water quality parameters are observed to have increased since construction of the WPCP,including the average cBOD-5 in the creek, which has increased from 1.3 mg/L to 1.5 mg/L,average chloride concentrations, which have nearly doubled from 19 mg/L to 36 mg/L, averagedaytime DO levels, which have increased from 8.4 mg/L to 10.5 mg/L and NO3, which has nearlydoubled from 1.5 mg/L to 2.8 mg/L. Meanwhile, other water quality parameters have remainedsimilar or have been observed to remain relatively constant. Average total ammonia

110-003 Page 14


concentrations have remained almost identical at 0.073 mg/L prior to construction and0.076 mg/L post-construction. Average NO2 concentrations remained similar at 0.0315 mg/L and0.0323 mg/L, while average TKN concentrations have displayed only minor increases from0.69 mg/L to 0.74 mg/L. The average TP concentration in this stretch of Fairchild Creek was0.102 mg/L prior to construction of the WPCP, compared to an average of 0.111 mg/L afterconstruction of the WPCP.

Of all these parameters only DO and TP have a PWQO. The DO criterion was met pre and post-construction of the WPCP, while the TP guideline of 0.03 mg/l was exceeded both pre and post-construction. It should be noted that this guideline was established to avoid excessive plantgrowth in rivers and lakes. During numerous field visits to this tributary of Fairchild Creek, noexcessive algae growth was observed either upstream or downstream of the treated WPCPdischarge. However it should be noted that a large waterlily bed thrives in the immediate vicinityof the discharge pipe in the tributary receiving the WPCP discharge.

4.5 BIOLOGICAL MONITORING DATA

Benthic invertebrates are sampled because they reflect the cumulative effects of the water qualityin their habitat over their complete life cycle; while water chemistry samples are reflective of thewater quality at only one particular time. NRSI conducted benthic invertebrate and water quality(chemistry) monitoring in Fairchild Creek in the spring of 2009 and 2010, under contract with theLandowners’ Group. NRSI is a consulting firm specializing in aquatic and terrestrial biology.

In 2009, NRSI conducted benthic invertebrate sampling and analysis at a total of six monitoringstations, three upstream and three downstream of the treatment plant outfall, in the main channelof the unnamed tributary of Fairchild Creek. See Figure 4 for a map showing 2009 and 2010benthic sampling locations. Benthic invertebrate biomonitoring included detailed speciesidentification and classification by a taxonomist to establish the existing health and biodiversityof Fairchild Creek in the vicinity of the WPCP. Refer to the NRSI report entitled St. GeorgeWastewater Treatment Facility 2009 Aquatic Monitoring Report for more details of this studyand methodology. The conclusion drawn from the NRSI aquatic monitoring work in 2009indicates that there is no distinction between the upstream and downstream monitoring stations.This indicates that the St. George WPCP is not currently impacting aquatic life in the unnamedtributary of Fairchild Creek. The complete 2009 taxa lists, summarized field notes andphotographs replicated from the NRSI report are shown in Appendix “D”. The benthic sampling conducted in 2010 used the BioMAP sampling procedures in an attempt tofurther define any possible differences or impacts to aquatic life immediately downstream of theWPCP discharge compared to upstream. Two quantitative (surber) samples and a qualitative(“qual”) sample were taken both upstream and downstream of the confluence, where theabandoned oxbow tributary connects with the main channel of the unnamed tributary in FairchildCreek. The complete taxa lists, field notes and station photographs of the 2010 benthic samplingare shown in Appendix “D”. The 2010 sampling stations are shown on Figure 4.

Organism density, species diversity and BioMAP (WQId) were calculated for each surbersample. Species diversity and BioMAP (WQIq) were calculated for each “qual” sample. WQId isa water quality index based on abundance or density weighted sensitivity value of organisms,while WQIq is a water quality index based solely on the presence of taxa at the site.

110-003 Page 15


The formula for the density derived index (WQId) is as follows:

WQId = [Σn(eSV i * ln(xi+1))] / [Σnln(xi+1)]Where:

WQId = the quantitative BioMAP water quality index

SVi = sensitivity of the ith taxon

N = number of taxa in the sample

Quantitative decision thresholds based on stream size are as follows:

Creek (Bank full width 16, impaired if < 14

Stream (Bank full width 4 - 16 m): unimpaired if > 12, impaired if < 10

River (Bank full width 16 - 64 m): unimpaired if > 9, impaired if < 7

The formula for the diversity derived index (WQIq) is as follows:

WQIq = 1/k[Σk(SVi)] with k = integer (n/4), k≥4

Where:

WQIq = the qualitative BioMAP water quality index

SVi = the sensitivity of the ith ranked taxon (descending order)

N = the number of taxa at the site

Qualitative decision thresholds based on stream size are as follows:

Creek (Bank full width

110-003 Page 16


As shown in Table 4.8, both the BioMAP(d) and BioMAP(q) scores are higher upstream thandownstream. This suggests that there is a measurable difference in the sensitivity of the benthicinvertebrates upstream to downstream. It must be noted that the downstream station is onlyapproximately 125 m as the crow flies or less than 200 m following the stream course from theconfluence of this unnamed tributary and the WPCP receiver.

Based on the BioMAP(d) and BioMAP(q), both the upstream station and the downstream stationare impaired. Impaired water quality is defined as the occurrence of species that are “out ofplace” for example, the predominance of “stream-dwelling” organisms in a headwater creek, orthe predominance of “lake dwelling” organisms in a river. The general effect of pollution is toshift the occurrence of species upstream from where they would normally occur. Of importancefor this study is that the downstream station has less sensitive organisms and less sensitive taxa.The higher density of benthos clearly implies that the chlorine and ammonia concentrations in theeffluent are not toxic to the infaunal (benthic fauna living on surfaces) benthic community. Thehigher downstream density specifically of filter-feeders, including the chironomids:Cladotanytarsus, Micropsectra and Tanytarsus, the net-spinning caddisflies, blackflies, andperiphyton grazers, including the riffle beetles and baetids mayflies, indicates that the effluentfrom the WPCP is providing fine organic matter, in addition to nutrients (phosphorus andnitrogen), that promote periphyton production. Fine organic matter in suspension provides foodthat directly increases the survival and growth of filter-feeders. Nutrients promote algal growthover hard surfaces, which subsequently increases the survival and growth of grazinginvertebrates.

Increases in the density of both filter feeders and grazing invertebrates are typically founddownstream of non-toxic effluents from WPCPs all across Ontario. The settling of organic matterin localized areas of the creek likely accounts for the higher abundance of worms downstream ofthe WPCP effluent discharge. The lack of visible beds of filamentous algae (e.g. Cladophora) inthe creek is most likely because of a combination of lack of hard substrates (rocks and boulders),heavy shading by riparian trees, turbidity of the water in the creek and grazing activity of thehigher density of benthic invertebrates in this stretch of the creek. Thus although periphytonproduction increases downstream of the WPCP, the standing stock of periphyton does notincrease. Thus although daily DO concentrations likely vary more than under natural streamconditions, the lack of a visible standing stock of filamentous periphyton reduces the risk ofnocturnal anaerobic conditions occurring, which would increase the mortality of benthic macro-invertebrates. Consequently in this case, it is observed that the current stream ecosystem isreadily assimilating and metabolizing the wastes in the WPCP effluent (carbon and nutrients),with few negative environmental consequences. This is likely the reason that there is nomeasurable increase in TP concentrations upstream of the WPCP, compared to one concessiondownstream.

4.6 G&M STREAM MONITORING DATA

Historical water chemistry data from various sources was compared to data collected by G&M inAugust 2010, with data summarized below in Tables 4.9 and 4.10. Note that there was oneanomalous value for TKN at the upstream sampling location which was removed from thedataset.

110-003 Page 17


Table 4.9: G&M Stream Quality Data (Laboratory Measured)

G&M Stream Quality DataAugust 2010

cBOD-5 (mg/L)

TSS(mg/L)

TAN(mg/L)

TKN(mg/L)

TP(mg/L)

NO3(mg/L)

NO2(mg/L)

Cl(mg/L)

E Coli(CFU/100

mL)U/S 2 13 0.05 0.80 0.075 0.9 0.02 29 958D/S 2 10 0.05 0.63 0.070 2.7 0.02 46 984

Table 4.10: G&M Stream Quality Data (Field Measured)

G&M Stream Quality DataAugust 2010

Location TDS(ppm)DO

(mg/L) pHTemp(oC)


Upstream 321 8.16 8.11 21.7 642Downstream 359 9.49 8.03 20.5 712

Refer to Appendix “E” for charts and graphs presenting data in Tables 4.9 and 4.10 in moredetail.

cBOD-5 and TAN were not detected in the samples and therefore the reporting detection limit isshown in then above tables. As with other sampling locations, TP was found to exceed theinterim PWQO at both the upstream and downstream locations, but was not significantlydifferent at each location. TKN and TSS were observed to be higher upstream than downstreamin this sampling program. This is a trend that appears to be unique to the G&M data. Asexpected, NO3 was found to be higher downstream than upstream, while NO2 levels were similarupstream compared to downstream. NO3 and NO2 data from the G&M sampling programgenerally agrees with data collected by the GRCA and PWQMN.

Chloride levels were found to be higher downstream than upstream (an average of 46 mg/Ldownstream as opposed to an average of 29 mg/L upstream). This is expected as sodiumhypochlorite is used as a disinfectant of the final plant effluent and because sodium chloride(salt) is typically found in the fecal matter treated at the WPCP. The plant effluent at the outfallwas sampled on the morning of August 18, 2010 and the chloride concentration was measured as 380 mg/L at that time. This concentration is higher than what is typically found at most WPCPs.However, because this was a single sample it is difficult to evaluate possible reasons for thispotentially elevated value. It could be a result of the regeneration of water softeners in thecommunity, elevated chloride concentrations in the drinking water or naturally occurring brineseeping into the sewer system. Regardless, chloride concentration at this level is considered to benon-toxic to aquatic life and could potentially be medicinal to the gills of fish.

TDS and conductivity were found to be moderately higher downstream compared to upstream.This is in agreement with other sampling programs.

110-003 Page 18


E. Coli levels downstream of the WPCP outfall were found to be higher than upstream values onall dates with the exception of Aug 26, 2010, when a value of 5200 CFU/100 mL was measuredupstream and a value of 2500 CFU/100 mL was measured downstream. As previously discussed,this trend was also observed with the OCWA sampling program. The elevated upstream E. Coliresult indicates that bacteria is contributed to the stream from sources other than the WPCP,possibly from agricultural operations in the watershed.

Concentrations of pH and DO measured during G&M stream monitoring in August 2010 wereconsistently higher upstream than downstream. This is discussed further below based on resultsfrom continuous on-line monitoring of these parameters during a two week period in August2010. DO, pH, and temperature were monitored continuously from August 12 to 26, 2010 withdata electronically recorded every 15 minutes at both the upstream and downstream monitoringlocations.

Figure 4.3 illustrates the variation of DO, pH and temperature over a two week period.

4

5

6

7

8

9

10

11

12

13

12/08

/2010

0:00

12/08

/2010

12:00

13/08

/2010

0:00

13/08

/2010

12:00

14/08

/2010

0:00

14/08

/2010

12:00

15/08

/2010

0:00

15/08

/2010

12:00

16/08

/2010

0:00

16/08

/2010

12:00

17/08

/2010

0:00

17/08

/2010

12:00

18/08

/2010

0:00

18/08

/2010

12:00

19/08

/2010

0:00

19/08

/2010

12:00

20/08

/2010

0:00

20/08

/2010

12:00

21/08

/2010

0:00

21/08

/2010

12:00

22/08

/2010

0:00

22/08

/2010

12:00

23/08

/2010

0:00

23/08

/2010

12:00

24/08

/2010

0:00

24/08

/2010

12:00

25/08

/2010

0:00

25/08

/2010

12:00

26/08

/2010

0:00

26/08

/2010

12:00

Date and Time (dd/mm/yyyy hh:mm)

pH

and

DO

(mg

/L)

15

17

19

21

23

25

27

29

Tem

per

atu

re(o

C)

pH Upstream DO Upstream

pH Downstream DO Downstream

Temp Upstream Temp Downstream

Figure 4.3 DO, Temperature and pH Recorded by G&M, August 2010

The DO measurements exhibit a typical diurnal pattern, as described previously, due to theeffects of photosynthesis. However, macrophytes and attached algae were not observed at eitherof the two monitoring stations, therefore it is speculated that the diurnal cycles are the result ofphytoplankton in the water column. Pond-like, as opposed to riverine conditions were observedin some locations and the concentrations of matter were observed to be insufficient to creatediscolouration of the water. Upstream of the plant outfall, DO levels cycled betweenapproximately 5 mg/L and 11.5 mg/L with an average value of 7.0 mg/L. Downstream of the

110-003 Page 19


plant outfall, DO levels cycled between approximately 7 mg/L and 9 mg/L with an average valueof 7.6 mg/L. There are many possible reasons for the narrower range of DO levels downstream.DO levels are generally increased in areas of increased sunlight; turbulent areas close to riffleswhere more oxygen is transferred from the air; in colder water where more saturation is possibleand in areas that have a lower BOD. Increased variation can sometimes be observed in warmerweather if more biological activity occurs.

At the downstream location, turbulence was increased compared to upstream, which couldaccount for the increased minimum DO values at the downstream location and the increasedoverall average. The sonde (probe) was submerged between two riffles downstream, as opposedto upstream of a riffle at the upstream location. It is hypothesised that the degree of mixing ofwater and transfer of oxygen at the downstream location may dampen diurnal variation over a24 hour period.

The minimum DO concentrations at both stations met the PWQO for DO of 4 mg/L or 47%saturation for warm water biota.

Temperature range was observed to be less downstream (between 17.0oC and 23.4oCdownstream as opposed to between 16.9oC and 28.3oC upstream) and temperatures wereobserved to be generally lower downstream than upstream (an average of 19.8oC downstreamcompared to 22.0oC upstream). The colder water could result in increased minimum DO levelsdownstream and an increased average DO level. Slightly colder water could also decreasebiological activity and decrease variation of DO levels. The decreased temperature range andlower average temperature downstream compared to upstream could also be indicative of lesssunlight at the downstream location due to a greater tree canopy cover through this reach of thewatercourse.

It can be observed that between August 21 and August 24, 2010, temperature and DO levelstemporarily decreased compared to previous days. It should be noted that 45 mm of rain fell inBrantford on August 21; therefore it would be expected that there was significant cloud cover.Cloud cover would slow photosynthesis, thereby reducing DO levels. Increased cloud covercould also be responsible for reduced water temperature. Rain was also recorded on August 22and 23; therefore there was likely increased cloud cover on these days also. Based on the aboveassumptions regarding upstream and downstream DO concentration variation, it would beexpected that cloud cover and subsequently decreased photosynthesis on these particular dayswould have less impact on DO levels at the downstream location, compared to the upstreamlocation. It is hypothesised that the influence of turbulence and decreased water temperaturereduces the impact of diurnal photosynthesis cycles on DO level at the downstream location.This is found to be the case, with significantly less daily variation at the downstream locationbetween August 21 and 24 (a range of between approximately 6.5 mg/L and 7.5 mg/L). Dailyvariation at the upstream location remains more pronounced (between 5 mg/L and 7.5 mg/L),potentially due to the fact that the primary influence on DO levels at this location isphotosynthesis.

The concentration of pH was found to be relatively consistent throughout the two week period,which is normal for a healthy stream. A dip in pH levels to 7.04 is observed at the upstreamlocation on August 24, which was followed by an increase in pH levels to greater than theaverage pH for the remainder of the two week period. This dip in levels occurs after a period of

110-003 Page 20


heavy rain. pH level in streams is impacted by photosynthesis, as photosynthesis uses hydrogenmolecules, which raises the pH. pH is therefore highest in bright sunlight and could decreasefollowing a period of increased cloud cover during a rain event. The rain also likely had a lowerpH, temporarily dropping the pH in the river. The stream’s natural buffering capacity would actto neutralise the impact of the event, leading to an increase in pH levels to normal levels.

Field measurements of in-stream conductivity were measured on August 4, 2010 at the oxbowconfluence just downstream from the plant outfall. Results indicate a conductivity of 625 µS/cmin the main channel upstream of the contribution from the plant, 1,610 µs/cm in the plant effluentflow in the oxbow, and a range of 735 to 755 µS/cm immediately downstream of the confluence.The downstream measurements were taken at several locations across the entire width of thestream channel, a few metres downstream of the confluence between the main stream channeland oxbow channel conveying plant effluent. These measurements indicate rapid mixing and awell dispersed effluent plume due to the narrow range of downstream conductivitymeasurements.

In addition to scientific water quality data gathered, it was noted by direct observation duringseveral site visits that there are active populations of aquatic organisms living in the stream at theplant outfall, which is an indication of a healthy aquatic environment that supports life and hasnot been degraded by plant discharges.

5.0 STREAM FLOW MONITORING

5.1 ENVIRONMENT CANADA WSC STREAM GAUGING DATA

The Water Survey of Canada has operated a continuous water level/streamflow recording gaugeon Fairchild Creek since 1964. The station number is 02GB007 (Fairchild Creek near Brantford)and is located at latitude 43°8’50” N and longitude 80°9’16” W (Figure 5). The creek isconsidered to have “natural” streamflow and has a gross drainage area of 360 km2. A summaryand streamflow statistics of the historical data from this station are shown in Appendix “F”. Thisappendix presents the Monthly Extremes (maximum and minimum) of Daily Discharges,Extremes of Monthly Mean Discharges and Mean Monthly Discharge, along with MonthlyMedian Discharge, Monthly Lower Quartile, Monthly Upper Quartile and Monthly MedianCumulative Runoff Depth for the period on record from January 1964 to December 2008.

Typically, the low flow statistic used by the MOE for continuous discharges to evaluate astream’s assimilative capacity is 7Q20. This is the minimum 7-day average streamflow with arecurrence interval of 20 years – a 5 percent chance of there being inadequate streamflow to meetthe minimum acceptable dilution in any given year. Table 5.1 presents the calculated 7Q20 flowat the above mentioned Water Survey Canada gauge 02GB007 on Fairchild Creek. Minimum 7-day average flows with a recurrence of two years, five years and 10 years are shown forcomparison using different periods of record.

110-003 Page 21


Table 5.1. Calculated Low Flows Based on WSC DataStation 02GB007 - Fairchild Creek near Brantford

Recurrence Interval 1965 to 2005 data 1981 to 2005 data

7Q200.13 cubic metresper second (cms)

0.16 cms

7Q10 0.16 cms 0.20 cms7Q5 0.20 cms 0.23 cms7Q2 0.32 cms 0.34 cms

A source of low flow information that should be discussed to make this evaluation complete isthe published extreme low flow values for Fairchild Creek provided by the MOE. According tothe MOE document Low Flow Characteristics in Ontario, Appendix D: Southwestern/WestCentral Region, October 1990, the extreme low flows for Fairchild Creek are presented in Table5.2.

Table 5.2. Calculated Low Flows Based on MOE Data

Recurrence Interval MOE Data

7Q20 0.084 cms7Q10 0.114 cms7Q5 0.167 cms7Q2 0.316 cms

The values presented in Table 5.2 are based on the analysis of the first 22 years of data collectedat WSC Gauge #02GB007. This database includes the flow years 1965 and 1966, which were thefirst two years of record collection at this station. The yearly minimum 7-day average flow forthese two years is the lowest on record over the past 41 years of data evaluated. These two pointsare an order of magnitude lower than the other 39 years. The recorded low streamflows for 1965and 1966 lowered the line used to estimate low flow frequencies. With a larger database nowavailable, these two individual points have less weight when calculating returning frequencies,which results in higher estimated low streamflows.

Another approach that was used to estimate 7Q20 flows was through the use of the Ontario FlowAssessment Techniques (OFAT) computer models provided by the Ministry of NaturalResources (MNR). The model was developed to help predict low flows in un-gauged areas basedon a GIS platform of site specific data established by the MNR. Flow rates are calculated by themodel based on coordinates of interest. At WSC Gauge #02GB007, OFAT predicts the followingextreme low flows, which are presented in Table 5.3.

110-003 Page 22


Table 5.3. Calculated Low Flows Based on OFAT Data (WSC Gauge)

Recurrence Interval OFAT Data

7Q20 0.2216 cms7Q10 0.2697 cms7Q5 0.3436 cms7Q2 0.5360 cms

The OFAT model predicts higher base flows and preference is given to using the actualmeasured values at the gauge to estimate extreme low flows.

The municipality of St. George is located in the headwaters of one of the tributaries to FairchildCreek. Based on the OFAT analyses, this tributary has a total drainage area of 74.69 km2

upstream of the St. George WPCP. There is no federal or other stream gauges on Fairchild Creekthat monitor streamflow in this area. Estimates of historic streamflow must be based on othernearby streamflows gauges or by using other accepted techniques.

It is a standard accepted hydrological approach to estimate streamflows in un-gauged areas byadjusting the drainage area of a gauged location to an un-gauged location. Ideally, the drainageareas should be within the same size range and have similar soil types, topography andprecipitation patterns. This technique assumes the same contribution of streamflow per squarekilometre of drainage area.

Using this technique to estimate extreme low flows in the unnamed tributary of Fairchild Creekat the confluence with the St. George WPCP discharge, results in estimated streamflows that canbe calculated by dividing the drainage area of the tributary upstream of the WPCP effluentdischarge (74.69 km2) by the gross drainage area of the creek (360 km2). This number is thenmultiplied by the low flow at WSC Gauge #02GB007. Table 5.4 summarizes values calculatedon that basis.

Table 5.4. Calculated Low Flows Based on OFAT (Location of Plant Discharge)

Recurrence Interval 1965 to 2005 data 1981 to 2005 data

7Q20 0.027 cms 0.033 cms7Q10 0.033 cms 0.041 cms7Q5 0.041 cms 0.048 cms7Q2 0.066 cms 0.070 cms

Because of the large difference in size between the two watersheds, the OFAT technique wasalso used to evaluate these low streamflows. The appropriate UTM coordinates were inputted tothe OFAT model to calculate the 7Q20 streamflow at the confluence of the unnamed tributary ofFairchild Creek and the effluent discharge from the St. George WPCP. This model predicted a7Q20 streamflow of 0.043 cms.

110-003 Page 23


Regardless of the approach used; the 7Q20 streamflows in the receiving stream are low, varyingbetween 0.025 and 0.043 cms. The existing St. George WPCP has an approved average day ratedcapacity of 1,300 m3/day or 0.015 cms. For practical purposes it should be assumed that theexisting discharge to the tributary of Fairchild Creek can only be diluted at a ratio of 2 to 1 or 3to 1 under extreme low flows.

It should be noted that the unnamed tributary that receives effluent from the WPCP and the mainbranch of Fairchild Creek, join approximately 3.6 km, as the crow flies, downstream of theWPCP. The conjunction of these two branches of Fairchild Creek is just south ofGovernors Rd. E., which is the second bridge downstream of the existing WPCP effluentdischarge location. At this point, the drainage area increases to over 230 km2. This results in atripling of the drainage area and thus a theoretical tripling of the estimated extreme low streamflows. Based on the existing rated capacity of the WPCP, the minimum dilution of the St. GeorgeWPCP discharge increases to between 6 to 1 and 9 to 1 by the time it reaches that location.

5.2 G&M STREAM GAUGING DATA

A key component of the stream monitoring program in August 2010 was to capturemeasurements during an annual low summer-flow period. Streamflow measurements were takenby using a recently calibrated Marsh McBirney Meter to determine stream velocities at a numberof cross-sections at the two monitoring stations. Table 5.5 presents a summary of streamflowsmeasured upstream and downstream of the WPCP outfall by G&M in August 2010.

Table 5.5. Summary of Fairchild Creek Water Flow Monitoring Data

Fairchild Creek Flow Data (L/s)Date Upstream Downstream

4-Aug-2010 81.1 107.212-Aug-2010 75.6 149.518-Aug-2010 40.7 107.426-Aug-2010 75.4 163.6

Streamflows measurements were taken near the first bridges upstream and downstream of theWPCP, in order to provide safe and reasonable access. Both sites had similar flowcharacteristics. The intent was to determine if there was some correlation between thestreamflows measured near St. George and the long term WSC Gauge, to assist in estimating lowsummer streamflows. Instantaneous streamflow measurements at these upstream anddownstream locations were compared to average daily flow readings measured furtherdownstream by the WSC Gauge.

Downstream flows are consistently greater than upstream flows, as expected, due to thehydraulic contribution of the St. George WPCP plus the increased drainage area movingdownstream. The upstream drainage area is estimated as 69.2 km2 while the downstreamdrainage area is approximately 79.4 km2.

Table 5.6 presents the results of an analyses of streamflow contribution per km2 comparing thetwo monitoring stations near St. George and the WSC Gauge.

110-003 Page 24


Table 5.6. Stream Flow Contributions for three Locations of Interest

DateUpstream Contribution Downstream Contribution Federal GaugeContribution

Gauge(L/s)

L/s perkm2

Gauge(L/s)

L/s perkm2 *

Gauge(L/s)

L/s perkm2

4-Aug-2010 81.1 1.17 107.2 1.22 1,030 2.86

12-Aug-2010 75.6 1.09 149.5 1.76 923 2.56

18-Aug-2010 40.7 0.59 107.4 1.23 579 1.61

26-Aug-2010 75.4 1.09 163.6 1.94 820 2.28

Notes:* An assumed flow of 10 L/s from the WPCP was deducted from the total measured flow prior to calculatingcontribution per drainage area.

Although the contribution difference between the three stations appears to be substantial, it mustbe remembered that the flows are presented in liters per second which are small units. Inaddition, the creek headwaters are located in an area of rock outcrop and shallow soilscontributing little groundwater base flow, while the middle and lower reaches of the watershedare associated with Norfolk Sand Plain and other soil types which have the ability to contributegroundwater base flow to the stream.

Flow downstream of the WPCP is also affected by the quantity of WPCP effluent discharge. Dueto the residential nature of St. George, it is expected that wide fluctuations in daily influentsewage flows are observed. Influent sewage flows are likely higher in the morning and lateafternoon than at other times of the day. It is also expected that sewage flows decreasesignificantly during the night-time hours. These fluctuations are likely partially buffered by thecapacity of the tankage at the WPCP, but it is possible that effluent flows could vary between 5and 20 L/s throughout the course of a day.

6.0 MINISTRY POLICIES AND PROCEDURES

As identified in the MOE publication Deriving Receiving-Water Based, Point Source EffluentRequirements for Ontario Waters, July 1994, any new discharge to Fairchild Creek should benon-toxic. Discharge parameters related to toxicity typically impacted by this Policy arehydrogen sulphide, ammonia, chlorine residual, DO, pH, TSS and BOD. The document statesthat “All new or expanded effluent discharges must not be acutely lethal as defined by meeting a96-hr 50% lethal concentration (LC50) whole effluent toxicity test using rainbow trout anddaphnia magna”. This statement specifically relates to Policy 5 guidelines for Mixing Zones.This Policy is especially pertinent in the case of St. George because the existing WPCP is locatedin the upstream portion of the watershed, therefore very little dilution can be guaranteed by theunnamed tributary at the proposed discharge location. Under a worst case scenario, it could beconsidered that discharge is to a “dry” ditch. The Policy document does allow treated wastewaterdischarges to “dry” ditches.

110-003 Page 25


The above referenced document also discusses Policy 2 streams. Policy 2 states: “Water qualitywhich presently does not meet the Provincial Water Quality Objectives (PWQO) shall not bedegraded and all practical measures shall be undertaken to upgrade the water quality to theobjectives”. Based on the many years of chemical monitoring both upstream and downstream inthe unnamed tributary of Fairchild Creek, this reach of the stream is expected to be considered aPolicy 2 stream for TP and E.Coli. The MOE’s PWQOs for these parameters are exceeded bothupstream and downstream of the WPCP. Recent TP data suggests that in-stream concentrationsof TP do not actually increase as a result of the WPCP discharge. However, due to the TPPolicy 2 designation, it is likely that, should the WPCP be modified or expanded, the bestavailable wastewater treatment technology would be required to address phosphorus removal.

Procedure F-5-1 Determination of Treatment Requirements for Municipal and Private SewageTreatment Works Discharging to Surface Waters requires that a receiving water assessment beconducted for any new or expanded Municipal Sewage Treatment System discharging to surfacewater. One of the purposes of this study was to comply with this procedure.

Effluent disinfection requirements are laid out in Procedure F-5-4 Effluent DisinfectionRequirements for Sewage Works Discharging to Surface Waters. This procedure states “allmunicipal sewage works require disinfection”. This procedure has previously been interpreted tomean that a treatment facility does not necessarily have to install an ultra violet (UV) orchlorination disinfection system, but that the treatment process must produce an effluent thatresults in less than 200 CFU of E.coli per 100 mL. In some recreational areas, this criterion mayeven be more restrictive seasonally. The existing WPCP meets this procedure.

Procedure F-8-1 Determination of Phosphorus Removal Requirements for Sewage TreatmentWorks identifies that there is, and will likely not be, any published requirement for phosphorusremoval at the proposed wastewater treatment facility, as the rated capacity of the full facilitywill be less than 4,546 m3/day. However, it is speculated that phosphorus removal will bestipulated by the Region based on typical “Regional Approaches”. The West Central Region ofthe MOE required phosphorus removal when the original WPCP was designed in 1979 andadvanced phosphorus removal (enhanced filtration) during the most recent WPCP expansion.Therefore, it is expected that advanced phosphorus removal will be a requirement for any futureexpansions.

7.0 SUMMARY OF ASSESSMENT RESULTS

1. Analysis of historical stream monitoring data as well as data gathered during August 2010 insupport of this study indicates no significant difference in water quality upstream anddownstream of the WPCP in terms of cBOD-5, TP, NH3, DO, pH, and temperature.

2. Concentration of NO3 is consistently greater downstream of the plant outfall. This result isexpected as the plant discharges effluent with NO3 concentrations typically in the mid 20’smg/L. The plant is an extended aeration activated sludge plant that includes nitrification (i.e.oxidation of ammonia to NO3), but the plant is not designed to de-nitrify [i.e. reduce NO3 tonitrogen gas (N2(g))] for total nitrogen reduction. The current CofA does not stipulate anyeffluent quality criteria for NO3-N, only ammonia nitrogen. The MOE has no PWQO forNO3 in surface water.

110-003 Page 26


3. Concentration of chloride is consistently higher downstream of the St George WPCP, whichis expected as the plant disinfects treated effluent with continuous trickle dosing of liquidsodium hypochlorite (NaOCl). Chlorides are also excreted by the population connected tothe sewage system.

4. Disinfection is followed by chemical dechlorination at the plant through dosing of liquidsodium bisulphite (NaHSO3). As a result of dechlorination of the WPCP effluent, thedischarge to Fairchild Creek should not be toxic. This conclusion is supported by numerousminnows being regularly observed at the end of the discharge pipe.

5. Concentration of E. coli is consistently higher downstream of the sewage plant. The WPCPuses chlorination and dechlorination to eliminate the bacteria contained within its discharge.Based on effluent monitoring, the WPCP does not appear to be the source of increasedbacteria downstream of the discharge location. It is inferred that E. Coli may be introducedto the stream from other sources including leaky septic tanks in unserviced areas or stormwater discharge.

6. The DO levels in-stream are very similar, both upstream and downstream of the WPCPeffluent discharge, in the main branch of the unnamed tributary of Fairchild Creek. Thiswould infer that the TP concentration in the WPCP discharge is not resulting in excess plantgrowth downstream and that the BOD being discharged has not resulted in a measurable DOsag in the river.

7. Minnows were observed swimming at the mouth of the discharge pipe in the stranded oxbowtributary and ponded areas during all visits in the summer of 2010. This supports theconclusion that the existing WPCP is operating well and has a non-toxic effluent.

8. Conductivity tends to be slightly greater downstream of the plant compared to upstream,while TSS tends to be moderately greater downstream of the plant. The increase inconductivity relates to the increased concentration of chlorides in the discharge, but theincrease in TSS is likely not related to the WPCP effluent, as the discharge contains lowerconcentrations of TSS than are found upstream and downstream of the treatment plant. Theincrease in TSS could be the result of the creek trying to re-establish its gradeline as a resultof the recent creation of a chute, cutting off part of an oxbow.

9. The review of OCWA and PWQMN datasets, which cover several years, do not indicate anyapparent trends with respect to water quality parameters over time.

10. The GRCA upstream and downstream monitoring data revealed no exceedances of thePWQOs that could be attributed to the WPCP.

11. The mixing zone study indicated rapid mixing of the branch receiving WPCP effluent andthe main branch of the unnamed tributary of Fairchild Creek. This is consistent with theMOE’s approach to mixing zones, which should be as small as possible.

12. Excessive attached algae and/or macrophytes were not observed in either the upstream ordownstream monitoring locations in the unnamed tributary. This would infer that the TPlevels being discharged by the WPCP are not seriously impacting Creek health.

13. The NRSI 2009 Aquatic Monitoring Report concluded that: “For 2009, the benthicinvertebrate and water quality data indicates that there is no distinction between reference(upstream) and exposure (downstream) areas on Fairchild Creek”.

14. The 2010 benthic sampling study revealed an organic enrichment immediately below theconfluence with the WPCP discharge, using the BioMAP sampling procedure. The higherdensity of organisms clearly showed that the discharge was not toxic. Even though thereappears to be organic enrichment based on the increased number of organisms, it appears

110-003 Page 27


that within less than 200 m below the confluence, the current ecosystem is readilyassimilating and metabolizing the residual concentrations in the WPCP effluent (carbon,phosphorus and nitrogen), with few if any environmental consequences.

8.0 DISCUSSION OF RESULTS AND APPLICABILITY TO FUTURE WPCP

8.1 STREAM FLOW DILUTION

All data collected and analyzed as part of this study indicates that the existing St. George WPCPis not seriously negatively impacting the downstream ecology of the unnamed tributary ofFairchild Creek. Extreme low flows (7Q20) in the receiving stream only provide a 2 to 1 or 3 to1 dilution for current treated wastewater discharge flows. Approximately 3.6 km downstream,this dilution increases to between 6 to 1 and 9 to 1, below the confluence with the main

ST. GEORGE W ATER POLLUTION CONTROL PLANT … · The specific tributary that the St. George WPCP discharges to appears to be located on a clay plain , based on observations of the

Documents