System Characterization and Monitoring Activities Julia Moore, P.E. Limno-Tech, Inc

System Characterization and Monitoring Activities

Julia Moore, P.E.Limno-Tech, Inc.

System Characterization and Monitoring Activities2

Expectations of the CSO Policy

The purpose of system characterization [and] monitoring… is initially to assist the CSO community with implementation of the NMCs, and, if necessary, to support development of a LTCP.


ObjectivesDevelop an understanding of the combined sewer system (CSS) and receiving watersAssess CSS design and operating conditions Characterize combined sewage and CSO impacts on receiving watersIdentify gaps in existing information and plan activities to address themAssist with implementation of the NMC


Three Components of System Characterization

Physical characterization of CSSCharacterization of combined sewage and CSOsCharacterization of receiving waters


Physical Characterization

Key sources of existing informationSewer maps, design specifications, as-built drawings CSS, pump station, and WWTP flow records National Climate Data Center (NCDC) rainfall records http://www.ncdc.noaa.gov/oa/ncdc.html

http://www.ncdc.noaa.gov/oa/ncdc.html

http://www.ncdc.noaa.gov/oa/ncdc.html


Physical CharacterizationAdditional sources of existing information

WWTP facilities plansPump station and WWTP performance data (e.g. stress test results)Treatment plant upgrade reportsInfiltration/inflow (I/I) studiesSewer system evaluation surveys (SSES)Storm water master plansGIS databases


Physical CharacterizationLTCP development typically includes:

Delineation of CSS area and sewershedsLocation of CSO outfalls and regulator structures, the WWTP, and pump stationsDescription of CSO receiving waterLand use and estimated impervious cover, by sewershedLayout of major interceptorsHydraulic capacities for the WWTP, CSO regulators, and pump stations


Physical Characterization of Springfield, USA

Delineation of CSS area CSO outfall locationsReceiving waters

Lazy River

Babbling BrookCSSArea

Separate Sewer Area

Satellite Community

Lazy R

iver

Babbling Brook

CSO Area #1

(300 acres)

CSO #3

CSO #1

CSO #2CSO

Area #3(150 acres)

CSO Area #2

(250 acres)

CSO #4Pump station relief

CSO Area

9


Physical CharacterizationLayout of major interceptorsLocation of:

WWTPCSO regulators Pump station

WWTP


Physical CharacterizationGeneral land use and estimated impervious coverLand use categories include:

Parkland or open space (<5% impervious)Low density development (5-35% impervious)Medium density development (35-70% impervious)High density development (>70% impervious)

High Density

Medium Density

Low Density

Open Space



Land Use TabulationParkland/

Open Space

Low Density Development

Medium Density

Development

High Density Development

CSO Area #1

25% 40% 25% 10%

CSO Area #2

10% 25% 45% 20%

CSO Area #3

5% 15% 30% 50%


Impervious Cover Calculation

Example: CSO Area #1 includes:

25% park (3% impervious) 0.8%

40% LDD (25% impervious) 10.0%

25% MDD (50% impervious) 12.5%

10% HDD (75% impervious) 7.5%

Average Impervious Cover: 30.8%


Physical CharacterizationHydraulic analysis should be sufficient to:

Establish capacities for WWTP, pump stations and CSO regulatorsQuantify dry weather and wet weather flows, including flows to CSS from neighboring communitiesDescribe any existing flow metering

Permanent system meters and monitors such as SCADA (Supervisory Control And Data Acquisition)Metering/flow monitoring from previous studies

Identify problem areas and bottlenecks


Pump Station and WWTP Capacities (MGD)

WWTP Average daily flow rate CSS area Separate sewer area Satellite communities

Primary treatment capacitySecondary treatment capacity

4.0 2.5 1.0 0.5

12.06.0

Pump Station Average daily flow rateMaximum pump rate

3.0 6.0


CSS Capacities (MGD)

CSO Area #1 Dry weather flow rateRegulator capacity

1.03.0


0.5 2.0


1.02.0


Flow BalanceQwet = CiA

CSO Area #1wet weather runoff

(30.8% impervious) x(1” rain) x (300 acres)

= 2.5 mg runoff per inch of precipitation







C = runoff coefficient (% imperviousness)i = rainfall intensity

A = area

Flow Balance Diagram

19

Flow Balance Diagram

20


Problem Areas and BottlenecksCompare capacity at key locations in the collection system with peak wet weather flow rates

Intersections of major interceptorsRegulatorsPump stationsCross connections

Additional study may be required in areas that often flood during wet weather


Example—BottleneckPump station capacity should equal or exceed capacity of interceptors delivering flow

to WWTP

From CSOs #1 and #3

From CSO #2

P.S. capacity6 MGD

Max. flow = 5.5 MGD

Max. flow = 2 MGD


Characterization of Combined Sewage and CSOs

Sources of existing information:General WWTP operating dataDischarge monitoring reports (DMRs)Pretreatment program dataFacility planning studiesGIS databasesOther local CSO studiesLiterature


Characterization of Combined Sewage and CSOs

LTCP should include estimates of central tendency (median, EMC) and ranges of concentration for pollutants of concern

Most often: Bacteria, TSS, BODSometimes: NutrientsLess often: Metals and toxics


Average Pollutant Concentrations in Municipal Discharges

Fecal Coliform (MPN/100mL)Source Range MedianUntreated wastewater 106 – 109 -- Wet weather SSOs -- 500,000 CSOs 3 – 406 215,000 Urban storm water 1 – 526 5,081Treated wastewater -- <200



BOD5 (mg/L)Source Range MedianUntreated wastewater 88 – 451 --

Wet weather SSOs 6 – 413 42

CSOs 4 – 696 43

Urban storm water 0.4 – 370 8.6

Treated wastewater -- 30



TSS (mg/L)Source Range MedianUntreated wastewater 118 – 487 --

Wet weather SSOs 10 – 348 91

CSOs 1 – 4,420 127

Urban storm water 0.5 – 4,800 58

Treated wastewater -- 30


Characterization of Receiving Waters

Sources of existing information:Applicable state water quality standardsUSGS streamflow data http://waterdata.usgs.gov/nwis/sw

EPA STORET and BASINS ProgramsState 305(b) Water Quality Assessment ReportsState 303(d) lists of impaired watersOther local water quality assessments

http://waterdata.usgs.gov/nwis/sw

http://waterdata.usgs.gov/nwis/sw



LTCP should document the following:Designated uses for each CSO-impacted waterAvailable water quality, sediment, and biological dataFlow conditions in the CSO receiving water(s)Known impairmentsLocation of sensitive areasPlanned or ongoing TMDL studies


Example Designated Use

Lazy River Secondary Contact Recreation – Used for power boating, sail boating, canoeing and rowing for recreational purposes when surface water flow or impoundment conditions allowNontrout Water – Suitable for propagation and survival of fish


Example Water Quality CriteriaLazy River

Dissolved Oxygen –the minimum daily average shall not be less than 5.0 mg/L, and at no time shall the DO concentration be less than 4.0 mg/LBacteria – the monthly geometric mean, from a minimum of five examinations, shall not exceed 200 MPN/100 mL during all periods when disinfection is practicedpH – from 6.5 to 8.5, inclusiveGarbage and other refuse – none in any amounts


Example Summary of Available Water Quality Data

Statistics DO (mg/L)

Fecal Coliform (May-Sept)

(MPN/100mL)

Fecal Coliform (Oct-Apr)

(MPN/100mL)

pH

Minimum 5.2 80 80 5.7

Maximum 12.7 11,000 9,000 9.0

Average 8.9 1,396 1,041 7.9

Median 8.6 2,306 1,950 8.0

% of timeWQS violated

0 81.8% 0 12.6%

Water Body – Lazy River


Example Designated Use

Babbling BrookPotable Water Supply – Used, after conventional treatment, for drinking, culinary and other domestic purposes, such as inclusion into foods, either directly or indirectlyPrimary Contact Recreation – Used for swimming and other full-body contact activitiesTrout Water – Suitable for propagation and survival of fish, including trout


Example Water Quality CriteriaBabbling Brook

Dissolved Oxygen – the minimum daily average shall not be less than 6.0 mg/L, and at no time shall the concentration be less than 5.0 mg/L Bacteria – the monthly geometric mean, from a minimum of five examinations, shall not exceed 200 MPN/100 mLpH – from 6.5 to 8.5, inclusiveGarbage and other refuse – none in any amounts


Example Summary of Available Water Quality Data

Statistics DO (mg/L)

Fecal Coliform (MPN/100mL)

pH

Minimum 5.6 20 6.3Maximum 14.7 13,000 8.9Average 9.6 993 7.6Median 9.0 230 8.0% of timeWQS violated

0 57.9% 3.4%

Water Body—Babbling Brook


Example Summary of Flow Conditions

Station ID Station Name

Period Drainage Area

01234567 Lazy River at Springfield 1946-present 314 sq. mi.

01237777Babbling Brook at Shelbyville

1973-present 13.9 sq. mi.

Example Summary of Flow Conditions

Month Lazy River (cfs)January 642February 642March 757April 734May 610June 450July 402August 269September 289October 306November 375December 547Average 461 cfs37


What if Local Flow Data are Not Available?

Options for estimating flow:Scale down/up from gage elsewhere in the watershedUse data from similar local watershed with gageEstimate flow using Q=CiA

Example Scale Up from Another Gage

SpringfieldCSO Area

X

Shelbyville Gage on Babbling Brook

39


Example – Scale Up from Another Gage

Babbling Brook at Shelbyville

Drainage Area 13.9 mi2

Annual Average Flow 9.9 cfs

Babbling Brook at Springfield

Drainage Area 17.2 mi2

Annual Average Flow17.2 mi2 = BB flow13.9 mi2 9.9 cfs

BB flow = 12.2 cfs


Example Summary of Known Impairments

The State 303(d) list includes water bodies where existing pollution control activities are not sufficient to attain applicable WQ standards. The list includes several water bodies that pass through Springfield.

Lazy River within Springfield is listed for dissolved oxygen/ oxygen demand, pH, and floatables (NOT bacteria). Babbling Brook from the county line to its mouth at the Lazy River is listed for bacteria and floatables. Upstream portions of the brook are also listed for bacteria.



Sensitive areas per CSO Policy include:Outstanding National Resource WatersNational Marine SanctuariesWaters with threatened and endangered species and their habitatPrimary contact recreation waters, such as beachesPublic drinking water intakesShellfish beds

Sensitive area descriptions should include locational information (e.g., river mile or narrative based on known upstream/downstream distance)


Example Identification of Sensitive Area

Babbling Brook has a designated use of primary contact recreation.

Jebediah Springfield Beach is located on the northeast shore of the brook, approximately 0.3 miles downstream of CSO #1 and 0.1 miles above the confluence with the Lazy River.Jebediah Springfield Beach is open to the public for swimming and wading weekends from Memorial Day to Labor Day.


Monitoring Program

Builds on the system characterizationDesigned to obtain missing, but necessary, information about the CSS operating conditions and CSO impactsSupports implementation of both the NMC and an LTCP


Expectations of the CSO Policy

The permittee should develop a comprehensive, representative monitoring program that measures the frequency, duration, flow rate, volume and pollutant concentration of CSO discharges and assesses the impact of CSOs on the receiving water…


MonitoringGoals and Objectives

Typical objectives:Define hydraulic response of the CSS to rainfallDetermine CSO impacts on receiving water(s)Establish baseline conditions to characterize long-term effects of CSO controlsEvaluate effectiveness of the NMC


Monitoring Program Documentation

Identify monitoring goals and objectivesIdentify data needsDemonstrate that sampling program addressed data needsDocument method for data management and analysis


Monitoring—Data NeedsData needs are very site specific

Closely linked to short and long-term control objectives

Data needs are dependent on the amount of existing information available

Prioritization often required as data needs are typically greater than available budget

Monitoring should be conducted in a manner consistent with applicable state water quality standards


Monitoring - Costs

Usually only 20 to 50 percent of CSOs need full monitoring in a system

Cover range of land usePick largest and/or unique CSOs

Monitoring is expensiveModels “stretch” the value of monitoring


Monitoring—Sampling ProgramTypes of monitoring:

Rain gageCSS flow

Dry weatherWet weather

CSO volume, frequency and pollutant concentrationsReceiving water monitoring

UpstreamCSO impacted zone


Monitoring—Sampling Program

Sampling parameters:FlowCSO effluent and receiving water quality

Bacteria, TSS, BODNutrients (if needed)Metals and toxics (if needed)

Continuous vs. discrete event monitoring


Monitoring Location Selection

Physical logistics and budgetFlow patterns and spatial variability between with stormsPollutants of concern; location of sourcesLocation of sensitive areas

Example of Rainfall Variability


8/10 – 8/12/01 Radar Rainfall Estimates

Screening Potential CSS Monitoring Locations

Outfall # Area (acres)

Landuse Access/ Safety

Concerns

Sensitive Area

Potential Monitoring LocationOpen/

ParkLow

DensityMed.

DensityHigh

Density

1 300 25% 40% 25% 10% X yes

2 250 10% 25% 45% 20% X no

3 150 5% 15% 30% 50% yes

4 0 N/A N/A N/A N/A X yes



Example CSS Monitoring Locations

Rain gagelocation

Electronic meter location

Block test location

Rain gage atlocal airport

WWTP


Monitoring—Sampling Program

Information to be documented:Duration of monitoring programMonitoring locationsFrequency of sampling; number of events sampledPollutants or parameters analyzedSampling protocols, equipment used and analytical methods


Example Block Test Results

Outfall Location Period Results

#4 - pumpstation relief

Foot of Leesome Lane

01/01 – 09/30 At least 22 overflow events

Electronic Meter ResultsCSO 1

Receiving water: BABBLING BROOKDate Rainfall Estimated overflow volume Maximum overflow rate

(inches) (mg) (mgd)1-Apr 0.25 0.000 0.0004-Apr 0.22 0.001 0.0269-Apr 0.93 2.584 48.652

11-Apr 0.84 2.359 40.17915-Apr 0.14 0.396 20.23016-Apr 0.12 0.001 0.26420-Apr 0.02 0.000 0.00022-Apr 0.30 0.778 24.90923-Apr 0.40 0.281 30.6433-May 0.05 0.000 0.0007-May 0.01 0.000 0.000

12-May 0.31 0.646 22.665


Example Receiving Water Monitoring Locations

Weekly water quality monitoring station

Wet weather survey station



Grab Samples vs. Continuous Monitoring

Grab samplingCan be less expensiveCan be simpleOnly represents a single point in time

Continuous monitoringLabor and/or resource intensiveRequires specialized equipment & attentionHighly programmableAllows accurate characterization of water quality integrated over time or flow volume

Example Monitoring



Example Monitoring Results

Receiving Water Boundary ConditionsParameter Units Babbling Brook

Event Mean Concentrations

Base flow Storm flowBOD mg/L 2.7 3.2TSS mg/L 12 94Fecal coliform

MPN/100mL 980 3,800


Special Characterization Studies

Additional studies may be needed in areas where CSOs are causing substantial water quality impacts

Sediment studiesWhole effluent toxicity testingBiological assessmentsIndustrial contributions


Summary

System CharacterizationPhysical characterization of CSSCharacterization of combined sewage and CSOsCharacterization of receiving waters


Summary

Monitoring Track frequency, duration, flow rate, volume and pollutant concentration of CSO dischargesEvaluate impacts of CSOs on the receiving water

Documents

System Characterization and Monitoring Activities Julia Moore, P.E. Limno-Tech, Inc