2005 Pennsylvania 2005 Pennsylvania StormwaterStormwaterManagement SymposiumManagement Symposium

“REMOVAL OF SUSPENDED ORGANIC CONSTITUENTS FROM RUNOFF BY

GEOTEXTILE BAFFLES”

ROGER J. MARINOJOSEPH P. MARTIN

JOHN WALTON

Combined Sewer DataCombined Sewer Data

Pipe networks that convey both sanitary wastewater and Pipe networks that convey both sanitary wastewater and stormwater runoffstormwater runoff

Installed in mid to late 1800Installed in mid to late 1800’’s as solution to public health and s as solution to public health and drainage problemsdrainage problems

Designed primarily to convey stormwater (with sanitary Designed primarily to convey stormwater (with sanitary sewage flow contribution included)sewage flow contribution included)

Overflow (relief) points required to accommodate larger Overflow (relief) points required to accommodate larger storm events storm events

Result Result -- The The ““solutionsolution”” later become the cause of another later become the cause of another problem problem –– Water QualityWater Quality

Prevalence of Combined SewersPrevalence of Combined Sewers

Serve over 40 million residents in nearly 1000 communities in Serve over 40 million residents in nearly 1000 communities in the U.S.the U.S.

15,000 to 20,000 individual outfalls.15,000 to 20,000 individual outfalls.

Located primarily in the Northeast, Midwest and NorthwestLocated primarily in the Northeast, Midwest and Northwest

Regulated by EPA as Regulated by EPA as ““point sourcepoint source”” discharges since their discharges since their outfall locations are knownoutfall locations are known

Piping Layout and Characteristics of a Combined Sewer System (Adapted from Metcalf & Eddy)

Characteristics of CSO EffluentCharacteristics of CSO Effluent

Perceived as a dilute blend of wastewater in Perceived as a dilute blend of wastewater in stormwaterstormwater

Is actually comprised of Is actually comprised of stormwaterstormwater, on, on--going wastewater going wastewater flow, and scouring of flow, and scouring of ““sludge depositssludge deposits”” from the inverts of the from the inverts of the pipe network.pipe network.

Deposition and Decomposition of Solids on Combined Sewer inverts in Dry Weather (Ashley and Hvitved-Jacobsen, 2003)

(15% Of Sanitary Sewage Solids Settle Out In CSOs)

Effects of CSO DischargesEffects of CSO Discharges

Suspended Solids (Turbidity, Sedimentation, etc.)Suspended Solids (Turbidity, Sedimentation, etc.)

PathogensPathogens

Competing Species/ Reduction in biodiversity Competing Species/ Reduction in biodiversity

Thermal IntroductionThermal Introduction

NutrientsNutrients

FloatablesFloatables

Aesthetic and recreational value (diminished public use)Aesthetic and recreational value (diminished public use)

Present Alternative Methods to Manage Overflow VolumesPresent Alternative Methods to Manage Overflow Volumes

Separate sanitary and storm sewer pipesSeparate sanitary and storm sewer pipes

Increase capacity of interceptorsIncrease capacity of interceptors

OffOff--line storageline storage

InIn--line storageline storage

EndEnd--ofof--pipe treatmentpipe treatment

TYPICAL COMBINED SEWER OVERFLOW TYPICAL COMBINED SEWER OVERFLOW CONSTITUENT CONCENTRATIONSCONSTITUENT CONCENTRATIONS

((MoffaMoffa, 1997):, 1997):

ParameterParameter AverageAverage RangeRangeTSS TSS 370 mg/l370 mg/l 273273--551 mg/l551 mg/lVSS VSS 140140 109109--182182BOD5BOD5 115115 5959--222222CODCOD 367367 264264--481481TKNTKN 3.83.8 2.62.6--4.94.9Fecal Fecal coliformcoliform (103/100ml)(103/100ml) 670670 201201--11401140

EPA CSO CONTROL POLICY (GOALS)EPA CSO CONTROL POLICY (GOALS)

NINE MINIMUM CONTROLSNINE MINIMUM CONTROLS

REDUCE OUTFALLS TO 4REDUCE OUTFALLS TO 4--6 OVERFLOWS/ YEAR6 OVERFLOWS/ YEARORORREDUCE MASS DISCHARGE BY 85%REDUCE MASS DISCHARGE BY 85%

End of Pipe Treatment SolutionEnd of Pipe Treatment Solution

Combined Sewer Overflow (CSO)

Sedimentation &Equalization

To WastewaterTreatment Plant (interceptor)

Stormwater catch basin

Wastewater

Riv

er

Diversion Chamber

Combined Sewer

ResidenceBiological Treatment System

Geotextile Baffled

BAFFLE LAYOUTBAFFLE LAYOUT

GOAL - FLOW THROUGH GEOTEXTILE BAFFLES

FLOW THROUGH GEOTEXTILESFLOW THROUGH GEOTEXTILESAND AROUND BAFFLESAND AROUND BAFFLES

ACTUAL FLOW SCENARIOACTUAL FLOW SCENARIO

CONTROLLING PARAMETERS:CONTROLLING PARAMETERS:

HYDRAULIC HEADHYDRAULIC HEAD

DISTANCE BETWEEN BAFFLESDISTANCE BETWEEN BAFFLES

GAP WIDTHGAP WIDTH

GOAL OF GEOTEXTILE BAFFLE SYSTEMGOAL OF GEOTEXTILE BAFFLE SYSTEM

Capture Suspended Solids (200 mg/l to 500 mg/l range)Capture Suspended Solids (200 mg/l to 500 mg/l range)

Smaller particles will be filtered behind larger particles eitheSmaller particles will be filtered behind larger particles either r embedded in geotextile (medium and depth filtration), or on the embedded in geotextile (medium and depth filtration), or on the face of the geotextile (cake filtration)face of the geotextile (cake filtration)

Removal accomplished by rejection and embedmentRemoval accomplished by rejection and embedment

WHAT ARE NONWHAT ARE NON--WOVEN GEOTEXTILES ?WOVEN GEOTEXTILES ?

Planar fabrics made of extruded polypropylene fibers arranged inPlanar fabrics made of extruded polypropylene fibers arranged ina random pattern. a random pattern.

Key parameters;Key parameters;Apparent Opening Size (AOS)Apparent Opening Size (AOS)Permittivity (function of hydraulic conductivity)Permittivity (function of hydraulic conductivity)Internal porosity (storage available)Internal porosity (storage available)

WHY USE GEOTEXTILES ?WHY USE GEOTEXTILES ?

Proven as viable filtration material by Proven as viable filtration material by EyupEyup KorkutKorkut (2003)(2003)

PERMITTIVITY TESTINGPERMITTIVITY TESTING

PERMITTIVITY TEST APPARATUSPERMITTIVITY TEST APPARATUS

PERMITTIVITY TESTINGPERMITTIVITY TESTING

INTRODUCTION OF ANTHRACITEINTRODUCTION OF ANTHRACITE

DOSING EVENTDOSING EVENT

DOSING EVENTDOSING EVENT

DOSING EVENTDOSING EVENT

AFTER SETTLINGAFTER SETTLING

SLOUGHINGSLOUGHING

SLOUGHINGSLOUGHING

RECHECK RESTORED PERMITTIVITY RECHECK RESTORED PERMITTIVITY AFTER SLOUGHINGAFTER SLOUGHING

PERMITTIVITY FOR 10 DOSE RUNPERMITTIVITY FOR 10 DOSE RUN10 OZ/SY COUPONS10 OZ/SY COUPONS

Permittivity Trend

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

Initi

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Dos

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Dos

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Dos

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Dos

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Dos

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Dos

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Ψ (s

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1/8 in. Head 1/4 in. Head

NEXT PHASE NEXT PHASE –– SCALED UP TO PILOT STUDYSCALED UP TO PILOT STUDY

USING 100 QT COOLERS USING 100 QT COOLERS

BAFFLE CONTACT AREA BAFFLE CONTACT AREA –– 1.0 S.F. VS. 0.33 S.F.1.0 S.F. VS. 0.33 S.F.

USED WASTEWATER FROM TREATMENT PLANTUSED WASTEWATER FROM TREATMENT PLANT(DIRECTLY AFTER GRIT CHAMBER)(DIRECTLY AFTER GRIT CHAMBER)

USED COUPONS IN SERIES TO DETERMINE USED COUPONS IN SERIES TO DETERMINE SEQUENTIAL CAPTURE EFFICIENCYSEQUENTIAL CAPTURE EFFICIENCY

RESULTS OF INVESTIGATIONRESULTS OF INVESTIGATION

Defined controlling parameters of Defined controlling parameters of geotextilesgeotextiles (AOS, (AOS, permittivity, and internal storage).permittivity, and internal storage).Performed anthracite analog testing for embedment, Performed anthracite analog testing for embedment, rejection, passrejection, pass--through, permittivity, and recovery. through, permittivity, and recovery. Defined optimal arrangement of baffle layout (distance Defined optimal arrangement of baffle layout (distance between baffles, gap width, hydraulic head).between baffles, gap width, hydraulic head).Determined number of baffles required in sequence to Determined number of baffles required in sequence to allow for full contact with allow for full contact with wastestreamwastestream. . Determined capture potential using offDetermined capture potential using off--thethe--shelf shelf geotextilesgeotextiles

CONCLUSIONCONCLUSION

GeotextilesGeotextiles are effective for suspended solid capture.are effective for suspended solid capture.

Variability of Variability of geotextilegeotextile structure noted affecting critical structure noted affecting critical parametersparameters

May require further optimization study for composite/ May require further optimization study for composite/ designed designed geotextilesgeotextiles instead of, or in combination with, instead of, or in combination with, offoff--thethe--shelf products.shelf products.