Other:

A REMEDIAL ACTION PLANNEW BEDFORD HARBOR SUPERRJND SITE

PRESENTED AT

ENVIRONMENTAL PROTECTION AGENCYNEW ENGLAND REGION

BOSTON, MASSACHUSETTS 02203-2211

OCTOBER 19, 1988

PRESENTATION OVERVIEW

1. BACKGROUND

t PCB PROBLEMt REMEDIAL ALTERNATIVES UNDER CONSIDERATIONt ASSESSMENT

2. ENVIRONMENTAL SETTING

3. REMEDIAL ACTION CONCEPT

t IMPACT OF CAPPING ON PCB FLUX RATES

• CAPPING CONCEPT- OVERVIEW- ENGINEERING FEASIBILITY- CONSTRUCTION METHODOLOGY- ENVIRONMENTAL IMPACT- COST ESTIMATES

4. SUMMARY ASSESSMENT OF PROPOSED REMEDIAL ACTIONPLAN

5. CONCLUSION

HISTORY OF PCB PROBLEM IN NEW BEDFORD HARBOR

1976-1979 PCB CONTAMINATION DOCUMENTED IN NEW BEDFORD HARBOR BY EPA AND ACADEMIC SCIENTISTS, MASSACHUSETTS CLOSES ESTUARY TO FISHING

1982 NEW BEDFORD HARBOR NAMED BY EPA TO NATIONA L PRIORITIE S LIST OF HAZARDOUS WASTE SITES (SUPERFUND SITE)

1983 N U S W O R K P L A N - R E M E D I A L INVESTIGATION AND FEASIBILITY STUDY

1984 NUS FAST TRACK FEASIBILITY STUDY (FS) UPPER ESTUARY

1985-88 U S A R M Y C O R P S E N G I N E E R I N G FEASIBILITY STUDY, EVALUATE CAD AND CDF APPROACHES

1987 E B A S C O A N A L Y S I S OF REMEDIA L TECHNOLOGIE S FOR NEW BEDFORD HARBOR, FEASIBILITY STUDY

1987­ US ARMY CORPS/EPA PILOT STUDY ­DREDGING AND DISPOSAL ALTERNATIVES

HABITATS AND BATHYMETRY

MARSH

• TIDAL FLAT

DEPTH BELOW LLW (FT)

NEW BEDFORD,/J

PPM10-50 PPM>50 PPM

ITAL PCBs (PPHl 10-50

• 50-100 100-500 500-1000

l > 1 0 0 0

fflnaa

CONC. (PPM) CD <200

200-1000

1000-2000

>2000

DREDGE CATAGORIESONE <100 PPHTWO 100-200 PPMTHREE >200 PPM

V 1 Jl=NE W BEDFOR

CONC. (PPM) 100-200

• 200-1000 1000-2000 >2000

DREDGEONETWOTHREE

CATAGORIES <200 PPM 200-400 PPM

>400 PPM

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CRITERIA FOR REMEDIAL ACTION PLAN*

t EFFECTIVENESS- RELIABILITY - SIGNIFICANTLY AND PERMANENTLY

REDUCE TOXICITY, MOBILITY, AND VOLUME

t IMPLEMENTATION - T E C H N I C A L , I N S T I T U T I O N A L ,

ADMINISTRATIVE FEASIBILITY TO INSTALL, MONITOR AND MAINTAIN TECHNOLOGY

• COSTS - DIRECT - INDIRECT COSTS- OPERATION AND MAINTENANCE COSTS

*IN ACCORDANCE WITH

CERCLA FEASIBILITY (CERCLA-FS)NATIONAL CONTINGENCY PLAN (NCP)SUPERFUND AMENDMENTS AND REAUTHORIZATIONACT (SARA)

RECOMMENDED APPROACHES

NUS FAST TRACK FEASIBILITY STUDYREMEDIAL ACTION ALTERNATIVES (UPPER ESTUARY)

• HYDRAULIC CONTROL OF RIVER WITH SEDIMENTCAPPING

t SEDIMENT DREDGING WITH IN HARBOR DISPOSAL(LINED OR PARTIALLY LINED) (CONTAINMENT DIKEFACILITY, CDF)

t DREDGING WITH UPLAND DISPOSAL

t BURIAL (CLEAN SEDIMENT CAP) IN ESTUARY BOTTOM(CONFINED AQUATIC DISPOSAL, CAD)

EPA/US ARMY CORPS PILOT STUDY -DREDGING/CAPPING EVALUATION

EVALUATE DREDGING TECHNOLOGY

- H Y D R A U L I C P IPEL INE C U T T E R H E A D (WITH/WITHOUT MATCH BOX)

- MUD CAT (HORIZONTAL AUGER)

CONFINED DISPOSAL FACILITY (CDF)

AREA - 125,000 FT2DREDGED MATERIAL - 10,000 CU YD (5,000

CU YD CONTAMINATED)DIKE LENGTH - 1700 FTDIKE VOLUME - 24,500 CU YD

DREDGED SEDIMENT PCB CONCENTRATION ­100 PPMGEOFABRIC, LINEDPRIMARY/SECONDARY CELLFINAL CAP VOLUME - 5,000 CU YD

CONFINED AQUATIC DISPOSAL (CAD)SIZE - 250 FT X 250 FTDREDGED MATERIAL - 5,000 CU YD (2500 CU YDCONTAMINATED)CAP THICKNESS - 2 FT

CONCERNS WITH PRESENT DREDGING/CAPPING APPROACHES

• HIGH RISK OF CONTAMINANT RELEASE

I HANDLE LARGE VOLUMES CONTAMINATED SEDIMENTS

i LARGE SCALE ENVIRONMENTAL IMPACT

I UNFAVORABLE COST BENEFIT PROBABLE

• CHANGE PHYSICAL CHARACTER OF ESTUARY

I LOSS OF HABITAT

I NOT APPLICABLE TO "HOT SPOT"

I LIMITED EXPERIENCE WITH APPROACHES

I SIGNIFICANT ENGINEERING PROBLEMS

PHYSICAL

SMALL URBAN ESTUARY

LOW FRESHWATER INPUT

PRIMARILY TIDAL CIRCULATION

HURRICANE BARRIER ISOLATES ESTUARY FROMOFFSHORE WATERS (STORM SURGES)

GEOLOGICAL

t DEPOSITIONS. ENVIRONMENT

t COMPLEX TIDAL FLATS, SHALLOW BASINS AND TIDAL CHANNELS; SIGNIFICANT HUMAN ALTERATIONS - DREDGING AND FILLING

t ORGANIC-RICH SILTS/CLAYS IN UPPER ESTUARY TO COARSER SANDS/GRAVELS IN LOWER ESTUARY

§ NET SEDIMENT TRANSPORT INTO HARBOR FROM BUZZARDS BAY

BIOLOGICAL

t ESTUARINE

• EUTROPHIC

t HIGH POLLUTANT LOAD

t SUBTIDAL: MUD BOTTOM, HIGH TURBIDITY, PLANKTON-BASED FOOD CHAIN

t INTERTIDAL: MUD FLATS AND SALT MARSH; SALT MARSH IS 80% HIGH MARSH CONTAINING SPARTINA PATENS (SALT MEADOW CORDGRASS)

FLUX/AREA

100

80­

UJ a: 68. 4

60­

40­

LU O DC

20.2 20-

7.3

2.3 0.6 0.0 0.0

0-5 5-10 10-50 '50-100 100- 500- >1000 500 1000

SURFACE SEDIMENT CONCENTRATION (ppm)

HISTOGRAM OF PCB FLUX PER UNIT AREA FROM THE SEA FLOOR

INTO THE WATER COLUMN VERSUS SURFACE SEDIMENT PCB

CONCENTRATION CONTOURS (PPM). CALCULATIONS ARE

NONDIMENSIONALIZED WITH TOTAL FLUX INTEGRATED OVER ALL

CONTOUR INTERVALS.

AREA

100

80­

< UJ

< 60­

Z 40-( 39.0 UJ o UJ D_

23.8

20- 17.5

7.4 6.6 3.5 2.2

0-5 5-10 10-50 50-100 100- 500- >1000 500 1000

SURFACE SEDIMENT CONCENTRATION (ppm)

HISTOGRAM OF BOTTOM AREA VERSUS SURFACE SEDIMENT PCB

C O N C E N T R A T I O N C O N T O U R S ( P P M ) . V A L U E S A R E

NONDIMENSIONALIZED WITH THE TOTAL AREA (NORTH OF THE

HURRICANE BARRIER) HAVING PCB SURFACE SEDIMENT

CONCENTRATIONS GREATER THAN 1 PPM.

AREA WEIGHTED FLUX

100

80­

31 O

60-

< 52.6 UJ

<

40-

24.5 LU O cc 20-

16 .7 LJ

2 .9 3.2 0.0 0. 1

0-5 ' 5-10 ' 10-50 ' 50-100 100­ 500­ >1000 500 1000

SURFACE SEDIMENT CONCENTRATION (ppm)

HISTOGRAM OF AREA WEIGHTED PCB FLUX FROM THE SURFACESEDIMENTS TO THE WATER COLUMN VERSUS SURFACE SEDIMENTPCB CONCENTRATION CONTOURS (PPM). VALUES ARENONDIMENSIONALIZED WITH TOTAL FLUX INTEGRATED OVER THEENTIRE ESTUARY (NORTH OF THE HURRICANE BARRIER).

••

CUMULATIVE FLUX (AREA WEIGHTED)

100 100.0 100.0 99.9 97.0

93.8

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0-5 5-10 10-50 50-100 100­ 500­ >1000 500 1000

SURFACE SEDIMENT CONCENTRATION (ppm)

HISTOGRAM OF THE CUMULATIVE AREA WEIGHTED PCB FLUX FROM THE SURFACE SEDIMENTS TO THE WATER COLUMN VERSUS SURFACE SEDIMENT PCB CONCENTRATION CONTOURS (PPM). THE INTEGRATION HAS BEEN DONE FROM HIGHER TO LOWER PCB CONCENTRATION LEVELS. THE AREA NOTED FOR EACH INTERVAL IS THE CUMULATIVE AREA (ACRES).

CAPPING VOLUME REQUIREMENTS

PCB SEDIMENT CUMULATIVE CUMULATIVE CONCENTRATIONS AREA VOLUME

(PPM) (ACRES) (CU YD)

1000-> 21 50,007500-> 56 133,351100-> 120 285,75450-> 193 459,58710-> 428 1,019,1885-> 601 1,431,150l-> 985 2,345,560

UPPER ESTUARY(<MHW) 257 611,988(<MSL) 204 485,781(<MLW) 175 416,724

ASSUME CAP THICKNESS 45 CM (1.476 FT)

ADVANTAGES OF CAPPING APPROACH

0 WIDELY USED PRACTICE

0 SUCCESSFULLY IMPLEMENTED (ROTTERDAM; 1981; SEATTLE, 1984; NEW YORK EXP. MUD DUMP, 1983; LONG ISLAND SOUND, 1980'S)

0 EFFECTIVELY ISOLATE WASTE

0 COST EFFECTIVE

0 TECHNOLOGY AND EQUIPMENT READILY AVAILABLE

0 NO HAZARDOUS MATERIAL IS HANDLED, RISK OF RELEASE MINIMAL

0 CAPPING MATERIAL ABUNDANT AND FREE (OFFSHORE BORROW SITE)

REMEDIAL ACTION PLAN SUMMARYINLET MODIFICATION - CAPPING

• CONSTRUCT TEMPORARY DAM (WITH VARIABLE HEIGHTWEIR) AT COGGESHALL ST. BRIDGE

- WEIR AT MHW - CONTROL CIRCULATIONAND WATER LEVELDURING CAPPING

- WEIR AT MLW - TIDAL UPPER ESTUARY,SALINITY RANGETYPICAL PRESENT,TIDAL RANGE ANDFLOW REDUCED BY 65%

t CAP UPPER ESTUARY SEDIMENTS

- CAP ENTIRE UPPER ESTUARY, OBTAIN CLEANMATERIAL FROM OFFSHORE OR LAND BORROWPIT

- GEOFABRIC COVERS- GRAVEL-STONE EROSION PROTECTION

(18 ACRES, HOT SPOT AND VICINITY)- CAPPING DEPTH - 45 CM

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100 200 300 400 SOO SOO 7OO BOO DISTANCE FROM WESTERN SHORE (FT)

FIXED BRIDGE

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Coggevholl Si /

Cross sections of the upper estuary showing thepre and post cap conditions.

EXISTING WITH 45 CM CAP WITH 45 CM CAP AND CONDITIONS 35% REDUCED TIDAL_RANGE

BELOW MLW J MLW-MSL I MARSH

AREAL EXTENT OF PRESENT AND POTENTIAL BIOLOGICALHABITATS ASSUMING A 45 CM CAP OVER THE ENTIRE UPPERACUSHNET RIVER ESTUARY NORTH OF THE COGGESHALL ST.BRIDGE AND A WEIR REDUCING THE TIDAL RANGE TO 35% OFPRESENT RANGE. (MSL = MEAN SEA LEVEL; MSLW = MEANSPRING LOW WATER; MPSHW = MAXIMUM PROBABLE SPRINGHIGH WATER).

HABITAT DEPTH AREAL EXTENT (ACRES)ZONE

PRESENT CAP ONLY CAP AND WEIR

SALT MARSH MPSHW­ 53 83 48 MSL

INTERTIDAL MSL­ 29 54 37 MUD FLAT MSLW

INTERTIDAL MSL­ 12 12 RIP-RAP MSLW CHANNEL

SUBTIDAL <MSLW 175 102 119 MUD

SUBTIDAL <MSLW RIP-RAP CHANNEL

NEWLY >MPSHW 35 CREATED UPLAND

TOTAL <MPSHW 257 257 257

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ACUSHNET LOWER RIVER HARBOR

CAP TOO THICK

3.7 -MH W

t3 &MSL Ld -...«* L_ DESIRED CAP

0 •• MLW

NO RISE IN HIGHEST WATER LEVEL (PONDING) AS LONG AS HEIGHT IS LESS THAN MHW.

MAXIMUM CAP THICKNESS: TIDAL RANGE + MLW DEPTH.

(3.7 ft + 0.5 ft = 4.2 ft)

PREFERABLE TO HAVE CAP LOWER THAN MSL

(1.85ft + 0.5ft = 2.35ft)

PCB AND METALS: EFFECT OF CAPPING UPPER ESTUARY

PARAMETER % MASS CAPPED*

CHROMIUM 34COPPER 30LEAD 46ZINC 68

PCB 95 (**)

* BASED ON TOTAL MASS (0-12 IN.) IN ESTUARY (NORTHOF HURRICANE BARRIER)

** BASED ON TOTAL ESTUARY MASS FLUX RATE (KG/YR)

Salinity (ppt)

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CHANGES IN SALINITY RATIO AFTER DAM CLOSING

1.000

RIVER FLOW

/*;. / Low (1/2 mean)

0.200-- 777;-; response time: *""'-c./(2x mean] 110 days = 5%original '"'•'•*•*JJ..

0.000 10 20 30 40 50 60 70 80 90 100

Time (days) after Dam Closing

Salinity ratio (non dimensional, 1.0 - 26 ppt) versus time(days) after closing of Coggeshall St. channel. AcushnetRiver flows are low (one-half mean), mean (0.85 m^/sec) andhigh (twice mean).

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Inlet basin hydrodynamic model channel gridsystem for the upper estuary.

Inlet basin hydrodynamic model predicted flow velocities andassociated cross-sectional areas for the channel sectionsshown in Figure 4-3. Values are for peak flow rates 100year storm, with and without a 45 cm cap in the upper estuary.

Average Channel Channel Cross ­Velocities Sectional(cm/sec . ) 0*2)

Channel Number Existing With 45 cm cap. Existing With 45 cm cap. (Figure 4-3)

1 10.6 14.7 379.0 273.7 2 10.5 15.8 372.9 246.0 3 14.6 25.1 274.7 160.4 4 17.0 30.7 230.8 125.6 5 20.2 40.3 198.9 99.2 6 22.7 58.1 172.6 60.8 7 24.4 86.6 161.8 41.3 8 36.4 152.1 107.8 17.0

POTENTIAL FOR SURFICIAL SEDIMENT EROSIONDURING 100 YEAR STORM UPPER ESTUARY

RIVER FLOW RATE (SPF) 38 M3/SEC

MEAN CROSS SECTION VELOCITY 30.7-152 CM/SEC (SECTIONS 4-8)

VELOCITY REQUIRED FOR 28 CM/SEC SEDIMENT RESUSPENSION (AFTER CONSOLIDATION)

STORM FLOW VELOCITY > RESUSPENSION VELOCITY

EROSION OCCURS

SOLUTION:

• USE GRAVEL-STONE PROTECTIVE CAP IN AREA

t PLANT CORDGRASS ON LOW INTERTIDAL AREAS

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GENERAL STEPS IN CAPPING UPPER ESTUARY

t CONSTRUCT TEMPORARY DAM WITH GATES/WEIRAT COGGESHALL ST. BRIDGE USE DAM/WEIRSYSTEM TO CONTROL WATER LEVEL ANDCIRCULATION IN REGION

- DAM CLOSED AT MHW GIVES ADDED WATERDEPTH; ELIMINATES TIDAL CURRENTS

- WEIR SET AT MLW ALLOWS LIMITED TIDALCIRCULATION

• CAP UPPER ESTUARY WITH SAND FROM OFFSHOREBORROW PIT

- PLACE GEOFABRIC IN EROSIVE CAP AREA (18ACRES)

- OBTAIN CLEAN MATERIAL, SAND ORSAND/GRAVEL, FROM BURROW SITE INBUZZARDS BAY

- TRANSPORT MATERIAL TO NEW BEDFORD HARBOR(MIDDLE) BY BARGE

- HYDRAULICALLY PUMP CAP MATERIAL THROUGHPIPELINE TO DISCHARGE BARGE

- PLACE CAP MATERIAL WITH SUBMERGEDDIFFUSER IN UPPER ESTUARY. START ATNORTHERN-MOST END AND WORK SOUTH

• PLACE STONE-GRAVEL PROTECTIVE CAP

- PLACE GEOFABRIC IN EROSIVE CAP AREA (18ACRES)

- USE BARGE MOUNTED CRANE AND SCOW TOPLACE GRAVEL PROTECTIVE CAP. DAMCLOSURE AT MHW GIVES ADDED WATER DEPTHFOR OPERATION

t VEGETATE NEW INTERTIDAL MARSH AREAS

t MONITOR CAP INTEGRITY, VALIDATE CAPPERFORMANCE

t REMOVE TEMPORARY DAM

ALTERNATIVE CONSTRUCTION APPROACH (IN THE DRY)FOR HOT SPOT, PROTECTIVE STONE-GRAVEL CAP AREA

t BLOCK RIVER CHANNEL NORTH AND SOUTH OF HOT SPOT.TIMBER SHEET PILE WALL TO NORTH, LOW EARTHEN DIKESOUTH SIDE

t REROUTE RIVER FLOW BY PIPELINE AND PUMPING. PUMPENCLOSED AREA DRY

• LAY GEOFABRIC

• PLACE SAND CAP FROM LAND USING TRUCKS AND SMALLCONSTRUCTION EQUIPMENT. PLACE IN FINGER FORMATION TOAVOID MUD WAVES

t PLACE PROTECTIVE STONE-GRAVEL CAP, SAME TECHNIQUE ASFOR SAND

• REMOVE DAMS AND RETURN AREA TO NORMAL FLOW CONDITIONS

^cusnet"^v ,

SUMMARY OF SHORT TERM BIOLOGICAL IMPACTS

FEATURE WITH WEIR CONSTRICTION

REDUCED SALINITY ELIMINATE SOME MARINE SPECIES BUTESTUARINE SPECIES REMAIN

REDUCED TIDAL RANGE REDUCED SIZE OF PRESENT HIGH SALT MARSHBUT GAIN NEW MARSH ON PRESENT MUD FLATS

USAGE BY COASTAL NO CHANGEMIGRATORY FISH

USAGE BY ANADROMOUS FISH NO CHANGE

USAGE BY WILDLIFE NO CHANGE

REDUCED FLUSHING HIGHER NUTRIENT CONCENTRATION, HIGHPOLLUTANT CONCENTRATIONS, HIGHER BOD,LOWER OXYGEN

ATTRACTIVE FEATURES OFREMEDIAL ACTION PLAN

t AREA REMAINS ESSENTIALLY AS IS (SALT MARSH)

t PCB BURIED IN PLACE, NEGLIGIBLE CHANCE OFRELEASE TO ENVIRONMENT

t MINIMAL LONG TERM DISTURBANCE TO AREA

t PLAN IS SIMPLE IN CONCEPT, NO OPERATIONAL ORMAINTENANCE COSTS

t TECHNOLOGY WELL KNOWN

§ SERVES AS A PERMANENT REMEDIATION

• LONG-TERM ENVIRONMENTAL IMPACT MINIMAL

• AFFORDABLE

SUMMARY OF ASSESSMENT FOR PROPOSED REMEDIAL ACTION PLAN

PARAMETERS ASSESSMENT

DREDGING NONE IN UPPER ESTUARY, FORCAPPING FROM OFFSHORE

CAPPING 45 CM (35 CM FOR CHEMICALBARRIER, 10 CM TO PREVENTBIOTURBATION), COARSEGRAVEL-STONE PROTECTIVECAP (18 ACRES) FOR FLOODEROSION CONTROL

SYSTEM MAINTENANCE NONE

HYDRAULIC/FLOOD CONTROL HURRICANE BARRIER PROTECTSAGAINST STORM SURGE,ACCEPTABLE FOR RIVERFLOODING WITH PROTECTIVECAP

DECREASE IN PCB MIGRATION SIGNIFICANT (>95%)

ENVIRONMENTAL IMPACT WITH CAP, CREATE 30 ACRESSALT MARSH

SUMMARY OF ASSESSMENT FOR PROPOSED REMEDIAL ACTION PLAN(CONTINUED)

ECOSYSTEM EFFECTS MINOR, TEMPORARY WATER QUALITY PROBLEM DUE TO DAM/WEIR CONTROL

MITIGATION CREATE NEW MARSH (30 ACRES, WITH CAP)

POLITICAL REMAIN SALT MARSH ENVIRONMENT, LEAVE POLLUTANT WHERE IT IS, SIMPLE SOLUTION, QUICKLY EXECUTED

REGULATORY ACCEPTABILITY PROBABLY ACCEPTABLE

COST (MILLIONS) RANGE: $15 - 30