dupont site and rfi review - amazon s3...storm water and wastewater analysis using clean metals...

DuPont Site and RFI Review

South River Science Team MeetingOctober 8, 2002

Discussion Items

Areas of known soil contamination

Storm water management

RFI Results

Outfall Locations and Areas of Elevated Hg in Soil

Storm Event Monitoring

June 01 storm event sampled at four outfalls

Grab samples collected after 30 minutes

Composite flow-based samples collected in 20 minute intervals over storm duration

Outfall 001 is combined ww and storm water

Clean metals protocol was not used

Analysis per EPA 245.1

Storm Event Monitoring ResultsTotal Mercury (mg/l)

CompositeGrab

<0.00020

<0.00020

<0.00020

<0.00020

2001

<0.00020Outfall 008

<0.00020Outfall 003

<0.00020Outfall 911 (011)

0.00033Outfall 901 (001)

2001

Upcoming Activities

Re-affirmation of site waste management protocols

Storm water and wastewater analysis using clean metals protocol and low-level detection

DuPont Site RFI Results

RFI Objectives

Further characterize the site geology, hydrogeology, and groundwater migration pathways

Characterize site-wide soil and groundwater quality

Evaluate current releases and potential for future releases to the South River

Regional Geologic Map

DuPont

South River

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Site Geology

Overburden Sediments - Shallow Aquifer Alluvial sand, gravel, silt, and clay overlying bedrock Up to 18 feet thick across most of the site > 60 ft thick in karst area (NE) Absent in SW Overlies weathered Waynesboro Formation

Bedrock Waynesboro Formation - highly weathered mudstone, siltstone,

argillite and phylite (very stiff, silty clay, with shale, mudstone, siltstone) over limestone and sandstone

Shady Formation - dolomite, in NE portion of the site, subsurface only - inferred from karst features

Site Geology - Cross Section Lines

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Site Geology - Cross-Section A-A’

Site Geology - Cross-Section B-B’

Karst Area

From Gathright 1977 - Geology of Waynesboro East and Waynesboro West Quadrangles Karst area believed to be associated with the Shady Formation in

sub-surfaceNot exposed in the areaKnown to be susceptible to karst weatheringPresent to the north and south of Waynesboro

Borings drilled at western toe of Blue Ridge just northeast of Waynesboro - looking for Shady FormationNo carbonate identified up to 365 ft BGSTheorized area is mature karst - most of the Carbonate

removed/collapsed or is very deep Alternate theories on the area

Brecciated zone associated with Blue Ridge thrust faulting

Site Hydrogeology

Shallow aquifer Discharges to the South River to the NW and N May discharge to karst area in NE

Deep bedrock aquifer Groundwater source for plant Discharge location unknown Not a focus of the RFI

Karst area Deep water table - shallow water table may also be present May be in communication with bedrock aquifer Unlikely to discharge to South River

GW elevation at MW-10A = 1235 ft aMSL South River elevation ~ 1270 ft a MSL (at plant)

Captured by plant production wells?

Shallow Zone Groundwater Elevations - Aug-00

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PRODUCTION WELLS

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MW-15

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MW-3MW-2

MW-1

MW-4

MW-10

MW-9

MW-8

MW-6

MW-5

SAMPLED DURING RA/RFI

WATER LEVELBE USED TO MEASUREMONITORING WELLS TO

MONITORING WELLS TO BE

WELLS TO BE SAMPLED DURINGRA/RFI.

DEEP OVERBURDEN MONITORING

MONITORING WELL AND SOILBORING LOCATION MAP

DuPont Waynesboro SiteWaynesboro, Virginia

As shown 1/23/01 4245D001 S1

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FIGUREDRAWING NO.DATE SCALE

INITIALSDESIGNED

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APPROVED(DESIGN)

APPROVED(CONSTRUCTION)

An Alliance between

Barley Mill Plaza, Building 27Wilmington, Delaware 19880-0027

Corporate Remediation Group

DuPont and The W-C Diamond Group

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BG-2

BG-4

BG-3

BG-5BG-6

BG-8 BG-7

SB5-1

SB5-2

SB5-3

SB20-1

SB20-2SB18-1

SB18-2

SB17-1

SB16-1

SB14-1

SB15-1

SB3-1

SB3-2 SB3-3

SB2-2SB2-1

SB2-3

S C A L E

200 200' 400'

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MW-7

MW-12D

MW-12

MW-11A

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MW-13

MW-10A

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Summary of RFI Sampling Activities Completed Soil Sampling

10 SWMUsSWMU 1 - Hg RecoverySWMU 4 - Incineration Area

Background sampling 86 soil samples + QA/QC VOCs, SVOCs, metals, SPLP Hg, meHg, dioxins/furans, HMD, DMF, DMAC

Groundwater Sampling 40 samples (20 Wells, 2 Rounds) + QA/QC VOCs, SVOCs, metals, meHg, HMD, DMF, DMAC

Other Activities Groundwater level measurements Aquifer slug testing

Monitoring Well and Soil Boring Locations

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Hg / meHg Results - Soil Hg

Low ppm levels throughout plant areaUp to 100 ppm in Hg Recovery Area (generally low ppm levels)Up to 300 ppm in Incineration AreaElemental Hg observed in buried burning pit accumulation layer (12 ft BGS) in

Incineration Area Good erosion control over the site - gravel or asphalt ground cover Buried burning pit is within silt and clay - isolated from alluvial aquifer

meHg Sampled soils for meHg at Hg Recovery and Incineration Areas only Detected ppt levels across the site Low ppb levels in 2 source areas 5.7 ppm at Incineration Area (associated with elemental Hg)

Hg / meHg Results - Groundwater Hg (dissolved)

Plant area - MW-A (0.5 ppb) Incineration Area - MW-11A (0.2 ppb), MW-12 (0.17 ppb) Down-gradient boundary - All dissolved results ND (MDL=0.050 ug/L) except

MW-20D (0.12 ppb, Oct. 2000)

meHg Sub-ppt levels at all but 2 locations (0.03 to 0.45 ng/l along South River) Ppt levels at 3 wells in sources areas (21.0 to 4.66 ng/l)

MeHg Results - Groundwater

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DuPont and URS Diamond An Alliance between

Corporate Remediation Group

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MW-13 Aug '00 .057 NG/L Oct '00 .078 NG/L

MW-12D Aug '00 0.14 NG/L Oct '00 0.06 NG/L

R Aug '00 0.17 NG/L Oct '00 0.01 NG/L

MW-5 Aug '00 0.023 NG/L Oct '00 0.076 NG/L

MW-4 Aug '00 ND Oct '00 ND

MW-2 Aug '00 ND Oct '00 ND

MW-20 Aug '00 0.17 NG/L Oct '00 0.26 NG/L

MW-20D Aug '00 ND Oct '00 0.23 NG/L


MW-15 Aug '00 .089 NG/L Oct '00 .45 NG/L


F Aug '00 ND Oct '00 0.083 NG/L

H' Aug '00 0.03 NG/L Oct '00 ND

MW-18 Aug '00 0.07 NG/L Oct '00 0.14 NG/L

MW-19 Aug '00 0.03 NG/L OCt '00 0.06 NG/L

H Aug '00 0.132 NG/L Oct '00 ND

MW-16 Aug '00 0.33 NG/L Oct '00 0.32 NG/L

A Aug '00 7.9 NG/L Oct '00 21.0 NG/L

MW-12 Aug '00 18.0 NG/L Oct '00 7.6 NG/L

MW-11A Aug '00 10.5 NG/L Oct '00 4.66 NG/L

RFI Groundwater Sampling Results- Methyl Mercury (NG/L)DuPont Waynesboro Plant

Legend:

ð RFI GW Sample Locations

Well ID Date Sampled Result (NG/L)

MW-13 Aug '00 .057 Oct '00 .078

0 400 800 Feet

MeHg Mass Flux to South River - Worst Case Volumetric groundwater flux (Q) to South River:

= 5.13 x 105 l/d (94 gpm) Based on length of river boundary along plant and mean aquifer

conductivity (K), gradient (i), and saturated thickness (t)

Mass Flux of meHg to South River: = 232 ug/d Based on highest concentration detected in shallow wells along the river

(0.45 ng/l; MW-15)

Predicted increase in concentration (above background) down-stream of plant after mixing: = 5.5 X 10-3 ng/l Assumes WORST CASE - lowest daily mean flow in South River

between 1953 and 1995 (17 ft3/s; Aug 8, 1966) and highest concentrationdetected along the river

Hg Mass Flux to South River - Worst Case Volumetric groundwater flux (Q) to South River:

= 5.13 x 105 l/d (94 gpm) Based on length of river boundary along plant and mean aquifer

conductivity (K), gradient (i), and saturated thickness (t)

Mass Flux of Hg to South River: = 61.6 mg/d Based on highest concentration detected in shallow wells along the river

(0.12 ng/l; MW-20D)

Predicted increase in concentration (above background) down-stream of plant after mixing: = 1.5 X 10-3 ug/l Assumes WORST CASE - lowest daily mean flow in South River

between 1953 and 1995 (17 ft3/s; Aug 8, 1966) and highest concentrationdetected along the river

Phase II RFI Objectives

Confirm nature and extent of soil and groundwater impacts mainly source areas

Further characterize groundwater flow and quality in the northeast corner of the site

Storm event surface-water discharge sampling

Initiate annual groundwater monitoring program

Conclusions Shallow overburden aquifer

Discharges to South River along plant boundary Flows off-site to the Northeast

Karst area Deep groundwater table not likely to be in communication with South

River - perched water table may also be present Depressed groundwater level suggests capture by plant production wells Needs further evaluation - flow and GW quality

MeHg Contribution to South River via shallow groundwater appears to be

negligible Sub-ppt levels detected in GW along South River Ppt concentrations localized to source areas in plant interior

dupont site and rfi review - amazon s3...storm water and wastewater analysis using clean metals...

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