wetlands restoration at a small arms firing range – a case
TRANSCRIPT
Wetlands Restoration at a Small Arms Firing Range – A Case StudyN. Shetty, P.E., K. Durocher, W. Doucette, R. Wyrick, & D. Klinch – ENSR
J.P. Messier – U.S. Coast Guard
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OUTLINE
– Introduction
– Extent of Impacted Soils
– Risk Assessment
– Proposed Remediation Plan
– Wetland Excavation & Restoration
– Post-Restoration Monitoring
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Introduction
– Small arms firing range operation containing14 firing lanes
– Used earthen berm as bullet backstop– Storm sewer line, currently capped, located
upgradient of the backstop conveyed storm water to wetlands
– Craney Island Creek is bound north of the wetlands
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Site Layout – SAFR, USCG, Portsmouth, VA
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Site Assessment
– Site was registered under the VDEQ Voluntary Program– Conducted Site Assessment in 2003 and 2004
• Indicated the presence of lead and copper in forested wetlands and estuarine marsh
• Sediment• Hydric Soil• Surface Water
– Performed ecological risk assessment to establish site-specific cleanup goals
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Site Plan and Sampling Location
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Extent of Impacted Soils
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Extent of Impacted Soils
– Performed wetland survey
– Used XRF to field screen surface soils before collecting laboratory soil samples
– Soil samples collected from forested & marsh wetlands at different depths
– Total lead in soil samples ranged from 12 to 6,300 mg/kg
– Total copper in soil samples ranged from 3 to 710 mg/kg
– Additional soil data collected to perform ecological risk assessment
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Extent of Impacted Soils
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Risk Assessment
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Ecological Risk Assessment – Problem Formulation
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Ecological Risk Assessment – First Tier
– Direct contact screening• Surface water compared to VA WQS• Sediment compared to ER-L and ER-M• Hydric soil compared to ER-L/ER-Ms and Eco-SSLs
– Bioavailability evaluation of sediments/hydric soils• Simultaneously extracted metals and acid volatile sulfide
SEM:AVS
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Ecological Risk Assessment – Lead
– Forested Wetland• Total Lead in Hydric Soil
All > ER-L of 46.7 mg/kg; range 110 – 6,300 mg/kg
• SEM:AVS All > 1; range 1.2 - 405
• Surface Water4:4 > chronic, 2:4 > acute WQS
– Estuarine Marsh• Total Lead in Sediment
All > ER-L of 46.7 mg/kg; range 54 – 1,600 mg/kg
• SEM:AVS2:8 > 1; range 0.04 – 1.9
• Surface WaterLess than chronic WQS
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Ecological Risk Assessment – Copper– Forested Wetland
• Total Copper in Hydric SoilRange 30 – 220 mg/kg16:18 > ER-L of 34 mg/kg;
• SEM:AVS All > 1; range 1.2 - 405
• Surface Water4:4 exceed acute WQS
– Estuarine Marsh• Total Copper in Sediment
Range 20 – 710 mg/kg 3:4 > ER-L of 34 mg/kg & ER-M of 270 mg/kg;
• SEM:AVS2:8 > 1; range 0.04 – 1.9
• Surface WaterExceed acute WQS
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Ecological Risk Assessment – Second Tier
– Development of Site-Specific Cleanup Values• Copper not as toxic and concentrations co-vary with lead – cleanup
for lead protective of copper • Human health standard of 400 mg/kg lead for
unrestricted/residential use• Food chain evaluation in forested wetland
Marsh wren most sensitive species (80 mg/kg)Removal of 400 mg/kg area yielded average exposure < 80 mg/kg
– Consideration given to bioavailability evaluation of sediments/hydric soils• Generally SEM:AVS < 1 in estuarine marsh• Human contact not major issue due to accessibility• Minimal excavation required
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Proposed Remediation Plan
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Remediation Plan
– Remedial Action: Soil excavation and Wetland Restoration
– Remediation Goals: Clean up lead and copper impacted wetlands to VDEQ Tier II SSL Residential/Unrestricted Use• Lead – 400 mg/Kg• Copper – 310 mg/Kg
– Estimated area of lead and copper impacted soils proposed for removal was 3,600 square feet
– Depth of excavation ~6 to 18 inches in forested wetlands and ~6 to 12 inches in marsh
– Estimated volume was 82 cubic yards (cy) of which 12 cy was characteristically hazardous soils for lead
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Proposed Excavation Plan
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Wetland Excavation and Restoration
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Wetland Excavation
– February 2005• Nation Wide Permit # 38 for wetland disturbance• Sediment and erosion control permit from the City of Portsmouth
– June 2005• Stormwater Management Plan and Stormwater Pollution
Prevention Plan approved by Virginia Department of Conservation– July 2005
• Land Disturbance Permit• VDEQ approval of the remediation work plan
– Late July 2005• Removed 22 tons of hazardous soils and 74 tons of non-hazardous
soils
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Wetland Excavation and Restoration Area
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Wetland Excavation
– Excavation of forested wetlands and loading of hazardous soils in to roll-offs
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Confirmation Sampling and Restoration
– Total of 17 confirmation samples collected
– Sampling grid 25’ x 25’ in forested wetlands
– Sampling 50’ along excavation boundary in marsh
– Lead below remedial goal• 2.3 to 206.6 mg/Kg
– Copper below remedial goal• 1.8 to 32.1 mg/Kg
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Wetlands Restoration
– 50 native shrubs • Silky dogwood (Cornus amomum), arrowood
(Viburnum recognitum), elderberry (Sambucus canadensis), & black willow (Salix nigra)
– Woody trees• Tree species included red maple (Acer
rubrum) and Greenash (Fraxinuspennsylvanica)
– Wetland seed mix (25 lbs/acre)
– Marsh grass plugs (Spartina spp) – 1 plug/square foot
– Pit & mound topography
August 2005
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Groundwater Investigation
– Installed two 2-inch diameter PVC shallow monitoring wells (10’ deep)
– Collected groundwater samples for analysis of lead and copper
– Lead and copper were not detected (below VRP Tier II screening levels)
Monitoring Well in Forested Wetland
Monitoring Well in Estuarine Marsh
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Post-Restoration Monitoring
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Post-Restoration Monitoring
– Three years of annual monitoring and reporting per NWP#38 requirements
– First annual monitoring performed in July/August 2006• Visual inspection • Evaluation of survivorship & plant
health• Inspection of invasive species &
treatment (Habitat)– Increase in density of vegetation
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Post-Restoration Monitoring
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Post-Restoration Monitoring
– Additional confirmation sample in marsh collected outside the excavation area in August – September, 2006
– Sediment analyzed for SEM:AVS• SEM:AVS < 1 (0.04) for both samples
– Surface water samples• Dissolved copper and lead not detected
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End Results….
– On December 11, 2006
– Received closure certification from VDEQ
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End Results…. Marsh restored
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Acknowledgement and Thanks
– Ron Holcomb, USCG ISC Portsmouth Environmental Branch Chief
– Captain Thomas Cahill, USCG ISC Portsmouth
– GMC Scott Fisher, Atlantic Area Armory Portsmouth Supervisor
– Dave Hails, Ecological Restoration
– Virginia DEQ VAP Team: Ahmet Bulbulkaya, Patricia McMurray
– ENSR Team: David Cohn, Nicole Cowand, Seth Ryan, Todd Wilson