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FINAL

Wetland Impacts Assessment Report

Burgess Brothers Superfund Site

Bennington and Woodford, Vermont

September 28, 2001

SDMS DocID 486539

Environmental Partners Group, Inc.

I I I I I

Wetland Impacts Assessment Report I

Burgess Brothers Superfund Site I

Bennington and Woodford, Vermont

I I

September 28, 2001

I I I I

Paul F. Gabriel, P.E., LSP Principal

yf\Mk %idU\r Mark N.White I Project Manager

I I Environmental Partners Group, Inc.

P.O. Box 730

Ii Hingham, Massachusetts 02043

(781)749-6771

I

I I

I I TABLE OF CONTENTS

I Page No.

EXECUTIVE SUMMARY I

I 1. INTRODUCTION 1

I 1.1. BACKGROUND 1

1.2. STATEMENT OF WORK REQUIREMENTS 2

1.3. REPORT OVERVIEW 2

I 2. PRE-CONSTRUCTION ASSESSMENT 4

2.1. WETLAND AREA DELINEATION 4

I 2.2. WETLAND AREA CHARACTERIZATION 5

3. SUMMARY O F CONSTRUCTION ACTIVITIES 7

I 3.1. CONSTRUCTION OVERVIEW 7

3.2. LANDFILL AREA CAP 7

I 3.3. MARSHY AREA CAP/COVER 9

3.4 SURFACE WATER MANAGEMENT 10

3.5 PERMANENT WETLAND IMPACTS 11

I 3.6 TEMPORARY WETLAND IMPACTS 12

4. WETLAND MITIGATION 13

I I FIGURES

Figure 1

I I TABLES

Table 1

Table 2

Wetland Impact Areas

Landfill Capping Materials

Marshy Area Cover Layers and Materials

I ATTACHMENTS

Attachment 1 Figure 13 of RI Report: Wetland Boundaries

I I I ENVIRONMENTAL PARTNERS GROUP

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I I EXECUTIVE SUMMARY

I I On behalf of the Burgess Brothers Steering Committee (Steering Committee),

Environmental Partners Group Inc. (Environmental Partners) has prepared this Wetlands

I Assessment Report to document the wetland impacts associated with the Remedial

Action (RA) construction activities at the Burgess Brothers Superfund Site (the Site) in

I Bennington and Woodford, Vermont. This report has been prepared in accordance with

the Statement of Work (SOW) associated with the Consent Decree (CD) between the

I Steering Committee, United States Environmental Protection Agency (EPA) and the State

of Vermont Department of Environmental Conservation (VtDEC).

I The purpose of this report is to describe the character and extent of wetlands impacted by

RA activities. In accordance with the SOW (Section VI, subsection F), this plan includes:

I 1. An evaluation and survey of all wetlands that were impacted as a result of

remedial actions to determine the amount of wetland area requiring mitigation;

I and

I 2. A plan for restoration or replication of any degraded wetland areas.

I The Site wetland areas were delineated and characterized in the Wetland Delineation

I Report prepared by O'Brien and Gere Engineers, Inc. as part of the Remedial

Investigation (RI) activities. The report information is summarized in the Remedial

I Investigation (RI) Report, dated February 1995. No additional wetland investigations or

evaluations were necessary for completing the remedial design and RA, with the

exception of surveying in the wetlands for the As-Built Drawing.

I I Several drainage ways and three wetland areas (WetlandX Wetland-2 and Wetland-3)

were delineated at the Site. The wetland areas were shown on Figure 13 of the RI Report.

Wetland-1 is a small isolated area located northeast of the landfill in theup stream portion

I ENVIRONMENTAL PARTNERS GROUP i

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I I of existing Swale 2. Wetland-1 was not impacted by the RA activity. Two additional

wetland areas were delineated within the Marshy Area, as follows:

I • Approximately 26,700 square feet (0.62 acres) in size, at the base of the landfill

I (Wetland-2); and

I • Approximately 17,900 square feet (0.41 acres), immediately east of the then existing

monitoring well access road (Wetland-3).

I I The quality of wetlands was determined through an analysis of their function and values

using the Wetland Evaluation Technique (WET) developed by the United States Corp of

I Engineers. WET evaluates the functions and values of the wetlands based on their

physical, chemical and biological characteristics.

I The areas were defined as palustrine wetlands and were saturated to the surface by

I surficial water descending from higher elevations and meandering channels. Wetlands

vegetation consisted of tree species as in the upland deciduous forest, but with more open

I canopy. Saplings, shrubs, sedges, grasses, and several fem species were in abundance.

The Wetland Delineation Report concluded that the wetland areas are not important as a

wildlife habitat and do not provide any unique services.

I RA construction activities resulted in the permanent loss of 0.64 acres of wetland areas,

as follows:

I I • Wetland-2: 26,700 square feet (0.62 acres), associated with the construction of the

cap over the landfill and Marshy Area; and

• Wetland-3: 1,000 square feet (0.02 acres), due to construction of the toe-of-slope riprap drainage swale and discharge (Outlet 2) off the cap that terminates in this

I wetland area and discharges into the Unnamed Stream.

I These areas resulted in a total permanent impact of 27,700 square feet (0.64 acres), as

anticipated during the design phase of the project. The lateral extent of these areas are

I I ENVIRONMENTAL PARTNERS GROUP

I

I I based on the As-Built Survey work conducted by MSK Engineering and Design of

Bennington, Vermont.

I In addition, excessive rains encountered at the Site also resulted in minor siltation

I impacts to the wetland area located south of the rip rapped Outlet 2. These impacts were

temporary and were mitigated by raking, shoveling and removal of sediment to within the

I limit of work area, in accordance with a mitigation plan submitted by the Steering

Committee and approved by EPA.

I In accordance with Section XVI (Reimbursement of Response Cost and Payment For

I Natural Resource Damages) of the Consent Decree (Civil Action No. 99-CV-194 ) the

Settling Defendants reimbursed the United States Department of the Interior $100,000 to

I compensate for any natural resource damages caused by the Site. That settlement was

based (in part) on a preliminary design estimate that no more than 0.70 acres of wetlands

I would be lost due to RA activities. As a result of that settlement, and confirmation by

this report that no more than 0.70 acres of wetlands were lost due to RA activities, there

I are no additional wetland mitigation or restoration requirements associated with the

remedial action.

I I I I I I I I i

ENVIRONMENTAL PARTNERS GROUP iii

I I

I I 1. INTRODUCTION

I I On behalf of the Burgess Brothers Steering Committee (Steering Committee),

Environmental Partners Group Inc. (Environmental Partners) has prepared this Wetlands

I Impact Assessment Report to document the wetland impacts associated with the

Remedial Action (RA) construction activities at the Burgess Brothers Superfund Site (the

I Site) in Bennington and Woodford, Vermont. This report has been prepared in

accordance with the Statement of Work (SOW) associated with the Consent Decree (CD)

I between the Steering Committee, United States Environmental Protection Agency (EPA)

and the State of Vermont Department of Environmental Conservation (VtDEC).

I 1.1. Background

I The Site is located in southern Vermont in the Towns of Woodford and Bennington. The

Site consists of an approximately three-acre area located in the northeastern section of a

I 60-acre parcel.

I The predominant mechanism of contaminant migration at the Site has been surface water

infiltration through a former Landfill Area and subsequent release of leachate to

I groundwater. Once in the groundwater, the contaminants followed a localized flow

pattern into a Marshy Area and toward an unnamed stream. The Landfill Area occupies

I approximately 1.4-acres and the Marshy Area occupies approximately 0.4 acres.

I The Steering Committee has undertaken RA construction activities to prevent or

I minimize potential impacts from the Landfill Area to the groundwater and surface water,

and from ecological risks associated with surface water and sediments at the Marshy

I Area. This report has been prepared to document the impact to the wetlands from the

RA.

I I ENVIRONMENTAL PARTNERS GROUP INC

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I I

1.2. Statement of Work Requirements

I I In accordance with the SOW (Section VI, subsection F), the Steering Committee is

required to submit this Wetland Impacts Assessment Report to USEPA after it has been

I concluded that construction is fully (100% complete) performed. At a minimum, the plan

shall include:

I 1. The results of any additional wetland investigations or evaluations completed

during the remedial design and remedial action;

I 2. An evaluation and survey of all wetlands that were impacted as a result of

remedial actions, to determine the amount of wetland area requiring mitigation;

I and

I 3. A plan for restoration or replication of any degraded wetland areas.

I 1.3. Report Overview

I In order to meet the SOW requirements, this report has been structured to:

I a. Describe the efforts taken to evaluate and survey the pre-construction wetland

conditions,

I b. Briefly describe the RA construction activity that had an impact on the wetlands,

I c. Address the requirements for wetland mitigation.

I I Chapter Two describes the Pre-Construction Assessment of the wetland areas prior to

commencing RA construction activity. These activities included delineation and

characterization of the pre-existing wetland areas near the Site. Chapter Three presents a

I I ENVIRONMENTAL PARTNERS GROUP INC 2.

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I I summary of the RA construction activity that had an impact on the Site wetlands.

Chapter Four addresses wetland mitigation issues.

I I I I I I I I I I I I I I I II

ENVIRONMENTAL PARTNERS GROUP INC

I I

I I 2. PRE-CONSTRUCTION ASSESSMENT

I I The Site wetland areas were delineated and characterized in the Wetland Delineation

Report prepared by O'Brien and Gere Engineers, Inc. as part of the Remedial

I Investigation (RI) activities. The report information is summarized in the Phase 1A

Remedial Investigation (RI) Report, dated January 1994.

I No additional wetland investigations or evaluations were necessary during the remedial

design and RA.

I I 2.1. Wetland Area Delineation

The presence of wetlands was evaluated through a review of Fish and Wildlife Service

I National Wetland Inventory Maps (1977) and by delineating wetland boundaries in

accordance with federal and state methodology. The delineation was conducted by

I O'Brien and Gere on January 6, 1992.

I Several drainage ways and three wetland areas (Wetland-1, Wetland-2 and Wetland-3)

I were delineated at the Site. The wetland areas are shown on Figure 13 of the RI Report

(Figure 13. Wetland Boundaries and Invertebrate Sampling Locations, dated February

I 1995), a copy of which is provided in Attachment 1 . Wetland-1 is a small isolated area

located northeast of the landfill, in the up stream portion of existing Swale 2. Wetland-1

I was not impacted by the landfill closure activity. Two additional wetland areas were

delineated within the Marsh Area. These areas included the following:

I • Wetland 2, located at the base of the landfill and estimated in the RI Report to be

I approximately 27,000 square feet in size. The actual size of this area, based on

the As-Built Drawing of the Remedial Construction, is 26,700 square feet (0.62

acres).

I I ENVIRONMENTAL PARTNERS GROUP INC

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I I • Approximately 17,900 square feet (0.41 acres), immediately east of the then

existing monitoring well access road (Wetland-3).

I Together, Wetlands 2 and 3 are 44,900 square feet (1.03 acres) in area. It was anticipated

I during the Remedial Design that a portion of Wetlands 2 and 3 would be impacted by the

Remedial Action construction activities.

I I 2.2. Wetland Area Characterization

I A Qualitative Ecological Assessment of these areas was also conducted as part of the

Phase IA RI (Section 2.10). The assessment included a description of the following:

I 1. Objectives and methods;

I 2. Cover-type analysis;

I 3. Wildlife receptor evaluation;

I 4. Wildlife habitat quality evaluation;

5. Current and Future Land Uses

I 6. Qualitative Wildlife Exposure Evaluation

I The quality of wetlands was determined through an analysis of their function and values,

I using the Wetland Evaluation Technique developed the United States Corp of Engineers.

WET evaluates the functions and values of the wetlands based on their physical, chemical

I and biological characteristics.

I In general, the areas were palustrine wetlands and saturated to the surface by surficial

water descending from higher elevations, and channels meandering through the wetlands.

I Ii

ENVIRONMENTAL PARTNERS GROUP INC 5.

I I

I I Wetlands vegetation consisted of tree species as in the upland deciduous forest, but with

I more open canopy. Saplings, shrubs, sedges, grasses, and several fem species were in

abundance. The Wetland Delineation Report concluded that the wetland areas are not

I important as a wildlife habitat and do not provide any unique services.

I I I I I I I I I I I I I I i

ENVIRONMENTAL PARTNERS GROUP INC

I I

I I 3. SUMMARY OF CONSTRUCTION ACTIVITIES

I I

This section provides a brief summary of the construction related activities associated

with the RA. A more detailed description of these activities is provided in the Final

I Remedial Construction Report, dated February 14, 2001 and prepared by Environmental

Partners Group.

3.1. Construction Overview

I I Construction activities were conducted at the Site between July 6 and October 28, 1999.

A Substantial Completion meeting was conducted on November 23, 1999 and the Final

I Construction Inspection meeting was conducted on December 14, 2000. As-Built

drawings of the construction work are provided in the Final Remedial Construction

Report.

I The construction related activities included installation of the Landfill Area and Marshy

Area caps, installation and pilot testing of the SVE/air sparging system, surface water

I management and installation of engineering (chain link fencing) and institutional

controls. Of these activities, the placement of the Landfill Area Cap and placement of

I soils over the Marshy Area resulted in impacts to 0.64 acres of wetlands, as anticipated

during the design phase of the project. The cap and cover construction is summarized

I below.

I 3.2. Landfill Area Cap

I I The RA design approved by EPA consisted of placing a low permeable composite cap

over the Landfill Area and Marshy Area. In addition to regrading the Landfill Area to the

I required slopes, the RA design specified the placement of the capping layers and

materials described in Table 1.

I Ii ENVIRONMENTAL PARTNERS GROUP INC

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I I

Table 1

I Landfill Capping Layers and Materials

I Layer

Base Layer

I I

Gas Venting Layer

I Bottom Low Hydraulic

Conductivity Layer

Top Low Hydraulic

I Conductivity Layer

Drainage Layer

I Vegetative Support Layer

I Vegetative Layer

Material

Minimum 6-inch-thick Common Fill (Intermediate Cover)

6-inch-thick Coarse Sand and Fine Gravel Stone

Geosynthetic Clay Liner (GCL)

60-mil Linear Low Density Polyethylene (LLDPE)

Triaxial Drainage Geocomposite Layer

26-inch-thick Silty Sand

6-inch-thick Loam

I In conformance with the SOW performance standards, the RA design required that the

top of the Landfill Area be graded to a minimum slope of 3% and side slopes graded to a

I maximum slope of 6:1, for slope stability. The cap design also included riprap toe-of­

slope protection around the landfill, surface water drainage controls and a passive gas

I vent system.

I In accordance with performance standard requirements, the surface water controls

consisted of the following:

I I • Riprap toe-of-slope swales located on the northern and eastern sides of the landfill

(up and side gradient diversion swales, respectively);

I 1

I ENVIRONMENTAL PARTNERS GROUP INC 8.

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I I Riprap mid-slope swales located along the eastern and southern slopes of the

landfill;

A subsurface perforated pipe, filter fabric and stone drainage system located

I along the southern edge of the landfill liner;

I " A riprap swale to convey surface water runoff from the landfill and across the

Marshy Area; and

I I • Two pre-cast concrete pipe culverts with associated riprap outlets, respectively

located in the northwest and southeast comers of the Site.

The passive gas vent system consists of two passive vents installed at least five feet into

I the landfill waste and connected to a series of 4-inch-diameter, slotted pipes.

I 3.3. Marshy Area Cap/Cover

I The RA design also conformed to the performance standards for capping and covering of

those Marshy Area soils that were identified to have ecological risk. The landfill capping

I system extends across the Marshy Area to encompass these impacted soils. The capping

system either consists of the impermeable membrane liner system described in Table 1,

I above, or the soil cover system as described in Table 2, below.

I Table 2

Marshy Area Cover Layers and Materials

I Layer

I Base Layer I

I Vegetative Layer

I I

ENVIRONMENTAL PARTNERS GROUP INC

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Material

18-inch-thick Common Fill

6-inch-thick Loam

I I

3.4 Surface Water Management

I I

In order to comply with performance standards surface water drainage controls capable

of handling a 100-year, 24-hour storm event were constructed to minimize erosion of the

I Landfill Area cap and Marshy Area Cap/Cover. These areas were also revegetated and

the vegetation will be maintained to prevent erosion.

I To limit the negative impacts that could result from excessive soil erosion during

I construction, the Contractor also prepared a Soil Erosion and Sediment Control Plan

(SESCP) in accordance with the revised Contract Drawings and Specifications. The

I SESCP was provided in the Final Remedial Construction Report, dated May 14, 2001, as

part of Appendix I - Contractor Submittals. In general, the SESCP met state and federal

I requirements for controlling soil erosion and sediment, particularly the requirements of

the State of Vermont Handbook for Soil Erosion and Sediment Control on

Construction Sites (VtDEC Handbook).

I During construction, EPA also required upgrades to the existing Hillside Diversion

Swale. This work consisted of the following:

I • Construction of earthen berms along the west side of the swale at three locations;

I I

• Placement of filter fabric and riprap over significant topographic gradients, along

the lower reaches of the swale; and

I • Construction of a filter fabric and riprap located at the lower end of the swale.

I These design and construction changes were incorporated into Appendix J of the Final

RA Design Report.

Ij

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I 1

I ENVIRONMENTAL PARTNERS GROUP INC 10.

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I I These upgrades to the existing Hillside Diversion Swale resulted in rerouting of

approximately 400 linear feet of the Swale 2, which discharged into the Marshy Area and

I landfill toe of slope area before rejoining Swale 1 west of the landfill, to its current

location away from the landfill. Relocating Swale 2 allowed the Marshy Area and

I landfill toe to be dewatered in preparation for the construction of the landfill capping

system. This swale relocation resulted in the loss of some existing aquatic habitat where

Swale 2 existed, however the Hillside Diversion Swale provides generally similar habitat I

conditions of cover, substrate, slope and length as existed at Swale 2 and therefore no net

loss of aquatic habitat is anticipated. I I 3.5 Permanent Wetland Impacts

I Wetland areas permanently impacted by the RA construction activities are shown on

I Figure 2. These impacts were unavoidable due to grading required for the installation of

the Landfill Area cap and Marshy Area cap/cover.

I RA construction activities resulted in the permanent loss of the following wetland areas:

• Wetland-2: The entire Wetland Area 2 consisting of 26,700 square feet (0.62 acres). I

The loss of this wetland area was a result of the landfill and Marshy Area

I capping/cover activities.

• Wetland-3: Approximately 1,000 square feet (0.02 acres), of this 17,900 square foot

I wetland area. This wetland area was lost due to construction of the toe-of-slope riprap drainage swale and discharge (Outlet 2) off the cap that terminates in this area

I and discharges into the Unnamed Stream.

I These areas resulted in a total permanent impact of 27,700 square feet (0.64 acres), as

anticipated during the design phase of the project. The lateral extent of these areas are

I based on the As-Built Survey work conducted by MSK Engineering and Design of

Bennington, Vermont, shown in Figure 2.

I I I 1

ENVIRONMENTAL PARTNERS GROUP INC 11.

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I I 3.6 Temporary Wetland Impacts

I Best management practices were employed to control erosion and sedimentation into

existing wetland areas during the construction period. These controls are referenced in

I the Soil Erosion and Sediment Control Plan described in Section 3.4.

I Excessive rains encountered at the Site also resulted in only one occasion where minor

I siltation impacts to the wetland area located south of the rip rapped Outlet 2 (Wetland-3)

occured. These impacts were temporary, limited to the area immediately downstream of

I Outlet 2 and were mitigated by raking, shoveling and removal of sediment to within the

limit of work area, in accordance with a mitigation plan submitted by Steering

I Committee and approved by USEPA. These mitigation measures were coordinated with

and observed by USEPA and US Fish & Wildlife Service when they were conducted. No

I permanent wetland or aquatic habitat impacts are known to have occurred from this

event, and the wetland and habitat areas appear to have recovered from this temporary

impact.

I I Since that time, there have been no known occurances of wetland impacts as a result of

the RA construction activities. Ongoing monitoring of the swales and sedimentation

I basins is being conducted by the Settling Parties in accordance with the Post-Closure

Operation and Maintenance Plan for the Site. The sedimentation basins appear to be

I effective in collecting any sediment that is being transported by the swale, and to date

these sedimentation basins have accumulated minor quantities of soil material. The

I performance history of the sedimentation basins is an indication that the construction

activities associated with the swale has stabilized, and minimal sediment transport is

anticipated in the future.

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f I I ENVIRONMENTAL PARTNERS GROUP INC 12.

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I I 4. Wetland Mitigation

I In accordance with Section XVI (Reimbursement of Response Cost and Payment For

I Natural Resource Damages) of the Consent Decree (Civil Action No. 99-CV-194) the

Settling Defendants reimbursed the United States Department of the Interior $100,000 to

I compensate for all natural resource damages caused by the Site. That settlement was

based (in part) on a preliminary design estimate that 0.70 acres of wetlands would be

I permanently lost as a result of the RA activities. As a result of that settlement, and

confirmation by this report that no more than 0.70 acres of wetlands were lost due to RA

I activities, there are no additional wetland mitigation or restoration requirements

associated with the remedial action.

I I I I I I I

I I I I I ENVIRONMENTAL PARTNERS GROUP INC 13.

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I I I I I I I I I I I I I I I I I I

Figures

I

1. 1MB AS-9ULT MAMNC B BASED OH FCLD a m E U N C CONDUCTED BY

a. BATES OMnucnoN COMPANY AND ENVMMCHTAL P « M K OWUP, AND POST- CONSmuCTMN a jmCYMO COMOUCETO »Y U K tNOMCEOlO AND DCSGN M C OF aOMHETCH. V O W H T .

RIPRAP OUTLET 1

WETLAND 2

AS-OULT CHAM UHK FENCE

UMT Of LLDPE CAP

— — - APPMMUATE OAt WNT P H LOCATION

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PARTNERS GROUP INC. HINOHAM, MASSACHUSETTS

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^WETLAND 3 AREA(0.02 ACRES)

IMPACTED REMEDIAL ACTION CONSTRUCTION

ESTIMATED WETLAND IMPACTS

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Attachment 1

Figure 13 of RI Report: Wetland Boundaries

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w ' INVERTEBRATE w SAMPLING w x LOCATION w (TYP.)

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FIX NO. FIGURE BURGESS BROTHERS SUPERFUND SITE 5271.003.50F

REMEDIAL INVESTIGATION aBRIEN&GERE E N G I N E E R S , INC, WETLAND BOUNDARIES AND DATE'

INVERTEBRATE SAMPLING LOCATIONS FEBRUARY 1995

13