Newsletter

June 2001

Cleaning up A Hazardous Waste Site under the “Limited Project” Provision of the Wetland Protection Act Regulations

By: Bonnie Potocki, Eco-Solutions and Carol de Groot Bois, L.S.P.

Introduction
On October 1, 1993, the Massachusetts Department of Environmental Protection (MADEP) issued significant revisions to the regulations governing cleanups of oil and/or hazardous materials (OHM) – the Massachusetts Contingency Plan, or MCP (310 CMR 40.0000). The redesigned program was intended to expedite the investigation and remediation of hazardous waste sites across the state, primarily in two ways. First, the program allowed “privatization” of the work, with the majority of sites being managed under the guidance of “Licensed Site Professionals (LSPs)” and secondly, focussing the DEP’s role in overseeing work where it was most needed, at sites where private parties could not (or would not) handle the necessary response actions.

In addition, the Department also later modified portions of the Massachusetts Wetland Protection Act (WPA) and its regulations (310 CMR 10.00), to allow for both emergency and non-emergency actions under the MCP that might impact resource areas protected under the WPA. The basic wetland performance standards for MCP projects are:

  • If feasible, avoid wetland alterations; and
  • If not feasible to avoid wetland alterations, then minimize adverse wetland impacts and mitigate any adverse impacts that could occur.

An example of the changes to the WPA Regulations include the wetlands " limited project" standard for non-emergency OHM release response actions that are necessary to protect health, safety, public welfare, and/or the environment, but that cannot meet current wetland regulatory standards without obtaining a variance. This article describes a case study where the remedial action at a disposal “Site” was designed, constructed, and implemented to avoid or minimize impacts to a nearby perennial stream, Mill Brook.

Site Description
The Site is in downtown Wakefield, Massachusetts. The property is a triangular-shaped parcel, approximately 0.5 acres in size. Figure XXX shows the Site layout. The Site is in a commercial/industrial part of Wakefield. The Site is flat, with an office building located on the property and a parking area. A drainage swale was located on the west side of the property.

The primary compound of concern at the Site was lead in the surface soil, which was determined to be located from the surface to a depth of approximately six feet below grade in fill material across the Site. The MCP Phase II Field Work delineated the elevated concentrations of lead in the soil as being restricted to the top six feet of the fill material, since soil samples from the peat layer beneath the fill, collected at depths between 6 and 12 feet below grade, had lead concentrations less than 54 mg/Kg. In addition, lead was also detected at elevated concentrations (up to 16,000 mg/Kg) in the sediment from the drainage swale on the west side of the property.

Drainage Swale and Mill Brook
A vegetated drainage swale was located on the west side of the Site. The swale received runoff from the unpaved parking lot of the Site (to the east) and off-site to the west from a paved parking lot that serves an adjacent shopping plaza. The dimensions of the swale were approximately 230 feet in length and five feet in width. The swale also received flow from upstream of the property, to the south. The swale originated at Crystal Lake Reservoir approximately 570 feet south of the property. The origin of the swale is an overflow weir from Crystal Lake. From Crystal Lake, the swale’s channel is open for approximately 200 feet, and then enters an enclosed culvert that runs underneath a road for approximately 300 feet until it reaches the Site. The flow from the culvert entered the Site’s open drainage swale. Before the remedial actions were undertaken at the Site, the Site’s swale converged with Mill Brook, a perennial stream, which flowed into a culvert under a road at the northern end of the Site. Mill Brook is culverted for approximately one-half mile and then discharges to the Mill River further northeast of the property in Wakefield.

The Site’s drainage swale was considered an intermittent stream based on information provided by the Town of Wakefield Department of Public Works and observations made during a Site inspection. Wetland plants grew along the banks of the swale and in the channel. They included purple loosestrife (Lythrum salicaria) and a small clump of cattails (Typha sp.). Given the nature of the drainage swale’s juxtaposition to developed land and the weedy dominant species, its resource value was considered minimal.

During a storm in October 1996, the dam at Crystal Lake was damaged and therefore, a continual flow of water from the lake had been entering the overflow weir that discharged to the Site’s drainage swale. The dam was originally built to increase flood storage capacity during storm events and the overflow weir was not designed to allow continual flow from the lake. The increased volume of water from lake changed the physical conditions within the unlined swale on the Site. The flow in the swale had become continuous; therefore, the swale remained wet throughout the year. Prior to the October 1996 storm, the channel was dry some portions of the year and flow was intermittent. Neither the swale nor Mill Brook was evident on the U.S.G.S. Map for the area.

As part of a grant from the Federal Emergency Management Agency (FEMA), the Town of Wakefield Department of Public Works was provided with funds to repair the dam and the overflow weir to its original condition. Therefore, the DPW was examining ways to enclose the drainage swale as part of the flood control/repair program. The lead concentrations, however, posed a concern to the Town. Therefore, the property owner, in conjunction with the LSP on the project, determined that enclosing the swale could be included as part of the remediation program for the Site.

In addition, because of the flood control repair to the overflow weir, it was anticipated that continual flow from the dam would eventually cease. As a result of the Town’s flood control repair project, the water in the swale would have dramatically decreased and channel would become dry. The wetland plants would be impacted because of decreased water input.

Determination of Resource Areas
The following areas were determined to be resources areas defined by Wetlands Protection Regulations (310 CMR 10.00) for this project:

Resource Areas

  • Land Under Water Bodies/Waterways – Mill Brook
  • Banks – Banks Mill Brook and Intermittent Drainage Swale Bordering Land Subject to Flooding – area between BVW or Bank and 100-year flood limit
  • Riverfront Areas – 0 to100 feet and 100 to 200 feet areas from the top of bank of Mill Brook
  • Buffer Zone – 100 feet from top of bank of drainage swale and BVW or bank of Mill Brook

Nature and Extent of Contamination
The results of the Phase II Field Work indicated that the compound of concern was lead in surface soil at the Site, and in the drainage swale's sediment. Concentrations of lead in shallow sediment from the drainage swale ranged from 1,000 mg/Kg to 16,000 mg/Kg. Upstream sediment samples in the drainage swale and downstream sediment samples had lower concentrations of lead. The sediments from the Site’s drainage swale did not appear to have affected downstream sediments in the Mill River. Based on surface water sampling, the lead in the sediment had not degraded the water quality in the swale. Based on past groundwater sampling, the lead in groundwater at the Site is below the most stringent (GW-1) groundwater cleanup standard.

The presence of lead in the surface soil on the Site and sediment was likely the result of deposition in the past from the operations of the former Lead Lined Iron Pipe Company on the abutting property (the shopping plaza) to the west. In addition, lead deposition may have occurred in soil and sediment when the Lead Lined Iron Pipe Company operated a storage facility at the Site, in the 1930’s to sometime prior to 1966.

Conclusions of Phase II Risk Characterization
The MCP requires that the potential health and environmental risks posed by compounds at a Site be evaluated to determine if remediation is warranted. Therefore, a human health and environmental Risk Characterization were performed. The environmental Risk Characterization concluded that a potential existed for risk of harm to aquatic receptors exposed to sediment in the drainage swale. The Risk Characterization determined that the conditions at the Site posed a Significant Risk of harm to health, safety, public welfare, and the environment. Therefore, evaluation and identification of possible Comprehensive Response Actions (CRA) was required under Phase III of the MCP regulations.

Phase III of the MCP results in a “Remedial Action Plan” after evaluation of feasible remedial technologies. The remedy selected is the result of evaluating several alternatives that includes consideration of wetland impacts. Possible options of remediation were evaluated to determine the appropriate remediation to reach Site closure. On-site capping of the soil and sediment, as well as enclosing the drainage swale in a culvert, were selected as the most feasible alternative. This remediation option also included an Activity and Use Limitation (AUL) to be placed on the deed to the property in order to maintain the cap and prevent direct contact with the lead in the soil for the “foreseeable future,” as required by the MCP. Since the remediation work would be conducted in resource areas under the Wetlands Protection Act, a Notice of Intent was filed with the local Conservation Commission before the remediation project began.

Activities Subject to Regulation and Compliance with Performance Standards
The selected remedial action fell under the “ limited project” provisions of the Wetland Protection Regulations for Response Actions to Releases of Oil and/or Hazardous Materials. The regulations cover both coastal resource area work at 10.24(7)(c) (6), and inland resource area work at 10.53(3)(q). The MCP remedial action was a "Comprehensive Remedial Action" in an inland area and therefore was regulated by 310 CMR 10.53 (3)(q) of the Massachusetts Wetland Regulations.

Analysis of Comprehensive Remedial Alternatives in accordance with 310 CMR 40.0851 to 40.0869

Bois Consulting Company prepared a Phase III Remediation Action Plan as required by the MCP. The purpose of the Phase III Remedial Action Plan was to identify, evaluate, and select an appropriate remedial action alternative that is likely to be a Permanent Solution. The Phase III Report is also referred to as the “Phase III Feasibility Study.” By definition, if an MCP remedial action is selected in conformance with the Phase III requirements of the MCP, then it meets the alternatives analysis required in the “limited project” provisions of the Wetlands Protection regulations.

The alternative that would not alter the resource areas associated with the drainage swale and Mill Brook was the "No Action" alternative and provided a baseline for evaluating other alternatives in terms of damage to the most important resource area, Mill Brook. Several treatment technologies or alternatives were selected and evaluated to determine the technology that was expected to treat the lead-contaminated sediment in the channel of the intermittent stream that discharges into Mill Brook. These alternatives are listed below.

Treatment Technologies

  • No action: Also known as natural attenuation, this option relies on the natural processes existing at most sites to retard the migration of the contaminants. Although metal concentrations will not decrease with time, the mobility and toxicity of metals can decrease as the site conditions mature. These processes assist in reducing the risk at the site, but would not eliminate the potential for direct contact with the lead in the soil or the sediment at the Site.
  • Excavation and offsite disposal: This process is the physical removal of contaminated soil for recycling, treatment, or disposal at a regulated offsite treatment facility. This option would also involve removal and treatment of the groundwater for suspended solids during the soil excavation.
  • In Situ Soil Stabilization: By introducing a reagent into the ground and mixing the soil in place, the mobility of the lead is reduced, thus reducing the overall risk.
  • Ex Situ Soil Stabilization: This technology is similar to in situ soil stabilization, but the soil is excavated and the reagent mixed with the soil aboveground. The soil is then commonly reused onsite.
  • Capping: A specially designed cap is placed over the soil to reduce the amount of water that infiltrates into the soil and thus reduces the amount of water that might potentially leach lead from the soil.

The "comprehensive remedial action alternative" was selected in accordance with the MCP (including 310 CMR 40.0851 to 40.0869). The remedial technologies noted above were evaluated based on the following criteria:

  • Long-Term Risk Reduction
  • Short-Term Risk
  • Certainty of Meeting Goals

In addition, the MCP requires an evaluation of the feasibility of each alternative. Some of the factors involved in evaluating the feasibility of an alternative are:

  • The alternative is not technologically feasible (an unproven technology, for example);
  • The costs of conducting, or the risks resulting from the alternative, are not justified by the benefits, considering potential damage to human health or the environment, the cost of environmental restoration, long term operation and maintenance costs; and
  • The alternative would require land disposal other than at the site itself and no off-site facility is available.

Based on a comparison of the alternatives, the recommended remedial alternative for the Site was capping the soils and sediments and enclosing the drainage swale in a culvert. A properly designed and maintained cap would prevent exposure to the lead. The cap was to be designed as an “engineered barrier” under the MCP. The cap included a geotextile filter fabric, gravel, and a layer of base course of asphalt under the paving for the parking lot. This cap, combined with an AUL to prevent future excavation and off-site removal of the soil unless a soil management plan is implemented, would eliminate the risk posed by the lead in the surface soil and sediment. This technology resulted in a health-protective, environmentally acceptable, cost-effective solution that resulted in eliminating or minimizing health and environmental risks and remediating the site in a timely manner. There were no feasible alternatives to the response action that would be less damaging to the Mill Brook that would also reduce the risk as required by the MCP.

This alternative would eliminate the potential for exposure to the sediments in the drainage swale and would eliminate the potential migration of sediment downstream in Mill Brook, the valuable downstream resource area. During the installation of the culvert, purple loosestrife and its seeds would be removed with the soil. This action also would prevent the transport of viable purple loosestrife seeds further downstream to Mill Brook.

Compliance with 310 CMR 10.53(3)(q) of Massachusetts Wetland Regulations

The selected remedial action was designed, constructed, and implemented to avoid or, where avoidance was not practicable, to minimize impacts to Mill Brook. Capping of the swale and surrounding surface soil was planned to minimize or eliminate the migration of lead in the sediment of the drainage swale into Mill Brook. The project was initiated in October 2000 and completed in November 2000 after receiving an approved Order of Conditions from the local Conservation Commission, and after the appropriate MCP documents were prepared and submitted to the DEP.

In accordance with 310 CMR 10.53 (3)(q)(2), limited projects must be selected using an alternatives analysis in the MCP Phase III, and must meet the following standards to the maximum extent practicable:

a. Minimizing hydrologic changes: Hydrological changes to the Mill Brook were minimized during the construction by placing a temporary checkdam to prevent downstream sediment migration. The flow from upstream of the drainage swale was routed around the culvert area and discharged to Mill Brook. Hay bales were placed around the construction and excavation area to prevent or minimize surface runoff.

b. Using best management practices to prevent erosion and siltation: Best management practices included the checkdam, constructed of hay bales, and the hay bales around the construction and excavation areas. In addition, the Notice of Intent required additional hay bales to be available and installed in the event of any erosion problems that might arise on the Site during the project. Also, the Notice of Intent required scheduling the project to avoid high water and moving the grading and construction portion uninterrupted to completion, to avoid erosion or siltation of the wetland areas.

c. Implementing “mitigating measures”: Mitigating measures included the use of hay bales and implementing the activities described above.

d. Providing compensatory storage for all flood storage that is lost: Due to the installation of a culvert, compensatory storage was not necessary because the watercourse was planned to receive less water input from upstream Crystal Lake in the future. The project was not within the flood plain, according to Flood Insurance Rate Map for the Town of Wakefield.

e. Examining the potential for increasing flood stage by restricting flow: The installation of the new culvert would not increase the flood stage or flow velocity of Mill Brook because water input from Crystal Lake would be dramatically decreased. In addition, the culvert at the northern edge of the property already limited the flow. The Town was also installing a new bar grate at this culvert to prevent or minimize further flooding.

f. Placing temporary structures and work areas in resource areas/reestablishing vegetation: Temporary structures and work areas in the Mill Brook were removed within 30 days of completion of the work. Temporary alterations to the Mill Brook were restored to pre-existing hydrology and topography. The banks of Mill Brook were not affected by the placement of the culvert. At the local Conservation Commission’s request, the area above the culvert will remain unpaved and be revegetated.

g. Working on frozen, dry, or stable ground: Work on the banks of Mill Brook occurred primarily when the ground was dry or otherwise stable to support the equipment being used.

These requirements were made to the extent practicable during the course of the project. Sampling of the surface water during the project, both in the swale and downstream of the checkdam initially indicated some elevated lead concentrations in the surface water during the remediation activities. Upon additional sampling, however, it was determined that the concentrations were associated with suspended sediment, and no adverse effects were observed in the downstream surface water samples after the remediation was completed (within approximately 30 days).

Conclusions
In conclusion, this project addressed both the requirements of two state regulatory programs, the MCP regulations and the Wetlands Protection Act regulations, using the wetlands " limited project" provisions of the WPA for non-emergency OHM release response actions. The remedial action at a disposal “Site” was designed, constructed, and implemented to avoid or minimize impacts to a nearby perennial stream, Mill Brook. The local Conservation Commission, while mindful of the need to protect a resource area, also had to balance the resource area needs with the need to protect human health and the environment under the MCP. The ultimate solution for the Site resolved both issues in a manner that was protective of human health and the environment.

Comment on this Article

>> Go to Top

<< Back to Newsletter

 


(c) AMWS 2003