Amherst Residents for Environmental Accountability (AREA)

The State of Amherst’s Old Town Landfill

The landfill cap has been neglected, causing its deterioration well below the original DEP Permit specifications. As a result, large amounts of water are infiltrating through the clay layer (cap) that was supposed to be impermeable. This generates a large amount of leachate which leaks into the groundwater and pollutes the surrounding wetlands. Urgent measures are required to prevent further deterioration of the cap.

Original DEP Approval Specifications

The DEP letter of June 25, 1985 approved the Old Landfill Closure Plan, with a 12 inch thickness of the impermeable clay layer (cap). In response to a request from the town, the DEP agreed in a letter of August 26, 1985 to allow the town to decrease the cap thickness to 8 inches to reduce costs on the following conditions:

What was Actually Installed

The 1985 Project Manual for Sanitary Landfill Closure was used by the Town as an engineering document for the contractor hired to do the work. This document states that:

This means that the landfill was never properly capped in accordance with the 1985 DEP Closure Permit specifications.

DEP Comprehensive Site Assessment Results

The DEP test report of 2007 shows (on page 5) that the clay cap has deteriorated well below the original design specifications:

This results in water infiltrating the landfill, which generates a large amount of leachate leaking into the groundwater.

The DEP Comprehensive Site Assessment report of 2010 states (on page 3) that:

This is an industrial-size pollution happening right in our Town. For comparison, the largest landfill in the world - Fresh Kills, in Staten Island, NY - leaks 1340 gallons/acre/day.

The plume resulting from the leakage flows westward and causes elevated levels of lead, mercury, arsenic, copper, iron and cyanide that exceed WQC and MassDEP GW-1 standards, as well as the SSC guidelines.

While the GW-1 standard is for the “Potential Drinking Water Source Area” and exceeding it may not presently represent a significant risk to human health, there is a trend toward increasing levels of contaminants in the environment.

A Comparison of the DEP 2010 data with the 2007 DEP report reveals a 5-fold increase in arsenic level and a 3-fold increase in mercury level in 3 years in sediment samples at the Gull Pond and Hop Brook wetlands.

The 2007 DEP report also reports lead and chromium exceeding MassDEP GW-3 standard levels in wetlands adjacent to Hop Brook Drive near the railroad.

The GW-3 standards “apply to all groundwater in the Commonwealth” and are “intended to address the adverse ecological effects that could result from discharge of oil or hazardous material to surface water” that “pose a significant risk of harm to aquatic organisms.”

How do we address the problem?

The current state of the landfill cap requires urgent attention. The cap is sagging due to differential settlement, which is supposed to be addressed by the planned regrading.

However, the problems listed above may require more than a simple regrading in order to prevent further deterioration. A more permanent solution including the installation of an additional impermeable membrane may be necessary.

Adding an additional load of thousands of tons of equipment on top of the already fragile landfill cap will only accelerate its deterioration, increase the leaching of contaminants into the groundwater, and prevent the periodic maintenance necessary to maintain the integrity of the cap.

Click here for scans of the DEP documents mentioned on this page.