New York State Department of Environmental Conservation AVM Gowanda

Posted on June 16, 2015

Location: AVM Gowanda Site

Major Components

  • Pre-Design Investigation Report
  • Engineering Design Report
  • Remedial Design

Project Description

Introduction

The AVM Gowanda Site was an equipment manufacturing site used from the early 1930’s by the Automatic Voting Machine Corporation. It is a 1.75-acre Class II Inactive Hazardous Waste Disposal Site located in the Town of Persia, near Buffalo, New York.

D&B Engineers and Architects, P.C. was retained by the New York State Department of Environmental Conservation to undertake a pre-design investigation, a comprehensive remedial design including the preparation of remedial plans, specifications and contract documents, as well as provide pre-award services for the AVM Gowanda Site.

Site Background

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  • The AVM Gowanda Site was used from the 1930’s to 1979 by the AVM Gowanda Corporation, a manufacturer of voting machines, as a metal stamping and machine shop.
  • In 1979, Gowanda Electronics purchased the property for use as a manufacturing facility for electronic components, including inductors.
  • In 1989, New York State Department of Environmental Conservation (NYSDEC) received anonymous complaints of gasoline and solvent odors within the main building at the site. Vent pipes were subsequently installed on the northwest side of the building to address the indoor odor complaints.
  • In 1994, Phase I and Phase II site investigations were completed at the Gowanda Electronics facility. The results of these studies revealed surface soil samples with elevated levels of volatile organic compounds (VOCs) at the east end of the main building along the northern property boundary. The property owner chose to excavate the surface soil to a depth of 7 feet, removing approximately 568 tons of soil for proper off-site transportation and disposal. During the completion of the excavation it was discovered that concentrations of VOCs increased with increasing depth. VOCs had apparently migrated to the groundwater.
  • The results of an Immediate Investigation Work Assignment (IIWA) issued by NYSDEC in 1995 identified a significant groundwater contaminant plume migrating from the source area northward beyond Torrance Place. The IIWA provided the basis for the site to be listed on the NYS Registry of Inactive Hazardous Waste Disposal sites as a Class 2 Site.
  • In June 1996, a groundwater extraction well, along with and an air stripper was installed to address the VOCs in the groundwater.
  • In March 2001, NYSDEC issued a Record of Decision (ROD) for the AVM Gowanda Site. In order to eliminate or mitigate the significant threat to human health and the environment caused by the disposal of hazardous waste at the AVM Gowanda Site, a remedy was selected that included undertaking a remedial design, continuing to operate the extraction well and air stripper, and installing additional extraction wells and a monitoring system.
  • D&B was issued a work assignment to provide remedial design services in 2004. The scope of work included a pre-design investigation, preparation of an engineering design report, preparation of remedial plans, specifications and contract documents, as well as providing pre-award services.

Pre-design Investigation

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Field Work

  • Phase 1 (April 2004) – collected indoor air samples and sub-slab soil vapor samples within and beneath residences located within the limits of the groundwater contamination plume identified in the RI Report.
  • Phase 2 (May 2004) – advanced soil borings and installed groundwater monitoring wells at on-site and off-site locations.
  • Phase 3 (June 2004) – collected groundwater samples from existing wells and new wells installed in May 2004.
  • Phase 4 (July 2004) – conducted a groundwater pump test at an existing off-site well to determine the influence of pumping on the shallow groundwater aquifer, as well as develop an estimate of aquifer hydraulic conductivity.
  • Phase 5 (September 2004) – collected a second round of groundwater samples and indoor air and sub-slab vapor samples within and beneath additional residences.

Base Map Development and Surveying

A base map for the site was compiled from aerial photography and an on-site ground control survey. Site features identified on the map included roads, buildings, utilities, monitoring wells, surface water bodies and topography.

Health and Safety Program

A site-specific Health and Safety Plan (HASP) was prepared in accordance with the requirements of OSHA for the work conducted for this investigation. The HASP included site-specific health and safety information and provided for worker and community protection. The HASP was submitted to NYSDEC in May 2004.

Quality Assurance/Quality Control Program

A site-specific Quality Assurance/Quality Control Plan was also developed and submitted to the NYSDEC in May 2004. The plan was designed to maximize the quality and validity of the data collected during the field investigation.

Physical Characterization of Study Area

Site geology and hydrogeology were assessed using several techniques including observation of soil characteristic during drilling, installation of groundwater monitoring wells, sieve analysis, hydraulic conductivity tests (slug tests), pump tests, groundwater sampling and measurement of water level depths to determine groundwater elevation and gradient.

Identification of Detected VOCs

Indoor air and sub-slab soil vapor samples collected in April 2004 revealed the presence of VOCs. The VOCs detected included benzene, toluene, trichloroethane, trichloroethene and xylene. Groundwater samples collected in May and June 2004 contained concentrations of VOCs in excess of NYSDEC TOGS 1.1.1, “Ambient Water Quality Standards and Guidance Values.” Chemical contaminants detected include dichloroethane, dichloroethene, trichloroethene and vinyl chloride.

Estimation of Limits of Groundwater Contaminant Plume

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Based on the results of the pre-design investigation, the estimated horizontal and vertical extent of the groundwater contaminant plume was found to be approximately consistent with the geometry of the plume as it was presented in the RI Report. The horizontal axis of the plume was determined to be oriented in a north-northwest configuration consistent with the direction of groundwater flow. The plume was approximately 1,100 feet long and approximately 500 feet wide at its widest point when considering all groundwater concentrations of trichloroethene greater than 5 ppb. A table summarizing highest VOCs detected at different monitoring wells was included in the report.

Engineering Design Report

D&B prepared an Engineering Design Report for the NYSDEC in September 2005. The report used the findings of the previously described Pre-Design Investigation along with a bench scale treatability study and capture zone modeling to design a remedial action to address the contaminated groundwater migrating from the AVM Gowanda Site.

Bench-Scale Treatability Study

Groundwater samples collected during the aquifer pump test were submitted to an environmental testing laboratory. The laboratory conducted “jar tests” based on D&B’s Scope of Work to evaluate the steps required for removal of iron and manganese prior to removal of VOCs via air stripping. Removal or sequestering of these metals prior to treatment is required to minimize the potential for fouling of the air stripper.

Capture Zone Modeling

Using the plume delineation and pump test results presented in the Pre-Design Investigation Report (D&B, 2004), capture zone modeling was performed for several groundwater extraction scenarios, specifically conceived to address the contaminated groundwater plume migrating from the AVM Gowanda Site. A simplified two-dimensional modeling analysis was performed to evaluate extraction well configurations and groundwater extraction rates. Capture zone estimates were calculated using WinFlow™, a two-dimensional, steady-state groundwater flow model. The model simulates groundwater flow in a horizontal plane using analytical functions developed by Strack (1989). Several groundwater extraction scenarios were evaluated utilizing either six, seven or nine extraction wells with individual well pumping rates of 2.5, 5, 7 and 10 gallons per minute (gpm). A nine extraction well system, whereby six wells would be pumped at 10 gpm and three wells at 5 gpm, was recommended. This design would capture the contaminated groundwater closer to the source area and reduce the potential for migration of contaminated groundwater beneath the residences on the south side of Chestnut Street.

Groundwater Treatment System

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A system to treat the contaminated groundwater extracted by the network of extraction wells described above was also recommended. The major unit operations of the system included metals treatment/removal, air stripping for VOC removal with a shallow tray stripper, and carbon adsorption of the VOCs from the exhaust gas prior to release to the atmosphere. The design report also described the controls and instrumentation required to automate the treatment process.

The groundwater in this area of the state contains significant amounts of the naturally occurring metals iron and manganese. While it is not necessary to remove or reduce the concentration of these metals in the extracted groundwater prior to discharge to the local POTW, some level of treatment is required to prevent precipitation and subsequent fouling of the trays when the water is aerated in the air stripper. After the results of the bench-scale treatability study were received, it was determined that the most cost effective method to address this concern was to add a sequestering agent that keeps the metals in solution, rather than remove the metals by chemical precipitation.

The removal of total VOCs from the extracted groundwater is achieved by air stripping. The objective of the air stripping system is to reduce total VOC concentrations in the extracted groundwater to meet the requirements of 40 CFR Part 469 and discharge criteria established by the Village of Gowanda. The air stripper is a low-profile tray stripper where the VOC-contamindated water flows down and across a series of removable trays. At the same time, fresh air is blown into the stripper, bubbling up through the small holes in the trays and transferring volatile solutes from the liquid to the vapor phase. The stripper is designed to remove 99.9% of the trichloroethene, cis-1,2 dichloroethylene, 1,1-dichloroethylene, vinyl chloride, 1,1,1 trichlorothane and 1,1-dichloroethane from the extracted groundwater.avmgowanda5

Since the air stripper does not destroy the VOCs but actually transfers them from the water to the air, an estimate of the potential air impact was calculated using the standard point source method in NYSDEC Division of Air Technical Memo DAR 1 (Air Guide 1). These calculations concluded that a stack height of over 50 feet would be required to allow for the uncontrolled emission of the exhaust gas stream without any treatment. Since a 50-foot stack in a residential neighborhood is not practical, granular activated carbon was selected for the treatment of the air stripper exhaust gas. The carbon adsorption system will remove more than 99% of the contaminants present in the air stripper exhaust gas.

The treated groundwater will be discharged to the existing Village of Gowanda sanitary sewer system. The discharge of treated groundwater from the system will be in accordance with all Village of Gowanda requirements. After preliminary conversations with the Village of Gowanda, it was determined that the sanitary sewer in this area can accept the proposed flow from both a hydraulic perspective as well as meeting the anticipated discharge characteristics.avmgowanda6

Currently, D&B is preparing plans and specifications to enable the NYSDEC to request proposals for the extraction and treatment systems.

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