Landfill Gas Control and Monitoring
Client: City of New York, General Services, New York, New York - New 800-bed Jail Complex at Rikers Island, New York
SCS was retained by the New York City Department of General Services in 1989 to provide a variety of services at Rikers Island. Rikers Island contains a prison built atop of an old landfill. SCS was called in to develop a health and safety plan for methane gas monitoring during the construction of a 800-cell jail complex. The City was housing the inmates outside and was incurring fines, so the work needed to be performed on a fast-track basis. LFG was coming through the concrete slab, creating potentially explosive conditions. SCS prepared the health and safety plan within a month. The plan was designed to: prevent fire/explosion; identify oxygen-deficient locations; identify the presence of hydrogen sulfide; lay out the procedures to be followed by construction workers and others in the area.
The next task was the design of LFG controls. SCS designed an LFG control system, assisted in negotiating construction contract change orders, provided construction monitoring, assisted in the start-up, and prepared the O&M manual.
At another site on Rikers, SCS designed an extraction well system to draw LFG found in subsurface fill away from the buildings. An extraction test program was conducted and formed the basis of the design drawings. Again, SCS assisted in procurement of construction services. Other work included construction oversight and start-up, and preparing the O&M manual.
The next task involved a soil/soil gas/ambient air sampling program at the site of the proposed Nursery Beacon infirmary and kitchen per State requirements. SCS installed soil borings, test pits and monitoring wells, and then conducted sampling and analysis.
The sixth task SCS conducted at Rikers involved a methane investigation at the site of planned sprung structures around the island to determine if methane is present near the surface.
SCS was then asked to design, on an emergency response basis, passive methane gas control systems. The systems consisted of subslab membrane, roof vents and sensors for temporary inmate housing.
Construction engineering services were provided for a LFG control system under 20 sprung structures. Specific tasks included: assisting in procuring materials; providing consulting services; developing construction details; observing the construction; coordinating with regulatory and oversight agencies; and conducting testing to assess the system's effectiveness in controlling LFG.
LANDFILL GAS ENGINEERING, CONSTRUCTION, AND O&M SERVICES
Client: Private Sanitary Landfill, Scranton, PA
SCS provided comprehensive landfill gas engineering, construction, and operation and maintenance services to a private landfill in the Scranton area. These services have included:
Design/build of an interim LFG collection and open flare system.
Design/build of a permanent enclosed flare station.
Evaluation of LFG utilization feasibility and ongoing consulting during proposal and implementation of a high-Btu processing facility for sale of gas to the gas utility through a third-party developer.
Air emissions consulting and permitting for the following:
- Three temporary candle flares
- Three enclosed flares
- Title V facility permitting including landfill, engine, quarry, and flare operations.
- RACT proposal for VOC emissions control for the existing landfill.
- Air permitting for a landfill expansion.
Stack testing for an enclosed flare.
Ongoing routine and emergency operations and maintenance for the LFG collection and flare system.
LANDFILL GAS CONTROL AND UTILIZATION
Client: Roanoke Valley Resource Authority, Roanoke, Virginia - Rutrough Road Landfill Gas Collection System
The Rutrough Road Landfill is one of two landfills owned by the Authority. Monitoring data at this closed facility indicated that subsurface migration of landfill gas (LFG) was occurring off-site. SCS performed a field investigation to establish the nature and extent of methane migration pathways, as well as the effectiveness of an existing passive LFG control system. Measures to correct the situation were assessed under a fast time frame, due to potential hazards to a nearby active highway construction site.
Tasks included design of a new LFG collection system to migrate the problem and explosion potential, design of blower/flare station compliant with new air emissions regulations, engineering support for procurement of construction contracts, construction monitoring/start-up for the installed systems, system balancing for the LFG wellfield, and follow-up monitoring to establish that subsurface migration levels were below the facility threshold levels.
LANDFILL INVESTIGATIONS AND PERMIT MODIFICATIONS
Client: Private Landfill Operator -- Landfill Investigation and Assessment Monitoring, Roxana, Illinois
SCS conducted a study for the Roxana landfill which proved LFG to be a source of VOCs in ground water. SCS also developed a Subtitle D Assessment Program and a remediation alternative that recognizes the role of LFG in VOC transfer to ground water.
Scope of Services:
Landfill gas (LFG) monitoring at the Roxana facility indicated the presence of methane gas outside of refuse at levels exceeding the Illinois regulatory limit of 2.5 percent methane. The source of this methane appeared to be LFG. Groundwater monitoring at the facility confirmed the presence of seven volatile organic compounds (VOCs), including groundwater upgradient of the site. Potential sources for these VOCs (that were attributed the landfill) included leachate and LFG. To better identify the source and extent of potential contamination, SCS initiated a field investigation and sampling program.
The SCS field investigation concluded that, in general, both leachate and LFG were potential sources of the VOCs observed in groundwater monitoring wells. In addition, the likely source of VOCs in upgradient groundwater was identified as LFG; the data suggested that no single source was responsible for all the VOC increases observed.
The continuation of the project included the development and implementation of a State-approved Assessment Monitoring Program (AMP) for the facility. Activities under this program included further groundwater and methane gas monitoring, evaluation of the data collected, and subsequent actions to take based on the data evaluation.
Based on data from the AMP, which further corroborated the contention that LFG was a source of VOCs in groundwater, SCS designed a State-approved Interim Landfill Gas Control System which has been installed at the site. The purpose of this system is to initiate remediation of apparent LFG migration and thus reduce methane levels observed outside of refuse. Furthermore, as a part of the appropriate contingency remediation, control of LFG migration by the SCS system is recognized as having the potential to reduce VOC concentrations in groundwater that are attributable to LFG migration.