Questions and Answers about the Gude Landfill

When did the Gude Landfill operate and how much waste was placed?

The currently closed Gude Landfill operated from 1964 to 1982. Approximately 4.8 million tons of waste were placed at the Gude Landfill.

What opportunities for recreational activities are available and prudent, given the site constraints and environmental protection measures that have to be maintained by the County?

While the Gude Landfill may not be suitable for ball fields and related facilities due to its topography and the expense of dealing with ongoing settlement, there are other recreational uses that could be incorporated into the site such as playgrounds and trails.

There is also the concern of potential tampering with the existing above-ground landfill gas collection system.

With appropriate screening and buffering, and the securing of the landfill gas pipe lines from tampering, some areas of the site could still be upgraded to directly benefit the community.

Does the County have a master development plan for the Gude Landfill? What are the current and/or proposed projects for the site?

No. Due to the current efforts to plan the remediation of low-level groundwater contamination and other environmental problems at the site, plans for future uses have been delayed.

The proposed remediation approach for the site will be presented in an Assessment of Corrective Measures (ACM) report due to the Maryland Department of the Environment (MDE) on January 31, 2014.

Once the remediation approach is approved by the MDE, future construction and operational requirements associated with the remediation will be better defined, and it will be easier to understand what parts of the site may be available for other uses.

What are the regulatory agencies and regulations that govern activities at the Gude Landfill?

The Environmental Protection Agency (EPA) and the Maryland Department of the Environment (MDE) administer federal and state regulations regarding the post-closure care of closed landfills.

The primary legislation governing closed landfills for the EPA is the Resource Conservation and Recovery Act (RCRA), Subtitle D. This is Title 40 of the Code of Federal Regulations, Part 258, Subpart F. This legislation was fully implemented in 1991.

The primary legislation governing closed landfills for MDE includes the Code of Maryland Regulations (COMAR), Title 26, Subtitle 04, Sections 07.21 and 07.22. Since the Gude Landfill was closed in 1982, not all of these regulations are applicable. However, MDE still has authority to require specific actions at the site for the protection of human health and the environment.

Was there an official closure order mandated by regulatory agencies for the Gude Landfill?

Yes. For background purposes, the Gude Landfill was previously known as the Central Sanitary Landfill and/or the Gude-Southlawn Central Sanitary Landfill.

Due to the exhaustion of disposal capacity at the Central Sanitary Landfill and the lack of an adequate public system of refuse disposal in Montgomery County, an Emergency Health Order was issued by the Department of Health and Mental Hygiene (DHMH) to Montgomery County. The Order directed the County to

  • immediately redesign the Central Sanitary Landfill
  • submit a permit application to DHMH to allow disposal of solid waste at the landfill through July 1, 1981.
  • obtain all necessary permits and place into operation one or more landfill sites approved by DHMH prior to the date when the existing Central Sanitary Landfill would reach its redesigned capacity.

In 1979, Refuse Disposal Permit No. 79-15-04-06A was issued to the County to revise the grades and elevations of the existing Gude-Southlawn Central Sanitary Landfill, providing capacity for waste disposal through April 1982.

Also in 1979, Refuse Disposal Permit No. 79-15-01-02A was issued for the construction and operation of the new Oaks Sanitary Landfill in Laytonsville.

On June 3, 1981, at the request of Montgomery County, DHMH modified the Emergency Health Order to defer the required date for transferring the landfill operations from the Gude-Southlawn Landfill to the Oaks Sanitary Landfill until June 1, 1982.

The Gude-Southlawn Landfill ceased operations on May 30, 1982 and was covered with two feet of soil and stabilized with vegetation. However, the cover thickness on side slopes may be less than two feet due to erosion.

Today, the site is collectively known as the Gude Landfill.

Who is responsible for the post-closure care of the Gude Landfill? What post-closure care responsibilities are performed?

The Montgomery County Department of Environmental Protection, Division of Solid Waste Services (DEP/DSWS) has long-term post-closure care responsibilities at the Gude Landfill.

These responsibilities include:

  1. management of the landfill gas generated by the natural anaerobic decomposition of waste
  2. assuring the proper drainage of precipitation off of the landfill’s soil cover system to minimize infiltration and leachate generation
  3. maintenance of the soil cover system over the trash
  4. maintenance of site access roads and mowing to assure access to DEP groundwater and landfill gas monitoring wells and landfill gas pipelines
  5. maintenance of groundwater and landfill gas monitoring wells
  6. monitoring of the landfill gas wells, groundwater wells and surface water
  7. quarterly inspections of the site under the general storm water permit to look for
    • drainage and flow issues of the soil cap, inlets, and outfalls
    • leachate seeps
    • illegal dumping
    • exposed trash
    • other problems that may occur and require corrective actions
  8. public outreach to educate neighboring communities on
    • the history and the existing conditions of the site
    • current best-management practices and regulations for managing the site
    • environmental protection concerns and initiatives
    • proposed capital improvement projects
    • other significant changes to site conditions

Any development of the site needs to incorporate the continuation of the above post-closure care activities.

Does the Gude Landfill have a bottom liner or capping system?

The Gude Landfill is a pre-regulatory era landfill with no bottom liner system and no synthetic cap system.

In other words, the Gude Landfill pre-dated all modern landfill design, construction, operation, and post-closure care regulations.

The landfill has an approximately 2-foot soil capping system, which may decrease in thickness along certain areas of the landfill side slopes over time.

How are stormwater, leachate, and landfill gas managed at the Gude Landfill?

Stormwater is managed through the maintenance of the existing soil cap, which is graded to direct runoff to grades or riprap swales, collection inlets with discharge outfalls, or to retention ponds with outfalls.

The County maintains a contract with a landfill maintenance contractor to perform repairs to the site grading.

Since the capping system is soil, a percentage of rainfall infiltrates the landfill, which produces leachate. Leachate is any water that encounters waste.  Since the Gude Landfill is a pre-regulatory era landfill, there is no leachate collection system or bottom liner system. Therefore, the leachate is released through the landfill into the groundwater by a hydraulic gradient.

The landfill gas is collected through about 50 vertical extraction wells located on the interior portion of the landfill site and 33 vertical extraction wells that were installed for supplementary migration control on the northwestern side of landfill that faces the Derwood Station South community.  The vertical wells are typically 25 to 50 feet deep, depending upon the depth of waste, and are connected through a network of horizontal, above grade pipes which are connected to a blower system.  The blower system creates a negative pressure (vacuum) on the landfill gas collection well field. This negative pressure draws the gas towards the enclosed ground stack flares where the gas is combusted and destroyed.  The County maintains a contract with an operations and maintenance contractor to make adjustments to the well field and to perform repairs to the gas collection and management system.

What are the volumes of leachate and landfill gas generated at the Gude Landfill? How long will the landfill produce leachate and landfill gas?

On average, Montgomery County receives approximately 40 inches of precipitation per year.

Assuming that 80 to 90 percent of rain is diverted off the site, the County estimates that there are over ten million gallons of leachate flowing through the landfill into the ground water below the site over an extended period of time.

We do not anticipate any change in the volume of rainfall- and site-grading-related leachate for many years into the future. However, with time, the leachate should become less concentrated as the waste in the landfill degrades, and as naturally-occurring bacteria break down the pollutants.

The current volume of landfill gas being collected is approximately 900 cubic feet per minute. This is roughly 30 to 40 percent methane on average. Some wells have 40 to 50 percent methane; these are used to fuel the gas-to-energy power plant and other wells with lower methane content, and have their gas directed to the flare system.

Landfill gas is managed through an active landfill gas collection system that includes

  • over 80 vertical gas extraction wells
  • a series of horizontal gas conveyance piping
  • two enclosed ground stack flares that collect and burn the landfill gas
  • a 0.8 MW gas-to-energy power plant

We anticipate the volume of gas to decrease slowly over time, but it will likely need to be managed on some level for another 30 to 50 years.

What are the monitoring/testing programs for leachate and landfill gas at the Gude Landfill?

There is no monitoring/testing program for leachate as the Gude Landfill does not have a leachate collection system or bottom liner.

There is a landfill gas condensate sump at the enclosed ground stack flares. It is is pumped once a month by the County’s landfill maintenance contractor and transported to the leachate pretreatment plant at the Oaks Landfill. The Oaks Landfill leachate pretreatment plant is governed by a Washington Suburban Sanitary Commission Industrial Discharge Authorization Permit, which specifies the testing and reporting requirements for the pre-treated landfill leachate.

The County’s Department of Environmental Protection (DEP) performs weekly monitoring for methane content in the seven three-level methane detection wells. These wells are located at the base of the northwestern side of the landfill. below the migration control wells adjacent to the Derwood Station South community. DEP also performs quarterly monitoring for gas at other locations along the perimeter of the site that do not have any residences nearby. Quarterly monitoring is performed in accordance with an MDE approved monitoring plan for the site.

SCS Engineers performs monthly monitoring of the landfill gas quality and maintenance on the flare station and collection well field consisting of over 80 gas extraction wells as necessary.

The current standard is that the presence of methane should not have a concentration greater than 5 percent by volume, which is the Lower Explosive Limit (LEL) of methane, beyond the landfill property boundary or at adjacent structures.

The current efforts represent best management practices for landfill gas control, and we continue to upgrade the system as required.

An analysis of the landfill gas at the Gude Landfill was performed in February 2008. The analysis characterized the following constituents by percent volume: hydrogen, oxygen, nitrogen, carbon dioxide, and methane. Hydrogen sulfide is presented in parts per million or ppm by volume. An analysis was also performed for volatile organic compounds.

Is there ground water, surface water, and landfill gas monitoring performed at the Gude Landfill? Is the historical data available for review?

The County's Department of Environmental Protection (DEP) maintains responsibility for monitoring and testing of the groundwater and surface water. DEP also performs weekly monitoring of a series of landfill gas monitoring wells. A contractor performs routine monitoring and maintenance activities related to landfill gas management.

Historical data is available for groundwater, surface water, and landfill gas monitoring. The historical data for groundwater and surface water indicates broad-based low level contamination from organic compounds. There are also some elevated metals concentrations, but these are similar to metals concentrations in the region and are likely not landfill-related. The contaminants in the ground water are representative of the contaminants in the leachate at a more diluted level.

Describe the protection measures and procedures that the County implements to protect residents from leachate, landfill gas, and groundwater and surface water contamination.

With respect to leachate, the County does annual maintenance on swales, pipes, and drains. It also performs site grading to properly manage stormwater and achieve diversion of most stormwater off the site, thus reducing infiltration.  There is no feasible way of collecting the leachate; however, we try to minimize its formation by properly managing stormwater.  

The County has developed and installed an extensive landfill gas collection and management system to minimize environmental releases of landfill gas and control migration of landfill gas towards the adjacent community.  The County has a long-term landfill gas system maintenance contract in place to assure that the gas collection and management system is properly maintained to achieve the desired level of gas collection and control.

In 2005, methane detectors with audible alarms were offered to residents in homes backing up to the landfill.  Approximately a dozen homeowners requested the alarms, which were installed and have been in place since that time.  The detectors were added or replaced in 2013 in all the Derwood Station south homes that requested them that are adjacent to the Landfill property boundary.

The monitoring of groundwater and surface water performed by DEP provides documentation of existing conditions for the Gude Landfill site. Given that all adjacent homes and businesses are on public water, the presence of leachate in groundwater poses no health hazard with respect to the drinking water supply.  There have also been County-wide efforts to encourage vegetative stream buffers and to develop better stormwater quality and quantity control structures to protect surface water quality.

Does the County plan to take measurements for fugitive emissions not collected by the landfill gas collection system from the landfill surface?

Since the Gude Landfill is a pre-regulatory era landfill with no synthetic cap system, it has the potential to release fugitive landfill gas emissions (that are not captured by the active landfill gas collection system) through the soil cap that results from the natural decomposition of waste. This is a known problem with landfills from this era.

While the current landfill gas collection and management system follows best management practices for retrofitting older landfills, the County implemented a landfill gas surface scan during the week of November 24, 2008. This scan monitored ground level emissions from the landfill through the soil cap to estimate fugitive emissions from the landfill.

The tentative determination from the surface scan was that no significant quantities of methane were detected at the ground surface level over the approximately 100-acre site. DEP/DSWS received the final surface scan report and no significant levels of methane were detected. The surface scan was performed in accordance with Code of Federal Regulations (CFR): 40 CFR 60.755.c and 40 CFR 60, Appendix A, Method 21.

What will happen in the future at the Gude Landfill site?

DEP is currently working with a consultant to prepare an Assessment of Corrective Measures (ACM) report. This report will evaluate a range of options for remediating low level groundwater contamination at the site. It is due to the Maryland Department of the Environment on January 31, 2014.

Options include

  • bioremediation
  • waste mining
  • on-site treatment of groundwater
  • cover improvements, and
  • various combinations of the above.

Once MDE approves a corrective measure, it will be implemented in the upcoming years. Differing technologies require different levels of site disturbance, although in most cases, performing remediation at the site does not preclude opening parts of the site for other uses.