Environmental Science & Engineering - www.esemag.com - March 2004
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Landfill gas collection and utilization in a Vancouver landfill

By J. Paul Henderson,Tracy Kyle,
and Chris E. Underwood

The Vancouver Landfill is owned and operated by the City of Vancouver and is located in the southwest corner of Burns Bog in Delta, British Columbia. An active landfill gas (LFG) collection and control system has been operated at the Landfill since 1991 to prevent odours and reduce greenhouse gas emissions.

Since September 2003, a beneficial use system owned by Maxim Power Corporation has been operating at the Landfill. The company pipes LFG to CanAgro Greenhouses, and at the greenhouse burns the gas, generating 5.55 MW of electricity for sale to B.C. Hydro and 100,000 GJ/year of heat for sale to CanAgro.

The Vancouver Landfill is located approximately 20 kilometres south of the City of Vancouver. It is a municipal solid waste (MSW) landfill and is owned and operated by the City.

The Landfill has operated since 1966, and in 2003 received 450,000 tonnes of MSW. The Landfill serves over 900,000 residents and associated businesses from a catchment area including the cities of Vancouver, Delta, Richmond, White Rock, the University of B.C. Endowment Lands, and a portion of Surrey. The Landfill is part of the Greater Vancouver Regional District’s (GVRD) disposal system, consisting of two landfills and a waste to energy facility that collectively serve 2,000,000 people.

The Landfill is considered a long-term disposal facility under the 1995 GVRD Solid Waste Management Plan with a remaining capacity of approximately 18,000,000 tonnes (approximately 12 million tonnes currently in place). In September 1999 Vancouver and Delta reached an agreement that, among other things, provides an operating framework for the Landfill until 2037. The conclusion of this Agreement has allowed the City to proceed with long-term planning and capital improvements including expansions to the site’s LFG control system.

The Ministry of Water, Land and Air Protection (MOWLAP), formerly Environment, Lands and Parks, under an Operational Certificate (OC), regulates the operation of the Landfill. The OC includes provisions for controlling and recovering LFG at the Vancouver Landfill.

The City of Vancouver has operated an active landfill gas (LFG) collection and flare system at the Vancouver Landfill since 1991. The original system covered approximately 84 hectares of the site and included 190 vertical collection wells, plus a blower/flare system. The system was installed for odour control. Landfill gas is also used to heat and provide hot water for the Landfill’s administration building. Most of the 1991 system has now been decommissioned.

ABRIDGED

The Landfill is constructed by installing compacted lifts of MSW over a 3 metre thick mattress of primarily wood construction and demolition (C&D) material. The C&D mattress is installed on top of the peat to provide a working surface for heavy equipment and act as a conduit for leachate to perimeter leachate collection ditches. Leachate is pumped to a local municipal sewage treatment plant.

Refuse is deposited in 5 metre thick lifts. The active landfill area is the most eastern landfill phase, Phase 1 in Figure 1. Phase 1 will be filled to a maximum height of approximately 35 metres by 2005 or 2006. The remaining landfill phases: 3, and then 2 to 9, will be filled over the rest of the Landfill’s operating life.

2003 landfill gas system expansion In May 2001, Vancouver City Council approved the next phase of the LFG system expansion at an estimated cost of $1,750,000. This phase involves:

10 horizontal gas collection wells, each 200 metres long and 150 mm diameter) within Phase 1;
50 vertical wells, 75 mm diameter casing, 225 mm borehole, in Phase 1 and in an area of the Landfill filled originally in the 1980s and recently recontoured to promote drainage.

A horizontal gas collection system was installed in Phase 1 to allow the collection of LFG in this area prior to closure of Phase 1. Early gas collection minimizes odours, reduces greenhouse gas emissions and provides more LFG for beneficial use. Golder Associates Ltd. provided professional services for design and installation of the system.

The horizontal gas collection laterals were installed within a 2 metre thick layer of woodwaste C&D material installed on top of the third layer of MSW. Approximately three more lifts of MSW will be installed on top of the C&D material prior to achieving the full landfill height in this phase of approximately 35 metres. The C&D material will act as a gas collection layer improving the flow of gas to the horizontal pipe network, and improving drainage within the landfill. Improving drainage within the landfill will reduce the potential for flooding of the gas collection laterals. Due to the low hydraulic conductivity of compacted MSW, flooding of horizontal gas collection pipes could cause system failure.

Gas system construction occurred over the summer of 2003, and gas from the horizontal laterals will come on line as additional MSW is filled over top of the C&D material. By the end of January 2004, 3 of the 10 lateral wells were operating. The gas flow from these lines equals approximately 900 scfm, of a total approximately 2,300 scfm for the entire system.

Future gas collection potential Given that the Landfill is expected to operate for up to an additional 40 years, LFG will be generated long into the future. Maximum LFG generation is expected to occur at the time of closure of the Landfill in approximately 2040 and is expected to equal up to 6,000 scfm (Conestoga Rovers and Associates, 1999). Increased gas collection will occur incrementally as each phase of the Landfill is completed and closed.

Landfill gas beneficial use In January 2001, the City issued a request for proposals (RFP) for LFG beneficial use. The RFP outlined the City’s desire to find a partner that would finance, design, build and operate a beneficial use facility. The City received a total of 5 proposals for the project with utilization concepts including: drying sea urchin shells for fertilizer, upgrading the gas to pipeline quality for delivery to a local natural gas line, heating greenhouses, direct use in a cement kiln, and cogeneration at a neighboring greenhouse. Maxim Power Corporation (Maxim) provided the cogeneration proposal which was rated highest, and therefore City staff began negotiations.

Their proposal involved:

An investment of approximately $10,000,000 by Maxim.
Construction of compressors and condensate removal systems at the Landfill blower/flare station.
Construction of a 2.5 kilometre pipeline from the Landfill to CanAgro’s greenhouses south of the Landfill.
Construction of a power station, including 5.55 MW of generating capacity using three Cat 3532 generators (reciprocating engines).
Use of the hot water from the engines to provide 100,000 GJ per year of heat to CanAgro’s greenhouses.

In January 2003, Maxim and Vancouver signed an agreement regarding the project. The agreement has a 20-year term and Vancouver will receive approximately $400,000 per year in revenues from the project. Vancouver’s revenues will be used to offset the cost of operating the LFG collection system.

Maxim cut the ribbon for the facility on September 10, 2003. By November 2003, the system was operating at full capacity of 2,000 scfm at 50% methane. Any LFG that is not utilized by Maxim will continue to be flared until they install additional electrical generating capacity. CanAgro is also expected to install a new boiler system that will be able to directly combust residual LFG.

Maxim is selling electricity from the project to B.C. Hydro as “green power”. B.C. Hydro is paying a premium for the power as part of its initiative to meet 10% of increased demand for electricity through a variety of new green energy sources through 2010 (B.C. Hydro, 2003). Maxim has a contract with B.C. Hydro to install a 4th engine at the facility and will be producing a total of 7.4 MW of electricity by the end of 2004.

Environmental benefits Vancouver’s goals in collecting and combusting landfill gas include odour reduction, landfill gas emission reductions, and energy recovery. Landfills are potentially a significant source of greenhouse gas emissions because methane has a greenhouse gas potential of 21 times carbon dioxide. Collecting and burning LFG significantly reduces greenhouse gas emissions due to the conversion of methane to carbon dioxide. International protocols specify that carbon dioxide generated by landfills or through the combustion of LFG does not need to be counted as a greenhouse gas emission because the carbon dioxide previously stored in the plant or animal was from atmospheric sources (EPA, 2002). Therefore, the net increase in carbon dioxide is zero.

As a reference, an automobile produces approximately 5 tonnes/year of CO2 equivalents. Therefore, the net greenhouse gas emission reduction associated with LFG collection and beneficial use at the Vancouver Landfill is equal to the emissions of approximately 45,000 automobiles.

The amount of energy available from the project is equal to approximately 500,000 GJ/year or the energy requirements of 3,000 to 4,000 households.

This article is based on a paper originally presented and subsequently published in the proceedings for SWANA’s 27th Annual Landfill Gas Symposium, March 2004, San Antonio, Texas.
J. Paul Henderson, P.Eng., Tracy Kyle, P.Eng. and Chris E. Underwood, P.Eng. worked in the Transfer & Landfill Operations Branch, City of Vancouver Engineering Services, at the time they contributed to this paper.
Contact, e-mail: paul_henderson@city.vancouver.bc.ca.

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