CIWMB’s Solid Waste Information System (SWIS) number: 39-AA-0005
Site Information per
Landfill Facility Compliance Study (Task 2)Information Source: Owner/Operator—San Joaquin County Solid Waste
Division
Telephone interview, April 8, 2004
E-mail response: April 27, 2004 and May 19, 2004
The site is in corrective action for volatile organic compounds (VOC) in
groundwater in one well (MW-5). Some inorganics (increasing nitrates and
low pH) are contained in a separate well (MW-4). As part of the
corrective action program, the site has been closed per Title 27 of the
California Code of Regulations (27 CCR). A landfill gas (LFG) collection
system was installed in May 2001 both as corrective action against VOC
detections and combustible gas detections at the migration monitoring
perimeter. VOC detections in the impacted well have been declining since
operation of the LFG system began.
Additional wells where VOCs have been sporadically detected in trace
amounts have also shown declining detections (fewer traces). However,
the inorganics detected in MW-4 have not shown these reductions. The
owner recently conducted a study to investigate whether nitrates came
from a nearby creek used by cattle, but the results were inconclusive.
The site received violations from the enforcement agency (EA) for
methane concentrations in excess of 5 percent at the monitoring
location. Most perimeter probes were brought within regulatory limits
shortly after operation of the LFG system began. Currently, all of the
gas monitoring wells indicate compliance with LFG migration monitoring
standards.
As a proactive measure, the owner improved a drainage ditch that empties
into a retention pond, resulting in an improvement in environmental
protection of the site.
In addition, the owner has found that the final cover of the landfill
should be a minimum 10 percent slope to accommodate future settlement,
thereby reducing ponding and minimizing the need for regrading.
The owner received a violation at the site after installing the landfill
gas system due to failure of the source test for the flare to provide
the required destruction of VOCs. The flare has since been fixed,
retested, and has passed.
The site is inactive, so no dust is created by earth moving activities
(there are none). Little dust is created by the infrequent maintenance
visits.
There is one air regulation that has proven difficult. The site is
constrained to 144 hours of scheduled downtime for maintenance of the
landfill gas collection system, but there is no allowance for downtime
for unforeseen difficulties such as an electrical grid failure. A
suggested revision to the permit would include the allowance for the
assignment of scheduled maintenance downtime to unscheduled downtime due
to mechanical or electrical power grid failure.
Information Source: Central Valley Regional Water Quality Control Board
Telephone interview: April 6, 2004
The site is an unlined landfill and was closed in 1995 with a
prescriptive cap. The site is in Corrective Action due to the presence
of VOCs in groundwater. The corrective action for the site included
closure and groundwater monitoring.
Title 27 regulations require monitoring the entire site for groundwater
impacts. The Owner has recently drilled several new wells, because some
of the existing wells went dry and were not suitable for monitoring
groundwater. The owner is currently investigating leachate impacts, as
well as VOCs, because some nitrates have been detected. It is unclear
whether these detections are caused by the landfill or if they come from
a nearby creek used by cattle.
In addition to these activities, the owner has implemented a gas
collection system and is burning off the VOCs. The site has met all of
the prescriptive minimum requirements for an unlined landfill, and the
owner is doing everything possible to address the problems.
The RWQCB expressed concern over the need to drill very deep wells to
encounter the first groundwater (at some sites, up to 500 feet, which is
very costly). As suggested by guidance documents for leachate
attenuation, the likelihood of leachate impacts to groundwater at such
sites is practically non-existent (although pressure gradients may force
gas to this depth).
Information Source: Enforcement Agency—San Joaquin County Environmental
Health Department
E-mail response: March 25, 2004
The site closed in 1995 and was first cited for an area of concern (AOC)
in December 1996 for methane levels greater than 5 percent at the
boundary. The owner stated that the site was remote and that there were
no off-site structures within 1,000 feet of the site in any direction.
Methane continued to be above the 5 percent level in several gas wells.
There were several meetings and letters directing the owner to take
action. In April 2001, prior to issuance of a notice and order, the
owner installed a gas collection system and flare. Methane detections
above 5 percent continued at the boundary, although the gas monitoring
wells were trending lower and some wells cleared up altogether. The last
gas well dropped below 5 percent in December 2002 and the owner has been
able maintain levels below 5 percent at the boundary since that time.
Existing landfill gas regulations allow gas issues to be mitigated
appropriately. These mitigation measures are necessary, considering that
most VOC plumes associated with landfill sites are caused by landfill
gas. Experience at this site has shown that landfill gas can move
around. It may be generated long distances away and be carried to a gas
probe through fissures and porous soil strata. Achieving gas control
requires a lot of attention (for example, proper maintenance and
clearing condensate blockages quickly). The EA believes that the
regulations should require installation of multi-nested gas monitoring
probes during landfill construction as facilities start generating gas
shortly after the waste is covered, to curtail the potential for
landfill gas-related impacts to groundwater such as those seen at this
site.
In relation to surface water and leachate control issues, the site has
not had many problems even though Corral Hollow does not have a leachate
collection system. There were some drainage and erosion issues
immediately after closure, but not since then. The site is equipped with
the regulatory minimums and is working well.
Information Source: San Joaquin Valley Air Pollution Control District
E-mail response: April 6, 2004
Landfills must comply with the San Joaquin Valley Air Polluction Control
District’s (SJVAPCD) Regulation VIII (Fugitive Dust Prohibitions). For
example, travel on unpaved roads results (1) in dust being entrained
into the air or (2) carry out/track out of dirt onto paved public roads,
which is then pulverized and entrained into the air by vehicles in the
form of dust. Landfills must comply with Regulation VIII when new cells
are excavated and prior to commencement of landfilling activities.
However, the spreading of landfill daily cover is exempt.
The SJVAPCD allows a variety of control methods to minimize/prevent/or
clean up fugitive dust sources. For example, owners may use water,
washed gravel, chemical/organic dust suppressants, and road mix (oil and
sand) to control dust, or pave unpaved roads. The landfill owner is free
to select any control technique that is effective for that particular
site.
According to the SJVAPCD, the district takes great care to ensure that
its regulations do not place unnecessary burdens on other public benefit
agencies. In addition, the district’s Regulation VIII (Fugitive Dust
Prohibitions) contains exemptions if CIWMB regulations/requirements
might be affected.
The SJVAPCD stated that there have been no air quality related issues at
this site since the beginning of the study period (January 1, 1998), and
there have been no problems implementing the existing landfill
environmental protection regulations at the site..
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