CIWMB’s Solid Waste Information System (SWIS) number: 29-AA-0001
Site Information per
Landfill Facility Compliance Study (Task 2)
Ceased to accept waste before 1993Information Source: Owner/Operator (Nevada County)
Telephone conversation: April 19, 2004
The owner initiated a corrective action program (CAP) in 1996 due to
contamination of off-site drinking water wells. The CAP included
constructing a final cover over the landfill, which was completed in
1998. In recent years, results from analytical testing of the affected
drinking water wells have all been below the maximum concentration
limits (MCL).
As part of the continuing CAP, the owner recently constructed a new
flare and added 29 gas extraction wells at a cost of $625,000. The
system is scheduled to begin operation in April 2004.
Since the beginning of the study period (January 1, 1998), the EA has
not issued any violations or taken any enforcement actions for gas or
surface water-related issues, and there have been no groundwater, gas,
or surface water regulations that have been too difficult, costly, or
confusing to implement at this site.
A few years ago, the regional water quality control board (RWQCB) issued
a notice of violation (NOV) for leachate seeps from a cell located in an
older portion of the landfill. The owner responded by installing a
French drain system that removes additional leachate in this area. The
interviewee indicated that the existing regulations worked well during
design and implementation of this remedy.
Information Source: Central Valley Regional Water Quality Control Board
Telephone conversation: April 16, 2004
E-mail response: May 12, 2004
The site is comprised of one unlined module and two lined modules. The
unlined unit predates the Subtitle D liner construction requirements.
The owner began a CAP in 1996 in response to detections in offsite
drinking water wells. The CAP included constructing a cover over the
landfill and providing a municipal water source to the affected
residents. The last of the landfill modules was covered in 1998;
groundwater monitoring has continued.
One of the groundwater monitoring wells located between the unlined and
lined modules began showing increases in volatile organic compound (VOC)
concentrations around 1999, after the construction of the cover. The
increase in VOC concentrations grew to one order of magnitude. The
evidence suggests that the increase in VOC concentrations is related to
landfill gas (LFG) and is a function of the landfill cap increasing
pressure on gas and forcing it move laterally through the soil rather
than exiting through the top of the landfill. The offsite former
drinking water wells continue to show trace VOC concentrations.
The RWQCB requested that the owner extract LFG as an additional
corrective action measure. The owner constructed a new flare and
installed additional gas extraction wells. Baseline testing was
conducted on the new landfill gas extraction system and operation of the
new system commenced on April 20, 2004.
There have been no groundwater-related regulations that have been overly
difficult, costly, or confusing to implement at this site. To date,
there has been little discussion between the RWQCB and the owner
regarding what criteria will be used to determine the end of the
post-closure care period. For now, the owner and the RWQCB have focused
their efforts on the CAP.
Information Source: Enforcement Agency (Nevada County Department of
Environmental Health)
Voicemail message, April 26, 2004
E-mail response: May 18, 2004
The LEA concurs with the comments from the operator, the Central Valley
Regional Water Quality Control Board, and the Northern Sierra Air
Quality Management District (NSAQMD). In early 1996, the LEA expressed
concern over the detection of elevated levels of landfill gas from some
of the onsite piezometers. The operator responded appropriately to
address these concerns.
Information Source: Northern Sierra Air Quality Management District
E-mail response: April 14, 2004
Since the beginning of the study period (January 1, 1998), the NSAQMD
has not issued any notices to comply (NTC) or NOVs, and there have been
no air quality rules or regulations that have been overly difficult,
costly, or confusing to implement at this site. There have been no
additional air quality protection measures taken at this site that are
beyond the regulatory minimums.
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