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CIWMB’s Solid Waste Information System (SWIS) number: 37-AA-0022
Site Information per
Landfill Facility Compliance Study (Task 2)
Closed before 1993
Information Source: Owner/Operator: City of San Diego
Telephone conversation: March 30, 2004
E-mail response: April 13, 2004
The site was active from 1952 to 1981. The site was closed with a 2-foot
thick soil cover (which had no hydraulic conductivity requirement, in
accordance with the regulations at that time). Groundwater impacts at the site include the detection of volatile
organic compounds (VOC) in a few of the down-gradient wells. The
original groundwater monitoring system consisted of two background and
five down-gradient wells. One additional well was installed
down-gradient to further delineate the impact. The wells are monitoring
twice a year. An extended suite of VOCs is analyzed in the down-gradient
wells that have experienced impacts. An evaluation monitoring program report has recently been submitted to
the regional water quality control board (RWQCB) for review. Resolution
has not been reached regarding measures for improving groundwater
conditions at the site (in other words, no corrective action has been
selected or implemented). The causes for impacts to groundwater at this
site have been attributed primarily to landfill gas (LFG) migration
rather than leachate impacts. However, the impacts to groundwater might
also be attributed to artificial recharge from a nearby recreational
lake, which has caused higher groundwater levels in the vicinity of the
site. This lake was developed in the early 1900s with the construction
of a dam. The comprehensive LFG monitoring and collection system that was
installed in 1993 has been one measure for addressing the groundwater
impacts. In addition, groundwater impacts have been addressed over the
last 10 years through remedial grading of the site and the
implementation of best management practices (BMP) for surface water
runoff (down-drains, etc.). These measures have resulted in decreasing
trends in VOC levels in some wells, but increasing trends have been
detected in other wells. No problems have been identified in complying with regulatory
requirements for groundwater monitoring. However, the interviewee
indicated that some confusion has been experienced with regard to
defining background chemistry when groundwater is being affected by an
up-gradient source like a recreational lake. The comprehensive LFG monitoring and collection system was installed in
1993. Before 1993, only the west side of the landfill was monitored for
gas migration. The comprehensive system was likely installed as a
response to requirements of San Diego Air Pollution Control District (APCD)
Rule 59 (Control of Waste Disposal Site Emissions, 1987). An LFG conversion facility has been in the planning stages for years,
but has not yet been implemented. LFG extracted from the landfill is
currently burned in a flare. Recent improvements to the comprehensive
LFG monitoring and collection system that was installed in 1993 have
included installation of a better condensate handling system and
additional extraction wells. Fifteen additional wells were installed in
2000, distributed across the site. Three additional wells were installed
in 2001 to address migration from specific areas. Less off-site
migration has occurred as a result of system improvements. The
interviewee also indicated that additional improvement of LFG control
may be attributed to the implementation of BMPs for surface water
control. Homes have been constructed up to the property boundary on the west
side, a portion of the south side, and a portion of the east side of the
landfill. The waste unit abuts the property boundary on the west side
and a portion of the south side. On the east side, there is a small
buffer between the waste unit and the property boundary. LFG has been
detected in the probes where the waste abuts the property boundary, but
not exclusively. The violations issued by the EA in a response to the
detections suggest that the landfill has had difficulty complying with
the current regulations, but there has been no particular difficulty
interpreting them. The site has had no leachate control problems for the last few years.
The site used to get seeps, but the slopes were regraded and mulched and
leachate control has not been a problem since. The interviewee indicated that it can be difficult on a site as large as
this one (120 acres) to consistently comply with some post-closure care
regulations. For example, the requirement for preventing ponding
(section 20650 of Title 27 of the California Code of Regulations) is
left open to the interpretation of the regulator so that a small
depression, such as a rut from a tire, may be considered a “pond” and
would require maintenance to repair. Silt control has also been
particularly difficult to address on this large site. However, the
implementation of surface water control structures and BMPs have helped
control silt deposits. They have employed the following techniques at
this site: grading, paved channels, rock check structures, and mulching. The APCD permit is held by the owner for the gas collection system.
Within the past few years, an operator was hired to maintain the gas
collection system, but the permit is still held by the city. Two notices of violation (NOV) have been issued by the APCD since the
beginning of the study period (January 1, 1998). In September 1998, an
NOV was issued for a surface emission in excess of 500 ppm on the
sideslopes, per APCD Rule 59 (Control of Waste Disposal Site Emissions,
1987). A letter was written by the owner two days after the NOV was
issued in response to the NOV. The letter indicated that the issue had
been addressed by working soil into erosion rills on the sideslopes and
filling cracks where gas was escaping. In December 1999, an NOV that cited two problems was issued. Odors were
being emitted from the condensate collection tank, in violation of San
Diego APCD Rule 59. The oxygen analyzer in the flare was not in good
working order (it was reading a negative value), in violation of the San
Diego APCD Rule 21 (Permit Conditions) requirement for keeping equipment
in good repair. The interviewee indicated that complying with the San Diego APCD
requirements for an oxygen analyzer in the flare has been problematic at
this site. The components of the LFG quickly degrade the analyzer, such
that extensive maintenance is required to keep it operational. It is the
interviewee’s understanding that the purpose of the oxygen analyzer is
to avoid fires within the waste mass by shutting down the system if the
amount of oxygen in the LFG exceeds 3.5 percent. However, the LFG fed
into the flare is comprised of gas extracted from numerous extraction
wells all over the landfill, so that the oxygen measured is not
representative of oxygen levels in discrete pockets of the waste mass. The owner is concerned about the upcoming selection of an appropriate
action to monitor for groundwater contamination commensurate with the
"non-beneficial use" designation that has been applied by the RWQCB in
the basin plan for groundwater in the vicinity of the site.
Information Source: San Diego Regional Water Quality Control Board
Telephone interview: March 18, 2004
E-mail response: April 20, 2004
The RWQCB regulates this site under a “general order” (97-11) rather
than a site-specific waste discharge requirement (WDR), since the site
is an inactive landfill closed prior to 1984. Hits of primarily VOCs
have been detected in site monitoring wells (30–100 feet below ground
surface). The owner has voluntarily developed a workplan for evaluation
monitoring to address these detections. Quarterly meetings are held with
the RWQCB’s larger landfill owners (including the owner of South Chollas—the
City of San Diego) to discuss site issues; the detection of COCs in
groundwater was discussed with the owner in 2001. Chollas Creek is near
the site and the possibility for metals from the site impacting the
creek is under consideration. The detection of COCs in groundwater has been low (less then 100
micrograms per liter) in most wells. LFG systems have been installed at
the site; these may help with VOC migration control. Detections began to
occur prior to 2001, with well data available back as far as 1987.
Regular monitoring didn’t start until 1997. No enforcement actions have been taken against the site in response to
the groundwater detections, primarily because the site has been
proactive in dealing with the issue. The interviewee indicated that once
an action is taken, the timelines for response (as defined in the
regulations) are strict. The release needs to be delineated within 90
days; the engineering feasibility study must be updated within 90 days;
and the WDRs must be amended within 90 days. If no action is taken and
the owner is proactive, as the owners of South Chollas Landfill have
been, the RWQCB is given more flexibility in imposing timelines. The site is currently unused but is open for development. Several
different parties have proposed uses but have withdrawn their proposals.
The site is also in a “non-beneficial use area” as defined by the
RWQCB’s Basin Plan for San Diego. The basin plan allows for protection
of groundwater based on risk-based concentration limits in
non-beneficial use areas. This risk-based assessment does not agree with
the State’s groundwater protection standards for landfills, which are
based on background.
Information Source: Enforcement Agency: City of San Diego, Development
Services Department
Telephone interview: March 17, 2004
E-mail response: April 13, 2004
Regulation of the landfill sites within the City of San Diego was
transferred from the county enforcement agency (EA) to the city EA in
November 1997. The city EA has limited records (copied from the county
EA files) of landfill performance prior to that time. The site is broken
into two general areas. The “big landfill” portion of the site is owned
by the City of San Diego and encompasses most of the site. A small area
of the site, adjacent to the Holy Spirit school is owned by the Catholic
Diocese of San Diego. The general issue at this site has been too few gas extraction wells.
Several additional wells have been installed in recent years to bring
the site into compliance. It takes time to fine-tune the system, and gas
migration has continued to occur. Full compliance with gas-related
concerns was reached in 2003, but then problems with the gas collection
system were encountered, and short-term violations have occurred.
However, the site has continued to move toward compliance and has
addressed individual violations in a timely manner, so enforcement
actions have been limited to inspection violations and official notices.
Most of the gas-related issues have been concentrated in the “big
landfill” portion of the site and very few in the smaller portion of the
site. The first gas-related concern identified by the city EA was in December
1998, involving a gas control violation. The site experienced gas
migration in at least 19 probes. This violation was not identified in
the landfill study’s Task 2 cross-media inventory. Various violations
for gas control (exceedance in gas probes) and explosive gas control
(surface migration) have been issued to the site based on the results of
EA inspections, and the owner has responded by installing additional gas
extraction wells to upgrade the system. Following is a chronological summary of the gas-migration-related
violations issued to the site during the period covered in the CIWMB
cross-media inventory (1998–2001). It should be recognized that the
interviewee identified more violations during this period than were
identified in the cross-media inventory: Jan. 1999: Violation for exceeding 5 percent in probes at east end of
landfill (near apartments). Feb. 1999: Violation for exceeding 5 percent in probes at east end of
landfill; additional wells installed and remediation plan submitted Feb.
4, 1999. May 1999: Violation with note indicating plan implemented and
improvement of levels on east side; elevated levels in probes on south
side. Sept. 1999: Violation for exceedance on east side, but levels much
improved; still exceeding levels on south side. Dec. 1999: Violation for exceedance on east and south sides; east side
just over limit (5.4 percent); south side decreased but still exceeding
limit; construction scheduled for new south side wells Feb. 2000. March 2000: Violation for exceedance in one south side probe; east side
probes in compliance. June 2000: No violations; in process of installing wells. Sept. 2000: Violation for exceedance in one south side probe (P-24). Dec. 2000: Violation for exceedance in one south side probe (P-22); P-24
in compliance. March 2001: Violation for exceedance in one south side probe (P-22),
though levels are lower. June 2001: No violations (all in compliance). Sept. 2001: Violation for exceedance in one south side probe (P-22 at
5.9%); 8/20 two new extraction wells were installed at top of slope
above P-22 and P-24. Dec. 2001: Violation for exceedance in one south side probe (P-26); P-22
in compliance. The EA identified more violations than what appears in the CIWMB
database for the years 1998 to 2001. Since January 2002, the “big
landfill” portion of the site has continued to receive violations for
gas control on a quarterly basis until December 2002, when it came into
compliance with the addition of new gas extraction wells. In September
2003, another gas-related violation was received for exceeding limits at
probes 12, 13, and 14. Blockages were identified by the owner at vaults
(extraction wells) 2a, 3a, and 4a that had brought them offline. A
strict monitoring schedule was assigned (twice a week) by the EA. Limits
were exceeded again in December 2003 at probes 12, 13, and 14, based on
her on-site inspection, but the blockages were cleared and gas levels
were decreasing. As of March 2004, there are 132 gas extraction wells
forming the gas collection system at South Chollas Landfill . The interviewee identified some difficulty in complying with LFG
requirements at older sites like South Chollas. The regulations require
compliance at the property boundary, but many of these sites, including
South Chollas, were configured to optimize airspace, and waste was
placed right up to the property boundary. Because the sites were opened
prior to the promulgation of LFG regulations, proximity to the boundary
was not a consideration. At this site, there are homes within 15 feet of
the property boundary on one side, so a relaxation of the regulations
for gas concentrations is not appropriate. Likewise, it would not be
appropriate to move the point of compliance beyond the property boundary
onto someone else’s property. At some other sites, buffer zones of
property have been purchased so that the point of compliance can be
pushed away from the waste limit. That has not been possible at this
site.
Information Source: San Diego County Air Pollution Control District
E-mail responses: March 23, 2004, April 22, 2004, and May 12, 2004
Two notices of violation (NOV) have been issued since Jan. 1, 1998. The
following summary of the NOVs was developed by the contractor for the
Landfill Facility Compliance Study from files provided by the APCD.
NOV #207508 (Sept. 15, 1998): Failure to maintain the gas collection
system in a manner such that the concentration of LFG does not exceed
500 ppm by volume measured as methane at any point immediately above the
surface of the landfill. Specifically, the concentration of LFG on the
south-facing slope of the eastern portion of the landfill was measured
at 600 ppm by volume approximately 2 inches above the surface. Response: A letter dated September 22, 1998 stated that the owner placed
dirt into erosion rills and reworked cover material to close up cracks.
NOV # 209459 (Dec. 14, 1999): Failure to maintain the oxygen analyzer in
good working condition. Specifically, the oxygen analyzer was broken and
was indicating readings of -1.3. Also, allowing condensate from the LFG
collection system to be released which resulted in the discharge of
odors. Specifically, a drain valve at the condensate tank had a liquid
leak, which resulted in the discharge. Additionally, the condensate tank
was equipped with a vent pipe open to the atmosphere, which also
resulted in the discharge of odors. Addendum to NOV # 209459 added December 22, 1999: Failing to maintain
the concentration of oxygen in LFG at the flare station of less than 3.5
percent by volume. Specifically, on August 31, 1999, the concentration
of oxygen in LFG at the flare was 4.0 percent by volume as indicated by
the oxygen analyzer. Also, failure to stop the flow of LFG to the flare
whenever the LFG oxygen content exceeded 3.5 percent by volume.
Specifically, on August 31, 1999, the flare continued to operate, and
LFG continued to flow when the oxygen content was 4.0 percent by volume
per operating records. Response: Per letter dated January 3, 2000, the owner emptied the
condensate liquid storage, and the drain valve leak was repaired. The
owner was in the process of ordering an activated charcoal filter medium
to place over the tank’s vent pipe to minimize odors. The oxygen
analyzer was repaired on Dec. 14, 1999, with a new sensor cell and
properly calibrated. The owner tested the sensor safety and shutdown
circuit after calibration. Subsequent inspections after Dec. 1999 found no violations of APCD
requirements. The last inspection conducted on Sept. 23, 2003, found the
South Chollas Landfill equipment operating in compliance with APCD
requirements.
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