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Flagler, Colorado Site Investigations USTs Remedial Design/Remedial Action Construction Observation Remedial O&M Regulatory Compliance Air Monitoring/ Permitting Data Management Client: Flagler Farmer's Co-Operative Completion: Ongoing Cost: $210,000 |
The Flagler Farmer's Co-Operative (Co-Op) operated a service station,
which they had closed. The underground storage tank (UST) was
removed in 1995, and contamination detected. Subsequent subsurface
investigations indicated that ground water had been impacted, and that
the plume has migrated off-site. Groundwater at the site is approximately
80 feet below ground surface.
Pinyon conducted the subsurface investigation and completed a Corrective
Action Plan, as required by Colorado. The plan evaluated several
remedial options, and identified the positive and negative considerations for
each. The selected remedial option at the site involved installation of a
combined soil vapor extraction (SVE) and air sparging (AS) system.
This system is highly efficient in removing petroleum hydrocarbons from
soil and ground water.
Pinyon assisted the Co-Op in evaluating their eligibility for the State
reimbursement program, and in their application.
A pilot study was conducted in the winter of 1995 to evaluate the feasibility of using SVE and AS at the site and to determine the number of wells necessary to remediate the site. Pinyon prepared the design and provided construction management for the system installation.
Pinyon obtained an air pollution emission notice (APEN) for the discharge of extracted soil vapors. Continuous operation of the system began in November of 1997. Due to the systems's ability to effectively extract vapors from the subsurface, the system reached the APEN limit in both 1998 and 1999, and had to be shut down until the beginning of the next operating year.
Pinyon routinely conducts site visits to monitor system operating parameters, perform system
maintenance activities, conduct ground-water monitoring, and obtain water level and soil vacuum
measurements. This data is utilized to evaluate the effectiveness of the remediation system.
In addition, Pinyon submits quarterly ground-water monitoring reports as required by the state. |
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Denver, Colorado Site Investigations USTs Remedial Design/Remedial Action Construction Observation Remedial O&M Regulatory Compliance Waste Water
Data Management Project Management Client: City & County of Denver and The Denver Zoological Foundation Completion: Ongoing Cost: $175,000 |
A vendor at the Denver Zoological Gardens operated a small train ride at
the Children's Zoo for numerous years. Fuel for the train was stored in an
underground storage tank (UST). Used oil generated during the
operations was stored in a separate UST. Both tanks were removed in 1994
during demolition activities. The site was then developed as a state-of-the-art primate exhibit. During removal of both tanks contamination was
detected. Subsequent subsurface investigations indicated that ground
water had been impacted.
Ground-water contamination was detected in the alluvial sands and clay.
The plume has migrated from the immediate area.
In order to not delay construction of the primate exhibit, Pinyon utilized a
"geo-probe" sampling system with an on-site laboratory to delineate the
extent of soil contamination. After two days of field work, the contamination had been defined within the areas of planned construction. In addition,
ground-water monitoring wells were installed and sampled to evaluate
ground-water quality. Ground water had been impacted by the release and
appeared to be migrating off-site towards the northwest.
Pinyon prepared a Corrective Action Plan (CAP) recommending that additional soil be removed from the former tank excavations and that ground-water monitoring be conducted. During the course of monitoring, Pinyon discovered that the ground-water flow direction had been reversed. This was a result of the construction of a deep moat and associated dewatering system. In addition, free product was observed in one of the wells.
Pinyon responded immediately to mitigate potential hazards and to implement a remediation system.
The remediation system involved the collection and treatment of free product, and the installation of an
air sparging/soil vapor extraction system. Pinyon obtained the appropriate discharge permits.
This system is currently operating.
Pinyon has revised the CAP to reflect the new conditions. Quarterly ground-water monitoring is being
conducted. Discharge monitoring was conducted; however, due to the effectiveness of the
remediation system, monitoring is no longer required by the state.
The SVE and sparging portions of the remediation system continue to reduce contaminant concentrations in the local ground water. |