Monitoring and Inspections, NAS North Island, CA
Monitoring and Inspections, NAS North Island, CA
Trevet has conducted long-term monitoring, inspection, and maintenance activities at Naval Air Station (NAS) North Island operable units (OUs) 2, 4, 5, 10, and 11 since 2008.
The OU 2 Landfill and Storage Yard, the Old Spanish Bight Landfill, undergoes quarterly post-closure monitoring and maintenance and land use control (LUC) inspections. Identified deficiencies have assisted the Navy in complying with the regulatory agency requirements. Vegetation removal in the sloped landfill cap area and storm drain system ensure that site conditions are maintained.
OU 4, the Former Public Works Salvage Yard, consists of an approximately four acre area within golf course driving range inspected quarterly. Most recently, minor rills were observed forming on the surface of the cap on the site, providing the Navy with the information needed for assessing potential repairs.
OU 5 is a golf course that includes subsites identified as Units 1 and 2. Post-closure monitoring and maintenance activities at Unit 1, a former cut-and-cover sanitary landfill, consist of quarterly inspections and have included a geotechnical and engineering evaluation of subsidence and a depression in the area. Natural attenuation monitoring at Unit 2, a former liquid water disposal area, is performed quarterly in conformance with record of decision requirements. LUC inspections are performed quarterly at both subsites.
OU 10, the Shoreline Slag Area and Waste Consolidation Area, includes metal slag and low-level radioactive objects (LLRO) such as radium-226 containing dials. Annual groundwater and periodic stormwater sampling events are conducted to evaluate cap effectiveness in preventing impacts to groundwater and possible dissolved copper and zinc releases to the San Diego Bay. Trevet installed metal filtering absorbent socks as an engineering control to mitigate the potential releases and surface water impacts to the bay. Biological and radiological surveys were conducted to assess the effectiveness of ongoing vegetation maintenance in providing habitat for native species and of the cap in containing LLROs.
OU 11 is a RCRA-permitted industrial wastewater treatment plant where volatile organic compound, per- and polyfluoroalkyl substances, and hexavalent chromium contamination were released to soil and groundwater from 20 former surface impoundments. Fifty groundwater monitoring wells and three soil gas monitoring wells are sampled quarterly, and program optimization recommendations are made annually. A modified RCRA cap is also inspected for integrity quarterly.
“By communicating early with the Navy and agencies, the Navy was able to submit proposed optimizations to the analytical suites at each NASNI OU11 well location in advance with recommendations to be implemented in the 2022 calendar year. This also allowed the Navy to better plan their budget for the 2022 calendar year. Based on the successfully completed work above and excellent services provided, the contractor performance as it pertains to quality is exceptional.” – NAVFAC Southwest
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