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Leighton will collect soil gas samples by syringe. Soil gas samples will either be analyzed <br />by an on-site mobile laboratory or an off-site State of California -certified laboratory. The <br />analytical results will have detection limits suitable to conduct a screening level health risk <br />assessment (HRA) for indoor air intrusion using the current DTSC-modified version of the <br />Johnson and Ettinger (I&F) Model for Subsurface Vapor Intrusion into Buildings. The results <br />of an HRA can be used to determine if remediation is necessary for the intended site use if <br />hazardous substances are identified in the soil vapor samples. <br />Leighton personnel will direct the soil gas sampling subcontractor to assess the <br />presence/absence of volatile organic compounds in soil vapor. Leighton will use this <br />method of investigation to assess the health risks of contaminants and/or identify point <br />sources of impact. <br />Whenever possible, Leighton will subcontract a mobile laboratory for on-site services. The <br />use of a mobile laboratory provides real-time data and enables us to make in -field decisions <br />regarding drilling locations and often results in significant cost and time savings. For off-site <br />testing, Leighton will contract with State of California Department of Health Services - <br />certified laboratories. All analyses will be performed in accordance with Contract <br />Laboratory Program (CLP) protocol. Leighton will be responsible for sample transport from <br />the work site to the laboratory, new sample containers, labels, appropriate preservation, and <br />Chain of Custody records. <br />N Asbestos and Lead -Based Paint <br />Leighton will subcontract this service to Sigma Engineering. <br />• Review of submittals and confirm worker training, and medical and respiratory fit test <br />a certifications from the abatement contractor. <br />Observation of work procedures and preparation of daily progress reports summarizing <br />work methods. <br />• Daily air monitoring during abatement procedures (asbestos). <br />Leighton Consulting, Inc. Page <br />Statement of Qualifications for Environmental Consulting Services <br />City of Santa Ana, Public Works Agency <br />approved by the Orange County Fire Authority as an engineering contractor for performing <br />Combustible Soil Gas Hazardous Mitigation. <br />Leighton will install the soil vapor probes utilizing a direct -push system or a hollow -stem <br />auger rotary drill rig. A small diameter, inert nylaflow tube with an attached sampling filter <br />will be inserted into each boring upon reaching the desired depth. The boring will be back- <br />filled with approximately one foot of sand filter -pack after installation. Hydrated granular <br />bentonite will be placed from the top of the sand filter pack to approximately 6 inches <br />below grade. All probes will be sealed with granular bentonite for a minimum of 20 <br />minutes prior to sample collection. Cold -patch asphalt will be placed above the hydrated <br />granular bentonite and completed flush with grade following the soil gas sampling <br />activities, assuming that the subsurface conditions will allow for the probe installations as <br />described. <br />Leighton will collect soil gas samples by syringe. Soil gas samples will either be analyzed <br />by an on-site mobile laboratory or an off-site State of California -certified laboratory. The <br />analytical results will have detection limits suitable to conduct a screening level health risk <br />assessment (HRA) for indoor air intrusion using the current DTSC-modified version of the <br />Johnson and Ettinger (I&F) Model for Subsurface Vapor Intrusion into Buildings. The results <br />of an HRA can be used to determine if remediation is necessary for the intended site use if <br />hazardous substances are identified in the soil vapor samples. <br />Leighton personnel will direct the soil gas sampling subcontractor to assess the <br />presence/absence of volatile organic compounds in soil vapor. Leighton will use this <br />method of investigation to assess the health risks of contaminants and/or identify point <br />sources of impact. <br />Whenever possible, Leighton will subcontract a mobile laboratory for on-site services. The <br />use of a mobile laboratory provides real-time data and enables us to make in -field decisions <br />regarding drilling locations and often results in significant cost and time savings. For off-site <br />testing, Leighton will contract with State of California Department of Health Services - <br />certified laboratories. All analyses will be performed in accordance with Contract <br />Laboratory Program (CLP) protocol. Leighton will be responsible for sample transport from <br />the work site to the laboratory, new sample containers, labels, appropriate preservation, and <br />Chain of Custody records. <br />N Asbestos and Lead -Based Paint <br />Leighton will subcontract this service to Sigma Engineering. <br />• Review of submittals and confirm worker training, and medical and respiratory fit test <br />a certifications from the abatement contractor. <br />Observation of work procedures and preparation of daily progress reports summarizing <br />work methods. <br />• Daily air monitoring during abatement procedures (asbestos). <br />Leighton Consulting, Inc. Page <br />