Item 16 - Agreements for A -Tech Consulting, Inc., Dudek, and Leighton Consulting, Inc. for On -Call Various Environmental Services

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Leighton recommends a kick-off meeting prior to initiating any Site Investigations to establish project priorities and identify restrictions. Prior to the meeting, we will review any available background information so we are prepared to discuss investigative methodologies applicable to the particular project. Based on the results of this meeting, we will develop a Work Plan for the field investigation. All investigations will be completed under the direction of a Professional Geologist (PG), Professional Engineer (PE), Certified Hydrogeologist (CHG), or Certified Engineering Geologist (CEG), in accordance with the requirements and applicable governing oversight agency such as LARWQCB, DTSC or local CUPAs. The Work Plan will be based upon our review of site conditions and meetings/discussions with the City. Each Work Plan will include a specific technical scope of work developed to best suit the needs of the project. A draft of the Work Plan will be submitted to the City's Project Manager for review. Once approved by the City, the final Work Plan will be submitted to the appropriate agencies for review and approval, if required. All Work Plans will be reviewed and signed by an appropriate licensed professional (PG or PE) before field implementation. Investigative methods described in the Work Plan may include one or more of the following: Waste Profiling: Containers of unknown contents are often discovered on industrial facilities associated with properties. Leighton's team is well trained and equipped to perform inspection, profile sampling, and characterization of chemical storage containers, such as tanks, drums, and other vessels. We realize that these assessments are often required on an expedited basis and our staff is prepared to respond immediately to your needs. When appropriate, Leighton will work with approved subcontractors to complete geophysical surveys. Subsurface geophysical techniques can also be applied to screen locations prior to other invasive work, such as drilling and trenching. Direct Push Soil Sampling/Soil Gas Surveys: Leighton has completed hundreds of soil, groundwater, and soil gas investigations using direct push field equipment to evaluate the presence, concentrations, and extent of petroleum hydrocarbons, heavy metals, VOCs, methane and other contaminants that may be encountered on properties. This technology has been increasingly important in recent years due to concerns of potential vapor intrusion into above -ground structures and is often a critical component of evaluating potential health risks. Our personnel are well versed in the implementation of this technology as well as the evaluation of the data generated and will oversee direct push drilling subcontractors in the completion of soil gas investigations, when required. Soil gas investigations will be completed in accordance with RWQCB/DTSC guidelines and requirements. When necessary, Leighton will work closely with Dr. Heriberto Robles of Enviro-Tox Services to assess the potential for vapor intrusion into buildings/ structures and the associated health risks of identified contaminants. Trenching is a cost-effective alternative often used for shallow soil characterization and to assess presence of or levels of contamination. Trenching activities will be supervised by Leighton personnel, under our current Cal/OSHA trenching permit. If potentially contaminated soils are encountered during excavation, Leighton will first notify the City, and then once approved accordingly notify the South Coast Air Quality Management District (AQMD) under our various locations Rule 1166 permit for soil excavation, or other applicable agencies, depending on the project location. Drilling: We understand that drilling soil borings or installing groundwater monitoring wells may be required under this contract. Having significant experience in California spanning more than 57 years, we understand the regional subsurface geologic and hydrogeologic conditions and can select the most appropriate drilling methods for each project based upon this knowledge. On most properties, we would utilize a direct push rig to collect soil and initial grab groundwater samples. This field methodology is less intrusive and considerably more cost-effective than drilling with hollow -stem auger drill rigs, and generates relatively little investigation derived waste (IDW) for disposal. Where permanent groundwater monitoring wells are required, Leighton will primarily use hollow - stem auger drilling equipment to advance soil borings for well installation. We have overseen the installation of thousands of groundwater monitoring wells from single completions in shallow water bearing units to multi -nested completions in confined and multilayered aquifers. We have designed and installed monitoring wells intended for the recovery of various contaminants including petroleum hydrocarbons, VOCs, various light non - aqueous phase liquids (LNAPLs — floating product), dense non -aqueous phase liquids (DNAPLs), and other dissolved compounds. Prior to any monitoring well installation, Leighton will obtain necessary permits from the appropriate regulatory agencies and register wells with the Department of Water Resources (DWR) as required. Drilling will be performed under the oversight of a PE or PG registered in the State of California. llLei ghton 10