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• For the fill samples, Consultant will conduct to complete a DI-WET extraction prior to conducting analyses for TPHd, TPHmo, 17 heavy metals, PCBs, and pesticides to evaluate leachability in an unstabilized condition. The laboratory will perform these analyses on a standard seven-day turnaround. Consultant will compile the analytical and compare the results with background concentrations, Environmental Screening Levels (ESLs), and Water Quality Objectives established by.the RWQCB. The RWQCB believes that soil concentrations below the ESLs do not pose a significant threat to human health and the environment. e• :- •- - . -:• •• • • •- -•••'•- •- •- -- •• --- the project citn zTiv-�r°�cor�rrc A bench scale stabilization study is included in this task and will be done if required by the City. Technical guidance prepared by the United States Environmental Protection Agency (USEPA), as well as other regulatory agencies, indicates that chemical stabilization using Portland cement or lime is a proven and suitable technology for the treatment of lead and other chemicals in soils. Stabilization refers to those techniques which reduce the hazard potential of a waste by converting the contaminants into less soluble, mobile, or toxic forms. Typically the ratio of binder material to dry weight soil ranges from 5-30% for Portland cement and 10-30%for lime. The feasibility of stabilizing the impacted sludge and fill material will be assessed using a bench-scale study. Consultant completed a similar study for lead-impacted fill and sludge at WPCP equalization pond. Results of that study confirmed that mixing soil with 10% Portland by weight would successfully stabilize soluble lead concentrations.Accordingly, Consultant will tirnituse Portland cement as an additive for the bench-scale testing . If needed and assuming that soluble lead is the chemical of concern, Consultant will conduct the following bench-scale test to confirm the chemical stabilization of the sludge and fill is appropriate: • Obtain approximately 20 gallons of sludge and 20 gallons of fill for the treatability study. Samples will be collected by hand and will be stored in 5-gallon buckets pending homogenization and testing. • Homogenize the sludge and the fill samples to create more uniform mix for each matrix. • Perform Initial Sample Characterization testing on the homogenized soil. Tests will include some or all of the following: o Moisture Content o Grain size distribution o Atterberg limits o pH • o Total Organic Carbon o Total Lead using EPA Method 6010 o Soluble Lead using WET and TCLP methods • Perform bench study to determine the feasibility of stabilizing the sludge and fill. Uniform weights of homogenized samples will be mixed with ratios of 5%, 7.5%, 10%, and 15%of Portland cement to total soil weight. Consultant will add tap water as needed to facilitate mixing. The amount of water added will be recorded. Consulting Services Agreement between City of San Leandro and Carollo Engineers, Inc.—Exhibit A Page 3 of 5