Laserfiche WebLink
For the fill samples, Consultant will conduct to complete a DI -WET extraction prior to conducting analyses <br />for TPHd, TPHmo, 17 heavy metals, PCBs, and pesticides to evaluate leachability in an unstabilized <br />condition. The laboratory will perform these analyses on a standard seven-day turnaround. <br />Consultant will compile the analytical and compare the results with background concentrations, <br />Environmental Screening Levels (ESLs), and Water Quality Objectives established by the RWQCB. The <br />RWQCB believes that soil concentrations below the ESLs do not pose a significant threat to human health <br />and the environment. On the basis of the data, Consultant and City will determine the need and scope for a <br />bench scale treatability study to evaluate stabilization of sludge and fill material to protect water quality at <br />the project site. <br />Technical guidance prepared by the United States Environmental Protection Agency (USEPA), as well as <br />other regulatory agencies, indicates that chemical stabilization using Portland cement or lime is a proven <br />and suitable technology for the treatment of lead and other chemicals in soils. Stabilization refers to those <br />techniques which reduce the hazard potential of a waste by converting the contaminants into less soluble, <br />mobile, or toxic forms. Typically the ratio of binder material to dry weight soil ranges from 5-30% for <br />Portland cement and 10-30% for lime. The feasibility of stabilizing the impacted sludge and fill material will <br />be assessed using a bench -scale study. Consultant completed a similar study for lead -impacted fill and <br />sludge at WPCP equalization pond. Results of that study confirmed that mixing soil with 10% Portland by <br />weight would successfully stabilize soluble lead concentrations. Accordingly, Consultant will limit the bench - <br />scale testing to Portland as an additive. <br />If needed and assuming that soluble lead is the chemical of concern, Consultant will conduct the following <br />bench -scale test to confirm the chemical stabilization of the sludge and fill is appropriate: <br />• Obtain approximately 20 gallons of sludge and 20 gallons of fill for the treatability study. Samples <br />will be collected by hand and will be stored in 5 -gallon buckets pending homogenization and <br />testing. <br />• Homogenize the sludge and the fill samples to create more uniform mix for each matrix. <br />• Perform Initial Sample Characterization testing on the homogenized soil. Tests will include some or <br />all of the following: <br />o Moisture Content <br />o Grain size distribution <br />o Atterberg limits <br />o pH <br />o Total Organic Carbon <br />o Total Lead using EPA Method 6010 <br />o Soluble Lead using WET and TCLP methods <br />• Perform bench study to determine the feasibility of stabilizing the sludge and fill. Uniform weights of <br />homogenized samples will be mixed with ratios of 5%, 7.5%, 10%, and 15% of Portland cement to <br />total soil weight. Consultant will add tap water as needed to facilitate mixing. The amount of water <br />added will be recorded. <br />• Stabilized soil samples will be cured for at least 7 days prior to any chemical testing. <br />Consulting Services Agreement between [EFFECTIVE DATE] <br />City of San Leandro and —Exhibit A Page 3 of 5 <br />