ITEM 5 EXHIBITS A-H - Laserfiche WebLink

Protecting the infrastructure through innovative Corrosion Engineering Solutions 1100 Willow Pass Court, Concord, CA 94520 Tel No. 925.927.6630 Fax No. 925.927.6634 May 11, 2022 Cornerstone Earth Group, Inc. 1220 Oakland Boulevard, Suite 220 Walnut Creek, CA 94596 Attention: John R. Dye, P.E., G.E. Principal Engineer Subject: Site Corrosivity Evaluation 4400 Black Avenue Pleasanton, CA Project: 648-26-1 Dear John, In accordance with your request, we have reviewed the laboratory soils data for the above referenced project site. Our evaluation of these results and our corresponding recommendations for corrosion control for the above referenced project foundations and buried site utilities are presented herein for your consideration. Soil Testing & Analysis Soil Chemical Analysis Two (2) soil samples from the project site were chemically analyzed for corrosivity by Cornerstone Earth Group. Each sample was analyzed for chloride and sulfate concentration, pH and resistivity at 100% saturation. The test results are presented in Cornerstone Earth Group Geotechnical Report dated 5/9/2022. The results of the chemical analysis were as follows: Soil Laboratory Analysis Chemical Analysis Range of Results Corrosion Classification* Chlorides 3 14 mg/kg Non-corrosive* Sulfates 11 21 mg/kg Non-corrosive** pH 7.0 7.1 Non-corrosive* Resistivity at 100% Saturation 4,347 5,639 ohm-cm Moderately Corrosive* * With respect to bare steel or ductile iron. **With respect to mortar coated steel In accordance with your request, we have reviewed the laboratory soils data for the above In accordance with your request, we have reviewed the laboratory soils data for the above referenced project site. Our evaluation of these results and our corresponding referenced project site. Our evaluation of these results and our corresponding recommendations for corrosion control for the above referencedrecommendations for corrosion control for the above referenced buried site utilities are presented herein for your consideration. buried site utilities are presented herein for your consideration. Soil Testing & Analysis Soil Chemical Analysis Two (2) soil samples from the project site were chemically analyzed for corrosivity by Two (2) soil samples from the project site were chemically analyzed for corrosivity by Cornerstone Earth GroupCornerstone Earth Group. Each sample was analyzed for chloride and sulfate concentration, . Each sample was analyzed for chloride and sulfate concentration, pH and resistivity at 100% saturationpH and resistivity at 100% saturation Group Geotechnical Report dated Group Geotechnical Report dated