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LOGE 1928: American Crane Rental Page 3 June 19, 2019 For the recharge rate of rainfall (R), Provost & Pritchard use a value of 11.5 inches per year; no source is cited. It is our opinion that this value most likely derives from Figure 3 of the Soil Survey of San Joaquin County, California (1992). As of March 2019, the Environmental Health Department has requested that the recharge rate of rainfall be calculated in a specific way, as discussed later in this letter. The assumptions and result of the nitrate loading calculation prepared by Provost & Pritchard are as follows: Table 1. Inputs and Results for Nitrate Loading Calculation, Provost & Pritchard, 2012 Variable Value Units Description Q 126,225 gal/year Effluent flow rate (345.8) (gpd) (33 people * 15 gal/person*255 work days/year) Nw 82 mg/L-N Effluent stream concentration (discussed in report) A 8.42 acres Site area Nb 0.1 mg/L-N Concentration of rain (source not cited) d 0.15 constant Denitrification factor ("fine-grained silty sand soil") R 11.5 inches per year Recharge rate of rainfall (source not cited) 1 0.55 inches per year Uniform waste water loading (calculated) Nr 3.3 mg/L-N Long-term average concentration of percolating effluent Assessment of Current Conditions Using EHD-Recommended Methods The current project includes all of APN 208-180-23, 11.80 acres in size (A). Employee levels are discussed in Exhibit A of the Use Permit application. The facility will only be operated Monday through Friday. Anticipated employees are as follows: • 10 office workers, 8 a.m. to 5 p.m.; • 8 mechanics, 8 a.m. to 5 p.m.; • 2 yard workers, 8 a.m. to 5 p.m.; • 10 crane operators, arriving at the office each morning for 15 to 30 minutes prior to dispatch to job site for remainder of day; • 10 crane operators, dispatched directly to job site without visiting office. No customers are anticipated.