SU0012197 - Laserfiche WebLink

Home Browse Search

LOGE 1928: American Crane Rental Page 4 May 29, 2019 gallons for each employee is typical for an office or industrial worker and 5 gallons is typical for a public restroom user. These rates were used for the employees of the facility and the daily departing truckers. The use rate for employees and customers (Q) is calculated as follows: Table 2. Average Daily Flow Calculation, Current Project Use Units Rate Subtotal Reduction* Average Daily Flow Office Workers 10 13 gal/person 130 gpd 5/7 92.8 gpd Mechanics 8 13 gal/person 104 gpd 5/7 74.3 gpd Yard Workers 2 13 gal/person 26 gpd 5/7 18.6 gpd Crane 10 5 gal/person 50 gpd 5/7 35.7 gallons Operators, per day on-site 15-30 min Crane 10 0 gal/person 0 gpd 5/7 0 gpd Operators, dispatched directly to job sites Total 221.4 gpd *Reduction factors convert calculated flow into average daily flow over a year. The factor 5/7 refers to days per week. Total nitrogen levels from commercial wastewater uses are known to be higher in concentration compared to residential levels, which include significant dilution from washing water. The typical residential wastewater range is reported to be 20 to 85 mg/L-N (Crites and Tchobanoglous, 1998). Since reference material for commercial restroom uses is limited, we assume total nitrogen is similar to higher residential values; therefore, 85 mg/L-N is selected as Nw. Based on San Joaquin County Environmental Health Department policy (personal communication, March 18, 2019), the recharge input (R) for the Hantzsche and Finnemore equation should be derived from average monthly precipitation of rainfall and evapotranspiration rates for the area; the data should be obtained from the California Irrigation Management Information System (CIMIS), preferably from stations located within San Joaquin County. Recharge is calculated by first determining whether the average monthly precipitation exceeds average monthly potential evapotranspiration. If so, then the difference is the percolating recharge water into the aquifer. Runoff and stream infiltration drainage are not factored into the calculation. This approach likely under-estimates recharge to the aquifer and, consequently, over-estimates nitrate loading.