SR0084773_SSNL - Laserfiche WebLink

Home Browse Search

Values and Assumptions: 1= 159,750 gals/yr = total WW/yr = 21,357 cu ft = 0.146 in/yr 40.36 Ac x 43,560 sq ft/Ac x (1 ft/12 in) Nw = 45 mg N/L d = 30% R = 8.82 in/yr. Nb = Assumed to be 0.1 ppm NO3-N 0.146 in/yr (45 mg N/L) (1- 0.30) + (8.82 in/yr • x 0.1 mg/L) Nr = • (0.146 in/yr + 8.82 in/yr) Nr = 0.61 ppm as nitrate-nitrogen (NO3-N) or 2.7 ppm as nitrate (NO3) IV. OWTS DESIGN SPECIFICATIONS AND OPERATIONAL PURVIEW To adequately design the OWTS for this project, effluent flow volumes must be estimated as accurately as possible. As noted on the Site Plans, fixtures to be installed in the new office building include two restrooms, each with a toilet and lavatory, two sinks (kitchen and mop) and a dishwasher. Historically, a Water Use Computation Factor Table referencing gallons per person per day for each type of establishment was used to determined wastewater flow volumes. The Building Occupancy Load Table for the office building indicates a total of 48 people could occupy the building. However, an indeterminable fraction of this total will occupy the building since occupancy of the Foyer, Conference Room and Break Room could constitute 41 people of the 48 potential total occupants. Since water flow volumes from contemporary plumbing fixtures is much lower than years prior, daily wastewater volumes for this project will be based on an assumed maximum fixture usage, as calculated below. Wastewater flow volumes from the office building Restrooms will be based on four flushes of each toilet per hour, daily use of the dishwasher, and 10 gals sink use: 1.5 gals flush + 0.5 gals hand washing = 2 gals/use x 4 flushes/hr x 10 hr/workday = 80 gpd x 2 Restrooms = 160 gpd 160 gpd + 5 gpd (dishwasher) + 10 gpd (sinks) = 175 gpd = Average Daily Flow (ADF) from Office Building. To maintain a comparatively small effluent disposal area footprint, a filter bed structure is proposed, as calculated: 1,200 Base Tank Capacity (BTC) + 175 ADF =1,375 gals. 1,375 gals x 0.225 (Sandy Loam Soil Factor) = 310 Lineal Ft of Leachline (LFLL) 310 LFLL x 3 (Filter Bed Soil Factor) = 928 sf Filter Bed (30 ft x 30 ft square). A drill rig was used to determine the underlying soil profile and drill soil percolation test borings in the approximate location of the proposed filter bed. The 24 ft exploratory boring was converted to a deep perc test and two shallow percolation tests were drilled for a total of three perc tests conducted. The observed soil profile consisted of the following strata illustrated in Table 1 with the perc test results and application rates for the three borings in Table 2: Page -3- J Chesney Consulting