SU0002230 - Laserfiche WebLink

Home Browse Search

Wastewater Treatment System FALL CREEK Engineering Report ENGINEERING,INC. Rainfall (Rd. Rainfall is the depth of the direct monthly rainfall on the wetland, field, or stormwater detention area. It is calculated by multiplying the monthly rainfall in inches (rt) by the area of the element (A) as given by the following equation. The wetland, field, and _. stormwater detention area areas were assumed to be approximately, 9,400, 13,000, and 3000 square feet respectively. Rt( 748 1 gal 1 * * inches month) — 12 . rt(month) A(Sf) %' Infiltration (Id. Monthly infiltration of water into the soil beneath the grass field and the stormwater detention area is a means of water outflow from the system (the wetland is assumed ` to be lined with no infiltration). Water applied in excess of the available water capacity of the soil will percolate beyond the root zone in the grass field and the grass-bottomed stormwater detention area and enter the underlying groundwater. Soil at the site has been described by the ,%W Winery as a sandy loam. This soil type is generally assumed to have moderately rapid permeability and has clear water infiltration rates of 2.0 to 8.0 inches per hour (WEF, 1990). The design infiltration rate is assumed to be much less than the clear water infiltration rate because of the gradual plugging of the soils. The design infiltration rate was estimated to be just 2% of the clear water infiltration rate (conservatively considered 2.0 in/hr). Average soil infiltration rate (i) was estimated at 1.0 inches per day (30 in/month). It( gal _ 1 #7.481*rmches * days month) 12 ( day ) A(sf),Ic d(month) s Evapotranspiration and Evaporation (Ed. Evapotranspiration rate coefficients for the irrigated grass field was found in the University of California Reference Evapotranspiration Bulletin. It _ was assumed that the evapotranspiration of the wetland would be the same as the grass field. Evaporation from water surfaces on the stormwater detention area was found in the University of California Evaporation from Water Surfaces in California reference bulletin. Monthly evapotranspiration rates for both of these are presented Table 3.2. Table 3.2. Monthly Evapotranspiration/Evaporation Rates (in/month) JAN FEB MAR APR I MAY I JUN I JUL I AUG I SEP I OCT 1 NOV 1 --- Water Surface 1 1.10 1.93 3.86 1 6.02 8.82 1 8.90 1 11.34 1 9.72 1 7.28 1 4.41 1 1.93 1 1.06 Grass 0.91 1.43 2.78 1 4.24 5.88 1 6.95 1 7.05 1 6.17 1 4.62 1 2.91 1 1.49 1 0.76 Evapotranspiration rates were multiplied by disposal surface area to estimate the monthly volume of water evaporated as follows. EE ( gal ) _ *7.481*e,(`aQ es)*A(sf)*d(manth) , month 12 y Process wastewater (Pd. The current monthly process water was estimated as described in Section 2.2. Process water is given in gallons per month. Stormwater (Sd. Stormwater was estimated for average and high rainfall years as described in �- Section 2.2. Stormwater is given in gallons per month. JESSIE's GROVE WINERY MAY 2002 _ 11