SU0006343 SSNL - Laserfiche WebLink

Home Browse Search

Q =472 gpd(From Max.flow volume calcs. from Phase H,Page 12)-7.48 gals/ft''—63 ft/day A =2,600 ft(From mound system potential as sized on Site Plans) C=Length to width ratio z 1.0,therefore,C=3.4179 L=55ft K=Using average vertical permeability as most conservative= min/in: 1440 min/day-32 min/in=3.8 ft/day h=2.75(See above) n=Length to width ratio =1,therefore,n= 1.7193 Sy=8% t =3,650 days(10 yrs) Z. =0.0828 x 31.67 x 0,1330 x 2.36=0.83 ft It appears that the maximum mound height that may occur under mound system is 0.83 feet. This would leave a distance of approximately 5.17 feet between the soil/effluent interface at a mound system disposal structure, and the top of the theoretical groundwater mound above the elevation of the water table: 4.5 ft minus 0.83 ft =3.67 ft+ 1.5 ft (Ht.of soil-effluent interface above ground surface)= 5.17 ft. For wastewater treatment to occur, the distance effluent should travel under unsaturated conditions through the soil environment is generally regarded to be 5 feet. Additionally, the Cali ornia State Water Resources Control Board- Guidelines for the Design, Installation and Operations of Mound Sewage Disposal Systems document states in Section 31.0 that in cases where peak wastewater flows for a commercial system exceed 1,500 gallons per day, an evaluation of hydraulic mounding below the disposal area shall be performed. Although the daily flows will be substantially lower than this volume, mound potential analysis as completed above, remains viable. In the Finnemore and Hantzsche paper, they discuss three options to consider as potential methods of reducing the mounding phenomenon. The first is increasing the size of the disposal field. The second method is elongating the shape of the area covered by the disposal field. Thirdly, operating the field intermittently should decrease the mounding effect. If it is determined at some point in the future that moun ' g effects are preventing proper effluent treatment and disposal of effluent from the Gurudwara Sahib, the area designated as the 100% replacement areas may have to be activated. The reserve area is located directly north, and to the west of the primary disposal area. C E. SURFACE WATER INFORMATION Storm water management is proposed to be an on-site retention basin that will be constructed with minimal excavation and built-up embankments. This is to maintain a five-foot separation distance between the floor of the basin and the depth to groundwater. There should be no impact to percolating effluent from the retention basin. The retention basin can be considered upgradient to the proposed wastewater disposal area with respect to groundwater directional flow. Since the groundwater directional flow is assumed to be north-northeast,percolating rainwater from this basin into the top aquifer mixing layer may create a dilution effect to the percolating wastewater effluent. 9 Chesney Consulting