SR0082149 - Laserfiche WebLink

Home Browse Search

n , ENGINEERING 1242 DUPONT COURT MANTECA , CALIFORNIA 95336 TEL : 209 . 239 . 6229 FAX : 209 . 239 . 8839 Introduction This report conducted for the "New Haven Modernization" proposed septic systems . The report was conducted to formerly explain the methodology and calculations used in sizing the school ' s septic system . The New Haven Elementary School Septic dispersal fields will consist of an existing leach field and two proposed leach fields, noted as "Leach Field A" and "Leach Field B ", (see site plan) . Proposed Leach Field "A" will disperse the entire school ' s wastewater flowrates, except the flowrates going to Proposed Leach Field `B" and the existing leach field. Proposed Leach Field `B " will disperse the New Building (H) flowrates only . The existing leach field and flowrates are not being modified by the proposed improvements . The existing leach field will continue to service the existing building (D) . Building (G) is a modernization building that' s purpose is to replace an existing building being removed by these improvements and does not contribute any additional flowrate to the existing system . The flowrates from Building G are to continue to be routed to an existing pump station that discharges into proposed leach field A . Please see the Reference Equations section at the end of this report for any equations referenced. Methodology The proposed septic calculations were conducted to accurately disperse the entire schools ' flowrates to their corresponding septic systems and then accurately size the systems based on their requirements . The first step in creating an accurate assessment is to calculate the unit flowrates to be used for design, please refer to the "Unit Flowrate Design Calculations" . Next the max daily flowrates (MDF) and average daily flowrates (ADF) must be calculated for each system; the max flowrate will be used for designing the leach field, and the average daily flowrate will be used to design the septic tanks . This is because max flowrate has no effect on the size of the septic tank, which is based on the average flowrate only . After calculating the design flowrates, the septic tank and leach field are calculated . Design Flowrates System A : System A consists of multiple existing upstream septic tanks and a proposed leach field. The proposed leach field is designed to service the entire schools wastewater flows, except flowrates to the existing septic system and the proposed system B ; therefore, the ADF for System A is simply the entire schools flowrates minus the flowrates from Proposed Building H and existing Building D . 1 . Unit Flowrate Per Person = 10 gal/person/day 2 . ADF = 7,460 gal/day a. System ADF ' s i . Total School ADF 1 . Total = (40 Staff + 894 Students) * 10 gal/person/day = 9,340 gal/day ii . Existing Building (D) ADF (To existing leach field) 1 . Total = ( 1 Staff/Room + 20 Students/Room) * 6 Rooms * 10 gal/person/day = - 1 ,260 gal/day iii . Proposed Building (H) ADF (To system B ) 1 . Total = (2 Staff + 60 Students) * 10 gal/person/day = - 620 gal/day b . System A ADF = 9,340 — 1260 — 620 = 7,460 gal/day 3 . Since this system does not have any varying flowrates the MDF is equal to the ADF . System B : System B consists of a proposed septic tank and leach field. The proposed system is designed to service the proposed multipurpose building only, building H. The buildings flowrates consist of daily student flows and occasional event flowrates . 1 . Unit Flowrate Per Person = 10 gal/person/day 2 . Building H Event Hourly Flowrate = 200 gal/hour 3 . ADF = 955 gal/day a. Building (H) Typical School Daily Flowrates i . Total = (2 Staff + 60 Students) * 10 gal/person/day = 620 gal/day b . Building (H) Event Flowrates i . MDF = 200 gal/hour * 3 hours/event = 600 gal/event