Permit - 1303147 - Laserfiche WebLink

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existing staked and marked building grades. This point is designated building subgrade and assigned the elevation 194,5' All elevations are computed from this point, iV. SAND FILTER Construction of the sand filter unit shall comply with the enclosed plans and specifications. Details of the construction are attached. Any changes from these plans will be the responsibility of the contractor to have approved by the county sanitarian, The filter is sized to acco~amodate up to 40 employees and is sized at 488 square feet which is approximately 22'1'' square. The sand filter form will be constructed by erecting a plywood frame reinforced with 2"x 4" supports, The plywood forms will be level both vertically and horizontally, A leveling base will be constructed by running 5 1" x 2~ grade boards along the filter Bottom. The boards will be located, one in the filter center, two on the outer edges~ and two halfway between to center and the outer edges. The grade hoards will he parallel and provide a minimum of two inches of slope from the outer edge to the center of the filter for positive drainage. Sand is to he screed to the top of the grade boards and compacted with a water filled lawn roller at least 3 times replacing the sand that has been compacted. Care should be taken to insure no sharp ob}rets protrude from the compacted sand base. A depression will be provided in the filter center as shown on the attached plan to accommodate to Orenco sand filter pump basin. This basin will be provided with a EPO 411 pump and assembly as shown and will pump to the drainfield via a 2" pressure line sch 40 grade, The liner is now fitted into the plywood form avoiding folds and wrinkles where possible. The liner in the filter corners will be folded to the outside of the liner neatly makin~ only one visible fold which is in the corner, The underdraiu which is slotted 4" 3034 pipe is now covered with clea~_~....washed drainroe~ and leveled to the filter sides. The drainrock will be covered with Typar 3201 filter fabric or equivalent. 24" of medium s&nd. meeting sand specifications found in O.A.E. 340-71-100 (?3) will be place over the filter fabric layer, The top of the sand layer will be raked and leveled as well as possible to achieve a level surface of within 1' plus or minus. Certification of the sand specifications will be obtained from lhe supplier and provided to the county sanitarian. AS the sand is placed in the filter container, soil will be backfilled on the outside of the container to the same level as the sand to equalize the pressure and not distort the plywood form. The distribution network will be laid on top of 6" of clean,_