CORRESPONDENCE_1982-1983 - Laserfiche WebLink

Home Browse Search

August 8, 1983 Project 116-1.4 _ 3 _ D. LEACHATE COLLECTION SYSTEM Since the leachate collection sump and riser pipe have already been installed, we would request permission to utilize this sump. In order to do so we will be required to place additional fill material in the northeast corner of the trench sloping toward the sump and collection system. This will offset the overall floor slope to the north and east. We feel that it would be more economical to place a sloping fill in the northeast corner of the trench than to relocate the entire sump facility. The leachate floor drain to be placed along the eastern wall of trench #4 will be directed toward the sump with a gradual curve to permit passage of clean-out equipment, if necessary. The approximate curve to be utilized in construction of this facility is shown in the drawing on plate 1. We have inquired with several manufacturers of PVC pipe and find that for our purposes, Schedule 40, 4" PVC pipe will be most appropriate for our needs. This 4 inch schedule 40 pipe has a crush strength in excess of 150 lbs/sq.in. If one assumes that the filter material around the pipe bears no load of the overlying waste and cover material, we calculate that 25 feet of FMC waste and 3 feet of compacted cover will impose approximately 2860 pounds downward pressure per cubic foot. This amount to 19.8 lbs/sq.in. total over-burden load (assumes 25 feet thickness of waste @ 100 lb/cu. foot and 3 feet thickness of compacted cover material @ 120 lbs/cu.ft.). Three lines of 1/4" perforations will be placed in the pipe in accordance with the detail on Plate 2. According to the manufacturing spec's. , this will not materially affect the bearing capacity of the pipe. We were not able to acquire printed engineering specifications on 4" PVC pipe however, this data is available from the manufacturer located in Chicago, Illinois if it is required by your staff. The upper end of the drain pipe and the clean out will be protected from being plugged by waste material so that the drain can easily be entered for cleaning if necessary. The pipe will also be capped. The detail is shown on Plate 2. In order to resolve the discussion pertaining to the filter material surrounding the drain line and the drainage blanket on the trench floor. We propose the following. Place a 6" lift of Class 2 permeable (Caltrans Standard Specification #68) over the entire operations area at the north end of trench A. The same material will be placed in the drainage trench surrounding the 4" perforated PVC pipe. This GBeta Associates Q