3631 WETMORE AVE 2020-05-06 - Laserfiche WebLink

April 12,2018 Page 4 of 5 Retaining Wall Design the wall. In addition,a drainage collector system consisting of 4-inch perforated PVC pipe should be placed behind the wall to provide an outlet for any accumulated water. The wall drains should outfall through the base of the wall at each end. East Retaining Wall The existing concrete retaining wall along the east property line is tipping between 3 and 6 inches toward the east. This wall is 3 to 7 feet tall and there are concrete panels above the wall area. The wall is about 33 feet long with a short return wall at the north end. The south end terminates at the garage wall. It is our opinion that the wall is capable of providing ongoing support to backfill and surface materials; however,we recommend filling an approximate 1-inch wide gap between the wall and parking area west of the wall. This will help reduce water intrusion that is likely causing the slow tipping of the wall. The gap should be fully filled with a waterproof outdoor rated concrete-acrylic caulk or other material rated for exterior use. We estimate that this wall may last another 15 years provided periodic maintenance of the gap is performed. Erosion and Sediment Control Erosion and sediment control (ESC) is used to reduce the transportation of eroded sediment to wetlands,streams, lakes, drainage systems,and adjacent properties. Erosion and sediment control measures should be implemented and these measures should be in general accordance with local regulations. At a minimum, the following basic recommendations should be incorporated into the design of the erosion and sediment control features for the site: • Schedule the soil, foundation, utility, and other work requiring excavation or the disturbance of the site soils, to take place during the dry season (generally May through September). However, provided precautions are taken using Best Management Practices (BMP's), grading activities can be completed during the wet season (generally October through April). • All site work should be completed and stabilized as quickly as possible. • Additional perimeter erosion and sediment control features may be required to reduce the possibility of sediment entering the surface water. This may include additional silt fences, silt fences with a higher Apparent Opening. Size (AOS), construction of a berm, or other filtration systems. • Any runoff generated by dewatering discharge should be treated through construction of a sediment trap if there is sufficient space. If space is limited other filtration methods will need to be incorporated. (q/