1122 75TH ST SW 2018-01-02 MF Import

In addition, all type ii catch basins and manholes with "catches'� are required to have locking lids. These requirements should be indicated on the plans, either specifically for each structure of this type or as a general note. Wetland nerc oipe detail This pipe does not appear to be on the plans, or at least, is not labeled as such. No calculations are given as to how much water is going to the perc. pipe, when, or what water. If this system is intended to maintain wetland B's hydrology, these calculations must be submitted and compared to existing flows to wetland B. Is water from the pond intended to feed continuously into this system? The invert elevation of catch basin 52 is qiven as 2.5 feet below Y.he permanent water level in the pond, although it is difficult to tell what the elevation of the perforated pipe is along its length. The elevation of the perc pipe system should be related to the elevation of the ground water table in the area. There should probably be enough head ava�lable upstream of the system to cause water to overflow the top of the rock-filled trench and sheet flow to the wetland if water doesn't infiltrate out as planned due to high groundwater or clogging of the system. It might be preferable to set the perforated pipe closer to the surface of the trench, to facilitate movement of water out of the system by sheetflow to the wetland if infiltration fails to occur. To minimize the fines brought in, "minus" material shouldn�t be specified for the pere system. A minimum diameter should be specified for the washed rock. The trench should be lined with an appropriate filter fabric material to prevent movement of fines into the trench from surrounding material. iscellaneous• When perforated pipe is called out, the type of pipe, size of perforations and spacing of perforations must be called out. A small asphalt berm or lip should be constructed at catch basins 37 and 38 to ensure that runoff from the upper area