Generally, no catch basin lead invert shall be less than three feet, six inches below the top of the grate. Storm sewers, generally, shall be kept at a depth of five feet below the finish grade to minimize conflict with gas and water mains. The maximum depth of pipe shall be in accordance with the recommendations of the Portland Cement Association and as specified by the Division of Water. These recommendations, which are based on the quality of pipe, soil conditions, trench widths, dynamic loads and bedding conditions, shall be strictly adhered to.