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OCT 3 11985 BOOK 62 PnE 59® Given the differences in conditions among single-family building sites in the County, it is not possible for the County to determine specific drainage improvements which would be applicable to all lots in the County. There are, however, a number of possible site improvements which could be made to a lot in order to prevent stormwater discharge to adjacent property. These include development of swales, use of roof drains, installation of a french drain system, and innovative site/building design. It is the staff's position that the applicant should be responsible for designing a drainage system that prevents runoff from his lot from impacting adjacent property. The staff also feels that submittal of the conceptual drainage design should be a building permit application requirement. In this way the staff can review the proposed system concur- rent with its review of the applicant's building plans, and the staff can assess its adequacy before the house is built and the applicant's options are more limited. While such a conceptual drainage plan would not need an engineer's certi- fication, it would have to indicate general finished ele- vations, grade transitions to abutting property, proposed drainage improvements, and other pertinent information. With this system, the conceptual drainage plan could be reviewed by the Public Works Division as part of the overall building permit review function. Since this analysis would not have to be detailed or extensive, it could be conducted in conjunction with the right-of-way examination of the building permit application. A final site inspection could be done in conjunction with the building department's final inspection, and construction of the drainage system as depicted on the conceptual drainage plan would be a require- ment for obtaining a certificate of occupancy. To establish a procedure as discussed herein, the staff recommends that the Board of County Commissioners amend the zoning code to prohibit stormwater discharge from sin- gle-family lots to adjacent property and to mandate submittal of a conceptual drainage plan as part of a single-family building permit application when deemed necessary by the public works director. The staff specifically suggests that the General Provisions Section of the zoning code be amended to establish Section 25S. That section should read as follows: 25.S STORMWATER DISCHARGE FROM SINGLE-FAMILY LOTS No stormwater discharge in excess of predevelopment rates from single-family lots to abutting property shall be allowed. To ensure that stormwater runoff is adequately managed, each applicant for sin- gle-family home building permit approval shall, if deemed necessary by the public works director, submit a conceptual drainage plan depicting the proposed stormwater management system, including swales, finished elevations, transition grades to abutting property, any off-site tributory drainage entering the property, proposed drainage system improvements, and other pertinent information required by the public works director. No certifi- cate of occupancy shall be issued where improve- ments depicted upon a conceptual drainage plan have not been constructed. 4