1 i l COMMISSIONERS' COURT AGENDA REQUEST PLEASE FURNISH ONE ORIGINAL AND NINE COPIES OF THIS REQUEST AND DOCUMENTS TO BE REVIEWED BY THE COURT. MADE B Jonathan Letz OFFICE: Commissioner, Pct. 3 MEETING DATE: Apri125, 2005 TIME PREFERRED: SUBJECT: Consider and discuss Subdivision Rules and Regulations. EXECUTIVE SESSION REQUESTED: (PLEASE STATE REASON) NAME OF PERSON ADDRESSING THE COURT: Commissioner, Pct. 3 ESTIMATED LENGTH OF PRESENTATION: IF PERSONNEL MATTER -NAME OF EMPLOYEE: Time for submitting this request for Court to assure that the matter is posted in accordance with Title 5, Chapter SS I and 552, Government Code, is as follows: Meeting scheduled for Mondays THIS REQUEST RECEIVED BY: THIS REQUEST RECEIVED ON: 5:00 P.M. previous Tuesday. All Agenda Requests will be screened by the County Judge's Office to determine if adequate information has been prepared for the Court's formal consideration and action at time of Court Meetings. Your cooperation will be appreciated and contribute towards you request being addressed at the earliest opportunity. See Agenda Request Rules Adopted by Commissioners' Court. Draft 042505 A 5.06 Drainage: 5.06.A All drainage plans, drainage calculations, drainage structures designs, drainage facilities designs and all other requirements of this section shall be prepared by a registered professional engineer experienced in hydrology analysis, and shall be signed and sealed by the registered professional engineer licensed in the State of Texas. The registered professional engineer shall review the installation and construction of all drainage facilities and insure that such installation and construction was done in substantial accordance with the specifications contained therein. The registered professional engineer or the developer shall certify on the final plat that all drainage requirements specified by the registered professional engineer were constructed substantially in accordance with all design criteria submitted and are in compliance with Kerr County Subdivision Rules and Regulations. (See Appendix M) 5.06.B Subdivision design, layout and construction shall be done to minimize any adverse impact to private property, public property, all easements, and all public or private right-of--way either within or outside the proposed subdivision. Provisions must be made to assure that no adverse impact is made to existing drainage systems within public right of ways. 5.06.C (1) Subdivision drainage calculations for subdivisions with minimum lot size of five (~ acres or greater. The calculated post-construction runoff rates at the point of flows leaving the subdivision for each drainage basin shall be calculated based on the area of the pre-development drainage basin plus any added or subtracted azea due to subdivision construction or layout. All runoff rate flow calculations shall be done in feet per second (fps). The runoff rate shall be calculated for the five (5), ten (10) and one-hundred (100) yeaz storm frequency, respectively. (a) If the pre-development drainage basin area is five (5) acres or less, the calculated post-construction runoff rates at the point of flow leaving the subdivision shall not exceed a twenty percent (20%) increase in the maximum flow for the drainage basin for each calculated storm frequency. (b) If the pre-development drainage basin area is greater than five (5) acres and less than twenty-five (25) acres, the calculated post- construction runoff rates at the point of flow leaving the subdivision shall not exceed a ten percent (10%) increase in the maximum flow for the drainage basin for each calculated storm frequency. (c) If the pre-development drainage basin area is twenty-five (25) acres or greater, the calculated post-construction runoff rates at the point of flow leaving the subdivision shall not exceed the pre-construction runoff rate for the post-construction drainage basin for each calculated storm frequency. (d) Drainage channels, storm sewers, retention structures or other devices shall be constructed to maintain the flow rates set forth in (1), (2) or (3) above. Vegetative improvements may be considered in calculating the runoff rates within a drainage basin (2) Subdivision drainage calculations for subdivisions with minimum lot size of less than five (5) acres. `The calculated post-construction runoff rates at the point of flows leaving the subdivision for each drainage basin shall be calculated based on the area of the pre-development drainage basin plus any added or subtracted area due to subdivision construction or layout. All runoff rate flow calculations shall be done in feet per second (fps). The runoff rate shall be calculated for the five (5), ten (10) and one-hundred (100) year storm frequency, respectively. (a) If the pre-development drainage basin area is five (5) acres or less, the calculated post-construction runoff rates at the point of flow leaving the subdivision shall not exceed a ten percent (10%) increase in the maximum flow for the drainage basin for each calculated storm frequency. (b) If the pre-development drainage basin area is greater than five (5) acres and less than twenty-five (25) acres, the calculated post- construction runoff rates at the point of flow leaving the subdivision shall not exceed a five percent (5%) increase in the maximum flow for the drainage basin for each calculated storm frequency. (c) If the pre-development drainage basin area is twenty-five (25) acres or greater, the calculated post-construction runoff rates at the point of flow leaving the subdivision shall not exceed the pre-construction runoff rate for the post-construction drainage basin for each calculated storm frequency. (d) Drainage channels, storm sewers, retention structures or other devices shall be constructed to maintain the flow rates set forth in (1), (2) or (3) above. Vegetative improvements may be considered in calculating the runoff rates within a drainage basin 5.06.D The storm drainage plan shall include a prepazed plat to a scale of two hundred feet to one inch (200:1) and with the same contours and scaled lot sizes as shown on the plat. The plan shall indicate both the pre development and post development acreage azeas and run off rates for the required frequencies for each drainage basin in the subdivision. The storm drainage plan shall include all lots, roads and easements. All road widths and grades shall be indicated. Runoff figures shall be indicated on the outlet and inlet side of all drainage ditches and storm sewers; at all points the road changes grade of more than three (3) percent; at all points the road changes direction of less than 120 degrees and where the water enters another road or storm sewer or drainage ditch. Three (3) copies of the plat, the plan and all backup material and calculations shall be submitted to the county. 5.06.E When a drainage channel, storm sewers, retention structure or other device is to be constructed, three (3) copies of the design complete with construction plans, profiles, and specifications shall be submitted. The plans shall show construction details, calculations showing the anticipated storm water runoff, including watershed area, percentage and velocity of runoff, and time of concentration. 5.06.F No pipe less than 18 inches in diameter or comparable flow area shall be used, including driveway crossings. 5.06.G Drainage easements shall be provided as necessary. 5.06.H All drainage structures crossing roads within a subdivision shall be sized based on calculated five-(5) year frequency as established by standard engineering practices. 5.06.I All drainage structure installation and construction shall be inspected and tested during construction to insure installation and construction is in accordance with the approved plans and design. Inspections and testing shall include verification of materials used, compaction tests, grade calculations and other testing requirements as may be required to verify construction. A copy of all testing shall be provided to the county within 30 days of completion of testing .All test results must be submitted prior to final plat approval or shall be covered by letter of credit or performance bond. 5.06.J Subdivisions with a minimum lot size of twenty (20) acres or a total number of lots of less than five (5) shall be exempt from this sections 5.06 C., 5.06.D., 5.06. E.