(A) Generally. Streets shall be designed to avoid conflicts between storm water conveyance, traffic, parking, pedestrian access, ADA requirements and bicycle traffic.
(B) Standards.
(1) Streets draining a watershed greater than 100 acres must be designed for the 100-year frequency storm.
This “rain garden” in Carpenter Village (Mooresville, North Carolina) drains three acres with underground rain storage and provides passive open space as part of a public green.
(2) Streets may be used for storm water drainage only if the calculated storm water flow does not exceed the flows outlined in Table 153.1065(A) of this chapter or the velocity does not exceed ten feet per second.
(3) Where streets are not capable of carrying storm-waters, inlets or curb openings discharging to drainage channels or storm sewers shall be provided. Partial flow past the inlet will be allowed when the capacity of all downstream street systems can accommodate the flow.
(4) Street width shall not be widened beyond the width as determined by the street classification for drainage purposes.
(5) Storm water conveyance on streets shall be designed to account for the cumulative impact of peak flows and run-off volumes on the system as it progresses downgrade.
(6) Curb cuts for driveways on all streets shall be designed for compatibility with the storm water conveyance function of streets.
(7) Potential flooding problems or conflicts at the connection points where new or modified drainage systems (including streets and storm sewers) and the existing portions of the downstream street system and storm water conveyance system shall be identified and resolved, either in the design of the new or modified drainage system or in modifications to the existing system.
(8) Dwelling units located on the downhill side of a T-intersection with a street or drainage channel discharging onto the intersection shall be sited in order to avoid obstruction of the drainage patterns.
(C) All-weather crossings. Where streets cross existing or proposed watercourses, all-weather crossings are required. Culverts or bridges shall be adequate to allow passage of the design storm identified in § 153.1037 of this chapter.
(D) Standards by street classification. The storm water capacity for streets shall conform to Table 153.1065(A) and Table 153.1065(B) of this chapter.
(Ord. 3020, passed 9-10-2013, § 5.22.14)