§ 42-25. Requirements for storm drainage on streets with curb and gutter.

(a)

Location of storm sewers. Storm sewers shall not be placed under concrete pavement unless specifically authorized; when authorized to be placed under concrete pavements, the excavation shall be backfilled with cement stabilized sand, 1-1/2 sacks of cement per cubic yard of sand.

(b)

Gutter grades.

(1)

Minimum longitudinal gradient on gutters shall be 0.40 percent minimum.

(2)

When a curb and gutter section intersects a drainage ditch, the grade of the gutter shall be above the design water surface of the ditch.

(c)

Inlets. Inlets shall be spaced based on a ten-year intensity rainfall. Inlets shall be spaced so that the pondage width shall not exceed one-half of a lane width. All drainage structures, including but not limited to: curb inlets, grate inlets, junction boxes, etc., shall be site built. Pre-cast structures will not be allowed.

(d)

Design. The storm sewer shall be designed to be able to carry the design discharge of a five-year intensity rainfall.

(e)

Types of pipe. The following types of pipes shall be allowed in construction of the subdivision:

(1)

Reinforced precast concrete pipe.

(2)

Smooth interior corrugated double-gasketed polypropylene pipe.

(f)

Drain preparation. All lots inside each new subdivision shall be prepared that they drain to the front of the lot to the nearest drain on the street, as determined by the city engineer. The city inspector must inspect and approve that the drainage has been properly done, before a certificate of occupancy will be issued.

(g)

Pipe backfill. All aluminized steel and polyethylene pipe shall be backfilled with cement-stabilized sand (2 sack/cy) in accordance with manufacturer's recommendation. All aluminized steel pipe joints shall be wrapped with filter fabric. All polyethylene pipe joints shall be made using a gasket coupling as approved by the city engineer. All pipes shall meet H-20 loadings.

(h)

Storm water detention. Detention of storm water in the amount above the pre-development flow shall be required as calculated for a 25-year event.

(i)

The regulations of this section are inclusive but subordinate to requirements prescribed by the City of Lumberton's Drainage Criteria Manual.

(Ord. No. 05-1162, § 10(G), 3-28-2005; Ord. No. 15-1212, § 2(Exh. 1), 7-13-2015; Ord. No. 15-1215, § 2, 8-10-2015; Ord. No. 16-1222, § 2, 8-8-2016)