§ 2.05. Storm[water] and groundwater drainage.

(a)

Installation, capacity. In a subdivision, storm drainage facilities shall be installed by the developer, which the city engineer certifies as adequate to handle a minimum rainfall of three inches in an hour without damage to the facilities. Where excess capacity is required to handle the needs of the general storm drainage system, costs of such extra capacity shall be prorated between the developer and other interests in a manner acceptable to the city.

(b)

Subdrains in wet soil. Subdrainage facilities may be required in wet-soil areas if the city engineer determines that the bottom of any base material used for foundations or streets would otherwise be less than one foot above the highest anticipated groundwater levels. Subdrains shall be in accordance with standards set by the city engineer and may empty into a storm sewer system or any other outlet approved by the city engineer.

(c)

Requirements for underground structures. Underground drainage structures shall be sized either by the Kutter or Manning formula with due allowance for sanding, maintenance, velocities, etc. The following types of materials will be acceptable as minimum for underground drainage structures and outfalls:

(1)

Culverts.

a.

Pipe. Galvanized corrugated metal pipe, pipe arch, or concrete pipe.

b.

Headwalls. Cast concrete.

(2)

Storm sewers.

a.

Pipe. Asphaltic bonded corrugated metal, concrete or vitrified clay.

b.

Manholes. Cast concrete bottoms, brick walls, cast iron rings and covers.

c.

Side inlets. Cast concrete bottoms, brick walls, cast iron cover or concrete top with cast iron cover and ring.

d.

Drop inlet. Same as side inlets with cast iron gate.

e.

Size. The following minimum sizes are set up for storm sewers:

1.

For gravity line from drop or side inlet structure to storm sewer or outfall, 12 inches I.D.

2.

For gravity storm sewer, 15 inches I.D.

(3)

Subdrains. It is required that the lowest elevation of the bottom of the base material be installed at a minimum elevation of one foot above any groundwater, and in wet-soil areas the city requires the submission of a groundwater contour map, showing soil profiles and the proposed street grades. The groundwater elevation may be lowered by the use of subdrains on one or both sides of the street as required. Subdrains may empty into a storm sewer system, or other approved outlet.

a.

Subdrains shall be of open-joint vitrified clay sized as required.

b.

The rock surrounding the open-joint pipe shall be no. 16 modified (F.S.R.D. specifications) slag at least 20 inches deep and 12 inches wide.

(4)

Drainage outfalls. All surface drainage subdrain discharges must be into a lake, canal, creek or other waterway capable of receiving the flow. Adequate plans, maps, or other detailed information must be submitted showing the final disposal of all stormwaters, where the stormwaters are not disposed of within the limits of the area drained. Disposal of stormwaters into existing drainage facilities, not controlled by the city, will be acceptable only if prior written approval is obtained from the controlling agency, e.g., the state department of transportation, A.C.L. R.R. and others.

(Code 1988, § 19-155)