§ 18-11. Roadway and driveway drainage.

(a)

The drainage of all roadways and driveways shall meet the criteria set forth in this section.

(b)

Roadway ditches and swales:

(1)

Minimum gradient shall be one-tenth (0.1) percent, or the minimum required to provide for the design flow, whichever is greater.

(2)

Maximum gradients shall be determined from soil characteristics. Ditch erosion protection shall be provided as specified herein.

(3)

Ditch protection: Unless otherwise required by the city, the following will be standard ditch protection:

Ditch Gradient	Ditch Side Slopes	Protection Required	Maximum Velocity 10-Yr. 24-Hr. Storm
Less than 1.0%	Less than 1:3	Grassing and mulching	2 FPS
1.0%—1.99%	1:3—1:2	Sodding	4 FPS
2.0% and greater	Greater than 1:2	Ditch paving	4 FPS

 

(c)

Side drains for roadway ditches:

(1)

Placement. Side drain pipe shall be placed in the flow line of the proposed roadway swale with an invert elevation three-tenths (0.3) feet below the proposed flow line.

(2)

Construction details. A schedule showing the size, type and invert elevation side drain needed to gain entrance to each project lot shall appear in the project construction plan.

(d)

Minimum pipe diameter:

(1)

Minimum pipe diameter shall be as follows:

Type	Minimum Diameter
Cross drain	15 inch or equivalent
Side drain	15 inch or equivalent
Underdrains	6 inch

 

(2)

Underdrains may not be used for retention/detention of stormwater unless specifically approved by the city public works department.

(e)

Materials. The following pipe materials are acceptable:

(1)

For cross and side drains:

a.

Reinforced concrete pipe.

b.

Corrugated steel pipe and pipe arch, galvanized and asphalt coated.

c.

Structural plate steel pipe and pipe arch, galvanized and asphalt coated.

d.

Corrugated clad aluminum pipe and pipe arch.

e.

P.V.C. or corrugated polyethylene pipe.

(2)

All pipe shall be provided with mitered ends where exposed . Miter may be included in the pipe or with a separate approved tapered head wall. All corrugated pipe ends shall be protected with concrete slabs as shown in FDOT Design Standards, latest edition. Cross bars shall be installed on all culverts thirty (30) inches diameter and larger. Workmanship and pipe materials shall conform to FDOT Standard Specifications, latest edition.

(f)

Length. The minimum length of pipe to be used (including miter) shall be:

(1)

For road crossings at intersections—from center line of swale to centerline of swale—less forty-eight (48) inches.

(2)

For driveways:

Invert Depth	Minimum Length
	Mitered	w/Headwall
20 inch—40 inch below driveway	50 ft.	40 ft.
Over 40 inch below driveway	60 ft.	50 ft.

 

(3)

All inverts shall be set by a registered surveyor to city approved grades.

(4)

The maximum length of pipe to be used without an access structure shall be:

Pipe Size (in inches)	Maximum Length
15	100 ft.
18—36	300 ft.
42 and larger	500 ft.

 

(5)

All culvert pipes must be joined as directed in FDOT Standard Specifications, and/or Design Standards, latest edition. Minimum cover shall be twelve (12) inches unless otherwise approved. The invert depth and diameter of all culverts shall be approved by the city and set to city specified grade.

(6)

In the event any existing culvert is found to be installed to incorrect grade, or is found to be damaged or is found to be of insufficient capacity, the city shall notify owner and developer in writing, and said culvert shall be replaced at the expense of the owner and developer, within thirty (30) days.

(g)

All swales and drainage facilities located within the city right-of-way are the property of the city. No fencing, shrubs, trees or construction other than grassing may be placed on the right-of-way without city approval.

(h)

Construction and maintenance for driveway crossings of city swales or ditches shall be the responsibility of the individual owner. No person may block or impede the flow of water through any city or private drainage system, nor may leaves, trash or the materials to be placed in or burned in city drainage facilities.

(i)

If swale crossing does not include a culvert, the driveway portion of swale must be paved with a minimum of four (4) inches of reinforced three thousand (3,000) PSI concrete with low line at design grade. In some instances, other flow lines may be established for water retention. These systems must be approved in advance by the city public works department.

(j)

In the event any swale paving is found to be installed incorrectly or the swale must be modified in cross section, the city will remove the swale paving and the owner and developer will be required to replace the paving to the new grade or to install a culvert, at the owner's and developer's option and expense.

(k)

Bridges and box culverts shall be designed and constructed in accordance with Florida Department of Transportation standards.

(l)

Development activities shall not be approved unless there is sufficient available capacity to sustain the level of service for the drainage system to set forth in section 4.01.04 of the Land Development Code.

(Ord. No. 16-02, § 1, 5-9-16)