§ 156.127. Stormwater Management; System Design.

(A)

General Requirements. All subdivision improvements shall include comprehensive drainage facilities for positive drainage and shall be prepared by a Florida registered engineer. Open swales, ditches or other waterways shall require complete engineering design data pertinent to its design and its effect within the particular drainage area to establish its adequacy by the City Engineer.

(B)

Pipe Materials Permitted. Pipe shall be Class-3 reinforced concrete with patented rubber gasketed joints and shall be designed and installed in accordance with the manufacturer's specifications. Subject to acceptable soil and ground water conditions, corrugated aluminum pipe may be considered, provided the minimum cover from top of pipe to the top of subgrade at any point under a roadway shall meet the manufacturer's specifications. The minimum diameter of any pipe utilized for any portion of an enclosed drainage system shall be fifteen (15) inches.

(C)

Inlets, Manholes and Junction Boxes.

(1)

A pipe shall extend through walls flush with inside wall. Concrete shall be constructed around them neatly. All surfaces shall be plastered so as to prevent leakage. Water-stop materials are recommended. Plastered areas should not crack and be properly prepared to bond the old surfaces. Paved inverts are required. For all concrete structure, all fins and irregular projections shall be chipped off flush with the surface immediately following the removal of forms. All projecting wires and nails shall be cut off at least one-half inch under the surface. All cavities produced by metal spacers, form ties, bolts, honeycomb spots and the like, shall be carefully cleaned, saturated with water and then carefully painted with mortar. All construction and expansion joints in the completed work shall be left carefully tooled and free of mortar and concrete. Joint filler shall be left exposed for its full length, with clean edges. Mortar topping for upper horIzontal surfaces shall not be used. For all concrete surfaces which are to receive a surface finish, the contractor shall remove the forms and finish the concrete immediately after the concrete has set sufficiently. Minimum manhole diameters for intersecting pipe sizes shall be as follows:

Equivalent Pipe Diameter	Inside Diameter
Up to 27 inches	4 feet
27 inches to 36   inches	5 feet
42 inches	6 feet
48 inches	Special design
Larger	Special design

 

(2)

Inlets shall be spaced in such a manner as to accept one hundred (100%) percent of the design runoff. The actual required spacing will depend on the characteristics of each particular site.

(3)

Computation for drainage culverts, ditch sizes and inlet spacing shall be based on the storm frequency as required by the Port St. Lucie Engineering Department and shall be submitted to the City Engineer for approval.

(D)

Underdrains. In cases where there is a prevalence of soils that exhibit adverse water table characteristics, underdrains and/or fill or other acceptable alternative that will provide necessary measures to maintain the structural integrity of the road will be required. The determination of need shall be made by reference to applicable portions of the most recent edition of Soil Survey and Supplement for St. Lucie County, Florida, as prepared by the U.S. Department of Agriculture, and in other publications of the Soil Conservation Services, the Soil Survey Supplements, or whatever subsequent authoritative soil survey may be published for St. Lucie County after adoption of this chapter, or according to information generated by developers.

(1)

Wherever road construction or lot development is planned in areas of the proposed subdivision having soil types with unacceptable water table characteristics, underdrains and/or fill shall be provided and shown on the engineering plans. Underdrains must be designed with free gravity outlet at carefully selected discharge points. Erosion control measures shall be provided as needed at all discharge points.

(2)

Wherever roadcuts in otherwise suitable soils indicate that the finish grade will result in a road-surface-to-water-table relationship that adversely exceeds the degree of limitation stated above, underdrains or other acceptable alternative that will provide necessary measures to maintain the structural integrity of the road will be required.

(3)

Wherever roadway construction reveals unexpected water bearing strata that would cause deterioration of the pavement, underdrains or other acceptable alternative that will provide necessary measures to maintain the structural integrity of the road will be required even though not shown on the plans.

(4)

Filtering media shall consist of stone, gravel or slag, and shall contain no friable materials.

(5)

Wherever underdrain pipe is required, the specifications shall be in accordance with the American Society for Testing and Materials Designation: D3033-5.

(Ord. 94-7, passed 3-14-94)