A. Prior to the construction of street or alley surfaces and pavements, adequate drainage facilities shall be installed by the subdivider, according to plans furnished by the subdivider prepared by a registered professional engineer or a registered land surveyor and approved by the Commission. A storm drainage analysis based upon a ten (10) year return period shall be used as the basis for the drainage system. A copy of the analysis is to be submitted to the Commission with the drainage facility plans. Pipe used for drainage shall be of coated corrugated metal, concrete or vitrified clay or other approved material of an approved design, size and strength to meet the requirements of the specific conditions which may be encountered. Minimum diameters of pipe to be used shall be as follows:
1. Roadway cross drains, 12 inches.
2. Entrance culverts, 12 inches.
3. Perforated under-drains, 8 inches.
B. Upon completion of the street improvements, a minimum of two (2) sets of as-built plans and profiles shall be filed with the Commission.
C. It is the authority of the county surveyor to sign off on all drainage issues regarding all county regulated drains.
D. Indiana Drainage Code Requirements:
1. 75-Foot Drainage Right-Of-Way. The Indiana Drainage Code provides that all regulated drains in the State of Indiana shall have a seventy-five foot (75) right-of-way on either side of the centerline of any tiled drain and from the top edge of each bank of an open ditch as determined by the Hancock County Drainage Board. This right-of-way is for the use of the Hancock County Surveyor or an authorized representative of the Surveyor.
2. Use of Drainage Right-Of-Way. The owners of land over which the right-of-way runs may use the land in any manner consistent with the Indiana Drainage Code and the proper operation of the drain. Permanent structures may not be placed upon or over the right-of-way without the written consent of the Hancock County Drainage Board. Temporary structures may be placed upon or over the right-of-way without written consent of the Hancock County Drainage Board but shall be removed immediately by the owner when so ordered by the Hancock County Drainage Board.
E. Swales.
1. The minimum slope of flow line of swales is one percent.
2. Swales with steep slopes must have sufficient energy dispersing dams to prevent erosion control.
3. Swales longer than four hundred (400) feet must have a paved invert along the total length of the swale.
4. All backyard swales shall have subsurface drains.
F. Storm Sewer Construction Specifications.
1. All storm sewers will have a minimum cover of two (2) feet.
2. Storm sewers will have a minimum velocity of two and one half (2.5) feet per second and a maximum velocity of fifteen (15) feet per second.
3. The maximum distance between storm structures on pipes from twelve (12) to Forty-two (42) inches in diameter shall be four hundred (400) feet.
4. The maximum distance between storm structures on pipes is forty-eight (48) inches and large shall be six hundred (600) feet.
5. Storm water may not run along a gutter more than four hundred (400) feet to a street inlet.
6. Storm inlet openings shall be designed for a ten (10) year flow rate assuming a fifty (50) percent clogged inlet. Adequate overflow shall be provided (See Detail 410-03).
7. All storm sewers shall be bedded in #8 (eight) stone.
8. References.
a. ANSI/ASTM D698 - Test Methods for Moisture-Density Relations of Soils and Soil-Aggregate Mixture, using 5.5 lb. (2.49 kg) Rammer and 12-inch (304.8 mm) drop.
b. ANSI/ASTM D1557 - Test Methods for Moisture-Density Relations of Soils and Soil-Aggregate Mixtures using 10 lb. (4.54 kg) Rammer and 18-inch drop.
c. ANSI D3017 - Test Methods for Moisture Content of Soil and Soil-Aggregate Mixtures.
d. Indiana Department of Transportation (INDOT) Current Specifications.
9. Definitions.
a. Bedding: Fill placed under, beside and directly over pipe, prior to subsequent backfill operations.
10. Submittals.
a. Manufacturer's Certificate: Certify that products meet or exceed specified requirements.
11. Project Record Documents.
a. Submit as required by Engineer.
b. Accurately record actual locations of pipe runs, connections, manholes, catch basins, and invert elevations.
c. Identify and describe unexpected variations to subsoil conditions or discovery of uncharted utilities.
12. Regulatory Requirements.
a. Verify that field measurements and elevations are as indicated.
G. Products.
1. Sewer Pipe Materials.
a. Reinforced Concrete Pipe: Concrete pipe shall conform to current ASTM Specifications C-14, C-76, and shall be of proper class and ASTM designation as shown on the plans and details.
b. PVC Pipe: PVC pipe shall conform to the requirements of ASTM C3033 or D3034, D1784, with an SDR of 35, and a compound designation class No. 12454 or as shown on the plans. PVC pipe shall meet AASHTO M304 with a 46 psi minimum rating.
c. ADS –12 or Hi-Q pipe shall conform to ASHTO classification "Type D". Pipe and fitting- shall be made with virgin Polyethylene compounds which conform with the requirements of cell class 324420C as defined and described in ASTM D3350.
2. Joints and/or Couplings.
a. Reinforced Concrete Pipe Joints: Joints shall be flexible rubber-gaskets conforming in every respect, and in strict accordance with the current ASTM designation C-443. The method of coupling the pipe shall be in strict accordance with the gasket manufacturer's recommendations.
b. Poly Vinyl Chloride Pipe Joints: Poly vinyl chloride pipe joints shall be bell and spigot with elastomeric rubber gasket, as recommended and supplied by the pipe manufacturer.
c. Polyethylene pipe shall use a bell and spigot coupling meeting ASTM F477 specifications with a o-ring type gasket assembly.
d. Catch Basins: Precast concrete catch basins shall conform to current ASTM Specifications for reinforced concrete sewer pipe, and shall be of size, type and location as shown on the plans and details (See Detail 410-02).
e. Iron castings shall conform to the current ASTM Specifications for gray iron castings, class 20 and shall be as shown on the plans and details. All castings shall be true to pattern in form and dimension: Free from faults, sponginess, cracks, blow holes and other defects. Bearing surfaces between cast frames, covering and grates shall be machine fitted together and match marked to prevent rocking.
f. All frames shall be placed in a 2-inch mortar bed and set to proper alignment and grade.
g. Catch basin steps shall be manufactured so as to resist corrosion, materials will be plastic coated steel. Steps shall have a minimum 10-inch tread width and shall project a minimum of 5 inches from the face of the wall. Steps shall be placed either at 12-inch intervals in a straight line and mortared in with a 1:2 cement mortar.
h. A 1:2 cement mortar grout fillet shall be placed around the joint to seal the frame to the structure once the frame inside the catch basin has been properly set.
i. Precast concrete blocks shall conform to current ASTM Specifications C-139 for concrete manhole and catch basin blocks.
j. Base Pad: Cast-in-place concrete of type specified in Section 03300. Minimum thickness of 6 inches, leveled top surface or shall be a precast base and conform to ASTM Specifications C-76 and/or C-478.
k. Bedding Materials: As specified in the current addition of INDOT Standard Specifications.
3. Execution.
a. Examination.
1. Verify that excavation base is ready to receive work and excavations, dimensions and elevations are as indicated on drawings.
b. Preparation.
1. Hand trim excavations to required elevations. Correct over excavation with course aggregate.
2. Remove large stones or other hard matter which could damage piping, or impede consistent backfilling or compaction.
c. Bedding.
1. Excavate pipe trench in accordance with Section 02225 for work of this section. Hand trim excavation for accurate placement of pipe to elevations indicated.
2. Place bedding material at trench bottom, level materials in continuous layer not exceeding 6 inches compacted depth.
3. Maintain optimum moisture content of bedding material to attain required compaction density.
d. Installation - Pipe.
1. Install pipe, fittings, and accessories in accordance with applicable standards for type of pipe used and manufacturer's instructions. Seal joints watertight.
2. Place pipe on minimum 6-inch deep layer of bedding (PVC only).
3. Lay pipe to slope gradients noted on drawings true to line starting at the outfall end of the sewer and laying the pipe with the bell end upgrade.
4. The sections of the pipe shall be so laid and fitted together that, when completed, the sewer will have a smooth and uniform invert.
5. The pipe shall be kept thoroughly clean so that jointing compounds will adhere and after laying each pipe, the interior of the pipe shall be free from all dirt, cement, or superfluous material of every description so as to leave a clean, smooth, continuous flow line in the pipe.
6. Install aggregate bedding by hand from bottom of trench to a horizontal plane passing through the center of the pipe with bedding material placed in layers of 3 inches and compacted by tamping.
7. From a horizontal plane passing through the center of the pipe to a point 1-foot above the top of the pipe, the trench shall be backfilled with bedding material, placed in 6-inch layers and compacted to 95 percent of maximum dry density as determined by the Modified Proctor Method.
e. Installation - Catch Basins (See Detail 410-02).
1. Form bottom of excavation clean and smooth to correct elevation.
2. Form and place cast-in-place or precast concrete base pad, with provisions for storm sewer pipe and sections.
3. Level top surface of base pad to receive concrete shaft sections, sleeved to receive storm sewer pipe sections.
4. Establish elevations and pipe inverts for inlets and outlets as indicated.
5. Mount lid and frame level in grout, secured to top cone section to elevation indicated.
f. Field Quality Control.
1. Request inspection prior to and immediately after placing aggregate cover over pipe.
2. Testing shall be considered a part of the Contractor’s cost for backfill and compaction.
3. Compaction testing will be performed by a certified testing laboratory and shall be to 95 percent dry density.
4. If tests indicate work does not meet specified requirements, remove work, replace and retest at no cost to Owner.
g. Protection.
1. Protect pipe and aggregate cover from damage or displacement until backfilling operation is in progress.
H. Detention Ponds.
1. All ponds shall be constructed with a safety ledge beginning at two and one half (2 ½) feet below normal pool elevation. The safety ledge shall have a maximum slope of 1:10. The safety ledge shall be a minimum of 10 wide.
2. Bank slopes able the normal pool elevation shall have a maximum slope of 6:1 (see Detail 423-01 in the Appendix).
3. Erosion control measures shall be installed to prevent bank erosion.
4. All dry hydrants in association with the required detention facilities shall be installed consistent with the standards established by the Hancock County Soil and Water Conservation District, including, but not limited to, the installation of a 5 inch Storz connection.
(Am. Ord. 110219, passed 11-2-2019)