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(A) Storm water drainage.
(1) An adequate system of storm water drainage designed for a ten-year rain shall be constructed and installed consisting of storm sewers, manholes, inlets, catch basins and other necessary facilities that will adequately drain the entire subdivision. Open ditches shall be avoided if possible. The storm water drainage system shall be separate and independent of the sanitary sewer system.
(2) All street pavements in the subdivision shall be provided with drainage inlets discharging directly into a storm sewer system which shall conduct the storm sewer to an established watercourse or outfall sewer. Inlets shall be placed in gutter lines of pavements at all low points at street intersections except when at the high point and at intervals necessary to assure drainage traveling not more than 400 feet in the gutter line where the minimum street grade is used.
(3) (a) Design of storm sewers shall be based on a flow computed on the basis of the rational formula:
Q equals C I A, where:
—“Q” is storm water runoff in cubic feet per second from the drainage area.
—“C” is a coefficient representing the ration of runoff to rainfall. “C” shall not be less than 0.45 in short systems for the average residential area.
—“I” is the intensity of rainfall in inches per hour for a duration equal to the time of concentration. The value of “I” will depend on the rainfall intensity curve for the Northeast Illinois Area in a ten-year frequency.
—“A” is the drainage area in acres.
(b) Provisions must be made in the design of the storm sewer for the runoff which will come on the subject land from tributary lands through natural watercourses. In calculating the runoff from tributary lands, consideration shall be given to the character of the developed land in determining the “C” factor. For undeveloped land the “C” factor shall be no less than 0.35.
(4) All storm sewers and connection pipes between inlets, catch basins and storm sewers which are constructed beneath existing or proposed paving improvements shall be backfilled in lifts with “stone screening” or “trench backfill”, as defined in the state standard specifications. Reinforced R.G.P. pipe shall be used under all pavements. Inlet leads shall be a minimum of 12 inches in diameter.
(B) Sanitary sewers.
(1) A complete system of sanitary sewer lines, including sewer stub terminals at the property lines for each lot, shall be constructed throughout the entire subdivision, with connections to the sewer system serving the village.
(2) All sanitary sewers shall be designed and constructed in accordance with the requirements of the Water Reclamation District of Greater Chicago. The maximum allowable infiltration shall be 500 gal/in./mi/day. The maximum allowable manhole spacing shall be 330 feet.
(3) Where lots cannot, economically or for other reasons, be connected with the public sewerage system, provisions must be made for sanitary sewerage facilities approved by the Village Engineer and the Plan Commission.
(4) The design of sanitary sewer system within a subdivision shall anticipate and provide capacity for all other sanitary sewerage from adjacent lands. The designs shall provide adequate capacity for receiving the sewerage form these area on a basis of the ultimate development of the areas.
(5) All trunk sewers and sewers serving off-site areas shall be in accordance with the Village Master Plan.
(C) Water supply.
(1) All subdivisions within the corporate limits of the village shall be served by an interconnected water distribution system serving all lots with water. This system shall become a part of the village water distribution system. The design of the system shall be in accordance with the requirements of the State Environmental Protection Agency Bureau of Public Water Supply. Construction shall be in accordance with the standard specifications for water and sewer main construction, adopted 8-1-1967.
(2) All lots shall be serviced with an individual water service to the property lines.
(3) All transmission mains and main distribution lines shall be cast iron, in accordance with the Village Master Plan. The system shall be complete with valves and fire hydrants. Maximum hydrant spacing shall be 400 feet.
(4) Where the water supply is not provided in subdivisions with lots with one acre or more in area outside the corporate limits of the village, conclusive evidence shall be presented by the subdivider, on the basis of suitable tests and surveys, that an adequate underground water supply is readily available for service to individual lots. Evidence shall be submitted that the systems are designed in a manner that each lot may be in the future served by the village water supply system. The location of the individual wells shall be established in accordance with the requirements of the county and the County Health Department. If, after private water supply systems shall be utilized in any subdivisions public water system is installed so that the same is available to the subdivision and the land therein, it shall thereafter be unlawful to utilize private water supply systems, and all properties utilizing private systems shall discontinue their use and make connection to the public water supply system.
(D) Extension of sanitary sewers and water supply installations. The sanitary sewers (required to be installed pursuant to division (B) above) and the water supply (required to be installed pursuant to division (C) above) shall be extended and constructed in, upon, through and along the entire subject property frontage to the next adjoining common property line in order to assure access and extension of the sanitary sewers and water supply, at any future date, by neighboring property owners and the plans, specifications and designs required pursuant to the village code shall indicate the extension required, plus required valves, manholes and/or hydrants prior to the issuance of any building permit.
(Prior Code, § 9C-3D-3) (Ord. 853, passed 5-21-1981)