(A) Plans and specifications.
(1) Drawings for storm drainage improvements shall be prepared on 24-inch by 36-inch sheets, to fit within the municipality’s filing system facilities.
(2) Layout drawings and profiles for storm drainage improvements may be incorporated with the street improvement drawings, but in all cases they shall include but not be limited to, the following information:
(a) Name of subdivision or development;
(b) Name, address, and phone number of subdivider/developer and state registered professional engineer that prepared the design documents;
(c) Date of submittal, with revision block to identify submittal sequence of dates and purpose of submittal;
(d) North arrow (it is preferable that north be up or to the right);
(e) Scale (it is preferable that the scale of plan layout drawings be one inch equals 50 feet, or enlarged scale to more clearly show the layout of the project; it is preferable that the scale of profile drawings be one inch equals 50 feet horizontal and one inch equals five feet vertical, or enlarged scale to more clearly show the layout of the project; other drawings shall use a scale appropriate to clearly indicate the details being shown);
(f) Layout dimensions indicating horizontal and vertical elevation location of all drainage improvements, including indication of spatial relationship to other improvements. Indicate slopes of sewers, culverts, and drainageways, and rim and invert elevations of all manholes, catch basins, inlets, and associated structures;
(g) Location of other utilities and structures that will affect design and construction of storm drainage facilities. Indicate horizontal and vertical clearances where utility lines cross each other and storm sewers; and
(h) Signature and seal of state registered professional engineer that prepared the documents, with date.
(3) (a) Specifications (or special provisions) shall contain sufficient information to demonstrate compliance with requirements of the municipality’s standards and other information as required to identify the specifications that apply to the required improvement.
(b) Specification documents shall be on eight and one-half by 11-inch pages, bound into individual copies.
(1978 Code, § 16.32.860)
(B) Permits.
(1) The engineer engaged by the sub divider/developer to prepare plans and specifications shall prepare all necessary permit application documents applicable the project.
(2) If permits are required to connect to storm drainage facilities under jurisdiction of other agencies (including, but not limited to, state, county, township, drainage district, or other municipality), they shall be obtained by the subdivider/developer or its engineer.
(3) If permits are required to comply with environmental and other regulations through the State Department of Transportation, Corps of Engineers, or Environmental Protection Agency, they shall be obtained by the subdivider/developer or its engineer. Give special attention to requirements for projects adjacent to flood plains, wetlands, and any other areas governed by regulations.
(4) The subdivider/developer shall pay all applicable fees for permits.
(1978 Code, § 16.32.870)
(C) Reference specifications and documents.
(1) Generally. Except where noted otherwise in this subchapter, the following reference specifications, standards, and documents shall apply. The edition current at the time of preliminary plat filing govern.
(2) Reference documents.
(a) Standard Specifications for Road and Bridge Construction, and addenda thereto, State Department of Transportation (referred to as standard R&B specifications);
(b) Highway Standards, State Department of Transportation (referred to in this subchapter as R&B standards);
(c) Design Manual, State Department of Transportation (referred to in this subchapter as R&B Design Manual);
(d) Culvert Manual, State Department of Transportation (referred to in this subchapter as R&B Culvert Manual);
(e) Drainage Manual, State Department of Transportation (referred to in this subchapter as R&B Drainage Manual); and
(f) Frequency Distributions of Heavy Rainstorms in Illinois, Circular 172, Huff, Floyd A. and Angel, James R., State Department of Energy and Natural Resources, State Water Survey (referred to in this subchapter as Circular 172).
(1978 Code, § 16.32.880)
(D) Minimum design requirements; general.
(1) Minimum design requirements set forth in this section shall not be construed as relieving the subdivider/developer of any legal responsibility for downstream or upstream stormwater damages inflicted by runoff or backup of stormwater from the subdivision or development.
(2) All storm sewers, culverts, and conveyance facilities shall be sized on the basis of either the Rational Method, the SCS Method, or both. (1978 Code, § 16.32.890)
(E) Minimum design requirements; design report.
(1) The subdivider/developer’s engineer shall prepare and submit a drainage design report to the municipality in conjunction with submittal of the development plans for required drainage improvements.
(2) The design report shall include, but not be limited to, the following information:
(a) Name of subdivision or development;
(b) Name, address, and phone number of subdivider/developer and state registered professional engineer that prepared the report;
(c) Date of submittal, with revision block to identify submittal sequence of dates and purpose of submittal;
(d) Layout of the subdivision or development and contiguous areas in the affected drainage basin, showing tributary areas (expressed in acres or square feet) of individual drainage basins, contours, and elevations in sufficient detail to identify terrain slopes, design flows expressed in CFS, pipe sizes with slopes, and carrying capacity expressed in CFS;
(e) Supporting engineering calculations to indicate methodology employed in computing storm water flows and conveyance system capacities, including inlet capacities;
(f) List of technical references used for calculations and design of storm drainage facilities, including detention and outlet facilities for stormwater management purposes; and
(g) Signature and seal of state registered professional engineer that prepared the report, with date.
(3) Storm sewers shall be provided on both sides of the right-of-way in order to accommodate the sump pump discharge of subsurface groundwater. This groundwater is not acceptable on city curbs. Alternative methods could be acceptable.
(1978 Code, § 16.32.900)
(F) Minimum design requirements; rainfall intensity. Rainfall intensity shall be based on the Frequency Relations for Madison County, Adjusted for St. Louis Urban Effect, contained in Circular 172.
(1978 Code, § 16.32.910)
(G) Minimum design requirements; time of concentration. The time of concentration shall be identified at critical locations.
(1978 Code, § 16.32.920)
(H) Minimum design requirements; design storm recurrence interval.
(1) New stormwater conveyance facilities shall be designed and constructed with sufficient open channel capacity to transport stormwater runoff (without surcharging) discharged during a ten-year storm recurrence interval in residential areas and during a 25-year storm in commercial and industrial areas, as a minimum;
(2) Give due consideration to the 100-year storm recurrence interval where necessary to assure that damage will not occur in the subdivision or development and in the upstream and downstream areas adjacent to the subdivision or development; and
(3) Do not obstruct flow from upstream areas, and do not increase rate of runoff onto downstream areas.
(1978 Code, § 16.32.930)
(I) Minimum design requirements; stormwater detention facilities.
(1) The rate of stormwater runoff leaving the subdivision or development shall not substantially exceed the flow rate that would have occurred under natural, undeveloped conditions, if it appears that existing or potential downstream developments would be damaged by a greater/faster flow.
(2) (a) Where required to limit the rate of flow, the subdivider/developer shall provide stormwater detention facilities to meet the requirements set forth in this subchapter.
(b) The design of the stormwater detention and outlet facilities shall be in accord with the R&B Drainage Manual. The design report required by these standards shall address stormwater management to properly control runoff of stormwater.
(1978 Code, § 16.32.940)
(J) Materials; precast concrete items.
(1) All manholes, catch basins, and inlets shall be of precast concrete construction, in accord with standard R&B specifications and R&B standards.
(2) Precast concrete supplier shall be approved by IDOT.
(1978 Code, § 16.32.950)
(K) Materials; pipe.
(1) Pipe for storm sewers and culverts shall be reinforced concrete in accord with standard R&B specifications.
(2) Minimum size of storm sewer or culvert shall be not less than 12 inches.
(3) Use of arch or elliptical pipe is permissible if required to provide clearance and necessary depth of cover over top of pipe.
(4) Where storm sewers and culverts discharge to open drainageway, provide precast concrete end sections in accord with standard specifications for R&B and R&B standards.
(1978 Code, § 16.32.960)
(L) Materials; frames and grates.
(1) Ductile or cast iron frames and grates for manholes, catch basins, and inlets shall comply with the standard R&B specifications and R&B standards, and shall meet the acceptance of the municipality’s Superintendent of Streets;
(2) Open grates shall be of a pattern and design recommended for bicycle traffic;
(3) Provide sufficient grate open area, with single or multiple inlet points, to allow entry of design storm flow into storm sewer without creating excessive ponding conditions; and
(4) Set frames and grates on full mastic bed.
(1978 Code, § 16.32.970)
(M) Installation and construction; general. Installation and construction shall be in accord with standard R&B specifications.
(1978 Code, § 16.32.980)
(N) Installation and construction; record drawings.
(1) Record drawings shall be furnished to the municipality within ten days after new stormwater facilities are accepted and placed into service, and prior to issuance of any building permits in the subdivision or development.
(2) Record drawings shall be reproducible, good quality polyester film, or Autocad diskette compatible with the municipality’s computer system. Record drawings shall include sizes, lengths, and horizontal and vertical locations (elevations) of all facilities to accurately reflect as-constructed conditions.
(1978 Code, § 16.32.990)
(Ord. 96-12, passed - -1996)