A. An adequate system of stormwater drainage shall be constructed and installed, consisting of pipes, stormwater detention facilities, tiles, swales, manholes, inlets and other necessary facilities that will adequately drain the subdivision and protect roadway pavements and buildings from flooding.
B. Computations for the storm sewer system for on site and off site drainage shall be presented with the preliminary plat for approval.
C. The drainage system shall include underground piping for sump pump connections. Said piping (4 inches minimum) shall extend from either the front or rear of each building lot to the storm sewer system and include manholes and/or cleanouts for maintenance purposes. The sump pump drainage system shall be subject to the approval of the village engineer.
D. All storm sewer runoff from adjacent areas shall be received and conveyed through the subdivision.
E. Whenever any stream or important surface drainage course is located in any area which is being subdivided, the subdivider shall reserve an adequate drainage right of way as determined by the village and the Illinois department of transportation, division of water resources along each side of the stream for the purpose of widening, deepening, sloping, improving, or protecting the stream.
F. The storm sewer system shall be designed in accordance with the rational method (with runoff coefficient "C" values to be 0.25 for pervious and 0.95 for impervious areas) using a 10-year storm frequency or other methods approved by the village engineer. Intensities shall be determined from the Illinois state water survey bulletin 70 as summarized below. The time of concentration shall be computed using worksheet three as published in the USDNNRCS TR-55. Culvert design and capabilities shall be determined according to the Illinois department of highways standard design methods using a 25-year storm frequency.
ILLINOIS STATE WATER SURVEY BULLETIN 70
RAINFALL DEPTHS FOR NORTHEAST SECTIONAL
Duration | Frequency | ||||||
1-Year | 2-Year | 5-Year | 10-Year | 25-Year | 50-Year | 100-Year | |
Duration | Frequency | ||||||
1-Year | 2-Year | 5-Year | 10-Year | 25-Year | 50-Year | 100-Year | |
5 minute | 0.30 | 0.36 | 0.46 | 0.54 | 0.66 | 0.78 | 0.91 |
10 minute | 0.55 | 0.67 | 0.84 | 0.98 | 1.21 | 1.42 | 1.67 |
15 minute | 0.68 | 0.82 | 1.03 | 1.21 | 1.49 | 1.75 | 2.05 |
30 minute | 0.93 | 1.12 | 1.41 | 1.65 | 2.04 | 2.39 | 2.80 |
1 hour | 1.18 | 1.43 | 1.79 | 2.10 | 2.59 | 3.04 | 3.56 |
2 hour | 1.48 | 1.79 | 2.24 | 2.64 | 3.25 | 3.82 | 4.47 |
3 hour | 1.60 | 1.94 | 2.43 | 2.86 | 3.53 | 4.14 | 4.85 |
6 hour | 1.88 | 2.28 | 2.85 | 3.35 | 4.13 | 4.85 | 5.68 |
12 hour | 2.18 | 2.64 | 3.31 | 3.89 | 4.79 | 5.62 | 6.59 |
18 hour | 2.30 | 2.79 | 3.50 | 4.11 | 5.06 | 5.95 | 6.97 |
24 hour | 2.51 | 3.04 | 3.80 | 4.47 | 5.51 | 6.46 | 7.58 |
48 hour | 2.70 | 3.30 | 4.09 | 4.81 | 5.88 | 6.84 | 8.16 |
72 hour | 2.93 | 3.55 | 4.44 | 5.18 | 6.32 | 7.41 | 8.78 |
120 hour | 3.25 | 3.93 | 4.91 | 5.70 | 6.93 | 8.04 | 9.96 |
240 hour | 4.12 | 4.95 | 6.04 | 6.89 | 8.18 | 9.38 | 11.14 |
G. All manholes, catch basins, inlets, pipe, frames and grates shall be of the type approved by the village engineer. Storm sewer shall be reinforced concrete pipe (RCP) conforming to ASTM C-76, wall thickness B. All storm sewers shall be placed within public rights of way or public utility easements. Storm sewers in side yards shall be avoided if at all possible and shall be subject to approval by the village engineer. Lids shall have the words "STORM" and "VILLAGE OF WINFIELD" cast on the top. Two feet (2') of cover above the top of pipe shall be provided for all storm sewers. Grates are required on all flared end sections.
H. Intercepting stormwater structures, including catch basins and inlets, shall be provided at intervals not in excess of two hundred seventy five (275) maximum feet, as measured along the flow line. The stormwater drainage system shall be separate and independent of the sanitary sewer system. Storm sewers and appurtenant structures shall be constructed in accordance with the "Standard Specifications For Road And Bridge Construction", published by the Illinois department of transportation. All storm sewers to be televised prior to acceptance.
I. No water from footing tiles or basement sumps shall be pumped or discharged onto the ground surface. Such water discharge pipes shall be discharged directly into storm sewer system.
1. Construction of discharge piping from footing tiles and sump pumps, of storm sewers, and of appurtenant structures shall be in accordance with ICC, edition in force by the village.
2. Pipe material for discharge pipe from house and secondary drainage system shall be PVC with a minimum SDR of 35, ASTM 3034, four inch (4") minimum for sump pump pick up, and ten inch (10") diameter secondary storm sewer if only sump discharge is collected.
3. A piping shall be laid on a uniform grade with minimum grade of one-fourth inch (1/4") per foot and a minimum depth of cover of three feet (3').
4. A minimum four inch (4") diameter pipe shall service the house or building. The four inch (4") pipe may be installed along a common lot line and service two (2) houses or buildings. Said four inch (4") line shall be furnished with a cleanout at its terminus. Note that a six inch (6") diameter line shall be required for two (2) or more house connections.
5. A minimum four inch (4") diameter pipe shall connect the junction box to the storm sewer system. If two (2) sump pump connections are joined, a six inch (6") diameter PVC SDR 35 line shall extend from that point. No more than two (2) lines may be joined. A minimum ten inch (10") diameter pipe shall be used as secondary drainage extension. In no case shall a small diameter sump line extend to discharge at a swale or basin. All sump discharge connections shall be to public RCP storm sewer line only.
6. Dead ends of storm systems shall be provided with a minimum twenty four inch (24") diameter precast concrete inlet for cleanout purposes. Design approved by the village engineer.
7. Any connection between house sump pump discharge pipe and the secondary drainage system and between the secondary drainage system and storm sewer system shall be made with factory made fittings, wyes and tees. No cut in of piping will be allowed. (Ord. 2015-02-05, 2-5-2015)