(A) Pavement.
(1) No vertical curve shall be established unless the algebraic differential of grades is greater than 1.2%.
(2) On any vertical curve, the grade shall be at least 0.4% between adjacent points.
(3) No top of curb or gutter grade shall be less than 0.4%.
(4) The maximum pavement grade shall not exceed 4% (3% within 100 feet of intersections) except in cases of extreme necessity with prior approval of the village’s engineering representative.
(5) Maximum grade differentials should not exceed 2% and must not exceed 3% on pavements without prior approval of the village’s engineering representative.
(6) Top of pavement grades shall be established on intersection details at the following locations:
(a) At all ends of radii in gutter and on pavement centerline;
(b) At gutter in center of radii;
(c) At radii P.I.s;
(d) Intersection of pavement centerline with lines connecting radius P.I.s;
(e) Intersection of pavement centerlines; and
(f) Any other point necessary to clarify drainage and reduce bump.
(7) Minimum curb radius shall be at least 25 feet.
(8) Inlets and catch basins shall be located at, or beyond end of radius. (If radius is 30 feet or greater, inlets and catch basins may be located in radius with prior approval of the village’s engineering representative).
(9) Through gutters will not be allowed.
(B) Design of storm sewer systems. The design of storm sewer systems will be based upon the “Rational Method” using the equation Q = CIA, and the “Manning Formula”.
(1) The rainfall intensity, V, will be taken from the appropriate curve for the county area as published in the current technical paper of the U.S. Weather Bureau, Rainfall Intensity-Duration- Frequency Curves for Selected Stations in the United States, Alaska, Hawaiian Islands and Puerto Rico Government Printing Office.
(2) t = 20 minutes shall be used as the time of consideration to the first pick-up point in the system in residential areas.
(3) The following runoff coefficients shall be used in residential areas.
Average Lot Size | *Runoff Coefficient “C” |
7,200 sq. ft. or less | 0.40 |
7,200 sq. ft. to 9,600 sq. ft. | 0.35 |
9,600 sq. ft. or more | 0.30 |
* Includes right-of-way areas. | |
(4) Storm sewers shall be designed to flow just full for the five-year intensity-duration- frequency curve. Minimum pavement gutter elevations shall be at or above the hydraulic grade line for a ten-year frequency storm. Use the ten-year intensity-duration-frequency curve for determining this hydraulic grade line.
(5) Catch basin type and spacing shall be designed using the two-year intensity-duration- frequency curve. The maximum allowable width of the sheet gutter flow from the face of the curb shall be limited to eight feet.
(6) (a) An overall drainage area layout plan showing the limits of the contributing runoff area, broken down into areas contributing to each drainage pick-up point, shall be submitted with the paving and drainage plans. Drainage design within the development shall be adequate to handle the entire contributing watershed area, and its existing, proposed, and probable future development, and not the area under submission only. Drainage design which makes use of an existing system shall follow practical engineering judgement.
(b) If future plat extensions will utilize the same drainage system, the overall drainage plan shall be submitted with the first plat paving plans.
(7) Complete drainage calculations shall be submitted for pipe size determinations, ten-year hydraulic gradient checks, and catch basin type and spacing designs.
(8) Storm water runoff control criteria. Storm water runoff control addresses both peak and total volume of runoff. The peak rate of runoff from an area after development shall not exceed the peak rate of runoff from the same area before development for all storms up to a 100-year frequency, 24-hour storm. Required detention volume shall be calculated using a 25-year design storm with the maximum allowable peak rate of discharge equal to a five-year storm with a 20 minute time of concentration and a predeveloped runoff coefficient of 0.15.
(9) (a) Storm sewers and culverts shall be designed to conform to the requirements of the state’s Department of Transportation Construction and Materials Specifications, current edition. Pipe under pavement shall be of Type “A” and “B” Conduit with Class “A” or “B” Bedding. Pipe not under pavement shall be Type “C” or “D” Conduit with Class “A” or “B” Bedding. The designer may indicate a particular kind of pipe by inserting the specification item number after the designation of the type of conduit. The use of metal pipe will not be permitted without prior approval of the village’s engineering representative. Depth of cover shall be the determining factor in selecting the proper strength of pipe. Minimum cover for Type “A” or “B” Conduit shall have a minimum cover of nine inches, measured from the top outside crown of the pipe to the finished subgrade.
(b) Polyvinyl chloride conduit acceptable for storm sewer installation shall meet or exceed ASTM D3034 specification SDR 35, (PS 46) with joints meeting ASTM D-3212 specifications.
(10) Granular material to be used for pipe backfilling shall meet the requirements of Item 310.02. This statement shall appear on all plans as a general note or on the standard details.
(11) Granular material to be used for pipe bedding shall be No. 8 or No. 67 stone. This statement shall appear on all plans as a general note or on the standard details.
(12) All catch basins are to be constructed without sumps or traps.
(13) Outlets for footer tile drainage shall be provided for all lots in new subdivisions.
(a) All storm sewers within the public right-of-way shall be designed to include a tee, wye, or cross-over connection, extending ten feet beyond the right-of-way or property line into each lot, to provide a connection for each lot within the subdivision.
(b) In areas where street drainage would normally be provided by gutter flow only, the storm sewer shall be extended beyond its normal upper terminus so as to serve those lots that would not normally front on a storm sewer. Tees, wyes, or cross-overs will be provided for each lot.
(c) The “extended storm sewer” shall be designed for a capacity of flow equal to 1.25 gallons per minute from each house served, but shall have a minimum diameter of six inches and a Minimum grade of 1%.
(d) All cross-overs shall have a minimum grade of 1%.
(e) Locations and elevation of all taps shall be indicated on the subdivision paving plan.
(f) Manholes will be provided at intervals not to exceed 350 feet, at all abrupt changes in the direction of the sewer line and at the upper terminus of any “extended storm sewers”.
(g) All storm sewer services shall be extended ten feet beyond the right-of-way or property line into each lot. For a single lot, the service shall be six-inch minimum diameter.
(h) Details of design, materials, and construction procedures shall be in accordance with the current “Design Criteria”.
(i) In subdivisions where the construction of basements or crawl spaces are prohibited by the developer’s restrictions, the foregoing requirements will not apply. Such restrictions, however, shall be recited on the record plat.
(C) Pavement design requirements.
(1) Soil tests.
(a) Soil tests shall be furnished for every 600 lineal feet of pavement with a minimum of one test per pavement. The village and/or the village’s engineering representative will be given the opportunity to approve the location of soil boring on private work prior to the test being made, and reserves the right to require additional teats if unusual conditions exist.
(b) All borings shall be made to a minimum depth of three feet below the proposed top of curb grade, unless rock is encountered or extreme grade changes are proposed for the subdivision/improvement site.
(c) Tests of each different soil layer encountered below the proposed grade line shall include the following:
1. Moisture determination (actual and optimum);
2. AASHTO Classification and group index (each sample);
a. Atterburg limit;
b. Liquid limit;
c. Plastic limit; and
d. Plasticity index.
3. Mechanical analysis;
4. Laboratory C.B.R. of Modulus of Subgrade Reaction “K” may be made in the following manner. Where more than one soil test is taken on a given project, the Laboratory C.B.R. or Modulus of Subgrade Reaction”K” shall be made on the sample indicating the highest group index, providing that the group indices fall within a range of five. If the group indices do not fall within a range of five, a Laboratory C.B.R. or Modulus of Subgrade Reaction “K” shall be made for the highest indicated group index to each range of five of the soil tests made. If all the group indices have the same value, the Laboratory C.B.R. or Modulus Subgrade Reaction “K” shall be made on the sample having the highest percent of particles passing the No. 200 Sieve;
5. Maximum laboratory dry weight; and
6. Elevation of water table (should be recorded 12 to 24 hours after water is encountered during boring operations).
(d) All soil tests will be performed by a recognized laboratory acceptable to the village.
(2) Pavement design.
(a) The current list of manuals and standards to be used in the design of pavements are as follows:
1. Manual of Location and Design by the state’s Department of Transportation;
2. Construction and Materials Specifications; state’s Department of Transportation - current edition;
3. The Design of Concrete Pavements for City Streets by the Portland Cement Association (1963); and
4. Thickness Design for Concrete Pavements by the Portland Cement Association (1966).
(b) Pavement design shall be based on equivalent daily 18,000 lbs, single axle applications as indicated. Streets which are to serve as major or minor collectors, arteries, or have special traffic conditions shall require actual classification counts or estimates. The following approach is usable for residential neighborhood streets only.
(c) The normal residential street shall have a 20-year design for four axles per lane per day at the legal limit of 18,000 lb. single axle or 32,000 lb. dual axle.
(d) If the maximum dry weight of the soil is less than 100 pounds per cubic foot, a minimum of four-inch subbase course shall be used on either section called for.
(e) Design calculations shall be submitted along with proposed typical and proposed grade line with the soil test holes superimposed on the profile. A complete soil test report shall be submitted with the aforementioned.
(3) Strength of materials. Rigid - The modulus of rupture used shall be considered 600 psi. The absolute minimum allowable design of Portland cement concrete pavement with integral concrete curbs will be seven inches in depth and will include longitudinal joint epoxy coated tie bars.
(Ord. 1235, passed 7-16-2002)