(a) Purpose.
(1) The Subdivision, Condominium or Certified Survey Map Developer (as applicable) shall construct stormwater drainage facilities, adequate to serve the subdivision which may include curbs and gutters, catch basins and inlets, storm sewers, road ditches, open channels, water retention structures and settling basins. All such facilities shall be of adequate size and grade to hydraulically accommodate the maximum potential volumes of flow and shall be so designed as to prevent and control soil erosion and sedimentation and to present no hazards to life or property. Applicable standards to be complied with are as prescribed in this Chapter and in Title 15, Chapter 3 Post- Construction Stormwater Management, whichever is most restrictive.
(2) Shoreland drainage facilities shall, if required, include water retention structures and settling basins so as to prevent erosion and sedimentation where such facilities discharge into streams or lakes. The design criteria, the size, type, grades and installation of all storm water drains and sewers and other cross-section, invert and erosion control paving check dams, flumes or other energy dissipating structures and seeding and/or sodding of open channels and unpaved road ditches proposed to be constructed shall be in accordance with the plans and standard specifications approved by the Village Engineer.
(3) The Subdivision, Condominium or Certified Survey Map Developer (as applicable) shall assume the cost of installing all storm sewers of thirty-six (36) inches or smaller within the proposed subdivision, except for the added cost of installing storm sewers greater than thirty-six (36) inches which are necessary to serve tributary drainage areas lying outside of the proposed subdivision. In addition, the Subdivision, Condominium or Certified Survey Map Developer (as applicable) shall pay to the Village, a storm sewer trunk line connection fee based on the added cost of installing larger sewers in the total tributary drainage area which shall be prorated in proportion to the ratio which the total area of the proposed plat is to the total drainage area to be served by such larger sewers.
(4) The following provisions in this Section are established to preserve and provide properly located public sites and facilities for drainage and stormwater management as the community develops, and to insure that the costs of providing and developing such public sites are equitably apportioned on the basis of serving the need for the management of increased stormwater quantities resulting from land development.
(b) Drainage System Required. As required by Section 14-1-56, a drainage system shall be designed and constructed by the Subdivider/Developer to provide for the proper drainage of the surface water of the land division and the drainage area of which it is a part. Post- development peak runoff rates shall be limited to pre-development levels, up to and including twenty-five (25) year return period storms. A Final Plat or Condominium Plan shall not be approved until the Subdivision, Condominium or Certified Survey Map Developer (as applicable) shall submit plans, profiles and specifications as specified in this Section, which have been prepared by a registered professional engineer and approved or modified by the Village Board, upon the recommendations of the Plan Commission and/or Village Engineer.
(c) Drainage System Plans.
(1) The Subdivision, Condominium or Certified Survey Map Developer (as applicable) shall submit to the Village at the time of filing a Final Plat a drainage plan or engineering report on the ability of existing watercourse channels, storm sewers, culverts and other improvements pertaining to drainage or flood control within the subdivision to handle the additional runoff which would be generated by the develop- ment of the land within the project. Additional information shall be submitted to adequately indicate that provision has been made for disposal of surface water without any damage to the developed or undeveloped land downstream or below the proposed Subdivision. The report shall also include:
a. Estimates of the quantity of stormwater entering the subdivision naturally from areas outside the subdivision.
b. Quantities of flow at each inlet or culvert.
c. Location, sizes and grades of required culverts, storm drainage sewers and other required appurtenances.
(2) A grading plan for the streets, blocks and lots shall be submitted by the Subdivision, Condominium or Certified Survey Map Developer (as applicable) for the area within the land development.
(3) The design criteria for storm drainage/detention systems shall be based upon infor- mation provided by the Village Engineer, and a plan for permanent maintenance.
(4) Material and construction specifications for all drainage projects (i.e., pipe, culverts, seed, sod, etc.) shall be in compliance with specifications provided by the Village Engineer.
(d) Drainage Plan Information. In addition to the requirements of any other applicable storm water runoff ordinance, the final drainage plan shall contain the following information:
(1) Scale, north point and date of preparation.
(2) The number of acres draining into the land development and the number of acres in the development.
(3) Lot numbers corresponding to the plat.
(4) Direction of flow indicated by arrows on all lot lines, grades along lot lines, elevations of break points along lot lines, and the distance from the nearest lot comer in the break point.
(5) Easements which shall be on the final plat.
(6) Contour information shall be provided in the drainage plan at vertical intervals of not more than two (2) feet, where the stope is less than ten percent (10%), and not more than five (5) feet, where the slope is greater than ten percent (10%). All elevations shall be based on the verified datum plan of the USGS.
(7) Reference to an established USGS benchmark.
(8) Acres to be filled showing the depth of fill, existing elevation and proposed elevation.
(9) Typical proposed street and ditch cross sections.
(10) All culvert sizes, where applicable.
(11) Where a development is to be serviced by a storm sewer or sump pump shallow collector sewer, the size of pipe, proposed elevations, discharge points, inlets and lateral size shall be indicated.
(12) Area where water is to be discharged from the land development and the proposed amount of discharge. Where required by state, federal, county or local regulations, detention facilities shall be specified with a designation and description of impact on smface water discharge.
(13) The final grade elevations and grade of the drainage ways in percent slope shall be provided along the front, rear and side yard lot lines. Each lot shall have an established grade identified at each comer of the lot or parcel and at any change in grade or slope along the front, rear and side yard lot lines and for the ground grade at the foundation.
(14) The land development shall note on the Final Plat that the Village of Edgar requires the maintenance of lot drainage plans on a permanent basis. Said recording shall have the effect of deed restrictions requiring that permanent lawns be established in conformance with the lot drainage plan elevations within one (1) year after initial occupancy of any house. Restrictions shall further provide that failure to maintain grades in accordance with storm water or drainage plans shall entitle the Village or its representatives thereof to direct compliance or upon failure of compliance to make said lands come into compliance. The costs and expenses shall be entered on the tax roll as a special charge against the property and collected with other taxes levied therein.
(15) The deed restrictions noted on the final plat shall include notice that building permits and occupancy permits may be withheld for noncompliance with the plat or Village ordinance(s) as follows:
a. In the event that the surface drainage facilities required by the plat which are applicable to the lot for which a building permit has been applied for have not been complied with, the Building Inspector may withhold building permits required by the Village of Edgar Building Code (Title 15).
b. In the event that after construction there is a failure to establish surface grades in accordance with the subdivision surface water plan, the Building Inspector may withhold the occupancy permit required by the Building Code.
(16) Any other information which shall be required by the Village of Edgar.
(e) Final Drainage Plan Transparency. A reproducible transparency of the final drainage plan shall be supplied to the Village prior to the approval of the Final Plat.
(f) Storm Inlet Restrictive Covenants.
(1) Where the final drainage plan requires a storm inlet to adequately drain the rear portion of lots within blocks of the land development, the Subdivision, Condominium or Certified Survey Map Developer (as applicable) shall incorporate restrictive covenants in the deeds for the aforementioned lots that the respective lot owners shall be responsible for maintaining a clear grate on the aforementioned storm drainage inlets. The Subdivision, Condominium or Certified Survey Map Developer (as applicable) shall also incorporate restrictive covenants in the deeds of any parcel abutting any drainage way/easement specific in the plat requiring the maintenance of grades and notice that the owner shall be subject to assessments necessary to remedy encroachments and obstructions by said lot owner.
(2) The restrictive covenants in the deeds and as noted on the face of the plat shall notify the owner of any parcel within the land development that the lot or parcel shall also be subject to special assessments for any and all work necessary to maintain the final drainage plan in accordance with the specifications of the plat.
(g) Grading. The Subdivision, Condominium or Certified Survey Map Developer (as applicable) shall grade each subdivision in order to establish street, block and lot grades in proper relation to each other and to topography as follows:
(1) The Subdivider/Developer shall grade the full width of the right-of-way of all proposed streets in accordance with the approved plans.
(2) Block grading shall be completed by one (1) or more of the following methods:
a. A ridge may be constructed along the rear lot lines which provides for drainage onto the streets.
b. Parts of all lots may be graded to provide for drainage to the street or to a ditch along the rear lot line.
c. Draining across rear or side lot lines may be permitted provided that drainage onto adjoining properties is skillfully controlled.
(h) Drainage System Requirements. The Subdivision, Condominium or Certified Survey Map Developer (as applicable) shall install all the storm drainage facilities indicated on the plans required in Subsection (a) of this Section necessary to serve, and resulting from, the phase of the land division under development:
(1) Street Drainage.
All streets shall be provided with an adequate storm drainage system. The street storm system shall serve as the minor drainage system and shall be designed to carry street, adjacent land and building stormwater drainage. Storm water shall not be permitted to be run into the sanitary sewer system within the proposed subdivision.
(2) Off-Street Drainage.
The design of the off-street major drainage system shall include the entire watershed affecting the land division and shall be extended to a watercourse or ditch adequate to receive the storm drainage. When the drainage system is outside of the street right-of-way, the Subdivision, Condominium or Certified Survey Map Developer (as applicable) shall make provisions for dedicating an easement to the Village to provide for the future maintenance of said system, per Subsection G).
(i) Protection of Drainage Systems.
The Subdivision, Condominium or Certified Survey Map Developer (as applicable) subdivider shall adequately protect all ditches to the satisfaction of the Village Engineer. Ditches and open channels shall be seeded, sodded or paved depending upon grades and soil types. [Generally ditches or channels with grades up to one percent (I%) shall be seeded; those with grades up to four percent (4%) shall be sodded, and those with grades over four percent (4%) shall be paved.]
(j) Drainage Easements.
Where a Subdivision, Certified Survey Map or Condominium project is traversed by a watercourse, drainageway, channel or stream:
(1) There shall be provided a stormwater easement or drainage right-of-way conforming substantially to the lines of such watercourse and such further width or construction, or both, as will be adequate for the purpose and as may be necessary to comply with this Section; or
(2) The watercourse, drainageway, channel or stream may be relocated in such a manner that the maintenance of adequate drainage will be assured and the same provided with a stormwater easement or drainage right-of-way conforming to the lines of the relocated watercourse, and such further width or construction, or both, as will be adequate for the purpose and may be necessary to comply with this Section; or
(3) Wherever possible, drainage shall be maintained in an easement by an open channel with landscaped banks and adequate width for maximum potential volume flow. In all cases, such easements shall be of a minimum width established at the high water mark or, in the absence of such specification, not less than thirty (30) feet.
(k) Dedication of Drainageways.
(1) Whenever a parcel is to be subdivided or consolidated and embraces any part of a drainageway identified on a Village Comprehensive Storm Water Management Plan, Comprehension Plan and/or Official Map or any portion thereof, such part of said existing or proposed public drainageway shall be platted and dedicated by the Subdivision, Condominium or Certified Survey Map Developer (as applicable) as an easement or right-of-way in the location and at the size indicated along with all other streets and public ways. Maintenance arrangements shall be as prescribed in Subsection (n) below.
(2) Whenever any parcel is to be subdivided or consolidated and is part of a drainage district established under the authority of Chapter 88, Wis. Stats., the Subdivision, Condominium or Certified Survey Map Developer (as applicable) shall petition the Circuit Court to transfer the jurisdiction of that portion of the drainage district being subdivided or consolidated to the Village in accordance with Ch. 88.83, Wis. Stats.
(I) Dedication/Preservation of Stormwater Management Facilities. The Subdivision, Condominium or Certified Survey Map Developer (as applicable) shall dedicate sufficient land area for the storage of stormwater to meet the needs to be created by the proposed land development and in accordance with the standards for on-site detention and as determined by the Village Engineer. Whenever a proposed stormwater management facility (e.g., detention or retention basin) shown on the Comprehensive Stormwater Management Plan, master plan and/or official map is located, in whole or in part, within the proposed land division, ground areas for providing the required storage capacity in such proposed public facility shall be dedicated to the public or property owners association, as determined by the Village, to the requirements of the master plan and/or official map. Storage areas necessary to serve areas outside the land division shall be held in reserve for a period of five (5) years from the date of final plat approval for future dedication to the Village or other appropriate agency.
(m) Storm Drainage Facilities.
(1) The Subdivision, Condominium or Certified Survey Map Developer (as applicable), at his/her cost, shall install all drainage facilities identified in the Erosion Control Plan or determined by the Village Engineer as being necessary for the management of all lands and roadways within the development. In addition, drainage capacity through the development from other areas shall be provided in accordance with a Comprehensive Surface Water Management Study, if applicable. All required storm drainage facilities shall be constructed and operational prior to acceptance of any dedications and/or public improvements served by the storm drainage facilities.
(2) The Subdivision, Condominium or Certified Survey Map Developer (as applicable) shall submit to the Village Engineer for his/her review and approval a report on the ability of existing watercourse channels, storm sewers, culverts and other improve- ments pertaining to drainage or flood control within the land division to handle the additional runoff which would be generated by the development of the land within the land division. Additional information shall be submitted to adequately indicate that provision has been made for disposal of surface water without any damage to the developed or undeveloped land downstream or below the proposed land division. The report shall also include:
a. Estimates of the quantity of storm water entering the land division naturally from areas outside the land division.
b. Quantities of flow at each inlet or culvert.
c. Location, sizes and grades of required culverts, storm drainage sewers and other required appurtenances.
(3) A grading plan for the streets, blocks and lots shall be submitted by the subdivider for the area within the land division.
(4) The design criteria for storm drainage systems shall be reviewed by the Village Engineer and approved or modified.
(5) Material and construction specifications for all drainage projects (i.e., pipe, culverts, seed, code, etc.) shall be in compliance with standards and specifications provided by Village ordinance and/or the Village Engineer.
(n) Maintenance Agreement.
(1) A maintenance agreement shall be required between the Village and the Subdivision, Condominium or Certified Survey Map Developer (as applicable). The agreement shall be recorded as a property deed restriction by the subdivider with the County Register of Deeds in a form which shall be binding upon all subsequent owners of land covered by the agreement. Such agreement shall assign on-going responsibility for maintenance and repair of the stormwater management system, including detention/retention facilities and drainageways, to a homeowners, property owners or condominium association per Sec. 14-1-23. Prior to Final Plat approval, the Subdivision, Condominium or Certified Survey Map Developer (as applicable) subdivider shall submit to the Village for its approval an on-going maintenance and mowing plan for such facilities, which shall be incorporated by reference into all approvals and development agreements. In the alternative, if unique circumstances or a special benefit to the public can be demonstrated, such ownership and maintenance responsibility may be assumed by the Village of Edgar.
(2) If the Village at any time finds that the stormwater management measures constructed in accordance with the system plan are not being properly maintained, or if altered in any way from the location, configuration and capacity of the measures specified in the approved plan, the Village shall have the right to undertake the needed maintenance or repair. This right shall include the right to enter onto private property as necessary to carry out the needed maintenance or repair. The cost of such maintenance or repair shall be levied as a special assessment or special charge against the properties concerned. The special charge or assessment shall be collectible in the same manner as all other special assessments/charges levied by the Village of Edgar.
(o) Minor Drainage System. The Subdivision, Condominium or Certified Survey Map Developer (as applicable) shall install all minor drainage system components necessary to reduce inconvenience and damages from frequent storms. Minor drainage components shall include all inlets, piping, gutters, channels, ditching, pumping and other facilities designed to accommodate the post-development runoff resulting from a ten (10) year, twenty-four (24) hour rainfall event as determined in the most current edition of the Soils Conservation Service Technical Release 55 (TR 55) or the "Rational Method". Temporary accumulations of storm runoff from ponding or flowing water, in or near minor system components, shall be petmitted providing such accumulations do not allow the water to flow across the crown of the street from one side to the other. For arterial streets and streets located in commercial districts, ponding within normal traffic lanes [ten (10) feet on each side of the centerline of the street] is prohibited. In drainageways and drainageway easements, accumulations of water shall not inundate beyond the limits of the drainageway or drainageway easement. Cross-street drainage channels (valley gutters) shall not be permitted except on cul-de-sac or permanent dead-end streets serving less than ten (10) dwelling units and where the minimum grade in the valley gutter and street gutter between the valley gutter and the next downstream drainage inlet is not less than one percent (1.00%).
(p) Major Drainage System. The Subdivision, Condominium or Certified Survey Map Developer (as applicable) shall install all major drainage system components necessary to reduce inconvenience and damages from infrequent storms. Major system components shall include large channels and drainageways, streets, easements and other paths and shall be capable of accommodating post-development runoff in excess of that accommodated by minor system components resulting from twenty-four (24) hour rainfall events for storms with return frequencies greater than two (2) years up to and including the one hundred (100) year return event (as identified in TR 55). Runoff resulting from a one hundred (100) year, twenty-four (24) hour rainfall event shall be contained within the street right-of-way or designated storm drainage easement or detention facility.
(q) Drainage Piping Systems.
(1) Unless otherwise approved by the Village Engineer, all drainage non-driveway piping of twelve (12) inches diameter and greater in street rights-of-way shall be constructed of Class Three reinforced concrete or PVC pipe. Piping materials outside of rights-of- way shall be subject to approval of the Village Engineer. All storm sewer outlets shall be equipped with steel bar or iron pipe debris gates.
(2) Agricultural drain tiles which are disturbed during construction shall be restored, reconnected or connected to public storm drainage facilities.
(r) Open Channel Systems.
(1) Unless recommended otherwise by the Village Engineer, unpaved road ditches and street gutters shall be permitted only within the Village's extraterritorial plat approved jurisdictional area and shall be shaped and seeded and/or sodded as grassed waterways. Where the velocity of flow is in excess of four (4) feet per second on soils having a severe or very severe erosion hazard and in excess of six (6) feet per second on soils having moderate, slight, or very slight erosion hazard, the Subdivider/Developer shall install check dams, flumes, or other energy dissipating devices.
(2) Where open channels are utilized in either the minor or major drainage system, they shall be designed so as to minimize maintenance requirements and maximize safety. Drainage easements (in lieu of dedications) shall be utilized to accommodate open channels provided adequate access by the Village for maintenance of drainage capacity. Side slopes shall not exceed a four-to-one (4:1) slope. Drainageways where subject to high ground water, continuous flows, or other conditions as determined by the Village Engineer that would hamper maintenance operations due to consistently wet conditions, shall have a paved concrete invert of not less than eight (8) feet wide and side slopes to a point one (I) foot above the channel invert.
(3) In areas where invert paving is not required, the drainageway bottom shall be grass. If the drainageway has a bare soil bottom or the natural grasses in the drainageway are disturbed due to development operations, the drainageway bottom shall be sodded and securely staked to one (1) foot above the elevation of inundation resulting from a predevelopment five (5) year, twenty-four (24) hour storm event. Other disturbed areas shall be seeded and prepared in accordance with the Village's Erosion Control requirements. Velocities for grass-lined channels shall not exceed those presented in the Village's Surface Water Management Study, if one is adopted.
(s) Standards for On-Site Detention Storage. When the Subdivision, Condominium or Certified Survey Map Developer (as applicable) employs on-site detention to control erosion and sedimentation, reduce the post-development peak runoff rate or temporarily store storm water runoff due to inadequate downstream drainage facilities. The detention (storage) facilities shall be subject to regulation in accordance with the following standards:
(1) Temporary on-site detention for erosion and sedimentation control shall be designed in conformance with the "Wisconsin Construction Site Best Management Practices Handbook".
(2) Where on-site detention is permanently employed to reduce the post-development peak runoff, the detention facility shall safety contain the post-development runoff from a twenty-five (25) year storm event of twenty-four (24) hour duration within the limits of the facility.
(3) Post-development peak runoff rates shall be limited to pre-development levels, up to and including twenty-five (25) year return period storms. Curve numbers of 30, 58, 71 and 78 for Hydrologic Soil Groups A, B, C and D respectively shall be used when computing pre-development runoff rates.
(4) All detention facilities shall safety contain or pass the runoff from any storm of any duration which exceeds the maximum storm required to be contained up to the one hundred (100) year storm event of twenty-four (24) hour duration.
(5) All permanent detention facilities shall safety contain the runoff from the one hundred (100) year storm event of twenty-four (24) hour duration on both public and, if necessary, private properties without inundating any building at the ground elevation, the travel lanes of any arterial street, the center ten (10) feet of any collector street or the top of the curb on any local street.
(6) Determination of on-site detention volumes shall be computed by procedures established by the United States Soil Conservation Service in the most current edition of its technical publication entitled "Urban Hydrology for Small Watersheds, TR-55 or TR-20," and as accepted and approved by the Village Engineer.
(7) The storage of storm water runoff shall not encroach on any public park (except parks designed with detention facilities) or any private lands outside the land division unless an easement providing for such storage has been approved and recorded for said lands.
(8) All detention facilities shall be designed with the safety of the general public and any considerations for ease of maintenance as top proprieties.
(9) Any wet detention facilities shall include riprap to not less than two (2) feet above the normal pool elevation for protection from wave action, or other slope stabilization methods approved by the Village Engineer, for protection from wave action.
(10) The sides of all detention facilities shall have a maximum slope ratio of four to one (4:1) (horizontal to vertical), with flatter slopes being required where determined practical by the Village Engineer.
(11) The Village Board, upon recommendation by the Village Engineer, may require the installation of fencing or other such security measures in detention facilities with excessively long down times or permanent water features, or other features requiring additional security for safety reasons.