In addition to the open space requirements, the standards and mitigation requirements in this section apply to those resources indicated:
A. Water Bodies: Only shoreline protection and piers or other structures approved as water dependent uses shall be permitted in water bodies provided they meet the requirements of this section.
1. Shoreline Protection: This use shall be permitted subject to the following standards being met:
a. A corps of engineers permit shall be required.
b. In all cases, the shoreline protection technique permitted shall be in the following order of preference. A technique lower on the order of preference shall not be used unless it is demonstrated that a higher order will not work at the location or is not cost effective.
(1) Emergent and shoreline vegetation.
(2) Emergent and shoreline vegetation with submerged or semisubmerged stabilizing rock to permit the establishment of the vegetation.
(3) Spot armoring to protect lower areas.
(4) Other armoring or groins shall be required to submit environmental impact reports to prove that the structure is the least destructive design in light of its impact on the transport of materials by the waves or currents and effect on other portions of the shoreline.
2. Need: A determination of need shall demonstrate the following:
a. That the property is threatened with erosion damage, and
b. The fill is the minimum needed to stabilize the shoreline and will not add usable land to the site, increase the intensity of use, or permit a building to be closer to the existing shoreline.
3. Water Dependent Uses: All other structures shall be water dependent uses and shall conform to the following standards:
a. The water dependent use is one that cannot function without direct contact with water. Piers, launching ramps and beaches meet this definition.
b. No accessory structures shall be permitted that can be located on the land.
B. Floodplains: Certain water dependent uses must be located in floodplains, and occasionally other uses may be permitted. These may be permitted provided all structures meet the following requirements:
1. General:
a. Only structures which are essential to the water dependent use shall be permitted as of right. Roads and utility crossings shall be permitted only where essential.
b. The structure shall not be designed for human habitation.
c. Any space occupied for the function of the use shall have its floor at least two feet (2') above the flood elevation. All service and utility connections such as water, sewer, electric, or gas, and electrical and heating equipment within the building, shall be similarly located.
2. Structures In Riverine Floodplains:
a. Except for road and utility crossings, no structure shall intrude into the floodway.
b. The structures are constructed and placed on the building site so as to cause an increase of less than one one-hundredth foot (0.01') in flood height off site and offer minimum obstruction to the flow of floodwaters. Floodways should have sufficient clearance between flood elevation and any horizontal structural members to avoid debris jambs.
c. The structures are firmly anchored to prevent them from floating away or collapsing. They shall be certified by an engineer to withstand velocities and likely debris loadings at that point in the floodplain.
3. Structures In Lake Floodplains: The structures are strongly constructed and firmly anchored to prevent them from collapsing under the force of waves or ice. They shall be certified by an engineer to withstand wave and ice actions likely at that location.
4. Fills In Riverine Floodplains: Fills or deposition of materials may be allowed by conditional use permit, provided that:
a. No fill shall be in the floodway or within twenty feet (20') of it.
b. The fill or other materials will be protected against erosion by riprap, vegetative cover, sheet piling, or bulkheading sufficient to prevent erosion.
c. The fill shall be clean fill that is compacted to minimize erosion potential.
d. The fill shall be compensated for so that there is no loss in the cross sectional area of the floodplain and no increase in flood height of more than one one-hundredth foot (0.01') off site.
5. Fills In Water Bodies: Fill in a water body shall be permitted only as a conditional use and only for piers and erosion control structures. The fill volumes shall be the minimum needed to achieve those functions and shall not be used to extend the land area.
C. Wetlands: There are only limited uses of wetlands, and structures such as boardwalks are the only acceptable means of providing access to these areas. There are cases where protection is not a reasonable alternative and where mitigation is an acceptable solution. The following regulations apply to the mitigation of wetland areas to be filled or severely disturbed. In all cases, the mitigation shall be permitted by the U.S. corps of engineers.
1. Mitigation Permitted, Small Depressional Wetlands: Mitigation is permitted only under the following situations:
a. Depressional wetlands of less than one-fourth (0.25) acre may be mitigated.
b. All such areas shall be added to the amount of drainageways on the site and be protected under that standard.
c. Mitigation shall be at a ratio of one to one (1:1).
2. Mitigation Permitted, Advance Identification (ADID) Wetlands: Mitigation shall be permitted only for:
a. Road and utility crossings where alternatives would be substantially inferior in protecting the health and safety of residents; or
b. For structures that will better maintain the hydrology of the wetlands or provide a net gain in wetlands.
c. Mitigation shall be at a ratio of three to one (3:1).
3. Mitigation Permitted, Other Depressional Wetlands: Mitigation shall be permitted as follows:
a. In the SB, CB, LI and LI-2 districts, the intensity of use is so high that retained wetlands of less than two (2) acres will be degraded habitats and isolated wetlands may serve no significant stormwater benefit. Filling shall be permitted where:
(1) Mitigation shall be at a ratio of one and one-half to one (1.5:1).
(2) No more than twenty five percent (25%) of the wetland is designated as high quality.
b. In all other districts, filling involving reconfiguration of the wetlands shall be permitted where:
(1) It can be demonstrated that the wetlands are so located that the developer would not be able to get the permitted number of lots by modifying the plan to avoid the wetlands; or
(2) Where the filling is needed to permit road crossings or drainage control structures.
(3) The mitigation shall be at a ratio of one and one-fourth to one (1.25:1).
4. Mitigation Permitted, Shore Wetlands: A water dependent use, permitted only as a conditional use when it cannot be located elsewhere on the site, shall be permitted to mitigate at a ratio of two to one (2:1).
D. Drainageways: In addition to the open space protection, the total length of the drainageway area shall be kept open to provide a continuous drainage corridor, except where the drainageway is an isolated depressional area not linked to swales or streams. Positive surface drainage in these areas shall be preserved. The protected area may be regraded and reshaped to provide for stormwater detention and drainage. The following standards shall apply:
1. The drainageways shall be used as a natural positive surface drainage system. Where filling is done, it shall not make the drainageway discontinuous. Culverts shall be installed at all road crossings to permit the water to drain.
2. The areas shall be restored to a natural state using seed mixes approved and specified on the village planner's lists.
3. In the design of detention or surface drainage systems in drainageways, the following standards shall govern their design:
a. The drainage shall be designed to slow the time of concentration on the site and retain maximum infiltration into the ground.
b. Where flows permit, the channels shall be designed as grassed swales, wetlands, or mesic grasslands encouraging sheet flow, except in forests.
c. In forests, narrow winding channels shall be used to reduce velocity and avoid trees.
d. All wet basin retention ponds shall be designed to have natural edges using approved plant materials from the village planner's list.
E. Water Body And Wetland Buffers:
1. Calculation Of Natural Resource Area: Water body and wetland buffers shall extend from the edge of the delineated wetland or protected water body. A property may contain a buffer that originates from water bodies or wetlands on adjacent property. The natural resource protection area shall be calculated in the following manner:
a. For wetlands or water bodies with a total surface area of one- third (1/3) acre or greater but less than one acre, a minimum buffer width of thirty feet (30') shall be required.
b. For wetlands or water bodies with a total surface area of one acre or greater, but less than two and one-half (21/2) acres, a minimum buffer width of forty feet (40') shall be required.
c. For wetlands or water bodies with a total surface area of two and one-half (21/2) acres or greater, a minimum buffer width of fifty feet (50') shall be required.
d. High quality aquatic resources shall have a minimum buffer width of one hundred feet (100').
2. Protection Ratio: A minimum of eighty percent (80%) of all required buffer areas shall be protected and maintained as permanent open space unless otherwise expressly provided in this title.
3. Buffer Averaging: The required buffer width for a development site may be varied to a minimum of one-half (1/2) of the buffer width required, upon approval of the planning commission, provided that the total buffer area required is achieved adjacent to the water body or wetland being buffered. The consultation process of the Illinois department of natural resources or U.S. fish and wildlife service may override the ability to average buffer areas upon approval of the planning commission.
4. Protected Areas:
a. Areas having state or federal threatened and endangered species present or for Illinois natural area inventory sites, buffer widths may be modified upon approval of the planning commission to meet the terms and conditions specified during consultation with the Illinois department of natural resources or U.S. fish and wildlife service pursuant to state and federal laws and regulations. However, any additional buffer required pursuant to this provision, shall not affect the site capacity calculation. The planning commission shall support efforts to protect threatened and endangered species whenever such efforts are consistent with the stated purposes of this title.
b. Areas located within one hundred feet (100') from the edge of the delineated wetlands or water body with slopes exceeding twelve percent (12%) grade shall also be protected and maintained as permanent open space unless otherwise expressly provided in this title. The planning commission shall be authorized to allow improvements such as retaining walls to prevent soil erosion and protect public safety within protected steep slope areas. Any additional buffer required pursuant to this provision, shall not affect the site capacity calculation.
c. All existing native vegetation within protected buffer areas shall be left undisturbed. Protected buffer areas may be regraded if the planning commission determines that the regrading is necessary to stabilize the area, prevent soil erosion or otherwise protect or enhance the protected buffer area. The protected buffer area may also be regraded to allow stormwater basins. Access through protected buffer areas shall be provided, when necessary, for maintenance purposes. The protected buffer areas shall be restabilized and revegetated with native vegetation immediately after any disturbance or modification. All runoff will be directed to enter protected buffer areas as unconcentrated flow or will be treated to remove all silt and sediment prior to entering the adjacent wetland. In those very limited and unique circumstances when no other reasonable alternative exists, the planning commission shall be authorized to allow direct runoff into the adjacent wetland.
5. Nonprotected Areas: Buffer areas that are not protected (the remaining 20 percent) may be developed with structures and impervious surfaces including trails and paths.
F. Steep Slopes:
1. Determination And Delineation: Steep slopes are areas of one- fourth (0.25) acre or more where the inclination of the land's surface from the horizontal is thirty percent (30%) or greater and where the vertical rise is at least ten feet (10').
2. Open Space Ratio: Steep slope areas are protected by an open space ratio of 0.85. That is, at least eighty five percent (85%) of all steep slope areas shall be designated and be maintained as permanent open space. The remaining fifteen percent (15%) of all such areas may be developed, regraded or stripped of vegetation.
3. Resource Protection Measures: Steep slope areas requiring protection which lie wholly or partially on site and are within fifty feet (50') of the identified limits of proposed site development activity shall be appropriately marked and fenced to prevent the clearing or stripping of vegetation, the regrading or stockpiling of soil, or the erosion of the ground cover or soil of such protection areas. Such marking or fencing shall be erected at the identified limits of any steep slope area requiring such protection measures.
G. Woodlands: The cutting of trees over a greater area than permitted in section 10-8-2, table IV-C of this chapter is permitted if mitigation is provided and meets the following standards:
1. A tree survey of the entire woodlands on the site is conducted. The best woodlands in terms of percentage of climax vegetation, tree size, tree health, and habitat value shall be preserved. The purpose of the mitigation shall be either:
a. To permit large commercial or industrial type buildings that typically must be a single floor. This does not include grading the entire site, and parking should seek to preserve trees; or
b. To enhance or create a better distribution of woodlands throughout a residential development.
2. The level of protection given woodlands shall not be less than that in table V-E2 of this section.
TABLE V-E2
WOODLAND PROTECTION WITH MITIGATION
Type Of Forest | CBD, LI, LI-2 Districts | All Other Districts | ||
Normal | Mitigation | Normal | Mitigation | |
Mature forest | 0.70 | 0.60 | 0.70 | 0.65 |
Young forest | 0.40 | 0.20 | 0.40 | 0.25 |
3. The land on which the mitigation is to take place shall be on site.
4. Mitigation shall include the planting of one and one-fourth (1.25) acres of new woodland for every one acre of disturbed mature or young woodland for which mitigation is required.
5. Undesirable, nonnative tree species such as Acer negundo (box elder), Robinia pseudoacacia (black locust), Rhamnus cathartica (common buckthorn), Rhamnus frangula (smooth buckthorn), Ailanthus altissima (tree of heaven), Eleagnus angustifolia (Russian olive), Eleagnus umbellata (autumn olive), Populas alba (white poplar) and Ulmus pumila (siberian elm) shall not be considered a natural resource and shall not require protection under this section.
6. Mitigation shall include the replacement of woodlands that have been disturbed with the planting of new woodlands (as specified above) based on a tree survey of the disturbed area (table V-E6 of this section).
TABLE V-E6
STANDARDS FOR REPLACEMENT OF WOODLANDS
STANDARDS FOR REPLACEMENT OF WOODLANDS
dbh Of Canopy Trees Removed | Replacement Canopy Trees | |
Amount | Caliper | |
36" or larger | 5 | 4" |
24" - 35" | 3 | 4" |
16" - 23" | 3 | 3" |
9" - 15" | 2 | 3" |
3" - 8" | 1 | 3" |
H. Protected Resources And Lot Area Calculations:
1. Land area protected under the resource protection and environmental standards of section 10-8-2 of this chapter and this section may not be counted as lot area for the purpose of meeting the minimum lot area standards of section 10-3C-2, table 2 of this title.
2. Land area protected under the resource protection and environmental standards of section 10-8-2 of this chapter and this section must either be dedicated to a village approved public agency or held in common ownership by a property owners' association who shall assume full responsibility for protection and maintenance. The planning commission shall be authorized to recommend and the village board shall be authorized to allow protected resource areas to be located on private lots if:
a. The subdivision consists of nine (9) or fewer lots;
b. All lots have a minimum lot area of at least fifteen thousand (15,000) square feet; and
c. Such authorization does not violate the provisions of subsection H1 of this section. (Ord. 2004-01-01, 1-14-2004; amd. Ord. 2017-02-02, 2-8-2017)