Volume 2-05, Chapter 3 - City of Wichita

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Section 3.2.1 - Stomwater Pond more than 10%, and be appropriately stabilized to withstand maintenance equipment and vehicles. • When required, reserves and/or drainage easements must extend to the forebay, safety bench, riser, and outlet and, to the extent feasible, be designed to allow vehicles to turn around. • Access to the riser is to be provided by lockable manhole covers, and manhole steps should be within easy reach of valves and other controls. H. SAFETY FEATURES • All embankments and spillways must be designed to State of Kansas guidelines for dam safety, where applicable. • Fencing of ponds may be required in some cases by the local review authority. In lieu of fencing, one method is to manage the contours of the pond through the inclusion of a safety bench (see above) to eliminate dropoffs and reduce the potential for accidental drowning. In addition, the safety bench can be landscaped to deter access to the pool. • The spillway openings (riser and outlet barrel) should be protected to prevent entry by children. Endwalls above pipe outfalls greater than 36 inches in diameter should be fenced to prevent access and subsequent fall hazards. I. LANDSCAPING • Aquatic vegetation can play an important role in pollutant removal in a stormwater pond. In addition, vegetation can enhance the appearance of the pond, stabilize side slopes, serve as wildlife habitat, and can temporarily conceal unsightly trash and debris. Therefore, wetland plants should be encouraged in a pond design, along the aquatic bench (fringe wetlands), the safety bench and side slopes (ED ponds), and within shallow areas of the pool itself. The best elevations for establishing wetland plants, either through transplantation or volunteer colonization, are within 6 inches (plus or minus) of the normal pool elevation. • Woody vegetation may not be planted on the embankment or allowed to grow within 15 feet of the toe of the embankment and 25 feet from the principal spillway structure (tree exclusion zone). • Where practicable, a pond buffer should be provided that extends 25 feet outward from the maximum water surface elevation of the pond. The pond buffer should be contiguous with other buffer areas that are required by existing regulations (e.g., stream buffers) or that are part of the overall stormwater management concept plan. No structures should be located within the buffer. • Existing trees should be preserved in the buffer area during construction in areas where the minimum distance requirements of the previous paragraph (tree exclusion zone) can be satisfied. It is desirable to locate conservation areas adjacent to ponds. The buffer can be planted with trees, shrubs and native ground covers. • Selected fish species can be stocked in a pond to aid in mosquito prevention. Page 3 - 36 Volume 2, Technical Guidance
Section 3.2.1 - Stormwater Pond • A fountain or solar-powered aerator may be used for oxygenation of water in the permanent pool if required to sustain fish. • Compatible multi-objective use of stormwater pond locations is encouraged. J. ADDITIONAL SITE-SPECIFIC DESIGN CRITERIA AND ISSUES Physiographic Factors - Local terrain design constraints Low Relief: Maximum normal pool depth is limited; providing pond drain can be problematic; High Relief: Embankment heights may be restrictive; Karst: Requires poly or clay liner to sustain a permanent pool of water and protect aquifers; limits on ponding depth; geotechnical tests may be required. Soils • Hydrologic group “A” soils, and some “B” soils, require pond liner. Special Downstream Watershed Considerations Local Sensitive Downstream Aquatic Habitat: Extended detention micropool pond is the best alternative to minimize or eliminate impacts due to warm water discharges when sensitive aquatic habitat is located downstream of the pond. For wet ponds and extended detention wet ponds, consider providing off-line WQ V treatment to reduce the size of pond or if possible, design a smaller, but deeper pond, with vegetation surrounding the pond to provide solar shading and minimize thermal impacts. Aquifer Protection: Reduce potential groundwater contamination by pretreating hotspot runoff prior to hotspot runoff entering pond. May require liner for type “A” and “B” soils. Dams The most commonly used material for small dam construction is earth fill, but structural concrete can also be used. For on-site stormwater controls in high density areas of development or where land values are very costly, the use of a structural concrete dam can save a significant amount of land and in some cases make a more aesthetically appealing outfall structure than the typical riser and barrel assembly. The following are general guidelines for the construction of detention pond dams. Where applicable, the construction specifications should be provided by a Professional Engineer of Record for the dam design. • General • The dam area shall be cleared, grubbed and stripped of all vegetative material and topsoil prior to dam construction. Volume 2, Technical Guidance Page 3 - 37
Page 1 and 2: CHAPTER 3 STORMWATER CONTROLS TABLE
Page 3 and 4: Chapter 3 - Table of Contents 3.2.8
Page 5 and 6: Chapter 3 - Table of Contents LIST
Page 7 and 8: Section 3.1 - Stormwater Management
Page 31 and 32: Section 3.2.1 - Stormwater Pond 3.2
Page 33 and 34: Section 3.2.1 - Stormwater Pond Fig
Page 35 and 36: Section 3.2.1 - Stormwater Pond For
Page 37 and 38: Section 3.2.1 - Stormwater Pond •
Page 39 and 40: Section 3.2.1 - Stormwater Pond 1'
Page 41: Section 3.2.1 - Stormwater Pond •
Page 45 and 46: Section 3.2.1 - Stormwater Pond 3.2
Page 47 and 48: Section 3.2.1 - Stormwater Pond Ste
Page 53 and 54: Section 3.2.2 - Extended Dry Detent
Page 59 and 60: Section 3.2.3 - Vegetative Filter S
Page 67 and 68: Section 3.2.4 - Grassed Channel 3.2
Page 73 and 74: Section 3.2.4 - Grassed Channel max
Page 75 and 76: Section 3.2.5 - Enhanced Swale 3.2.
Page 77 and 78: Section 3.2.5 - Enhanced Swale Chan
Page 79 and 80: Section 3.2.5 - Enhanced Swale B. G
Page 81 and 82: Section 3.2.5 - Enhanced Swale High
Page 83 and 84: Section 3.2.5 - Enhanced Swale Side
Page 85 and 86: Section 3.2.5 - Enhanced Swale 3.2.
Page 87 and 88: Section 3.2.6 - Infiltration Trench
Page 93 and 94:
Section 3.2.6 - Infiltration Trench
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Page 97 and 98:
Page 99 and 100:
Section 3.2.7 - Soakage Trench 3.2.
Page 101 and 102:
Section 3.2.7 - Soakage Trench •
Page 103 and 104:
Section 3.2.8 - Surface Sand Filter
Page 105 and 106:
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Page 111 and 112:
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Page 115 and 116:
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Section 3.2.9 - Bioretention Areas
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Section 3.2.10 - Stormwater Wetland
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Section 3.3 - Secondary TSS Treatme
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Section 3.3.1 - Proprietary Treatme
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Section 3.3.1 - Proprietary Treatme
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Section 3.3.2 - Gravity (Oil-Water)
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Section 3.3.3 - Alum Treatment 3.3.
Page 165 and 166:
Section 3.3.3 - Alum Treatment •
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Section 3.3.4 - Underground Sand Fi
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Section 3.3.5 - Organic Filter 3.3.
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Section 3.3.5 - Organic Filter •
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Section 3.4 - Other Stormwater Mana
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Section 3.4.1 - Conventional Dry De
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Section 3.4.2 - Underground Dry Det
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Section 3.4.3 - Porous Pavement 3.4
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Section 3.4.3 - Porous Pavement The
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Section 3.4.3 - Porous Pavement com
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Section 3.4.3 - Porous Pavement Fig
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Section 3.4.4 - Modular Porous Pave
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Section 3.4.5 - Green Roof 3.4.5 Gr
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Section 3.4.5 - Green Roof Signific
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Section 3.4.5 - Green Roof 3.4.5.3
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Volume 2-05, Chapter 3 - City of Wichita

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