GREEN INFRASTRUCTURE RESOURCE GUIDE | 11 PRE-PLANNING AND ASSESSMENT plains, riparian areas, and topography are all common features to consider. Cultural and historic elements must be considered along with other existing site features. SOILS – Existing soil types and textures can impact infiltration rates (i.e., the ability for stormwater to soak down into the soil). Clay soils and urban soils, for example, have low infiltration rates. Common characteristics of urban soils include high soil compaction, low organic matter content, and soil contamination.30 The presence of existing pavement, bare spots, scouring, exposed/above ground roots, construction debris, and the quality of existing vegetation can all provide visual clues of soil conditions. These observations can be verified with professional laboratory and field tests. Such factors do not rule out green stormwater infrastructure, but they do need to be kept in mind during planning. Techniques such as soil remediation or amending the soil, de-compacting soils, and minimizing clogging of pores can improve performance and infiltration.31 Your local Soil Conservation District (SCD) representative may be helpful in assessing soil characteristics. VACANT LANDS AND BROWNFIELDS – Vacant sites and brownfields (land previously used for industrial or commercial purposes where the presence of contaminants is likely) provide viable options for park development projects. However, care should be taken to ensure that contaminants or waste materials in the soil are abated without increasing the risk of groundwater contamination. Visual examinations of the site should be coupled with a thorough examination of historic property and environmental records. An environmental investigation of the property is typically required prior to property transfers. This may include collecting and testing surface and subsurface soil samples and groundwater samples.32 In some cases, brownfield remediation can provide motivation and funding for park development. In Atlanta, Georgia, Historic Fourth Ward Park was built on a former industrial area, and uses a high-capacity stormwater detention pond in addition to smaller green stormwater infrastructure practices to treat polluted runoff and reduce flooding. Park development included numerous play areas and trails connecting to other amenities around the city.33 ACCESS TO WATER FOR IRRIGATION – The need or potential need for occasional irrigation of green stormwater infrastructure plantings can be limiting factors for arid and semiarid regions. In addition, new plants in need of establishment may require supplemental irrigation. It is important to be aware of water access on the intended site and how to meet these needs upfront. Irrigation requirements can be reduced by using native, drought-tolerant plants, amending the soil, proper mulching, utilizing rainwater harvested on-site with rain barrels or cisterns, and proper maintenance.34 Consult local and state regulations, if applicable, for restrictions on water harvesting related to issues such as water-quality, public health concerns, and existing water-rights laws.35 CLIMATIC CONDITIONS – Local climates affect the performance of green stormwater infrastructure installations. Tailoring designs to account for climatic extremes can help avoid negative impacts. For example, cold weather can impact the structural integrity of devices such as permeable pavement. However, with proper siting, material selection, and maintenance, porous asphalt can perform very well in cold climates.36 Green infrastructure practices in arid climates require different types of vegetation than those in more temperate areas, and may be used to address different needs. Green infrastructure may be used to conserve water or to stabilize soil to prevent erosion and reduce drought susceptibility.37 Green stormwater infrastructure can aid in groundwater recharge, which may provide an additional source of funding.
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