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0 <br /> Worksheet 2 Infeasibility Criteria <br /> MINIMUM REQUIREMENT #5 On-Site Stormwater Management <br /> The following tables summarize infeasibility criteria that can be used to justify not using various on-site <br /> stormwater management best management practices (BMPs) for consideration for Minimum Requirement <br /> #5. This information is also included under the detailed descriptions of each BMP in the 2019 SWMM but is <br /> provided here in this worksheet for additional clarity and efficiency. Where any inconsistencies or lack of <br /> clarity exists,the requirements in the main text of the Stormwater Manual shall be applied. <br /> Evaluate the feasibility of the BMPs in priority order based on List #1 or #3. Select the first BMP that is <br /> considered feasible for each surface type. Document the infeasibility (narrative description and rationale)for <br /> each BMP that was not selected. Only one infeasibility criterion needs to be selected for a BMP before <br /> evaluating the next BMP on the list. Attach additional pages for supporting information if necessary. <br /> BMP and Infeasibility description <br /> applicable lists Infeasibility criteria and rationale for each <br /> BMP not selected <br /> T5.13 ❑ Siting and design criteria provided in BMP T5.13 <br /> Postconstruction (Stormwater Manual Volume V,Section 5.3)cannot be achieved. <br /> Soil Quality and ❑ Lawn and landscape area is on till slopes greater than 33 percent. <br /> Depth <br /> BMP and Infeasibility description <br /> applicable lists Infeasibility criteria and rationale for each <br /> BMP not selected <br /> T5.30 ❑ Site setbacks and design criteria provided in BMP T5.30 <br /> Full Dispersion (Stormwater Manual Volume V,Section 5.3)cannot be achieved. <br /> E A 65 to 10 ratio of forested or native vegetation area to <br /> impervious area cannot be achieved. <br /> ❑ A minimum forested or native vegetation flowpath length of 100 <br /> feet(25 feet for sheet flow from a non-native pervious surface) <br /> cannot be achieved. <br /> T5.10A ❑ Evaluation of infiltration is not required per the Infiltration <br /> Downspout Infeasibility Map due to steep slopes,erosion hazards,or <br /> Full Infiltration landslide hazards. <br /> ❑ Site setbacks and design criteria provided in BMP T5.10A <br /> (Stormwater Manual Volume III,Section 3.1.1)cannot be <br /> achieved. <br /> ❑ The lot(s)or site does not have out-wash or loam soils. <br /> ❑ There is not at least 3 feet or more of permeable soil from the <br /> proposed final grade to the seasonal high groundwater table, <br /> hardpan layer,or other impermeable layer. <br /> ❑ There is not at least 1 foot or more of permeable soil from the <br /> proposed bottom of the infiltration system to the seasonal high <br /> groundwater table,hardpan layer,or other impermeable layer. <br /> City of Everett Public Works <br /> Small Project Stormwater Site Plan Report-Dec 2019 25 <br />