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(1) Determine the total volume of runoff from a one -year frequency, twenty - <br />four hour storm, occurring on the development area before and after develop- <br />ment. <br />(2) From the volumes in paragraph (A) determine the percent of increase in <br />volume of runoff due to development and, using this percentage, select the criti- <br />cal storm from this table: <br />Table 4: Critical Storm Selection <br />Equal To Or Greater Than <br />And Less Than <br />The 24- <br />Hour "Crit- <br />ical Storm" <br />For Dis- <br />chargeis <br />0 <br />10 <br />1 Year <br />10 <br />20 <br />2 Years <br />20 <br />50 <br />5 Years <br />50 <br />100 <br />10 Years <br />100 <br />250 <br />25 Years <br />250 <br />500 <br />50 Years <br />500 <br />- -- <br />100 Years <br />(e) Detention Or Retention Basin Exemption For Redevelopment Or For Ex- <br />pansion Of Existing Facilities. <br />(1) For any development regulated by this chapter, the construction of a deten- <br />tions or retention basin may not be required for the development if the post - <br />development peak discharge for a 100 year frequency 24 hour storm increases <br />the existing peak discharge by one (1) cubic foot per second or less using the <br />TR -55 method of calculation or other method approved by the City Engineer. <br />The City Engineer can waive this requirement if existing storm sewers and <br />drainage structures can safely handle the expected increase in flow. <br />(2) Only one (1) exemption will be allowed per parcel. Any subsequent expan- <br />sion must provide for detention or retention and must include the previously ex- <br />empted area. <br />(f) Where the City Engineer determines that site constraints exist in a manner <br />that compromises the intent of this chapter to improve the management of storm <br />water runoff as established in this section, practical alternatives may be used to <br />result in an improvement of water quality and/or a reduction of storm water run- <br />off. Such alternatives must be in keeping with the intent and likely cost of those <br />measures that would otherwise be required to meet the objectives of this section. <br />When possible, all practical alternatives shall be implemented within the drain- <br />age area of the proposed development project. Practical alternatives can in- <br />clude, but are not limited to: <br />(1) Fees paid in an amount specified by the City of Lakewood, which shall be <br />applied by the City of Lakewood to storm water management practices; <br />21 <br />