North Peoria Area Drainage Master Plan - Flood Control District of ...

Table 4Summary of Evaluation Results Stormwater Storage Based AlternativesPlanningAreaEvaluationCriteriaWeightingFactorIn-Stream, Off-LineRetentionIn-Stream, In-LineDetentionRating Score Rating Score1 2 3 4 5 6 7Big Spring Public Safety 10 7 68 6 64Social 3 11 34 10 31Environmental 6 10 60 9 53Economic 4 6 24 6 24Total Score = 186 172hour event is not practical. Scoring results forthe stormwater storage are listed in Table 4.PREFERRED FLOOD CONTROL MANAGEMENTALTERNATIVESThe preferred watercourse-based flood controlmanagement alternative is the non-structuralalternative. The non-structuralalternative defines a corridor that allows thewatercourse to function naturally and isdefined by the 100-year floodplain, erosionhazard zone and a buffer if applicablebetween human activity and a wash corridor.The plan recognizes that there may be situationsin which development activities may berequired or desired within the erosion hazardzone, for this situation the plan presents a lowimpact structural alternative. Channelizationis not a preferred flood control managementalternative; however, the plan also recognizesthat there may be situations in which channelizationmay be required. The preferred stormwaterstorage alternative is the standardpractice of retaining the volume from the 100-year, 2-hour rainfall event, however this practicemay not be practical for certain portions ofthe study area. The standard retention practicesif implemented within an entire watershedwould have negative impacts in regardsto sustaining native vegetation along watercourses.The plan offers two stormwaterreduction alternatives to the standard practice.The stormwater storage alternatives are basedon reducing post-development peak dischargesto pre-development magnitudes. Thealternatives are referred to as the in-stream,off-line retention alternative and in-stream, inlinedetention alternative. The in-stream, offlineretention is the preferred alternative of thetwo.COMPATIBILITY WITH OTHERPLANNING DOCUMENTSComponents of preferred flood control managementalternatives are compared to componentsof environmental resources, safety, andopen space elements of other planning documentsto ensure that there is consistencybetween the intent of the North Peoria ADMPand the intent of other planning documents.Table 5 lists the themes of objectives and policiesfrom the North Peoria ADMP and otherapplicable planning documents that have similargoals.19