Phase A - Alternatives Analysis Report - Urban Drainage and Flood ...

PHASE A – ALTERNATIVES ANALYSISMajor Drainageway Planning Update for Hidden Lake-Bates LakeStructuralImprovementsTrafficControlAlternative PlanREACH H-1: Watershed Headwaters to Sheridan Boulevard5aUtilityRelocationsPropertyAcquisitionEngineering, CM,& ContingenciesOperation &MaintenanceAlternativeTotal CostsTotalAnnualizedDamages *Total AnnualizedDamages AfterMitigationBenefit-Cost RatioConstruct detention basinwith water quality in openImproves water quality,space at the ArvadaCenter. & Upsize box $965,596 $89,975 $59,983 $15,585 $337,959 $47,000 $1,516,098 $384,670 $0 2.51 eliminates structural damage inculvert under Sheridanthe 100-year event, andBlvd. Raise the Graceeliminates overtopping ofChurch access road andinstall a box culvert.Sheridan Boulevard in the 100-year event.REACH H-2: Hidden Lake4a Construct wetland east ofSheridan Blvd, south of $200,272 $0 $0 $0 $70,095 $10,000 $280,367 0.0069th Ave.Improves water quality.REACH H-3: Between Hidden Lake & Lake Sangraco along Lowell Blvd.3a Upsize the elliptical pipesEliminates flooding of Lowell$127,583 $6,379 $12,758 $0 $44,654 $3,000 $194,374 $334 $0 0.02under 66th Ave.Boulevard in the 100-year event.4a Remove the low flowconcrete channel andreplace with soil riprap and$107,460 $5,373 $0 $0 $37,611 $4,000 $154,443 0.00check structures.Improves water quality.REACH H-4: Lake Sangraco to Clear Creek1a Do nothing $0 $0 $0 $0 $0 $0 $0 0.00REACH B-1: Watershed Headwaters to Railroad Tracks at Sheridan Boulevard2a Construct a formal outlet inBates Lake / HomesteadPark.$33,600 $1,680 $0 $0 $11,760 $4,000 $51,040 Improves safety in HomesteadPark.5aCombination ofAlternatives 2b, 4c, 3a &3b.$782,896 $63,752 $71,021 $108,000 $274,014 $29,000 $1,328,683 $413,710 $180,078 1.77Reach B-2: Along Railroad Tracks from Sheridan Boulevard to Tennyson Street1a Do nothingTotal$0 $0 $0 $0 $0 $0 $0 0.00$2,217,406 $167,159 $143,763 $123,585 $776,092 $97,000 $3,525,006 $798,714 $180,078* Values include Flooding Damages and Loss of Function due to flooding within each reach.Table 7-1 Recommended Plan Cost Estimate and Benefit RatiosNotesImproves water quality,eliminates structural damage inthe 100-year event, andeliminates overtopping ofTennyson Street in the 100-yearevent.The recommended imprvementsin Reach B-1 will eliminateflooding within Reach B-2 andalso eliminate overtopping ofTennyson Street in the 100-yearevent.7-2