20230125 Environmental Board Packet Combined

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Shenandoah Improvements Feasibility Report City of Lino Lakes, MN WSB Project No. 018901-000 Page 9 Construction Cost - Option 1 Description Units Contract Quantity Unit Price Total Price Comments MOBILIZATION LS 1 $10,000 $10,000 ~10% of total budget COMMON EXCAVATION C Y 3000 $17.50 $52,500 Essentially all cut and removal from site RANDOM RIPRAP CL III C Y 20 $120.00 $2,400 For inlets 12" RCP L F 190 $90 $17,100 Based on OneOffice 12" RCP APRON EACH 2.00 $1,500 $3,000 Based on OneOffice FLAP GATE/DUCKBILL VALVE EACH 2.00 $3,000 $6,000 Based on OneOffice, no duckbill estimate STABILIZED CONSTRUCTION ENTRANCE EACH 1.00 $1,500 $1,500 Likely off Arrowhead Dr SILT FENCE L F 810 $3.50 $2,835 Need around grading + 40' to double up at culvert outlet EROSION CONTROL BLANKET S Y 3000 $3 $9,000 Placed on all pond slopes (top contour area - bottom contour area) SEEDING ACRE 1.4 $2,000 $2,800 Assume seeding occurs within full limits of disturbance plus over access route SEED MIX 25-151 LB 24 $10 $240 Seeding over access road SEED MIX 34-261 LB 40 $75 $3,000 Seeding wetland/pond areas 1.5" CAL TREE - BALLED AND BURLAPPED TREE 60 $400 $24,000 Based on OneOffice SHRUB - 5 GAL POT SHRB 100 $75 $7,500 Based on OneOffice 5 YEAR MONITORING/MAINTENANCE LS 1 $42,880 $42,880 20% Contingency $28,375 Total:$170,250 It does afford space for a pathway between th e wetlands and educational interaction points. Concept 1 generally works , but can be improved upon to achieve the greatest site benefits. 6.1 Modeling Results TSS Removal (lb/yr) TP Removal (lb/yr) Ditch 100 -yr HWL HWL Decrease (ft) 758 4.21 891.43 0.72 The results above are based on the P8 and InfoSWMM modeling for this project. The proposed wetland basins provided water quality improvements in accordance with their footprint and volume, TSS and TP removals shown are increases over existing modeled pollu tant removals. The drop in ditch high water level is also a function of basin volume. As such, Concept 1 shows the least benefits of all options due to its smaller basin footprint. 6.2 Construction Estimate The main driver of costs for all the provided concept s are excavation costs. Concept 1 calls for approximately 3000 cubic yards of excavation, driving about 50 percent of the construction costs. Other major costs include the construction of associated storm sewer and vegetation restoration across the site. T he total estimated concept cost, including a 20 percent cost contingency, is $170,250. Monitoring and maintenance of the site’s natural resources will be key to establishing a diverse, native plant community. Site maintenance includes a minimum of two sit e visits (spring and fall) for five years to conduct mowing and herbicide spot treatments, and supplemental seeding during one of the recommended five years. The cost of maintenance for five years as described is $34,380. Monitoring the vegetation each yea r would provide the C ity with an adaptive management approach to maintenance. The cost of monitoring one time per year for five years is $8,500.