20230104 Environmental Board Packet Combined

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Shenandoah Improvements Feasibility Report City of Lino Lakes, MN WSB Project No. 018901-000 Page 12 Construction Cost - Option 2 Description Units Contract Quantity Unit Price Total Price Comments MOBILIZATION LS 1 $20,000 $20,000 ~10% of total budget, slightly lower b/c simpler COMMON EXCAVATION C Y 14750 $17.50 $258,125 Essentially all cut and removal from site RANDOM RIPRAP CL III C Y 10 $120.00 $1,200 For inlets 12" RCP L F 70 $90 $6,300 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 1,060 $3.50 $3,710 Need around grading + 40' to double up at culvert outlet EROSION CONTROL BLANKET S Y 3620 $3 $10,860 Placed on all pond slopes (top contour area - bottom contour area) SEEDING ACRE 2.6 $2,000 $5,200 Assume seeding occurs within full limits of disturbance plus over access route SEED MIX 25-151 LB 24 $10 $240 Seeding over access road, 120 lb/ac SEED MIX 34-261 LB 80 $75 $6,000 Seeding wetland/pond areas, 31.5 lb/ac 1.5" CAL TREE - BALLED AND BURLAPPED TREE 30 $400 $12,000 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 $68,327 Total:$409,962 7.1 Modeling Results TSS Removal (lb/yr) TP Removal (lb/yr) Ditch 100 -yr HWL HWL Decrease (ft) 1,416 9.05 891.28 0.87 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 pollutant removals. The drop in ditch high water level is also a function of basin volume. As such, Concept 2 shows the greate st benefits of all options due to its largest basin footprint. 7.2 Construction E stimate Again, the main driver of costs is excavation, even more so for this concept since basin size is maximized . Concept 2 calls for nearly 15,000 cubic yards of excavation, dr iving about 8 0 percent of the construction costs. As with Concept 1, o ther major costs include the construction of associated storm sewer and vegetation restoration across the site. The total estimated concept cost , including a 20 percent cost contingency, is $410,000 . 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 site 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 year would provide the C ity with an adaptive management approach to maintenan ce. The cost of monitoring one time per year for five years is $8,500.