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Modeling Results <br />TSS Removal <br />(lb/yr) <br />TP Removal <br />(lb/yr) <br />Ditch 100-yr HWL <br />HWL Decrease (ft) <br />1,416 <br />9.05 <br />891.28 <br />0.87 <br />The results above are based on the P8 and InfoSWMM modeling for this project. The <br />proposed wetland basins provided water quality improvements in accordance with <br />their footprint and volume, TSS and TP removals shown are increases over existing <br />modeled pollutant removals. The drop in ditch high water level is also a function of <br />basin volume. As such, Concept 2 shows the greatest benefits of all options due to <br />its largest basin footprint. <br />7.2 Construction Estimate <br />Again, the main driver of costs is excavation, even more so for this concept since <br />basin size is maximized. Concept 2 calls for nearly 15,000 cubic yards of <br />excavation, driving about 80 percent of the construction costs. As with Concept 1, <br />other major costs include the construction of associated storm sewer and vegetation <br />restoration across the site. The total estimated concept cost, including a 20 percent <br />cost contingency, is $410,000. <br />Monitoring and maintenance of the site's natural resources will be key to <br />establishing a diverse, native plant community. Site maintenance includes a <br />minimum of two site visits (spring and fall) for five years to conduct mowing and <br />herbicide spot treatments, and supplemental seeding during one of the <br />recommended five years. The cost of maintenance for five years as described is <br />$34,380. Monitoring the vegetation each year would provide the City with an <br />adaptive management approach to maintenance. The cost of monitoring one time per <br />year for five years is $8,500. <br />Construction Cost - Option 2 <br />Description <br />Units <br />Contract Quantity <br />Unit Price <br />Total Price <br />Comments <br />MOBILIZATION <br />LS <br />1 <br />$20,000 <br />$20,000 <br />"'10%oftotalbudget, slightly lower b/csimpler <br />COMMON EXCAVATION <br />C Y <br />14750 <br />$17.50 <br />$258,125 <br />Essentially all cut and removal from site <br />RANDOM RIPRAP CL III <br />C Y <br />10 <br />$120.00 <br />$1,200 <br />For inlets <br />12" RCP <br />L F <br />70 <br />$90 <br />$6,300 <br />Based on OneOffice <br />12" RCP APRON <br />EACH <br />2.00 <br />$1,500 <br />$3,000 <br />Based on OneOffice <br />FLAP GATE/DUCKBILL VALVE <br />EACH <br />2.00 <br />$3,000 <br />$6,000 <br />Based on OneOffice, no duckbill estimate <br />STABILIZED CONSTRUCTION ENTRANCE <br />EACH <br />1.00 <br />$1,500 <br />$1,500 <br />Likely off Arrowhead Dr <br />SILT FENCE <br />LF <br />1,060 <br />$3.50 <br />$3,710 <br />Need around grading + 40'to double up at <br />culvert outlet <br />EROSION CONTROL BLANKET <br />S Y <br />3620 <br />$3 <br />$10,860 <br />Placed on all pond slopes (top contour area - <br />bottom contour area) <br />SEEDING <br />ACRE <br />1 2.6 <br />$2,000 <br />$5,200 <br />Assume seeding occurs within full limits of <br />disturbance plus over access route <br />SEED MIX 25-151 <br />LB <br />24 <br />$10 <br />$240 <br />Seeding over access road, 120 lb/ac <br />SEED MIX 34-261 <br />LB <br />80 <br />$75 <br />$6,000 <br />Seeding wetland/pond areas, 31.5lb/ac <br />1.5" CALTREE - BALLED AND BURLAPPED <br />TREE <br />30 <br />$400 <br />$12,000 <br />Based on OneOffice <br />SHRUB - 5 GAL POT <br />SHRB <br />100 <br />$75 <br />$7,500 <br />Based on OneOffice <br />5 YEAR MONITORING/MAINTENANCE <br />LS <br />1 <br />$42,880 <br />$42,880 <br />20%Contingency 1 68,327 <br />Total: 1 $409,962 <br />Shenandoah Improvements Feasibility Report <br />City of Lino Lakes, MN <br />WSB Project No. 018901-000 <br />Page 12 <br />