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It does afford space for a pathway between the wetlands and educational interaction <br />points. Concept 1 generally works, but can be improved upon to achieve the greatest <br />site benefits. <br />6.1 Moaelling Kesults <br />TSS Removal <br />(lb/yr) <br />TP Removal <br />(lb/yr) <br />Ditch 100-yr HWL <br />HWL Decrease (ft) <br />758 <br />4.21 <br />891.43 <br />0.72 <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 1 shows the least benefits of all options due to its <br />smaller basin footprint. <br />6.2 Construction tstimate <br />The main driver of costs for all the provided concepts are excavation costs. Concept <br />1 calls for approximately 3000 cubic yards of excavation, driving about 50 percent of <br />the construction costs. Other major costs include the construction of associated <br />storm sewer and vegetation restoration across the site. The total estimated concept <br />cost, including a 20 percent cost contingency, is $170,250. <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 1 <br />Description <br />Units <br />Contract Quantity <br />Unit Price <br />Total Price <br />Comments <br />MOBILIZATION <br />LS <br />1 <br />$10,000 <br />$10,000 <br />—10•� of total budget <br />COMMON EXCAVATION <br />CY <br />3000 <br />$17.50 <br />$52,500 <br />Essentially all cut and removal from site <br />RANDOM RIPRAP CL III <br />CY <br />20 <br />$120.00 <br />$2,400 <br />For inlets <br />12" RCP <br />L F <br />190 <br />$90 <br />$17,100 <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 />1 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 />810 <br />$3.50 <br />$2,835 <br />Need around grading+40'to double up at <br />culvert outlet <br />EROSION CONTROL BLANKET <br />SY <br />3000 <br />$3 <br />$9,000 <br />Placed on all pond slopes (top contour area - <br />bottom contour area) <br />SEEDING <br />ACRE <br />1.4 <br />$2,000 <br />$2,800 <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 <br />SEED MIX 34-261 <br />LB <br />40 <br />$75 <br />$3,000 <br />Seeding wetland/pond areas <br />1.5" CAL TREE - BALLED AND BURLAPPED <br />ITREE <br />60 <br />$400 <br />$24,000 <br />Based on OneOffice <br />SHRUB - 5 GAL POT <br />ISHRB <br />100 <br />$75 <br />$7,500 <br />Based on OneOffice <br />5 YEAR MON ITORI NG/MAI NTENANCE <br />I LS <br />1 <br />$42,980 <br />$42,880 <br />20% Contingency 1 $28,375 <br />Total: 1 $170,250 <br />Shenandoah Improvements Feasibility Report <br />City of Lino Lakes, MN <br />WSB Project No. 018901-000 <br />Page 9 <br />