<p><p><h2>Commentary</h2>Typical contract pay items and units of measurement used for geosynthetic in pavement drainage include:<br><ul> <li>Underdrain by the linear foot (LF) – inclusive of appropriate geosynthetic, underdrain conduit, labor, and equipment</li> <li>Pre-fabricated composite drain by the square yard (SY)</li></ul>Granular material may or may not be used in conjunction with geosynthetics in pavement drainage; additional payment for granular material when used is typical. Non-perforated outlet pipes and outlet headwalls are measured and paid for separately. The equipment used to install geosynthetic in pavement drainage is common to highway construction projects; therefore, additional mobilization costs are negligible.<br><h2>Cost Information Summary</h2>Material costs for the geosynthetic, underdrain, and granular material make up the vast majority of total cost. Labor and equipment costs are a function of production rates and project constraints. The following table lists construction cost items associated with geosynthetic in pavement drainage, along with approximate cost ranges. Cost ranges are based on data from 2009 through 2010. Readers should carefully examine the project characteristics and constraints and determine to what degree if any these factors may influence the actual cost associated with installing geosynthetic in pavement drainage.</p><p><table class='tablepress' id='tablepress-96'><thead><th>Pay Item Description</th><th>Quantity</th><th>Unit</th><th>Low Unit Price</th><th>High Unit Price</th><th>Factors Which May Potentially Impact Costs</th></thead><tbody><tr><td >Underdrain (complete-in-place, includes geosynthetic, and drainage conduit)</td><td >Greater Than 2,500</td><td >LF</td><td >$7.00</td><td >$12.00</td><td >Cost range is representative of 6” diameter pipe with 18” x 18” trench
Woven fabrics are more expensive than nonwoven fabrics
Heavier fabrics cost more
Specified lap widths impact the total quantity of material required
Cost increases as the diameter of drainage conduit increases
Cost increases as trench depth increases
</td></tr><tr><td >Pre-Fabricated Composite Drain</td><td >Greater Than 250</td><td >SY</td><td >$20.00</td><td >$45.00</td><td >Material specifications related to fabric type will impact unit costs</td></tr><tr><td >Granular Material</td><td >Greater Than 500</td><td >TON </td><td >$7.00</td><td >$20.00</td><td >Material specifications and haul distance will impact unit costs</td></tr></tbody></table><h2>Historical Cost Information</h2>A sample of actual project costs is shown in the table below.</p><p><table class='tablepress' id='tablepress-97'><thead><th>Pay Item Description</th><th>Quantity</th><th>Unit</th><th>Low Unit Price</th><th>High Unit Price</th><th>Average Unit Price</th><th>No. of Bids</th><th>Bid Date</th><th>Source/Agency</th></thead><tbody><tr><td >4” Pipe Underdrains</td><td >6,200</td><td >LF</td><td >$5.70</td><td >$9.00</td><td >$6.83</td><td rowspan=2 >7</td><td rowspan=2 >11/16/2010</td><td rowspan=2 >Arkansas DOT</td></tr><tr><td >Underdrain Outlet Protectors</td><td >42</td><td >EA</td><td >$250.00</td><td >$465.00</td><td >$340.19</td></tr><tr><td >6” Perforated Pipe Underdrain Round</td><td >73,220</td><td >LF</td><td >$2.00</td><td >$8.50</td><td >$4.84</td><td rowspan=2 >4</td><td rowspan=2 >10/15/2009</td><td rowspan=4 >Oklahoma DOT</td></tr><tr><td >Pipe Underdrain Cover Material</td><td >14,464</td><td >CY</td><td >$25.00</td><td >$50.00</td><td >$33.74</td></tr><tr><td >6” Perforated Pipe Underdrain Round</td><td >3,000</td><td >LF</td><td >$10.00</td><td >$12.00</td><td >$10.49</td><td rowspan=2 >6</td><td rowspan=2 >10/21/2010</td></tr><tr><td >Pipe Underdrain Cover Material</td><td >900</td><td >CY</td><td >$40.00</td><td >$50.60</td><td >$44.28</td></tr><tr><td >Underdrain UD-4</td><td >25,589</td><td >LF</td><td >$7.25</td><td >$9.00</td><td >$8.09</td><td >6</td><td >7/28/2010</td><td >Virginia DOT</td></tr><tr><td >Geocomposite Drain</td><td >5,932</td><td >SY</td><td >$2.51</td><td >$27.78</td><td >$10.78</td><td >7</td><td >3/20/2009</td><td >Georgia DOT</td></tr><tr><td >Perforated Corrugated Polyethylene Underdrain Tubing, 4” Diameter</td><td >23,666</td><td >LF</td><td >$3.05</td><td >$24.38</td><td >$8.43</td><td rowspan=3 >11</td><td rowspan=3 >11/19/2009</td><td rowspan=3 >New York DOT</td></tr><tr><td >Prefabricated Composite Structural Drain</td><td >1,583</td><td >SY</td><td >$8.36</td><td >$41.81</td><td >$26.00</td></tr><tr><td >Prefabricated Composite Integral Abutment Drain</td><td >117</td><td >SY</td><td >$15.05</td><td >$48.50</td><td >$31.47</td></tr></tbody></table><h2>Conceptual Cost Estimating Tool</h2>The conceptual cost estimating tool is intended to be used to develop a preliminary project scoping cost estimate. This preliminary estimate can be based on the typical construction cost item values as contained in the Cost Information product or from user specified cost values when such are known. Users should read and understand the information in Cost Information product prior to using the cost estimating tool. You can download the Cost Estimating Tool to open a cost estimating spreadsheet for producing a preliminary project scoping estimate.</p><p><a class="arrow-link" href="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/… the Cost Estimating Tool</a></p><p> </p></p>
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