Culvert Replacement Cost Benefits in the Long Term

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1 Culvert Replacement Cost Benefits in the Long Term Ben Naumann 1 Lynn Knight 2 1 NRCS Fisheries Biologist, Bangor ME 2 NRCS Economist, Greensboro NC Technical Center

2 Stream- Smart Crossings Maintain fish and wildlife habitat while protecting roads and public safety.

3 Stream- Smart crossing Con s Cost Cost Cost Cost Invasive species Pro s Environmental Healthier popula7ons of fish Decreased erosion of stream banks Improved water quality Public safety Economic Recrea7on Jobs Climate change Long term cost benefits?

4 Long Term Cost Benefits? Table 5. Eastern Maine Culvert Cost Estimates (2007 dollars) Average annual cost over 50 Scenario Description year time- frame Arch culvert Round culvert Case 1 10' x 4'5" arch replaces two 2.5' round culverts $ 1,357 $ 1,706 Case 2 12' x 5' arch replaces 3.5' round culvert $ 1,545 $ 1,887 Case 3 12' x 5' arch replaces 3' round culvert $ 2,265 $ 1,461 Case 4 12' x 5' arch replaces 4' round culvert $ 2,452 $ 2,000 Estimated Average Annual Cost for Lewis Brook Culvert (2012 Dollars) Annual cost over 15 years Annual cost over 35years Annual cost over 70 years Double Metal Pipe Culvert $ 6,551 $ 4,446 $ 2,726 Concrete Box Culvert $ 13,533 $ 5,800 $ 2,900 Exis,ng analysis on structure comparison costs Forestry roads Long compared arch culverts Municipal roads An Economic Analysis of Improved Road- Stream Crossings TNC

5 Long Term Cost Benefits? Table 5. Eastern Maine Culvert Cost Estimates (2007 dollars) Average annual cost over 50 Scenario Description year time- frame Arch culvert Round culvert Case 1 10' x 4'5" arch replaces two 2.5' round culverts $ 1,357 $ 1,706 Case 2 12' x 5' arch replaces 3.5' round culvert $ 1,545 $ 1,887 Case 3 12' x 5' arch replaces 3' round culvert $ 2,265 $ 1,461 Case 4 12' x 5' arch replaces 4' round culvert $ 2,452 $ 2,000 Estimated Average Annual Cost for Lewis Brook Culvert (2012 Dollars) Annual cost over 15 years Annual cost over 35years Annual cost over 70 years Double Metal Pipe Culvert $ 6,551 $ 4,446 $ 2,726 Concrete Box Culvert $ 13,533 $ 5,800 $ 2,900 Addi,onal analysis need: Compare costs over 7me for difference structure types for forestry crossings over 50 years More cost examples from Maine specifically for municipali7es Two case studies Forestry Municipali7es

6 Forestry Case Study

7 Forestry Case Study Four Structure types compared: Waste block bridge: Inside span 14 actual cost $10,200 Maintenance schedule: Running boards every 10 yrs, 8x8 every 20 yrs Arch culvert: 10x6.3x40 es7mated cost $35,400 Maintenance schedule: None CMP Culvert 4 : Es7mated cost 4,000 note, doesn t meet current BMP s Maintenance schedule: Annual $600, Culvert replacement every 20 yrs 2 PVC Culverts 4 : Es7mated cost $9,600 Meets current BMP s for 25 yr storm Maintenance schedule: Annual 600, Culverts not replaced

8 Forestry Case Study Present Value Analysis bringing all future payments to the present (today) answers the ques7on: How do I objec7vely compare alterna7ves with differing up- front installa7on costs, and future O&M costs? Infla7on rate of 2.8 percent Average Annual answers the ques7on: If I had to borrow money up front to install and maintain the various alterna7ves, how much would I need to borrow, and what would the annual loan payments be?

9 Forestry Case Study Altera,ve Structure Net Present Value Average Annual Cost 1 Arch Culvert $35,400 $1, Plas7c Culverts $25,642 $959 3 Round Culvert $23,670 $885 4 Bridge $13,640 $510

10 Forestry Case Study Altera,ve Structure Net Present Value Average Annual Cost 1 Arch Culvert $35,400 $1, Plas7c Culverts $25,642 $959 3 Round Culvert $23,670 $885 4 Bridge $13,640 $510 5 Bridge $11,426 $427

11 Municipal Case Study

12 Municipal Case Study Structure types compared: CMP Culvert: 6 with a 2 foot over flow Actual maintenance schedule: 500 every other year, $10,000 large repair at 20 yrs, culvert replaced 28 yrs Concrete Box Culvert: Actual cost $164,000 Maintenance schedule: None, 75 yrs lifespan

13 Municipal Case Study Alterna,ve Structure Net Present Value Average Annual Cost 1 6 culvert $135,274 $4,317 2 Concrete Culvert $164,000 $5,234

14 Big storms will become increasingly likely 43% Extreme storms

15 Conclusion Forestry case study: bridges were the most cost savings over7me regardless of maintenance Municipal case study: Short term concrete box is much more expensive, annual costs between the two structure type become less as lifespan increases Future analysis could include: catastrophic failures, climate change, and human safety. Addi7onal project comparisons are needed from the state Request for an on- line municipality data repository for keeping track of maintenance, replacement dates and costs

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