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
Stream- Smart Crossings Maintain fish and wildlife habitat while protecting roads and public safety.
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?
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
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
Forestry Case Study
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
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?
Forestry Case Study Altera,ve Structure Net Present Value Average Annual Cost 1 Arch Culvert $35,400 $1,324 2 2 Plas7c Culverts $25,642 $959 3 Round Culvert $23,670 $885 4 Bridge $13,640 $510
Forestry Case Study Altera,ve Structure Net Present Value Average Annual Cost 1 Arch Culvert $35,400 $1,324 2 2 Plas7c Culverts $25,642 $959 3 Round Culvert $23,670 $885 4 Bridge $13,640 $510 5 Bridge $11,426 $427
Municipal Case Study
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
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
Big storms will become increasingly likely 43% Extreme storms
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