Most culverts used by highway departments are made of steel, which over the years wears or rusts out. Traditionally, to replace a worn out culvert, it is dug up, removed and a new steel culvert put in its place. This process is costly, labor intensive and disrupts traffic flows.
Dyer Sales, located in Esperance, NY, offers a Department of Transportation (DOT)-approved alternative for culvert repair instead of replacement — using polyethylene liners.
Delaware County Department of Public Works (DPW) uses pipe liners where it can to save money, time and interruption to the traveling public. The department has used liners in a variety of shapes and sizes for many years. Mostly, they have been used to repair culverts that are failing but not to the point of complete collapse or even to the point that they are extremely distorted in shape.
Located in the Catskill Mountains, Delaware County, NY, is approximately 1,470 sq. mi. in size and has a population of approximately 47,500 people. The DPW has 270 mi. of road and since it owns all the bridges in the county that are not owned by New York State Department of Transportation (NYSDOT), it has 273 bridges.
“Our data base indicates that we have over 101,000 ft. of culvert pipe on the system, therefore culverts are a very expensive item for us. Most of our pipes are corrugated metal pipes that have served their useful life. They are on quite steep slopes and our water is very acidic so the inverts have rusted out. We have attempted many different methods to repair the culverts in a cost effective and efficient way, including using smooth bore steel pipes to line the original, construct a concrete invert in larger pipes that allow practical human access, and lining the smaller ones with any number of plastic liner products,” said Wayne Reynolds, Commissioner of Public Works, Delhi, NY.
“Many of our culverts are in deeper fills, ranging in depth from 5 to 30 feet. To replace a deep culvert while maintaining traffic can be very costly and time consuming, not to mention aggravating to the traveling public. We have had some pipes that did fail completely and had to be replaced conventionally. The earthwork involved in taking the traffic down reasonable grades with you as you excavate to the pipe is immense.
“Obviously, the longer the section of road you have to tear up to get reasonable grades means the more subbase, and paving that has to be replaced. A single pipe replacement can take up to three weeks and cost tens of thousands of dollars. We try to avoid those at all costs,” Reynolds added.
“Liners are not for every pipe. There are a number of design considerations that must be addressed before you proceed. However, our initial calculations indicate that we can install a liner in a 4 foot deep 24-inch pipe for about 90 percent of a conventional replacement cost and in about 66 percent of the time. In today’s budgetary times when manpower and funds are short that gives us a tremendous edge. For deeper pipes the cost is substantially greater.”
Lining pipes is not weather dependent and it is better for water quality because there is less disturbance during construction.
There also are fewer disturbances to the traveling public.
“You can perform all the work while maintaining at least one lane of traffic and if you have a wide shoulder you can do all the work while maintaining two-way traffic. In addition, you do not get the differential settlement after the work is completed. That settlement can be a source of many aggravated motorists and many costly return trips for patching. Not to mention the shock to your snowplows,” Reynolds said.
Polyethylene, which is placed inside the existing culvert, comes in sections and snaps together. The pipe that goes inside the existing culvert will be somewhat smaller than the existing pipe, but the new pipe has a smooth wall, unlike the corrugated pipe that it is going inside of. The smooth wall allows water flows equal to or greater than the original culvert pipe that it is replacing.
Dyer Sales provides the product, guidance and expertise for the culvert replacement, but the highway departments generally do the installation themselves. After a culvert is repaired with the polyethylene replacement it should have a life expectancy of up to 50 years.
For more information, call 518/875-6161 or visit www.isco-pipe.com. P