New 90-Mile-Long Storm Water Drain Helps Kentucky Road to Become Federal Interstate

When the William H. Natcher Parkway became I-165, more was needed than just widening the road - a completely new edge drain that ran for nearly 90 miles was required to control storm water runoff and meet federal highway requirements. Converting the Natcher Parkway into an I-65 spur was undertaken as a way to improve economic development opportunities for the region. The improvements and upgrades will meet the federal guidelines for interstate standards by extending the ramp tapers making it safer for drivers to exit on and off the interstate as well as upgrading the bridge walls and bridge decks. It is part of Kentucky’s 2018 to 2024 Highway Plan that includes $8.5 billion for more than 1,400 projects, such as bridge and pavement improvements, road widening, reconstruction of existing roads, and new routes and interchanges.

The total amount of drainage pipe used was more than 472,000 feet of Advanced Drainage Systems, Inc. (ADS) (NYSE:WMS) four-inch diameter, perforated single wall N-12® corrugated high-density polyethylene (HDPE) pipe and the same amount of ADS 0701T six-foot wide geosynthetic fabric. The $28 million road project which ranged from Bowling Green to Owensboro, was accomplished by contractor Westate Construction of Hopkinsville, KY. Because the pipe came in 3,200-foot coils, plus the fabric was also easy to install in the trench and wrap around the pipe, the job was completed on time. It was typical for the Westate crew to install 9,000 to 12,000 feet of pipe and fabric in a day.

The trench is lined with ADS Geosynthetics 7.0 oz (0701T), a needle-punched nonwoven geotextile made of 100 percent polypropylene staple fibers, which are formed into a random network for dimensional stability. It resists ultraviolet deterioration, rotting, biological degradation, naturally encountered basics and acids. Polypropylene is stable within a pH range of 2 to 13. ADS N-12 HDPE perforated pipe is then laid in the trench. It is approved for use by many state and federal agencies. Named for its excellent Manning’s “n” rating of 0.012, the N-12 pipe was designed in 1987 by ADS specifically for culverts, storm sewers, highways, airports and other civil design construction. The ADS pipe is available in diameters from four to 60 inches.

For years, highway base drainage methods have included free draining bases, french drains, pipe and aggregate subdrains and geo-composite edge drains. The growing importance of drainage has been driven by the design of the Interstate highway system with dense, relatively impervious base-course materials and limited underdrain design. The trapping of water between the pavement and base has led to drastically shortened highway life. The basic design of the drainage system is intended to improve the rate of the introduction of free water by increasing the surface area in contact with the base-course material and by placing the product in intimate contact with the pavement edge and the base-pavement interface.