Huntington, W.Va., applies low impact development practices to new Taco Bell location
The Ohio River stretches from Pittsburgh to its confluence with the Mississippi River at Cairo, Ill., a distance of 891 miles. It drains more than 12 million acres of land in parts of 15 states and forms a border for six states. Hydrologically, it is the main stream of the entire U.S. river system. Huntington, W.Va., relies on and benefits from its position on the river. It is a city of about 50,000 people, located approximately 300 miles west of Pittsburgh. It is a major hub for industry and transportation, and can boast being the second largest inland port in the U.S.
When the 1936 flood (called the "super flood") crested, it flooded the second stories of downtown businesses in Huntington and many river cities, causing Congress to authorize and fund flood control works. Since then, the Army Corps of Engineers has constructed hundreds of miles of levees, flood walls and channel improvements along with 375 major reservoirs, including those reducing the flood threat for the cities along the river and its major tributaries.
Huntington currently is facing several water issues, including street flooding, combined sewer overflows (CSO), and the water quality of the river. As a first effort to simultaneously combat the problems, Huntington has taken steps to assure that all new development include provisions to assure that no additional runoff enter any part of its storm drainage system. Eastham & Associates of Chesapeake, Ohio, was selected to provide the surveying and civil engineering for a new Taco Bell restaurant-a project by M.C. Development Co. of Louisa, Ky. As a part of the assignment, Eastham & Associates completed the analysis, designs and permit for the storm water management facility.
This project provides the restaurant building with a new style design, a drive-through window, a parking lot, a picnic shelter, a storage and dumpster area, two entry driveways from Kinetic Drive, three storm water bio-retention cells, and a variety of other amenities.
The site is a ½-acre tract at the entrance to Kinetic Park, an industrial park adjacent to a major highway in the outskirts of Huntington. The site fronts on Kinetic Drive (WV State Road 10/20), the park’s main drive, and is across the drive from Fourpole Creek, an Ohio River tributary. It has a slight slope, but generally is flat and now is vacant. The only encumbrance is an emergency generator on adjacent land belonging to the Huntington Sanitary Board, which must have access for heavy trucks and machinery through Taco Bell’s site.
Eastham & Associates' assignment was to provide all surveying, site design (exterior to the restaurant building), all utilities and their connections, construction plans, and specifications and permit applications. The team furnished architectural plans for the building, a traffic study, basic site layout, a geotechnical report, the exterior lighting and sign locations, Taco Bell’s specifications for the drive-through features, as well as a best management practices (BMP) plan to assure construction-generated sediment and debris did not exit the site or reach any stream.
The city planners are working to add to their existing Paul Ambrose Trail for Health trail system, and a loop around Kinetic Park and Taco Bell has been suggested. The initial sections of the trail, some of which are atop the Huntington Floodwall levee, connect with Ritter Park and Harris Riverfront Park, major parks in Huntington. They also provide bicycle lanes painted on many streets.
After completing the boundary and topographic surveying, the Grading Plan was developed to provide the earthwork needed to assure compliance with the American Disabilities Act, while establishing the building’s Finish Floor Elevation, the Parking Spaces’ locations and dimensions, and the future needs to manage storm water runoff to meet Huntington’s ordinances.
Handling storm water issues quickly became a primary focus. To simultaneously address the challenges facing Huntington requires making two separate calculations to determine the quantity of runoff to be managed. The first calculation is to determine the post-construction storm water runoff from a 1-in. storm. The WV Department of Enfironmental Protection (WVDEP) Manual uses a 1-in. storm to achieve an acceptable level of water quality benefits, primarily the reduction of total suspended solids and key chemical contaminants. Since natural storms frequently exceed 1 in. of runoff, the second calculation determines how much total additional runoff is created by the development. This requires comparison of pre-construction and post-construction runoff.
Calculations to determine all runoff for Taco Bell are based on the “rational formula”-a formula developed from empirical data around 1889, which provides a simple calculation for determining peak runoff at a selected point for small drainage basins of less than 200 acres. Experience led Eastham & Associates to the conclusion that managing Taco Bell storm water to meet the requirements could best be accomplished using bio-cells and determining the total storage requirements for a storm event with a 1% chance of annual occurrence based on a statistical analysis of historical events, often dubbed a 100-year storm.
Performing the first set of calculations using the spreadsheet for a 1-in. storm would require 1,504 cu ft of storage. Performing the second set of calculations yielded the finding that all post-construction runoff from a 1% storm would require a total of 2,016 cu ft of storage. Cells must be sized to hold water until that water percolates into the soil. This is determined by a geotechnical conclusion of the soil type and its normal percolation rate, where the heavy clay at Taco Bell percolated 0.30 in. per hour. Thus the cell(s) should be designed to store the 1-in. criteria, then be expanded to meet the total additional runoff established by the rational formula, all with a comfortable safety factor in recognition of the, as yet, indefinable allowances for climate change and resiliency.
The bio-cell design requires a shallow pond on top to hold 50% of the capacity needed for the cell if the trial pond depth is chosen to be less than 1 ft. If the depth is 1 ft or more, its capacity must be 70%. This pond serves to temporally hold the runoff should more than one storm arrive before the collected water can be percolated. It also must drain fast enough to prevent creating a vector (mosquito) problem. Water seeking plants (flowers, shrubs or small trees) will be planted in the pond, which most often is wider than the trench and is below the pond. This trench must hold the entire required storage capacity as calculated for the 1-in. storm event plus the additional capacity from the 1% (100-year) storm. It is back-filled with a specified depth of soil media consisting of a mixture of sand, top soil and mulch or river rock to clean the water of contaminants and promote percolation into the soil.
To accommodate handling runoff from storms larger than 1-in., additional storage is added by an aggregate-filled reservoir below the soil media. A thin bed-usually 3-in. thick-of small aggregate such as river rock serves as a choker stone between the media and reservoir. Below all this, the natural soil is scarified to a depth of approximately 12-in. to assist percolation.
Due to the final grading needed to meet Taco Bell’s restaurant requirements and the limited available area for bio-cell construction, it was not possible to handle all storage requirements in a single cell, and three different cells were used instead. Cell #1 was located west of the restaurant building to manage the runoff from its roof and a small drainage area on nearby land. It is rectangular in shape, 18-ft wide and 40-ft long, and it provides treatment for 1,273 cu ft of runoff. It also has a 6-in. pipe underdrain to drain any excess from a much larger storm event that cannot be controlled in the cell. The underdrain pipe directs water to an existing detention pond provided in the original Kinetic Park development from where it eventually is released to Fourpole Creek so that no new water enters the city storm drainage system.
The other two cells are placed in the Kinetic Drive right-of-way with permission through a West Virginia Division of Highways Right-of-way Encroachment Permit. These cells collect runoff from the parking lot and an adjacent drainage area. They could have been considered a single cell, but had to be separated to avoid damages to an existing sanitary sewer manhole. They are shaped to match the right-of-way boundary, with a combined surface area of 654 sq ft, and together provide storage and treatment for 1,060 cu ft. They are sized to treat a 100-year storm. An underdrain is provided should there be any minor overflow due to intense storms. It would flow into Kinetic Drive’s storm drains, which discharge into Fourpole Creek. This arrangement as designed will handle a total storage of 2,333 cu ft.
A Work in Progress
The final appearance of each of these cells will be an appealing flower garden. Careful construction along with minimal maintenance of the cells and their respective drainage areas will be required to provide and preserve their integrity. Huntington approved the plan and issued a Stormwater Management Plan Permit Sept. 17, 2018. Using this combination of products and procedures for the Taco Bell project permitted the entire site to incorporate low impact development practices, free of the need for major site obstructions or revisions and leaving the completed site well appointed while meeting all of Huntington’s goals and objectives, plus recognizing the potential for increased needs due the climate change and resiliency considerations. Construction was initiated in September 2018 and is nearing completion.