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Project Name: Legion Park

Project Location: Blair County, PA

The Problem

In the Fall of 2004, Legion Park representatives approached the Blair County Conservation District with a problem.  The Legion Park parking lot, near the sports fields and pavilions, often had a problem with water ponding after rain events. This created problems for parking long after rain events were over. Historically, stone was periodically placed on the Legion parking lot to aid in creating a better parking surface. This solution proved to be only a temporary fix for a much larger problem. The parking lot was a low spot in the park. The ponding water on the parking lot had nowhere to drain. Years of parking traffic had compacted the underlying soils and stone to an extent that would allow for minimal infiltration of water back into the ground. With no place to drain and very little infiltration, the water would remain on the parking lot for an extended period of time.

The Solution

The Blair County Conservation District recognized this problem and suggested that a product called GEOWEB® might be the solution. GEOWEB is a plastic three-dimensional cellular confinement system that is manufactured by Presto Products Company. The GEOWEB system has many applications including: load support for parking surfaces, slope protection, channel protection, and earth retention. The product comes in many different sizes and the size requirements depend on desired use and needs. Recognizing that compaction and lack of drainage were the primary factors at Legion Park, the Conservation District felt that the stormwater storage and load support abilities of the GEOWEB would be a suitable solution to the problems.

Design Considerations

The Conservation District approached Keller Engineers, Inc. to help with a parking lot design that would minimize the parking lot problems. The design team then contacted ACF Environmental, the local Pennsylvania supplier of the GEOWEB product. ACF Environmental suggested that the 4-inch depth GEOWEB cell could be used. To allow for stormwater storage and infiltration, the design team decided that excavating the existing compacted soil and stone from the parking lot was necessary. A trench approximately 180 feet in length, 2 feet deep, and 11 feet wide was also included in the design to allow for additional stormwater storage. The design also called for geotextile separation fabric to be used between the underlying soils and the parking lot materials. The design team contacted local contractors Ben L. May Excavating and Richard Curry Excavating to aid in final design and project layout. Ben L. May Excavating made the final touches on the design, aided in layout, and was essential in the completion of the project.

Constructing the Permeable Parking Lot

On June 2, 2005 the first phase of the project began. Hollidaysburg Borough excavated the top few inches of existing parking surface materials—mainly stone gravel. This material was placed on other roadways throughout Legion Park.

The second phase of the project began on June 6th with Ben L. May Excavating removing the remainder of the existing compacted materials and Richard Curry Excavating hauling the materials from the site. The trench was also constructed at this time. By late afternoon the project was ready for the geotextile separation fabric to be placed. Representatives from the Blair County Conservation District , ACF Environmental, and Keller Engineers placed the fabric on the freshly excavated surface and in the trench.

That same evening, New Enterprise Stone & Lime Company brought the first layer of clean #3 stone. The stone was placed over the entire parking surface and in the bottom half of the trench. The voids in the #3 stone would allow for stormwater storage under the parking surface. Once the #3 stone was placed to the desired depth, a thin layer of #57 stone was placed on top of the parking lot. Another layer of geotextile separation fabric was placed in the trench and the remainder of the trench was filled with topsoil.

In early June, volunteers from the Blair County Conservation District, Keller Engineers, Unitarian Universalist Fellowship of Blair County, ACF Environmental, and Natural Resources Conservation Service began placement of the GEOWEB material. This type of project had never been completed in Blair County and the GEOWEB placement was a learning experience for all of the volunteers. As large sections of the GEOWEB was placed, it was then backfilled by Ben L. May Excavating and Tom Hurliman with more clean #57 stone. Two weeks later, the Conservation District completed permanent seeding and mulching of disturbed areas around the parking lot and temporary seeding and mulching of the trench/landscape area. The final landscape plan for the trench area was completed in the Fall. A sign describing the parking lot and identifying volunteers and contributors was erected in the landscaped area.

Project Performance

The final product was a success. The total improved parking area measured approximately 16,300 square feet.  Although rain events during the summer of installation were rare, a few heavy thundershowers proved that the stormwater storage capacity of the parking lot and trench were more than enough to handle significant sized storms. The load support capabilities of the GEOWEB structure will support the weight of the vehicles and will greatly reduce the compaction of the underlying stone and soils.

This project could not have been a success without the help of the many volunteers who contributed time, materials, equipment, money, and labor to this worthy project. Without these volunteers and their contributions, this project would have never been completed.