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The Westmoreland Conservation District (WCD) didn't see the abandoned warehouse next door as an eyesore, but as an opportunity to expand its growing conservation campus. The district and its neighbors, the Ann Rudd Saxman Nature Park and Westmoreland County Public Works building, share a stretch of rural road in Greensburg, Pa.

They envisioned the 23,000-square-foot commercial building and surrounding grounds as a low-cost home for grassroots conservation, and agricultural and rural development organizations. The result: GreenForge, the first green rehabilitation of a commercial building in Westmoreland County.

Built in the mid-1980s, the original GreenForge building was a warehouse and office building with a sprawling paved loading dock, minimal parking, and no stormwater management. In 2004, the Westmoreland County Industrial Development Corporation bought the property to further its mission to support economic development, including redeveloping abandoned industrial sites. The district renovated the site to promote sustainability and create a visual appeal that would attract new tenants.

Weathering the storm

Concrete masonry products met the project's stormwater management needs while limiting impact to the site. Plans included retaining walls in the parking area outside the facility's front door to control erosion and water runoff. Their design also had to minimize earthwork disturbance, protect trees, and optimize native plant growth. The WCD chose a two-part solution: a traditional tiered wall to the north, and a sloping vegetated wall to the south.

The northern wall is an 8-foot-high vertical retaining wall made with Versa-Lok units. Typically, this type of wall would require excavation 8 feet back into the hillside, as far back as the wall is high. To protect the site's existing trees, the WCD used 12-foot-long Manta Ray anchors.

Crews excavated 2 feet into the slope and then drilled galvanized steel anchor rods horizontally into the subgrade beneath the root systems of the trees. The anchors were tied to the face of the wall with geogrid fabric. This technique saved 300 cubic yards of soil from being disturbed and protected a mature maple, oak, and dawn redwood tree.

The 8-foot-high retaining wall at the southern end of the parking area has a very different look. Sturdy, plantable Loffelstein interlocking retaining wall units were dry-laid on a 50-degree slope with standard backfill and subdrain. Each pocket was filled with soil and native plants. The gently sloping wall absorbs stormwater, promotes plant growth, and will eventually be covered with vegetation like a natural hillside.

Paving the parking areas at GreenForge posed a challenge. The existing parking area was insufficient for the new office space, but strict erosion control and stormwater management regulations meant less square footage could be paved. The WCD used several porous paving techniques for half of the new parking spaces, including pervious concrete, stabilized gravel, and permeable pavers.