Erosion Control Study Olmsted Woods
The Olmsted Woods provide a great history and an enchanting entrance to the Washington National Cathedral. The woods occupy 5 of the 57-acres of the Cathedral grounds and are the last vestige of an extensive oak and beech forest on Mount St. Alban, in Washington, DC. The forest includes foot paths, meditation spaces, native shrubs, wildflowers and an assortment of migratory birds.
Frederick Law Olmsted, Jr. provided the Master Plan in 1907 that has guided the development of the Cathedral grounds. His concept that the walk to the Cathedral should be filled with wonder and charm and the bustle of the city should be left behind. The All-Hallows Guild, the garden guild for the grounds, works closely with the horticultural team not only to beautify the grounds but to preserve the original vision.
Unfortunately, the area was plagued by flooding, erosion and run-off issues. Rutting, pooling and the loss of vegetation began to impact the lushness and beauty of the forest. Runoff washed out vegetation in the east ravine and under a walking bridge, walking paths became muddy and the banks of the stream channel were getting pushed further and further out.
In 1998 the All-Hallows Guild began a 3-million-dollar renovation. They needed to find a way to better control stormwater. After considering multiple options, the Guild worked with engineers and to install a product called Rainstore3 by Invisible Structures. Rainstore3 is a modular, stackable, underground water containment system which can be used for both subsurface detention basins and retention/harvesting systems. Invisible Structures is a Colorado based company has been a leader in the stormwater and erosion control industry since 1982.
The underground water storage tanks were selected for their ability to contain large amounts of water in a small area. Each unit of Rainstore3 measures 1 m x 1 m x 0.1m high (3.28 ft x 3.28 ft x 4 inches). The compression-fit units are stacked and sent preassembled to the construction site so there is no assembly required. A 94% void space equates to almost 25 gallons of water storage per unit with no gravel fill required. Large quantities of rainwater collection are easy to capture and store with Rainstore3.
By installing Rainstore3 in the Olmsted Forest the runoff from the stormwater could be captured and allowed to seep into the ground to prevent further erosion and promote the regrowth of the lost vegetation. The Guild captured the results over the years and bit by bit the integrity of the original landscaping returned. Vegetation returned in the Ravine and other low elevation areas, and the erosion issues were naturally corrected over time. Paths were clear of pooling and the riverbank was rebuilt as water levels running through became lower.
An additional interesting discovery made by the Guild is that many new species of plants began to appear or perhaps reappear in the forest. When the excess water was cleared, the vegetation was able to thrive. The All-Hallows Guild carefully considered renovation and their use of Rainstore3 proved successful. The Olmsted Forest once again became the beautiful, lush sanctuary that Frederick Law Olmsted, Jr had envisioned.
Invisible Structures is the leader in porous paving and stormwater management solutions. We provide the finest in grass porous paving, gravel porous paving, underground stormwater storage, erosion control, drainage, and access mats.
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