West Orange WEHI preliminary report

6 ç Landscaping Constitution Gardens In 1973, the U.S. National Park Service used a compost mixture made of digested sewage sludge, wood chips, leaf mold, and a small amount of topsoil to transform a badly compacted 40-acre tract of land located in Washington, DC, into a landscaped park. This project is one of the earliest successful large-scale landscaping appli- cations using compost. The original plans for the park renovations included planting azalea beds and thousands of annuals around a 6-acre lake. However, the site assessment revealed that the soil was almost as hard as concrete, with little pore space for plant roots and for water infiltration. The soil was too low in nutrients for healthy plant growth. In addi- tion, the water table was high, causing flooding and root rot in existing plants. Park Service staff spread over 9,400 cubic yards of the compost mixture over the site. Fertilizer, woodchips, and seed were added, and the soil was tilled to a depth of 2 feet. Impressed by the hardiness and beauty of a stand of hardwood trees along the area’s western edge, Park Service staff decided to plant several varieties of native trees rather than the planned azalea beds. Data taken 3 years after the project ended indicated that most of the nearly 2,000 trees initially planted had flourished in the park. The compost use in this project not only improved the quality of the existing soil, but also saved taxpayers over $200,000. Park Service staff also reviewed other options for remediating the soil at the park, including the purchase of topsoil to spread over the existing poor soil. If the Park Service staff had chosen to use topsoil, the cost of the project would have doubled. ç Using Compost for Rooftop Gardens Several years ago, officials at Pace School in Pittsburgh, Pennsylvania, proposed building a playground and garden for their students. They soon discovered, however, that the only space available was on the school’s roof, so they designed a unique rooftop garden. Plans for the garden included building large, 6-foot deep planters. Before the planters were constructed, several important factors had to be taken into consideration. The planter mix used had to be light enough for the roof to withstand the weight, yet dense enough to prevent rapid evapo- ration caused by the wind and summer heat. In addition, the planter mix had to be able to

mix used had to be light enough for the roof to withstand the weight, yet dense enough to prevent rapid evapo- ration caused by the wind and summer heat. In addition, the planter mix had to be able to endure freezing temperatures in winter, and provide ade- quate drainage to prevent the planters from over- flowing during rainstorms. Photo courtesy of U.S. National Park Service More than 9,400 cubic yards of compost was used to remediate heavily compacted soil at Constitution Gardens in Washington, DC. Photo courtesy of U.S. National Park Service Three years after compost was applied, the vegetation at Constitution Gardens flourishes.