September 30, 2016

Stacee Hemby
Outreach Coordinator
Tina Boyd & Associates

Re: Cleveland Park Streetscape & Drainage Improvement Project

Dear Stacee Hemby,

Casey Trees is a Washington, D.C.-based nonprofit, with a mission “to restore, enhance, and protect the tree canopy of the Nation’s capital.” To fulfill this mission, we plant trees; monitor the city’s tree canopy; and work with government officials, developers, and residents to prioritize the District’s trees and to encourage tree planting on both public and private property. We are dedicated to helping the District reach its 40 percent tree canopy goal by 2032 – an achievable goal only if the District actively grows the city’s urban forest. Therefore, we are excited to provide you with comments on the Cleveland Park Streetscape & Drainage Improvement Project.

In 2013, the District Department of Transportation (DDOT) released a report detailing the findings of their transportation study on the stretch of Connecticut Avenue NW between Porter Street and Macomb Street. The Cleveland Park Transportation Study Final Report (the report) affirmed the importance of this three block stretch as a destination for residents and visitors and an essential corridor for commuters. In addition, this strip is nestled between some of DC’s most loved green spaces: Melvin C. Hazen Park, Rock Creek Park, and Smithsonian National Zoological Park. The Cleveland Park Streetscape & Drainage Improvement Project provides an opportunity to expand tree canopy along Connecticut Avenue and connect these vital swaths of habitat.

The report also outlined existing conditions, challenges, and recommendations for improving this section of Connecticut Avenue. The most prominent needs identified in the study include more gathering spaces, a safer environment for pedestrians, green infrastructure to manage stormwater, and larger growing spaces for street trees. In order to achieve these outcomes and work toward the District’s environmental goals, we suggest incorporating the following recommendations into the plan to improve Cleveland Park’s streetscape and drainage.

Adopt Service Lane Possibilities 3 or 4 as Presented in the Report

The report presented four possibilities for improving the sidewalk along the east side of Connecticut Avenue (page 39). Currently, a narrow sidewalk and service lane exist on this side of the street, which is inconsistent with the historic wide sidewalk on the west side of Connecticut Avenue. According to the report, trees on the east side of the street “exhibit signs of stress including limited growth and poor canopies,” and “are not as healthy as they could be if they had larger and better root zones and more permeable surfaces (pages 23, 35).” We recommend adopting possibilities 3 or 4 to expand the sidewalk on the east side of Connecticut Avenue. This additional space will allow DDOT to expand growing spaces for street trees.

Improve Soil Space for Trees

Wide sidewalks allow for continuous planting strips instead of tree boxes. We recommend transitioning to planting strips along Connecticut Avenue. This design method provides the additional space necessary plant more trees. Casey Trees supports the report’s recommendation to expand the number of street trees along Connecticut Avenue from 43 trees to 56 trees (page 54). When selecting new trees for Connecticut Avenue, prioritize large shade trees when possible.

In addition, consider installing soil cells or structural soils under sidewalks. These systems facilitate tree root growth and provide adequate soil volume for roots, allowing soil to remain un-compacted.

Pedestrian safety along the Connecticut Avenue corridor has been identified as a key issue by both the community and D.C. Council. When trees are given ample soil space through the use of planting strips, soil cells, or structural soils, they are able to grow large canopies that overhang sidewalks and streets. Streets lined with large shade trees have a traffic calming effect, which keeps drivers and pedestrians safe.

Include Trees in Bioretention Areas

Streetside bioretention was suggested in 2013 and 2016 as a solution for managing the excess stormwater runoff common in Cleveland Park. Stormwater runoff typically gathers along the west side of Connecticut Avenue and in front of the eastern metro station entrance. All bioretention areas installed to absorb excess stormwater should include trees. Trees in bioretention areas further slow stormwater runoff and reduce pollution through interception, evapotranspiration, and nutrient removal. Casey Trees’ Urban Tree Selection Guide may be consulted to select trees that perform best in bioretention areas.

Protect Existing Trees

During construction, ensure that all street trees scheduled to remain are adequately protected. Adding tree protection fencing will prevent damage from equipment and debris. Install clear signage and metal fencing beyond the critical root zone of any trees on or near construction sites, as specified in the District Department of Transportation’s tree protection requirements (DWG NO. 608.10).

Thank you for the opportunity to comment. Casey Trees would be happy to work with you to provide tree-related analyses for the Cleveland Park Streetscape & Drainage Improvement Project. If you have any questions about these recommendations, please feel free to contact me at ktaddei@caseytrees.org.

Sincerely,
Kristin Taddei

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