March 30, 2016

Evan Goldman
EYA
4800 Hampden Lane
Suite 300
Bethesda, MD 20817

RE: 12th and Allison Development

Dear Mr. Goldman,

Casey Trees is a Washington DC-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 elected 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. As a city, we will
achieve this goal when development projects protect existing trees and plant new trees, and when the District
adopts policies that grow the city’s urban forest. Therefore, we are excited to provide you with comments on
the 12th and Allison development project on the property surrounding the St. Joseph’s Seminary building.

Throughout the community engagement process for the 12th and Allison project, the EYA development team
openly engaged in discussions with Michigan Park neighborhood residents and organizations. After presenting
the initial concept plan, EYA sought community feedback, and ultimately incorporated this feedback into a new
design with fewer proposed townhome units, additional public green spaces, and a plan to protect a majority
of the mature trees on site.

The current plans for the 12th and Allison project show existing trees protected and new trees planted along
internal streets. To ensure these trees are able to live long lives and grow large canopies, we recommend the
following best practices:

1. Work with Casey Trees to preserve green space in a conservation easement: Setting aside the green
space around St. Joseph’s Seminary in a conservation easement would allow neighbors access to these
parks in perpetuity, and would give trees a permanent space to grow. Casey Trees is available to serve
as a conservation easement holder for this property.

2. Prioritize shade trees: When selecting the new street trees for this project, choose appropriate species
based on available sunlight and rooting space to grow a healthy tree canopy. Where possible, prioritize
large canopy shade trees to maximize benefits. Consider working with Casey Tees to establish a
planting plan. Casey Trees’ Urban Tree Selection Guide is available for guidance.

3. Use advanced tree growth systems to maximize soil volume: Project renderings show trees lining the
development’s interior streets. To allow these trees to thrive and provide maximum canopy benefits,
install soil cells or structural soils under new sidewalks. These systems provide adequate soil volume
for roots, allow soil to remain un-compacted, and facilitate tree root growth.

4. Include trees in any bioretention areas: Based on current plans, about half of the 12th and Allison
property will transition from green space to homes and streets. Any bioretention areas designed to
manage the additional stormwater runoff from these impervious surfaces 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.

5. Require a maintenance plan: Newly planted trees are vulnerable as their root systems have not yet
expanded far enough to gather water from a large area. It is crucial that trees less than 3 years old
receive 25 gallons of water or 1.5 inches of rainfall per week to survive. Employing regularly scheduled
maintenance and tree health monitoring will ensure establishment and survival of young trees,
reducing the need for costly maintenance in the future. Therefore, we recommend working with the
homeowners association to develop a long-term maintenance plan for the 94 new trees.

6. Protect existing trees during construction: Adding tree protection fencing around any existing trees on
or near the construction site will prevent damage from equipment and debris. We recommend
installing metal fencing beyond the critical root zone of these trees, as well as clear signage, as
specified in the District Department of Transportation’s tree protection requirements (DWG NO.
608.10).

EYA’s responsiveness and inclusion of sustainable design elements in the 12th and Allison project demonstrates
the many advantages of collaborating with the surrounding community early in the development process. We
look forward to seeing this tree-filled site provide numerous benefits to the Michigan Park neighborhood for
years to come.

Sincerely,
Kristin D. Taddei
Planning Advocate
Casey Trees

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