Yorktowne Square VA Stormwater Management Plan

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Yorktowne Square (VA) Stormwater Management
Plan 2905 Charing Cross Rd Falls Church,
VA Jeanette Stewart, Project Manager
2002-0169-005
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The perennial stream that receives Yorktownes
stormwater runoff
The Problem Because of development in the
surrounding areas, the stormwater drainage from
neighboring properties into Yorktowne has
increased. This increased volume of stormwater,
traveling through and under Yorktowne, carries
trash, sediment and other pollutants to a
perennial stream that flows into a regional pond
along Holmes Run, then into Cameron Run, the
Potomac and finally the Bay. This stream has
degraded rapidly and is characterized by undercut
and eroded banks, sediment laden water, and sand
bars. Trash is caught and collects along the
stream. Due to the lack of watershed management
and poor land management practices, Yorktowne has
contributed to these water quality problems, not
alleviated them.
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The Yorktowne Square Stormwater Management Plan
was developed to reduce the volume of and improve
the quality of stormwater draining from Yorktowne
property and neighboring areas thereby improving
the health of Cameron Run Watershed. The plan
included the implementation of restorative
landscaping techniques, BayScapes, over critical
acreage and creation of innovative stormwater
management designs as an engineered rain garden,
vegetative swales, vegetated drain areas, a green
roof typical of those used in heavily populated
Germany and polyprocessing cisterns to collect
rooftop runoff for data collection and water
storage for use in irrigation of an adjacent
BayScaped area. Our project was further
supported by a small watershed grant from DCR.
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Numerous organizations, public and private,
contributed expertise, materials, labor and
machinery. These are a few of our partners.
Northern Virginia Soil and Water Conservation
District
Fairfax County Dept. of Public Works and
Environmental Services
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Yorktownes Green Roof
We chose Building Logics green roof design
because of the structural limitations of our 35
year old building. The buildings dead load
capacity is 15 pounds per square foot. Building
Logics green roof system is light weight and met
our weight limitation. The system is a German
design. The architect and distributor in the USA
is Michael Perry, owner of Building Logics, and
is pictured on the far right. The other
gentlemen are the German manufactures of the
system. They visited Yorktowne in the summer of
2004.
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These seven layers make up the system. The soil
substrate contains less than 15 organic matter
and is made up of a light weight, highly
absorbent clay baked material. In order to meet
the requirements of the architect and structural
engineer, we replaced our ½ inch plywood deck
with a ¾ inch tongue and groove plywood deck.
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The Green Roof Construction May 2003
Our green roof required more steps than the usual
green roof installation. The original deck had
to be removed and replaced with thicker tongue
and groove material. Our actual construction
time was two and half weeks with the planting of
the sedums an additional two days. Normally the
construction time could have been accomplished
within a week to a week and a half.
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Growing medium
Spreading the growing medium
Transporting the material to the roof top
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Sedums arriving
Ready to go up
Up and partially planted

• The plants are of 3 varieties
• 2,800 Sedum Album
• 2,800 Sedum Sexangular
• 2,800 Sedum Reflexum
• A total of 8,400 sedums were planted on the roof.

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The sedums were planted within a 2 day period by
a crew of 3 people. Michael Furbishs company
Venture Management, Inc. installed the plants.
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The Green Roof July 2004 Within one year, the
vegetated cover more than doubled. We expect
complete coverage by summer of 2005.
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It is important to measure the effectiveness of
the green roof in reducing water runoff. Susanna
Tarney, (Masters degree candidate, Civil
Engineering, George Mason University) set up an
experiment using two 990 gallons cisterns to
collect the water draining from one of 8 drains
on the green roof and one of 8 drains on an
identical roof without vegetation. Two
submersible pressure transducers and data loggers
are being used to record the data. The
experiment is being conducted under the
supervision of the universitys engineering
department and Ms. Tarney will make the
information available when the experiment is
completed. In addition, the water runoff from
both roofs will be tested to measure any
filtering qualities the green roof may provide.
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Like many older properties, Yorktowne is
fortunate to have numerous mature trees. However,
there was little or no groundcover in these
areas. Such bare places promoted soil erosion
and little retention of water. We covered the
bare areas with mulch. These areas are being
planted with native or noninvasive plants. Bare
and compacted soil is also caused by foot
traffic. These areas were mulched and plants
were placed along the edges to encourage water
absorption.
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Examples of mulched and planted areas
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In order to reduce the flow of water from rooftop
drains or water into storm drains, we planted in
front of the drain area, even small ones.
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Turf grass especially along slopes does little to
slow down or retain water flow. Here, we covered
the grass with newspaper and mulch and planted
with native plants. This Virginia blue bell is
an example of a native that tolerates moist
conditions. This practice not only addresses
stormwater but also increases plant diversity and
reduces maintenance. It has been our policy not
to use fertilizers or pesticides on the property.
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These areas were once covered with turf grass.
The turf grass was replaced with native plants to
increase biodiversity and mulched to increase
water retention. Many of the plants were rescued
from development sites.
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Further examples of native plants in areas
previously covered with turf grass.
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We rescued rocks as well as plants. Below we
created a low rock wall along a slope to reduce
erosion. We filled the area behind the wall with
top soil before planting. Both rocks and flowers
came from an area to be developed.
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Yorktownes Engineered Rain Garden
Our rain garden was designed as a water quality
improvement facility. The size is based on
capturing the first 0.5 inch runoff from any
storm event. The total drainage area is 0.56
acre with impervious area (rooftops and parking
lot) making up .25 acre and lawns making up 0.31
acre. The dimensions are 20 x 30. The layers
are as follows mulch layer and ponding storage
on top, 1.0, biofilter soil, 1.5, pea gravel
layer, 0.5, gravel filter, 1.0. Total
excavation depth was 4.0. Dr. Asad Rouhi of the
Northern Virginia Soil and Water Conservation
District designed the garden. Dr. Judy Okay
assisted in survey work and construction
supervision. Fairfax County Department of Public
Works Environmental Services, Maintenance
Stormwater Management Division, provided
equipment and operators to excavate the area and
construct the garden.
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Materials were held in the parking lot awaiting
use
Gravel layer

Biofilter Soil being moved in after completion of
the pea gravel layer
Biofilter Soil
Observation well
Pea gravel layer
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Here, the crew from Fairfax Countys Stormwater
Management Division is preparing the under drain
system. An under drain system was necessary
because of the soil type of the area.

• Altogether, the county crew moved
• 5.5 Cubic Yards (CY) of Mulch,
• 34.0 CY Biofilter Planting Soil,
• 5.5 CY Pea Gravel,
• 22.2 CY of Filter Gravel (VDOT 57 stone).
• Construction was completed within a week.

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Water runoff enters at the forbay and is
captured in the garden but can leave the garden
once maximum capacity is reached either over the
spillway or through the under drain system. The
garden drains within 7 hours after the end of the
storm.
Forbay
Forbay
Outlet point for under drain
Berm and spillway
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After the garden was constructed. Dr. Okay
provided us with a list of Virginia native plants
to be installed. These plants are able to
tolerate both wet and dry conditions. Plant
selection included river birch, sweet bay
magnolia, arrowood viburmum, inkberry holly, tall
cone flower, Christmas fern, cardinal flower.
The end result was a functional and attractive
rain garden.
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The Dry Bed Stream, a Landscaping Feature to
Reduce Soil Erosion.
Once the garden was completed, we tackled the
problem of soil erosion along the path of the
water from the drain at the top of the slope to
the garden. This erosion had been a continuous
problem due to the large volume of runoff from
the parking lot and additions of runoff from the
rooftops as the water traveled down the slope.
Erosion along path of the water
Storm drain from parking lot
Storm drain from parking lot
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Soil erosion fabric was placed along the
established path of the water.
Eroded areas were covered with top soil to
prevent low spots in the bed.
The fabric was pinned with landscaping pins.
In all, over 4 tons of river rock were placed
in the dry bed stream.
4 river rock was placed over the fabric
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500 liriope were planted along the stream bed and
bare areas adjacent to the bed to further reduce
erosion.
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Education and Public Outreach Not only do we give
tours to the public but we have prepared a
booklet, Down the Drain, a Story About Urban
Water. and signage to help educate the public.
Down the Drain, a Story About Urban Water
covers many stormwater and watershed issues and
gives a detailed account of Yorktownes plan and
its implementation. It serves as an educational
piece as well as a guide for other individuals
and communities. We have included copies in our
report. This booklet is currently being prepared
for the web to enable interested parties to
download it directly. Three signs were prepared
to explain the project to the community and
visitors. They were placed either at the
location of the facility or at a central location
for information.
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Text for the General Information Sign
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Text for the Green Roof and Rain Garden Signs
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Yorktownes Project has served to demonstrate
LID and BayScape techniques to over 100
visitors within its first year. The project
manager, Jeanette Stewart, continues to give
tours of the project as well as presentations
to a widely diverse audience. The project has
received much publicity including coverage in the
Washington Post and other newspapers, as well as
articles in Fairfax County publications and
conservation newsletters. Television coverage
included Park Plus (local) and Blooming In The
Garden (regional Comcast program). The project
is featured in Dave Eckerts new film on Low
Impact Development, Reining In The Storm.
 
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ngarden.htm
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enroof.htm
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Tours have ranged in size from three to fifty.
This particular tour was sponsored by DCR shortly
after the green roof was completed. Presentations
have been and continue to be given to a wide
variety of organizations homeowner
associations, churches, garden clubs,
conservation groups. For example, we have been
part of the Providence District Environmental
Workshop and Green Roof Sustainability Technology
Lunch (over 100 people from the D.C. area
attended). We have been booked to give a
presentation as well as a tour for the Green
Roofs for Healthier Cities, an international
conference scheduled for May 2005 in Washington,
D.C.
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Dr. Rouhi using Yorktownes rain garden to teach
a conservation class
Project manager explaining the absorption process
of the green roof to a tour group
Group from Versars Cameron Run Watershed Tour,
our project was one of three sites visited.
Students from George Mason University - our tour
included the green roof and rain garden
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Carole Barth and Sharon Megs of Prince George
County have used our tours and materials since
our project began. They regularly book the tour
for their BayScaping, An Environmentally
Friendly Approach to Landscaping class (US Dept.
of Agriculture) and their From Rainbows to Rain
Gardens Growing One Million Rain Gardens for the
Bay, a rain garden workshop series,
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Hello Ms. Stewart and Yorktowne Square Board
Members   I want to congratulate you on the
impressive and innovative environmental projects
youve endorsed in your community. This past
Saturday, November 20th, Ms. Stewart gave a tour
to my USDA Graduate School class, including the
green roof, the rain garden, the wildlife habitat
and lots of Virginia native plants on your
property. We were impressed with the quality of
the work, the landscape value (even this late in
the season), and the dedication of residents of
the community to demonstrate what can be done to
help nature rather than just use it. You should
be incredibly proud of these projects and the
impact that theyve made to your property.   As a
personal note, after the tour, I have contacted
the head of the Buildings and Grounds Committee
in Fairlington Villages, a large condominium
community where I used to live. I gave her Ms.
Stewarts booklet about the Yorktowne projects,
and she was very intrigued. She plans to explore
some similar programs with her committee and the
Fairlington Board. So, youre providing a
wonderful model for the community at large,
too.   Again, congratulations on a very
impressive property and thank you for letting us
view it.   -- Kasha Helget 4102 Lester
Court, Alexandria, VA 22311 (703-820-8859)  
The tours have encouraged other communities to
take steps similar to Yorktownes. The
supervisor for Yorktowne's district, Linda Smyth,
was recently awarded a grant from Va. DCR to put
in a rain garden and green roof at her district
office. She will also demonstrate permeable
pavers with her project. Ms. Smyth has visited
our property several times and promotes our
communitys project at public events like
Fairfax Volunteer Fest.
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Yorktownes Green Roof has not only informed but
also dispelled many incorrect notions about green
roof technology. The fact that our roof is a
retrofit provides an additional benefit because
it demonstrates that this Low Impact Development
approach is not limited to new construction.
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We wish to thank our funders, partners and all
our volunteers for helping us make this project
successful. Yorktowne will continue to educate
and demonstrate to the public BMP and LID
techniques that promote the goals of The
Chesapeake Bay Program.