Demonstrating
Innovation:
A Stormwater Retrofit at the Providence Supervisor's Office
Presented
at the Board of Supervisor's November 21, 2005 meeting
Members of the Demonstrating Innovation team
being recognized at the
Board of Supervisor's Presentation on November 21, 2005
Demonstrating
Innovation Presentation
(large pdf file 2 MB)
Demonstrating
Innovation Brochure
(pdf file 476 KB)
Demonstrating
Innovation: A Stormwater Retrofit is the recipient of the
2005 NACo Achievement Award
Ground
Breaking Ceremony for the Retention Rain Garden
June
21, 2005
Project
Update
Retention Rain Garden and Permeable Pavers
Slideshow
view of the project construction site.
Project
Updates
Focus
on Green Roof - Focus
on Retention Rain Garden - Focus
on Permeable Pavers
Focus on Permeable
Pavers
The Permeable
Pavers project is now completed. The project site is denoted
by "D" on the
Project/Scope Map.
Step
1. The project area was marked by Miss Utility to indicate
utility areas around the project site.
Step 2. The area was excavated to prep for both the
retention rain garden and the permeable pavers projects within
three days. Work was then halted for a few days due to two
rain storms that accumulated water in the project site that
became fondly refered to as 'the hole.' After the first storm,
water was able to drain but after the second storm, water
had to be 'pumped out' and allowed to 'dry out' before work
was resumed expediently.
Step 3. The area was then graded and had to be regraded
due to sediment deposit from the rain storms.
Step 4. Utility (light) poles were removed.
Step 5. Filter fabric was installed to prevent soil
and small particles from cloging water passage.
Step 6. Three feet of #3 stones were added as the next
layer.
Step 7. 28 Stormtech chambers were installed on top
of the stone layer. Each Stormtech chamer holds 45 cubic feet
of water - total project area will be able to retain 1260
cubic feet of water.
Step 8. Another layer of #3 stones were added to the
area.
Step 9. Concrete was then poured to create a curb that
separated the retention rain garden from the permeable pavers
parking area.
Step 10. The crew members then methodically and diligently
placed each pavers one at a time as the last layer of the
permeable pavers project.
Focus on Retention Rain
Garden
The Retention Rain Garden project is now completed. The project
site is denoted with "G" on the Project/Scope
Map.
The following work has been completed towards the retention
rain garden project:
Steps 1 - 9: See above.
Focus on Green Roof
The green roof project is now completed. The project site
is denoted with "E" on the Project/Scope
Map.
The following work has been completed towards the completion
of the green roof project:
Step 1. The concrete area of the roof top was
primed using a hot applied rubberized membrane known as MM6125
as manufactured by American Hydrotch.
Step 2. One ply of modified bitumen base was installed flushed
around the roof perimeter and down four spouts were installed.
Step 3. One layer of white cotton fabric and Hydroflex WSF
30 was next placed to protect the newly installed membrane.
Step 4. One layer of Hydroflex WSF 40 root barrier was loosely
laid.
Step 5. One layer of 1.5" 40 psi extruded polystyrene
insulation was installed.
Step 6. One layer of GR 15 drainage/water retention mat was
installed.
Step 7. One layer of filter fabric was installed.
Step 8. 4" of soil material was next placed on top of
the filter fabric.
Step 9. Placements of rock around the perimeter of the roof
was to prevent the down-spouts from being clogged.
Step 10. Lastly, seedum plants were planted for the completion
of the green roof.
Step
1: The concrete area of the roof top was primed using a hot
applied rubberized membrane known as MM6125 as manufactured
by American Hydrotch.
Step
2: One ply of modified bitumen base was installed flushed
around the roof perimeter and four down spouts were installed.
Step
3: One layer of white cotton fabric placed to protect the
newly installed membrane.
Step
3: One layer of Hydroflex WSF 30 being placed on top of cotton
fabric.
Steps
4 & 5: One layer of Hydroflex WSF 40 root barrier was
loosely laid.
One layer of 1.5" 40 psi extruded polystyrene insulation
was installed.
Step
6. One layer of GR 15 drainage/water retention mat was installed.
Step
7. One layer of filter fabric was installed.
Step
8. 4" of soil material was next placed on top of the
filter fabric.
Step
9. Placements of rock around the perimeter of the roof was
to prevent the down-spouts from being clogged.
Step
10. Lastly, seedum plants were planted for the completion of
the green roof.
More pictures of project construction
Installing
one of four passages for water flow from roof top.
Rubber
sealing around the water passage.
One
ply of modified bitumen base was installed flushed around
the roof perimeter -
controlling for water flow.
Sealing
the perimeter of the roof using Hydroflex WSF 30.
Pictures of materials used in project construction
Seedum plants.
Seedum plants.
back
to contents
Demonstrating
Innovation:
A
Stormwater
Retrofit at the Providence Supervisor's Office
General
Project Description
This LID
demonstration project is located within the Accotink Creek
watershed and has a drainage area of .83 acre. In addition
to the Providence Supervisor's Office, the site is also the
location of the County's Merrifield Fire Station #30. The
overall complex encompasses a land area of 1.8 acres with
approximately 1.44 acres being impervious. The proposed work
will serve as a highly visible demonstration project featuring
three LID practices: a bioretention basin (rain garden), a
green roof, and permeable pavers. The bioretention basin and
permeable pavers with infiltration trench will allow runoff
to drain into an underlying retention area where it can then
slowly infiltrate into the surrounding soil. The green roof
installation on an existing concrete storage structure will
serve to reduce rooftop stormwater runoff and provide a comparison
to an adjacent storage structure with an impervious roof.
The bioretention basin will occupy an area of 680 ft2 and
the permeable paver area is 1,550 ft2 in size, with a combined
volume of approximately 9,841 ft3 in the underlying infiltration
trench. The disturbed area will be 2300 ft2 in size. The green
roof will occupy an area of approximately 240 ft2. These three
integrated LID practices will work in harmony to address both
water quality and water quantity retrofit goals on the site.
They are expected to retain and infiltrate a significant amount
of the stormwater currently running off the impervious surface.
Read
our proposal
pdf
file (large)
A
conceptual diagram of the new rain garden and permeable pavers
area at Fire Station 30 - part of the recently-awarded DCR
Grant
to the Supervisor.
Related:
Environmental Excellence for Fairfax County
A 20-Year Vision
Related:
Low Impact Development: Controlling Runoff at its Source
Related:
DPWES LID document
(pdf
file)
Project
Scope/Map:
The
grant received funding from the Environmental Protection Agency's
Chesapeake Bay Program at the Virginia Department of Conservation
and Recreation.
