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2008 Featured Green Roof Project

National Audio Visual Conservation Center (NAVCC)

Location: Culpeper, Virginia
General Contractor: DPR Construction Inc.
Start Date: Fall 2004
Completion Date: Spring 2007
Size: 3 Million
Awards: 2007 Washington Contractor Merit Award
Featured Articles: Landscape Management Magazine - January 2007

Project Scope:
Installation of a nearly 6 acre extensive green roof system. The largest of its kind on the East Coast. The roof consisted of 7 different levels that received 4 different blends of custom soil mixes in depths ranging from 6" to 14'. What helped to make this roof unique were the range of slopes that were as severe as 26% on several portions. Since the roof had a weight restriction that limited OUI to using no equipment heavier than a plate compacter we were forced to use mulch blowing trucks to move the soils onto the roof. The specifications detailed moisture and compaction requirements for the installed soils which meant that every 4" lift had to be tested. That's 42 lifts in the areas receiving 14' of soil alone. Pulling plate compactors up a 26% slope with ropes in order to get the necessary compaction was a real challenge. The most sever slopes received an intricate drainage system under the stalite mix consisting of drainage mat run through 4", 6" and eventually 12" outfall pipes. The edge of the entire roof received an 18" wide gravel ballast vegetative free zone separated from the soil with 12"x9"x48" pieces of concrete curbing that weighed 400lbs. each. All of this had to be installed by hand. Once the soils and ballast were installed we got to planting the plugs. We planted 175,659 plugs at a rate of 5,000-10,000 a day depending on how many men were planting. We had at any one time up to 35 men working on the roof divided up among the various tasks. Lastly, the native topsoil areas were amended in place with Compro and seeded with the upland meadow perennial seed mix. The seed had to be sown in two phases raking some of the seed into the surface and broadcasting the rest. The surface was then stabilized with wood fiber tack from a hydro seeder for stabilization. The entire roof was the monitored and maintained for one year under contract. Maintenance for the first year was limited to watering as needed and weeding by hand. The seeding was mowed 4x a year to the smaller emerging plants to get established.

Soil Mixes:
Native Topsoil Amended w/Compro 8,690 tons
5/16" Stalite Fill 6,005 tons
Mix #1 4,014 tons
  55% Stalite
  30% Sand
  15% Compro
Mix #2 1,327 tons
  80% Stalite
  20% Compro

Succulent & Herbaceous Perennial Plug List:
15,065 Sedum album nurale 3.25" - 72 plug trays
3,545 Sedum betram Anderson 3.25" - 72 plug trays
15,065 Sedum kamtschaticum 3.25" - 72 plug trays
10,177 Sedum matrona 3.25" - 72 plug trays
15,065 Sedum reflexum 3.25" - 72 plug trays
15,065 Sedum sexangulare 3.25" - 72 plug trays
10,177 Sedum sieboldi 3.25" - 72 plug trays
15,065 Sedum spurium fuldaglut 3.25" - 72 plug trays
11,195 Achillea millefolium 3.25" - 72 plug trays
9,651 Allium schoenoprasum 3.25" - 72 plug trays
11,195 Anthemis tinctoria 3.25" - 72 plug trays
11,195 Carex flacca 3.25" - 72 plug trays
6,106 Dianthus deltoidea brilliant 3.25" - 72 plug trays
11,195 Festuca amethystina klose 3.25" - 72 plug trays
6,106 Seslaria autumnalis 3.25" - 72 plug trays
9,792 Talinum calycirum 3.25" - 72 plug trays

Upland Meadow Perennial Seed Mix:
6% Chamaecrista fasciculata Partridge Pea
5% Aster laevis Silk Smooth Aster
5% Echinacea purpurea Purple Coneflower
5% Rudbeckia hirta Black Eyed Susan
5% Senna hebecarpa Wild Senna
3% Heliopsis helianthoides Ox-Eye Sunflower
3% Senna marliandica Maryland Senna
2% Coreopsis tripteris Tall Coreopsis
2% Liatris spicata Spiked Gayfeather
2% Ratibida pinnata Greyheaded Coneflower
2% Rudbeckia triloba Brown-Eyed Susan
1% Aster sagittifolius Arrow Leaved Aster
1% Pycnanthemum incanum Hoary Mountain Mint
1% Ater novae-angliae New England Aster
1% Eupatorium hyssopifolium Hyssop Leaved Boneset
1% Solidago speciosa Showy Goldenrod
1% Monarda fistulosa Wild Bergamot
1% Veronia novaboracensis New York Ironweed
1% Tradescantia ohioensis Ohio Spierwort
1% Baptisia australis Wild Blue False Indigo
1% Penstemon digitalis White Beardtongue
15% Andropogon ternarius Splitbeard Bluestem
15% Sorghastrum nutans rusment Rusmey Indiangrass
10% Bouteloua curtipendula Sideoats Grams
10% Elymus canadensis Canada Wild Rye
Cover Crop Recommendation
5lbs/acre Lolium multiflorum Annual Ryegrass

Other Green Projects

Potomac Place
4th Street S.W.
Washington, D.C.
One story parking garage with intensive green roof. Soil was blown onto roof using mulch blowing trucks.
NIH Bay View
Johns Hopkins Bay view Campus
Baltimore, MD
Five story building with extensive green roof modules and extensive planters. Soil was installed using a crane. Project also included the installation of green screens.
Sinai Hospital Cancer Unit
Sinai Hospital
Baltimore, MD
Rooftop parking garage with extensive green roof.
Holy Trinity Church
O Street, S.W.
Washington, D.C.
Three story extensive green roof. Soil and equipment were placed on the roof with the use of a crane.
1209 North Charles Street
Baltimore, MD
Two story light weight soil mix creating an intensive green roof.
Aberdeen Proving Grounds
Aberdeen, MD
Three story intensive green roof
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