FINAL DESIGN PRESENTATION N Larrimore St and 9th St N(Dominion Hills Neighborhood)

Naudy Martinez, Neighborhood Conservation PlannerCommunity Planning, Housing, & Development

Neighborhood Conservation Program

Agenda:

1. Overview of the presentation and project Naudy Martinez, NC Planner

2. Presentation of the Street Improvement Design PlanGino Squarciafico, Design and Engineering Supervisor

3. Presentation of Landscape PlanJill Yutan, NC Landscape Architect

Agenda cont’d:

4. Presentation of Rain Garden Landscape PlanAnne Guillette, Watershed Projects Manager

5. Review of Temporary Easements and Next StepsNaudy Martinez, NC Planner

Presentation purpose: Review of final design for street improvement and rain garden at the intersection of N Larrimore St and 9 St N.

Project goal:Change the design of the intersection to improve pedestrian safety and as applicable, include other beautification elements including plantings and improvements to existing conditions.

Project timeline:Project submitted: November 2013General Interest Survey: November 2015Concept Design meeting: March 2019Project qualified: May 2019, 95% approvalRec for funding: June 2019Project funding approved: November 2019

View from the SE corner of 9th St N and N Larrimore St

Aerial view of 9th St N and N Larrimore intersection

Presentation of the Street Improvement Design PlanGino Squarciafico, Design and Engineering Supervisor

Presentation of Landscape PlanJill Yutan, NC Landscape Architect

Presentation of Rain Garden Landscape PlanAnne Guillette, Watershed Projects Manager

N Larrimore Street Rain Garden

• Arlington County has Stormwater Permit from the Virginia Department of Environmental Quality (DEQ) which mandates activities to protect water quality

• This is achieved by reducing stormwater pollution(runoff)

• In 2010, a new “pollution diet” was adopted for the Chesapeake Bay – the Chesapeake Bay Total Maximum Daily Load (TMDL)

• Rain Gardens are one way that Arlington is using to meet pollution reduction goals

Arlington County’s Regulatory Requirements

• In 2014, County updated Stormwater Master Plan

• The Plan included a study of all County-owned property to find potential locations for new stormwater facilities

• Over 1200 potential sites were identified

Stormwater Master Plan

County-Wide Stormwater Assessment

Stormwater Assessment –Four Mile Run (Upper Mainstem) Watershed

Potential Retrofits

When polluted stormwater enters storm drains it is conveyed without any treatment to the nearest waterway, and this is harmful to the stream as well as its habitat. Four Mile Run is the stream which receives the runoff in your neighborhood. The proposed Rain Garden will filter the runoff through the soil media and plant material and subsequently reduce the amount of nitrogen, phosphorus and sediment entering Four Mile Run, the Potomac River and ultimately the Chesapeake Bay. Residents can be proud that the Rain Garden in their neighborhood improves the water quality and the habitat of Four Mile Run.

How Rain Gardens Help

the Potomac River

Overflow

Stormwater runs along the curb and enters the Rain Garden via a “trench” which flows under the sidewalk

Decorative Trench Cover

If water rises to the level of the riser it enters the pipe and is directed to the storm system

Riser in rain garden

How the Larrimore Rain Garden Works

Design Parameters• Provide 3’ mowing strip at base of hill• Locate plants to restrict short-cutting behind rain garden• More symmetric design• Feedback on trees, shrubs, perennials & groundcovers

Meetings with Residents• December 2, 2019 (60% Design)• January 29, 2020

Restrict passage

Draft Design

Resident Meetings & Design Parameters

Rain Garden Planting Plan

How to Read the Plant List

Curb Cut Inflows

Overflow

• Plants are selected according to their ability to thrive in different water levels, whether they are on the upper ‘edge’ or slope or in the deeper part of the ‘basin’

For example, Blue Flag Iris (Iris versicolor) can tolerate “wet feet” where their roots are able to tolerate standing water for days and days, so they are located in the basin

• Plants are also selected based on their micro-climate, seasonal value, habitat value (i.e.., butterfly host plant), height, form/ structure, bloom time, bloom color, leaf texture & color, etc.

• Contractor will perform maintenance once per month from March to November

Rain Garden - Native Plants

• Serviceberry (AA)(Amelanchier arborea)

• Sweetbay Magnolia (MV)(Magnolia virginiana)

NOTE: Photos are for presentation purposes only and should not be reproduced as they are not owned by Arlington County.

Trees

NOTE: Photos are for presentation purposes only and should not be reproduced as they are not owned by Arlington County.

Sweetbay Magnolia

Tiger Swallowtail Butterfly

Shrubs

• Buttonbush (CO)(Cephalanthus occidentalis‘Sugar Shack’)

• Panicle Hydrangea (PHL)(Hydrangea paniculate ‘Little Lime’)

NOTE: Photos are for presentation purposes only and should not be reproduced as they are not owned by Arlington County.

Shrubs

• Winterberry (IVE)(Ilex verticillata – Male + Female)

• Yaupon Holly (IVO)(Ilex vomitoria – Male + Female)

NOTE: Photos are for presentation purposes only and should not be reproduced as they are not owned by Arlington County.

Shrubs

• Dwarf Yaupon Holly (IVN)(Ilex vomitoria ‘Nana’ – Female)

• Virginia Sweetspire (IVI)(Itea virginica ‘Little Henry’)

NOTE: Photos are for presentation purposes only and should not be reproduced as they are not owned by Arlington County.

Perennials, Sedges & Grasses

NOTE: Photos are for presentation purposes only and should not be reproduced as they are not owned by Arlington County.

• Eastern Bluestar (AT)(Amsonia tabernaemontana)

• Swamp Milkweed (AI)(Asclepias incarnata)

• New York Aster (ANA)(Aster novae-angliae)

• Creek Sedge (CA)(Carex amphobia)

Perennials, Sedges & Grasses

NOTE: Photos are for presentation purposes only and should not be reproduced as they are not owned by Arlington County.

• Pink Turtlehead (CHL)(Chelone lyonia)

• Tickseed Coreopsis (CZ)(Coreopsis verticillata)

• Hardy Hibiscus (HM)(Hibiscus moscheutos)

• Blue Flag Iris (IV)(Iris versicolor)

Perennials, Sedges & Grasses

NOTE: Photos are for presentation purposes only and should not be reproduced as they are not owned by Arlington County.

• Soft Rush (JE)(Juncus effusus)

• Gayfeather (LS)(Liatris spicata)

• Pink Hairgrass (MC)(Muhlenbergia capillaris)

• Shenandoah Switchgrass (PVS)(Panicum virgatum ‘Shenandoah’)

Perennials, Sedges & Grasses

NOTE: Photos are for presentation purposes only and should not be reproduced as they are not owned by Arlington County.

• Woodland Phlox(Phlox divaricata ‘Blue Moon’)

• Short-toothed Mountain Mint (PM)(Pycnanthemum muticum)

• Little Bluestem (SSO)(Schizachrynium scoparium ‘Standing Ovation’)

• New York Ironweed (VN)(Vernonia noveboracensis)

Perennials, Sedges & Grasses

NOTE: Photos are for presentation purposes only and should not be reproduced as they are not owned by Arlington County.

• Virginia Bluebells (MV)(Mertensia virginica)

• Roundleaf Ragwort (PO)(Packera aurea)

Williamsburg BlvdN. Kensington Street

John Marshall Drive Island

Refer to the Green Streets brochure for more information…

Rain Garden Projects in Arlington

Review of Temporary Easements and Next Steps Naudy Martinez, NC Planner

Temporary Easements

• Temporary easements and construction agreements allow the County contractor to access private yards to perform construction-related work, including the relocation of fences, replacement of disturbed sod, and making grade adjustments.

• The County agrees to restore the disturbed area on and adjacent to the Temporary Easement Area as nearly as practicable to its original condition.

• Temporary easements become null and void at the end of the project

• Return by mail after signing and having them notarized by the notary of your choice.

Next steps1. Questions and comments

• Relative to the overall project design • Relative to individual lots

2. Final design plan 90%100%

3. Final design plan mailed to all affected homeowners

4. Temporary easements mailed to affected owners and returned to County

5. Utility relocation

6. Go to bid/Prepare for construction

Contact for NC Project: N Larrimore St and 9th St N, Dominion Hills

Naudy Martinez, NC PlannerCommunity Planning, Housing, & Development

Neighborhood Services Divisionnmartinez(at)arlingtonva.us

(703) 228-7933