Sparrow Pond Restoration DEPARTMENT OF ENVIRONMENTAL SERVICES - - PowerPoint PPT Presentation
Sparrow Pond Restoration DEPARTMENT OF ENVIRONMENTAL SERVICES ARLINGTON COUNTY OCTOBER 1, 2019 Sparrow Pond Overview Background and Current Conditions Public Process Key Concerns from First Meeting Design Highlights Pond Wildlife (David
DEPARTMENT OF ENVIRONMENTAL SERVICES ARLINGTON COUNTY OCTOBER 1, 2019
Background and Current Conditions Public Process Key Concerns from First Meeting Design Highlights Pond Wildlife (David Howell) Next Steps
Dog park
Glencarlyn Forest Glen Arlington Mill Arlington Forest Barcroft
1990s: Assessment of “Sparrows Swamp” 2001-02: Pond areas were installed to provide habitat and water quality benefit 2003-2012: Pond fills in with sediment, cleaned out at least once 2012: Maintenance was deferred in favor of a redesign and restoration 2016: Feasibility study for restoration 2017-18: Embankment study and geotechnical analysis 2019-20: Design (30%, 60%, 90%, 100%) 2021-22: Construction (6-9 months)
Goals of the restoration:
Meet requirements and goals for Chesapeake Bay pollution diet and Stormwater permit Implement Stormwater Master Plan (2014)
facilities
nutrients to the Chesapeake Bay
– it’s working, but we can’t let up!
Total Drainage Area: 80.76 acres Forest/Open Space: 13 acres, 16% Turf: 35 acres, 44% Impervious Surface: 32 acres, 40%
30% design Survey & Site analysis Utility investigation Hydraulic study 60% design More design details Wetland delineation 90% design Maintenance of Traffic Planting plan 100% and Final Design Plan Finalize permits Finalize maintenance agreement Pre Construction: Invasive species removal Plant & animal rescue
March 2019 October 2019 Spring 2020 Fall 2020
Forebay traps sediment Allows sediment to settle out of the water column Facilitates maintenance
Image: Virginia Best Management Practice Clearinghouse, 2011
Aquatic Benches
http://grant-associates.uk.com/projects/suds-manual/
10 foot wide access path next to W&OD trail Limit impacts on the trail 6” of gravel below surface
Maintenance access path Vegetated surface, permeable sub-base
Forebay Aquatic benches and other habitat features Provide more nutrient removal and water quality benefit Safely detain 100 year flood event (1% chance of happening each year) The new area was disturbed during the 2001-02 pond construction, used to deposit dredged sediment.
Trees were surveyed, mapped and classified by priority Factors for priority:
Next step: identify ways the design could be adjusted to limit tree impact, especially with moderate priority trees Tree and replanting information at next meeting Wetland Studies and Solutions, Inc is supporting the tree surveys, planting and wetland permitting work.
Tree Preservation Priority Removals
(Initial figures)
High Priority for Preservation 0* Moderate Priority for Preservation 21 Low Priority for Preservation 55 Trees Not Recommended for Preservation
(11 dead, 1 critical, 15 poor)
27 Total 103 * All high priority trees will be preserved.
Preliminary (Draft) Tree Survey
By request, this slide was added to the online PDF after the presentation was given.
Looking to work with partners in Parks to identify potential frog breeding habitat area
water free of fish predators.
Challenges: If inline with pond and stream, fish will be able to enter from the pond If not inline with pond and stream, the area will be fed by only runoff and may not accumulate enough water
Replace with public-friendly version – Jon is preparing
30% design Survey & Site analysis Utility investigation Hydraulic study 60% design Design details Wetland delineation 90% design Maintenance of Traffic Planting plan 100% and Final Design Plan Finalize permits Finalize maintenance agreement Pre Construction: Invasive species removal Plant & animal rescue
What do you like about the design? What should we take into account moving forward?
What additional information would you like to see in future meetings?
spring 2020
Lily Whitesell lwhitesell@arlingtonva.us 703-228-3042 Ty Asfaw, Project Manager tasfaw@arlingtonva.us 703-228-3959