Donaldson Run Tributary B Stream Restoration Project ... - Arlingtonva
Donaldson Run Tributary B Stream Restoration Project Update June 23, 2010 Washington-Lee High School
‘Big picture’ concepts
Past land use and drainage decisions have severely impacted County streams
Watershed improvements and in-stream restoration efforts are both essential
Urban stream corridor damage must be addressed comprehensively
Stream restoration accomplishes multiple resource management objectives
Neighborhood partnership is essential
Effect of Urbanization on Watersheds
Impervious surface Runoff speed and volume Donaldson Run above Military Road ~30%
Water Quality Groundwater supply
Stream Corridor Restoration, FISRWG, 1998
Most urban streams here
Streams in Stages II and III… •
Continue to erode their banks and beds, sending sediment downstream to smother aquatic habitat and degrade water quality.
•
Damage infrastructure, including sanitary sewers and trails.
•
Are not safe for park users.
•
Undermine trees near the stream.
Tributary A
Tributary A
Tributary B
Tributary B
Sediment and Nutrients
According to EPA…. •Excess
sediment is the primary reason that many of the Bay watershed’s streams are degraded. •Excess sediment suspended in the water is one of the leading causes of the Chesapeake Bay's poor health. •Stream restoration is among the ‘best management practices’ to restore the Bay. •Local governments must reduce sediment and nutrient pollution. http://www.chesapeakebay.net/sediments.aspx?menuitem =14691 http://www.chesapeakebay.net/sediments.aspx?menuitem=14691
Deposition of eroded sediments from Donaldson Run
‘Fixing’ urban streams in the past
The ‘old’ way – using large rocks to armor banks to ‘arrest’ stream in Stages II and III
‘Fixing’ urban streams in the past
Re-shaping banks is another option but stream remains disconnected from floodplain, longterm stability is questionable, and near stream trees are still lost.
‘Fixing’ urban streams in the past ‘Piecemeal’ stabilization techniques may save some trees in the short term, but… • • • • • •
Erosive energy of stream is just shifted elsewhere; Sanitary sewer infrastructure and park trails remain at risk from damaging stream flows; Habitat is compromised further; Stream banks still remain steep and unsafe; A considerable amount of money is still spent; and, Many trees are still impacted by construction.
Tributary A, Segment A2 2003
A Comprehensive Approach: Natural Channel Design Key elements: • • • • • •
Re-connecting Stage II/III stream with new floodplain to reduce erosive power. Grading banks to stable slopes. Controlling stream energy with step pools. More natural stream curvature. Diverse and native vegetation for habitat and stability. Integrated approach for entire stream corridor.
Natural Channel Design Restored stream returned close to here Most urban streams here
Artificial hardening
Undermined trees Floodplain
Straightened channel
Old channel width/depth and floodplain ‘DISCONNECTION’
Tributary A, Segment A2, February 2004
Stage II/III
Floodplain Curvature/meander pattern
Step pool slope control
New channel width/depth and floodplain ‘CONNECTION’ Tributary A, Segment A2, November 2009
Tributary A Stream Restoration: Multiple objective resource management
Dramatic reduction in sediment erosion Protection of infrastructure Safe and accessible recreation Improved in-stream habitat Improved near-stream plant diversity Outreach and education Control of invasive species Improve long-term health of stream valley forest
Sediment Tributary A water with visibly lower sediment content
Tributary B water with visibly higher sediment content
Access and Recreation
Infrastructure Sewer main
Trail
Photo of trail erosion
Number of Macroinvertebrates/Sampling Event in Donaldson Run 100 90
Organisms/sampling events
Restoration completed 80
In-stream Habitat
70 60 50 40 30 20 10
Macro data
N ov ,2 0 M ay 02 ,2 Se 00 pt 3 ,2 0 D ec 03 , M 20 ar ch 03 ,2 Se 00 4 D p ec t em , 20 be 04 r M , 20 ar ch 04 , Ju 200 5 ne ,2 Ju 00 5 O ly, ct 2 ob 00 5 er ,2 0 Ju 05 ly ,2 O 006 ct ,2 D 00 ec 6 M , 20 ar ch 06 ,2 Au 00 g, 7 20 07 Ja n, Ju 08 ne ,0 Se 8 pt ,0 8 D ec ,0 Ap 8 ri l , Ju 09 ne ,0 Se 9 pt , Ap 09 ri l ,1 0
0
• Monitoring since restoration shows encouraging results for improvement of biological community, including overall numbers of organisms, community diversity, and presence of more pollution sensitive insects • Damselfly larvae (an aquatic predator) have been found 4 times since restoration; rarely seen in other County streams
Damselfly in Lee Heights Park
Near stream plant diversity
Tributary A, June 2010
October 2005
Lee Heights Park
June 2010
October 2005
Lee Heights Park
June 2010
Outreach and education
Tributary B
Donaldson Run watershed to Po ma
ry
Tributary C
ad Ro
Dona ldson Run
e eb Gl
Taylor School
Tributary B
r ive
ili ta
ay rkw Pa ton
M
cR
ing ash eW org Ge
Donaldson Run Watershed Boundary
Tributary A ad Ro
e eb Gl ad Ro
KEY PROJECT FACTS: •Approved Neighborhood Conservation Program Project •1,400 linear feet to Upton street •26% impervious cover in watershed •Natural channel design approach
County/Donaldson Run Civic Association Partnership
10+ year partnership
Stream restoration top neighborhood priority
NCAC approved Tributary B funding in December 2007; County Board 2008; DES providing additional funds
Extensive County/DRCA public process: meetings, workshops, stream walks, newsletter articles, park signs, Citizen articles, and other media coverage
Severe bank erosion and floodplain ‘disconnection’
More bank erosion, floodplain disconnection, and exposed sanitary sewer
Exposed sanitary sewer
Trees undermined by bank erosion
Trees undermined by bank erosion
Trees undermined by bank erosion
Stream confined by steep valley wall
Stream confined by bike trail
Widespread growth of invasive plants
Stream Assessment and Design Approach for Tributary B
Most of Tributary B here
Lower section below footbridge here, but curvature not stable
IV B
III/IV G
III/II G
II/III A
II G
II G
Steep valley wall
Existing channel width/depth and floodplain ‘DISCONNECTION’ Stage II/III
Straightened channel Tributary B, November 2009
Steep valley wall
Lower Section Relatively well connected to floodplain but….
Existing channel width/depth and floodplain ‘DISCONNECTION’ …curvature/meander not stable.
Steep valley wall Floodplain ‘benches’
Proposed channel width/depth
Slight curvature/meander pattern
and floodplain ‘CONNECTION’
Tributary B, November 2009
60% Design Update
Key adjustments include:
Reducing width of channel/floodplain to reduce footprint.
Limiting re-location of pathway and narrowing pathway.
Reducing disturbance and tree impacts below the footbridge
Measures to address trailside and valley drainage issues
Two additional drainage pipes to convey water from existing swale that runs along pathway to stream.
Removing concrete channel between trail and stream and creating more natural drainage feature.
Stabilizing eroded ditch between a storm sewer outfall and stream.
Tree removal
7 fewer trees to be removed under current design (73 vs. 80). 11 fewer ‘significant’ (>10” diameter) trees to be removed (37 vs. 48). 17 of 37 significant trees (46%) are in compromised condition. 3 additional trees are invasive Norway maples. Minimum tree replacement = >100 trees.
Trees to be saved near construction zone
32 significant trees with critical root zone impacts but to be saved (8 poor condition; 1 undercut).
Some adjustments to grading and tree protection will occur based on field conditions, and a few more trees may need to be removed as final design proceeds.
At this time, removal of 37 significant trees is a reasonable estimate.
As with Tributary A project, stream valley forest will remain intact and tree canopy will fill in as replacement trees mature
Restored stream with new floodplain Extensive new native plantings Protection of most of existing stream valley trees
Key issues to be addressed in next design phase
Eroding steep slope adjacent to stream.
Comprehensive plan to control invasive plants which cover much of the stream valley.
Comprehensive planting plan for native trees, shrubs, and ground cover.
Locations of step pools to control stream energy.
Developing construction staging and access plan.
Benefits of multiple objective resource management
Nutrient and sediment reductions for local streams and the Bay Protection of infrastructure: trail, sanitary sewer, property Improved in-stream/near-stream habitat, plant diversity, long-term stream valley forest health Improved recreation Outreach and education
Process/Schedule 30% designs
Stakeholder advisory group meeting, November 5, 2009 Streamwalk, November 14, 2009 DRCA meeting, December 2, 2009
60% designs
2nd Stakeholder advisory group meeting - TBD 2nd DRCA meeting - June 23, 2010 2nd streamwalk – TBD
Final design
3rd Stakeholder group meeting/DRCA meeting – Fall 2010
Construction (est. 2011)
For more information contact:
Jason Papacosma Arlington County Dept. of Environmental Services Environmental Management Bureau (703) 228-3613 [email protected] Learn more at: www.arlingtonva.us – search “Donaldson Run.”
Tributary A, June 2010
‘Big picture’ concepts
Past land use and drainage decisions have severely impacted County streams
Watershed improvements and in-stream restoration efforts are both essential
Urban stream corridor damage must be addressed comprehensively
Stream restoration accomplishes multiple resource management objectives
Neighborhood partnership is essential
Effect of Urbanization on Watersheds
Impervious surface Runoff speed and volume Donaldson Run above Military Road ~30%
Water Quality Groundwater supply
Stream Corridor Restoration, FISRWG, 1998
Most urban streams here
Streams in Stages II and III… •
Continue to erode their banks and beds, sending sediment downstream to smother aquatic habitat and degrade water quality.
•
Damage infrastructure, including sanitary sewers and trails.
•
Are not safe for park users.
•
Undermine trees near the stream.
Tributary A
Tributary A
Tributary B
Tributary B
Sediment and Nutrients
According to EPA…. •Excess
sediment is the primary reason that many of the Bay watershed’s streams are degraded. •Excess sediment suspended in the water is one of the leading causes of the Chesapeake Bay's poor health. •Stream restoration is among the ‘best management practices’ to restore the Bay. •Local governments must reduce sediment and nutrient pollution. http://www.chesapeakebay.net/sediments.aspx?menuitem =14691 http://www.chesapeakebay.net/sediments.aspx?menuitem=14691
Deposition of eroded sediments from Donaldson Run
‘Fixing’ urban streams in the past
The ‘old’ way – using large rocks to armor banks to ‘arrest’ stream in Stages II and III
‘Fixing’ urban streams in the past
Re-shaping banks is another option but stream remains disconnected from floodplain, longterm stability is questionable, and near stream trees are still lost.
‘Fixing’ urban streams in the past ‘Piecemeal’ stabilization techniques may save some trees in the short term, but… • • • • • •
Erosive energy of stream is just shifted elsewhere; Sanitary sewer infrastructure and park trails remain at risk from damaging stream flows; Habitat is compromised further; Stream banks still remain steep and unsafe; A considerable amount of money is still spent; and, Many trees are still impacted by construction.
Tributary A, Segment A2 2003
A Comprehensive Approach: Natural Channel Design Key elements: • • • • • •
Re-connecting Stage II/III stream with new floodplain to reduce erosive power. Grading banks to stable slopes. Controlling stream energy with step pools. More natural stream curvature. Diverse and native vegetation for habitat and stability. Integrated approach for entire stream corridor.
Natural Channel Design Restored stream returned close to here Most urban streams here
Artificial hardening
Undermined trees Floodplain
Straightened channel
Old channel width/depth and floodplain ‘DISCONNECTION’
Tributary A, Segment A2, February 2004
Stage II/III
Floodplain Curvature/meander pattern
Step pool slope control
New channel width/depth and floodplain ‘CONNECTION’ Tributary A, Segment A2, November 2009
Tributary A Stream Restoration: Multiple objective resource management
Dramatic reduction in sediment erosion Protection of infrastructure Safe and accessible recreation Improved in-stream habitat Improved near-stream plant diversity Outreach and education Control of invasive species Improve long-term health of stream valley forest
Sediment Tributary A water with visibly lower sediment content
Tributary B water with visibly higher sediment content
Access and Recreation
Infrastructure Sewer main
Trail
Photo of trail erosion
Number of Macroinvertebrates/Sampling Event in Donaldson Run 100 90
Organisms/sampling events
Restoration completed 80
In-stream Habitat
70 60 50 40 30 20 10
Macro data
N ov ,2 0 M ay 02 ,2 Se 00 pt 3 ,2 0 D ec 03 , M 20 ar ch 03 ,2 Se 00 4 D p ec t em , 20 be 04 r M , 20 ar ch 04 , Ju 200 5 ne ,2 Ju 00 5 O ly, ct 2 ob 00 5 er ,2 0 Ju 05 ly ,2 O 006 ct ,2 D 00 ec 6 M , 20 ar ch 06 ,2 Au 00 g, 7 20 07 Ja n, Ju 08 ne ,0 Se 8 pt ,0 8 D ec ,0 Ap 8 ri l , Ju 09 ne ,0 Se 9 pt , Ap 09 ri l ,1 0
0
• Monitoring since restoration shows encouraging results for improvement of biological community, including overall numbers of organisms, community diversity, and presence of more pollution sensitive insects • Damselfly larvae (an aquatic predator) have been found 4 times since restoration; rarely seen in other County streams
Damselfly in Lee Heights Park
Near stream plant diversity
Tributary A, June 2010
October 2005
Lee Heights Park
June 2010
October 2005
Lee Heights Park
June 2010
Outreach and education
Tributary B
Donaldson Run watershed to Po ma
ry
Tributary C
ad Ro
Dona ldson Run
e eb Gl
Taylor School
Tributary B
r ive
ili ta
ay rkw Pa ton
M
cR
ing ash eW org Ge
Donaldson Run Watershed Boundary
Tributary A ad Ro
e eb Gl ad Ro
KEY PROJECT FACTS: •Approved Neighborhood Conservation Program Project •1,400 linear feet to Upton street •26% impervious cover in watershed •Natural channel design approach
County/Donaldson Run Civic Association Partnership
10+ year partnership
Stream restoration top neighborhood priority
NCAC approved Tributary B funding in December 2007; County Board 2008; DES providing additional funds
Extensive County/DRCA public process: meetings, workshops, stream walks, newsletter articles, park signs, Citizen articles, and other media coverage
Severe bank erosion and floodplain ‘disconnection’
More bank erosion, floodplain disconnection, and exposed sanitary sewer
Exposed sanitary sewer
Trees undermined by bank erosion
Trees undermined by bank erosion
Trees undermined by bank erosion
Stream confined by steep valley wall
Stream confined by bike trail
Widespread growth of invasive plants
Stream Assessment and Design Approach for Tributary B
Most of Tributary B here
Lower section below footbridge here, but curvature not stable
IV B
III/IV G
III/II G
II/III A
II G
II G
Steep valley wall
Existing channel width/depth and floodplain ‘DISCONNECTION’ Stage II/III
Straightened channel Tributary B, November 2009
Steep valley wall
Lower Section Relatively well connected to floodplain but….
Existing channel width/depth and floodplain ‘DISCONNECTION’ …curvature/meander not stable.
Steep valley wall Floodplain ‘benches’
Proposed channel width/depth
Slight curvature/meander pattern
and floodplain ‘CONNECTION’
Tributary B, November 2009
60% Design Update
Key adjustments include:
Reducing width of channel/floodplain to reduce footprint.
Limiting re-location of pathway and narrowing pathway.
Reducing disturbance and tree impacts below the footbridge
Measures to address trailside and valley drainage issues
Two additional drainage pipes to convey water from existing swale that runs along pathway to stream.
Removing concrete channel between trail and stream and creating more natural drainage feature.
Stabilizing eroded ditch between a storm sewer outfall and stream.
Tree removal
7 fewer trees to be removed under current design (73 vs. 80). 11 fewer ‘significant’ (>10” diameter) trees to be removed (37 vs. 48). 17 of 37 significant trees (46%) are in compromised condition. 3 additional trees are invasive Norway maples. Minimum tree replacement = >100 trees.
Trees to be saved near construction zone
32 significant trees with critical root zone impacts but to be saved (8 poor condition; 1 undercut).
Some adjustments to grading and tree protection will occur based on field conditions, and a few more trees may need to be removed as final design proceeds.
At this time, removal of 37 significant trees is a reasonable estimate.
As with Tributary A project, stream valley forest will remain intact and tree canopy will fill in as replacement trees mature
Restored stream with new floodplain Extensive new native plantings Protection of most of existing stream valley trees
Key issues to be addressed in next design phase
Eroding steep slope adjacent to stream.
Comprehensive plan to control invasive plants which cover much of the stream valley.
Comprehensive planting plan for native trees, shrubs, and ground cover.
Locations of step pools to control stream energy.
Developing construction staging and access plan.
Benefits of multiple objective resource management
Nutrient and sediment reductions for local streams and the Bay Protection of infrastructure: trail, sanitary sewer, property Improved in-stream/near-stream habitat, plant diversity, long-term stream valley forest health Improved recreation Outreach and education
Process/Schedule 30% designs
Stakeholder advisory group meeting, November 5, 2009 Streamwalk, November 14, 2009 DRCA meeting, December 2, 2009
60% designs
2nd Stakeholder advisory group meeting - TBD 2nd DRCA meeting - June 23, 2010 2nd streamwalk – TBD
Final design
3rd Stakeholder group meeting/DRCA meeting – Fall 2010
Construction (est. 2011)
For more information contact:
Jason Papacosma Arlington County Dept. of Environmental Services Environmental Management Bureau (703) 228-3613 [email protected] Learn more at: www.arlingtonva.us – search “Donaldson Run.”
Tributary A, June 2010
