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Urban Stream Restoration Protocols
& Frequently Asked Questions
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Speaker Info
Bill Stack, Center for Watershed Protection, [email protected]
Lisa Fraley-McNeal, Center for Watershed Protection, [email protected]
Josh Burch, District Department of the Environment, [email protected]
Cecilia Lane, Chesapeake Stormwater Network, [email protected]
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Today’s Agenda
• Stream Restoration Crediting for Meeting Sediment and Nutrient Goals in the Chesapeake Bay
• Case Study: Nash Run Stream Restoration Project
Poll Question #1
Tell us a little about yourselves…who are you representing today?
• Design professional • MS4 Phase 1 • MS4 Phase 2 • State government • Federal government • Other – tell us in the chat box
Poll Question #2
What is your role as it relates to stream restoration projects?
• I design them
• I construct them
• I permit them
• I will be involved in the nutrient accounting for a MS4 in order to meet the Bay TMDL
Poll Question #3
How many people are watching with you today?
• Just me
• 2-5 people
• 6-10 people
• > 10 people
Stream Restoration Crediting for Meeting Sediment and Nutrient Goals in the
Chesapeake Bay
Bill Stack
Lisa Fraley-McNeal
April 24, 2014
The Panel Process
• Outlined in the BMP Review Protocol (WQGIT, 2010)
• BMP Expert Panel reviews existing research set of recommendations
• 7 calls, 2 workshops, 5 drafts over 12 months
• Product: Technical Memo and 5 Appendices approved by Water Quality GIT May 2013
• 6 Month Test Drive and Mid-Atlantic Stream Restoration Conference with revisions approved by Expert Panel January 2014
Removal Rate per Linear Foot of Qualifying Stream Restoration
Source TN TP TSS
Spring Branch N=1
0.02 lbs 0.0035 2.55 lbs
At some point applied to non-urban stream restoration projects.
Review of the Old Rate
Initial CBP-Approved Stream Restoration Credit (2003)
Edge-of-Stream 2011 Interim Approved Removal Rates per Linear Foot of Qualifying Stream Restoration (lb/ft/yr) Source TN TP TSS*
New Interim CBP Rate
0.20 0.068 310 (54.2)
Revised Interim Rate
0.075 0.068 248 (43.4)
Derived from six stream restoration monitoring studies: Spring Branch, Stony Run, Powder Mill Run, Moore's Run, Beaver Run, and Beaver Dam Creek located in Maryland and Pennsylvania *The removal rate for TSS is representative of edge-of-field rates and is subject to a sediment delivery ratio in the CBWM to determine the edge-of-stream removal rate. Additional information about the sediment delivery ratio is provided in Appendix B.
Approved Interim Rate Used for planning purposes and for projects that do not conform to the protocol requirements.
Stream Restoration Protocols
1. Prevented sediment approach 2. In-stream denitrification
3. Flood plain reconnection 4. The “tweener” Dry Channel RSC
Protocol 1: Credit for Prevented Sediment during Storm Flow
This protocol provides an annual mass nutrient and sediment reduction credit for qualifying stream restoration practices that prevent channel or bank erosion that would otherwise be delivered downstream from an actively enlarging or incising urban stream.
• Estimate stream sediment erosion rates • Convert erosion rates to nitrogen and phosphorus loadings • Estimate reduction efficiency attributed to restoration
Recommended Methods
Monitoring Surveyed cross sections, bank pins…
BANCS method
With validation Alternative modeling approach
Or other methods with validation (e.g., CONCEPTS, BSTEM, stepwise regression)
Step1.Estimate Stream Sediment Erosion Rates Using the BANCS Method
Protocol 1: Credit for Prevented Sediment during Storm Flow
Streambank Characteristics used to develop BEHI
Velocity Gradient and Near-Bank Stress Indices
Regional Curve for Determining “R” in equation: S = ∑(C×A×R)
Curve for Hickey Run – Washington DC- USFWS
Protocol 1: Credit for Prevented Sediment during Storm Flow
Protocol 1: Credit for Prevented Sediment during Storm Flow
S=∑(c x A x R ) / 2,000
• Where: S = sediment load (ton/year) for reach or stream
• c = bulk density of soil (lbs/cubic foot)
• R = bank erosion rate (feet/year) (from regional curve)
• A = eroding bank area (square feet)
• 2,000 = conversion from lbs to tons
Step 2.Convert erosion rates to loadings
Multiply sediment load by TN and TP concentration in streambank sediment.
Protocol 1: Credit for Prevented Sediment during Storm Flow
Step 3.Use conservative 50% reduction efficiency based on local data, literature values or anecdotal observations by practitioners Reduction efficiencies greater than 50% can be used if supported by monitoring data.
This protocol provides an annual mass nitrogen reduction credit for qualifying projects using empirical measurements of denitrification during base flow within a stream's hyporheic zone (stream, riparian and floodplain)
Protocol 2: Credit for Denitrification in the Hyporheic Zone during Base Flow
Functional ecomorphology: Feedbacks between form and function in fluvial landscape ecosystems. Stuart G. Fisher, , James B. Heffernan, Ryan A. Sponseller, Jill R. Welter
Protocol 2: Credit for Denitrification in the Hyporheic Zone during Base Flow
5 feet + stream width + 5 feet
5 feet depth
Step 1.Determine the total post construction stream length that has been reconnected using the bank height ratio of 1.0 or less (for NCD) or the 1.0 inch storm (other design approaches that do not use the bank full storm) Step 2. Determine the dimensions of the hyporheic box Step 3. Multiply the hyporheic box mass by the unit denitrification rate
Qualifying Condition: Nitrogen removal credit cannot exceed 40% of the total watershed TN load.
Annual mass nutrient reduction credit for projects that reconnect stream channels to their floodplain over a wide range of storm events
Protocol 3: Credit for Floodplain Reconnection
Protocol 3: Credit for Floodplain Reconnection
Channel flow
Floodplain flow treated
Excess floodplain flow
Protocol 3: Credit for Floodplain Reconnection Volumes
Step 1. Estimate the floodplain connection volume Step 2.Estimate the N and P removal rate attributable to floodplain reconnection (using Jordan 2007 study)
Protocol 3: Credit for Floodplain Reconnection Volumes
Smaller storm events do not generate runoff.
10% runoff event is the storm at which 90% of total runoff is greater than.
50% runoff event is the storm at which 50% of total runoff is greater than.
Protocol 3: Credit for Floodplain Reconnection Volumes
Step 1. Estimate the floodplain connection volume Step 2.Estimate the N and P removal rate attributable to floodplain reconnection (using Jordan 2007 study)
Protocol 3: Credit for Floodplain Reconnection Volumes
Step 3.Compute the annual N, P, and TSS load delivered to the project
Edge of Stream Unit Loading Rates for Bay States Using CBWM
v. 5.3.2
No Action Run, State-wide Average Loading Rates,
average of regulated and unregulated MS4 areas
BAY
STATE
Total
Nitrogen
Total
Phosphorus
Suspended
Sediment
Pounds/acre/year Tons/acre/year
IMPERV PERV IMPERV PERV IMPERV PERV
DC 13.2 6.9 1.53 0.28 1165 221
DE 12.4 8.7 1.09 0.25 360 42
MD 15.3 10.8 1.69 0.43 1116 175
NY 12.3 12.2 2.12 0.77 2182 294
PA 27.5 21.6 2.05 0.61 1816 251
VA 13.9 10.2 2.21 0.60 1175 178
WV 21.4 16.2 2.62 0.66 1892 265
Source: Spreadsheet output provided by Chris Brosch, CBPO, 1/4/2012
Step 4.Multiply the pollutant load by the project removal rate to define the reduction credit
Protocol 3: Credit for Floodplain Reconnection Volumes
The maximum ponded volume in the floodplain that receives credit is 1 foot to ensure interaction between runoff and wetland plants. There is a minimum watershed to floodplain surface area ratio of 1% to ensure adequate hydraulic detention time. The credit is discounted proportionally for projects that cannot meet this criterion.
Study by Jordan, Smithsonian Environmental Research Center, as published in Weammert and Simpson, 2009. The proportion of TN and TP removed increases with the proportion of wetland area, but the rate of increase declines as the proportion of wetland area increases. Thus, the additional benefit of adding more wetland area gradually diminishes.
Relationship between nutrient removal and ratio of wetland area to watershed area
Wetland Area (% of Watershed)
Design Examples and Comparison to Interim Rate
Design examples were created to show the application of the four protocols. Depending on the project design, more then one protocol may apply. Protocol 1 – Bay City, VA is planning on restoring 7,759 ft of Hickey Run. The data used for this example are taken from Hickey Run collected by the USFWS. Protocol 2 – Bay City would like to determine what additional nutrient reduction enhancement credits could be earned by incorporating in-stream design features that promote biological nutrient processing. It was determined that in-stream design features were possible for 500 ft of the stream and only on one side of the channel. Protocol 3 – Bay City is not satisfied with the credits from the above restoration approaches and wants to compare these approaches to one where the stream can be reconnected to the floodplain. The watershed area is 1,102 acres with an impervious cover of 41%.
Design Examples and Comparison to Interim Rate
Edge-of-Stream Load Reductions for Various Treatment Options (lb/year)
Protocol 1 (BANCS)1
Protocol 2 (Hyporehic Box)2
Protocol 3 (Floodplain Reconnection)3
Total Load Reduction from Protocols 1-3
Revised Interim Rate4
TN
1,538 73 452 2,063 582
TP
708 -- 70 778 528
TSS5 236,000 -- 22,600 258,600 336,741
1 For the design conditions as outlined in protocol 1 example 2 For the design conditions as outlined in protocol 2 example 3 For the design conditions as outlined in protocol 3 example 4 Applying the revised unit rate to 7,759 linear feet of the project 5 For Protocol 1 and interim methods for TSS reductions, a sediment delivery ratio of 0.175 was applied.
Main Concerns Identified during the “Test-Drive” Process
General Concerns
– The protocols are too complicated and difficult to use for planning purposes.
– The interim rate leads to load reductions that can exceed watershed loading rates and may preclude the use of more robust protocols.
Protocol 1 Concerns
– The BANCS method may not be accurate and regional curves have not been developed.
– The 50% efficiency requirement is too low.
– Confusion over application of the sediment delivery factor.
Protocol 2 Concerns
– Certain types of projects result in load reductions that can exceed watershed loading especially for Protocol 2.
Protocol 3 Concerns
– The curves used to develop Protocol 3 are not accurate enough for design purposes.
– The pre-restoration condition was not accounted for.
– Confusion over how upstream BMPs will affect load to the project and subsequently the credit received.
– Confusion over why the baseflow TN credit from Protocol 2 is not added to the credit from Protocol 3.
Qualifying Conditions
Stream restoration projects that are primarily designed to protect public infrastructure by bank armoring or rip rap do not qualify for a credit.
The urban stream reach must be greater than 100 feet in length
The project must utilize a comprehensive approach to stream restoration
design, involving the channel and banks.
Stream restoration project must provide a net watershed removal benefit in order to be eligible for either a sediment or nutrient credit.
No removal credit will be granted for any project that is built to offset, compensate, or otherwise mitigate for an impact to a stream or waterway elsewhere in the watershed
Environmental Concerns Each project must comply with all state and federal permitting requirements. Stream restoration should not be implemented for the sole purpose of nutrient
or sediment reduction.
A qualifying project must meet certain presumptive criteria to ensure that high- functioning portions of the urban stream corridor are not used for in-stream stormwater treatment (i.e., where existing stream quality is still good).
Stream restoration should be directed to areas of more severe stream
impairment, and the use and design of a proposed project should also consider the level of degradation, the restoration needs of the stream, and the potential functional uplift.
Before credits are granted, stream restoration projects will need to meet post-
construction monitoring requirements, document successful vegetative establishment, and conduct initial project maintenance.
A qualifying project must demonstrate that it will maintain or expand riparian
vegetation in the stream corridor, and compensate for any project-related tree losses in project work areas.
All qualifying projects must have a designated authority responsible for
development of a project maintenance program that includes routine and long-term maintenance.
Initial Verification of Performance
Prior to submitting the load reduction to the state tracking database, the installing agency will need to provide a post-construction certification that the stream restoration project: was installed properly, meets or exceeds its functional restoration objectives hydraulically and vegetatively stable,
Initial verification is provided either by the
designer, local inspector or state permit authority
Verification of Stream Restoration Credit
• Max duration for the removal credits is 5 years
• Credit is renewed based on a field performance inspection that verifies the project still exists, is adequately maintained and operating as designed.
• Credit is lost if project cannot be verified (i.e., does not pass inspection).
• This creates strong incentive for localities to monitor the long term performance of their projects
Next Steps
Appendix F to be completed this spring/summer that addresses modeling concerns.
STAC Workshops: Designing Sustainable Stream Restoration Projects (May 2014) and The Peculiarities of Perviousness (April 2014).
Updates for Phase 6 of the Chesapeake Bay Watershed Model
User Training?
Q & A
Photo Credit: Severn Riverkeeper
Sediment & Nutrient Removal Projections
Nash Watershed Map
Nash Run
Present Site Conditions Watershed size: 0.7 sq
miles
Project Length: 1430ft
Stream Length: 1292.2ft
Private Properties: 50+
Load to the Anacostia: 33.5 tons/yr. erosion
FEMA 100yr. Floodplain
Trash
Poor In-Stream Habitat Bank Erosion
Upstream Trash Trap
Floodplain Reconnection Design Create a low floodplain
bench in relation to current stream elevation
Remove 9500 cubic yards of stream bank
Create 6” floodplain on both sides of stream
Highly connected riparian zone
Protocols Used Protocol 1: Prevented Sediment
345ft monitored segment over 15 months with bank pins and soil testing
Protocol 2: In-Stream Nutrient Processing
Estimated hyporeic zone calculation
Protocol 3: Floodplain Reconnection
Too small of an area for watershed size (0.22% floodplain area to watershed size)
Protocol 4: Dry Channel RSC
Protocol 1 Project Length: 1269.2 linear feet.
Monitored Length: 345 linear feet, or 27 percent Nash Run.
Calculation: The computed total annual stream bank erosion rates extrapolated from the existing stream bank monitoring data is as follows:
(33.5 tons/yr) / (345 ft) = 0.0971 tons/yr/ft
1269.2 ft* 2 * 0.0971 tons/yr/ft = 246.4 tons/yr
Reductions- Nitrogen: 295.8 lbs/yr.; Phosphorus: 94.9 lbs/yr.; and TSS: 123.2 tons/yr. based on an avg. soil density value of 2600 lbs / cubic yard (conversion factor of 1.3 for yd3 to tons for avg. materials w/ a 50% efficiency rate).
Protocol 2 Stream Length: 1269.2 feet
Channel Width: 10 feet
Calculations:
1. [(5 ft) + (10 ft) + (5 ft)] * 5 ft * 1269.2 ft = 126,920 ft3 (vol. hyporheic box)
2. 126,920 ft3 * / 27 ft3 /cy = 4700.7 cy
3. (4700.7 cy * 2600 lbs/cy) / 2000 lbs/ton = 6,111 tons
4. 0.000106 lbsN/ton/day * 6111 tons * 365 day/yr = 236.4 lbs nitrogen/yr
Protocol 3 Watershed Area: 467.2 acres
Estimated Floodplain Area: 1.05 acres
Floodplain/Watershed: .22% (not the 1% threshold needed)
Credit is miniscule due to small floodplain to watershed area ratio.
Floodplain reconnection design but not much floodplain reconnection credit
Load Reduction Comparison Method TN TP TSS
Old Rate 50.8 lbs/yr 8.8 lbs/yr 6472.9 lbs/yr
Interim Rate 190.4 lbs/yr 172.6 lbs/yr 110,166.6 lbs/yr
Protocol 1 295.8 lbs/yr 94.9 lbs/yr 246,482 lbs/yr
Protocol 2 236.4 lbs/yr
Protocol 3 0.08 lbs/yr 0.01 lbs/yr 4.90 lbs/yr
Protocol 1+2+3 532.3 lbs/yr 94.9 lbs/yr 246,487 lbs/yr
Lessons Learned Accuracy vs. Simplicity
Include calculations in design scopes of work
Training needed
Must do it to learn it
Big Thanks!!!
Q & A
Photo Credit: LandStudies
Webcast Resources
• CBP Expert Panel Recommendations
• Stream Restoration Verification Guidance • Urban BMP Verification Guidance document
• Appendix G: Clarifications and Edits Resulting from the “Test Drive Period”
www.chesapeakestormwater.net
CSN’s 2014 Webcast Series No. Date Series Topic
2 March 27 Advanced Stormwater Design Bioretention & Dry Swales
3 April 3 Advanced Stormwater Design Permeable Pavement
4 April 24 MS4 Implementers and the Bay TMDL
Stream Restoration
5 May 1 Advanced Stormwater Design Infiltration
6 May 8 MS4 Implementers and the Bay TMDL
Urban Nutrient Management
7 May 29 Advanced Stormwater Design The Real Dirt! (Soils and Soil Amendments)
8 June 5 Advanced Stormwater Design Constructed Wetlands
9 June 12 Advanced Stormwater Design Rainwater Harvesting
10 June 19 MS4 Implementers and the Bay TMDL
TBD
11 June 26 Advanced Stormwater Design Grass Channels, Filter Strips & Disconnections
http://chesapeakestormwater.net/events/categories/2014-webcast-series/
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