Transcript Impacts of Impervious Cover on Aquatic Systems

Surviving the Local WIP:
a practical guide on
nutrient accounting for
the Chesapeake Bay
TMDL
Contact Info
Tom Schueler
Chesapeake Stormwater Network and
EPA Chesapeake Bay Program Stormwater Coordinator
Baltimore, MD
[email protected]
www.chesapeakestormwater.net
www.cbstp.org
Key Topics
• Some nutrient math
• Some basics on the Bay TMDL
• 12 easy steps to comply with your local
load allocation
• Discussion
Technical Bulletin # 9
Nutrient Accounting Methods to Document Local Stormwater
Load Reductions in the Chesapeake Bay
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Nutrients and the Chesapeake Bay
Why we need to become nutrient accountants
What we know about nutrients and stormwater
Tools to estimate nutrient loads
Defining the local baseline load
Pollutant removal rates for urban BMPs *
Strategy for achieving local load reductions
Analyzing the cost of implementation
* official CBP rates and proposed interim planning rates
Urban Nutrients
Where do they come from?
There are many sources of N and P in the urban
environment
Much of the nitrogen in urban runoff is derived
from atmospheric deposition, either in the form
of dryfall or wetfall
Relationship of Atmospheric Deposition
to Urban Runoff Quality
Atmospheric
Stormwater Runoff
Deposition 1
Load 2
Nutrient
Total Phosphorus
Total Nitrogen
Pounds per impervious acre per year
0.7
13 to 17.0
2.0
15.4
measured rates during Washington NURP Study (MWCOG, 1983)
Simple Method annual stormwater runoff loads for one acre of impervious cover
(Schueler, 1987)
1
2
Other sources of nitrogen in
urban runoff include:
• Washoff of fertilizers
• Nitrogen attached to eroded
soils and streambanks
• Organic matter and pet wastes
on IC
What we know about turf and its
management in the Bay Watershed
• 3.8 million acres of turf
• Represents 9.5% of watershed area
• Exceeds area devoted to row crops
(corn, wheat, soybeans)
• 75% of turf is home lawn
Nitrogen EMCs
for different urban land covers
Source; CWP, 2003
Urban Land Cover
Total N (mg/l)
Lawns
9.70
Highway
2.95
Streets (Variable)
1.40
Parking Lots
1.94
Rooftops
1.50
Runoff sampling shows that lawn runoff is very high in
nitrogen. Also, rooftop runoff concentration shows
effect of atmospheric deposition
What do we know about home lawns and nutrients?
About 50% to 65% fertilize their yard
15 to 20% hire lawn care company
Average of two applications per year
50% of homeowners over-fertilize
Estimated N Fertilizer inputs by lawns: 215
million lbs/yr
What have you been hearing about the
Chesapeake Bay TMDL ?
Bottom Line of Chesapeake Bay TMDL
For Urban Suburban Sector
~25 to 30% TP and TN
load reductions needed
from existing
development (plus
sediment reductions)
No increase in future load
as a result of growth and
development
60% of the reductions to
be achieved by 2017
100% by 2025
otos:
Chesapeake
Bay Program
Some folks think the WIP process is scary
• Billions in potential costs
• Short planning horizon (draft plan due Dec 1, 2011)
• Potential regulatory liability
• High planning costs
• Lots of complex documents
= major local headaches
The WIP Process is not as Scary as it Looks
• Each state works with its local governments to
develop strategies for nutrient reduction
• The jurisdictional unit could be a MS4 permitee,
planning district commission, county or conservation
district, depending on the state
• The liability for not meeting the load reductions is
a state liability, and not a local one (unless tied into
MS4 permit)
What to expect:
• Locals will need to submit data, have a
strategy and report on BMP implementation
• Locals will need to follow state and/or CBP
approved procedures for tracking and
verifying BMPs
• States have the responsibility for
aggregating local data and submitting it to
EPA to show progress in load reductions
The WIPs are a long term process
• Progress is assessed based on two year
milestones
• Implementation of the WIP is a 15 year
iterative process
• Many opportunities for adaptive
management and collaboration
Check with your state agency to find who is
responsible for WIPs in your state and the
process they will follow
(they differ a lot)
A practical local strategy to meet the local WIP
Step 1 Organize a local watershed implementation team
BMP Credit
Lead Agency
Other Stakeholders
Watershed Mapping/Planning
Planning, GIS
Local watershed group
Stormwater Retrofits
DPW or stormwater review
agency
Schools, parks, roads,
and other public land
New Development
Stormwater review agency
Land use planning
Maintenance Upgrades
DPW Maintenance crew
CIP budgets
Stream Restoration
Environmental resources
Parks
Redevelopment Credits
Stormwater review staff
Planning agency
Reforestation
Community forestry and
Site planning agencies
Parks, street trees,
schools
Street Sweeping
DPW Maintenance Crew
Street maintenance
Urban Fertilizer Management
MS4 Permit holder
Cooperative Extension
Septic Hookups/Upgrade
Sanitarian
wastewater Utility
Illicit Discharge Elimination
MS4 Permit holder
Watershed groups
Wetland/shoreline Restoration
Local environmental agency
Land conservancy
Initial Tasks for the Watershed Team
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Obtain the local nutrient reduction allocation from the state or regional
agency administering the TMDL
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Coordinate with the state TMDL agency to better understand their
local expectations
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Analyze local land use and land ownership data to determine what part
of their load allocation can be legitimately excluded
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Identify which local agencies or stakeholders have primary
responsibility to implement the dozen available urban BMP credits
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Check to see if agencies are already implementing a credit, or could do
so through modest changes to existing programs.
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Determine how the credits should be documented and reported to the
appropriate state or regional agency
# 2 Take credit for fertilizer reductions on urban turf
• Reflects recent MD and VA P
Ban in Fertilizer
• Modeled as an application
reduction, with an estimated 17
to 19% TP reduction in urban
loads
• Research in other regions put
it closer to 10 to 12%
• TN reductions are minor
unless regional education
campaign program to reduce N
fertilization
Urban Nitrogen
Fertilizer Reduction
Right now, none of our residential
stewardship programs focuses on
reducing urban fertilizer use, despite
the fact it is the most cost effective
nutrient reduction strategy
• 1.5 million acres of home lawn are
fertilized
• Very limited incentives beyond free
soil testing and passive technical
advice
• We send conflicting messages to
homeowners about lawn fertilization
Fertilizer Message 1
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Get a soil test, and if adequate P is
present, then select P-free fertilizer
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Calibrate your spreader
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Follow label directions of weed/feed
products
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Use slow release N fertilizer in Fall only
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Apply 1 to 4 lbs of actual N per 1000
square feet
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Do not apply to frozen soils, impervious
cover or in advance of a thunderstorm
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Use a composting lawn mower and recycle
composted leaves over yard
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Set mower height at three inches
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Irrigate only after extended drought
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Don’t washout your spreader over IC
Fertilizer Message 2
Tommy makes an offer you can’t refuse!
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Keep your spreader in the garage for
the next three years to protect the Bay
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Save 150 bucks and three weekend days
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If you still like the look of your lawn
after three years we will buy back your
spreader for $150
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If you think your lawn looks like crap,
we will pay for a lawn makeover worth
$500 (using our green lawn service)
The Competing Fertilization Message
Consumer surveys indicate the primary and
almost exclusive sources for
information on fertilizing their lawns
are:
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TV and radio commercials
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Product labels in the big box store
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Store attendants
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Recommendation from their lawn care
company
# 3 Take nutrient reduction credits for more stringent
stormwater requirements at redevelopment projects
Calculate the expected
acres of impervious cover
slated for redevelopment
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• Estimate the runoff
capture volume and design
level using new regs
• Calculate the aggregate
nutrient reduction credit
Nutrient Reduction Credits for Redevelopment
Lbs/acre/year
Total P
Rainfall depth for which stormwater treatment is computed (inches)
0.25
0.50
0.75
1.0
1.25
1.5
LO1 HI2 LO
HI
LO
HI
LO
HI
LO
HI
LO
HI
0.4 0.6 0.6 0.9
0.75 1.1
1.0
1.5
1.25 1.65 1.4
1.8
Total N
3.3
Nutrient
4.5
5.1
6.8
6.3
8.4
8.4
11.3
9.9
12.3
11.1
Multiply aggregate acres of redeveloped IC by the per acre load reduction credit
Can be an important strategy in several Bay cities
13.5
# 4 Become an Early Adopter of
Stormwater Regulations
This ensures that your nutrient liability won’t continue to increase
Variability in Bay State Stormwater Regulations
• Considerable confusion in terminology among the
states (ESD, LID, RR, treatment trains)
• Each state/locality is on a different schedule for
implementing them (2009 to 2013)
• Each state has a unique hydrologic performance
standard
• Differential standards for new and redevelopment
• Individual sites may not fully comply with standard
Will the new standards lead to nutrient
neutrality for new development projects in
the future ?
What is an acceptable runoff nutrient load?
TP Loads, By Land Based Sector in Maryland Bay TMDL
Loading Sector
2009 Load
Target Load
Million pounds per year
Forest Runoff
0.35
0.35
Urban and Suburban Runoff
0.67
0.44
Agricultural Runoff
1.44
1.25
ALL RUNOFF SOURCES
2.46
1.99 3
Acceptable Load (lbs/acre)
0.56
0.34
excludes CAFO portion of agricultural runoff
Wastewater sources excluded
Same Analysis Yield an Acceptable TN Load of 4.4 lbs/acre
Results differ slightly for each state based on distance to the
Bay
What local safeguards are needed to ensure the load
limits are actually achieved on the ground?
Practices designed in accordance with
Bay-wide Design Specs
Post-construction certification that it
was installed properly and works
Municipality meets minimum performance
standards for:
ongoing performance inspections
maintenance enforcement
# 5 Take Credit for Community Reforestation
• Set goal to reforest 5% of current turf cover
• 10 to 1 Rule (ten acres of reforestation equals
one acre of impervious cover treated)
• CSN and VADCR spreadsheet rates are about
the same
• Get extra credit for
•Treating runoff from adjacent IC
• Stream or shoreline buffer upgrades ?
# 6 Take credit for current and future
stream restoration projects
• High nutrient reduction
rates for qualifying projects
• Provides both a local
benefit and a Bay benefit
• Generally popular with the
public
• Cost competitive with pond
retrofits
Proposed Interim
Stream Restoration Rate
Removal rate per Linear foot of Qualifying
Stream Restoration
Source
TN
TP
TSS
CBP
2005
N=1
CSN
2011
N=6
otos:
Chesapeake
Bay Program
U of MD
Study
N=25+
0.02 lbs
0.0035
2.55 lbs
0.20 lbs
0.068 lbs
310 lbs
Scheduled for early 2012
CBP BMP Panel to Update Stream
Restoration Rates
• U of MD Literature Review
• Review of 20 + studies on various parts of the urban
stream nutrient cycle
• Develop concept model for predicting rates
• Should be done by early 2012
What’s a Qualifying Project?
Can’t just dump rip-rap
Comprehensive stream design
Flood plain re-connection
Minimum reach size
In-stream habitat features
# 7 Re-tool your stormwater
maintenance program
Inspect the performance of your existing
BMP inventory
Field Research Indicates about 30% of
the BMP Inventory needs a makeover
Significant nutrient reductions are
possible through these low cost “BMP
makeovers”
Performance downgrades must be
reflected in local WIP baseline load
By Retooling existing Maintenance
Budget, it is possible to eliminate
eyesores and clean the Bay
Dealing with the Local BMP Legacy
Thirty Years of BMPs. The BMP Inventory in a Maryland County
Potentially High Performers
Bioretention/Dry Swales
49
Known Low Performers
270
Sand Filters
279
Underground
Detention
Dry Ponds
Wet pond
212
Oil Grit Separators
805
Pond Wetland
98
Proprietary Practices
239
Infiltration Basin
58
Flow Splitter
321
Other (plunge pools)
30
Infiltration Trench
Adapted from MCDEP 2006
459
528
3350
# 9 Take the Mass Credit for
Intensive Street Sweeping
• New CBP Method based on Actual
Pollutant Mass Picked Up
• Qualifying Frequency and Technology
• Incentive for Sweeping Crews to
Maximize Pickup
# 9 Investigate Septic Hookups and Upgrades
• Key Strategy for TN removal
• Relict septics in sewered
catchments
• Upgrade N technology in
existing septics
• Sewer extensions and cluster
satellites
• CBP Rates available
# 10 Take Credit for Eliminating Illicit Discharges
• For chronic and episodic
sewage discharges that are
physically eliminated
• Reduction based on rate of dry
weather flow and outfall
concentration above
background levels
• CWP research indicates this
can be an important strategy
in some urban watersheds
available
# 11 Retrofit Existing Stormwater Ponds
Source: CWP
# 12 Residential LID Retrofits
Subsidies, technical assistance,
stormwater utility credits and
other incentives to build LID
retrofits on private land
The Cost Challenge
The weakest link in local
WIPs are accurate cost
data for practices
Need to acquire better
cost data and share it
Possibility of Bay-wide
database
Millions vs. billions
Discussion: