Deriving Reliable Pollutant Removal Rates for Municipal Street Sweeping and Storm Drain Cleanout Programs

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Deriving Reliable Pollutant Removal Rates for
Municipal Street Sweeping and Storm Drain
Cleanout Programs

• A project funded by U.S. EPA Chesapeake Bay
  Program
• Urban Stormwater Work Group
• June 27, 2006

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About the Center forWatershed Protection

• Non-profit 501(c)3, non-advocacy organization
• Work with watershed groups, local, state, and
  federal governments
• Provide tools communities need to protect
  streams, lakes, and rivers
• 20 staff in Ellicott City, MD
• www.cwp.org
• www.stormwatercenter.net

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Project Partners

• UMBC (Engineering, CUERE)
• City of Baltimore, DPW
• Baltimore County, DEPRM
• USDA Forest Service, Baltimore Ecosystem Study

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Topics to be Covered

• Purpose of the study
• Nature of the study area
• Project study tasks
• Initial pollutant removal rates
• Findings from Chesapeake Bay survey
• Other CWP resources

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Study Purpose

• Muncipalities are sweeping and cleaning storm
  drains can it make a difference in reducing
  nutrient loads to Bay?
• Very limited and conflicting data on the
  performance of these practices in removing
  nutrients and other pollutants
• Need more reliable estimates of the potential
  nutrient and sediment reductions achieved by
  municipal street sweeping and storm drain
  cleanouts

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Watershed 263
Catchment F
Watershed 263
Catchment O
Location Map
Watershed 263 Catchments
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Catchment characteristics Catchment characteristics Catchment characteristics
F O
Total Area (Acres) 38.4 38.7
Impervious Cover 68 77
Pervious Cover 32 23
Catchment F
Catchment O
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Assessment of Relative Dirtiness of Streets in
Catchment O (CWP 2005)
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Storm EMCs for TSS, TN and TP
Median pretreatment water quality Median pretreatment water quality Median pretreatment water quality Median pretreatment water quality Median pretreatment water quality Median pretreatment water quality
Parameter (mg/L) Catchment O Stormflow Catchment O baseflow Catchment F stormflow Catchment F Baseflow National Storm EMC
Suspended Solids 93.0 3.0 52.0 9.0 58.0
Total P 0.33 0.40 0.30 0.07 0.27
Total N 3.2 5.62 2.11 2.60 2.0
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Streets and Storm Drain Inlet Conditions
The Bad
The Ugly
The Good
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Project Study Tasks

• Task 1 Literature Review and Reference
  Tracking
• System
• Task 2 Basin-wide Municipal Practices Survey
• Field monitoring program
• Task 3 Paired Street Sweeping Treatment
• Task 4 Street Source Area Sampling
• Task 5 Characterization of Stormdrain
  Sediment

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Catchment Monitoring

• Street Sweeping Treatments

Rain gauge at Harlem Park E.S.
Elgin Whirlwind vacuum Street sweeper
Water quality sampling (ISCO sampling station)
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Street Sweeping Treatments

• Catchment F
• Treatment 1 moderate street sweeping effort
  (status quo)
• Treatment 2 85 reduction in curb miles swept.
  

• Catchment O
• Treatment 1 moderate street sweeping effort
  (status quo)
• Treatment 2 48 increase in curb miles swept
• Treatment 3 48 increase in curb miles swept
  and storm drains cleanout

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Task 4 Source Area Sampling of Streets

• 4 treatment street sections
• 2 controls street sections
• 3 samples types
• S after street sweeping
• A accumulation
• W washoff

(From Burton and Pitt 2001)
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Task 5 Characterization of storm drain sediment

• 100 accumulation samples

Accumulation rate sample design. Accumulation rate sample design. Accumulation rate sample design.
Residential Commercial/Industrial
Gwynns Falls (Piedmont) 25 inlets 25 inlets
Baltimore Harbor (Coastal Plain) 25 inlets 25 inlets
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Task 5 Characterization of storm drain sediment

• Total 100 accumulation samples
• Subset 16 for chemical analyses
• TSS, TS
• TKN, NO2NO3
• TP, PO4
• BOD, COD
• Total Cu, Pb, Zn, Cd

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Street Sweeping Review Key Findings

• 75 monitoring and modeling studies were reviewed
  from the 1970s to present
• Few studies provided sufficient data to quantify
  a removal rate
• Considerable differences in scope, extent and
  design of field or modeling studies.
• Pollutant removal rates vary widely based on
  sweeping frequency, sweeper technology and
  operation, street conditions, and the chemical
  and physical characteristics of street dirt.
• New street sweeping technology can pick up more
  than 90 of street dirt under ideal conditions,
  BUT does not guarantee water quality improvements

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Review of Catchbasin Studies

• Only a handful of studies monitored the pollutant
  reduction and the optimal frequencies for
  cleanouts at a catchment scale.
• Cleanouts may reduce pollutants by 5 to 25
  depending on catchment conditions, cleaning
  frequency and type of pollutant.
• Pollutant removal capability of catchbasins is
  constrained by the design which retains coarse
  grained sediments but bypass finer grained
  sediment (containing higher loads of nutrients).

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Conceptual Model

• Conceptual model was developed to provide interim
  pollutant removal rates for TSS, TN and TP. The
  bounding conditions and assumptions were made
  based on the literature

Whats available to be picked up by street Sweeper
How well can the street sweeper remove the
street dirt?
Whats on the streets
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STREET DIRT LOAD Runon () Atmospheric Deposition
() Vehicle Emissions () Littering () Sanding
() Breakup of Street () Organic Matter ()
Others ()
TREATABLE LOAD Washoff (-) Unswept Areas
(-) Street Cracks (-) Curb (-)

SWEEPER EFFECTIVENESS Frequency Technology Street
Condition Operator Effort
DISPOSED STREET DIRT lb/curb-mile
INLET TRAPPING EFFICIENCY Type of Inlet Capacity
of Inlet
CLEANOUT EFFECTIVENESS Frequency Removal Method
DISPOSED SEDIMENT lb/square feet
LEGEND () Processes and material contributing
to street dirt load (-) Processes and
factors that remove street dirt or is
not picked-up by street sweepers
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Interim Pollutant Removal Rates for Sweeping

• Discounted for
• Solubility
• Washoff fugitive dust loss
• Runon
• Frequency
• Technology
• Parked cars
• Street conditions

Frequency TP removal
Monthly 4
Twice a month 5
Weekly 5
Twice a Week 8
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Interim Rates for Catchbasin Cleanouts
Frequency of cleanout TN Removal
Annual 5
Semi-annual 10

• Discounted for
• Frequency
• Particle size distribution of dirt load
• catch basin or inlet full
• Cleanout method

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CB Municipal Practice Survey

• 4 sections
• 43 questions
• Community condition
• Street Sweeping practice
• Stormdrain maintenance
• Monitoring
• 73 response rate

Distribution of 37 surveys
Phase I communities and agencies (23, 16) 11 Maryland 11 Virginia 1 Pennsylvania Phase II permit communities (6, 4) 1 Maryland 3 Virginia 1 West Virginia Greater United States (8, 7) Pennsylvania, Wisconsin, Minnesota, Florida, Texas, California
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Street Sweeping Findings

• 14.75 to 75/curb mile
• 85 of Phase I and II communities sweep more
  frequently than annually (17)
• How frequent?

What proportion of public streets are swept at least on an annual basis? What proportion of public streets are swept at least on an annual basis? What proportion of public streets are swept at least on an annual basis? What proportion of public streets are swept at least on an annual basis? What proportion of public streets are swept at least on an annual basis?
Proportion 100 76-99 50-75 Up to 50
Response 41.2 (7) 11.8 (2) 29.4 (5) 17.6 (3)
no data for 3 surveys One community indicated different proportion of streets for urban vs rural. no data for 3 surveys One community indicated different proportion of streets for urban vs rural. no data for 3 surveys One community indicated different proportion of streets for urban vs rural. no data for 3 surveys One community indicated different proportion of streets for urban vs rural. no data for 3 surveys One community indicated different proportion of streets for urban vs rural.
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Percentage of communities (not streets) that
sweep streets more frequently than 1x/yr
2x/year (14)
Other (26)
Monthly (20)
Daily (14)
2x/month (9)
Weekly (17)
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Most Common Street Sweeping Technology used by
Phase I CB Communities (n17)
Total surveys responded to this questions is 16,
but one community had an equal number of two
different technologies.
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Key Findings Storm drain cleanout

• Of 20 responses,
• 8 regular schedule cleanouts
• 12 response to complaints or clogging
• 1.39/linear ft 55/catchbasin

What proportion of all storm drains, inlets or catch basins are cleaned out on an annual basis? (n16) What proportion of all storm drains, inlets or catch basins are cleaned out on an annual basis? (n16) What proportion of all storm drains, inlets or catch basins are cleaned out on an annual basis? (n16) What proportion of all storm drains, inlets or catch basins are cleaned out on an annual basis? (n16) What proportion of all storm drains, inlets or catch basins are cleaned out on an annual basis? (n16)
Proportion 100 75 lt 100 50lt 75 Up to 50
Response 0 6.3 (1) 31.3 (5) 62.5 (10)

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Most Common Storm Drain Cleanout Methods (n27)
Total surveys responded to this questions is 16,
but some communities indicated more than one
type of technology
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Next Steps

• Review Requested on Memos 1 2
• Close gaps
• Planned work next 6 to 9 months
• Source area sampling of streets
• Sediment data from County
• Load estimates from Catchments O and F (DPW)
• Refine pollutant removal rates

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Other CWP Work of Interest
Small Watershed Restoration Manual
Series Maryland Watershed Users Guide Smart
Watershed Benchmarking Tool Urban Watershed
Forestry Manuals Wetland and Watersheds Articles

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The Small Watershed Restoration Manual Series
Check availability at www.cwp.org
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Manual 2. Methods to Develop Restoration Plans
for Small Urban Watersheds
Step-by-step guidance to develop, adopt and
implement restoration plans Features 32
different desktop analysis, field assessment,
stakeholder involvement and restoration
management methods Detailed info on plan scoping
and budgeting
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MD Watershed Users Guide

• Unified approach to watershed planning
• 27 key planning principles
• Step by step methods
• Costs and load reductions
• Over 20 planning tools

Get the latest version at http//dnr.maryl
and.gov/watersheds/pubs/userguide.html
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Smart Watershed Benchmarking Tool

• Developed to measure integration and activity of
  14 municipal watershed restoration programs
• 56 individual benchmark questions, total 100 pts
  (plus extra credit)
• Benchmarks based on survey of 50 communities
  across country
• Tested in 4 communities in 2005

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Download for free at www.cwp.org
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Download for free at www.cwp.org
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Catchment F (38.43 acres)
Monitoring Station
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Catchment O (38.7 acres)
Monitoring Station