Non-profit 501(c)3, non-advocacy organization


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Non-profit 501(c)3, non-advocacy organization

  • 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



UMBC (Engineering, CUERE)

  • UMBC (Engineering, CUERE)

  • City of Baltimore, DPW

  • Baltimore County, DEPRM

  • USDA Forest Service, Baltimore Ecosystem Study



Purpose of the study

  • Purpose of the study

  • Nature of the study area

  • Project study tasks

  • Initial pollutant removal rates

  • Findings from Chesapeake Bay survey

  • Other CWP resources



Muncipalities are sweeping and cleaning storm drains – can it make a difference in reducing nutrient loads to Bay?

  • 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













Task 1: Literature Review and Reference Tracking

  • 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



Street Sweeping Treatments

  • Street Sweeping Treatments



  • Catchment F

  • Treatment #1 = moderate street sweeping effort (status quo)

  • Treatment #2 = 85% reduction in curb miles swept.



4 treatment street sections

  • 4 treatment street sections

  • 2 controls street sections

  • 3 samples types



100 accumulation samples

    • 100 accumulation samples


Total 100 accumulation samples

  • Total 100 accumulation samples

  • Subset 16 for chemical analyses

    • TSS, TS
    • TKN, NO2+NO3
    • TP, PO4
    • BOD, COD
    • Total Cu, Pb, Zn, Cd


75 monitoring and modeling studies were reviewed from the 1970s to present

  • 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



Only a handful of studies monitored the pollutant reduction and the optimal frequencies for cleanouts at a catchment scale.

  • 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).



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

  • 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





Discounted for:

  • Discounted for:

    • Solubility
    • Washoff & fugitive dust loss
    • Runon*
    • Frequency
    • Technology*
    • Parked cars
    • Street conditions


Discounted for



4 sections

  • 4 sections

  • 43 questions

    • Community condition
    • Street Sweeping practice
    • Stormdrain maintenance
    • Monitoring
  • 73% response rate



  • $14.75 to $75/curb mile

  • 85% of Phase I and II communities sweep more frequently than annually (17)

  • How frequent?







Of 20 responses,

  • Of 20 responses,

    • 8 regular schedule cleanouts
    • 12 response to complaints or clogging
  • $1.39/linear ft; ~$55/catchbasin





Review Requested on Memos 1 & 2

  • 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








Unified approach to watershed planning

  • Unified approach to watershed planning

  • 27 key planning principles

  • Step by step methods

  • Costs and load reductions

  • Over 20 planning tools














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