City of San Antonio Department of Public Works Storm Water Division

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City of San AntonioDepartment of Public
WorksStorm Water Division

• Storm Water Program
• Richard Mendoza, P.E.
• Assistant Director of Public Works

May 29, 2009
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Storm Water Management Programs

• National Pollutant Discharge Elimination System
  (NPDES) Permit
• Texas Pollutant Discharge Elimination System
  Permit (TPDES)
• Municipal Separate Storm Sewer System (MS4)
• National Flood Insurance Program (NFIP)

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Current Storm Water Programs

• Open Waterway Maintenance
• Surface Maintenance
• Capital Projects Review
• Floodplain Management

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Funding

• Maintenance, operations, and capital
  infrastructure improvements are funded through a
  Storm Water Utility Fee collected in the monthly
  utility bill (either water or electric)
• Regional Storm Water Facilities Management
  Program

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Fee In Lieu Of (FILO)

• Nonresidential Minimum Fee
• Nonresidential with less than 65 impervious
  cover
• 2,600 per acre
• Nonresidential with impervious cover of 65 or
  greater
• 3,000 per acre

• Residential Minimum Fee
• Detached single family and two-family duplex
  Residential developments
• 1200 per acre or 750 per lot, whichever is less
• Residential development other than single family
  or two family
• 1600 per acre

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Regional Fund Balance

• FY 2009 Beginning Fund Balance
• 18,644,389.00
• FY 2009 Appropriations
• 12,133,518.00
• Gross End Balance
• 6,510,871.00

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Bexar Regional Watershed Management (BRWM)

• Partnership between City, Bexar County, San
  Antonio River Authority, and Suburban Cities
• The purpose of the BRWM is to address water
  quality and quantity issues collaboratively
  rather than individually

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Floodplain Management

• Robert Browning, PE, CFM
• Chief Storm Water Engineer

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Storm Water Engineering Division Responsibilities

• Regulate compliance with NFIP, Texas, and CoSA
  storm water management rules and regulations
• Manage SW Infrastructure
• Citizen Concern Investigation
• Capital Improvement Project Review
• Master Planning
• In House Design
• Protect Floodplains
• Flood Insurance Rate Map revisions
• Coordinate Floodplain violation enforcement and
  mitigation

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Storm Water Engineering Division Responsibilities

• Protect Public Safety
• Private Development Review
• Adverse Impact Analyses
• Regional Storm Water Management Program
  Participation Requests

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San Antonio Unified Development Code

• 35-504(b)(1) Regional SWM Program
• The city of San Antonio has determined that
  regional storm water management is preferable to
  site specific storm water mitigation. The
  regional storm water management program allows
  developers to participate in the program rather
  than constructing the on-site detention controls
  required by this Section where there will be no
  adverse impact.

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SWE Team Breakdown
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San Antonio Unified Development Code

• 35-504(b)(6)(7)
• Peak storm water runoff rates from all
  development shall be less than or equal to the
  peak runoff rates from the site's predevelopment
  conditions for the 5-year, 25-year and 100-year
  design storm events, except as provided in
  35-504(b)(1), above.
• Summary
• Developers dont have to fix problems but they
  cant make them worse.

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San Antonio Unified Development Code

• 35-504 Storm Water Management
• The purpose of this section is to provide
  adequate measures for the retention, detention
  and distribution of storm water in a manner that
  minimizes the possibility of adverse impacts on
  both water quantity and water quality during
  development. Innovative runoff management
  practices designed to meet the provisions of the
  UDC, enhance the recharge of groundwater, and
  maintain the function of critical environmental
  features are encouraged.

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Low Impact Development Options

• BioRetention / Bioswales
• Pro
• Extended runoff time.
• Increased percolation encourages base flow
• Attractive
• Con
• Difficult to predict / model detention effect

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Low Impact Development Options

• Rainwater Harvesting
• Pros
• Re-use (Reduced Water Bills)
• Can be attractive
• Above Ground Less Expensive
• Easy to create hybrid system
• Easy to calculate impact
• Con
• More expensive to make attractive

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Low Impact Development Options

• Rainwater Harvesting

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Low Impact Development Options

• Multi-Use Facilities
• (Park and Detention Pond)
• Pro
• Multi-Uses more bang for the buck
• Con
• Takes Land

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Low Impact Development Conclusion

• Low Impact Development Practices can help
  decrease peak runoff volumes.
• flow reduction impact must be agreed upon.
• Use can reduce impact of development on
  maintenance budget.
• Maintenance and other issues make modeling
  impacts difficult.
• Hybrid systems, are best option.
• combine water quantity reduction and water
  quality protection measures.

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Storm Water Operations

• Dennis Scott
• Operations Manager

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Open Waterway Maintenance

• Storm sewer maintenance
• Maintenance in federally mandated channels
• Natural waterway maintenance
• Lake de-silting operations
• Earthen and concrete channel maintenance
• Vegetation Control

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Surface Maintenance

• Arterial/collector/residential street cleaning
• Central Business District (CBD) cleaning
• Median maintenance
• Operation and Maintenance of Tunnels, Dams

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TPDES Compliance

• Street Cleaning
• River Maintenance
• Natural waterways and designed channels are
  inspected on regular basis for debris removal
• Vegetation Maintenance
• Mowing drainage channels and right-of-ways.

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TPDES, cont.

• Fire, Haz Mat Spill Response
• Household Hazardous Waste
• Testing/Monitoring (SAWS)
• Public Education (Schools, Community Events)
• Increase public awareness of pollution prevention
  strategies
• Conservation measures
• Promote water quality

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MS4 Compliance

• Storm Water Operations Division is responsible
  for repairs and daily maintenance of the existing
  system
• Daily Maintenance includes
• Grading Channels
• Erosion Control
• Concrete Repair
• Facility Cleaning (Inlets, Pipes, Culverts)
• Vegetation Control
• Street Sweeping
• Sediment Removal

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Infrastructure Management Plan (IMP)

• 5-Year Rolling Program that addresses
  infrastructure maintenance throughout the City
• Involves drainage maintenance and debris removal

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Vegetation Maintenance

• Consists of mowing drainage channels and
  easements along the channels

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Fiscal Year 2008

• The Natural Creek Crew maintained a total of 45
  miles of natural creekways.
• Mowing Crews completed 3,772 acres of ROW mowing.
• Mowing crews also completed 12,926 acres of
  channel mowing.

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River Maintenance

• Natural waterways and designed channels are
  inspected on a regular basis for debris removal

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Facts and Figures

• Storm Water Operations Maintains
• 250 miles of Earthen Drainage Channels
• 140 miles of Concrete Drainage Channels
• 470 acres of Federally Mandated Channels
• 1,189 acres of Street Rights of Way Drainage
  Channels
• 156 acres of Medians Drainage Channels
• 74 acres of Flood Buyout Properties Drainage
  Channels
• 498 miles of Underground Storm Sewers Drainage
  Channels

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Street Cleaning

• Streets are swept on a planned schedule in order
  to prevent debris build up on curbs

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Cont.

• Storm Water Street Cleaning section completed in
  Fiscal Year 2008
• 8,393 gutter miles of Arterials and Collector
  Streets
• 16,001 gutter miles Residential Streets
• 21,720 gutter miles of Central Business District
  (CBD) Streets
• 448 Gutter miles of Fiesta Streets

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Fiscal Year 2008

• Storm Water Street Cleaning Section
• 9,902 sq. ft of Sidewalk Gum Removal
• 23,451 sq. ft of Sidewalk Soda Blasting
• Total sq. ft. of sidewalk cleaned 33,353

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Tunnel Maintenance

• Maintain and Operate 2 Tunnel Systems and 4 Dam
  Structures
• Maintain and Operate the High Water Detection
  System

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Tunnel Locations
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San Antonio River Tunnel

• Construction began in 1993 and was completed in
  December 1997
• Cost 111.4 Million
• Diameter 24 ft 4 in
• Depth to invert 150 feet
• Length 16,300 feet

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Annual River Cleaning

• Coordinated effort between Public Works, Downtown
  Operations, San Antonio River Authority, San
  Antonio Water System
• The River Walk is drained every year in January
  for cleaning
• During this time debris and sediment are removed
  by Storm Water Operations
• Crews removed an estimated 950 cubic yards of
  silt during the 2009 cleaning

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Water Quality

• Alberto Passos

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Annual Outfall Campaign

• During the annual cleaning SAWS collects samples
  of flowing outfalls into the River Walk for
  laboratory analysis
• Smoke testing is also performed to determine
  sources of outfalls
• Outfalls are numbered, located and photographed
  for GIS mapping purposes

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Annual Outfall Campaign Smoke Testing
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Annual Outfall Campaign Outfall Pictures
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River Walk Flow Augmentation (Water Quality Model
and Engineering Design)

• Assess the potential benefits to water quality in
  the River Walk of bringing additional external
  flow and increased flow circulation
• Developing a water quality model for this
  purpose.
• The model will also assess the potential benefit
  of the application of storm water pollution
  control measures (BMPs, LIDs) and of a dedicated
  water treatment system

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River Walk Flow Augmentation (Cont)

• This model will complement and refine the water
  quality modeling work developed for SARA (James
  Miertschen Associates).
• Model calibration and testing will utilize
  existing water quality data gathered by SAWS
  during River Walk outfall campaigns and
  additional sampling and analysis
• The model will be used to test different
  alternatives of improving quality the scope also
  includes the design of selected alternatives

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River Loop Sediment Reduction

• Objective to reduce turbidity and improve water
  clarity to reduce sources of nutrients and
  bacteria
• Initially, an outside contractor will be hired to
  remove approximately 5,000 cubic yards of
  sediments in the River Loop and Extension
• 1 to 2ft of sediment will be removed in the River
  Loop as much as possible from the Extension
• In the future Storm Water Operations may assume
  responsibility for this task

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Zoo Outfall UV Disinfection

• The bacteria load in the Zoo Outfall is a
  significant fraction (gt6) of the total load to
  the San Antonio River
• A Water Treatment Plant will be installed using
  Ultraviolet (UV) Disinfection to remove an
  estimated 99.9 of the bacteria
• Hippos have been relocated from directly in the
  outfall to a new habitat that does not flow into
  the outfall
• Klotz Associates are the contractors for this
  project

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Questions ?