Stormwater By-laws Getting Town Buy-in & Approval Nora - - PowerPoint PPT Presentation

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Stormwater By-laws Getting Town Buy-in & Approval Nora - - PowerPoint PPT Presentation

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Stormwater By-laws Getting Town Buy-in & Approval Nora Loughnane Recharging First One Inch Runoff Phil Paradis Implementing Westwood Stormwater By-law Karon Skinner Catrone Workshop Presentation December 9, 2015 Stormwater

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SLIDE 1

Stormwater By-laws

  • Getting Town Buy-in & Approval

Nora Loughnane

  • Recharging First One Inch Runoff

Phil Paradis

  • Implementing Westwood Stormwater By-law

Karon Skinner Catrone

Workshop Presentation December 9, 2015

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SLIDE 2

Stormwater By-laws

  • Getting Town Buy-in & Approval of

Westwood’s New Stormwater Bylaw Nora Loughnane Director of Economic Development, Town of Westwood

Workshop Presentation December 9, 2015

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SLIDE 3

Stormwater Management Bylaw Adoption Formed Stormwater Committee

Town Engineer Building Commissioner Town Planner Conservation Agent

Engaged Phil Paradis of BETA Group, Inc. Reviewed current drainage systems. Consulted with NepRWA. Discussed mandate, goals, strategies, and limitations.

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SLIDE 4

Stormwater Management in New Development and Redevelopment

(Post Construction Stormwater Management)

  • Objective: To reduce the discharge of pollutants found in

stormwater through the retention or treatment of stormwater after construction on new or redeveloped sites.

  • a. Permittees shall develop, implement, and enforce a

program to address post-construction stormwater runoff from all new development and redevelopment projects that disturb one or more acres and discharge into the permittees MS4 at a minimum.

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SLIDE 5

Current Drainage Systems

  • No Treatment of Runoff
  • Direct Discharge of Pollutants to Water
  • Degrade Water Resources Every Event
  • Do not meet current Stormwater

Management Requirements

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SLIDE 6

Thresholds Higher than Minimum

70% to Neponset River impaired for:

 TSS, Turbidity, E. coli, Dissolved Oxygen,

Sedimentation/Siltation, PCB in fish, DDT

  • 30% to Charles River impaired for:

 Phosphorus (TMDL), E. coli, Nutrients, PCB in

fish, DDT & others

  • DWWD Wells – Westwood Water Supply
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SLIDE 7

Established Permit Thresholds

No Permit Required if

<5,000 sq. ft. of disturbance

Administrative Land Disturbance Permit

>5,000 sq. ft. but <21,780

Land Disturbance Permit

>21,780 and not otherwise subject to ConCom review

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SLIDE 8

Multiple Public Presentations

Westwood Planning Board Conservation Commission Board of Selectmen Finance & Warrant Commission

Focused on “Why?” Explained mandate. Emphasized shared responsibility, cost effectiveness, and efficiency of process. Provided concrete examples.

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SLIDE 9

Stormwater Management

  • Should I care?
  • What’s all the fuss?
  • Are there problems now?
  • Another permit?
  • Why should I pay?
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SLIDE 10

Development/Stormwater Impacts to Water Quality

Development Reduce Vegetation

Reduce Natural Treatment

Degraded Water Increase Runoff Increase Impervious

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SLIDE 11

Understand the Reality

Stormwater Runoff Includes

  • Sand & salt for winter snow/ice treatment
  • Soil from un-stabilized areas
  • Twigs, leaves and mulch
  • Cigarette butts, wrappers and other trash
  • Petroleum & metals from cars and trucks
  • Fertilizers from yards/lawns
  • Detergents from car washing
  • Fecal matter from pets & birds
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SLIDE 12

Water Quality

Without BMPs, everything that can be suspended or conveyed in stormwater runoff ends up in water resource systems (wetlands, lakes, rivers and ocean).

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SLIDE 13

Example 1 Modest Single Family Home

  • 30’x50’ House

= 1500± sq. ft.

  • 12’x40’ Driveway

= 500± sq. ft.

  • 30’x20’ Front Yard

= 600± sq. ft.

  • 30’x50’ Rear Yard

= 1500± sq. ft.

  • 30’x10’ Side Yards (2) = 600± sq. ft.
  • Total Disturbed Area

= 4700± sq. ft.

  • <5,000 sq. ft. = No Permit Required
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SLIDE 14

Example 2 Larger Single Family Home

  • 40’x50’ House

= 2,000± sq. ft.

  • 12’x60’ Driveway

= 700± sq. ft.

  • 50’x30’ Front Yard

= 1,500± sq. ft.

  • 60’x100’ Rear w/ Pool = 6,000± sq. ft.
  • 40’x25’ Side Yards (2) = 2,000± sq. ft.
  • Total Disturbed Area

= 12,200± sq. ft.

  • >5,000 sq. ft. but <21,780 =
  • Administrative Permit Required
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SLIDE 15

Town Meeting Article

Favorable recommendations from:

Westwood Planning Board Conservation Commission Board of Selectmen Finance & Warrant Commission

Presentation in cue. Not needed. Minimal discussion.

Unanimous vote for adoption !

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SLIDE 16

Stormwater By-laws

  • Recharging First One Inch Runoff

Phil Paradis, PE, LEADAP, CPSWQ BETA Group, Inc.

Consultant to Town of Westwood

Workshop Presentation December 9, 2015

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SLIDE 17

New Stormwater Technology

  • Magical Environmentally

Sensitive Solution

  • (MESS)

Patent Pending

(Not really)

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SLIDE 18

MESS – Solution For All Projects

  • Areas: Urban, Suburban, Rural & Campsite Areas
  • Uses: Agriculture, Residential, Commercial, Industrial,

Institutional, DPW Yards & Nuclear Facilities

  • Works with Terrain and Topography
  • Compatible with all Wetland, Riverfront, ACEC, NHESP,

FEMA, Chapter 91 and FDA Regulations

  • Abutters: Love it - produces no noise, odors or taxes
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SLIDE 19

MESS – SW Solution For Project

  • Requires no Space & Fits All Size Sites
  • Attenuates Peak Runoff for 2, 10, 100 & Armageddon

Year Storm Events

  • Accommodates All Soils (A-D & Bedrock)
  • Recharges first 7 inches of rainfall without flooding

adjacent basements

  • Groundwater Considerations: not necessary
  • Perfect Retrofit for Redevelopments
  • Maintenance can be performed via email
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SLIDE 20

Unfortunately

For Stormwater Engineers & Regulators there is no

Magical Environmentally Sensitive Solution

But an ever increasing challenge to address Stormwater Impacts for Past, Present and Future Development Projects

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SLIDE 21

Stormwater Management in New Development and Redevelopment

(Post Construction Stormwater Management)

  • 2.3.6.a.ii.(a)Stormwater management systems on new and

re-developed sites shall be designed to either:

  • Retain the first one (1) inch of runoff from all

impervious surfaces on site. OR

  • Provide the level of pollutant removal equal to or greater

than the level of pollutant removal provided through the use of biofiltration on the first one (1) inch of runoff from all impervious surfaces on site. This standard shall be met through a

combination of practices designed to retain runoff on site (environmentally sensitive site design, low impact development techniques) where technically feasible, and stormwater BMPs designed to treat the remainder of runoff that cannot be retained on site due to site constraints.

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SLIDE 22

To Retain 1 Inch SMP Must Consider

  • Development Area & Uses
  • Site Topography
  • Applicable Regulations
  • Impacts to Abutters
  • Available Space & Site Size
  • Peak Runoff impacts
  • Connected & Disconnected Impervious Area
  • Suitability of Soils & Groundwater Elev. for Recharge
  • Retrofit for Redevelopments
  • Ease of Inspection and Maintenance
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SLIDE 23

To Retain 1 Inch SMP Must Consider

  • Best Management Practice (BMP) or Low

Impact Development (LID) Technique $Costs:

 Design and Permitting  Installation  Operation and Maintenance

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SLIDE 24

Infiltration is as close to MESS as it comes

  • Reduces Runoff (Peak Rate & Volume)
  • Promotes Groundwater Percolation
  • Treats Runoff (Nutrients & Pathogens)
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SLIDE 25

Is Site Suitable for Recharge?

Determine Characteristics of On-site Soils

  • A - high infiltration rates, well/excessively well-drained sands/gravels.
  • B - moderate infiltration rates, moderately well/well drained soils.
  • C - slow infiltration rates, less draining soils.
  • D - very slow infiltration rates, poorly draining soils

Determine Seasonal High Groundwater Elevation

  • Typically 2 ft Separation required BMP bottom to SHGWE
  • Mounding Calculation may be required

Consider Other Factors

  • Abutter Impacts
  • Soil Contamination
  • Wellhead Protection Zone
  • Environmentally Sensitive Areas
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SLIDE 26

Typical BMPs for Sites > 1 Acres

Infiltration Systems

  • Retention/Infiltration Basin
  • Extended Dry Detention Basin
  • Subsurface Infiltration System
  • Infiltration Trench
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SLIDE 27

Typical BMPs for Sites > 1 Acres

Wetland/Treatment Systems

  • Constructed Stormwater Wetland
  • Water Quality Swale Wet/Dry
  • Bioretention Basin (Rain Garden)
  • Gravel Wetland
  • Wet Basin
  • Sand or Organic Filter
  • Proprietary Media Filter
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SLIDE 28

For Sites < 1 Acres

Low Impact Development (LID) Techniques

Disconnect Impervious Area, Address Runoff at Source & Small Recharge Areas Spread Throughout Site

Commercial Lot Techniques

  • Porous parking areas
  • Rain Gardens as landscaping features
  • Curb cuts
  • Drywells for roof runoff
  • Tree Box Filters
  • Green Roofs

Residential Lot Techniques

  • Porous driveways or
  • Slope driveways to lawn
  • Rain gardens at low areas
  • Maintain existing treeline
  • Rain barrels and drywells
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SLIDE 29

Commonwealth Ave Boston (~1.1 mile)

Stormwater Management Challenges

  • Required to Meet TMDL for Charles River
  • No Available Land Outside Right of Way

for BMPs

  • Significant Utilities in Road/ROW
  • Limited Outlet Connections
  • Recharge 1 inch Reduced to 65%

Phosphorus Removal (0.3 inch per soils)

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SLIDE 30

Commonwealth Ave Boston

Design Incorporated Retrofitting Existing System

  • Leaching Catchbasins
  • Leaching Manholes
  • Leaching Chambers
  • Leaching Pipe (Trench) Systems
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SLIDE 31

Commonwealth Ave Boston

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SLIDE 32

Commonwealth Ave Boston

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SLIDE 33

Pine Street Natick (~1 mile)

Stormwater Management Challenges

  • Non-existent/Undersized Drainage System
  • Existing Flooding Problems
  • Adding Impervious (5.5’ New Sidewalk)
  • Adding Curb
  • No Available Land Outside Right of Way

for BMPs

  • Limited Outlet Connections
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SLIDE 34

Pine Street Natick

Design Incorporated

  • Improved Country Drainage (removed

sediment berms)

  • LID Sidewalk – Sloped Away from Road
  • Sidewalk Sluice – to Maintain Country

Drainage

  • Water Quality Swale
  • Leaching Basin and Pipe Systems
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SLIDE 35

Pine Street Natick

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SLIDE 36

Pine Street Natick

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SLIDE 37
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SLIDE 38

Stormwater By-laws

  • Implementing Westwood Stormwater By-law

Karon Skinner Catrone Conservation Agent, Town of Westwood

Workshop Presentation December 9, 2015

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SLIDE 39

Westwood Stormwater Management Bylaw & Regulations

  • Projects that include Land Disturbance:
  • >5,000 sq. ft. but <1/2 acres

 Administrative Land Disturbance Permit

  • >1/2 acre & Special Circumstances

 Land Disturbance Permit

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SLIDE 40

Administrative Land Disturbance Permit

  • Submission

 Application, Narrative, Plan, Fee

  • Basic Controls

 Grade driveways not to drain to street  Recharge new roof runoff  Erosion controls

  • Review by SW Authority (Town Staff)

 Approx. one week review time  Obtain 1 Page Approval with Conditions

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SLIDE 41

Land Disturbance Permit

  • Submission

 Application, Narrative, Plan, Fee, SW Plan,

EC Plan, O&M Plan & supporting Calculations

  • Controls

 LID & BMPs to manage runoff and WQ  Meet Stormwater Management Standards

  • Review by SW Authority (Conservation)

 Public Hearing Process  Approx. one month review time  Obtain Approval with Conditions

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SLIDE 42

Stormwater By-laws

Questions and Discussion

Workshop Presentation December 9, 2015