Storm Water

Revisions to Massachusetts Stormwater Management Tetra Tech Rizzo Braintree Presentation Spring 2008

Stormwater Management Standard 1 1996/1997 Stormwater Management Standards

2008 The Stormwater Management Standards

The Department will presume that projects meeting the Stormwater Management Standards satisfy regulatory requirements. When one or more of the Standards cannot be met, an applicant may demonstrate that an equivalent level of environmental protection will be provided. 12. No new stormwater conveyances (e.g. outfalls) may discharge untreated stormwater directly to or cause erosion in wetlands or waters of the Commonwealth.

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1. No new stormwater conveyances (e.g. outfalls) may discharge untreated stormwater directly to or cause erosion in wetlands or waters of the Commonwealth.

Stormwater Management Standard 1-Summary  “The use of level spreaders or other techniques at the point of discharge is required to minimize erosion.”

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Stormwater Management Standard 2 1996/1997 2. Stormwater management systems must be designed so that post-development peak discharge rates do not exceed pre-development peak discharge rates.

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2008 2. Stormwater management systems shall be designed so that post-development peak discharge rates do not exceed pre-development peak discharge rates. This Standard may be waived for discharges to land subject to coastal storm flowage as defined in 310 CMR 10.04.

Stormwater Management Standard 2-Summary  “Where an area is within the 100-year coastal flood plain or land subject to coastal storm flowage, the control of peak discharge rates is usually unnecessary and may be waived.”  “…requires that the post development peak discharge rate is equal to or less than the pre-development rate from the 2-year and the 10-year 24-hour storms… Proponents must also evaluate the impact of peak discharges from the 100-year 24hour storm. If this evaluation shows that increased off-site flooding will result from peak discharges from the 100-year 24-hour storms, BMPs must also be provided to attenuate these discharges.”

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Stormwater Management Standard 3 1996/1997 3. Loss of annual recharge to groundwater should be minimized through the use of infiltration measures to the maximum extent practicable. The annual recharge from the post-development site should approximate the annual recharge from the pre-development or existing site conditions, based on soil types.[1] [1] “To the extent practicable” means the applicant has made all reasonable efforts to meet the standards, including evaluation of alternative BMP designs and their locations.

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2008 3. Loss of annual recharge to groundwater shall be eliminated or minimized through the use of infiltration measures including environmentally sensitive site design, low impact development techniques, stormwater best management practices, and good operation and maintenance. At a minimum, the annual recharge from the post-development site shall approximate the annual recharge from pre-development conditions based on soil type. This Standard is met when the stormwater management system is designed to infiltrate the required recharge volume as determined in accordance with the Massachusetts Stormwater Handbook.

Stormwater Management Standard 3-Summary  New recharge requirements: (For sites comprised solely of C and D soils and bedrock at the land surface, proponents are required to infiltrate the required volume only to the maximum extent practicable.) Hydrologic Group Volume to Recharge (x Total Impervious Area) Hydrologic Group A

Volume to Recharge x Total Impervious Area

B

0.35 inches

C

0.25 inches

D

0.10 inches

0.60 inches

 Pretreatment is required before discharge to an infiltration BMP.

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Stormwater Management Standard 3-Summary Con’t. Rules for Groundwater Recharge  All BMPs must be designed according to the specifications and procedures in Volumes 2 and 3 of the Massachusetts Stormwater Handbook.  Except as expressly provided herein, entire required recharge volume must be infiltrated.  Required recharge volume must be infiltrated only to the maximum extent practicable, if: • The site is comprised wholly of C and D soils and bedrock at the land surface; • Recharge is proposed at or adjacent to a site that has: • been classified as contaminated • Contamination that has been capped in place; • an Activity and Use Limitation (AUL) that precluded inducing runoff to the groundwater pursuant to MGL Chapter 21E and the Massachusetts Contingency Plan, 310 CMR 40.0000; • has a solid waste landfill as defined in 310 CMR 19.000;or • groundwater from the recharge area that flows directly toward a solid waste landfill or 21E site.

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Stormwater Management Standard 3-Summary Con’t. Rules for Groundwater Recharge-Con’t  Design Requirements: • At least 44% of the TSS must be removed prior to discharge to the infiltration structure if the discharge is: • within a Zone II or IWPA; • near an ORW or SRW; • near a shellfish growing area, cold water fisher, or bathing beach; • from a Land Use with Higher Potential Pollutant Loads (LUHPPLs); or • within an area with a rapid infiltration rate (greater than 2.4 inches per hour).

• Except as set forth below, roof runoff from metal roofs may be discharged to the ground via a dry well without pretreatment. The discharge of roof runoff to the ground requires pretreatment by means of a BMP capable of removing metals, such as sand filter, organic filter or filtering bioretention area, if the roof is a metal roof that is located in the Zone II or IWPA of a public water supply and/or at an industrial site. metal Roofs are galvanized steel or copper.

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Stormwater Management Standard 3-Summary Con’t. Rules for Groundwater Recharge-Con’t  Design Requirements-Con’t: • At a minimum there should be a two-foot separation between bottom of structure and seasonal high groundwater. • Minimum infiltration rate=0.17 inches per hour. • All infiltration structures must be able to drain fully within 72 hours. • General Setback Requirements • Title 5 SAS: 50 feet • Private wells: 100 feet • Public wells: outside Zone I • Public reservoir, surface water sources for public water systems and their tributaries: Outside Zone A • Other surface waters: 50 feet • Property Line: 10 feet

• Specific BMPs have additional setback requirements: See Vol. 2. Ch. 2

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Stormwater Management Standard 4 1996/1997

2008

4. For new development, stormwater management systems must be designed to remove 80% of the average annual load (post-development conditions) of Total Suspended Solids (TSS). It is presumed that this standard is met when:

4. Stormwater management systems shall be designed to remove 80% of the average annual post-construction load of Total Suspended Solids (TSS). This Standard is met when:

a. Suitable nonstructural practices for source control and pollution prevention are implemented;

a. Suitable practices for source control and pollution prevention are identified in a long-term pollution prevention plan, and thereafter are implemented and maintained;

b. Stormwater management best practices (BMPs) are sized to capture the prescribed runoff volume; and

b.

c. Stormwater management BMPs are maintained as designed.

Structural stormwater best management practices are sized to capture the required water quality volume determined in accordance with the Massachusetts Stormwater Handbook; and c. Pretreatment is provided in accordance with the Massachusetts Stormwater Handbook.

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Stormwater Management Standard 4-Summary  The required water quality volume equals 1 inch of runoff times the total impervious area of the post-development project site for a discharge: • from a LUHPPL; • within an area with a rapid infiltration rate (>2.4 inches per hour); • within 1 Zone II or IWPA; or • near or to the following critical areas • ORW • SRW • bathing beaches • shellfish growing areas • cold-water fisheries

 The required water quality volume equals 0.5 inches of runoff times the total impervious area of the post-development project site for all other discharges.  Development and implementation of suitable practices for source control and pollution prevention is required and identified in a long-term pollution prevention plan.  New TSS removal efficiencies and design requirements for BMPS

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TSS Removal Efficiencies for BMPs-Pretreatment BMP

TSS Removal Efficiency Non-Structural

Street Sweeping

0-10% (See Vol. 2, Ch. 1) Structural

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Deep Sump Catch Basins

25% (off-line and pretreatment)

Oil Grit Separator

25% (off-line and pretreatment)

Proprietary Separators

Varies (See Vol. 2, Ch. 4)

Sediment Forebays

25% (Pretreatment)

Vegetated Filter Strips

10% 25’W min, 45% 50’W min.

TSS Removal Efficiencies for BMPs-Treatment BMP

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TSS Removal Efficiency

Bioretention Areas

90% with pretreatment

Constructed Stormwater Wetlands

80% with sediment forebay

Extended Dry Detention Basins

50% with sediment forebay

Gravel Wetlands

80% with sediment forebay

Proprietary Media Filters

Varies (See Vol. 2, Ch. 4)

Sand/Organic Filters

80% with sediment forebay

Treebox Filter

80% with pretreatment

Wet Basins

80% with sediment forebay

TSS Removal Efficiencies for BMPs-Conveyance BMP Drainage Channels

TSS Removal Efficiency 0% (conveyance only)

Grass Channel (Biofilter Swales) 50% with sediment forebay or equal Water Quality Swale (Wet and Dry)

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70% with sediment forebay or equal

TSS Removal Efficiencies for BMPs-Infiltration1 BMP

TSS Removal Efficiency

Dry Wells

80% non-metal roofs anywhere or metal roofs not located in Zone II, IWPA or industrial site

Infiltration Basin or Trench

80% with sediment forebay, vegetated filter strip, grass channel or water quality swale

Leaching Catch Basins

80% with deep sump catch basin as pretreatment

Subsurface Structure

80% with pretreatment device

Currently all subsurface infiltration structures required Underground Injection Permit, some bioretention structures required permitting too 1

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TSS Removal Efficiencies for BMPs-Other Devises BMP

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TSS Removal Efficiency

Dry Detention Basins

0% Peak rate attenuation only

Green Roofs

0% water quality volume reduction possible (see Vol. 2 Ch. 2)

Porous Pavement

80% depends on design (only for uses in Vol. 2, Ch. 2)

Rain Barrels and Cisterns

0% water quality volume reduction possible

Stormwater Management Standard 5

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1996/1997

2008

5. Stormwater discharges from areas with higher potential pollutant loads require the use of specific stormwater management BMPs (see chart on page 18). The use of infiltration practices without pretreatment is prohibited.

5. For land uses with higher potential pollutant loads, source control and pollution prevention shall be implemented in accordance with the Massachusetts Stormwater Handbook to eliminate or reduce the discharge of stormwater runoff from such land uses to the maximum extent practicable. If through source control and/or pollution prevention all land uses with higher potential pollutant loads cannot be completely protected from exposure to rain, snow, snow melt, and stormwater runoff, the proponent shall use the specific structural stormwater BMPs determined by the Department to be suitable for such uses as provided in the Massachusetts Stormwater Handbook. Stormwater discharges from land uses with higher potential pollutant loads shall also comply with the requirements of the Massachusetts Clean Waters Act, M.G.L. c. 21, §§ 26-53 and the regulations promulgated thereunder at 314 CMR 3.00, 314 CMR 4.00 and 314 CMR 5.00.

Stormwater Management Standard 5-Summary  Eliminate or reduce discharge of stormwater runoff from LUHPPLs to the maximum extent practicable.  Best Management Practices for LUHPPLs • Discharges from certain LUHPPLs may be subject to additional requirment including the need to obtain an individual or general discharge permit pursuant to the MA clean Waters Act of Fedreal Clean Water Act. • All proponents must implement source control and pollution prevention. • All BMPs shall be designed in accordance with specifications and sizing methodologies in the Massachusetts Stormwater Handbook Volumes 2 and 3. • The required water quality volume equals 1 inch times the total impervious area of the postdevelopment site. • Many land uses have the potential to generate higher potential pollutant loads of oil and grease. These land uses include, without limitation, industrial machinery and equipment and railroad equipment maintenance, log storage and sorting yards, aircraft maintenance areas, railroad yards, fueling stations, vehicle maintenance and repair, construction businesses, paving, heavy equipment storage and/or maintenance, the storage of petroleum products, high-intensity-use parking lots1, and fleet storage areas. to treat the runoff from such land uses, the following BMPS must be used to pretreat the runoff prior to discharge to an infiltration structure: an oil grit separator, a sand filter, organic filter, filtering bioretention area, or equivalent. 1

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1000 vehicle trips per day or more. Shopping centers, malls, and large office parks typically have high-intensityuse parking lots.

Stormwater Management Standard 5-Summary  Best Management Practices for LUHPPLs-Con’t • At least 44%TSS removal is required prior to discharge to an infiltration device. • Until they complete the STEP or TARP verification process outlines in Volume 2, proprietary BMPs may not be used as a terminal treatment device for runoff from LUHPPLs. For purposes of this requirement, subsurface structures, even those that have a storage chamber that has been manufactured are not considered proprietary BMPS, since the treatment occurs in the soil below the structure, not in the structure.

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Stormwater Management Standard 6 1996/1997 6. Stormwater discharges to critical areas must utilize certain stormwater management BMPs approved for critical areas (see list of page 1-8). Critical areas are Outstanding Resource Waters (ORWs), shellfish beds, swimming beaches, cold water fisheries and recharge areas for public water supplies.

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2008 6. Stormwater discharges within the Zone II or Interim Wellhead Protection Area of a public water supply, and stormwater discharges near or to any other critical area, require the use of the specific source control and pollution prevention measures and the specific structural stormwater best management practices determined by the Department to be suitable for managing discharges to such areas, as provided in the Massachusetts Stormwater Handbook. A discharge is near a critical area if there is a strong likelihood of a significant impact occurring to said area, taking into account site-specific factors. Stormwater discharges to Outstanding Resource Waters and Special Resource Waters shall be removed and set back from the receiving water or wetland and receive the highest and best practical method of treatment. A “storm water discharge” as defined in 314 CMR 3.04(2)(a)1 or (b) to an Outstanding Resource Water or Special Resource Water shall comply with 314 CMR 3.00 and 314 CMR 4.00. Stormwater discharges to a Zone I or Zone A are prohibited unless essential to the operation of a public water supply.

Stormwater Management Standard 6-Summary  See charts in Vol. 1, Ch.1 for BMP selection for stormwater discharges to: • Zone II; • IWPA; • ORW (Vernal Pools, surface water sources for PWS); • SRW; • Bathing beaches; • Cold-water fisheries; • Shellfish growing areas; • Zone I (prohibited unless essential to operation of the water supply); and • Zone A (prohibited unless essential to operation of the water supply).

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Stormwater Management Standard 7 1996/1997 7. Redevelopment of previously developed sites must meet the Stormwater Management Standards to the maximum extent practicable. However, if it is not practicable to meet all the Standards, new (retrofitted or expanded) stormwater management systems must be designed to improve existing conditions.

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2008 7. A redevelopment project is required to meet the following Stormwater Management Standards only to the maximum extent practicable: Standard 2, Standard 3, and the pretreatment and structural best management practice requirements of Standards 4, 5, and 6. Existing stormwater discharges shall comply with Standard 1 only to the maximum extent practicable. A redevelopment project shall also comply with all other requirements of the Stormwater Management Standards and improve existing conditions.

Stormwater Management Standard 7-Summary  Clarification of Redevelopment Projects and requirements. (See Vol. 2, Ch. 3 for Redevelopment Projects Checklist) ALL REDEVELOPMENT PROJECTS MUST IMPROVE EXISTING CONDITIONS • Redevelopment Projects are defined to include the following: • Maintenance and improvement of existing roadways, including widening less than a single land, adding shoulders, correcting substandard intersections, improving drainage systems, and repaving; • Development, rehabilitation, expansion and phased projects on previously developed sites, provided the redevelopment results in no net increase in impervious area; and • Remedial projects specifically designed to provide improved stormwater management, such as projects to separate storm drains and sanitary sewers and stormwater retrofit projects.

• Redevelopment and new construction standards can apply to the same project (see Vol. 1, Ch. 1, page 22 for example)

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Stormwater Management Standard 8

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1996/1997

2008

8. Erosion and sediment controls must be implemented to prevent impacts during construction or land disturbance activities.

8. A plan to control construction-related impacts including erosion, sedimentation and other pollutant sources during construction and land disturbance activities (construction period erosion, sedimentation, and pollution prevention plan) shall be developed and implemented.

Stormwater Management Standard 8-Summary  Clarification of erosion and sedimentation control plan requirements. • A SWPPP can be used to satisfy Standard 8. • The following documents provide additional erosion and sediment control information: • MA Erosion & Sedimentation Control Guidelines http://mass.gov/dep/water/esfull.pdf • Nonpoint Source Manual (formally known as the MegaManual) http://projects.geosyntec.com/NPSManual

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Stormwater Management Standard 9

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1996/1997

2008

9. All stormwater management systems must have an operations and maintenance plan to ensure that systems function as designed.

9. A long-term operation and maintenance plan shall be developed and implemented to ensure that stormwater management systems function as designed.

Stormwater Management Standard 9-Summary  Clarification of Operation and Maintenance Plan requirements. • The Long-Term Operation and Maintenance Plan shall at a minimum include: • Stormwater management system(s) owners; • The party or parties responsible for operation and maintenance, including how future property owners will be notified of the presence of the stormwater management system and the requirement for proper operation and maintenance; • The routine and no-routine maintenance tasks to be undertaken after construction is complete and a schedule for implementing those tasks; • A plan that is drawn to scale and shows the location of all stormwater BMPs in each treatment train along with the discharge point; • A description and delineation of public safety features; and • An estimated operations and maintenance budget.

• Guidelines for Order of Conditions can be found in Vol. 1, Ch. 1.

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Stormwater Management Standard 10 1996/1997

2008 10. All illicit discharges to the stormwater management system are prohibited.

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Stormwater Management Standard 10-Summary  “Proponents of projects within Wetlands jurisdiction must demonstrate compliance with this requirement by submitting to the issuing authority an Illicit Discharge Compliance Statement verifying that no illicit discharges exist on the site and by including in the pollution prevention plan measures to prevent illicit discharges to the stormwater management system, including wastewater discharges and discharges of stormwater contaminated by contact with process wastes, raw materials, toxic pollutants, hazardous substances, oil, or grease.”  The Illicit Discharge Compliance Statement must be accompanied by a site map that is drawn to scale and that identifies the location of any systems for conveying stormwater on the site and shows that these systems do not allow the entry of any illicit discharges into the stormwater management system.

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Stormwater Management Standards Applicability 1996/1997 The Stormwater Management Standards apply to industrial, commercial, institutional, residential subdivision, and roadway projects, including site preparation, construction, redevelopment, and on-going operation.

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2008 Except as expressly provided herein, stormwater runoff from all industrial, commercial, institutional, office, residential and transportation projects including site preparation, construction and redevelopment, and all point source stormwater discharges from said projects shall be managed according to the Stormwater Management Standards.

Stormwater Management Standards Applicability 1996/1997

2008

The Stormwater Management Standards do not apply to: 5

The Stormwater Management Standards shall not apply to:

(1) Single-family house projects;

(1) A single-family house;

(2) Residential subdivisions with four or fewer lots, provided any discharge will not affect a critical area; or

(2) Housing development and redevelopment projects comprised of detached single-family dwellings on four or fewer lots provided that there are no stormwater discharges that may potentially affect a critical area;

(3) Emergency repairs to roads or their drainage systems.

(3) Multi-family housing development and redevelopment projects with four or fewer units, including condominiums, cooperatives, apartment buildings and townhouses, provided that there are no stormwater discharges that may potentially affect a critical area; and [5]-For projects of any size, direct discharges of untreated stormwater from pipes to wetlands or waters are not allowed. Erosion and sedimentation control during construction must be provided.

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(4) Emergency repairs to roads or their drainage systems.

Stormwater Management Standards Applicability 1996/1997

2008

The Stormwater Management Standards apply to the extent practicable to:

The Stormwater Management Standards shall apply to the maximum extent practicable to the following:

(1) Residential subdivisions with four or fewer lots with a discharge potentially affecting a critical area; and

(1) Housing and redevelopment projects comprised of detached single-family dwellings on four or fewer lots that have a stormwater discharge that may potentially affect a critical area;

(2) Five to nine residential lots, provided any discharge will not affect a critical area.

(2) Multi-family housing development and redevelopment projects, with four or fewer units, including condominiums, cooperatives, apartment buildings, and townhouses, that have a stormwater discharge that may potentially affect a critical area; (3) Housing development and redevelopment projects comprised of detached single-family dwellings on five to nine lots, provided there is no stormwater discharge that may potentially affect a critical area;

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Stormwater Management Standards Applicability 1996/1997

2008 Continued (4) Multi-family housing development and redevelopment projects with five to nine units, including condominiums, cooperatives, apartment buildings, and townhouse, provided there is no stormwater discharge that may potentially affect a critical area; (5) Marinas and boat yards, provided that the hull maintenance, painting and service areas are protected from exposure to rain, snow, snow melt, and stormwater runoff; and (6) Footpaths, bikepaths and other paths for pedestrian and/or no motorized vehicle access.

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Applicability Summary Land Use

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Industrial Uses

Apply Fully

Commercial Uses

Apply Fully

Institutional Uses

Apply Fully

Office Uses

Apply Fully

Residential Uses

See Residential Table and Exemptions

Transportation

See Exemptions, otherwise Apply Fully

Land Uses Not Specifically Exempted

Apply Fully

Applicability Summary-Con’t Residential Table General Rule

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>4 lots/units with discharge to critical area OR >10 lots or units

<4 lots/units with discahrge to critical area OR 5 to 9 lots/units with no discharge to critical area

Single Family Detached Dwellings

Apply Fully

Apply Maximum Extent Practicable

Multi-Family Dwellings

Apply Fully

Apply Maximum Extent Practicable

Marinas and Boat Yards

Apply Maximum Extent Practicable

Footpaths, bike paths and other “paths”

Apply Maximum Extent Practicable

Additional Considerations  Stormwater facilities after January 2, 2008: • Outside a wetland buffer: remains a BMP not a wetland-No Jurisdiction • Inside a wetland buffer: remains a BMP not a wetland-Jurisdiction for replacement or alteration • Wetlands expanding into or buffers expanding into BMPs: subject to wetlands regulations-Jurisdiction for replacement or alteration  Discharge to water body with a TMDL requires BMPs Specific for the limits  LID credits for “green” site design  New methods for recharge area sizing  New BMP specifications (Vol. 2, ch. 2)  New ways of handling proprietary BMPs (Vortechs, Downstream Defender, etc.)  New Stormwater Management Report requirements (Vol. 3, ch. 1, Checklist)

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Major changes  Street Sweeping TSS Credits Tss Removal Rate

High Efficiency Vacuum SweeperFrequency of Sweeping

Regenerative Air Sweeper-Frequency of Sweeping

Mechanical Sweeper (Rotary Broom)Frequency of Sweeping

10%

Monthly average, with sweeping primarily spring and fall

Every 2 weeks average, with sweeping primarily spring and fall

Weekly average, with sweeping primarily spring and fall

5%

Quarterly average, with sweeping primarily spring and fall

Quarterly average, with sweeping primarily spring and fall

Monthly average, with sweeping primarily spring and fall

0%

Less than above

Less than above

Less than above

 More focus on Erosion and Sediment Control Plan (Vol. 2. Ch.1)  More focus on Pollution Prevention Plan (Vol. 2. Ch.1)  More focus on Operations and Maintenance Plan (Vol. 2. Ch.1)  More focus on classifying BMP (Pretreatment, Treatment, Conveyance, Infiltration, Filtration, etc.) and selection process. (Vol. 2. Ch.1)

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Major Changes-Con’t.  Volume 2, Chapter 2:Structural BMP Specifications for the Massachusetts Stormwater Handbook

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Major Changes-con’t.  Revised and New BMPs • Vegetated Filter Strips • Bioretention Areas and Rain Gardens • Constructed Stormwater Wetlands (5 Types) •Shallow Marsh System

•Pocket Wetlands

•Basin/Wetlands System

•Gravel Wetlands

•Extended Detention Wetlands

• Extended Dry Detention Basin • Proprietary media Filters • Sand and Organic Filters (Tree Box Filter tucked into this category) • Wet Basins • Channels

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•Drainage Channel-0% TSS

•Water Quality Swale (Dry or Wet)-70% TSS*

•Grassed Channel (Biofilter Swale)-50% TSS*

*

w/pretreatment

Major Changes-Con’t • Revised and New BMPs-Con’t • Subsurface Structures • Dry Detention Basin-0% TSS • Green Roofs • Porous Pavement • Rain Barrels & Cisterns • BMP Accessories •Level Spreaders

•Check Dams

•Outlet Structures

•Catch Basin Inserts

• Checklist for Redevelopment Projects (See Volume 2, Chapter 3) • Extent of applicability of each standard • Retrofitting Existing BMPs • Specific Redevelopment Project Requirements (Groundwater Recharge Areas, Cold Water Fisheries, Brownfield Redevelopment, Runoff to Impaired Water Bodies (TMDLs), Runoff to Areas of Localized Flooding

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Major Changes-con’t Proprietary Stormwater BMPs-Two Ways to Approve or Deny the Use of a Proprietary Stormwater BMP

 1.

MassDEP has reviewed the performance of a technology as determined by TARP or STEP and assigned a TSS removal efficiency. •

If the conditions under which it is proposed to be used are similar to those in the performance testing, presume that the proprietary BMP achieves the assigned TSS removal rate.

•

Look at sizing, flow and site conditions

2.

Issuing Authority makes a case-by-case assessment of a specific proposed use of a proprietary technology at a particular site and assigns a TSS removal efficiency. •

Proponent must submit reports or studies showing effectiveness of BMP.

•

MassDEP strongly recommends using UMass Stormwater Technologies Clearinghouse database to ensure that reports and studies are of high quality ( http://www.mastep.net ).

•

Look at sizing, flow and site conditions.

•

For ultra-urban and constrained sites, proprietary BMPs may be the best choice.

Summary: Two ways of approval

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7.

Legacy STEP evaluation

8.

Case by case basis utilizing UMass database

Major Changes-con’t-BMP Evaluation Programs  STEP-Massachusetts Strategic Envirotechnology Partnership (ended 2003) • http://www.mass.gov/envir/lean_green/documents/factsheets.htm • http://www.mass.gov/envir/lean_green/documents/techassessments.htm The only TSS STEP Approvals (legacy) • Stormceptor - 52 to 77% TSS • StormTreat - 80% TSS • Vortechnics – 60-83% TSS

 TARP-Technology Acceptance and Reciprocity Partnership • http://www.dep.state.pa.us/dep/deputate/pollprev/techservices/tarp/ • Clearing house kept at: http://www.mastep.net/ • Provides test results and evaluation of testing procedures (confidence level of test results)

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Major Changes-con’t -MASTEP Data-Searchable Database

Additional Information

•http:// www.epa.gov/ne/assistance/ceitts/stormwater/techs.ht •http://www.njcat.org/verification/verifications.cfm •http://www.unh.edu/erg/cstev •http://www.bmpdatabase.org/

•http://www.mass.gov/dep/water/wastewater/stormwat. •http://nemo.uconn.edu/tools/stormwater/ •http://www.cwp.org/

0-Unrated,1-Sufficient data, 2-Sound studies, 3-Some studies, 4-Insufficient data 44

Major Changes-con’t-MASTEP DATA-TSS Removal Devices

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Major Changes-con’t  Miscellaneous Stormwater Topics (see Volume 2, Chapter 5) • Mosquito Control • The Mosquito Control Board: http://www.mass.gov/agr/mosquito • Construction BMPs • Post-construction BMPs

• Roads and Stormwater BMPs • Narrow pavement • Disconnected runoff (country drainage, no curbs)

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Documenting Compliance  Volume 3, Chapter 1 outlines required computations for each Standard • Standard 1-No Untreated Discharges or Erosion to Wetlands • Calculate discahrge velocity at each outlet. • Reduce velocity to prevent erosion and scouring.

• Standard 2-Peak Rate Attenuation • Peak discharge for 2, 10 year storms • No downstream flooding 100 year storms • See Hydrology Handbook for Conservation Commissioners: http://www.mass.gov/dep/water/laws/hydrol.pdf

• Standard 3-Stormwater Recharge • Impervious Area (capture area adjustments for disconnected areas) • Required Recharge Volume (new depth chart) • Bottom Area Sizing for Infiltration Structures (major changes in these calculations) • Modeling methods • Rawl’s rate or in-situ saturated hydraulic conductivity

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Documenting Compliance-Con’t • Standard 4-Water Quality • Required Water Quality Volume (LUHPPLs, Critical Areas, etc.) • TSS removal rate (new TSS removal ratings, new TSS spreadsheet) • Weight determination (De Minimis discharges from individual outlets)

• Standard 5-Land Uses with higher Potential Pollutant Loads • BMPs selection • Source controls in Long-Term Pollution Prevention Plan

• Standard 6-Critical Areas • BMPs selection • Source controls in Long-Term Pollution Prevention Plan

• Standard 7-Redvelopment • Redevelopment Checklist-Volume 2, Chapter 3

• Standard 8-Construction Period Controls • Disturbed Area • Computations demonstrating that proposed control measures are properly sized

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Documenting Compliance-Con’t • Standard 9-Operation and Maintenance • Submit Operation and Maintenance Plan

• Standard 10-Illicit Discharges to Drainage System • Measures to prevent illicit discharges must be included in Pollution Prevention Plan • Illicit Discharge Compliance Statement must be submitted

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Documenting Compliance-Con’t  Low Impact Development Site Design Credits • Credit 1-Environmentally Sensitive Design • Cluster development, reduced scale=relief from Standard 3&4 (recharge and WQ) if all conditions are met. (See Volume 3, Chapter 1)

• Credit 2-Rooftop Runoff directed to Qualifying Pervious Area • Rooftop area omitted from impervious area total for the site if all conditions are met. (See Volume 3, Chapter 1)

• Credit 3-Roadway, Driveway or Parking Lot Runoff directed to Qualifying Pervious Area • Disconnected impervious areas can be subtracted from the site impervious area total if all conditions are met. (See Volume 3, Chapter 1)

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Documenting Compliance-Con’t  Stormwater Report • Stormwater Checklist stamped by Registered Professional Engineer • Narrative • Long-Term Pollution Prevention Plan • Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan • Operation and Maintenance Plan

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Recharge Requirements  Higher volumes required-new depth table  Minimum infiltration rate 0.17 in/hr • Rawls’ rate for Static or Simple Dynamic methods • 50% in-situ saturated hydraulic conductivity rate for Dynamic Field method

 Rapid Infiltration Rate is >2.4 in/hr • Rawls’ rate for Static or Simple Dynamic methods • 50% in-situ saturated hydraulic conductivity rate for Dynamic Field method

 44% TSS pretreatment for infiltration structures when • Rapid infiltration rate • LUHPPL • Critical Area

 80% TSS pretreatment for infiltration structures when • Dynamic Field method used for sizing

 72 Hour drawdown maximum  Mounding Analysis required if system bottom is within 4 feet of SHGW and proposed to attenuate 10 year storm or higher OR if site is adjacent to contaminated site

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Recharge Requirements-Con’t  Soil Evaluation • Review soil survey-whole site HSG evaluation • Site visit-whole site HSG evaluation • Test Pits-whole site HSG evaluation • Site conditions at recharge location determined • Soil textural analysis • Seasonal High Groundwater • Saturated Hydraulic Conductivity for Dynamic Field modeling else use Rawl’s • Hydraulic Conductivity tests (see BMPS Chapter for number of tests) • Guelph permeameter • Falling head permeameter • Double ring permeameter or infiltrometer • Amoozemeter or Amoozegar permeameter • NO TITLE 5 PERC TESTS

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