Southborough Public Safety Complex · 2017. 12. 6. · OPERATION & MAINTENANCE PLAN Southborough...

OPERATION & MAINTENANCE PLAN

Southborough Public Safety

Complex 32 Cordaville Road

Southborough, Massachusetts

Prepared for Town of Southborough

17 Common Street Southborough, MA 01772

Prepared by Howard Stein Hudson

11 Beacon Street, Suite 1010 Boston, MA 02108

617-482-7080

November 3, 2017

Revised December 1, 2017

OPERATION & MAINTENANCE PLAN Town of Southborough Public Safety Complex

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Table of Contents Table of Contents ........................................................................................................................................... i

Project Narrative ........................................................................................................................................... 1

1.0 Introduction ........................................................................................................................................ 1

2.0 Purpose ............................................................................................................................................... 1

3.0 Descriptions and Locations of Stormwater BMPs ......................................................................... 1

3.1 Deep Sump Catch Basins ........................................................................................................................... 2

3.2 Stone Check Dams ....................................................................................................................................... 2

3.3 Sediment Forebay ........................................................................................................................................ 2

3.4 Infiltration Basin ......................................................................................................................................... 2

3.5 Water Quality Unit ...................................................................................................................................... 2

3.6 Outlet Control Structure ............................................................................................................................ 2

3.7 Rain Garden .................................................................................................................................................. 2

3.8 Water Quality Swale .................................................................................................................................... 2

3.9 Grassed Swales ............................................................................................................................................. 3

4.0 Inspection Frequency, Inspection Safety and Maintenance Safety ............................................. 3

4.1 Inspection Frequency ................................................................................................................................. 3

4.2 Inspection Safety ......................................................................................................................................... 3

4.2 maintenance Safety ..................................................................................................................................... 4

5.0 Inspection and Maintenance Procedures ........................................................................................ 4

5.1 Deep Sump Catch basins ............................................................................................................................ 5


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5.2 Stone Check Dams ....................................................................................................................................... 5

5.3 Sediment Forebay ........................................................................................................................................ 5

5.4 Infiltration Basin ......................................................................................................................................... 5

5.5 Water Quality Unit ...................................................................................................................................... 5

5.6 Outlet Control Structure ............................................................................................................................ 5

5.7 Rain Garden .................................................................................................................................................. 6

5.8 Water Quality Swale .................................................................................................................................... 6

5.9 Grassed Swales ............................................................................................................................................. 6

6.0 Record Keeping ................................................................................................................................. 6

7.0 Maintenance Responsibilities and Costs ........................................................................................ 6

Attachment A: Operation and Maintenance Agreement .............................................................................. 8

Attachment B: System and Facility Location Map ....................................................................................... 9

Attachment C: Inspection and Maintenance Forms ................................................................................... 10

Attachment D: Snow Storage Plan ............................................................................................................ 11


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Project Narrative

1.0 Introduction This Stormwater Management System Operation & Maintenance Plan has been prepared by Howard Stein Hudson (HSH) on behalf of the Town of Southborough (the "Applicant") for the inspection and maintenance of structural Best Management Practices (BMPs) and for measures to prevent pollution associated with the Public Safety Complex in Southborough, MA. The stormwater BMPs include deep sump catch basins, stone check dams, sediment forebay, infiltration basin, water quality units, outlet control structures, rain gardens, water quality swales and grassed swales.

This document has been prepared in accordance with the requirements of the Stormwater Regulations included in the Massachusetts Wetlands Protection Act Regulations (310 CMR 10).

2.0 Purpose This Operation & Maintenance Plan (O&M Plan) is intended to provide a mechanism for the consistent inspection and maintenance of BMPs to be installed on-site. Included in this O&M Plan is a description of each BMP type, the location of individual BMPs, an inspection schedule for each stormwater system and forms to be utilized to document the inspection and maintenance of each BMP. Snow storage areas have been identified and are shown on the plan entitled “Snow Storage Plan”. This O&M Plan is intended for use by the Town of Southborough Department of Public Works (DPW).

The Department of Public Works will be responsible for the operation and maintenance of the stormwater management facilities and associated stormwater management features.

Department of Public Works: 147 Cordaville Road, Southborough, MA 01772 Phone: (508)485-1210 After Hours Phone: Police Dept. (508)485-2147

3.0 Descriptions and Locations of Stormwater BMPs The following post-construction stormwater best management practices (BMPs) have been designed for the Southborough Public Safety Complex to assure its continued performance. A map showing the location of systems and facilities associated with the stormwater management system is provided in Attachment B.


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3.1 DEEP SUMP CATCH BASINS Thirteen (13) deep sump catch basins are designed on-site for the Southborough Public Safety Complex, locations are shown in Attachment B. Deep sump catch basins are designed to act as underground retention systems to remove trash, debris and coarse sediment from stormwater runoff.

3.2 STONE CHECK DAMS Four (4) stone check dams are designed on-site. These structures are designed as a permanent structure to reduce runoff velocities, reduce erosion and gullying in the channel and allow sediments to settle out.

3.3 SEDIMENT FOREBAY One (1) sediment forebay is designed on-site, preceding the infiltration basin. The sediment forebay acts as a pretreatment before stormwater discharges into the infiltration basin and is designed to facilitate the gravity separation of sediments.

3.4 INFILTRATION BASIN One (1) infiltration basin is designed on-site. The basin is located to the South-East of the driveway as shown in Attachment B. The infiltration basin is designed to store water until it exfiltrates through the soil of the basin floor, equipped with a spillway in the case of large storm events.

3.5 WATER QUALITY UNIT One (1) water quality unit is designed on-site. This sub-surface unit is designed to separate sediment and pollutants form the stormwater runoff and prevent further movement through the drainage system.

3.6 OUTLET CONTROL STRUCTURE One (1) outlet control structure is designed on-site. This sub-surface unit is designed to collect stormwater runoff upon reaching the spillway of the infiltration basin and remove trash, debris and coarse sediment.

3.7 RAIN GARDEN One (1) rain garden is designed on site. Rain gardens are designed to treat stormwater before being infiltrated and discharged using soils, plants and microbes. Rain gardens are filled with sandy soil, topped with mulch and dense native vegetation. Stormwater runoff is directed into the cell and percolates through the soil media that acts as a filter.

3.8 WATER QUALITY SWALE One (1) water quality swale is designed on site, located within the driveway media (approximately 195± linear feet). The water quality swale is a vegetated open channel designed to treat the required


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water quality volume, convey runoff from storm events without causing erosion and incorporate special features to enhance stormwater pollutant removal effectiveness.

3.9 GRASSED SWALES Four (4) grassed swales are designed on-site, varying in length and width. Grassed swales are similar to water quality swales, however water quality swales have higher pollutant removal efficiencies than grassed swales.

4.0 Inspection Frequency, Inspection Safety and Maintenance Safety

4.1 INSPECTION FREQUENCY A complete and thorough inspection of the system shall be performed once a month during the first six (6) months and then on a semi-annual basin (spring and fall) using the Inspection and Maintenance Forms provided in Attachment C. A qualified member of the DPW shall complete an Inspection and Maintenance Form for each BMP at each visit. See Section 5 for a description of maintenance procedures.

4.2 INSPECTION SAFETY The inspector performing the inspections of the drainage structures shall have the proper safety equipment (heavy duty gloves, steel-toed boots, hard hat, first aid kits, etc.) and appropriate training before conducting inspections. If the inspection of the drainage structure reveals any safety problems the site activities may need to be modified to reduce or eliminate the safety risk. The inspector shall be aware of the following safety precautions when conducting drainage structure inspections:

Never enter a confined space unless you have proper Occupational Health and Safety Administration (OSHA) training. Do not enter any confined space until the atmosphere has been checked and proper safety equipment is worn or erected.

Avoid entering pipes or conduits without another individual present. If the structural strength of a pipe or conduit is questionable, do not enter the pipe or conduit.

Check the ventilation in the drainage structures before using any ignitable materials. Some drainage structures may be sealed or have poor ventilation, posing a safety risk to the inspector if the vapor comes in contact with an open flame. Also, be sure to allow the drainage structures to vent for a period of time if a peculiar odor is present.



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Check the water depth of the system before taking a step in the water. The water may be deeper than it seems or there may be steep slopes below the water line.

Be aware that nails, broken glass, or other sharp debris may be in the storm water system and can cause injury. Wearing the proper safety clothing will reduce the safety risk associated with these objects.

4.2 MAINTENANCE SAFETY All maintenance work shall be done in compliance with OSHA regulations. Maintenance personal will have the proper safety equipment (heavy duty gloves, steel-toed boots, hard hat, first aid kits, etc.) and training before performing any maintenance on the drainage structures. Maintenance personnel shall be aware of the following safety precautions when performing maintenance on the drainage structures:

Operate equipment safely and in accordance with the manufacturer’s specifications. Equipment operators must remain aware of site personnel at all times to avoid causing injury to others.

Contact Dig Safe System Inc. at 1-888-DIG-SAFE seventy-two (72) hours before excavating a site. Underground utility wires and pipes may be present. Cover or clearly mark excavated areas that cannot be filled in at the end of the day to alert site employees of the potential risk. Also, be aware of overhead electrical wires that could come in contact with maintenance equipment.

Contact Dig Safe System Inc. at 1-888-DIG-SAFE seventy-two (72) hours before excavating a site. Underground utility wires and pipes may be present. Cover or clearly mark excavated areas that cannot be filled in at the end of the day to alert site employees of the potential risk. Also, be aware of overhead electrical wires that could come in contact with maintenance equipment.

Wear gloves if any mechanical parts or structural components are going to be handled. Wearing gloves not only reduces the risk of getting cuts and abrasions, but also reduces the exposure of pollutants to the skin.

5.0 Inspection and Maintenance Procedures The Town of Southborough DPW is responsible for the inspection and maintenance of the stormwater system components. The following list of inspections and maintenance shall be


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performed on the required schedule. All sediment, debris, and hydrocarbons that are removed during the maintenance of the stormwater system components should be properly handled and disposed.

5.1 DEEP SUMP CATCH BASINS a. Inspect quarterly ( January, April, July, October)

b. Clean 2 times per year or when deposits reach ½ the depth of the sump

5.2 STONE CHECK DAMS a. Inspect after every significant rainfall event

b. Repair damage as needed

c. Remove sediment as needed

5.3 SEDIMENT FOREBAY a. Inspect monthly

b. Clean four times per year, removing trash, debris, accumulated organic matter, etc.

5.4 INFILTRATION BASIN a. Inspect twice a year (spring and fall) and when there are discharges through the spillway

b. Clean 2 times per year, removing trash, debris, accumulate organic matter, etc.

c. Mow regularly during growing season

5.5 WATER QUALITY UNIT Follow manufacturer’s recommendations including at minimum:

a. Inspect twice a year (spring and fall), minimum after major storm events

b. Sediment removal is required when the level of sediment has reached 75% of capacity in the isolated sump or when an appreciable level of hydrocarbons and trash has accumulated

c. Remove floatable trash, debris and oil

5.6 OUTLET CONTROL STRUCTURE a. Inspect quarterly ( January, April, July, October)

b. Clean 2 times per year or when deposits reach ½ the depth of the sump


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5.7 RAIN GARDEN a. Inspect and remove trash monthly

b. Clean 2 times per year, removing and replacing dead vegetation, weeds etc.

5.8 WATER QUALITY SWALE a. Inspect every 6 months

b. Remove floatable trash, debris and oil

c. Clean 2 times per year, removing and replacing dead vegetation, weeds etc.

5.9 GRASSED SWALES a. Inspect every 6 months

b. Remove floatable trash, debris and oil

c. Mow regularly during growing season

6.0 Record Keeping An “Inspection and Maintenance Form” shall be filled out each time inspectional or maintenance work is performed. A binder shall be kept by the DPW that contains all of the completed inspection forms and/or photographs and related material. A review of all Operation and Maintenance actions should take place annually to ensure that these Stormwater BMPs are being taken care of in the manner illustrated in this Operation & Maintenance Plan. Additionally, all operation and maintenance records shall be retained for at least five (5) years and be provided to the Planning Board upon request.

7.0 Maintenance Responsibilities and Costs As previously noted, the Town of Southborough DPW will be responsible for compliance with this Operation and Maintenance Plan; and such responsibilities will be recorded in the DPW’s records. The operations and maintenance budget was prepared to provide an approximate annual cost to maintain each proposed BMP in accordance to the MassDEP Stormwater Management Policy in section 5.0. The annual cost to maintain stormwater BMPs on site will be incorporated into the DPW’s annual maintenance budget.


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BMP Type # of BMPs Annual O&M Cost

(per BMP) Total Cost Deep Sump Catch Basin 13 $500 $6,500

Stone Check Dam 4 $100 $400

Sediment Forebay 1 $250 $250

Infiltration Basin 1 $2,500 $2,500

Water Quality Unit 1 $500 $500

Outlet Control Structure 1 $500 $500

Rain Garden 1 $500 $500

Water Quality Swale 1 - -

Grassed Swale 4 - -

Total $11,150

Attachment A: Operation and Maintenance Agreement

Attachment B: System and Facility Location Map

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Attachment C: Inspection and Maintenance Forms

Southborough Public Safety Complex, Southborough, Massachusetts

Prepared by Howard Stein Hudson Page 1 of 1

INSPECTION AND MAINTENANCE FORM STORMWATER BEST MANAGEMENT PRACTICES (BMPs)

Drainage System: Catch Basins Date: Time: Weather/Temp.: Inspector(s): Date of Last Precipitation: Precipitation Amount: Inches Precipitation Type: Location Onsite: Scoring Breakdown: N/A = Not Applicable 1 = Monitor (potential for future problems exist) N/I = Not Investigated 2 = Routine Maintenance Required 0 = Not a problem 3 = Immediate Repair Necessary 1. Stormwater Structures Sediment accumulation >½ sump depth

No Yes 0 1 2 3 Amount: _______ in. **

Evidence of oil/grease accumulation No Yes 0 1 2 3 Other 2. Pipes Broken N/A N/I 0 1 2 3 Clogged N/A N/I 0 1 2 3 Submerged Outlet Pipe N/A N/I 0 1 2 3 Overall Condition Inspector’s Summary: *If sediment depths are greater ½ the depth of sump, sediments should be removed as soon as possible.




Drainage System: Stone Check Dam Date: Time: Weather/Temp.: Inspector(s): Date of Last Precipitation: Precipitation Amount: Inches Precipitation Type: Location Onsite: Scoring Breakdown: N/A = Not Applicable 1 = Monitor (potential for future problems exist) N/I = Not Investigated 2 = Routine Maintenance Required 0 = Not a problem 3 = Immediate Repair Necessary 1. Stormwater Structures Overall Condition N/A N/I 0 1 2 3 Displacement/Erosion N/A N/I 0 1 2 3 Evidence of flow around structure No Yes 0 1 2 3 Sediment accumulation >1” No Yes 0 1 2 3 Amount: _______ in. * Overall Condition Inspector’s Summary:




Drainage System: Sediment Forebay Date: Time: Weather/Temp.: Inspector(s): Date of Last Precipitation: Precipitation Amount: Inches Precipitation Type: Location Onsite: Scoring Breakdown: N/A = Not Applicable 1 = Monitor (potential for future problems exist) N/I = Not Investigated 2 = Routine Maintenance Required 0 = Not a problem 3 = Immediate Repair Necessary 1. Plants Disease/pest problems N/A N/I 0 1 2 3 Weeds N/A N/I 0 1 2 3 Excess growth and/or dead branches N/A N/I 0 1 2 3 2. Grass on Surface Overall Condition N/A N/I 0 1 2 3 Erosion N/A N/I 0 1 2 3 Sediment accumulation >1” No Yes 0 1 2 3 Amount: _______ in. * 3. Riprap Apron Overall Condition N/A N/I 0 1 2 3 Displacement/Erosion N/A N/I 0 1 2 3 Sediment accumulation >1” No Yes 0 1 2 3 Amount: _______ in. * Overall Condition Inspector’s Summary:




Drainage System: Infiltration Basin Date: Time: Weather/Temp.: Inspector(s): Date of Last Precipitation: Precipitation Amount: Inches Precipitation Type: Location Onsite: Scoring Breakdown: N/A = Not Applicable 1 = Monitor (potential for future problems exist) N/I = Not Investigated 2 = Routine Maintenance Required 0 = Not a problem 3 = Immediate Repair Necessary 1. Bioretention Soil Mix Sediment accumulation >1” No Yes 0 1 2 3 Amount: _______ in. * Ponding more than 24 hrs after rain No Yes 0 1 2 3 Amount: _______ in. Soil pH Oil/chemical accumulation in soil bed N/A N/I 0 1 2 3 Other 2. Plants Disease/pest problems N/A N/I 0 1 2 3 Weeds N/A N/I 0 1 2 3 Excess growth and/or dead branches N/A N/I 0 1 2 3 3. Grass on Surface Overall Condition N/A N/I 0 1 2 3 Erosion N/A N/I 0 1 2 3 Sediment accumulation >1” No Yes 0 1 2 3 Amount: _______ in. * 3. Pretreatment Devices Overall Condition N/A N/I 0 1 2 3 Erosion N/A N/I 0 1 2 3 Sediment accumulation >1” No Yes 0 1 2 3 Amount: _______ in. * Overall Condition Inspector’s Summary:




Drainage System: Water Quality Unit Date: Time: Weather/Temp.: Inspector(s): Date of Last Precipitation: Precipitation Amount: Inches Precipitation Type: Location Onsite: Scoring Breakdown: N/A = Not Applicable 1 = Monitor (potential for future problems exist) N/I = Not Investigated 2 = Routine Maintenance Required 0 = Not a problem 3 = Immediate Repair Necessary 1. Stormwater Structures Sediment accumulation >75% capacity of isolated sump

No Yes 0 1 2 3 Amount: _______ in. **

Evidence of oil/grease accumulation No Yes 0 1 2 3 Other 2. Pipes Broken N/A N/I 0 1 2 3 Clogged N/A N/I 0 1 2 3 Submerged Outlet Pipe N/A N/I 0 1 2 3 Overall Condition Inspector’s Summary: *See manufacturer’s operation and maintenance manual for additional details.




Drainage System: Outlet Control Structure Date: Time: Weather/Temp.: Inspector(s): Date of Last Precipitation: Precipitation Amount: Inches Precipitation Type: Location Onsite: ` Scoring Breakdown: N/A = Not Applicable 1 = Monitor (potential for future problems exist) N/I = Not Investigated 2 = Routine Maintenance Required 0 = Not a problem 3 = Immediate Repair Necessary 1. Stormwater Structures Sediment accumulation >½ sump depth

No Yes 0 1 2 3 Amount: _______ in. **

Evidence of oil/grease accumulation No Yes 0 1 2 3 Other 2. Pipes Broken N/A N/I 0 1 2 3 Clogged N/A N/I 0 1 2 3 Submerged Outlet Pipe N/A N/I 0 1 2 3 Overall Condition Inspector’s Summary: *If sediment depths are greater ½ the depth of sump, sediments should be removed as soon as possible.




Drainage System: Rain Garden Date: Time: Weather/Temp.: Inspector(s): Date of Last Precipitation: Precipitation Amount: Inches Precipitation Type: Location On-Site: Scoring Breakdown: N/A = Not Applicable 1 = Monitor (potential for future problems exist) N/I = Not Investigated 2 = Routine Maintenance Required 0 = Not a problem 3 = Immediate Repair Necessary 1. Bioretention Soil Mix Sediment accumulation >1” No Yes 0 1 2 3 Amount: _______ in. * Ponding more than 24 hrs after rain No Yes 0 1 2 3 Amount: _______ in. Soil pH Oil/chemical accumulation in soil bed N/A N/I 0 1 2 3 Other 2. Plants Disease/pest problems N/A N/I 0 1 2 3 Weeds N/A N/I 0 1 2 3 Excess growth and/or dead branches N/A N/I 0 1 2 3 3. Mulch/Grass** on Surface Overall Condition N/A N/I 0 1 2 3 Displacement/Erosion N/A N/I 0 1 2 3 Sediment accumulation >1” No Yes 0 1 2 3 Amount: _______ in. * 4. Underdrain (if applicable***) Broken N/A N/I 0 1 2 3 Clogged N/A N/I 0 1 2 3 5. Outlet Broken N/A N/I 0 1 2 3 Clogged N/A N/I 0 1 2 3 Submerged Outlet Pipe N/A N/I 0 1 2 3 Overall Condition Inspector’s Summary: *If sediment depths are greater than one inch, sediments should be removed as soon as possible.




Drainage System: Water Quality Swale Date: Time: Weather/Temp.: Inspector(s): Date of Last Precipitation: Precipitation Amount: Inches Precipitation Type: Location Onsite: Scoring Breakdown: N/A = Not Applicable 1 = Monitor (potential for future problems exist) N/I = Not Investigated 2 = Routine Maintenance Required 0 = Not a problem 3 = Immediate Repair Necessary 1. Bioretention Soil Mix Sediment accumulation >1” No Yes 0 1 2 3 Amount: _______ in. * Ponding more than 24 hrs after rain No Yes 0 1 2 3 Amount: _______ in. Soil pH Oil/chemical accumulation in soil bed N/A N/I 0 1 2 3 Other 2. Plants Disease/pest problems N/A N/I 0 1 2 3 Weeds N/A N/I 0 1 2 3 Excess growth and/or dead branches N/A N/I 0 1 2 3 3. Grass on Surface Overall Condition N/A N/I 0 1 2 3 Erosion N/A N/I 0 1 2 3 Sediment accumulation >1” No Yes 0 1 2 3 Amount: _______ in. * Overall Condition Inspector’s Summary: *If sediment depths are greater than one inch, sediments should be removed as soon as possible.




Drainage System: Grassed Swale Date: Time: Weather/Temp.: Inspector(s): Date of Last Precipitation: Precipitation Amount: Inches Precipitation Type: Location Onsite: Scoring Breakdown: N/A = Not Applicable 1 = Monitor (potential for future problems exist) N/I = Not Investigated 2 = Routine Maintenance Required 0 = Not a problem 3 = Immediate Repair Necessary 1. Bioretention Soil Mix Sediment accumulation >1” No Yes 0 1 2 3 Amount: _______ in. * Ponding more than 24 hrs after rain No Yes 0 1 2 3 Amount: _______ in. Soil pH Oil/chemical accumulation in soil bed N/A N/I 0 1 2 3 Other 2. Plants Disease/pest problems N/A N/I 0 1 2 3 Weeds N/A N/I 0 1 2 3 Excess growth and/or dead branches N/A N/I 0 1 2 3 3. Grass on Surface Overall Condition N/A N/I 0 1 2 3 Erosion N/A N/I 0 1 2 3 Sediment accumulation >1” No Yes 0 1 2 3 Amount: _______ in. * Overall Condition Inspector’s Summary: *If sediment depths are greater than one inch, sediments should be removed as soon as possible.

Attachment D: Snow Storage Plan

Approximate Scale: 1" = 100'-0"Date: 12-01-2017

NOTICE OF INTENT

Southborough Public Safety Complex

December 1, 2017

Figure 1. SNOW STORAGE PLAN

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