Attachment 12 - HAFB Stormwater IDDE Plan.pdf

Appendix F IDDE Program

APPENDIX F

ILLICIT DISCHARGE DETECTION ELIMINATION

PROGRAM

HANSCOM AIR FORCE BASE

Contract No. GS-10F-0103N

Prepared for:

Hanscom Air Force Base 66 ABG/CEIE, Middlesex

County, Massachusetts

Prepared by:

BB&E, Inc.

July 2019

Illicit Discharge Deterction and Elimination Program i Hanscom Air Force Base July 2019 Massachusetts

Table of Contents 1 Introduction

1.1 MS4 Program

1.2 Illicit Discharges

1.3 Allowable Non-Stormwater Discharges

1.4 Receiving Waters and Impairments

1.5 IDDE Program and Goals, Framework, and Timeline

2 Authority and Statement of IDDE Responsibility

2.1 Legal Authority

2.2 Statement of Responsibilities

3 Stormwater System Mapping

3.1 Phase I Mapping

3.2 Phase II Mapping

3.3 Additional Recommended Mapping Elements

4 Sanitary Sewer Overflows

5 Assessment and Priority Ranking of Outfalls

5.1 Outfall Catchment Delineations

5.2 Outfall and Interconnection Inventory and Initial Ranking

6 Dry Weather Outfall Screening and Sampling

6.1 Weather Conditions

6.2 Performing Dry Weather Screening

6.3 Interpreting Outfall Sampling Results

6.4 Follow-up Ranking of Outfalls and Interconnections

7 Catchment Investigations

7.1 System Vulnerability Factors

7.2 Dry Weather Manhole Inspections

7.3 Wet Weather Outfall Sampling

7.4 Source Isolation and Confirmation

7.4.1 Sandbagging

7.4.2 Smoke Testing

7.4.3 Dye Testing

7.4.4 CCTV/Video Inspection

7.4.5 Optical Brightener Monitoring

7.4.6 IDDE Canines

7.5 Illicit Discharge Removal

7.5.1 Confirmatory Outfall Screening

7.6 Ongoing Screening

8 Training

9 Progress Reporting

References

Illicit Discharge Deterction and Elimination Program ii

FIGURES

Figure 1-1. IDDE Investigation Procedure Framework

TABLES

Table 1-1. Impaired Waters Bedford, Massachusetts Table 1-2. IDDE Program Implementation Timeline Table 4-1. SSO Inventory Table 5-1. Outfall Inventory and Priority Ranking Matrix Table 6-1. Benchmark Field Measurements for Select Parameters Table 7-1. Outfall Catchment System Vulnerability Factor Inventory

ATTACHMENTS

Attachment A Legal Authority Attachment B Storm System Mapping and Catchment Delineation Attachment C Stormwater Sampling Procedures and Field Forms Attachment D IDDE Employee Training Record Attachment E Field Standard Operating Procedures

Illicit Discharge Deterction and Elimination Program iii

ABBREVIATIONS AND ACRONYMS

°C Degrees Centigrade AFB Air Force Base AFCEC Air Force Civil Engineer Center BB&E BB&E, Inc BOH Board of Health BMP Best Management Practice CCTV Closed-circuit television CFR Code of Federal Regulations CFU Colony-forming unit CMRSWC Central Massachusetts Regional Stormwater Coalition CFR Code of Federal Regulations IDDE Illicit Discharge Detection and Elimination LOS level of service MA Massachusetts Mass DEP Massachusetts Department of Environmental Protection mg/l milligrams per liter MPN Most Probable Number MS4 Municipal Separate Storm Sewer System msl mean sea level NA not applicable NPDES National Pollution Discharge Elimination System O&M operations and maintenance SM Standard Methods SOP Standard Operating Procedure SSO Sanitary Sewer Overflow SVF System Vulnerability Factor SWMP Stormwater Management Plan TMDL total maximum daily load µs/cm Microsiemens per centimeter U.S. United States USEPA United States Environmental Protection Agency

Illicit Discharge Deterction and Elimination Program 1

1 Introduction The Air Force Civil Engineer Center (AFCEC) has contracted BB&E, Inc. (BB&E) to provide a Stormwater Management Plan (SWMP) update for Hanscom Air Force Base (AFB), under Contract Number GS-10F-0103N. This Illicit Discharge Detection and Elimination (IDDE) Program was developed as an appendix to the SWMP, to meet the Minimum Control Measures outlined in the General Permit for Stormwater Discharges from Small Municipal Separate Storm Sewer Systems in Massachusetts (2016 MA MS4 General Permit). This IDDE program is based on the template provided by the Illicit Discharge Detection and Elimination (IDDE) Plan (Fuss & O’Neill, 2016), developed by Central Massachusetts Regional Stormwater Coalition (CMRSWC) and Fuss & O’Neill. The Draft Hanscom IDDE Program was initially developed in 2017 by Cape Environmental Management Inc.

1.1 MS4 Program

This IDDE Program has been developed by BB&E on behalf of Hanscom Air Force Base to address the requirements of the United States Environmental Protection Agency’s (USEPA’s) 2016 National Pollutant Discharge Elimination System (NPDES) General Permit for Stormwater Discharges from Small Municipal Separate Storm Sewer Systems (MS4) in Massachusetts, hereafter referred to as the “2016 Massachusetts MS4 Permit” or “MS4 Permit”.

The 2016 Massachusetts MS4 Permit requires that each permittee implement an IDDE Program to systematically find and eliminate sources of non-stormwater discharges to its municipal separate storm sewer system and implement procedures to prevent such discharges. The IDDE Program must also be recorded in a written (hardcopy or electronic) document. This IDDE Program has been prepared to address this requirement.

1.2 Illicit Discharges

An “illicit discharge” is any discharge to a drainage system that is not composed entirely of stormwater, with the exception of discharges pursuant to a NPDES permit (other than the NPDES permit for discharges from the MS4) and discharges resulting from fire-fighting activities.

Illicit discharges may take a variety of forms. Illicit discharges may enter the drainage system through direct or indirect connections. Direct connections may be relatively obvious, such as cross-connections of sewer services to the storm drain system. Indirect illicit discharges may be more difficult to detect or address, such as failing septic systems that discharge untreated sewage to a ditch within the MS4, or a sump pump that discharges contaminated water on an intermittent basis.

Some illicit discharges result from illegal activity , such as dumping used oil (or other pollutant) into catch basins, a resident or contractor illegally tapping a new sewer lateral into a storm drainpipe to avoid the costs of a sewer connection fee and service, and illegal dumping of yard wastes into surface waters. Some illicit discharges are related to the unsuitability of original infrastructure to the modern regulatory environment. Examples of illicit discharges in this category include connected floor drains in old buildings, as well as sanitary sewer overflows that enter the

Illicit Discharge Deterction and Elimination Program 2 drainage system. Sump pumps legally connected to the storm drain system may be used inappropriately, such as for the disposal of floor wash water or old household products, in many cases due to a lack of understanding on the part of the homeowner.

Elimination of some discharges may require substantial costs and efforts, such as funding and designing a project to reconnect sanitary sewer laterals. Others, such as improving self- policing of dog waste management, can be accomplished by outreach in conjunction with the minimal additional cost of dog waste bins and the municipal commitment to disposal of collected materials on a regular basis.

Regardless of the intention, when not addressed, illicit discharges can contribute high levels of pollutants, such as heavy metals, toxics, oil, grease, solvents, nutrients, and pathogens to surface waters.

1.3 Allowable Non-Stormwater Discharges

The following categories of non-stormwater discharges are allowed under the MS4 Permit unless the permittee, USEPA or Massachusetts Department of Environmental Protection (MassDEP) identifies any category or individual discharge of non-stormwater discharge as a significant contributor of pollutants to the MS4.

• Water line flushing

• Landscape irrigation

• Diverted stream flows

• Rising ground water

• Uncontaminated ground water infiltration (as defined at 40 CFR 35.2005(20))

• Uncontaminated pumped groundwater

• Discharge from potable water sources

• Foundation drains

• Air conditioning condensation

• Irrigation water, springs

• Water from crawl space pumps

• Footing drains

• Lawn watering

• Individual resident car washing

• De-chlorinated swimming pool discharges

• Street wash waters

If these discharges are identified as significant contributors to the MS4, they must be considered an “illicit discharge” and addressed in the IDDE Plan (i.e., control these sources so they are no longer significant contributors of pollutants, and/or eliminate them entirely).

1.4 Receiving Waters and Impairments

Table 1-1 lists the “impaired waters” within the boundaries of Hanscom AFB’s regulated area based on the Proposed 2016 Massachusetts Integrated List of Waters produced by MassDEP

Illicit Discharge Deterction and Elimination Program 3 every two years. Impaired waters are water bodies that do not meet water quality standards for one or more designated use(s) such as recreation or aquatic habitat.

Table 1-1. Impaired Waters Bedford, Massachusetts

Water Body Name

Segment ID

Category

Impairment(s) Associated

Approved TMDL

Shawsheen River MA83-08 5 Escherichia coli 2587

Fecal Coliform 2587

Oxygen, Dissolved

Physical substrate habitat alterations

Category 5 Waters – impaired water bodies that require a TMDL.

“Approved TMDLs” are those that have been approved by EPA as of the date of issuance of the 2016 MS4 Permit.

The TMDL for Bacteria in the Shawsheen River Basin lists control measures for the TMDL as watershed management, stormwater management, illicit discharge detection and elimination, combined and sanitary sewer overflow abatement, and septic system maintenance. Illicit sewer connections and sanitary sewer overflow have zero waste load allocations and load allocations.

Illicit sewer connections and sewer line breaks were determined to be the source components of greatest significance during dry weather, low flow conditions. Reductions from sewer breaks and illicit sewer connections are required to achieve compliance with the water quality standards during dry weather. The TMDL indicates a broken sewage main was discovered at Hanscom AFB and was fixed in 1997. Three additional sewer line breaks occurred outside the Hanscom AFB boundary along Hartwell Ave. in 2014, 2017 and 2018. These incidences are recorded in Table 4-1. Further examination of the sewer lines should be conducted to identify any additional leaks or breaks.

The TMDL recommends communities implement illegal connection identification and removal program.

1.5 IDDE Program and Goals, Framework, and Timeline

The goals of the IDDE program are to find and eliminate illicit discharges to municipal separate storm sewer system and to prevent illicit discharges from happening in the future.

The program consists of the following major components as outlined in the MS4 Permit:

• Legal authority and regulatory mechanism to prohibit illicit discharges and enforce this prohibition

• Storm system mapping

• Inventory and ranking of outfalls

Illicit Discharge Deterction and Elimination Program 4

• Dry weather outfall screening

• Catchment investigations

• Identification/confirmation of illicit sources

• Illicit discharge removal

• Follow-up screening

• Employee training.

The IDDE investigation procedure framework is shown in Figure 1-1. The required timeline for implementing the IDDE program is shown in Table 1-2.

Figure 1-1. IDDE Investigation Procedure Framework

Illicit Discharge Deterction and Elimination Program 5

Table 1-2. IDDE Program Implementation Timeline

IDDE Program Requirement

Completion Date from Effective Date of Permit

1 Year 1.5 Years 2 Years 3 Years 7 Years 10 Years Written IDDE Program Plan X SSO Inventory X Written Catchment Investigation Procedure

X

Phase I Mapping X Phase II Mapping X IDDE Regulatory Mechanism or By-law (if not already in place)

Dry Weather Outfall Screening X Follow-up Ranking of Outfalls and Interconnections

Catchment Investigations – Problem Outfalls

Catchment Investigations – all Problem, High and Low Priority Outfalls

Illicit Discharge Deterction and Elimination Program 6

2 Authority and Statement of IDDE Responsibility

2.1 Legal Authority

Hanscom AFB, which is owned and operated by the United States (Federal Facility), qualifies as a Non-Traditional MS4. Therefore, Hanscom AFB has adopted a Stormwater Illicit Discharge Prohibition Policy Statement (Attachment A) to provide adequate legal authority to:

• Prohibit illicit discharges

• Investigate suspected illicit discharges

• Eliminate illicit discharges, including discharges from properties not owned by or controlled by the MS4 that discharge into the MS4 system

• Implement appropriate enforcement procedures and actions.

2.2 Statement of Responsibilities

The Hanscom AFB Stormwater Coordinator is responsible for implementing the IDDE program provisions. The Hanscom AFB Civil Engineering or Department of Public Works may provide support if needed.

Illicit Discharge Deterction and Elimination Program 7

Massachusetts

3 Stormwater System Mapping Hanscom AFB maintains a current stormwater system map in GIS format. The stormwater system map is intended to facilitate the identification of key infrastructure, factors influencing proper system operation, and the potential for illicit discharges.

The 2016 MS4 Permit requires the storm system map be updated in two phases as outlined below.

Hanscom AFB has completed all applicable Phase I mapping requirement and will update the stormwater system map pursuant to Phase II requirements by July 1, 2028. Hanscom AFB will report on the progress towards completion of the storm system map in each annual report.

Updates to the stormwater mapping will be included in Attachment B.

3.1 Phase I Mapping

Phase I mapping requirements are identified on the stormwater system map in Attachment B and include the following information as applicable:

• Outfalls and receiving waters (previously required by the MS4-2003 permit)

• Open channel conveyances (swales, ditches, etc.)

• Interconnections with other MS4s and other storm sewer systems

• Municipally owned stormwater treatment structures

• Water bodies identified by name and indication of all use impairments as identified on the most recent EPA approved Massachusetts Integrated List of Waters report

• Initial catchment delineations. Topographic contours and drainage system information may be used to produce initial catchment delineations.

3.2 Phase II Mapping

Phase II mapping must be completed within 10 years of the effective date of the permit (July 1, 2028) and include the following information as applicable:

• Outfall spatial location (latitude and longitude with a minimum accuracy of +/-30 feet)

• Pipes

• Manholes

• Catch basins

• Refined catchment delineations. Catchment delineations must be updated to reflect information collected during catchment investigations.

• Municipal Sanitary Sewer system (if available)

• Municipal combined sewer system (if applicable).

Hanscom AFB will update its stormwater mapping by July 1, 2028 to include the remaining Phase II information.

Illicit Discharge Deterction and Elimination Program 8

3.3 Additional Recommended Mapping Elements

The 2016 MS4 Permit recommends but does not require the addition of the following elements to the storm system mapping. Hanscom AFB will evaluate including these recommended elements:

• Storm sewer material, size (pipe diameter), age

• Sanitary sewer system material, size (pipe diameter), age

• Privately owned stormwater treatment structures

• Where a municipal sanitary sewer system exists, properties known or suspected to be served by a septic system, especially in high density urban areas

• Area where the permittee’s MS4 has received or could receive flow from septic system discharges

• Seasonal high-water table elevations impacting sanitary alignments

• Topography

• Orthophotography

• Alignments, dates and representation of work completed of past illicit discharge investigations

• Locations of suspected confirmed and corrected illicit discharges with dates and flow estimates.

Illicit Discharge Deterction and Elimination Program 9

4 Sanitary Sewer Overflows The 2016 MS4 Permit requires municipalities to prohibit illicit discharges, including sanitary sewer overflows (SSOs), to the separate storm sewer system. SSOs are discharges of untreated sanitary wastewater from a municipal sanitary sewer that can contaminate surface waters, cause serious water quality problems and property damage, and threaten public health. SSOs can be caused by blockages, line breaks, sewer defects that allow stormwater and groundwater to overload the system, power failures, improper sewer design, and vandalism.

Hanscom AFB has completed an inventory of SSOs that have discharged to the MS4 within the five years prior to the effective date of the 2016 MS4 Permit, based on review of available documentation pertaining to SSOs (Table 4-1). The inventory includes all SSOs that occurred in the past five years during wet or dry weather resulting from inadequate conveyance capacities or where interconnectivity of the storm and sanitary sewer infrastructure allows for transfer of flow between systems.

Upon detection of an SSO, Hanscom AFB will eliminate it as expeditiously as possible and take interim measures to minimize the discharge of pollutants to and from its MS4 until the SSO is eliminated. Upon becoming aware of an SSO to the MS4, Hanscom AFB will provide oral notice to EPA within 24 hours and written notice to EPA and MassDEP within five days of becoming aware of the SSO occurrence.

The inventory in Table 4-1 will be updated by Hanscom AFB when new SSOs are detected.

The SSO inventory will be included in the annual report, including the status of mitigation and corrective measures to address each identified SSO.

Illicit Discharge Deterction and Elimination Program 10

Table 4-1. SSO Inventory Hanscom AFB, Massachusetts

Revision Date: July 2019

SSO Location1 Discharge

Statement2

Date3 Time Start3

Time End3

Estimated Volume4

Description5 Mitigation

Completed6

Mitigation Planned7

Along Hartwell Ave, near Wood St.

Entered wetlands feeding Kiln Brook

9/23/2014 9/23/2014

8:15 AM

9/23/20148

11:45 AM

37,000 gal Broken Force Main

Broken line repaired, discussion with regulators and community advised no further disinfection actions in the wetlands to avoid greater damage.

Initiating request to higher HQ for resources to conduct assessment of line to determine condition and potential need for additional repairs or replacement to prevent future leaks.

Along Hartwell Ave, near 110 Hartwell Ave.

Entered storm drain and wetlands feeding Kiln Brook

2/16/2017 2/16/2017

2:30 PM

2/16/2017

6:05 PM

8,200 gal Broken Force Main.

Discovered to be a 2” hole in pipe

Broken line repaired, discussion with regulators and community advised no further disinfection actions in the wetlands to avoid greater damage.

N/A

Along Hartwell Ave, near 110 Hartwell Ave.

Entered wetlands feeding Kiln Brook

12/4/2017 12/4/2017

11:50 AM

12/6/2017

6:00 PM

25,500 gal Broken Force Main

Broken line repaired, discussion with regulators and community advised no further disinfection actions in the wetlands to avoid greater damage.

As a result of numerous incidents of sewer force main breaks along Hartwell Avenue, Hanscom AFB recently received funding for and awarded a construction project for replacement of portions of this line.

Construction is anticipated to start in mid-June 2018.

Illicit Discharge Deterction and Elimination Program 11

Along Hartwell Ave, near 110 Hartwell Ave.

Entered wetlands feeding Kiln Brook

4/30/2018 4/30/2018

12:00 PM

4/30/2018

4:30 PM

35,000 gal Broken Force Main

Broken line repaired, discussion with regulators and community advised no further disinfection actions in the wetlands to avoid greater damage.

Force main replacement project initiated in June 2018 and completed Aug 28, 2018.

No further action planned

1 Location (approximate street crossing/address and receiving water, if any) 2 A clear statement of whether the discharge entered a surface water directly or entered the MS4 3 Date(s) and time(s) of each known SSO occurrence (i.e., beginning and end of any known discharge) 4 Estimated volume(s) of the occurrence 5 Description of the occurrence indicating known or suspected cause(s) 6 Mitigation and corrective measures completed with dates implemented 7 Mitigation and corrective measures planned with implementation schedules

Illicit Discharge Deterction and Elimination Program 12

5 Assessment and Priority Ranking of Outfalls The 2016 MS4 Permit requires an assessment and priority ranking of outfalls in terms of their potential to have illicit discharges and SSOs and the related public health significance. The ranking helps determine the priority order for performing IDDE investigations and meeting permit milestones.

5.1 Outfall Catchment Delineations

A catchment is the area that drains to an individual outfall or interconnection. The catchments for each of the MS4 outfalls will be delineated to define contributing areas for investigation of potential sources of illicit discharges. Catchments are typically delineated based on topographic contours and mapped drainage infrastructure, where available.

As described in Section 3, initial catchment delineations were completed as part of the Phase I mapping. However, the catchments were not delineated based on each individual outfall due to large number of outfalls and small catchments within Hanscom AFB. The Shawsheen River runs through the center of Hanscom AFB. Therefore, over 25 individual outfalls drain into an approximately one-mile section of the Shawsheen River. Many of these outfalls drain only parking lots or roof runoff. Additionally, many of the stormwater drainage systems are interconnected with multiple outfall locations. Delineating each of these catchments was deemed to be impractical in an area as small as Hanscom AFB. Instead catchment delineations were based on topography and stormwater drainage grouping. Each catchment basin has 2 to 12 outfalls. It is assumed that each catchment basin is small enough to trace illicit discharges and will be effective in remaining in compliance with the goals of the MS4 permit. Each outfall and its corresponding catchment basin are identified in Table 5-1.

A refined catchment delineation will be completed as part of the Phase II mapping to reflect information collected during catchment investigations

5.2 Outfall and Interconnection Inventory and Initial Ranking Hanscom AFB has completed an initial outfall and interconnection inventory and priority ranking to assess illicit discharge potential based on existing information. An updated inventory and ranking will be provided in each annual report. The inventory will be updated annually to include data collected in connection with dry weather screening and other relevant inspections.

The ranking will be continuously updated as dry weather screening information becomes available but shall be completed within three years of effective permit date (July 1, 2021).

The majority of the stormwater drainage network on Hanscom AFB outfalls to the Shawsheen River. Approximately, 0.5 miles of the Shawsheen River is culverted through the center of Hanscom AFB and contains many stormwater drainage discharge points. It is not possible to screen or sample all of these outfalls at the point where they exit into the culverted stream.

Therefore, the nearest manhole upstream in the stormwater drainage network will be selected as a sample point. These outfalls and the upstream manhole sampling points are labeled with both an Outfall ID and Manhole No. in Table 5-1. Some small stormwater drainage systems, which

Illicit Discharge Deterction and Elimination Program 13 drain parking lots, roofs, and green spaces close to the culverted stream, do not have a manhole access point anywhere in the system. These portions of the stormwater drainage system are excluded from the IDDE plan due to low likelihood of illicit discharge and impracticality of collecting a dry weather screening sample.

The outfall and interconnection inventory identifies each outfall and interconnection discharging from the MS4 and records its location on the Stormwater System Map located in Attachment B. The condition of each outfall and screening results will be documented on inspections forms and filed in Attachment C, as well as submitted in each annual report.

Outfalls and interconnections are classified into one of the following categories:

1. Problem Outfalls: Outfalls/interconnections with known or suspected contributions of illicit discharges based on existing information shall be designated as Problem Outfalls. This shall include any outfalls/interconnections where previous screening indicates likely sewer input. Likely sewer input indicators are any of the following:

• Olfactory or visual evidence of sewage,

• Ammonia ≥ 0.5 mg/L, surfactants ≥ 0.25 mg/L, and bacteria levels greater than the water quality criteria applicable to the receiving water, or

• Ammonia ≥ 0.5 mg/L, surfactants ≥ 0.25 mg/L, and detectable levels of chlorine.

Dry weather screening and sampling, as described in Section 6 of this IDDE Plan and Part 2.3.4.7.b of the MS4 Permit, is not required for Problem Outfalls.

2. High Priority Outfalls: Outfalls/interconnections that have not been classified as Problem Outfalls and that are:

• Discharging to an area of concern to public health due to proximity of public beaches, recreational areas, drinking water supplies or shellfish beds

• Determined by the permittee as high priority based on the characteristics listed below or other available information.

3. Low Priority Outfalls: Outfalls/interconnections determined by the permittee as low priority based on the characteristics listed below or other available information.

4. Excluded outfalls: Outfalls/interconnections with no potential for illicit discharges may be excluded from the IDDE program. This category is limited to roadway drainage in undeveloped areas with no dwellings and no sanitary sewers; drainage for athletic fields, parks or undeveloped green space and associated parking without services; cross-country drainage alignments (that neither cross nor are in proximity to sanitary sewer alignments) through undeveloped land.

Outfalls will be ranked into the above priority categories (except for excluded outfalls, which may be excluded from the IDDE program) based on the following characteristics of the defined initial catchment areas, where information is available. Additional relevant characteristics, including location-specific characteristics, may be considered but must be documented in this IDDE Plan. The following characteristics may be deleted where data is not available or that do not apply.

• Previous screening results – previous screening/sampling results indicate likely sewer

Illicit Discharge Deterction and Elimination Program 14 input (see criteria above for Problem Outfalls).

• Past discharge complaints and reports.

• Poor receiving water quality – the following guidelines are recommended to identify waters as having a high illicit discharge potential:

o Exceeding water quality standards for bacteria o Ammonia levels above 0.5 mg/l o Surfactants levels greater than or equal to 0.25 mg/l

Density of generating sites – Generating sites are those places, including institutional, municipal, commercial, or industrial sites, with a potential to generate pollutants that could contribute to illicit discharges. Examples of these sites include, but are not limited to, car dealers; car washes; gas stations; garden centers; and industrial manufacturing areas.

• Age of development and infrastructure – Industrial areas greater than 40 years old and areas where the sanitary sewer system is more than 40 years old will probably have a high illicit discharge potential. Developments 20 years or younger will probably have a low illicit discharge potential.

• Sewer conversion – Contributing catchment areas that were once serviced by septic systems, but have been converted to sewer connections may have a high illicit discharge potential.

• Historic combined sewer systems – Contributing areas that were once serviced by a combined sewer system, but have been separated may have a high illicit discharge potential.

• Surrounding density of aging septic systems – Septic systems thirty years or older in residential land use areas are prone to have failures and may have a high illicit discharge potential.

• Culverted streams – Any river or stream that is culverted for distances greater than a simple roadway crossing may have a high illicit discharge potential.

• Water quality limited waterbodies that receive a discharge from the MS4 or waters with approved TMDLs applicable to the permittee, where illicit discharges have the potential to contain the pollutant identified as the cause of the water quality impairment.

Table 5-1 provides an outfall inventory and priority ranking matrix.

Illicit Discharge Deterction and Elimination Program 15

Table 5-1. Outfall Inventory and Priority Ranking Matrix

Revision Date: July 2019

Outfall ID

Receiving Water

Previous

Screening Results Indicate Likely Sewer Input? 1

Discharging to Area of Concern to Public Health? 2

Frequency of

Past Discharge Complaints

Receiving

Water Quality 3

Density of Generating

Sites 4

Age/ Type of

Development/ Infrastructure 5

Historic Combined Sewers or Septic? 6

Aging Septic?7

Culverted Streams?8

Sub- Watershed

Basin

Additional Characteristics

Score

Priority Ranking9

Information Source

Outfall inspections and sample results

GIS Maps

Base Staff

Impaired Waters

List

Land Use/GIS Maps, Aerial Photography

Land Use Information, Visual Observation

Base Staff, Land Use, GIS and Storm

System Maps

Other

Scoring Criteria

Yes = 3 (Problem Outfall)

No = 0

Yes = 3

Frequent = 3 Occasional = 2

None = 0

Poor = 3 Fair = 2

Good = 0

High = 3 Medium = 2

Low = 1

High = 3 Medium = 2

Low = 1

TBD

OF 1 Shawsheen River NA 0 0 2 1 3 0 3 0 6 Drains Outdoor storage area in CEU 9 Low

OF 2 Shawsheen River NA 3 0 2 2 3 0 3 0 6 Drains CEU roads and parking, chemical storage in area 13

High

OF 3 Shawsheen River NA 0 0 2 2 3 0 3 0 6 Drains CEU roads and parking, chemical storage in area 10

Low

OF 4 Shawsheen River NA 0 0 2 1 1 0 3 0 6 Drains one CEU parking lot 7 Low OF 5 Shawsheen River NA 0 0 2 1 2 0 3 0 6 Drains CEU roads 8 Low OF 6 – MH192A Shawsheen River NA 0 0 2 3 3 0 3 0 1A Drains commissary, parking lots, fire station, Aero Club, automotive hobby shop, and waste treatment building. 11

High

OF 6 – MH84 Shawsheen River NA 0 0 2 2 2 0 3 0 1A Drains commissary, parking lots, research buildings.

9 Low

OF 7 Shawsheen River Culvert NA 0 0 2 2 1 0 3 0 2A_1 Drains large roadway area, research buildings, and security buildings

8 Low

OF 8 Shawsheen River Culvert NA 0 0 2 2 2 0 3 0 2A_1 Drains large portion of roads, parking lots, and research buildings. 9

Low

OF 9 – M501,

502, 607

Shawsheen River Culvert NA 0 0 2 3 3 0 3 0 2A_2 Drains portion of vehicle maintenance shop, officers’ quarters, and Eng. Storage 11

High

OF 10 – M34 Shawsheen River Culvert NA 0 0 2 1 1 0 3 0 2A_1 Drains roadways and storage building 7 Low OF 11 – M290 Shawsheen River Culvert NA 0 0 2 1 1 0 3 0 2A_1 Drains parking lots and gym buildings

7 Low

OF 12 Shawsheen River Culvert NA 0 2 2 1 0 3 3 2A_2 Drains wetland, roads, storage, 11 High OF 13 – M506 Shawsheen River Culvert NA 0 0 2 1 1 0 3 0 2A_1 Drains roads and gym building 7 Low OF 14 – M308 Shawsheen River Culvert NA 0 0 2 1 1 0 3 0 2A_1 Drains roadway and recreation building 7 Low OF 15 – M438 Shawsheen River Culvert NA 0 0 2 3 2 0 3 3 2A_3 Drains wetland, roadways, swimming

13 High

OF 16 Shawsheen River NA 3 0 2 2 2 0 3 0 2A_3 Drains roadways and research/admin

12 High OF 17 Shawsheen River NA 3 0 2 1 1 0 3 0 2A_1 Drains small park and road 10 Low OF 18 Shawsheen River NA 3 0 2 1 1 0 3 0 2A_3 Drains small parking lot 10 Low OF 19 Shawsheen River NA 2A_1 Drains only parks Excluded OF 20 Shawsheen River NA 3 0 1 1 2 0 3 0 2A_1 Drains multiple roads and office buildings 10 Low OF 21 Shawsheen River NA 3 0 2 1 1 0 3 0 2A_1 Drains roadways 10 Low

Illicit Discharge Deterction and Elimination Program 16

Receiving Water

Previous

Screening Results Indicate Likely Sewer Input? 1

Discharging to Area of Concern to Public Health? 2

Frequency of

Past Discharge Complaints

Quality 3

Density of Generating

Sites 4

Age/ Type of

Development/ Infrastructure 5

Historic Combined Sewers or Septic? 6

Aging Septic?7

Culverted Streams?8

Sub- Watershed

Basin

Additional Characteristics

Score

Priority Ranking9

Information Source

Outfall inspections and sample results

Impaired Waters

List

Land Use/GIS Maps, Aerial Photography

Land Use Information, Visual Observation

Base Staff, Land Use, GIS and Storm

System Maps

Other

Scoring Criteria

Yes = 3 (Problem Outfall)

Frequent = 3 Occasional = 2

None = 0

Poor = 3 Fair = 2

Good = 0

High = 3 Medium = 2

Low = 1

High = 3 Medium = 2

Low = 1

TBD

OF 22 Shawsheen River NA 3 0 2 2 2 0 3 0 2A_1 Drains Med Clinic 12 High OF 23 Shawsheen River NA 3 0 2 2 1 0 3 3 2A_1 Drains Med Clinic, Temp School and wetland 14 High

OF 24 Shawsheen River NA 3 0 2 1 1 0 3 0 2A_4 Drains new middle school 10 Low OF 25 Shawsheen River NA 3 0 2 1 1 0 3 0 2A_4 Drains new middle school 10 Low OF 26 Shawsheen River NA 3 0 2 1 1 0 3 0 2A_5 Drains parking lot 10 Low OF 27 Shawsheen River 3 0 2 1 1 0 3 0 2A_4 Drain south side of school 10 Low OF 28 Shawsheen River NA 3 0 2 1 1 0 3 0 2A_5 Drains childcare center parks 10 Low OF 29 Wetlands feeding Kiln

Brook NA 0 0 2 3 3 0 3 0 3 Drains multiple roads and facilities on east of Base 11 High

OF 30 Wetlands feeding Kiln

NA 0 0 2 3 2 0 3 0 3 Drains most of MIT area 10 Low OF 31 Wetlands feeding Kiln

NA 0 0 2 1 2 0 3 0 3 Drain roads off base 8 Low

OF 32 Wetlands feeding Kiln

NA 0 0 2 1 2 0 3 0 3 Drains small portion of off base road 8 Low OF 33 Wetlands exiting

Hanscom AFB to south NA 0 0 2 1 2 0 3 0 4 Drains southeast corner of base, maintenance shop, research buildings 8 Low

Scoring Criteria:

1 Previous screening results indicate likely sewer input if any of the following are true:

• Olfactory or visual evidence of sewage,

• Ammonia ≥ 0.5 mg/L, surfactants ≥ 0.25 mg/L, and bacteria levels greater than the water quality criteria applicable to the receiving water, or

• Ammonia ≥ 0.5 mg/L, surfactants ≥ 0.25 mg/L, and detectable levels of chlorine

2 Outfalls/interconnections that discharge to or in the vicinity of any of the following areas: public beaches, recreational areas, drinking water supplies, or shellfish beds 3 Receiving water quality based on latest version of MassDEP Integrated List of Waters.

• Poor = Waters with approved TMDLs (Category 4a Waters) where illicit discharges have the potential to contain the pollutant identified as the cause of the impairment

• Fair = Water quality limited waterbodies that receive a discharge from the MS4 (Category 5 Waters)

• Good = No water quality impairments

4 Generating sites are institutional, municipal, commercial, or industrial sites with a potential to contribute to illicit discharges (e.g., car dealers, car washes, gas stations, garden centers, industrial manufacturing, etc.)

5 Age/Type of development and infrastructure:

• High = Industrial areas greater than 40 years old, areas where the sanitary sewer system is more than 40 years old, and areas with SPCCPs

• Medium = Developments 20-40 years old

• Low = Developments less than 20 years old

6 Areas once served by combined sewers and but have been separated, or areas once served by septic systems but have been converted to sanitary sewers.

7 Aging septic systems are septic systems 30 years or older in residential areas.

8 Any river or stream that is culverted for distance greater than a simple roadway crossing. Hanscom AFB will included culverted wetland flow in this category.

9Problem outfall = Previous Screening Result indicating Sewer input. High Priority Outfall=Score greater than 11. Low Priority Outfall= Score less than 11. This scoring criteria may be updated annually by Hanscom AFB Stormwater Manager as new information becomes available.

Illicit Discharge Deterction and Elimination Program 17

6 Dry Weather Outfall Screening and Sampling Dry weather flow is a common indicator of potential illicit connections. The MS4 Permit requires all outfalls/interconnections (excluding Problem and Excluded Outfalls) to be inspected for the presence of dry weather flow within three years of the effective permit date (July 1, 2021).

Hanscom AFB will conduct dry weather outfall screening, starting with High Priority outfalls, followed by Low Priority outfalls in accordance with the procedure outlines in Attachment C and based on the initial priority rankings described in the previous section.

Outfalls 7-15 drain into a culverted section of the Shawsheen River running through the center of the MS4 area. At Outfall 7, 8, and 12 a manhole is present in the culvert in the location of the outfall. For these outfalls a sample will be taken from the culvert manhole. Flow will likely always be present due to stream flow and possible dilution of illicit discharge could occur. For this reason, further manhole investigation is important and will be prioritized for these drainage systems. Outfall 9, 10, 11, 13, 14 and 15 enter into the culverted stream section where no manholes are present. For these outfalls the nearest upstream manhole in the stormwater drainage system will be used for observation and sampling. These sampling manhole locations are indicated on Attachment B: Figure 1 and 2 and Table 5-1. If any outfall is inaccessible or submerged at time of sampling, the permittee may proceed to the first accessible upstream manhole in accordance this MA MS4 General Permit section 2.3.4.7 (b)(iii)(2).

Several outfalls in the Hanscom AFB drainage system drain both stormwater and naturally occurring wetlands. Due to this, flow may be observed at outfalls during dry weather which does not necessarily indicate an illicit discharge. When flow is observed at an outfall a sample will be collected in accordance with the procedures presented in Attachment C.

6.1 Weather Conditions

Dry weather outfall screening and sampling may occur when no more than 0.1 inches of rainfall has occurred in the previous 24-hour period and no significant snow melt is occurring. For purposes of determining dry weather conditions, program staff will use precipitation data from a local weather station. If the weather station is not available, a backup weather station will be used.

6.2 Performing Dry Weather Screening

Dry weather outfall screening and sampling will be performed in accordance with the procedures presented in Attachment C by trained Hanscom AFB personnel or qualified contractors. Checklist 1: Dry Weather Outfall Inspection Survey will be completed for all outfalls to record dimensions, shape, material, spatial location, physical condition, indicators of potential illicit discharges, and flow of the Outfall. If observable flow is noted, Checklist 2: Dry Weather Outfall Inspection Survey for Observable Flow will be completed. A sample will be collected from the Outfall flow and analyzed for ammonia, surfactants, chlorine, total

Illicit Discharge Deterction and Elimination Program 18 phosphorus (pollutant of concern), and indicator bacteria (E. coli). If no flow is observed, but evidence of illicit flow exists, Hanscom AFB will repeat the Dry Weather Screening within one week of initial observation. All sample gathering and laboratory analysis will comply with suggested U.S. EPA methods. The completed checklists will be stored in Attachment C of the IDDE Plan. Attachment C Table 4 will be used to track and annually report the dry weather screening status of all outfalls.

6.3 Interpreting Outfall Sampling Results

Outfall analytical data from dry weather sampling can be used to help identify the major type or source of discharge. Table 6-1 shows values identified by the U.S. EPA and the Center for Watershed Protection as typical screening values for select parameters. These represent the typical concentration or value of each parameter expected to be found in stormwater. Screening values that exceed these benchmarks may be indicative of pollution and/or illicit discharges.

Table 6-1. Benchmark Field Measurements for Select Parameters

Analyte or Parameter

Benchmark

Ammonia >0.5 mg/L Conductivity >2,000 μS/cm Surfactants >0.25 mg/L Chlorine >0.02 mg/L

(detectable levels per the 2016 MS4 Permit) Indicator Bacteria1:

E. coli Enterococcus

E. coli: the geometric mean of the five most recent samples taken during the same bathing season shall not exceed 126 colonies per 100 ml and no single sample taken during the bathing season shall exceed 235 colonies per 100 ml

Enterococcus: the geometric mean of the five most recent samples taken during the same bathing season shall not exceed 33 colonies per 100 ml and no single sample taken during the bathing season shall exceed 61 colonies per 100 ml

6.4 Follow-up Ranking of Outfalls and Interconnections

Hanscom AFB will update and re-prioritize the initial outfall and interconnection rankings in Table 5-1 based on information gathered during dry weather screening. The rankings will be updated periodically as dry weather screening information becomes available but will be completed within three years of the effective date of the permit (July 1, 2021).

Illicit Discharge Deterction and Elimination Program 19

Outfalls/interconnections where relevant information was found indicating sewer input to the MS4 or sampling results indicating sewer input are highly likely to contain illicit discharges from sanitary sources.

Such outfalls/interconnections will be ranked as Problem Outfalls for investigation. Other outfalls and interconnections may be re-ranked based on any new information from the dry weather screening.

1 Massachusetts Water Quality Standards: http://www.mass.gov/eea/docs/dep/service/regulations/314cmr04.pdf http://www.mass.gov/eea/docs/dep/service/regulations/314cmr04.pdf

Illicit Discharge Deterction and Elimination Program 20

7 Catchment Investigations Once stormwater outfalls with evidence of illicit discharges have been identified, various methods can be used to trace the source of the potential discharge within the outfall catchment area. Catchment investigation techniques include but are not limited to review of maps, historic plans, and records; manhole observation; dry and wet weather sampling; video inspection;

smoke testing; and dye testing. This section outlines a systematic procedure to investigate outfall catchments to trace the source of potential illicit discharges. All data collected as part of the catchment investigations will be recorded and reported in each annual report.

7.1 System Vulnerability Factors

Hanscom AFB will review relevant mapping and historic plans and records to identify areas within the catchment with higher potential for illicit connections. The following information will be reviewed:

• Plans related to the construction of the drainage network

• Plans related to the construction of the sewer drainage network

• Prior work on storm drains or sewer lines

• Board of Health (BOH) or other municipal data on septic systems

• Complaint records related to SSOs

• Septic system breakouts.

Based on the review of this information, the presence of any of the following System Vulnerability Factors (SVFs) will be identified for each catchment:

• History of SSOs, including, but not limited to, those resulting from wet weather, high water table, or fat/oil/grease blockages.

• Common or twin-invert manholes serving storm and sanitary sewer alignments.

• Common trench construction serving both storm and sanitary sewer alignments.

• Crossings of storm and sanitary sewer alignments where the sanitary system is shallower than the storm drain system.

• Sanitary sewer alignments known or suspected to have been constructed with an underdrain system.

• Inadequate sanitary sewer level of service (LOS) resulting in regular surcharging, customer back-ups, or frequent customer complaints.

• Areas formerly served by combined sewer systems.

• Sanitary sewer infrastructure defects such as leaking service laterals, cracked, broken, or offset sanitary infrastructure, directly piped connections between storm drain and sanitary sewer infrastructure, or other vulnerability factors identified through Inflow/Infiltration Analyses, Sanitary Sewer Evaluation Surveys, or other infrastructure investigations.

• Sewer pump/lift stations, siphons, or known sanitary sewer restrictions where power/equipment failures or blockages could readily result in SSOs.

Illicit Discharge Deterction and Elimination Program 21

• Any sanitary sewer and storm drain infrastructure greater than 40 years old.

• Widespread code-required septic system upgrades required at property transfers

(indicative of inadequate soils, water table separation, or other physical constraints of the area rather that poor owner maintenance).

• History of multiple Board of Health actions addressing widespread septic system failures (indicative of inadequate soils, water table separation, or other physical constraints of the area rather that poor owner maintenance).

A SVF inventory will be documented for each catchment (see Table 7-1), retained as part of this IDDE Plan, updated annually based on sampling dry, wet, and manhole sampling results and included in the annual report

Illicit Discharge Deterction and Elimination Program 22

Table 7-1. Outfall Catchment System Vulnerability Factor Inventory

Revision Date: May 2019

History of SSOs

Common or Twin Invert Manholes

Common Trench

Construction

Storm/Sanitary

Crossings (Sanitary Above)

Sanitary Lines with Underdrains

Inadequate

Sanitary Level of Service

Areas Formerly

Served by Combined

Sewers

Sanitary

Infrastructure Defects

SSO Potential in Event of System Failures

Sanitary and Storm Drain

Infrastructure >40 years Old

Septic with

Poor Soils or Water Table Separation

History of BOH

Actions Addressing

Septic Failure Sample 1 XYZ River Yes/No Yes/No Yes/No Yes/No Yes/No Yes/No Yes/No Yes/No Yes/No Yes/No Yes/No Yes/No

Presence/Absence Evaluation Criteria:

1. History of SSOs, including, but not limited to, those resulting from wet weather, high water table, or fat/oil/grease blockages

2. Common or twin-invert manholes serving storm and sanitary sewer alignments

3. Common trench construction serving both storm and sanitary sewer alignments

4. Crossings of storm and sanitary sewer alignments where the sanitary system is shallower than the storm drain system

5. Sanitary sewer alignments known or suspected to have been constructed with an underdrain system

6. Inadequate sanitary sewer level of service (LOS) resulting in regular surcharging, customer back-ups, or frequent customer complaints

7. Areas formerly served by combined sewer systems

8. Sanitary sewer infrastructure defects such as leaking service laterals, cracked, broken, or offset sanitary infrastructure, directly piped connections between storm drain and sanitary sewer infrastructure, or other vulnerability factors identified through

Inflow/Infiltration Analyses, Sanitary Sewer Evaluation Surveys, or other infrastructure investigations

9. Sewer pump/lift stations, siphons, or known sanitary sewer restrictions where power/equipment failures or blockages could readily result in SSOs

10. Any sanitary sewer and storm drain infrastructure greater than 40 years old

11. Widespread code-required septic system upgrades required at property transfers (indicative of inadequate soils, water table separation, or other physical constraints of the area rather that poor owner maintenance)

12. History of multiple Board of Health actions addressing widespread septic system failures (indicative of inadequate soils, water table separation, or other physical constraints of the area rat her that poor owner maintenance)

Illicit Discharge Deterction and Elimination Program 23

7.2 Dry Weather Manhole Inspections

Hanscom AFB will implement a dry weather storm drain network investigation that involves systematically and progressively observing, sampling and evaluating key junction manholes in the MS4 to determine the approximate location of suspected illicit discharges or SSOs.

Infrastructure information will be incorporated into the storm system map, and catchment delineations will be refined based on the field investigation, where necessary. The SVF inventory will also be updated based on information obtained during the field investigations, where necessary.

Several important terms related to the dry weather manhole inspection program are defined by the MS4 Permit as follows:

• Junction Manhole is a manhole or structure with two or more inlets accepting flow from two or more MS4 alignments. Manholes with inlets solely from private storm drains, individual catch basins, or both are not considered junction manholes for these purposes.

• Key Junction Manholes are those junction manholes that can represent one or more junction manholes without compromising adequate implementation of the illicit discharge program. Adequate implementation of the illicit discharge program would not be compromised if the exclusion of a particular junction manhole as a key junction manhole would not affect the permittee’s ability to determine the possible presence of an upstream illicit discharge. A permittee may exclude a junction manhole located upstream from another located in the immediate vicinity or that is serving a drainage alignment with no potential for illicit connections.

For all catchments identified for investigation, during dry weather, field crews will systematically inspect key junction manholes for evidence of illicit discharges. This program involves progressive inspection and sampling at manholes in the storm drain network to isolate and eliminate illicit discharges.

The manhole inspection methodology will be conducted in one of two ways (or a combination of both):

• By working progressively up from the outfall and inspecting key junction manholes along the way, or

• By working progressively down from the upper parts of the catchment toward the outfall.

For most catchments, manhole inspections will proceed from the outfall moving up into the system.

However, the decision to move up or down the system depends on the nature of the drainage system and the surrounding land use and the availability of information on the…