GREEN INFRASTRUCTURE PERMITTING AND ENFORCEMENT SERIES: FACTSMEET 3
Depending on the causes of sanitary sewer overflows
fora particular system, green infrastructure
approaches may be used in conjunction with  "
measures to help eliminate overflows.
                                                                              United States
                                                                              Environmental Protection
                                                                              Agency

                                                                              EPA832F12014

   Sanitary  Sewer  Overflows

               This factsheet is the third in a series of six on integrating green
                    infrastructure concepts into permitting, enforcement, and
                                       water quality standards actions.
Introduction
CMOM or Remedial Measures
Plan Components
                                                                         Consent Decree Components

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Integrating Green Infrastructure Concepts into
Permitting, Enforcement, and Water Quality
Standards Actions

This factsheet is the third in a series

of six factsheets in the U.S. EPA Green

Infrastructure Permitting and Enforcement

Series (http://water.epa.gov/infrastructure/

greeninfrastructure/gi_regulatory.

cfm#permittingseriesA This series

describes how EPA and state permitting and

enforcement professionals can incorporate

green infrastructure practices and approaches

into National Pollutant Discharge Elimination

System (NPDES) wet weather programs,

including stormwater permits, Total

Maximum Daily Loads (TMDLs), combined

sewer overflow (CSO) long-term control

plans (LTCPs), and enforcement actions.

This series builds upon EPA's continued

investment in green infrastructure and low

impact development. Existing EPA authority,

guidance, and agreements enable EPA

Regions and state agencies to work with

permittees to include green infrastructure

measures as part of control programs.
For additional resources on green infrastructure,
go to the EPA Green Infrastructure Web
page: http://water.epa.gov/infrastructure/
greeninfrastructure/index.cfm.

Key green infrastructure guidance issued
to date can be found at: http://water.epa.
gov/infrastructu re/green infrastructure/
gLpolicy.cfm.
Introduction

Properly designed, operated, and maintained sanitary
sewer systems are meant to collect and transport all of the
sewage that flows into them to a publicly owned treatment
works (POTW). However, in some communities under some
circumstances discharges of raw sewage from municipal
sanitary sewers may occur.  These types of discharges
are called sanitary sewer overflows (SSOs). SSOs may
be attributable to blockages in the system or mechanical
failure such as a lift  station power outage. In addition,
SSOs often occur because of excessive "l&l" - infiltration
of water into collection systems and inflow. In the  context
of SSOs, infiltration means stormwater or groundwater
that seeps into the sewer system through cracks and
other vulnerable locations in the pipes and joints. Inflow
is the introduction of stormwater into the sanitary sewer
system via specific storm connections, either deliberate or
inadvertent. Common sources of inflow are the connection
of roof downspouts or discharges from sump pumps to the
sanitary sewer system.
Where there is excessive l&l of rainwater and/or
groundwater into the sanitary sewer system, the system
may become overloaded and overflow. All flows in sanitary
sewer systems need to be transported to treatment
plants and treated in accordance with NPDES permit
requirements.  EPA guidance on SSOs can be found here:

    PERMITTING: http://cfpub.epa.gov/npdes/home.
    cfm?program_id=4
    ENFORCEMENT: http://cfpub.epa.gov/compliance/
    resources/policies/civil/cwa/


Grey infrastructure improvements/expansions and
implementation of a  capacity, management, operations and
maintenance (CMOM) or remedial measures program are
among the traditional approaches used to bring separate
sanitary systems into compliance with the Clean Water
Act. Depending on the causes of SSOs for a particular
system, green  infrastructure approaches may be used
in conjunction with grey  infrastructure improvements
and CMOM to help eliminate SSOs. Green infrastructure
may help by keeping some wet weather flows out of the
separate sewer system.

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GREEN INFRASTRUCTURE PERMITTING AND ENFORCEMENT SERIES: FACTSMEET 3
 Green infrastructure approaches may be ideal solutions
 for inflow problems. They are preventive measures rather
 than treatment measures, and eliminate or reduce the
 need to create additional capacity in the sewer system by
 keeping water out of the system. Disconnecting sources
 of stormwater to sanitary sewer systems should be a high
 priority for any SSO abatement program. Downspouts
 and other stormwater conveyances should not simply
 be rerouted to storm sewer systems as that is simply a
 transfer of the water quality problems from one system to
 another. Instead these sources should be routed to rain
 barrels, cisterns, rain gardens, swales or other measures
 where the stormwater can recharge groundwater, irrigate
 landscapes, or serve other non-potable water needs.
 A number of communities have successfully instigated
 downspout disconnection programs to keep water out of
 sewer systems (sanitary, combined and storm). In these
 situations rainwater is typically directed to vegetated areas
 where stormwater can be infiltrated and evapotranspired,
 or directed to  water harvesting devices.
   For examples of municipal downspout
   disconnection programs see:

   http://water.epa.gov/infrastructure/
   greeninfrastructure/gi_what.cfm#downspout


When infiltration of water into the sanitary sewer system is
the primary problem, the most effective solution is typically
sanitary sewer rehabilitation. In the interim, reducing the
amount of groundwater and stormwater near the laterals
and joints that may be allowing water into the pipes may
be a goal. In this particular situation green infrastructure
approaches are still valuable, but there are important
considerations:  1) Practices that encourage infiltration of
stormwater into the  ground should be located away from
laterals where 'leaky' systems are identified or suspected;
and 2) placement of trees relative to pipes,  especially older
or 'leaky' pipes, should be carefully considered in order to
avoid root growth into joints.
 CMOM  or  Remedial Measures Plan Components
 As noted, a CMOM program may bean important tool for
 preventing SSOs and bringing sanitary sewer systems
 into compliance with the Clean Water Act. The following
 sections discuss how CMOM plans can be adapted to
 accommodate green as well as grey infrastructure.
 Capacity Estimates:  Green infrastructure may reduce the
 capacity improvements required to prevent SSOs. The
 process of estimating the capacity improvements  required
 for plans that include green infrastructure may be divided
 into two steps. The first step is to estimate the volume
 of water that can be kept out of the system, based on
 estimates of the collective capacities of distributed green
 technologies. The second step consists of fairly standard
 hydraulic modeling of the system. This step is required

 •X
regardless of the type of technologies in use, in orderto
determine discharge reductions at respective outfalls or
overflow points.
In general, estimating the impact of distributed controls
located throughout a sewershed on accumulated flow at a
discharge point can be more complicated than estimating
the impact of a single control atone location (e.g., as with
CSOs, where one central tunnel or basin may be used to
enhance capacity). However, in the case of SSOs, modeling
green technologies may not differ very much from modeling
more traditional technologies since reducing inflow is
traditionally accomplished through the removal of many
individual sources to the system.
                                                        CMOM or Remedial Measures Plan Components
                                                        •  Capacity estimates
                                                        •  Legal authority
                                                        •  Maintenance
                                                        •  Monitoring
                                                        •  Mapping/tracking

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Legal Authority:  Reduction of inflow through the use of
green infrastructure may present novel legal issues when
these controls are located on privately owned land. Where
bioinfiltration cells or other structures are installed on
private property, maintenance agreements, local ordinance
or other enforceable mechanisms will be required to
allocate legal responsibility for proper operation and
maintenance of the control measures.

Maintenance: As discussed above, green infrastructure
controls may be located on private property. For these
practices, legal mechanisms and institutional arrangements
typically need to be in place to ensure proper maintenance.
The community may want to establish education programs
or simple guidance materials for maintenance of green
infrastructure practices that will be maintained by private
property owners or operators.

When practices are located on public lands or within
public rights-of-way, the municipal operator should
establish standard operating procedures for maintenance
that include schedules, and procedures for maintenance,
reporting and tracking.
                                                          Monitoring: Monitoring provisions for green and grey
                                                          infrastructure solutions should be very similar. Documenting
                                                          performance of individual control measures typically is
                                                          not necessary as part of a monitoring program; a solid
                                                          maintenance program will ensure long-term function. Since
                                                          the goal of the SSO abatement program  is to reduce flows
                                                          into the system and overflows out of the system, variables
                                                          that address those objectives (e.g., in-pipe flow monitoring
                                                          or tracking of volume and frequency of overflows) maybe
                                                          appropriate metrics. In cases where green infrastructure to
                                                          reduce inflow is a major part of the overall SSO reduction
                                                          strategy, monitoring similar to that recommended in the CSO
                                                          context would also be appropriate.

                                                          Mapping/Tracking: As relevant, mapping or otherwise
                                                          identifying the locations of control measures (whether grey
                                                          or green) is important for when maintenance is required
                                                          and performed. See case study below.


                                                             CMOM guidance is provided in this document:

                                                             http://www.epa.gov/npdes/pubs/cmom_guide_
                                                             for_collection_systems.pdf
                                               SANITARY SEWER OVERFLOWS: Or.O1.'2012 - 05-31.2012
State of California Case Study
As an example, the State of California has
established procedures concerning monitoring
and mapping. All collections systems in California
must report their sanitary sewer overflows in
accordance with State Water Resources Control
Board, Order No. 2006-0003-DWQ, Monitoring and
Reporting Program, Statewide General Waste
Discharge Requirements for Sanitary Sewer
Systems, issued May 6,2006, and amended by
State Water Resources Control  Board Order No.
WQ 2008-0002-EXEC on February 20, 2008. Each
collection system must enroll for coverage under
this Order and register with the  online reporting
database. Enrollees must report the details of
each spill to the database, providing information
which includes: date of SSO, whether it reached
surface water, total volume, total volume
recovered, total volume reaching surface water,
location of the spill, time the agency was notified,
time the operator arrived, time the spill ended, actions taken to stop the SSO and perform clean-up activities, and planned future
actions for that site. The database is publicly accessible, and users can search for and view reported SSOs statewide by Street
Address, County, Responsible Agency, Spill Start & End Dates, Water Board Region, and Spill Category. The State Board has
launched a web-based GIS mapping tool  using Google Earth base maps for plotting all SSOs and private lateral spills in the State.

Links to the California order, database and mapping tool, fact sheets, and other information are at:  http://www.waterboards.
ca.gov/water_issues/programs/sso/index.shtml#general

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GREEN INFRASTRUCTURE PERMITTING AND ENFORCEMENT SERIES: FACTSMEET 3
 Consent Decree  Components

 Green infrastructure approaches may be a useful
 component of judicial consent decrees entered in Clean
 Water Act enforcement actions to resolve SSO violations.
 An SSO decree providing for green infrastructure may
 include the following concepts:
 The Collection System and Waste Water Treatment Plant
 (WWTP) Remedial Measures Plan should identify all
 measures necessary to achieve adequate capacity. If
 green infrastructure is proposed as a solution to reduce
 system capacity demands, it should be identified in this
 Plan. The Plan shall include specific metrics that can be
 measured and quantified on a continuous basis. If green
 infrastructure is used, the operator shall demonstrate
 appropriate legal authority to ensure adequate operations
 and maintenance.
 The reporting provisions of a consent decree or
 administrative order contain numerous specific provisions.
    Green infrastructure approaches may be a useful
    component of judicial consent decrees entered in
    Clean Water Act enforcement actions to resolve
    SSO violations.

As with other reporting requirements, a summary that
quantifies the effectiveness of all measures, including
green infrastructure measures, should be included.
Should evaluation of metrics indicate that green
infrastructure measures are not providing the anticipated
flow volume reductions to the sanitary sewer system, the
Plan should identify additional actions consistent with
meeting the SSO abatement objectives.

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                                                               By disconnecting downspouts and routing stormwater flows to swales,
                                                              rain gardens, or other green infrastructure measures, the need to create
                                                                additional capacity in the sewer system can be significantly reduced.
Green Infrastructure Permitting and Enforcement Series
This series on integrating green infrastructure concepts into
permitting, enforcement, and water quality standards actions
contains six factsheets plus four supplemental materials
that can be found at http://water.epa.gov/infrastructure/
greeninfrastructure/gi_regulatory.cfm#permittingseries.
Factsheets
1. Potential Challenges and Accountability Considerations
2. Combined Sewer Overflows
3. Sanitary Sewer Overflows
4. Stormwater
5. Total Maximum Daily Loads
6. Water Quality Standards

Supplemental Materials
1. Consent Decrees that Include Green Infrastructure Provisions
2. Consent Decree Language Addressing Green for Grey
  Substitutions
3. Green Infrastructure Models and Calculators
4. Green Infrastructure in Total Maximum Daily Loads (TMDLs)
United States
Environmental Protection
Agency
For additional resources on green infrastructure,
goto the EPA Green Infrastructure Web page:
http://www.epa.gov/greeninfrastructure/.

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