EPA
Onsite
Wastewater
Management
Steps:
- Map
- Design
- Maintain
- Regulate
United States
Environmental
Protection Agency
Region 9 Ground Water
Office (WTR-9)
EPA 909-F-04-007
JULY 2004
ground
surface
settling occurs in
one or more
compartments of
the septic tank
Tribal Management of Onsite
Wastewater Treatment Systems
To protect public health and water quality, states and local governments across North
America establish regulations for the safe and appropriate use of OWTS. OWTS can
provide effective sewage treatment, if sited in suitable soils, and constructed and operated
properly. This guidance document is intended to help tribal nations determine what level
of management or tribal regulation will work best to ensure public health and protect the
environment.
What is onsite wastewater treatment?
Any sewage treatment process that removes contaminants from wastewater at or near
the point of generation, with dispersal of fluid nearby, is considered "onsite", whether it
serves a single-family residence, a restaurant, an office building or a major resort. The
most common type of onsite wastewater treatment system is the septic system. Onsite
wastewater treatment is also called decentralized wastewater treatment, to distinguish it
from centralized treatment (at municipal sewage treatment plants.)
A typical septic system contains the two major components pictured at left: a water-tight
septic tank and an absorption field, also known as a drain field or leachfield.
The purpose of the septic tank (see diagram below) is to separate solids from the liquid
waste, and to promote breakdown of contaminants by microorganisms (bacteria) naturally
present in wastewater. The wastewater breaks down into a layer of solids that sink, a
liquid layer (which is mostly water) and a scum layer that floats. The septic tank slows and
stabilizes the rate of flow to allow this decomposition. Septic tanks should be able to
accomodate at least 2-3 days of average flow for adequate detention time. Solids and
scum need to be removed by a professional septic tank pumper on a regular basis
(approximately every 1 to 5 years, depending on the size of the tank and number of people
using it). The liquid layer flows through the outlet of the septic tank to an absorption area.
As the liquid waste contacts air and microbes in the soil, treatment of pathogens can
occur. Some of the liquid can evaporate, and some percolates down to the water table. In
some areas where the depth to ground water is very great, seepage pits (which are
sometimes mistaken for cesspools) are allowed to be used instead of
a leachfield. In other areas where soils cannot provide adequate
treatment, or do not drain at a rate that allows for treatment, additional
treatment or dispersal technologies may be required. Many of these
components, such as sand or peat filters, work by replacing what is
missing from the soil environment.
Knowing the output of a conventional septic system in your local
soils is the key to understanding how and if OWTS might pose a
public health risk. The risk grows with the population. Increasing
population density increases the contaminants, such as nitrogen,
entering the environment through wastewater. What can a tribe do to
manage these systems, while maximizing water use efficiency and
ground water recharge, and minimizing risks to public health and the
environment? The following pages provide an approach to this
question.
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Step 1: Map
The location of all the onsite wastewater treatment
systems (OWTS) on the reservation should be mapped
and kept in a permanent file. The file could also include
global positioning system (GPS) coordinates, narrative
descriptions relative to permanent structures,
handwritten maps, etc. In order to easily locate septic
tanks and drainfields, their physical location should be
marked in the field with a note in the file regarding the
type of marker (such as risers). In addition, the name
and contact information of the residents and owners for
all OWTS on the Reservation should be kept in the file.
Pursuant to the Underground Injection Control (UIC)
regulations at 40 CFR §144.26, inventory forms are
required to be completed by the owners of all community
(or large capacity) OWTS that discharge subsurface.
Additional information, or in some cases a permit, may
also be required. A community, or large capacity, septic
system is one that treats the sanitary waste of 20 or
more people per day. Therefore, the number of users
for each system should be counted to check for UIC
applicability. Systems discharging to surface waters are
subject to requirements of the Clean Water Act.
Federal Regulatory Terms
(40 CFR part 144.3)
Cesspool means a "drywell"that receives untreated sanitary waste
containing human excreta, and which sometimes has an open
bottom and/or perforated sides. BANNED > 20 PERSONS
Sanitary waste means liquid or solid wastes originating solely from
human activities, such as wastes collected from toilets, showers,
wash basins, sinks used for cleaning domestic areas, sinks used
for food preparation, clothes or dish washing operations. Sources
of these wastes may include single or multiple residences, hotels
and motels, restaurants, bunkhouses, schools, ranger stations,
crew quarters, guard stations, campgrounds, picnic grounds, day-
use recreation areas, other commercial facilities, and industrial
facilities provided the waste is not mixed with industrial waste.
Septic system means a "well" that is used to emplace sanitary
waste below the surface and is typically comprised of a septic tank
and subsurface fluid distribution system or disposal system.
l/l/e//means: A bored, drilled, or driven shaft whose depth is greater
than the largest surface dimension; or, a dug hole whose depth is
greater than the largest surface dimension; or, an improved
sinkhole; or, a subsurface fluid distribution system.
The hydrogeologic conditions under all OWTS must be
known in order to protect the reservation's ground water
resources. Therefore, the seasonal ground water
elevation, ground water flow direction, geologic layers,
and the location of all drinking water wells around all
OWTS should be inventoried. Knowing this information
will help determine the likelihood of contaminants
traveling from the soil surface (or drainfield area) to the
next downgradient water body (surface or ground water.)
This step provides an excellent opportunity to educate
the residents and owners about how OWTS work as
well as what maintenance activities are needed on a
regular basis.
Step 2: Design
The design of all new OWTS should be approved by an
appropriate tribal environmental program prior to any
construction. In addition, the design of all new large
capacity OWTS should be reviewed by EPA (see
contacts list on last page.) At a minimum, the design
should account for soil characteristics (based on soil
evaluation or percolation test and profile), ground water
elevation and flow direction, expected wastewater flow
(estimated from the number of users), septic tank
volume, and absorption area and type of drainfield. For
proper and efficient maintenance, large diameter risers
should be installed on the septic tank access ports.
These large diameter risers eliminate the need to locate
and dig down to the septic tank access ports for each
maintenance effort. Observation ports (usually 4 inch
diameter PVC risers) should be present on the ends
and/or corners of the drainfield lines to properly monitor
the drainfield operation. No driving, parking, heavy foot
traffic, or watering should be allowed on the drainfield.
OWTS design should be completed by a licensed
professional following an approved set of design
standards. To reduce the workload required for this effort,
the nearest State or County OWTS design standards
(which take the local hydrogeologic conditions into
account) might be considered for adoption until tribal
standards are developed.
Step 3: Maintain
To ensure proper wastewater treatment and ground
water protection, an operation and maintenance
schedule for each OWTS should be established and
followed. All operators should be properly trained in order
to properly carry out the maintenance schedule. (See
EPA Region 9 Recommended OWTS Management Guidelines for Native American Tribes, page 2 of 4
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Training providers box, page 4.) The maintenance
schedule should include:
a. Regular monitoring of the
sludge and scum layers in all
chambers of the septic tank.
The septic tank should be
pumped when the thickness
of the sludge layer and the
scum layer exceeds 1/3 of
the septic tank's total height.
Failure to pump a septic
system will result in solids
flowing out to the drainfield,
which will clog the soil pores
and cause drainfield failure.
The cost of pumping a septic tank on a regular basis is
small relative to the cost of replacing a drainfield.
b. Monitoring the condition of the drainfield for standing
water on the soil surface, standing water in the
observation ports, erosion, and areas of massive plant
growth. Massive plant growth is an indicator of: 1) leaks
(if massive plant growth is only in one small area of the
drainfield) and/or 2) subsurface mounding of septic
tank effluent resulting from an undersized or clogged
drainfield (if the massive plant growth is throughout the
drainfield or in the area of lowest elevation).
Also, automobiles and other heavy equipment should
be prevented from driving and/or parking on the
drainfield.
All maintenance activities performed on OWTS
should be kept on record. This record is suggested to
be a notebook that includes: OWTS construction
drawings ("as-builts") and design capacities, standard
worksheets which are filled in and signed and dated by
the owner/operator(s) as maintenance occurs, analytical
test results, pumping company statements, and
summaries of any problems and how they were resolved.
The date the drainfields are switched (if alternating
drainfields are utilized for an OWTS) should also be
included in the maintenance schedule and documented
in the record.
Whether the tribe, the system owner, or a third party is
responsible for maintenance, the system will not function
if the system owner does not know that the OWTS is
there. Workshops, radio announcements, or messages
in water bills are some of the ways the tribe might inform
system owners of OWTS operation. At a meeting several
years ago, someone suggested linking OWTS
management fees to cable television service fees as
one means of insuring system owner compliance.
Step 4: Regulate
Developing and incorporating the OWTS Management
Guidelines into ordinances is the final, and perhaps the
most important step in protecting the tribe's drinking
water aquifers from sewage contamination. This step
will establish a uniform standard for OWTS management
throughout the reservation. Without establishing
ordinances, efforts invested in developing an OWTS
management program can be lost overtime as leadership
changes. Sustainable growth and a healthy population
depends on clean water supplies.
If you decide to establish an OWTS management
program, funding to support your effort may be available
through EPA or through the USDA Rural Utilities Service
in the form of loans or grants.
More detailed information can be found in the Voluntary
National Guidelines for Management of Onsite and
Clustered (Decentralized) Wastewater Treatment
Systems, with examples in a separate management
handbook. These documents and others, including
homeowner educational materials can be downloaded
from www.epa.aov/owm/mtb/decent/index.htm.
CENTRALIZED OR DECENTRALIZED TREATMENT?
CENTRALIZED
benefits:
Stabilized waste stream and
high volume treated effluent
available for reuse
Centralized maintenance and
operation
Treatment upgrades to
address "new" contaminants
are also centralized
Considerations:
Higher capital costs
Bigger risk from spill or leaks
Users still need to connect
DECENTRALIZED
benefits:
Onsite recharge/reuse
Lower capital costs
o long-distance pipelines
Considerations:
Need to maintain
access for O&M
Soil and aquifer
characteristics, housing
density may change over
time, decreasing peformance
Advanced treatment and
monitoring can be costly
EPA Region 9 Recommended OWTS Management Guidelines for Native American Tribes, page 3 of 4
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Onsite sewage management
resources:
EPA onsite wastewater page:
http://cfpub.epa.gov/owm/septic/home.cfm
Homeowner maintenance checklist:
www.epa.gov/owm/septic/pubs/septic sticker.pdf
Large capacity septic (UIC) inventory form:
www.epa.gov/safewater/uic/pdfs/7520-16.pdf
TRIBAL WASTEWATER EVALUATION: available for
tribes within EPA Region 9, by calling (415) 972-3544
or 972-3531, or through our partnership with the
Rural Community Assistance Corporation, (760) 492-
2543.
For tribes outside of Region 9, please consult
www.epa.gov/indian/map.htm for the area contact.
Onsite Sewage Training Options
in the Southwest
Technical information about onsite wastewater treatment
options is available free or at low cost from the National Small
Flows Clearinghouse, (800)624-8301 Eastern Standard Time,
www.nsfc.wvu.edu. Training is available from several sources,
such as any of the training centers listed:
SELF STUDY: California State University, Office of Water
Programs correspondence training, CSU-Sacramento, (916)
278-6142, www.owp.csus.edu/wastewater.htm
FIELD EDUCATION: California WastewaterTraining and
Research Center, CSU-Chico, (530) 898-6027,
www.csuchico.edu/cwtrc
Northern Arizona University Onsite Wastewater
Demonstration Facility, NAU-Flagstaff, (520) 523-4330,
www.cet.nau.edu/wdp/
University of Arizona Extension, Yuma Ag. Center
(520) 782-3836, http://aq.arizona.edu/waterquality/
OWTFPaqe.htm
DISCLAIMER: The statements in this document are intended solely as guidance. This document is not intended, nor can it be relied upon, to create any
rights enforceable by any party in litigation with the United States. This guidance may be revised without public notice to reflect changes in EPA's approach
to implementing the authorities discussed in the document or to clarify and update text.
U.S. Environmental Protection Agency, Region 9
Underground Injection Control Program (WTR-9)
75 Hawthorne Street
San Francisco, California 94105- 3109
OFFICIAL BUSINESS - PENALTY FOR PRIVATE USE $300
FIRST CLASS MAIL
U.S. POSTAGE
PAID
U.S. EPA
Permit No. G-35
A healthy, well-
maintained and
appropriately sized septic
tank will generally require
less pumping over its
service life, saving time
and money.
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