The Arizona Administrative Code Title 18 (AAC R18-9), Water
Pollution Control, covers wastewater permitting under the Aquifer
Protection Permitting (APP) process with the purpose of protecting
groundwater from degradation.
Click here to read more.
Permits are broken down into individual permits and general permits.
General Permits cover sewer collection systems including pipes and
lift stations, and treatment and disposal systems (on-site
wastewater) for one house or business. A new or upgrade to a
wastewater treatment plant serving more than one house or business
requires an individual permit. These types of individual permits are
reviewed and approved by the Arizona Department of Environmental
Quality (ADEQ). An individually owned wastewater system generating
more than 24,000 gallons per day also requires an individual permit.
These permits may be reviewed by ADEQ or the County depending on the
Mills Engineering is familiar with the state regulations and can
help you determine how your project can comply with the
requirements, the permitting costs, and help you through the
ADEQ has delegated various Counties different aspects of the
review of wastewater systems. The delegation agreements are
available at the ADEQ website for review.
Click here to read more.
Mills Engineering can help you determine who will review your
project, the requirements of the agency, and help you meet their
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On-site Wastewater/Septic Systems
New Construction, The steps for your septic system project
1. Site and soils Evaluation by the regulatory agency (Phase 1) or
Mills Engineering to determine if there are any limiting conditions
present or if a sewer system connection is within 400 feet and
2. Notice of Intent to Discharge (NOID) application
Design of the system by Mills Engineering based on building and site
plan and limiting conditions: Residential: number of bedrooms and
number of fixture units; Commercial: based on use and wastewater
generation rates and plumbing fixtures
3. Construction Authorization (CA) – County or state approves the
4. Construction of the system by contractor followed by review of
the installed system
5. Discharge Authorization (DA) – After construction and review by
the county or designer, system is authorized to operate by the
regulatory agency. For alternative treatment systems, a contract
with a certified operator may be required.
If the house changes include a change in the number of plumbing
fixtures and/or bedrooms, the existing septic system will likely
require expansion or replacement. Soil evaluation and design
followed by filing the NOID will be required. The records of the
system may be found by contacting your county health department.
Septic systems may fail for a number of reasons: age, soil
plugging from salts build up, improper maintenance, damage, etc.
Replacement of the entire system requires the steps shown above for
new construction. For alterations or repairs, a smaller fee is
charged, but the same process as new construction is followed.
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Local and Regional Wastewater Systems
Gravity Sewer System, Lift Station, and pressurized force main
The steps to permit a larger project include:
Connection to existing system, authorized by the owner with enough
capacity in the pipes, treatment plant, and disposal system
1. Notice of Intent to Discharge (NOID) application: The application
and construction plans showing design of the system, specifications,
a design report, authorization from the owner if you are connecting
to another system, and draft Operation and maintenance manual are
required. Mills Engineering can help you by designing the system and
writing the reports and draft manual.
2. Construction Authorization: The regulatory agency reviews the
NOID and requests more information or approves the design.
3. System is constructed and operation and installation are reviewed
by Mills Engineering. An Engineer’s Certificate of Completion is
submitted to the regulatory agency with test results.
4. Discharge Authorization: The regulatory agency reviews the
certificate and may visit the project before issuing the DA that
authorizes operation of the completed system. For most larger
projects that do not become part of an existing system, a certified
operator will be required to oversee the operation.
Wastewater Treatment Plant or Treatment Plant Expansion
208 Plan Small Plant Review or Amendment
The permitting process that is required to expand a wastewater
treatment facility or construct a new one includes the 208 Amendment
or Small Plant Review. The concept for the plant must follow the 208
Plan, a regional wastewater plan to protect the environment,
following Section 208 of the Clean Water Act. The state of Arizona
is divided into different regions with a governmental agency
overseeing the 208 plan in each region. Some examples are the
Central Arizona Association of Governments, Maricopa Association of
Governments, and Pima Association of Governments. Members of the
associations are representatives of local governments. The
associations review the changes to the 208 plan to oversee regional
The first step for a 208 Plan Amendment or Small Plant Review is to
complete a Design Concept Report and 208 Report detailing the scope
of the project. This document is reviewed by neighboring communities
and the community that will submit it to the association for review.
After approval by neighboring communities, the association will
review the document followed by the Arizona Department of
Environmental Quality and Environmental Protection Agency.
Once the plant has been approved by the government association,
detailed Design of plant and sewer system will continue.
Construction plans and specifications and a draft operation and
maintenance manual are prepared for review by the delegated County
or Arizona Department of Environmental Quality (ADEQ).
Aquifer Protection Permit
An Individual Aquifer Protection Permit Application is also
submitted to ADEQ, who reviews it for Administrative Completeness,
Technical Completeness, issues a Draft Permit, gives Public Notice,
and issues a final permit.
Certificate of Completion and Discharge Authorization
Once the plant is constructed, operation and installation are
reviewed by Mills Engineering. Once all punch list items are
addressed, the Engineer’s Certificate of Completion is submitted to
the regulatory agency along with test results.
The agency reviews the submittal and may visit the installation
before issuing the Discharge Authorization. The final APP permit and
208 Plan approval is required before operation can begin. The
operation and startup of the plant follows.
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The Arizona Administrative Code Title 18 (AAC R18-4 and 5,
Article 5), Safe Drinking Water and Environmental Reviews and
Certification, cover water system permitting with the purpose of
providing safe drinking water for public consumption.
Click here to read more:
Mills Engineering is familiar with the rules for water system design
and compliance and can help you plan and complete your water system.
The permitting process consists of:
1. Submitting an application for Approval to Construct (AtC) with
the design report, construction plans and specifications, draft
operation and maintenance manual and water quality sample results,
if needed. Mills Engineering can design the system and submit the
permit application to the delegated agency.
2. Review by the regulatory agency and issuance of the Approval to
3. Construction of the system and review of the installation and
operation by Mills Engineering. Sample testing for verification of
disinfection or required treatment.
4. Submitting the Engineer’s Certificate of Completion, final O and
M manual and Application for Approval of Construction (AoC) to the
5. Review by the regulatory agency and issuance of the Approval of
Construction. A certified operator will be required to oversee it if
it is a community water system.
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