Current through Register Vol. 41, No. 3, September 23, 2024
A. Number and
general location of regional treatment plants.
1. The number of high-performance regional
plants which shall be permitted in this watershed is not more than three, but
preferably two, generally located as follows:
a. One plant in the Fauquier County/Warrenton
area.
b. One plant in the Manassas
area to serve the surrounding area in Prince William, Fairfax, and Loudoun
counties.
2. All point
source discharges of treated sewage effluent will preferably be located at
least 20 stream miles above the Fairfax County Water Authority's raw water
intake. In no case shall a plant be located less than 15 miles above the raw
water intake.
3. The provisions of
9VAC25-410-20 A 1 and A 2 shall not limit the consideration of land disposal
systems for waste treatment in the watershed, provided such systems shall have
no point source discharge to state waters and shall have the approval of the
Department of Environmental Quality (department).
B. Regional plant capacity allocations for
the Occoquan basin.
1. The initial allotment
of plant capacity for the Upper Occoquan Service Authority treatment facility
was approximately 10 MGD, based on all effluent being from high-performance
plants meeting the requirements of subsections D, E, and F of this section and
all those treatment facilities belonging to the City of Manassas, the City of
Manassas Park, the Greater Manassas Sanitary District, and Sanitary District 12
of Fairfax County being abandoned.
2. Incremental increases in the regional
plant capacity may be approved by the department based on the results of a
monitoring program that shows that current and projected discharges from the
high-performance plants do not create a water quality or public health problem
in the reservoir. The department advises that since severe infiltration/inflow
stresses the performance reliability of the regional treatment plants,
jurisdictions must pursue I/I correction within their individual
systems.
C.
Prerequisites for preliminary plant approval. Prerequisites before the
department gives approval to preliminary plans for a regional high-performance
plant are:
1. A monitoring program for the
receiving waters shall be in effect; and
2. The authority who is to operate the
proposed plant shall enter into a written and signed agreement with the
department that the authority shall meet the administrative requirements of
subsection F of this section.
D. Design concept for high-performance plants
on the Occoquan.
1. Plant design requirements
are:
a. The design of the high-performance
sewage treatment plants discharging to the Occoquan Watershed shall meet all
the requirements specified here as well as those specified in the most recent
edition of the Sewage Collection and Treatment Regulations (9VAC25-790-10 et
seq.); and
b. The basic sewage
plant design concept for the regional plants discharging to the Occoquan
watershed shall be based on the Upper Occoquan Service Authority Wastewater
Reclamation Facility.
2.
Changes in plant design requirements will be made according to these criteria:
a. Changes to the plant design described here
shall only be acceptable if the change does all of the following:
(1) Improves or equals the plant performance
and final effluent quality;
(2)
Increases or equals plant reliability and maintainability; and
(3) Has a demonstrated performance in a plant
of at least five to 10 MGD size for an operating period of not less than one,
but preferably two years.
b. Before such changes are incorporated in
the plant, specific written approval shall be obtained from the department;
and
c. Changes to the plant design
solely to reduce cost and which jeopardize plant performance and reliability
will not be approved.
E. Plant performance requirements.
1. The plant performance requirements for
high performance plants discharging to the Occoquan watershed are given in
Table I.
2. Operation of the
nitrogen removal facilities is required when the ambient nitrate concentration
(as N) is 5.0 mg/l or higher in the Occoquan reservoir in the vicinity of the
Fairfax County Water Authority intake point. The owner of the regional sewage
authority is responsible for knowing ambient results of nitrate and when
operation of nitrogen removal facilities is necessary.
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TABLE I
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MINIMUM EFFLUENT QUALITY REQUIREMENTS* FOR ANY
REGIONALSEWAGE TREATMENT PLANT IN THE OCCOQUAN WATERSHED
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FINAL EFFLUENT REQUIREMENTS
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COD mg/1 - 10.0
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Suspended solids mg/1 - 1.0
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Nitrogen mg/1 - 1.0**
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Phosphorus mg/1 - 0.1
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MBAS mg/1 - 0.1
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Turbidity NTU - 0.5***
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Coliform per 100 ml Sample - less than 2.0
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*As measured on a monthly average unless otherwise
noted. Since these are minimum requirements, the normal average would be
expected to be substantially better.
**Unoxidized nitrogen (as TKN) Refer to 9VAC25-410-20
E 2 for further information.
***Measured immediately prior to chlorination.
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F. Administrative and technical requirements
for the control of the sewer system tributary to a regional, high-performance
plant in the Occoquan watershed.
1. The owner
to whom the permit is issued for operation of a regional plant shall meet the
general and administrative requirements covered below. These requirements shall
also be contractually passed on by the owner to any parties or jurisdictions
with which the owner may contract for the processing of wastewater.
These requirements are applicable to regional sewage
treatment plants.
2. The
high-performance regional treatment plant shall be manned by an appropriate
number of trained and qualified operating maintenance and laboratory personnel
and manned continuously 24 hours a day, seven days a week throughout the
year.
3. The owner shall include,
as part of his preliminary and final plans and specifications submitted to the
department for approval, a detailed statement indicating how each of the
technical and administrative requirements in this policy has been met. Any
proposed deviation from any of these requirements shall be clearly identified
and technically justified, and shall require formal department approval. These
submittals shall also include:
a. Simplified
fluid system diagrams that clearly identify the following:
(1) The average and peak capacity of each
unit;
(2) The number of units of
each type needed to handle the normal average flow and the peak of flow;
and
(3) The number of spare units
and their capacity for both average and peak flow cases shall also be
identified.
In addition, a brief narrative summary description shall be
submitted to identify what has been done to ensure that each unit and major
subsystem can be maintained and expanded without release of effluent that does
not meet the minimum standards.
b. A simple one-line power distribution
system diagram showing how outside power is brought into the plant and how
power is distributed within the plant proper shall be submitted. This diagram
shall also show as a minimum:
(1) Ratings and
characteristics of electrical components, such as transformers, circuit
breakers, and motor controllers making up the system;
(2) Protective devices such as thermal
overloads, under frequency, or under voltage relays;
(3) Voltages supplied by all fuses;
(4) Normal circuit breaker and switch
conditions (notes shall also be provided as required to cover abnormal,
casualty, and emergency operating modes); and
(5) How electrical loads are combined into
switch gear and load center. (The use of cubicle outlines in phantom or dotted
line is suggested.)
4. The final submittal of plans and
specifications for the plant to the department shall include a systematic
failure mode and effects analysis on the mechanical and electrical portions of
the plant so as to demonstrate that a single failure of a mechanical or
electrical component will not interrupt the plant operations which are
necessary to meet the effluent requirements of Table I of this
policy.
5. Pumping stations on the
collection systems that are located in the Occoquan watershed and are tributary
to a regional treatment works shall:
a. Have
stand-by pumping units;
b. Have at
least one "on-site" backup power supply;
c. Have at least one "off-site" power
supply;
d. Be designed so that no
single failure of a mechanical or electrical component could degrade pumping
capability;
e. Have pumps and
valves arranged so that these units can be removed and replaced without the
by-passing of sewage;
f. Have flow
measure devices with provisions for recording flow; and
g. Have retention basins of a minimum one-day
capacity.
If these pumping stations are remote and unmanned, an alarm
system shall be provided at manned stations to indicate that problems are
developing and to direct maintenance assistance to the affected pumping
station. The owner of each pumping station shall be required to obtain a
department certificate.
A waiver may be sought from requirement g above, particularly
in new collection systems exhibiting no I/I problems. However, the jurisdiction
requesting such a waiver must submit documentation to the department for review
that the sewer system tributary to the pump station meets the criteria
established by the most recent edition of the Sewage Collection and Treatment
Regulations (9VAC25-790-10 et
seq.) for infiltration/inflow, and any other such information that the
department may require.
6. The major junctions in the collection
system (e.g., at least at the one to two MGD collection points) shall have
continuous recording flow measuring devices to help in the early identification
of problem portions of a collection system in the event of unexplainable high
flows (e.g., excessive infiltration). Also, such flow measuring devices and
isolation valves shall be provided between jurisdictions as well as any others
contracting for the services of the regional plant. The flow measuring devices
and isolation valves between jurisdictions shall be under the control and
responsibility of the owner to whom a plant certificate is issued.
7. Each sewage treatment plant shall have a
pretreatment program approved by the department.
8. Waste being processed in any existing
small plants shall have the first priority on treatment capacity and such
capacity shall be specifically reserved for them in the new high-performance
regional plants. New developments are to have second priority.
9. If any of the various administrative
procedures of the owner of the regional treatment plant or of jurisdictions
served by the plant prove ineffective under actual operating conditions, the
department shall have the right to place new requirements on the owner and
jurisdictions and to require any necessary action by these parties to
physically correct the damage done to the reservoir due to ineffective
implementation of the administrative requirements covered here.
10. The owner's interceptor and collection
systems of the jurisdictions in the Occoquan watershed shall be designed,
installed, inspected, and tested by the respective owner to limit infiltration
to 100 gal/inch-dia/mile/day as a maximum. The test results shall be certified
and submitted to the department.
11. Whenever the owner enters into an
agreement with a jurisdiction for services of a regional plant, the owner shall
be responsible for seeing that such jurisdictions have ordinances and rules to
meet all the applicable requirements covered by this policy. These ordinances
and rules shall meet the owner's approval and the owner shall monitor and
spot-check to see that the jurisdictions are effectively implementing their
ordinances and rules to meet the requirements covered here. The department, at
its discretion, can request the owner to submit to the department for its
approval the ordinances and rules that will be used to meet the department's
requirements covered here.
Further, any time a user violates any of the administrative
or technical requirements of the contract between the user and the owner which
can affect the plant operations, hydraulic loading, or effluent quality or
which affect the reservoir's water quality due to urban runoff (e.g.,
siltation), the owner shall not allow the user to discharge additional
wastewater to the owner's plant until the problem has been resolved to the
owner's satisfaction.
12.
Up-to-date "as-built" drawings and manuals shall be available at least once a
year for department inspection and review. These documents shall include as a
minimum:
a. Up-to-date as-built electrical and
fluid system diagrams;
b. Detailed
as-built and installed drawings; and
c. Normal operating and casualty procedures
manual. The documents shall be updated at least once a year to reflect all
changes and modifications to the plant.
13. The design engineer shall have the
responsibility of meeting the proposed effluent quality as shown in Table I. To
demonstrate that the plant as designed by the engineer can meet the effluent
standards, the plant is to be operated under the supervision of the design
engineer for a minimum of one year of continuous operation after the
"debugging" period.
G.
Other point source discharges.
1. Point
sources other than regional plants will be permitted as regulated or required
by the Virginia Pollutant Discharge Elimination System (VPDES) permit
regulation (9VAC25-31-10 et
seq.).
2. VPDES permits may be
issued:
a. For single family homes with
failing septic tanks, stormwater, pollution remediation projects, and minor
industries. The permitting of major discharges (as defined in 40 CFR Part 122)
other than regional sewage treatment plants is strictly prohibited with the
exception of pollution remediation projects that are shown to be feasible and
no other alternatives are available.
b. To an existing sewage treatment plant
constructed and placed into service prior to January 1, 2001, serving no fewer
than 10 homes but no more than 25 homes if such sewage treatment plant has a
documented history of substantial noncompliance and it is not feasible to
connect to a publicly owned sewage treatment plant.
3. No permit as authorized in subdivisions 1
and 2 a of this subsection shall be issued or reissued unless the applicant
demonstrates that it is not feasible to connect to a regional plant and that
there is not a feasible alternative except to discharge.
Statutory Authority: § 62.1-44.15 of the Code of
Virginia.
