TITLE 35: ENVIRONMENTAL PROTECTION
SUBTITLE C: WATER POLLUTION
CHAPTER II: ENVIRONMENTAL PROTECTION AGENCY
PART 373
THIRD STAGE TREATMENT LAGOON EXEMPTIONS
SUBPART A: INTRODUCTION
Section
373.101 Purpose
373.102 Definition of a Third Stage Treatment Lagoon Facility
373.103 Eligibility
SUBPART B: FACILITY INFORMATION
Section
373.201 Application Requirement
373.202 Facility Description
373.203 Population Equivalent Requirements
373.204 Sufficient Isolation Requirements
373.205 Useful Life
SUBPART C: STREAM INFORMATION
Section
373.301 Critical Length
373.302 Stream Description
373.303 Smaller Facilities
373.304 Stream Assimilative Capacity
373.305 Model Limitations
APPENDIX A Maximum Critical Length
APPENDIX B Modified Streeter-Phelps Equation
APPENDIX C Hydraulic Parameters
APPENDIX D Model Limitations
AUTHORITY: Implementing and authorized by Section 39(a) of the
Environmental Protection Act (Ill. Rev. Stat. 1989, ch. 111 1/2, par.
1039(a)).
SOURCE: Emergency rule adopted December 2, 1974, amended rule filed March
1, 1976, effective March 11, 1976; rules repealed, new rules adopted at 8
Ill. Reg. 3286, effective March 7, 1984; amended at 12 Ill. Reg. 3472,
effective January 22, 1988; amended at 14 Ill. Reg. 18289, effective
October 30, 1990.
SUBPART A: INTRODUCTION
<BSection 373.101 Purpose>>
This Part describes information required in an application for lagoon
exemption effluent limitations allowed by 35 Ill. Adm. Code 304.120(a) and
(c). An approved lagoon exemption is required before the appropriate
limitations can be specified in a National Pollution Discharge Elimination
System (NPDES) permit.
<BSection 373.102 Definition of a Third Stage Treatment Lagoon Facility>>
A third-stage treatment lagoon is defined as a waste treatment facility
employing an aerated or nonaerated waste stabilization lagoon alone or in
conjunction with one or more additional treatment units in which the units
are incapable of producing an effluent quality equal to or better than
otherwise applicable effluent limitations of 35 Ill. Adm. Code 304.120 and
water quality standards of 35 Ill. Adm. Code 302.
(Source Amended at 12 Ill. Reg. 3472, effective January 22, 1988)
<BSection 373.103 Eligibility>>
In accordance with the requirements of 35 Ill. Adm. Code 304.120(a) and
(c), third stage treatment lagoon facilities must, in order to be eligible
for consideration for a lagoon exemption, be properly constructed pursuant
to 35 Ill. Adm. Code 370, and properly maintained and operated; cannot
alone or in combination with other sources cause a violation of the
applicable dissolved oxygen water quality standard of 35 Ill. Adm. Code
302.206; and must qualify under one of the following categories:
a) Any wastewater treatment works with an untreated waste load of
less than 2,500 Population Equivalents (P.E.), which is
sufficiently isolated so that combining with other sources to
aggregate 2,500 P.E. or more is not practicable.
b) Any wastewater treatment works in existence and employing third
stage treatment lagoons on January 1, 1986, whose untreated waste
load is 5,000 P.E., or less and sufficiently isolated that
combining to aggregate 5,000 P.E. or more is not practicable.
c) Any wastewater treatment works with an untreated waste load of
5,000 P.E., or less, which has reached the end of its useful life
(see Section 373.205) by January 1, 1987, and is sufficiently
isolated that combining to aggregate 5,000 P.E. or more is not
practicable.
d) Any wastewater treatment works with an untreated wasteload of
5,000 P.E. or less which has not reached the end of its useful
life and which has received an adjusted standard determination
from the Board that it qualifies for a lagoon exemption. Such a
Board determination will only be made in an adjusted standard
proceeding, held in accordance with Section 28.1 of the
Environmental Protection Act (Ill. Rev. Stat. 1989, ch. 111 1/2,
par. 1028.1) and applicable by procedures set forth by 35 Ill.
Adm. Code 106.
1) In an adjusted standard proceeding the Board may determine
that the petitioning wastewater treatment source qualifies
for a lagoon exemption if the wastewater treatment works
proves that it is so situated that a land treatment system is
not a suitable treatment alternative. Factors relevant to a
suitability finding may include the following: cost;
influent character; geographic characteristics; climate; soil
conditions; hydrologic conditions; and the availability of
irrigable land.
2) For the purpose of this subsection (d), a land treatment
system is a wastewater treatment system which does not
directly discharge treated effluent to water of the State but
instead uses the treated effluent to irrigate terrestrial
vegetation.
(Source: Amended at 14 Ill. Reg. 18289, effective October 30, 1990)
SUBPART B: FACILITY INFORMATION
<BSection 373.201 Application Requirement>>
In order to have the effluent limits stated in 35 Ill. Adm. Code 304.120(a)
and (c) included in an NPDES permit, the discharger shall submit a written
application to the Agency containing the information required by this Part.
The application shall be on a form provided by the Agency.
<BSection 373.202 Facility Description>>
The application shall describe the facility including, at a minimum:
a) location,
b) design and operating data,
c) untreated waste load and effluent quality,
d) construction permit and NPDES permit information, and
e) useful life of the facility being replaced, if applying per
Section 373.103(c), and
f) any proposed expansion or upgrading program.
(Source: Amended at 12 Ill. Reg. 3472, effective January 22, 1988)
<BSection 373.203 Population Equivalent Requirements>>
a) If applying per Section 373.103(a), the applicant shall show that
the facility is presently receiving an untreated organic waste
load of less than 2,500 P.E.
b) If applying per Section 373.103(b) or (c), the applicant shall
show that the facility is presently receiving an untreated organic
waste load of 5000 P.E. or less.
c) If the facility is treating a waste load of less than the
applicable P.E. limit as specified in Section 373.103 but is
designed to treat a greater load, this regulation may be applied
until the facility begins to treat the allowed maximum waste load.
A specific deadline which estimates when this loading limit will
be reached shall be included in the permit.
(Source: Amended at 12 Ill. Reg. 3472, effective January 22, 1988)
<BSection 373.204 Sufficient Isolation Requirements>>
The applicant shall show that the facility is sufficiently isolated so that
combining with other sources to aggregate 2,500 P.E. or more if applying
per Section 373.103(a), or more than 5,000 P.E. if applying per Section
373.103(b) or (c), is not practical.
a) If the facility is not located in a designated facilities planning
area the facility will be considered isolated.
b) If the facility is located in a designated facilities planning
area which has less than the allowable total wastewater load, it
will be considered isolated. If load forecasts suggest that the
P.E. limit will be met within the design life of the facility, the
lagoon exemption will be granted for only a fixed period of time.
At each permit renewal, the condition shall be reevaluated based
on actual load increases.
c) If the facility is located in a designated facilities planning
area with more than the allowable total wastewater load, the
exemption shall be denied unless one or more of the following
conditions are met:
1) The facility is a permanent feature of an approved facilities
plan for the area.
2) The facility is an interim feature of an approved facilities
plan, in which case the exemption shall be granted with
termination conditions as provided for in the plan.
3) The facility was not addressed in an approved facilities
plan, and all units of government which might be considered
capable of providing service have indicated in writing their
inability to do so on equitable terms.
4) There is no completed and approved facilities plan for the
area and the discharge is not located within the area of
zoning control of any municipality or within any sewer
district or any other unit of government capable of providing
sewer service. In this case, the isolation criteria shall be
satisfied on an interim basis pending completion and approval
of the facilities plan for the area. In such instances, a
lagoon exemption may be issued for a specified time period,
subject to review and extension or termination after approval
of the completed facility plan.
(Source: Amended at 12 Ill. Reg. 3472, effective January 22, 1988)
<BSection 373.205 Useful Life>>
Applicants wishing to qualify for an exemption under Section 373.103(c)
must complete a Useful Life evaluation. This evaluation must demonstrate
that the existing facility has exceeded its useful life. Useful life is
considered to be the time span over which a wastewater treatment facility
can be expected to be economically operated and maintained. Useful life is
distinctly different from design life. Publicly owned treatment works
constructed with the assistance of a federal or state construction grant
must, at the minimum, be operated and maintained for the design life of the
project (typically 20 years). The Useful Life requirement is intended to
prevent the premature retirement of facilities capable of meeting the more
stringent effluent limits of 10mg/1 BOD and 12 mg/1 total suspended solids.
The evaluation is also intended to assess the Useful Life of individual
components of the existing facility, so that any salvageable components are
incorporated into the proposed facility for which an exemption is requested
should it prove to be cost-prohibitive to continue to meet the more
stringent limits. This ensures that the highest degree of treatment
possible is provided, in the most cost-effective manner. Applicants will
provide the following information:
a) Determine the structural integrity of the individual units in the
existing facility.
b) Review the operations and maintenance record for past performance.
c) Relate Subsections (a) and (b) to the expected life cycle for the
individual units. USEPA provides the following general guidelines
for life cycle: conveyance structures (piping) -- 50 years;
process equipment -- 15 to 20 years; buildings and concrete
tanks -- 30 to 50 years; auxiliary equipment -- 10 to 15 years.
d) Determine the present worth cost to continue use of the existing
facility over a 5, 10 and 20 year planning period using standard
engineering economic analysis. Sunk costs are not included in
this analysis. Relate this cost to user charges.
e) Describe alternatives to using the existing facility, ranging from
addition of one or more lagoon cells in conjunction with upgrading
of existing facilities to the construction of an entirely new
lagoon system. Determine the present worth costs of these
alternatives over the same planning horizons. Relate these costs
to user charges.
(Source: Added at 12 Ill. Reg. 3472, effective January 22, 1988)
SUBPART C: STREAM INFORMATION
<BSection 373.301 Critical Length>>
The applicant shall provide information about the stream to which the
facility discharges. This information shall describe the stream for its
critical length as determined by the procedure outlined in Appendix A.
<BSection 373.302 Stream Description>>
The applicant shall provide the following information at a minimum:
a) The name of the receiving stream and the progression of higher
order streams it flows into, up to and including the major river
basin;
b) The location of the point of discharge by county and United States
Geological Society (USGS) coordinates;
c) A copy of the most recent 7.5 or 15 minute USGS topographic map,
showing the entire critical stream length, the point of discharge
for which the exemption is being requested and the discharge point
of other dischargers if known;
d) A description of the stream's physical characteristics including
substrate, channel obstructions, bank condition, and degree of
meandering. This description shall also include a statement of
the presence or absence of sludge or organic deposits of unnatural
origin in amounts that are likely to elevate sediment oxygen
demand above background levels for similar streams in the
vicinity; and
e) The name, location, design average flow rate and NPDES permit
limitations of other wastewater sources (if any) which may
influence the critical length of the receiving stream.
<BSection 373.303 Smaller Facilities>>
a) Facilities which meet the following conditions need not perform
the analysis required by Section 373.304:
1) The facility must be designed for a waste load less than 750
P.E., and
2) The critical length of stream below the discharge is not
subject to significant sediment oxygen demand from bottom
deposits as described in Section 373.302(d).
b) After review of the application for smaller facilities the Agency
shall require further stream study if warranted by local
conditions including:
1) the impact of other dischargers on the stream,
2) the stream use designation or stream segment classification,
or
3) other characteristics that would limit the assimilative
capacity of the stream.
<BSection 373.304 Stream Assimilative Capacity>>
a) Unless conditions as described in Appendix D indicate otherwise,
the applicant shall use the Modified Streeter-Phelps Equation
contained in Appendix B to predict the influence of the treated
wastewater discharge on the dissolved oxygen profile of the
receiving stream.
b) The critical conditions for estimating the stream assimilative
capacity shall include:
1) the 7-day 10-year low flow value,
2) ambient BOD concentration,
3) ambient total ammonia nitrogen concentration,
4) ambient dissolved oxygen concentration,
5) the lagoon system discharge at its design average flow rate
and design effluent quality,
6) expected maximum stream temperature, and
7) other hydraulic parameters as described in Appendix C.
<BSection 373.305 Model Limitations>>
If the limiting factors described in Appendix D are present in the stream,
the exemption shall be denied.
<BSection 373.APPENDIX A Maximum Critical Length>>
The maximum critical length of a receiving stream is the distance
(downstream from the wastewater source) required at 7-day 10-year low flow
to reestablish an instream BOD5 of 5 mg/l. The amount of time required to
reestablish the 5 mg/l BOD 5 is termed the critical time of travel. The
maximum critical length can be estimated by computing the maximum critical
time of travel, which can be approximated using the following equation:
tc <Plesser than>> -1/Kc ln (5)/Ef
ln = natural logarithm function
Ef = BOD5 initially present in the stream
Kc = carbonaceous decay constant
tc = maximum critical time of travel
This relationship assumes that BOD5 decays according to ordinary first
order reaction kinetics.
<BSection 373.APPENDIX B Modified Streeter-Phelps Equation>>
The Modified Streeter-Phelps Equation mathematically defines the
relationship between carbonaceous oxygen demand, nitrogenous oxygen demand,
natural stream reaeration and the dissolved oxygen deficit as a function of
time:
D = KcLac/K2-Kc (e -Kct -e -k2t)
+ KnLan/K2-Kn (e -Kn(t-tO) -e -K2 (t-tO))
+Dae -K2t
Definition and discussion of terms:
a) D = Dissolved oxygen deficit; units = mg/l; defined as the
difference between the dissolved oxygen concentration at
saturation and the actual instantaneous dissolved oxygen
concentration at time t, i.e.,
D = D.O.(sat) - D.O.(actual). From this relation, the stream
dissolved oxygen concentration can be computed for various
times-of-travel (t's) downstream and plotted on a graph of t vs.
D.O.(actual).
b) Kc = carbonaceous decay constant; units = 1/day; this constant
describes the rate at which carbonaceous BOD is utilized in a
stream. Its value may be determined experimentally for a specific
effluent and a specific stream. The actual value of Kc depends
essentially upon the origin and strength of the wastewater, the
type of treatment that wastewater has undergone, as well as
various stream characteristics.
The following guidelines may be used for selection of a Kc value
for various applications:
1) Effluents containing up to and including 10 mg/l BOD5: 0.10
2) Effluents containing between 10 and 30 mg/l BOD5: 0.30
3) Virtually all effluents may be tested using an appropriate
experimental procedure for a more precise determination of
Kc.
c) Lac = ultimate carbonaceous demand; units = mg/l; this term may be
calculated once the BOD5 and Kc are known by use of the following
equation:
Ef
Lac = <P >>
1 - e -5Kc
In this equation, Ef is the treatment works effluent BOD5.
d) K2 = stream reaeration constant; units = 1/day; this constant
describes the rate at which atmospheric oxygen diffuses into the
water of a flowing stream. Its value depends upon the hydraulic
and geometric properties of the stream in question. Many
investigators have developed equations to predict K2. The
equation given below has been shown to yield results which best
fit the field observations of many researchers over a wide variety
of stream types:
K2 = (110.5H = 0.5832V2)<P(SV)0.375>>
H2
In this equation, "H" is average depth of flow in feet, "V" is
stream average velocity in feet per second, and "S" is the
dimensionless parameter, stream slope, ft./ft. Velocity and
average depth of flow may not be estimated but must be field
measured at the 7-day 10-year low flow stream condition or
computed from field measurements of stream geometry (cross
sections and slopes using ordinary principles of open-channel
hydraulics). Significant changes in stream geometry will change
average velocity and average depth of flow. K2 must be computed
for each stream segment as defined in Appendix C.
e) e = the Naperian logarithm base, dimensionless; e = 2.71828...
f) t = time; units = days.
g) Kn = nitrogenous decay constant; units = 1/day; this constant
describes the rate at which nitrogenous BOD is utilized in a
stream. Its value may be determined experimentally for a specific
effluent and a specific stream. Previous experimental work has
established a range of typical values for Kn of 0.25 to 0.37 per
day with an average of 0.29 per day. It should be noted that the
higher values of Kn yield generally more conservative results when
applied to the Streeter-Phelps Equation.
h) Lan = ultimate nitrogenous demand; units = mg/l; this term may be
calculated, once the initial ammonia nitrogen concentration is
established, by use of the following formula:
Lan = 4.57 (Amm-N concentration in mg/l).
i) tO = nitrogenous lag time; units = days; when a waste contains
both carbonaceous and nitrogenous oxygen demand, there is usually
a time lag before the onset of nitrogenous oxygen demand. The
time lag may typically vary from 0-10 days with its actual value
dependent upon the complex chemical characteristics of the waste
as well as various stream characteristics. The value of tO may be
experimentally determined where effluent or stream field
measurements are practicable. In the case of well nitrified
effluents, the value of t0 may generally be considered to be less
than 1 day. Note that for t less than t0 the nitrogenous term,
<PKnLan>> (e-Kn(t-t0) -e-K2 (t-t0))
K2-Kn
does not enter into the calculation of D.
j) Da - initial dissolved oxygen deficit; units = mg/l. Determined
by subtracting assumed effluent dissolved oxygen concentration of
6.0 mg/l from dissolved oxygen saturation value at the expected
maximum stream temperature.
Temperature Adjustments
KC,K2,Kn and Lac are temperature dependent quantities. The values
calculated in accordance with the above are 20 degree Celsius values.
Since the saturation D.O. decreases with increasing temperature, it will be
necessary to adjust the parameters KC,K2,Kn and Lac to reflect the expected
maximum stream temperature condition. In the equations listed below, T is
the expected maximum stream temperature in degrees Celsius.
a) Kc(T) = Kc x 1.047(T-20)
b) K2(T) = K2 x 1.024(T-20)
c) Kn(T) = Kn x 1.047(T-20)
d) Lac(T) = Lac (0.02T + 0.6)
Since the time of the year at which the 7-day 10-year low flow
occurs typically varies from stream to stream, it is not possible
to prescribe a uniform maximum temperature adjustment throughout
the state. The maximum temperature should be ascertained from
field measurements in the stream at the time of year at which
7-day 10-year low flow is expected to occur. IEPA ambient water
quality monitoring network data are available for making such
determination. This data may be obtained by contacting the
Division of Water Pollution Control.
(Source: Amended at 8 Ill. Reg. 3286, effective March 7, 1984)
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<BSection 373.APPENDIX C Hydraulic Parameters>>
In order to utilize the modified Streeter-Phelps dissolved oxygen model
specified in Section 373.304, it is necessary to determine specific
hydraulic parameters including mean stream depth, mean stream velocity and
time of travel. These factors can be estimated for the critical 7-day
10-year low flow condition through basic open-channel hydraulic
calculations (Manning Equation) for each stream segment.
The critical stream length must be divided into one or more segments of
uniform hydraulic, geometric and water quality characteristics. The
characteristics of importance in this analysis include volumetric flow
rate, average stream velocity, depth and width of flow, stream slope,
channel geometry, and BOD and total ammonia nitrogen concentrations. As a
rule of thumb, therefore, a new segment should begin where:
a) there is a wastewater discharge to the stream,
b) the stream channel undergoes a change in slope or cross sectional
geometry, or
c) stream flow increases through addition of another point source
discharge, or confluence with another stream with non-zero 7-day
10-year low flow.
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<BSection 373.APPENDIX D Model Limitations>>
The Modified Streeter-Phelps Equation used in this Part should not be
construed as a precise predictive model but rather as a means of
demonstrating adequate receiving stream assimilative capacity under
estimated worst-case conditions. Even for a general application of this
type, there are inherent limitations to the model that will preclude its
utilization in some instances.
The modified Streeter-Phelps Equation constitutes a steady state, one
dimensional model and as such is limited in its application to free flowing
stream systems that can be reasonably well represented as steady state, one
dimensional systems. Once mixing of the wastewater discharge and natural
stream flow is accomplished, there should be minimal vertical or lateral
variation (throughout a given stream cross section) of key factors such as
waste concentration, temperature, and carbonaceous and nitrogenous bacteria
population density. In most free flowing streams in Illinois (even with
predominantly pool/riffle morphology) this should not be a limitation.
However, lakes, ponds, stream segments impounded by man-made structures or
natural impediments, streams with unstable channel characteristics, swamps
and marshes are all examples of systems that may not be successfully
modeled with the Modified Streeter-Phelps Equation. Likewise, systems with
wide variations in temperature, flowrate or organic loading may not reach a
steady state condition conducive to model application. The applicant
should be aware of these limitations when applying the model to a
particular situation.
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