440486015
Guidance
Manual for Performing
Waste Load Allocations
Simplified Analytical Method
for Determining NPDES
Effluent Limitations
for POTWs Discharging
into Low-Flow Streams
Recycled/Recyclable • Printed with Vegetable Oil Based Inks on 100% Recycled Paper (50% Postconsutner) • Pleas* recycle as newsprirt
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Revision Sto. 0
PREFACE
This document describes a simplified method for conducting waste
load allocations (WLA) for relatively snail municipal sewage treatment
facilities discharging into low-flow streams, circumstances in which
«
resources for analysis and data acquisition are relatively limited.
The methodology/ issued jointly by the Office of Water Regulations and
Standards and the Office of Municipal Pollution Control-* is subject to
modifications as recommendations and/or more conolete data become
available. Thus, the method is recommended as an initial framework,
subject to revision and site-specific considerations, for conducting
simplified WlA's.
V..
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Siaplifiad laalytical Michod
for
P«t«raiaiat 1TDE3 Efflaaat Liaitatioaa
for POTtf* Oitcaarciag late Lov-riov Straava
conmci
Maaitariac iraaeh
Moaieoriag «ad Oat« Support Oivicioa
Officn of Vaear lafvTatieaa aad Staadaca*
S«pta^«r 26. 1980
Z* OmOOUCTZOH
A iiaplifi«d oAlycieal a«ch
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vi;
water quality manager to make confident and defenaible water pollution
control deciaion*. Xa many caaee* wnere similar aad relatively simple
coaditioaa exist* simplified modeling effort* that lave !*•• exteaaive
maapower aad data requirement* (than normal* more comprehensive
effort*) are oftea adequate to make such decision*. Use of simplified
efforts* whoa appropriate* caa result ia both substaatial saviags ia
State aad ETA resources aad coat-effective aad technically souad
effluent limitationa that will protect desigaated water uses aad allow
water quality staadards to be achieved.
Thia' simplified analytical method ha* been developed becauae of
the large number of relatively small municipal sewage treatment
facilities discharging into low-flow stream** sad the aeed for more
cost-effective yet technically sound water quality analyses for these
case*. Tor example* this simplified method may >e applicable to over
SO percent of the existing construction grant projection* ia legion 7.
Additionally* thi* method will help ensure that similar dischargers in
similar situation* will receive consistent consideration.
It should be noted that the aaalytical techniques described below
ere intended to represent minimum levels of aaalysis acceptable to EPA
as justification for treaaent beyond secondary. Vater-quality
• e>
aaalysts may* of course* employ more rigorous techniques incorporating
detailed iateasive surveys aad more complex models. EPA. however*
will mot accept further simplification of the methods described below*
A-4
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oalaaa such aiaplifyiag aaawptioaa art adaquataly nupportad by *
tachaical jaatificatioa. -
Tha siaplifiad ••chad diacaaaad balov ia baaad en Cht approach
propo««d by Kcgioa T. ad e« cantata and •ugsaseieoa
rac«iT«d is r«apona« to ch« Ia«iea ? prepoaal* Though scaarallj a«p*
portiT* of the overall approach* coaaaaea raraalad foata coacara
rafardiaf COM daeaila oo calcvlaciac raca coaataata* 00 tarsaea* and
pcnait coadieioaa. Coaaaqoaaclyt a«raz'al •edificaeioaa hara b««a mada
to tha ia(ioa T propoaal.
Tha ai«plifiad aathed daacribad balov ia baaad oa tha information
aad data arailabla to dai:a» Iha data baaaa for aaay of tha
ranoaaaudatlona ara quita llaltad, aad ahould b« axpaadad. Da«ra of this
•athod (aa vail aa othara) ara strongly aacouragad to davalop additional
data aad gehar information oa raaction rataa aad othar factors applicable
to tola Mthod, and to submit thia additional data aad othar informatioa,
along with suggaatad ijaprovaaaata for tha mat nod, to:
Chiaf , Waataload Allocation* Sac t ion
Haaitoriag Branch
mso/ams ara-333)
U.S. Eavirenmantal Protaction Agancy
401 M Scr««e, S.V.
Uaahiagtoa, O.C. 10460
(Telephcne: (202) 382-7056)
A-5
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C49SA.S (X)
This additional data and other Information is needed so that appropriate
additional improvements to the method can be made periodically. . Users may
also, when appropriate, make any modifications to this method that will
allow the method to more accurately represent regional or local conditions.
Any changes should be supported with an adequate technical justification,
including sufficient applicable data.
areas in the method that reqa're additional research sad/or
data iacludet
e K-rstes (reaeratioa. CBOD* RBOQ). iacludiag relating them to
waterbody characteristics* levels of treatmeat* etc.
• QOO /BOD« ratio
e diurnal fluctuation factors
e methods for performing the seasitivity saalysis
e sediment oxygen demaad rates* iacludiag relating them to
stresm bottom characteristics* levels of treatment, etc.
Where the results of tha water quality '^aiysis indicates the need
for treatment beyond secondary, State users of this method are encouraged
to coordinate the modeling analysis with a review of the environmental
benefits sad costs of the receiving water's applicable water quality stan-
dards. Such awaassmeats should be conducted la accordance with the revised
water quality standards regulations and EPA guidance, when published.
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f I» I
ii. APPIICATXOW AHD
Tbis method may be applied only if jJJ, of the following
conditions are met:
1) The discharger must be • publicly-owned treatment works
(POTV) receiving predominantly sanitary vaatawaters. Any
nonsanitary wastewaters in the treatment plant's influent
mast exhibit essentially th* asm* characteristics (s.g.*
reactions) as sanitary wastes.
2) Th* discharge must bo to a free-flowing stream in which th*
design low flow (usually th* 7-day. 10-year low flow) ia
approximately equal to or less than the design discharge flow
from the POTV.
3) Tho d«aica aiaeaarf* flow from tn« trcatMae plant «uat bo 10
WSO (13.3 efa) or !*••.
4) Th«r« ia no iignifleant iataraction b«cw««n tb« diaebarctr
boint analyxad and any otbor npatrtaa or downatra^
diaebarfor.
ftacoat «xp«ri«nca and analyaaa indicate that this aiaplif iad mthod,
when followed properly and with llttl* or no site-specific data being esplaye
"ahould oomally result In both technically sound water quality justifications
being developed for nitrification levels of treatment and substantial savings
la State and EPA resource*. However, it has also been acted that this
aiaplifled analysis alone (i.e., without any site-specific daea) usually
cannot provide the confidence needed to adequately justify permit limits
•ere stringent than about 10 «g/l CBOD^ and 1.3 mg/1 HRj-jt, including rela-
tively coatly .filtration treatment after nitrification. Therefore, this
simplified method cannot be used by itself to justify permit limits more
stringent than 10 mg/1 CBOOj and 1.3 mg/1 HH3-H (including filtration after
nitrification).
A-7
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C499A.3 (I)
Where treatment acre stringent Chan 10 mg/1 CB005 *nd 1.5 agM NH^-S
(including filtration after nitrification) appears to be needed. Appropriate
supporting site-specific data should be collected and used in the analysis
In order Co increase confidence in chc variables usad in ehis matbod, in
the modeling results that ara obtained, and, nose importantly, In tha treat-
ment decision itsall. This addleional level of analysis should also be
aceoatoaniad by s rigorous sensitivity analysis (see Section III-C of the
•ethod). Based on past analyses sad coastruction grant project reviews, it
appears that this situation (e.g., the need for traataent beyond nitrification)
will seldom be required except in certain cases where snail streaas with
very low assiailative capacities are encountered.
Ueter quality la this type of system is highly dependent on
effluent quality. Hence, upstream quality is less significant here
Jsaa in systems where the upstream design flow is much greater than
design affluent flows. This method can also be applied to simple
systems where the upstream flow is greater than the FOTV's discharge
flow, provided the upstream water quality and reaction kinetics are
well documented.
XXI. FtOCZOOSZ
Xa order to determine the level of treatment required for a POTW,
the following analytical seepa are recofeaeadedi
(a) gather necessary data
(b) perform an ammonia toxicity analysis
(c) perform a dissolved oxygen analysis
(d) perform a sensitivity saalysis
A-8
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»)3A.S (X)
(*) interpret the results, and determine the final effluent
limitations.
These five steps of the Simplified Method are discussed below.
A. Data feouirements
The data required for the Simplified Method, and some of their
possible source* are listed below*
1) stream design flow-sources include OSGS low-flow publi-
cations) drainage area yields} measurements.during low-flow
period*.
2) "T**^*** »•*•* q««tigy-taei«i^la^ the a«e««««z7 DO* 100*
a«B0mia* pi* alkallaity* teBBeratvze and other data needed
for chi* Method. Sources iaclo4e hiatorical data (e.g.* in
STOUT)} State* DA* or other water quality monitoring;
••wag* treataeat plaat monitoring; traaaferable data from
•iailar ttreama.
jmj^jj_gjmj£tjgjxtj_ci.j'^ttgit>^ *t •trees elope*
depth* etc. Sources include field measurements * VSCS topo-
graphic aape; special Corps of bfineers or county project
maps; stream gazetteers.
4) gj»« at ^•pyrnt/T»iftg-try-.«anyg«a include dye studies;
direct velocity measurements; calculations based on field
measurements of widths* depths* etc.; estimates based on
slope/Telocity relationships.
3) •wi.ii*-** <<««4yn f i (nr-aonygM include State or local agency
population projections; Step 1 applications.
the
pi. alkalinity* temperature* and other data needed for this
Method. Sources include treatment capabilities for different
level* of treatment* presented herein} other data can be ob-
tained from State* tPA. or other water quality/effluent moni-
toring} sewage treatment plant monitoring: transferable data
from similar treatment plants.
Direct field measurement* of tfcae-of-trsvel/Telocity* upstream
quality* stream physical characteristics (such a* depth* type of
bottom* benthic deposits* etc.)* and other data should be employed for
each segment studied, most notably for those where post-filtration of
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the sewage treatmeat plaat efflueat is coaaidered. Siaet thai* data
are readily obtainable by meaaa of short duratioa* low resource
surveys* effort* should be made to obtain th« data through State
agency monitoring programs or *a part of tha 201 grant process. Vhea
each data art not available* estimates can be made fro* some of the
suggested soarees listed above. Ike impact of leaa site-specific data
should be coaaidered ia the seaaitivity aalysia. Time-of-travel
studies provide the most oaeful data vaea the vpatreaa flow aad
ezistiag savage treatmeat plaat flow are equivaleat to the s«a of the
opatream ?Ql(J «ad the treataeat plaat desiga flow. If flowa ia
the i^ediate raage of the deaiga flow axe aot eaeo«atered dariag the
ti»e-of-travel studies, a secoad study at a differeat flow will permit
extrapolation of the data to the deaiga flow.
la a minimtait all modeling efforta aaat iaclude: (1) a search
for all applicable hiatprical data and information (e.g.* ia ST01TT.
old aodeliag or water quality study reports- treatmeat plaat sa^orda.
etc.) to support the current modeling work* aad (2) a general on-site
reconnaissance visit to visually observe the system to be modeled (to
gain a better intuitive understanding of the system).
A mass balance analysis will be used to determine whether the
mitrificatioa uait process ia required oa the baaia of iaatrasm
aMoaia toxicity. The total aeawaia-I limitatioa for the proposed
*
diacharge will be determined by uaiag the applicable-water quality
staadarda (VQS). upstream flow sad backgrouad coaceatratioa. aad
deaiga efflueat flow aa follows (2):
A-10
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where CB • allowable design ditchers* concentration ef total
0 ammoaia-* for POTV.
» water quality standard limit ef total ammonia-H
(usually based oo ua-ionized ammoaia-li standard aad
selected pi aad temperature)*
• upstream or background coaceatratioa of total ammoaia-H,
• design POW discharge flow rats*
• upstream design low-flow.
The allowable iastrea* total a«*oaia-l coaeaatratioa
will aenaally b« baaed oa ta« watar quality ataadard for ua-ioaixtd
aaaoaia-l cad th« azp«ctad valaaa of pi aad tav0«ratur« dowaatrtam of
taa diaeaazs* (if « applicable total aoaoaia-I ataadard is specified,
Cgga will equal that ataadard). The ralue of CgqS eaa be deter-
miaed from a table or graph which relatee the toxicity of ua-ioaized
aamoaia-I to pE and temperature (aach a table aad jraph ia preacated
ia Exhibit 1). ¥hea aelactias Sns* °°* *oould be oure to aae ap-
propriate Taloea for the expected dowaatream pi aac Semp^^enre coa-
ditioaa doriag the deai^a aeaaoa( ***** miriag of the discharge aad
the receiriaf atream. If ao aa-ioaised or total ammoaia-I ttaadarda
are available for oae. the followiax criteria are recomMaded:*
*additioaal research iadicatea that the** criteria may ia many caaea be
more atrlnjeat than aeceaaary to protect water quality. It is recommended
that the latest tPA ammonia toxicity criteria, when promulgated, be uaed
ia conjunction with the euppartiaf ammonia criteria implementation guidance
document. Until the aew OA ammonia toxicity criteria are promulgated, AT
facilities proposed solely to prevent ammonia toxicity may be approved only
with supporting Justifications based ao either: (1) site-specific biologic*:
data ahowiaf that tha designated us«« caaast be restored without reducing
amsmls soxicity, or (2) bioaasay data (eithe? from a laboratory or aiailar
flite) for indigenous species shoving that exist lag or future ammonia toxic it;
levels will impair designated usa attainment (exposure levels aad duration*
for those tests abould be similar to those occurring or anticipated to
occur ia tha receiving water). Rota: After publication of aew ammonia
toxicicy criteria >y EPA. Advanced Treatment processes proposed solely to
prevent ammonia taxicity may be approved consistent with these criteria and
this simplified aathsrf.)
A-ll
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« various pH and trnpcnturi valuw.
A-13
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093A.3 (Z)
a 0.02 mg/1 un-ionized ammonia for freabwater cold water
habitat
• O.OS mg/1 on-ionized ammonia for freahwater warm water
habitat.
Tha expected valaaa of pi and temperature dewnatraam of tha die-
charge ahoold be baaed on the pi and temperature of the POW effluent
and of tha opatraam water*. Zf •officiant 'temperature data ara avail*
able or can ba estimated for tha POW and for tha • cream (upstream of
tha discharge point)* the expected downstream temperature can ba cal-
culated aa follows:
l. 2)
whara II • raaoltant vatar tavparatora dovnatraaa of diaehars* *ft
0^ * vpatraa* datijn lev-flow*
QB » daaicn (WTW) diacharsa flow rata*
t- • oyatrea* watar tamparatura*
* •
tjj * taBparatora of POTW affluent.
Alao* if ioffxciant pH data ia arailabla or can ba aatiaatad for
tha 70TV and for opatraaa* tha Bathed ootlinad in Appendix Al can ba
oaad to dataxmise tha expected downatreav pH.
• Vhan •officiant data ia available for pi and temperature. u*« of
tha maxiaoB pi and tanperatore valoee arar recorded ia (anarally net
raaliatic. Zt ia •era appropriate te oaa pi and temperatora valaaa
which ara exceeded 23 percent of tha tiaa daring tha critical low-flow
aaaaen. It appear* that the likelihood of hawing aiaaltanaoua "worat
caaa" ocearrancea of beth pi and tamperatora aignifieantly graatar
Chan their respective 22 percent axeaadenca valuta along with daaign
low-flow conditiona ia net very great: however* additional raaearch
A-13
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CA95A.5
should b« conducted is this art*. Waoa Actual strtam or POTV daca ar«
liaited or not availablt. data from similar at*rby scrtarns aad FOTtfs.
or equilibrium water temperature data* may b« used «• design condi-
tiooa aad to help establish the raage
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C*»3A.3
(DO) analysis (Step C. below ) has been completed. The 00 analysis
may indicate the need for a redaction of ultimate oxygen demand (UOD)«
which would also support the need for the nitrification unit process
at the plant (a process known to be more economical than filtration)
for 000 removal, lowever* the latter conclusion is based on the
implicit assumption that all of the iastream amaiinls will exert an
oxygen demand in the stream segment under consideration* i.e.* that
nitrification occurs instream.
In situations where the 00 analysis does not indicate a need for
advanced treaaent levels* but the ammonia toxicity analysis predicts
toxicity problems* consideration shall be given to using pB adjust-
ments (i.e.* pB reductions) of the effluent daring critical conditions
$e control ammonia toxicity in lien of requiring nitrification. This
consideration should include a determination of whether the temporary
lowering of pB and increase in total dissolved solids (T08) concen-
tration would have any significant iastream ecological or other
effects.
Xa addition to this mass balance analysis* a qualitative if not
quantitative assessment of nonpoint source contributions of ammonia
must b« mam*. This assessment may reveal that nonpoint source pol-
'.ailam ma? >• «l *««f ficiaat magnitude to preclude attainment of water
quality objectives in terms of ammonia concentrations. Am example
which illustrates this point would be a treatment plant discharge
located in a predominatly agricultural watershed that has significant
A-17
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CA9SA.S (I)
aoapoiat source problems, Jecause aitrificatioa alone may not solve
an ammoaic toxicity problem, aoapoiat source controls must also be
considered before aitrificatioa ia chosen. Vational guidance for .non-
point source analysis related to facility planning ia presently being
and is expected in the near
A tivplif i«d Str««t«r>Fa«lp« (3) aaalyti* will b« o««d to
the «fflu«at di««olT«4 oxyj«a (00) cad BOD llaitatioM for
th« MTb. Thi« *ppro»ch iacorpor*t«« beta eacboaae«o«« (C800) and
aitrogtaoaa (HBOD) 0x71 is d««ad« ia th« ualytia. Th« •quatioa oa«d
to c*lcwl*t« the DO deficit dovn«trta froa the peiat «o«rce is taovn
belovt
« D0 ezp (-K2t) (Z^. 3)
where 9 • the 00 deficit (•
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C4MA.5 (X)
Kj m OOD reaction (decay) rate (baae •} (I/day)*
*2 • reaeratioa rate (baae •) (I/day)
Ij • nOD reaction (decay) rate (baa« •) (I/day).
t • travel time b«low discharge (day*)*
S • sediment (beathic) oxygen demand («B/«2/day).
I * atrcav depth (••ears)*
the iaacria* a^craf* M ceacaatraeiaa afi a (iT«a poise devBttrtaa
of the diacfcarge poiac ia calculated by oaiag the folleviag eqvaeiea:
vfaere 0°A7C • iaatreaa aTcrace 00 caaeeatratiea (•(/!)•
DO..- « •atoratioa 00 coaceatratioa at specified water
temperature (m»/l). thi« caa be detenaiaed fro*
Exhibit 2.
0 * aa defined above.
Calculatioaa oaiac the above equation* aad a specified set of eo-
effici»nt« aad aaaoaiptioaa apply for a givea uaifora stream reach. Zt
ia. iaportaat to subdivide the stream iato individual oaiform reaches
vherevex aay significant systea changes occur (e.g.* changes ia chan-
ael geoaietry* significaat tributary inflows* etc.) ao that appropriate
coef ficieata aad aaamptioaa that adequately repreaeat each reach caa
b« applied to the respective stream reaches whea the model calcala-
tioaa are made.
A-19
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A-21
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The universe of possible caefficieats aad assumptions that caa be
used ia the model may vary over a vide raage. aad caa result ia sig-
aificaatly different predictioaa of iastream DO. It is extremely
important that the best possible sstiaats of these parameters be
obtained for each case to ensure that they adequately represent the
stream system to be modeled. Site-specific data should be uaed
whenever possible. Vhea a campreaemsive field survey is aat feasible*
appropriate data described ia the literature ar available traasfer
data may be ased. lovever* if literature data or traasfer data are
uaed* it is strongly eacooraged that t sacral reconnaissance visit of
the site to be modeled be made ia order to qualitatively evaluate the
applicability sad reasoaableaess of tha d*ta being used. The coeffi-
cients aad assumptions to be ueed aad ainimna site-specific data
requirements for this Method are discussed further* in the next sec-
tion. It is important to exuare that the coeffitissta aad assumptions
which sre used ia the model do adequately represent the conditions in
each uniform stream reach* sad that they are changed ia the aodel* as
appropriate* betveea the stream reaches beiag modeled to reflect say
system changes between the reaches (e.g.* make appropriate change* in
coefficients* travel tiae* etc.* to reflect significant changes ia
slope* channel geometry* beathic characteristics* etc.)
After the appropriate assumptions ere made aad caefficieats
selected* tha location of minimnm DO coaceatratioa (i.e.* tha sag
poiat) is to be determined. This caa be accomplished by spplyiag
A-23
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iacremeatal time period* ia Cquatioaa 3 sad 4 aad act lag vaerc the
,{„{»• 00 coaceatratioa occurs. The aumber of trial-aad-error
iteratioaa caa be •iaimixed by first usiaf the folloviag equatioa to
dctermiae the approximate locatioa of ehc sag poiat:
i <««. 3)
te -
. * «pvrexia«e« tia« («adv a«ac«» 4i«c«ac«) to eh«
* (critic*!) poiat.
• BOD n«ctio« r«C« (for CEOO* BOO* or •v«ra(« of
evo raeoot so* eost« kolov)*
iaitUl 90 deficit («t di«caar«« poiat).
ultima t« BOO coac«atrmtioa («t discaarso
poiat)
Ihoro 900 ad BBOD hart difftrrat rat««. the sac poiat caa »• booadad
by aaaicaiaf first the lover and taan eao ai^bar ?ata to tho total
•Itiaata BOO. or approsiaatod by avcraciac th« two rataa.
The aoxe orarall atop ia taia Xothod ia to aatabliih ta« allov-
*
abla loadiac rataa aoodod ia order to meet the water quality staadarda
at the critical sag poiat. Taia caa be accomplished by applyiac* ia
aa iterative maaaer. avcceaaiTely lover* 900 sad BOD values uatil the
BO aeaadarda are met at the sac poiat. Am alternative to this "trial
amd error" method for dissolved oxysea ia to aeperately calculate the
diaaolved ozysea deficit due to each BOO source (e.g.* upstream BOO*
aedisMmt demaad, plaat carboaaceoua BOO* amd plamt aierofeaous BOO).
A-24
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By knowing the relative contribution of each BOO source eo the total
deficit when using this alternative approach, aad sine* the various
oxygen deficits are additive (see Equation 3), ic is an easy task to
identify the combination* of vastavatar 100 reductions ;!iat will
achieve water equality standards end to select the combination that
will be the Moat coat-effective.
A* stated above, it ia extremely important that the best po*aibl*
estimate of the parameter* need ia the model be obtained for each
COM, and that they adequately represent the system being modeled.
The next several subsections disco** recommended parameter valuea and
Maumption* to be uaed with the Simplified Method. The following
point* era addressedi
flow regime
target DO
treatment capabilities
rate constants
iaital deficit determination
conversion from CSOO to BOO.
poet-aeration
nonpoint sources.
The recoBBMndationa nade below are intended to help the Siatplified •
Kethod user to develop modeling results that are consistent with ehe
explicable weter quality standards.
1) now tMJaa. loth low-flow and high-flow conditions should be
eaeeaaed to determine the critical conditions. In some cases, severe
lint source pollutant contribution* during high-flow* might
4-22
-------
preclude attainment of desired vatsr quality objectives. If the high-
flaw condition is found to be critical, further analyses of aonpoiat
sources should be conducted.
The flow regime to be used ia the Simplified Method ia the desiga
low-flow specified ia the applicable water quality staadards. This
flow will, ia most cases, be the 7-day. 10~aar low-flow <7Q10)»
If no desiga flow is specified, the 7Q1Q should b« used for design
purposes. If aay flow value other than those specified above is used
ia the aaalysis. a sound ju-tifieatioa mast be provided to support the
use of this value.
2) f»r^»f 9im*a\ir»A Qsr^««. 00 scaadards are oftea presented as a
•iaiaasi «e «ii »4«««; Mae States include aa average value aloag
with the miaiaoa. Outputs (the DO siawlatioa) from steady-state
•odeIs are based em the 4veraf.iag period for iaput loadings; they*
therefore* represent the average DO conditions likely to prevail at
the flow eoaditioa being sismlated. The tvo aajor factors that caa
cause the actual suaiaaw DO to be considerably lower thaa the average
predicted by steady-state nodeI covputationa ares (1) diurnal varia-
tions ia loadings to aad frost the contributing waste treatveat plant*
sad (2) diurnal variations of iastreaa DO caused by algal photosynthe-
sis aad respiratioa. The aagaitude of these variations is likely to
differ froa plaat to plaat aad from stream to streaa. The problsa is
farther coaplicated by the fact that prevailing fluctuations ia a
A-26
-------
•cream may be radically altared under construction of a larger criac-
meat plaat with higher levels of treatmeat* aad chat quaacification of
these fluctuatioas through iateaaive field investigations may aoc ac-
curately defiao these future conditions. For this reason* us«rs of
this Hschod art urged to obtaia additional fitld data so that instresm
respoasee cam be hector carr«latad with differeat lorols of troataoatt
aad chat b«ttor osciaaeoo vador projected eoaditioas eaa •• mad*.
Vhoa modoliaf* th« followias 00 targets should ho aaodi
(a) If tho 00 scaadard la *spr«ss«4 as aa avorsf* aad a miaimosi
ro^mirmmoat (••$•• am avorago «* 3 mf/1 aad a aiaiwai of 4
af/l)» tho avorafo auabor (t.(.* 5 ac/1) should ho used as
tho tarsoc.
(h) If tho 00 scaadard is axprossod oaly aa a miaimosi (a.(*« a
miaianmi of S mf/1 at all tisMs)* tho target 00 may ho
obtaiaod by addiaf oao^half of th* dional variation to tho
00 staadard (o*c.« for a total diurnal variation of 1 mc/1*
thorn tho target is 3 msj/1 • 0.3 mc/1 • 3.3 a«/l). la tho
abaoaeo of adequate sise>coecifie or traasfarable data* 0.3
mc/1 should ho added e* tho 00 scaadard. Zf any other
values (either lesser or greater thaa 0.3) are used, they
muat bo supported by adequate data.
There i& aot a scram* quantitative basis for using tha
recoeaeudod value of 0.3 *a/l to eompensate for diurnal variations;
the choice is hased ia part oa tho acknowledgement of tho existeace of
omch variatioas aad oa tho need to allow some reasonable compensation
ia tho absence of aa adequate data base. lowwver* Thomaan (19) feels
caa« thora is a basis for us in?, tho 0.3 «c/l value, but this value ia.
aaaociatod more with raadomt rather thaa just photosythesis/respira-
tioa, fluctuatioaa. additioaal fiold studies should ho conducted to
either support or nedify this value.
A-27
-------
3) Tp««fMBf c.in«hn it (•«. for typical doaticic vasctvactri. the
folloviaf, «ff ln«ac coecaacracioaa should ordinarily bo asauaod for
•o4«liaf porooaoa. Thoao valuoa art 30-day avorafts that would b«
«x»«ctod dariaf v«im siavacr •each* (i.o.. 4ariaf eoadicioas tiaiUr to
tbou b€iaf wdcicd).
urn,
S«caa4*r7
•itrifictcioa («ia»U
•cago or cvo cca(o)
Oxidacioa Ditch
•itrificaeioa plaa
Filtratioa
100 -300
30 (or ISZ
roaovol)
3 - !*•
10 - 15
3-3**
12-35
10Z !•*• tham r«w
eoaecatracioa
1.0 - 1.3
1.0 - 1.3
1.0-1.3
**(S«« Aopoadiz 12 for elarificacioa.)
Th« valu«a soloctod from the raafit (iv«a abov« ahould dtpoad oa ch«
iaflacac eoaecatracioaa («.f.« lo««r Tal««« should b« MM for low«r
iaflucae eaaeaacracioaa).
4)
cricieal T«!MO ia DO aaa
of
aaall straava ara tho roaoratioa rata* aad to a loaaor oxtoat* tho
CBOO aa4 IMO docay ratoa aad offlaoat 00 Icvcla. Kaay fonralatioaa
•••a d«rolopo4 for prodictiac aeraaa raaoraeioa rataa baaod oa
A.-28
-------
physical* characteristics such as stream width* depth* velocity* and
slope (A.3). laceat work by Kathbun (6) aad by Graat aad Skavrooeck
(8) iadicates thac tha Taivofloa formula (7.20). ia which Kj is
calculated by Conation i* tends to most accurately predict scream
reaertioa. Presently* the data base ea which most reaeratioa
eauatiaas aad recoumeadatioas are based is quite limited. Additional
data collectioa efforts aad research are aeeded ia this area.
Tha Tsivoslou formula, preseated below, should be used for
cammutiaf reaaratioa rates oa small, shallow screams}
Kj • CTS at 20°C (Zq. 6)
where t, » reaeratioa rate (I/day)
T » stream velocity (ft/sec)
S * straw tlope (ft/mi)
C • proportionality constant with the values shown below:
C • 1.8 for 13QS10 cfs
• U for 10
-------
aeparato 00 calculationa usiag both the higher aad lower C valuea
M that lower aad upper liaies of predicted DO can be eatabliahed.
Zf thia range of predicted 00 it found to be relatively large, it
ia recommended that additional work* including field meaauremeata*
be performed to help reduce the uncertainty ia the reaeratioa rate
to be ueed.
O'Coaaor's re«eratioa fonraU. preaeated below* a«y be uaed for
Urfer, deeper acreaaa with mare vaifora chaaael (eoawery or thoae
with *i«aific«at pooliac (*)*
« « 12.» T0'5/!1'3 «e 20°C (Ee.. 7)
T • screes velocity (ft/ae«).
• • everace atreeei depth (ft).
The values of f and I used ia the above equations should be based
oa actual field measurementa to that the aacertaiaty ia the rate caa
be reduced. The value of S caa be determined from field measurements
or from appropriate maps.
Any otdev applicable reaeratioo prediction methods may be uaed ia
lieu of the above methods only if these alternative methods are
supported by sa adequate technical justification that includes
sufficient field data collected from the area.
(b) CMP B««-«Y tMtmtr )_ 4 review of reactioa rates measured oa
low flaw streams with similar characteristics showed that CMD rates
generally range from about 0.2 to around 3.0 er more (10* 11* 12*
U* 21*)* depending ia part oa depth aad degree of treatment (see
A-30
-------
Exhibit 3). The aiaiaal data available {or saall. low flew atreaaa
with treatment greater thaa aecoadary laueat that the C100 race*
aadcr theac caaditioaa typically fall between about 0.2 aad O.S (at
20°C). Adjuatias CMO racaa by depth aa propoeed by lydroaeiaaec
(13) a«(s«aca 0^ Co b« a r*fr«s«&caei«« ««ltM for eh«a« low flow
atrtaaa with a Macly atablo fairly rocky bottom, aad aboat 0.2 for
•tr«a*a with a primarily oaatablo aadiawat bottov.
Vaia« thia approach* CMO thoa bocoaas (14)t
Kj« C (l/t)"0'434 for •< I ft. (la.. »
* C for I >« ft.
wh«r« Kj • dOO docay ,r»t« (I/day)*
—.1 * av«raf« atraaa dapeh (fc)»
C » 0.3 for seraaaa wieh aotcly atabla fairly rocky
bottoaae
C * 0.2 for atraaaa with primarily maatabla aodiaaat
bottoata.
Zt •boaId b« aotod that Equaeioa 8 generally r*pr«a«ata an avcragt of
a r*aco of pocaibla valuoa at aay givoa dopth. Based oa liaiitad data
proaoatad ia tho litoratar* (11. 13* 21) aad olaowaoro (10. 12: alao
a«« exhibit 3)* tho following raagoa of tho ClOO rato ar« prtaoatly
aauoatod:
A-31
-------
§
8
1
8
]
I • I
o
1 * * I
1 i Is i
** s«
is ":
•
w
k
c
- 'I '3 3?
s si sr f?
v
-o
e a
2 2
^< ^i
M
•
e
J» •
S • M
Ml "I
\ I! fl !
1 r r i
;s
s*
«l
•• M
M ««•
«• •
l|
-------
£ 3 £ 2 S 3 2 2 3 5 S 2 £ §| w
8 M M M M M M M M M M M M M
to 0S02S°2 S SS328
v
8e
Illlfll
7777777 7 «7 77 7
• ml m • • ~ ~"
•M
1 ^
MM
*'I l"^
«s| | ||j|: «
• •'••'•Jca 2 — « f ff £ 9
1 Sii2J!8 i ZilJil §
1 ,
. i iiiiii j
3 5 «*«**«« " J8-5-JJ «
A-33
-------
C1QP
LlTTfl P* Ty»«t>aOTt M« »»<•!«•
Secondary treatment 0.3 1*5
Creator than secondary
• streams with meetly 0*3 0*9
stabla fairly rocky
bottom*.
• streams with primarily 0.2 0.4
umstabla sediment
botl
(Botat Thuaa rangee ara baaed oo a »««T ii"itai data tat; thay ara
aabjaet to aoaificatiea. aa vacaaaary* aa a4dieia«al raea data
aza «ubadttad to OA Baadqvartara. Daara ara «f^»d to
eallaet «ita-«pacifie rata data vtaasarar poaaibla.)
. baaa a. at 10°C)
Iqoatioa I may ba «aad to aatiaata taa 01OD rata vichin tha raa^a*
•facifiad aoora. Vaara of tai* approach should aota that* at bast.
tha abora aqoatioa if a erode* though rational* aapiriciam. baaed oa
a limited data sat. A much larfar data tat coaaistiac'of accurate
Kj maaaureaiaata for differ eat larals of jaaataaat aad types of
etraaaa ia aaeded before a «ora precise avpirical correlation aquatic*
•am ba developed. Towards tola aad* Stataa aad OA tecions ara
•XUd to expand relevant data basea* aad to submit these data aad
•utsaatiena to DA laadquarters to aaaiat ia tha refinement of tha
above approach amd rangaa. Poat-couatructioa imtemaive surveys to
•aaaura ^ (and X) below AST amd AVT plants would aid thia
A-37
-------
•{fort significantly. 9sers sre encouraged eo collect site-specific
data or to as* transferable data ee help reduce ehe uncertainty in the
CTOO rate eo be selected. Any deviations fro* eh* above approach »u«t
be supported by an adequate technical justification.
(c) «flt> B~.T *,t. (T^\ s«r«r«I •BvireoMatAl faeeera
b««a •bom eo iaflocac* the r«e« «c which «ie?i/icaeie« occurs.
th«B «r« pl» e«Bp«r«e«rt* •o«p«atf«4 partielo ce«c«&traeioo«
f«roMC«r«. other pollaeaaes that iahibie eho aierificaeioa proeai*
!o«c*» torn* toxic* )• oa4 eho boaeho* of eao rccoiTiag vaeort. Vhilo
oo aeeoBpe i« aado in ehi« Hoehod eo quantify eho «ffoce« of eh«*o
factor* on Kj. aoora art «xp«ct*d eo dototmino fnalieaeivoly vhothor
or not nitrification it likely eo occur in eho sobjoec *tr«aa. Zf «o.
•aori Bo«t d«t«xmin« vn«th«r or not condition* aro optima? for
slerification. For «za«pl«» •«r«ral ra* •archers hare shown that a pi
in the rant* of 1.4 to 8.6 is optimal for nitrification, with a rapid
decrease in nitrification outside the rant* of 7.0 to 9.0. Because
most State water quality standards require a pi in the rang* of
between 6.5 or 7.0 and f .0. it is unlikely that Che p£ factor greatly
influence* the occurrence of nitrification, lowerer* consistent pi
•••errationa ia the rang* of S.4 eo t.6 indicate that ehi* factor i*
•ooduaive eo •sriarm nitrif icati>». litrif ication i* also a function
•f available benthic surface area for nitrifying organism* to attach
ehem*elT«*. For example* if a stream bottom ia completely devoid of
A-3S
-------
aurfaca* (*uch aa rock** etc.) on which aitrifiar* can attach
themaelve*. it ia likely that aitrifi ition will not be a sigaificaat
factor in the 00 enalyai*. Conversely* a •hallow stream with a rocky
bottom ia likely to have a hi(h nitrification rate.
4 aite inspection will indicate the likelihood of nitrification.
and ahould bo conducted. Baaed on the obaerrationa which are made
during the inspection, the uaer muat eatimate the applicable HBOO rate
value. Zn view of the tenuoua nature of this rat* selection
procedure, particular care should bo taken ia evaluating the effects
through sensitivity analyses, another poiat to conaider ia the
outcome of the ammonia toxicity analysis. If it waa detemiaed
previously that ammonia removal ia required on the baais of ammonia
•—-~
tanicity considerations, then the role of Kj in the overall 00
analysis become* somewhat leaa critical. On the other hand* if the
ammonia taxieity analysis doea not clearly indicate the need for
ammonia removal, then the decision to provide nitrification at the
treatment plant will hinge solely on the 00 analysis. This nakes the
determination of the Ij value much more critical. The water quality
analyst muat then carefully aaaeea atream condition*, and aaaiga
reasonable rate coefficients* accordingly.
laaed on limited observation* of HOO decay rate (2{ also see
exhibit 3). it appears that, where inatreem nitrification ia found to
occur, moat tj value* range between about 0.1 and 0.4. T« •*•
4-39
-------
absence of applicable siee-specifie data. a Kj value within she
rant* of 0 ee 0.6 ii to b€ selected. This sal teflon should b« based
la pert oa a aita inspection (as stated above), and on any appropriate
available eranafar data. Generally, a K^ value of around sera
should be (elected only if atreof evidence suggests a lack of inacream
nitrification occurrinf under the projected conditions. Otherwise,
the Zj value* which ere selected might be roughly 0.2-0.3 for
deeper streams with a primarily sediaent bottom, around 0.4 for
shallower streams with a moderately rocky bottom, and about 0.6 for
shallow, rocky streeaa. The user is strongly e^ioura«;«d to collect
site-specific data, and data fro* siailar sites, whenever possible to
support the selection of the HBOO decay rate.
(d) Sedia»nt (Benthie) Oxytan Deavand (S). Sedismt oxysen ia a
factor that is often significant ia the 90 analysis. For the types of
/
situations applicable to this Method, Thomann (19) aucsasts that the
following bench ic demand rates be uaed when simulating stream DO
response to various treatment 1 eve 1st
S(gm/»2/dav of 0«t 20°O
Ticinity Downstream
Treatment Level of Outfall of OutfalT '
Poor Secondary Trt 2-4 0.3 - 1
Becoailary Trt 1*2 0.3 - 0.7
Greater than Secondary 0.2 - O.S 0.1 - 0.2*
*(Even with high levels of treatment at the point source, there will
usually be at least a minimal benthic demand preaent, e.g., due to
"background" or other sources).
A.-40
-------
For the purpose of this aaalysis* th« beathic demaada should b«
considered eo be at a mq*«"" uader future coaditioaa. ualess
•ite*«pecif ic cireumstaacea indicate * coatiaued presence of
substantial beathie deposits la cat future («.f* fzoa aoapoiat
Tho «pplie«bl« r*CM •ofstst«4 tbor« •hould b« a««d la tho
lytia* «B!MS flit* Uflpoctiou iadieato ta«t ai«h«r or lovor «•!«*•
•bmld ••
Vhoa •oloetiac tho boathie doaaad r«to f or f«earo eoaditioao*
id«r«tio« •hraU b« giVoa to tho fact that thoro mi«ht bo
eoatiaaod other •oureoc of boathie domiad* tueh •• fro* aoapoiat
oooreoo. Thoroforo* • tito ia«poctio« •hould bo eoadttctod to
dotozmiao tho characteristics of the stre«i bottom aad the areal
ezteat aad Magnitude of the beathie demaad* aad to rrreal aay possible
itiauiac beathie
(e) 2fls^&aZA£llCJK_£flzZJtC^ifiUL_fl£>jAJjCJL^&&_KAL&B,* Tsjaperatare effects
oa tho Tariooe reaetioa ratee caa be approsiatated by the follovias
equations s
where (SB)T • adjusted beathie demaad rate for specified stream
temperature*
(SI).. * selected boathie demaad rate (for stream
w temperature of 20°C).
-------
T • specified scream cewperacure (*O .
t-20
« KT * K20 •
where Kg • adjusted K-rata for specif ied screw temperature.
* selected K-r«e« (for •tr«« t«p«r«tur« of 20°C).
T « «p«eifi«4 strtw tocpcratur* (°C}»
• • 1.047 for tj.
» 1.024 for Kj.
• 1.08 for K
(3) t«4f<«T p«^
-------
which was calculated u.iat Equation 2 (ia the -AmsKaxA Taxicity
Analysis* section). This €«i be determined fro. Inhibit 2. IT using
B00 and DOUT. the iaicial mixed dissolved oxygen deficit (Bfl)
can b« calculated as follows:
°o
(6) Conversion from OOP., eo CBODs. tacio* of QODu/CSOOs di«cu«««d
h«r«ia »r« ba*«d eo « aicrifie*cion-lnhibic«d CMC. Th« ratio U a function
of eh« level of treataent and the aaaoeiated dtfradabiliey ef the waste.
Thua higher ratioa are expected and have been observed for higher levela of
ereataent since the 0800 remaining in sere highly treated effluents degrades
nore alovly than that in lees treated wast eve t era. It is recoaainded that
the permit 100 effluent lisULta which are finally selected after the water
quality analysis be written as a carbonaceous and not a total 8005; the use
of CBOO* effluent llaics and, correspondingly, a carbonaceous (inhibited)
BOD test when Monitoring the affluent can help avoid 'potential data iaac-
cuxacias chat can result from nitrification occur ing in the bottle during an.
uninhibited BOD e**e due to the presence of juff&sient aitrif iers ia the
test bottle. Data submit ted by legion 7 (see Exhibit 4) indicate chac the
ratio of BCODg to CBOD5 should be about 3.0. Other llatted data presented in
the literature suggest that this ratio ia about 1.3 to 2.0. It is suspected
Chat •any of the lower ratio values were established using data from older.
less efficient treatment plants, and that the legion V data is generally from
newer, more efficient planes. •
Vaem evaluating secondary tteatvent discharges* water quality
ilysts should use a ratio ia the raage ef 1*3 to 2.0. maless
applicable long-termCBOD tests indicate seme ether valve. The value
A-43
-------
at . .3 should generally »• «PPli«d Co *poorer" secondary plaats. «ad
2.0 should probably be applied to eb« "better", more efficient
secondary treatment planes. Analyses of vary limited sewage treatment
plane affluent BOO (eocal and carbonaceous) 5-day, long-term (ultiuce).
and time seriea data indicate that a CBOOu to CSODj conversion ratio of
about 2.3 should be uaed for nitrification facilities. Until additional
treataant plant affluent data can be collected and analysed co further
refine this ratio, a factor of 2.3 should ba uaad for nitrification and
higher-Level treatment facilities;. It Bust be emphaalxed chat this value
la presently baaed on a vary Halted set of data, and that additional treat-
ment plant effluent data is needed to gala greater confidence in the sug-
geated value. All E?A legions, the States, aad others ara strongly urged
Co voluntarily participate In a nationwide data gacharing effort so that
afire accurate ratios can be developed.
Such an effort would not be very resource intensive, aad the results
would be extremely useful. Car* should tr* taken to ensure that only the
carbonaceous deatand is sieasured. This data collection effort should include
information on the type of treatment aad type of Influent, aad the sampling
should, to the extent possible, only be performed on sanitary vaatewacers
that ara unchloreflated. This data should be submitted to EPA Headquarters
for compilation and analysis.
« „
Xt is recommended that, whenever possible, existing plant effluent
data sad/or pilot plant data should ba collected to aaaiac la the selection
of aa appropriate conversion ratio. Caution should ba exercised, however,
waoa using data from aa exiting plaat that has a Laval of treatment that
la significantly Lower than that which is propoeed. Such data should not
ba blindly applied when selecting tha appropriate conversion ratio;, it
A-44
-------
C*«.«A.A (X)
ahould a«rely b-. ueed aa a guide. A aaaaltiviey analyeia of ehe ec
rat to And 1C* implication* on ehe final ereataeae decialon to be
help eh« water quality analyse deteraiae eh* relative Importance of i
such additional data. .
iratian
It it «ijo recoaaeaded that the »00j affluent lialts ia the tr<
plant'a parmit be rev laved after the aew facility ia on-line to helj
that the. correct OOOu to dODj ratio waa applied to the aodel oucj
eaa be accoapliahed by collectiaf aad aaalyziaf appropriate plant
OOO data after the aew treataeat facility ia on-line.
(7) Feet-Aeraetoa. roafeeratioa of the efflueat to a 00
eamceatratioa of 7 af/1 abould always ba ewaloatad as aa alternative
to hifjher level* of treataeat, oalesa there ia a aita-specific
coaatraiat that precludes the tsae of polfearatioa equipaeat. Thia
tachaiqoe caa be particularly aaefal ia caaea where dilution ia low
aad reaeratioa ratea are alao low.
(•) »oapoine Soureaa. Xa aoii* eaaaa, a&a>toine aoureaa aay
prveloda aetainaane of diaaolvvd oxyfaa water
-------
source control tradeoff* aust be considered before advanced treatnent
is chosen. Site-specific evaluations should b« aid* to identify
possible nonpoint source problem*.
0. Sensitivity Analysis
th« sensitivity of conputed streaa rtspenses eo changes is
estisuted Input variables snst b« 4«e«s«itMd bcfon • final d«eijioa
of CTMCMne l«v«l« U aad*. A MacieiTiey uoMljiit eaabia*d with
judjtaant £j ••••ntial ta halp ««esbli«h graatar confidence ia the
raeults that ara obeaia*4.
lha •entitiTiey of computed (predicted) iaatraaa reeponee* to the
verioue input valuae should be detemined by repeating the caelftee
deecribed above with chancea (iacreaeea and decreaace) ia the input
variable*. The following step* ahould be followed:
1) Initially, three seta of calculation* should be sade ta reflect a
"worst," "best," and "averafe" caae for each alternative treaeaeat
level. Thi* can be aeeo«pliab«d by uaiaf aodal input value* ?h*t
reprecent, respectively, the "worst" and "base" aada of their
•anaitivity ran«ea and the value* actually selected for the aodel.
lha oatputa of these coaputatioaa should be plotted aa 00 profile*.
If all three eaaaa indicate a violation of thai watar euality
•caadard with the given level of traaeaanet %••• «»« "•*< level of
Craataant ia needed, and. no farther justification U necessary. Zf
all three cases do not indicate a violation, than the nest step
be taken.
A-46
-------
2) Next, each input variable co each equation above should be
individually increased and decreased, so that Che magnitude ol ehe
differences in predicted instream responses can be assessed, tach
input vsriable (including rate coefficients, travel tiao, physical
characteristics, etc.) should be varied over a range of values that
reflects the uncertainty in the particular variable. If direct
measurements of certain input variables are made, than ehe uncer-
tainty ia the variable would tend Co be relatively small and,
therefore, the range to be used ia ehe sensitivity analysis would
generally be-relatively small. 7ery close scrueiny should be given
to those input variable* which have no site-specific or transfer-
able data to support their having been selected. If rates (or rate
formulations) other than those suggested ia the above analyses are
used, then the sensitivity analysis should be used as pare of ehe
justification for the alternative ratea (or formulations).
The results of these sensitivity analyses (ia seep 2) should be
reviewed within ehe context of the effluent quality expected for
various treatment levels. Therefore, if the effluent requirements
determined using the range of inputs for each variable fall within
the expeceed effluent qmaliey from a single ereatment level (e.g., AST
or AST), chea additional analyses would generally not be required for
ehat variable siaaa ehe need for ehae level of ereatment is obvious.
•owever, if ehe required ereatment level is heavily sensitive to, and
dependent on, ehe selection of an input value(s) especially where
existing data are inadequaee to characeerise ehe variable(s), then a
-------
tufficiant smovnt of additional dae* shall be obtained to nor*
accurately define chat nodal v«riable(<) (thua iacreaaiaf the
confidence la that variable) «o clue cb« •election of the treatment
alternative MB be clarified. For even further confirmation of the
Mloctarf «ffittest liaieaeiooa* eh« Maaieiriej aaalfaia eaa aljo b«
ranm for Che iadiviaual iavac variablea at a leaa •eria«ent level of
•
craaeaHOC aod the roavlta aaalraa4 to deearmiae if the eaairea* veter
e^ulitr objeeeiwa emld poaaibl? be aee ae chat leaaar treaaMat
level viehia the raage of iadivioual ioavea beiag aeiliserf. It auae
be eaphiaiaea" thae the o«e of •mina' profeeaiooal jodpMoc ia
eeeeatial when evaluacias eke eaafideaee ia the ajodal ispat variable*
aaed and ia the •odaliac, reaulta obtaiaed.
To farther aaaiat ie evaluaciaf the reaalta of the «eoaitivit7
aaaljaea, the iacreaMtttal preaent worth caet Ceaaatroctioa aad 04M) of
the propeaed improved traadaeae proceaa Bay alao be eooaidered whes
deeidiaf the aeceaaary level of treaeaeat. Tor traapla, if over*ixiac
the elarifiara, providiac additional aeraeioo end elarifiers for
aitrifieatioa, or ceaaoaal eheaieal addition could provide the level
of tnraaeaaac ia e^aeationt aoch traaeaent covld be parti? juatified
baaad on beat jndfaene doe to the relatively low eoat of aaeh
additional traaeaent. On the other head, filtera (aa an add-on to
•ierifiaaeioa), dae.ta their hied iacmneatal aoee, eavld be jnetified
>7 eaia Siaylifiaai Method only if Che reevlta of theae aenaitivity
aaalyeea indicate anfficient cenfideace ia Che reaulta. Oeherviaet
• • ,
addicioaal data (iaaladiaf for calibrating and verifying the nodel)
vnnld be
-------
Generally, the variablea Co be analysed in the aenaitivity
ealayeia ahould include choae liatad below, aad anould generally be
varied by aeaaitivity raagea ia Che order of bhoee which art auggeatad
bolov (eapeeially if little or ao data ia available to aupport eh«
•«l«eeioa)t
• C80D r«t« - T»ry by about ±SO to 100X (and appropriate
iac roMiiM ia b€tv««a)f 4*f«adiat oa th« uaeartAioty ia tho
••tivatod vain*.
o BBOO rat« - vary ¥7 ••««* *23 to 73X or «or« (and
•fftoprUea iaenaoau ia b\ev««a), 4«p«a4iac oa tho
oacoruiaey ia tho ootiaweo4 valao.
• loaoration rato - *trj ly Above *tSX to ^lOOX or
Mooondinf oa tho oaeoreaiacy irn tho oocia«eo4 voiuo), cod
by iacoraodiato iacroojoau. ta appropri«to aoaaitirity
aaa\lf«ia ahoald al«o bo porfonMrf oa tho ToriabUa oood ia
tho roapoctivo roooraeioa oqaaeioa* (i.o.t Toioeity, and
alovo or dopch).
o ionthic doaumd - gooorally aho«14 uao tho aunoatod raafoo
•roaoatod iTTaecioa III(C)(4)(«l).
o Toaporaeuro, pH - oao raagoa appropriate for tho
aituatioa.
C. to«olta
1) torait Condition*. After determining tho fiaal effluent
liaitatioao aoeoaaary for tho •aintenaace of water Duality atandarda,
thooo liaieaeioaa ahould bo oaeorod iaeo tho IWtS permit. Municipel
efflmoac liaUtacioao »rj> of tea apocifiod aa 30-doy aad 7-day average
valoao for MOj, aaomio-H, and ouopeadod ooUdo. tor acre am with
•o«o flev oc eho eritiotl eoadieiooo, tho reeulta of tho DO aoalyaia
ohoII bo aood oo 7-dor average effluent liadta rather ehoa 30-day
o^orogoo, aiaco thooo oao11 atreoate are oftea vory roaotivo to
variable waoeo ia«vtoa for atreaow with aotuoro flow ot tho critical
JU49
-------
conditions, the currently adopted end applicable State or MA Region
procedures for applying modeling results to fOTV discharge permit
effluent limitation* shall be used.
Technical analyses, are being conducted which study the effect* o
effluent concentration and streamflow variability, different dilution
ratios, and the use of ai-?mative averaging period schemes on receiv
water quality. Preliminary results Indicate that effluent and stream,
variability and, to a lesser extent, differing dilutions are critical
factors which often greatly affect taa frequency of severe water qual.
violations.
A site-specific analysis that considers the effect* of the indivi
scream's flow variability, available dilution, and the selected treat:
process* effluent concentration variability on the stream's water qual
(including the frequency and severity of water quality violations) she
be performed in each case eo determine the appropriate averaging peria
Technical guidance on performing such analyses is being developed by >•
Da Office of Uater tegulaeions and Standarda to aid in the selection <
appropriate averaging perloda.
Baaed on currently available data for treatment plant performance,
fall nitrification treatment is e relatively stable process during the
sammer months', tfhen considered sogethar with streamflow variability at
dilution, this treatment process should normally preclude frequent high
levels of water quality violations whom the stream flow is at low flow
conditions and the stream's flow characteristics are not highly varlaH
A-30
-------
(t .ippaara that In aoae caaaa. «ap*cia;iy whara eha aeraaa'a
variability U not axeraaaly ht«h, fluceuaelona tn eh* affluane quality jf
full nltrificaelon facllitlaa daalgnad co achlova 30-Uay avaragt p«rmit
limitation* ara nee Ukaly Co hava a st«nU leant Upacc on cha aquae le
habieae dua eo laeraaaad loadIng* or dacraaaad dilution. Actual lapaeta
eo cha aquatic habieae or daaicnatad uaaa will ba daearmiaad whan tie*-
•pacific aaalyaa* ara eoaducead.
Th« C300 aatf HOD auepuea fro« eha 00 aoaljiia cheuU b«
ivartad ee BOOj and awBoia-M MVDCS pan&e Uadeadooa wing eha
followlac ralaeiotuhipa (aaeabliahad aarUar)t
(a) MOj • OOO/r
(whara r • tha OCJOOiBOOj ratio, for tha appropriaea
of eraaeaane, aalaeead ia tactioB I1I(C)(6),)
(b) Rl -If- RBOO/4.S7
2) Saatoaal gffluaat Liaaieaeioaa. Tha affacea of variation*
la eaap«?aeara aad flow should ba avaloaeed ea daearaiaa whaehar or
aoe oparaeiag caaea caa ba raducad eteough aaaaoaal ralaxaeion of
affloaae limieaeioaa. Tor axaapla, le U coacaivabla that ia viaear,
hi(har flowa aad lowar eaavaraeuraa voold allow for a ralaxaeioe of
BOD aad awatoola liaieaeioaa froa a toxiciey aad 00 aeaadpoiae.
OUMPU FIOBUM
C*a asavpla problaa will ba praparad aad providad eo eha uaar* of
ehia Maehod ia eha aaar fuevra.)
A-S1
-------
imnzz Ai
ME90D 701 9CTHKZVZXC O7CCXU OOUHSTUAX pi
Calcalatiac tea pi of taa atraas aftar oisiaf of apotroaa flow
with vaatovator diacharfa ia straightforward • providad chare is so»a
aiaiaal vatar ««ality i&foaucio* available om
Zt ««• b« tea* witk iafonutioa om 4ifforooc eo«bia«tioB< of
ccidicy «ad pi. Ii« «o«e 4ir«et •«eho4» ttd •isplcte eo
prucnc for « ti«plifi«4 MChodolof?* ro^airos iafot»«tio« oa pi and
•Ikaliaiey. If so pi or alkaliaicy 4«ca ic pr«««ati7 «r«il«blt for
tao POTV ad/or for ap«cr««a( ch«n « •hort-ecn procrai of eollactiag
pi ooVor *ik*liaieT
-------
ro«.uirad to reach tha tvo aad poiata (?hanolpathaiatn
«e pi 1.3. aad Mathyl Oraaga at about pi 4.3). For
aotural vatara batvooa pi 4.5 aad 1.3 (aaaaatially all
vo aaod ba coacaraod vita for thia axarciao). thara
vill b« ao paaaolphthalaia aad poiat ~ aad All of
tho aUuliaity vill b« pr«a«ae aa biearboaata ioa
(icop.
Boca eaae th« procaduro pr«a«ac«d» aa4 tha chart aa«4« vill apply
•
for ay aituaciom. Tk« iaatr««tioaa for ita aa« arc mch aiaplar to
praawt if it ia aaataad that tha oaly vatara baiaf 4aalt vith vill b«
im th« pi 4.3 to 1^ raa«a (vaich vill aanally •• tho eaa«).
Thcro art a auabar of tactaio.voa* •acho4a« ate.* for calculatisc
pi. Tha ono proaaatod hero ao«aa to bo boat "raited for thoao
pvrpoaaa. Tho chart ia takoa from "i^uatie Chotiatry" by Sci^ 4
Morsaa (Vilay Zataraeiaaea* 1970) ( aad tho approach ia a portioa of
Cho orarall approach Choy daacribo - vhich for aiaplicity la limit ad
to tho oaoal caaa vhich vaa aolactod.
Tho calcalatiom ia illoatratod by tho follovias aumpla:
o Ia a aatural vatar ayatom (or vaatavatar) vith a pi ia tha
raafo of 4.3 to 8.3. tha alk&liaity moaaurod ia all
biearbomato ioa (ICO.*) raportad ao 'am/1 aa CaCO.. Tha
Total Zaortaaic Carboa (C_) »ui eoaaiat of both ICO, "
amd aolablo CO. vhich cooxiac ia vatar ia thia pi ran«a.
(•OTXi Tho Staadard Hothoda taat for acidity voold maaaurt
ooloblo CQ.)
A-34
-------
(I)
e Tho chart roquiraa that alkaliaity b« reported ia eena of
•illiaq>iTaleata/ liter (aee/1). The eovreraiea ia aa
follows*
Alkaliaity-w4/l «• CaCOj X 1/30 •
• total laorcaaie C«rbe« (C_) mut b« ia e«ta« of
«illiaolM/lit«r (aK/l). Tow«r«r. if «• «r« vorkiac with pi
««4 alkal laity* «• a««4 aot worry «ao«t thia eaar«rsioa.
•or above cotoraiaiat tao «ei4ity or COj coacoatraciea.
o Ia a •ituatioa liko too oao boia« «4«ra«*«tf. both tlkaliaicy
am4 CL «ro eoaaorracivo (pt ia aot). Thua* vaoa tvo
waters with alfforoat eoaeoatratioaa of alkaiiaity and C.
ar« misod • tao fiaal eoaeaatratioa ia the a lead e«a bo
•otatmiaod by aiaalo saaa baljaao*
o Tho stopo arot
1. Troa mlkaliaity aad pi. dotmiao Cy for ccrtaa
aad wa«t««
2. C*lettl*c« eaaecatratioa of tlkaliaity md C. in
bloaa.
3. Ootnmiao pB of bicad tram blcad alluliaity and
lo probloa aad a calculation ahoof ar« (irca ia
Kxhibit 3. A bleak ealeaUtioa ahoot. with chart, ia alao
attached (Exhibit 6).
-------
1
I
-
Ik —
i
I
9
I
?
m f
f
1 1
X
I • •
i
MB
I
§
ft *
rt f»
3*
!•/!
-•
8
*.•?*
'i f
2 S|S
• 551 •
I
. f
i 9
n S
i
I a
i
^M*M
•k =3
o *• *
4
3"
A-37
-------
I
$
I
|
I
911
s
0°
!/I
oa
• I
3*
i
i
IM
. ! =
*r 1 <
I I
A-SS
-------
AMOIOIX AI
The results of MV data supplied by DA DO Cincinnati show chat
BOOj levels in nitrification system effluents range from BOO. 3 - 8 ng/1.
•
Testa run oo typical nitrified effluents using the Standard Methods
•00. test consistently exhibited higher than actual carbonaceous BOO. due
to nittlfication oeearrlnf dazing eha 300 CMC. lha raaaon for tha hifh;
BOD. rtsult ia that aquaoui «olutiooa containing aMoniua salts an
in tha standard BOO. teat. These ammonium salts in the presence of nitri-
fying organisms in tha nitrified effluent create an additional apearent
BOO. demand in the effluent. For this reason, data from plants with
nitrification cannot be used to predict treatment capabilities unlearn
nitrification inhibitors are used.
The Agency has proposed (December 3* 1979
an inhibitory BOOj tMt for nitrified effluents. tarly verk at the
Washington* B.C.—Filet Plant ased allyl thiouree as the inhibitory
chemical. These tests show that the BOOj meaavred for uninhibited
nitrified «ffluents is eve to three times greater than for inhibited
effluents (See Exhibit 7).
Xt is eeNrised that all treatment plants with nitrification «se
tha inhibiting chemical and report the BOOj raUes that are
determined from this method to expand the data base of plaat
operational capabilities.
A-ol
-------
1. Tetra Tech Xae. 1977. Water Quality Assessment; A Screening
Method for Nondcsignatetf 208 Areas, EPA Publication No.
EPA-400/9-77-023, August.
2. Thoaaan, 1.7. 1972. Systssw Analysis aad Water Quality
Maaageaeac. HcCrav Hill look Co., pp 65-122.
3. Strecter, l.tf. aad C.I. Phelpo. "A Scurfy of the Pollution and
Natural Purification of th« Ohio liv«r, XII, Factors
Coaeara«4 ia tb« Ph«oomoa of Oxidation and Uaaration",
O.S. Public Haalch Sorvico, Public Boalth lullotia No. U6.
4, Covar, A.P. 1971. W8«loceiaf th« Propor UMration Co«ffici«at
for ««o ia tfatar Qualify Moo«l« , pmsoatod at tho ETA
Coofarcaea on Caviroaaaatal Kedaliaf aad $£m»lation, April.
3. lenaett, J.P. aad I.E. lathbua. 1972. "leaeration ia Open-
Channel Plow, Ceological Survey Professional Paper 737".
6. lathbua, I.E. 1977. "leaeration Coefficieats of Sen
State-«f-the-Art", Journal ••:( the Hydraulics Division, A5CZ,
Vol. 103 No. BT4, April.
7. Tsivoglou, E.C. aad J.I. Wallace. 1972. "^Characterization of
Stream leaeration Capacity", 9.S. Eavirunsiantal Protection
Agency, leport No. EPA-R3-72-012, October.
8. Grant, l.S. aad Skavroneck. 1980. Comparison of Tracer Methods
aad Predictive Equations for Determination of Stream
leaeratioa Coefficieats oa Three Small Streams ia Wisconsin.
O.S. Geological Survey, Water Resources Investigation 80-19,
March.
~9. Personal Communication with Dr. Ernest Tsivoglou, March 26, 1980.
10. Personal Communication with Maan Osmaa, tipper Oletangy Water
Quality Survey, Ohio EPA, September 1979.
11. Phciffer, T.B., L.J. Clark, aad N.L. Lovelace. 1976. "Patuxent
liver laaia Model, Rates Study", Preaeated at EPA Coafarence
oa Environmental Modeliag and Simulation*, April.
A-63
-------
12. Peraeaal Communication wish 3r. T.P. Chang. 1979. Weat Fork si
Hue liver Water Quali:/ Survey, Indiana State Beard of
Health, September.
13. Hydroacieace lac. 1971. Simplified Mathematical Modeling of
Water Quality. EPA, March.
14. laytheea Co. 1974. Oceaaegraphic aad Environmental Servicea,
Expanded Development of BUAM-A Mathematical Medal of Water
Quality for the Beaver liver Baa in. Si*. Contract No.
68-01-1836, May.
15. Tetra Tech Inc. 1978. lataa, Coaatanta, aad Kiaetic Formulationa
ia Surface Water Quality Modeling. OA Publication jio.
EfA-400/3-78-103,
16. EPA, legion 7, Eaatera Oiatrict Office, Diachargera Pilea.
17. Peraoaal Commuaicatiea with Mark Tualer, Water Quality Evaluation
Section, Wiaconaia Deparcaaat of Natural laaeurcea, October
17, l»7f.
18. Opper Miaaiaaippi liver 208 Crane Water Quality Modeling Study.
Hydroacieace Inc., January 1979.
19. Peraeaal Communication between E.O. Oriacell aad 1.7. Themann,
Auguat 1980.
20. Taiveglea, E.C. aad L.A. Real. 1976. "Tracer Meaauremeata of
leaeratioa: IZZ. Predictiag the leaeratioa Capacity of
Inland Stream*". Journal WPCT. December.
- 21. Wright, l.M. aad A.J. McDonnell. 1979. "la-Stream Oeoxygtnatioa
late Prediction", ASCZ Journal of the Environmental
Engineering Diviaioa, April.
22. Peraeaal Cumminieation with 1.P. McGhee, EJA legion 17,
Auguat 1980.
-------
-------
(SB)
^^1^
\ UNITIO STATES INVIRC3N MENTAL PROTECTION AQINCY
WASMIMOTOM. 9.6. X04«0
JUN25 911
HEMDRAHOUM
SUBJECT: Mdtndun to Simplified Mathematical Modeling Methodology
FROM: Steven Schatzow, Director,
Office of Water Regulations and Standards (UH-551)
UteSS^^&s&tZLjJ*--
Henry U Longest II. M rifctor
'ice of Water Program operations (WH-546)
0
TO: Regional Hater Division Directors
Regional Environmental Services Division Directors
Regional Kasteload Allocation Coordinators
Attached, for national use, 1s the final version of the addendum to
the 'Simplified Analytical Method" which provides several technical
revisions or clarifications to the national guidance document -dated
September 26, 1380. The guidance provided 1n this addendum will supersede
that 1n the respective sections of the original document.
As you will note, the addmdum provides modifications related to the
following Issues:
application of the guidance.
performing ammonia toxlclty analyses.
calculation of stream travel time to reach the point
of critical dissolved oxygen deficit. »
temperature correction factor for £3.
dissolved oxygen saturation concentration determination.
conversion ratio of G8QOU to C800$.
permit conditions.
These changes are based on additional Information and analyses which have
available.
If you have any questions or comments or desire additional
Information, please contact T1m w. Stuart, Chief, Monitoring Branch,
Monitoring and Data Support Division (WH-5S3) on (FTS) 426-7766.
Attachment
-------
UNITED STATES ENVIRONMENTAL PROTU-mON AGENCY
WASHINGTON. D.C. 2O44O
ADDENDUM
TO .
•S1«pl1f1td Analytical Method for Determining
NPOES Efflutnt Limitations for POTW's
Discharging Into Low-Flow Streams: National Guidance"
I. INTRODUCTION
This addendum provides Mvtral technical revisions to the "Simplified
Analytical Method" that clarify, correct, or modify (based on additional
Information and analyses which have become available) certain sections of
the original national guidance document dated September 26. 1980. The
guidance provided herein supersedes that 1n the respective sections of the
original document*
Users of this method (as well as others) are strongly encouraged to
develop additional data and other Information on reaction rates and other
factors applicable to this method, and to submit this additional data and
other Information, along with suggested Improvements for the method, to:
Chief, Uasteload Allocations Sect4on
Monitoring Branch
MOSO/OWRS (WH-553)
U.S. Environmental Protection Agency
401 M Street, S.U.
Washington, O.C. 20460
(Telephone: (202)-426-7778)
This additional data and other Information Is needed so that appropriate
additional Improvements to the method can be made periodically. Users may
.also, when appropriate, make any modifications to this method that will
allow the method to more accurately represent regional or local
conditions. Any changes should be supported with an adequate technical
justification. Including sufficient applicable data.
Where the results of the water quality analysis Indicates the need for
treatment beyond secondary. State users of this method are encouraged to
coordinate the modeling analysis with a review of the environmental
benefits and costs of the receiving water's applicable water quality
standards. Such assessments should be conducted In accordance with the
revised water quality standards regulations and EPA guidance, when
published.
-------
A site-specific analysis th«t eonsldtrs the effects of the Individual
strtui's flow variability, available dilution, and tht selected treatment
process1 affluent concentration variability on the strain's water quality
(Including tht frequency and severity of water quality violations) should
bt ptrforwd 1n each cast to datanalnt tht approprlatt averaging ptrlod.
Technical guidance on performing such analysts 1s being developed and will
soon be released (anticipated date Is about July 1982) by the EPA Office
of Water Regulations and Standards to aid In the selection of appropriate
averaging periods.
Based on currently available data for treatment plant performance,
full nitrification treatment is a relatively stable process during the
summer months. Hnen considered together with strtamflow variability and
dilution, this treetawnt process should normally preclude frequent high
levels of water quality violations when the stream flow Is at low flow
conditions and the strata's flow characteristics are not highly variable.
It appears that 1n east cases, especially where tht strata's flow
variability 1s not extremely high, fluctuations In tht effluent quality of
full nitrification facilities designed to achieve 30-day average penalt
limitations are not likely to have a significant Impact on the aquatic
habitat due to Increased loadings or decreased dilution. Actual Impacts
on the aquatic habitat or designated uses will be determined when
site-specific analyses are conducted.
-------
Woto»-S«turoud Air (mq/t) *•
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7.11
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7JI
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7JO
7.T7
749
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4.71
441
471
440
4.71
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4J1
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4.12
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419
410
401
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343
3.74
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*49
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ACS
ac
-------
E. Initial Deficit Determination freqe 18 and Exhibit 3).
The dissolved oxygen (00) situ Pit 1 on eonetntritlons tablt presently
Ineludtd u Exhibit 3 In tin Method Is based on Strttttr. Additional
evidence which his bttn accumulated Indicates that these sit u pit 1 on 00
values IPI not entirely iccupitt. The new 15th edition of 'Standard
Methods' contains in updated UbU of saturation 00 conctntPitlons which
represents tht Most up-to-datt and accurate saturation DO eoncantPitl on
data currently available. This table 1s reproduced in Attachment A of
this addanduB. It should bt notad that tht tabulated values for 00
saturation art for distilled water at standard prtssurt (saa level).
Thtst valuts should bt eorrtettd for altitude and dissolved sol ids levels
tht formula at tht bottom of tht tablt*
It 1s Important for all wasttload allocation and other water quality
modeling efforts to be consistent In tht use of saturation 00 values. Use
of the attached table Is recomended for this Method (and other modeling
efforts) because It represents the best Information currently available.
F. Conversion from CBOOu to B00< fpaot 18).
(i) Tht method presently discusses conversion ratios of C80DU to 800$
for virlous levels of treataent; however. 1t Is unclear whether the method
Is referencing carbonaceous (based on a n1trlf1cit1 on-Inhibited test) or
total (based on an uninhibited test) 800$. Therefore. It should be
clarified that the ratios being discussed In the guidance are for C800U to
CBOOj (based on a nitrification-Inhibited test). (It 1s recoieiended that
the permit BOO effluent Units which ire finally selected after the water
quality analysis be written is i carbonaceous and not i total 8005; the
use of CBOOs effluent Halts ind, coppe:;and1ngly, i carbonaceous
(tnhlblted) 800 test when Monitoring the effluent can help avoid potential
data Inaccurzdes that can result fpoa nitrification occur! ng 1n the
bottle during an uninhibited BOO test due Co the presence of sufficient
nltriflers 1n the test bottle.)
(b) The CBOOu *° CSOJs ratio Is a function of the level of treatment
and the associated degradabl 1 Ity of the waste. Thus higher ratios ipe
expected and have been observed for higher levels of treatment since the
C800 remaining 1n more highly treated effluents degrades «ore slowly than
that In less treated wastawaters.
Th« method presently suggests that, for plants with treatment levels
greater than secondary, a ratio of 2.5 to 3.0 should be used for
determining permit limitations. The guidance Implied, though did not
specifically state, that 2.5 should be u«ed for nitrification levels of
treatment and a ratio of approximately 3.0 should be used for treatment
levels greater than nitrification.
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Additional analyses of very limited sewage treatment plant effluent
BOO (total and carbonaceous) 5-day, long-term (ultimate), and time series
data Indicated that a CBOtL to CBOOs conversion ratio of about 2.3 should
be used for nitrification facilities. Until additional treatment plant
effluent data can be collected and analyzed to further refine this ratio,
a factor of 2.3 should be used for nitrification and higher-level
treatment facilities. It must be emphasized that this value Is presently
based on a very limited set of data, and that additional treatment plant
effluent data 1s needed to gain greater confidence 1n the suggested value.
All EPA Regions, the States, and others are again strongly urged to
voluntarily participate 1n a nationwide data gathering effort so that more
accurate ratios can be developed.
It Is recommended that, whenever possible, existing plant effluent
data and/or pilot plant data should be collected to assist 1n the
selection of an appropriate conversion ratio. Caution should be
exercised, however, when using data from an existing plant that has a
level of treatment that Is significantly lower than that which 1s
proposed. Such data- should not be blindly applied when selecting the
appropriate conversion ratio; It should merely be used as a guide. A
sensitivity analysis of the conversion ratio and Its Implications on the
final treatment decision to be made can help the water quality analyst
determine the relative Importance of gathering such additional data.
It Is also recommended that the BOO; effluent limits In the treatment
plant's permit be reviewed after the new facility 1s on-Hne to help
ensure that the correct C800U to CBOOg ratio was applied to the model
output. This can be accomplished by collecting and analyzing appropriate
plant effluent CSOO data after the new treatment facility Is on-Hne.
- 6. Permit Conditions (page 22).
The guidance presently requires that, for streams with zero flow at
the critical conditions, the results of the modeling analysis should be
used as 7-day average effluent limits, and, for streams with nonzero flow
at the critical conditions, the currently adopted and applicable State or
EPA Regional procedures for applying modeling results should be used. The
original guidance also Indicates that this Issue of applying modeling
results to effluent limitations 1s being analyzed 1n support of the
development of forthcoming policy guidance on wasteload allocations/total
maximum dally loads (ULA's/TfCL's).
Technical analyses are being conducted which study the effects of
effluent concentration and streamflow variability, different dilution
ratios, and the use of alternative averaging period schemes on receiving
water quality. Preliminary results Indicate that effluent and streamflow
variability and, to a lesser extent, differing dilutions are critical
factors which often greatly affect the frequency of severe water quality
violations.
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XX. TECHNICAL REVISIONS
A. Applications and Constraints (page 3).
As stated 1n the original guidance doeuntnt, the analytical ttchnlqucs
which art used 1n water quality modeling should be tht simplest possible
that will still allow tht water quality manager to make confident and
d«ftns1b1t wattr pollution control decisions. In nany cases, where
relatively simple conditions exist, simplified node11ng efforts that have
•1n1«al aanpower and data requirements are often adequate to make such
decisions. Use of simplified efforts, when appropriate, can result 1n
both substantial savings 1n State and EPA resources and cost-effective and
technically sound effluent limitations to be achieved.
Recent experience and analyses Indicate that this simplified method,
when followed properly and with little or no site-specific data being
employed,' should normally result In both technically sound water quality
justifications being developed for nitrification levels of treatment and
substantial savings In State and EPA resources. However, It has also been
noted that this simplified analysis alone (I.e., without any site-specific
data) usually cannot provide the confidence needed to adequately justify
permit limits more stringent than about 10 mg/1 CBOOj and 1.5 mg/1 NHj-N,
Including relatively costly filtration treatment after nitrification.
Therefore, tnls simplified method cannot be used by Itself to justify
permit limits nore stringent than 10 «g/1 CBOOs and 1.5 mg/1 NHj-N
(Including filtration after nitrification).
Where treatment sore stringent than 10 mg/1 CBOOg and 1.5 ng/1 NH3-N
(Including filtration after nitrification) appears to be needed,
appropriate supporting site-specific data should be collected «nd used In
the analysis 1n order to Increase confidence 1n the variables ust* 1n this
model. In the the modeling results that are obtained, and, most
Importantly. In the treatment decision Itself. This additional level of
analysis should also be accompanied by a rigorous sensitivity analysis
(see page 20 of the method). Based on past analyses and construction
grant project reviews, 1t appears that this situation (e.g., the need for.
treatment beyond nitrification) will seldom be required except 1n certain
cases where small streams with very low assimilative capacities tre
encountered.
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8. Ammonia Toxldty Analysis (page 5). __
The original guidance document recommends that, 1f no un-lonlzed or
.total ammon1a-N standards are available for use, a criterion of 0.02 wg/1
un-lonlzed ammonia be used for freshwater cold water habitats, or O.OS
mg/1 un-1on1zed ammonia be used for freshwater warm water habitats.
Additional research, however, Indicates that these criteria may 1n many
cases be more stringent than necessary to protect water quality. It 1s
now recommended that the latest EPA ammonia toxldty criteria, when
promulgated, be used In conjunction with the supporting ammonia criteria
Implementation guidance document. Until the new EPA ammonia toxldty
criteria are promulgated, AT facilities proposed solely to prevent ammonia
toxldty may be approved only with supporting justifications based on
either: (1) site-specific biological data showing that the designated uses
cannot be restored without redudng ammonia toxldty, or (2) bloassay data
(either from a laboratory or similar site) for Indigenous species showing
that existing or future ammonia toxldty levels will Impair designated use
attainment (exposure levels and durations for these tests should be
similar to those occurring or anticipated to occur In the receiving
water). (Note: After publication of new ammonia toxldty criteria by EPA,
Advanced Treatment processes proposed solely to prevent ammonia toxldty
may be approved consistent with these criteria and this simplified
method.)
C. Pissolved Oxygen Analysis (page 9). .
Equation 5 on page 9 of the method Is presently written incorrectly.
The correct form, which should be used, 1s:
in C(K2/KflOO) (1-
(Eq. 5)
0. Temperature Corrections of Reaction Rat** (pages 17-18).
The method presently states that the temperature correction
coefficient (•) for *3 to be used 1n Equation 10 Is 1.10. A more
reasonable correction coefficient for 1(3, which should be used, 1s 1.08.
This latter value represents an average of the range of correction factors
found by different researchers ("Rates, Constants, and Kinetics
Formulations 1n Surface Water Quality Modeling', EPA-600/3-78-105).
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