NC0004979_Storm Water Discharges_19960408

- DRAFT -
Permit Requirements for Stormwater Discharges from
Oil & Petroleum Storage Facilities
Background/ Introduction
The Permits and Engineering Unit reviewed NPDES permit monitoring requirements for stormwater
discharges at oil terminal facilities located in the Greensboro and Charlotte areas. This review revealed
inconsistencies in monitoring, requirements. These inconsistencies were discussed with staff of the
Winston-Salem and Mooresville regional offices. These discussions and a review of past information
collected at these facilities form the basis for the standard monitoring requirements'contained in this
Standard Operating Procedure (SOP) for Stormwater Discharges from Oil Terminal Facilities. Examples
of effluent monitoring sheets are included at the end of this SOP. One sample effluent sheet is for oil
terminal facilities that discharge to water supply classified waters, while the second effluent sheet is for
facilities that discharge to non -water supply classified waters.
Review of oil terminal facility permits also indicated that wastewater sources were not always identified,
thus, the State will request that the oil terminal facilities characterize their wastewater sources.
Specifically, the State will request plans delineating the oil terminal and identifying wastewater sources
for each region within the oil terminal facility. This delineation will also specify different wastewater
treatment methods for different wastewater sources (if appropriate). This information request will be
included in the cover letter accompanying the draft permit. It is the intent that information gathered may
be incorporated into the final permit.
I. Minimum Requirements for ALL Oil Terminal Facilities
A. Flow
Measurement of flow is to be representative of a discharge event. Many oil terminal facilities
have storage ponds to collect runoff and therefore, discharges may not always occur during
storm events. Flow should be monitored by one of the following methods:
1) Measure flow continuously, or
2) Calculate flow based on the area draining to the outfall, the built -upon area, and the total
rainfall, using the rational equation (see below), or
3) Estimate by flow measurement at 20 minute intervals during the entire discharge event, or
4) Base flow on pump logs.
The rational equation: Q=KuCIA, where
Q=flow (peak flow rate (cfs or m3/sec)
Ku=units conversation factor = 1.008 for U.S. standard units (usually ignored because it
is so close -to 1), or 0.278 for SI units
C= dimensionless runoff coefficient for the watershed, loosely defined as the ratio of
runoff to rainfall
I=intensity of rainfall taken from the intensity -duration -frequency. curves for the specified
design return period at the time of concentration tc, (in/h or mm/h)
tc=time of concentration - time after the beginning of rainfall excess when all
portions of the drainage basin are contributing simultaneously to flow at the outlet
A=area of tributary watershed (acres or km2)
is used to calculate the runoff from a region, given the runoff coefficient which accounts for
infiltration and other potential losses in the region, the rainfall intensity, to the region, the time it

B. Benzen--_
Daily w
Bcnx--,
slipp!
anatv!-'i�:
violwWr,
recclv_,:.
no
WLi!
REFERE TI", —
Dodson, P ­
Er .
Linville, R�,n.
C11;
USEPA.
E111
April 8, 1996
Page 6
0, receiving stream under average flow conditions
risk to humans consuming
n'/.c n e in waters classified as water
of past data, a reasonable potential
potential for a water quality standard
1. 9 Clli:'/I multiplied by the dilution of the
-�Jizm rl to two significant digits). If there is
i i &,requirement.
o !h�_" )24/6)25 series semi-annual monitoring
i,,r supply classified waters. In non -
'M 1-:11111UL11 monitoring is required.
!%/h: 1,hod Is Most Rational?. Civil
el. --hone conversation with P.
Control.
, il I

April 8, 1996
Page 2
takes for runoff to travel from the region's upper reaches to its outlet, and the region's drainage
area.
For oil terminal facilities with large storage ponds that serve to collect runoff, item no. 2 listed
above and the rational equation should not be used because the calculations will determine the
flow to the storage pond, rather than the flow from the pond.
B. Acute Toxicity - Fathead Minnow (Pimephales promelas) 24 -hr, Episodic
Monitor annually (assuming first five discrete storm events have already been monitored and
showed no toxic effects)
Monitoring Footnote: acute toxicity monitoring should occur during one of the two semi-
annual EPA Methods 624/625 monitoring events (see item E below).
Products stored at oil terminals may contain a variety of different chemicals (some of which
may have harmful or toxic effects). To verify that toxic chemicals are not discharged to
surface water, a periodic toxicity test will be required. An acute, rather than chronic, toxicity
test is required because oil terminal facility discharges are typically short-term, episodic
events. Specifically, an acute 24-hour pass/fail at 90% waste concentration using fathead
minnows is the recommended toxicity test for stormwater discharges.
Facilities that meet one or ,more of the following criteria will not qualify for annual
monitoring and will be required to monitor for acute toxicity during five storm events:
1) Facilities that have never monitored for acute toxicity during a storm event, or
2) Facilities that monitored for acute toxicity during four or fewer storm events during the last
permit period, or
3) Facilities that completed five acute toxicity tests during five storm events, but did not pass
all five tests.
Facilities that fail an acute toxicity test conducted during one or more of the five storm events or
during an annual monitoring event will be required to conduct quarterly monitoring for the
forthcoming permit period, and must .receive State approval for reduced monitoring. For
facilities that have not yet conducted acute toxicity testing for the first five discrete storm events, a
statement in the permits will allow for additional toxicant limits should the toxicity. test indicate
toxic effects. At the time of permit renewal, only annual monitoring for toxicity would be
required if the facility has performed the five discrete sampling requirements with no acute
toxicity.
C. Total Suspended Solids
Monitor monthly
Daily maximum 45.0 mg/1
Historically; TSS has not been a significant problem in stormwater discharges at oil terminal
facilities. An analysis of TSS data from five stormwater dischargers indicated only one event in
excess of the permitted 30.0 mg/l monthly average. Should TSS monitoring data indicate any
substantial problems, the Regional Office may elect to enforce the instream standard for turbidity.
D. Oil and Grease
Monitor monthly - No Limit
Monitoring Footnote: Where possible, the grab sample for oil and grease should be skimmed
from the water surface of a quiescent (calm water) zone.

In cases when. i
be require;' f'(.)
potential
violation,
111. Add --'1o'--- I
A. Pheno!:!:1,'
Phenol:
4-c
2,
2, 5
2,(,,-
3,
2, J.
2,4,
2, 3,
-
2-;r,
3 -
3 -
Plif.'n", --
cal
is
fis
ph
fol
WC11.,
As
po`-:si
fo I.
pr'
at
1V
c 1;'
Cl-, 1,
w'.
be
April 8, 1996
Page 5
1;61 it requirement, monthly monitoring should
in he obtained and a second reasonable
potential for a water quality
Supp!y (WS) Waters
S rr )n?.1;tor for separately)
st-parateIy)
for separately)
-'n for separately)
r for separately)
s'or separately)
`series, monitor for separately)
--iiS series, monitor for separately)
SO
series, monitor for separately)
�
1,t and should not be grouped in the same
lvcr!cntly done in the past). Phenol
ci le.niiipals, can result in tainting of
M drinking water. In addition,
i n water treatment facilities to
111' i,,heiiol into water supply classified
q oiid their concentration in drinking water.
(),tl ti�rniiiial facility discharges and the
''I -ed on a monthly basis in water
F U) pg/l. There is limited toxicity data
cL supplies from taste and odor
r. 1 s o l.' netroleurn compounds stored
!I he established (if necessary).
C!, 1 or i liated phenols in water supply
:red semi-annually at oil terminals that
."-Y!"S Mch,idcs phenol and some, but not
r,:1 C11 0 1 Under the 624/625 series is
cif "ch lor;,-atcd phenol formation in water
;:1111Uad monitoring will be required for
Yc-ics) only in water supply classified
it is known that they can

April 8, 1996
Page 3
Historically, oil and grease has not been a significant problem in stormwater discharges at oil
terminal facilities. H¢wever, it is suspected that the samples are typically collected using an
inappropriate sampling method. Where possible, oil and grease samples should be skimmed
from the surface of a quiescent zone closest to the discharge. This is often difficult to achieve
given the nature of stormwater discharges.
E. EPA Methods 624 land 625 (Base/Neutral and Acid Extractables)
Monitor semi-annually (assuming no reasonable potential - see Section II)
Historical data indicate that organics are not discharged at concentrations greater than water
quality standards. However, because products stored at oil terminals may contain different types.
of organic chemicals, there exists the potential for organics to be released at these facilities.
Semi-annual monitoring is recommended to develop a database documenting the amount and
types of organics potentially released from each site. More frequent monitoring would be
required if the reasonable potential for a water quality standard violation is demonstrated (see
Section II).
F. Tank Solids, Tank Bottom Water, and Rag Layer
No direct discharge of tank solids, tank bottom water, or the rag layer is permitted.
There are typically four discrete layers of varying thicknesses (see diagram) within a terminal
tank. At the very bottom of the tank is the solids layer which achieves a 1/2-1 inch thickness
over a 5-6 year period. Immediately above the solids layer is 1-6 inches of tank bottom water
which results from rain water breaching the wall seal in open roof tanks. Open roof tanks are not
completely open, but have a roof floating directly on the product. There is a seal between the
tank walls and floating roof designed to prevent water from entering the tank. Water breaching
this seal and entering the tank is referred to as tank bottom water. The rag layer is at most 3/4
inch thick and forms the interface between the tank bottom water and the product. The product is
the topmost layer and is 20-25 feet. Normally, the tank bottom water is removed from the tank
when it is 3-4 inches deep. The mixture of water and product in the rag layer is often drawn off
when tank water is removed because water entering tanker trucks must be minimized. As a result
of potentially high levels of organic compounds in the three bottom layers of storage tanks, they
are not to be discharged,. but instead should be transported off-site for appropriate treatment
and/or disposal or treated/recovered onsite if treatment technology capabilities occur onsite.
G. Hydrostatic Testing
Hydrostatic testing of oil tanks normally occurs once every five or six years. Prior to the
hydrostatic testing, the tank is completely drained and tank bottom materials are handled as
described in the previous section. The tanks are completely cleaned and then coated and welded
(if necessary). The tank is then filled with water for the hydrostatic test. Some oil terminal
facilities use stream or lake water to hydrostatic test their tanks, while others use potable city
water. Because the tank is thoroughly cleaned prior to refilling with water for the hydrostatic
test, water discharged from the tank following the hydrostatic test should be fairly clean.
However, tank discharges following hydrostatic testing may contain contamination. 'Therefore,
monitoring of the tank water prior to direct discharge will be required. There shall be no direct
discharge from oil terminal facilities following hydrostatic testing if concentrations of benzene
and/or toluene are greater than their respective water quality standards (see effluent pages at end
of SOP for details).

II. Additiepa1! ,
The reason!)±,',.
violate ,. -
determ i P' :.
monito ri, . L,
quality sian .-
.
effluentconc.­ ...
Reasonable no!
that has ci, r
works he,, :
point;
maxim , ; r.
for do .
detenu ' .
April 8, 1996
Page 4
i"I 6n Reasonable Potential
.! ! cictermine the potential of a discharge to
_ d on existing data. If a parameter is
_i ! C I_ CI Liality standard, a limit and monthly
} t I vc reasonable potential to violate a water
t concentration is greater than the allowable
tical analysis for each parameter of concern
rci. 1 cn- eacli parameter, the statistical analysis
nis (from DMRs) although the more data
P! : ,tical amilysis allows one to calculate a
1'."IstiII2 data set. A step-by-step procedure
n . i ted based on reasonable potential
charas
4
STEP
l
2
;:I .,fc;ssional judgment should be used by the
P V
t1Ier will not be determined statistically,
3 �'
;'✓/i�IAI�
4 r
I," used by comparing the number of
5 I
) ,y tI tc multiplication factor determined
Ira Lion.
6
: c t d c, ffluent concentration) with the
zl.
t ir,strcam dilution and the corresponding
a
I ner,nitting authorities find reasonable
„nc�,ntration is greater than the allowable
l• '
A sprea&'­­�'
'i i.. It is titled "Toxicant Spreadsheet" and is
located on
! n t, t o f the facility name and permit
numbcr, t
. m, fcacral water quality standard, and
the MI..:'
t ;!ren computes the standard deviation,
mean, a :
_ts. he coefficient of variation is then
used `, h � -
I, t h u spreadsheet) to determine the
Multip l
; ! c > "Fox icant Spreadsheet to calculate
the maxi
If the ma..i
, ,; th;tn or equal to the allowable effluent
concen tri.
n c, t ti t i al for a water quality standard
violation;, t
nd monitored on a monthly basis.
The dc} ;.,
zt naram,,eter multiplied by the dilution of
the recinogens.
Average flow should be
used
If o f a,_ '
I
i I, I'S gar o U 1, d be obtained over a five-year
perm 1:
r o !'(-'I ata points which will accurately
charas
4

April 8, 1996
Page 4
II. Additional Site -Specific Requirements Based on Reasonable Potential
The reasonable potential procedure is a method used to determine the potential of a discharge to
violate a water quality standard for a given parameter based on existing data. If a parameter is
determined to have reasonable potential to violate a water quality standard, a limit and monthly
monitoring will be required. A parameter is determined to have reasonable potential to violate a water
quality standard if a calculated maximum predicted effluent concentration is greater than the allowable
effluent concentration.
Reasonable potential is determined by performing a statistical analysis for each parameter of concern
that has either a state or federal water quality standard. For each parameter, the statistical. analysis
works best with a minimum of eight to twelve data points (from DMRs) although the more data
points used, the more accurate the analysis. The statistical analysis allows one to calculate a
maximum predicted effluent concentration based on the existing data set. A step-by-step procedure
for determining whether or not a parameter should be limited based on reasonable potential
determination follows:
STEP
1 Determine the number of sample points (n)
2 Determine highest value from data set. Best professional judgment should be used by the
reviewer so as not to use an outlier. Since an outlier will not be determined statistically,
maximum values should rarely be discarded in this analysis.
3 Determine the coefficient of variation (CV = STD DEV/MEAN)
4 Determine the appropriate multiplication factor to be used by comparing the number of
samples versus the co -efficient of variation (see Table 3-1)
5 Multiply the highest value from the data set (Step 2) by the multiplication factor determined
in step 4 to obtain the maximum predicted effluent concentration.
6 Compare the value from Step 5 (the maximum predicted effluent concentration) with the
allowable effluent concentration, which is based on instream dilution and the corresponding
water quality standard. EPA recommends that permitting authorities find reasonable
potential when the maximum predicted effluent concentration is greater than the allowable
effluent concentration.
A spreadsheet has been developed to expedite this analysis. It is titled "Toxicant Spreadsheet" and is
located on the NPDES server. The spreadsheet requires the input of the facility name and permit
number, the waste flow (QW), 7Q10 flow, pollutant name, state or federal water quality standard, and
the DMR data points with appropriate units. The spreadsheet then computes the standard deviation,
mean, and coefficient of variation for the entered data points. The coefficient of variation is then
used along with n (the number of data points entered in the spreadsheet) to determine the
Multiplication Factor. This Multiplication Factor is entered into the Toxicant Spreadsheet to calculate
the maximum predicted concentration.
If the maximum predicted effluent concentration is greater than or equal to the allowable effluent
concentration, (or in other words, if there is reasonable potential for a water quality standard
violation), the parameter should be limited (as a daily maximum) and monitored on a monthly basis.
The daily maximum limit shall be equal to the standard for that parameter multiplied by the dilution of
the receiving stream under summer 7Q10 conditions for non -carcinogens. Average flow should be
used for carcinogens and 30Q2 flow should be used for aesthetic standards.
If a facility monitors semi-annually (twice/year), 10 data points would be obtained over a five-year
permit period which is slightly more than the minimum number of data points which will accurately
characterize an effluent discharge (USEPA March 1991).

Historically, oll r
term i!,.•,'
inapp!•�)_,
fro m t
given
E. EPA
Monitor . ;
April 8, 1996
Page 3
• ;i ic•4nt problem in stormwater discharges at oil
t samples are typically collected using an
i l and grease samples should be skimmed
(h,- 111scharge. This is often difficult to achieve
=r" a- .0 Acid Extractables)
potcJitial - see Section II)
Historical ct:)t; ! . t c isch trged at concentrations greater than water
qual i t t .: c l at "I
l terminals may contain different types
Of (It ! .. • i,.-. s to be released at these facilities.
Suri !:ff) N database documenting the amount and
P.Zore frequent monitoring would be
reyv :I y standard violation is demonstrated (see
See i io;..
F. Tpnk :::
,.,h5 _
ayer
No dircct c1:..... •
!: a an r,'
or the rag layer is permitted.
There ;ir-
f•,,, '
!Cl<nesses (see diagram) within a terminal
tan"I.
'
•„ •r Which achieves a 1/2-1 inch thickness
ovci, a _
4
::)yer is 1-6 inches of tank bottom water
wh
MC
�ncn roof tanks. Open roof tanks are not
co+
tic testing if concentrations of benzene
`u" product. There is a seal between the
tale.
of :::
;"rom entering the tank. Water breaching
this
I
nttom water. The rag layer is at most 3/4
inch t' :'.:
, h
! ,gym water and the product. The product is
the !; -;:
hottom water is removed from the tank
wbcj" i:> _.
!
; roduct in the rag layer is often drawn off
-:Cr trucks must be minimized. Asa result
of Polo
e bottom layers of storage tanks, they
arc,•
rtcd off-site for appropriate treatment
an.":,,
,•` hnology capabilities occur onsite.
G. Hyde :, -
il_c every five or six years. Prior to the
' tank bottom materials are handled as
l y c leaned and then coated and welded
hydrostatic test. Some oil terminal
fac :1 i t
i r t a n ks, while others use potable city
refilling with water for the hydrostatic
test,
;/clrostatic test should be fairly clean.
He
M> Iy contain contamination. Therefore,
MC
he required. There shall be no direct
dist,:,:
tic testing if concentrations of benzene
� ! T;; i t y standards (see effluent pages at end
of :::

April 8, 1996
Page 5
In cases where a facility requests reconsideration of a limit requirement, monthly monitoring should
be required for at least 10 months so that 10 data points can be obtained and a second reasonable
potential calculation can be conducted. If there is no reasonable potential for a water quality
violation, monitoring should be reduced to semi-annually.
III. Additional Monitoring Requirements For Water Supply (WS) Waters
A. Phenol and Chlorinated Phenols
Phenol: Monitor monthly.
Chlorinated Phenols: Monitor semi-annually
3 - chlorophenol (not included in 624/625 series, monitor for separately)
4 - chlorophenol (not included in 624/625 series, monitor for separately)
2, 3 - dichlorophenol (not included in 624/625 series, monitor for separately)
2, 5 - dichlorophenol (not included in 624/625 series, monitor for separately)
2, 6 - dichlorophenol (not included in 624/625 series, monitor for separately)
3, 4 - dichlorophenol (not included in 624/625 series, monitor for separately)
2, 4, 5 - trichlorophenol (included in 624/625 series)
2, 4, 6 - trichlorophenol (included in 624/625 series)
2, 3, 4, 6 - tetrachlorophenol (not included in 624/625 series, monitor for separately)
2 - methyl - 4 - chlorophenol (not included in 624/625 series, monitor for separately)
3 - methyl - 4 - chlorophenol (included in 624/625 series)
3 - methyl - 6 - chlorophenol (not included in 624/625 series, monitor for separately)
Phenol and chlorinated phenols are separate and distinct and should not be grouped in the same
category when determining discharge limits (as has been inadvertently done in the past). Phenol
is a common component of petroleum compounds stored in terminals, can result in tainting of
fish tissue, and can cause taste and odor (organoleptic) problems in drinking water. In addition,
phenol discharged from terminals could combine with chlorine in water treatment facilities to
form chlorinated phenols. Limiting the discharge of phenol into water supply classified
waterbodies could reduce chlorinated phenol formation and their concentration in drinking water.
As a result of the expected occurrence of phenol in oil terminal facility discharges and the
possibility of chlorinated phenol formation, phenol will be monitored on a monthly basis in water
supply classified waters.
Chlorinated phenols have a state water quality standard of 1.0 µg/1. There is limited toxicity data
for chlorinated phenols, thus, the 1.0 µg/1 standard protects water supplies from taste and odor
problems. It is unlikely that chlorinated phenols are components of petroleum compounds stored
at terminals, however, data must first be collected before limits can be established (if necessary).
Monitoring will only be required on a semi-annual basis for chlorinated phenols in water supply
classified waters.
The EPA Methods 624/625 monitoring series is required semi-annually at oil terminals that
discharge into waterbodies of any classification. This series includes phenol and some, but not
all, of the chlorinated phenols. Semi-annual monitoring for phenol under the 624/625 series is
adequate in non -WS waters because the potential danger of chlorinated phenol formation in water
treatment facilities does not exist. Separate semi-annual monitoring will be required for
chlorinated phenols (not included as part of the 624/625 series) only in water supply classified
waters because, although there is limited data on this set of compounds, it is known that they can
be a problem in water treatment facilities.

April 8, 1996
Page 2
takes for rtmol.I. 1n ; : t nn r reaches to its outlet, and the region's drainage
area.
For oil ttr "; �,oi s that serve to collect runoff, item no. 2 listed
above 1:;cd Jbecause the calculations will determine the
t
flow to h!.: �, .Morn tl e pond.
B. Acute
Monitor all n,w!I\1 i:
showed l ­lo
Moni!or;, {
anua!
Prod t,ic
may I,., „
surface
test is
events.
minnow,;
1) Fay:
2) Fay':
perm i,
3) Far.
all I'i
Faci!it;�.,;
du -in _ ;l
fort]�c.
faci]iti,•s !i
stat , c
tox is
req k; i ,-
toxic:
C. Tot,
moll; 1nr r ,..
Dai!y ;
Hist , : '' •. '
faci!i:
exc�._
sul...
D. O>
MO!,t,:
Monit ,.
from t'
promelas) 24 -hr, Episodic
storm events have already been monitored and
<i r,rin, shOld occur during one of the two semi-
!: item E below).
tierof different chemicals (some of which
i� toxic chemicals are not discharged to
c.. A_n acute, rather than chronic, toxicity
.,,c,s are typically short-term, episodic
I at � t % waste concentration using fathead
n tcr discharges.
?A.�'i�-Io criteria will not qualify for annual
t x i c i ty during five storm events:
u ring a storm event, or
u r or fewer storm events during the last
r c� five storm events, but did not pass
, one or more of the five storm events or
conduct quarterly monitoring for the
-.dj approval for reduced monitoring. For
for the first five discrete storm events, a
a i limits should the toxicity test indicate
w ;, a al monitoring for toxicity would be
,o sampling requirements with no acute
in stormwater discharges at oil terminal
r dischargers indicated only one event in
ould TSS monitoring data indicate any
force the instream standard for turbidity.
s:i mn]e for oil and grease should be skimmed
I�

April 8, 1996
Page 6
B. Benzene
Monitor monthly
Daily maximum limit - 1.19 ug/1 * dilution of the receiving stream under average flow conditions
Benzene is a known carcinogen and can pose a potential health risk to humans consuming
water with benzene. The water quality standard for benzene in waters classified as water
supplies is 1.19 ug/l. If there is an adequate amount of past data, a reasonable potential
analysis should be conducted. If there is reasonable potential for a water quality standard
violation, the daily maximum limit given should be 1.19 ug/l multiplied by the dilution of the
receiving stream under average flow conditions (rounded to two significant digits). If there is
no reasonable potential, there will only be a monthly monitoring requirement.
Monthly monitoring for benzene is in addition to the 624/625 series semi-annual monitoring
(which includes benzene) but is only required in water supply classified waters. In non -
water supply classified waters, only the 624/625 series semi-annual monitoring is required.
REFERENCES
Dodson, Roy D., January 1996. Computing Peak Flow: Which Method Is Most Rational?. Civil
Engineering News.
Linville, Ron, (Winston-Salem Regional Office) March 1996. Telephone conversation with P.
Clark.
USEPA. March 1991. Technical Support Document For Water Quality -Based Toxics Control.
EPA/505/2-90-001.

- DRAFT -
Permit RPquirr nients for Stormw
(11�it r*: Stora
Background/ Introduction
r Discharges from
Facilities
The Permits and Engineering ?Jnit reviewed NODES permit monitoring requirements for stormwater
discharges at oil terminal f tcilit.ics docat: ci in the Greensborpp and Charlotte areas. This review revealed
inconsistencies in monitoring rca,tircm nts. These inconsistencies were discussed with staff of the
Winston-Salem and Mootesvillc rc`,;on;d offices. These discussions and a review of past information
collected at these facilities fornn cite hasis l'or the standardi monitoring requirements contained in this
Standard Operating Proccdtu-c (S )P) for Stur-Inwater Discharges from Oil Terminal Facilities. Examples
of effluent monitoring sheets ttrc. niclud(:rl at the cnd of this SOP. One sample effluent sheet is for oil
terminal facilities thaters, while the second effluent sheet is for
facilities that discharge to nota -I," waterst
Review of oil terra i n r 1 t': c i 1 i t y p e rrn i t s a I ,;o indica ted that wastewater sources were not always identified,
I
thus, the State will rc�_it,cst th tt. i1; c,il facilities characterize their wastewater sources.
Specifically, the Si:tc \,'i: i , , n . '. c. ;n< the oil terminal and identifying wastewater sources
for each region w i ! f} I,-, , ; c k),:
P i s c f l i n esti on will also specify different wastewater
treatment methods frr •1'1' `.� -- .'M1* . �s (i! appr1 priate). This information request will be
included in the co\rcr'c i :.t ft ;,_ rt pit. Li is the intent that information gathered may
be incorporated into
I. Minimum :. "°,: _:_ .-alfacilities
A. Flow
Measurement: of 11.�-�r� ;i h- ± v -s,,,, !!t;ive of a discharge event. Many oil terminal facilities
have storn'l_ �discharges may not always occur during
storm o I' thie following methods:
1) Measure_,
2) C L,1 (_­
rainf.ii.
3) Estim:,t.:
4) Banc
The rationni cgii:-1il:il: _
to (lie
or
1:11crVB
tfall, the built -upon area, and the total
during the entire discharge event, or
.< — )i• U.S. standard units (usually ignored because it
., -.
C= c! ; - " . . , ;! Cor the w a I rshed, loosely defined as the ratio of
l ; �',i,•nsity-duration-frequency curves for the specified
c' t;ration te, (in/h or mmlh)
. � � i 11 n i lig of rainfall excess when all
utm g simultaneously to flow at the outlet
is used to c:J::1. 1-,.1, I",I"o on given the runoff coefficient which accounts for
infiltrati. n : en, the.,rainfall intensity to the region, the time it