DWQ-2024-005759

Official Draft Public Notice Version Month Day, year
The findings, determinations, and assertions contained in this document are not final and subject to change following the public comment period.
FACT SHEET AND STATEMENT OF BASIS
PACIFICORP DEER CREEK MINE
UTAH POLLUTANT DISCHARGE ELIMINATION SYSTEM (UPDES)
RENEWAL DISCHARGE PERMIT
UPDES PERMIT NUMBER: UT0023604
MINORINDUSTRIAL FACILITY
FACILITY CONTACTSName:James Owen, Official Permit SignatoryPosition:VP – Environmental, Fuels & MiningName:Peter BrintonPosition:Senior Reclamation EngineerPhone Number:(801)-220-2737Permittee
Name:PacifiCorpFacility Name:Deer Creek MineMailing Address:PacifiCorp Environmental Remediation & Reclamation1407 W. North Temple, Suite 110Salt Lake City, Utah 84116Facility Location:~
8 miles Northwest of Huntington, Utah on State Highway 31
DESCRIPTION OF FACILITY
The PacifiCorp Deer Creek Mine (mine) is a former underground coal mine with standard industrial classification code 1222 for bituminous coal underground mininglocated approximately
8 miles northwest of Huntington, Utah in Emery County, and which ceased operations in January 2015. The mine portals have since been sealed and there has been no mining activity since
that time other than reclamation of the former mining areas in both Deer Creek and Rilda Canyons. Final reclamation activities were completed in November 2019 leaving the two remaining
permitted discharge pointsin place to account for any mine water discharges that may flow out of the former mine portals. This renewal permit will once again authorize any discharge
of mine water from the Deer Creek mine portal pipeline to Deer Creek (Outfall 002) and from the Rilda Canyon mine portal pipeline to Huntington Creek (Outfall 003) during the next five
years as appropriate.
SUMMARY OF CHANGES FROM PREVIOUS PERMIT
There are a few proposed changes with this renewal permit. First, the effluent flow limitation for Outfall 002 has been reduced from 5.0 million gallons per day (MGD) to 0.5 MGD as a
result of updating the actual design capacity of the newer discharge pipe as opposed to the previously calculated maximum pumping rate of the mine water during active dewatering operations.

Second, the Total Iron and Dissolved Oxygen effluent limitations for both outfalls have been updated to reflect the current Wasteload Analysis (WLA) as described further in the BASIS
FOR EFFLUENT LIMITATIONS section of this Fact Sheet.
The last permit change is the additional field monitoring for effluent temperature to be conducted and reported monthly along with the existing monitoring requirements for both Outfalls.
Temperature monitoring is now being included to provide additional water quality data in support of any future Total Maximum Daily Load (TMDL) study to address the impairment for the
receiving waters within the watershed. See the TOTAL MAXIMUM DAILY LOAD REQUIREMENTS section of this Fact Sheet for more information.
All other permit conditions remain unchanged.
DISCHARGE INFORMATION
DESCRIPTION OF DISCHARGE
The mine has been reporting self-monitoring results on Discharge Monitoring Reports (DMRs) through NetDMR on a monthly basis as appropriate. There have been no discharges from Outfall
002 since 2015 and no discharges to date from Outfall 003 since installation in late 2017. The permitted outfalls are as follows:OutfallDescription of Discharge Point
002Located at latitude 39 21' 27" North and longitude 111 06' 58" West. Mine water discharge pipe to Deer Creek.
003Located at latitude 39 23' 23" North and longitude 111 05' 23" West. Mine water discharge pipe to Huntington Creek.
RECEIVING WATERS AND STREAM CLASSIFICATION
Any discharges from Outfall 002 would bedirectly into Deer Creek, which then flows into Huntington Creek. Any discharges from Outfall 003 would be directly to Huntington Creek, which
is classified as follows according to Utah Administrative Code (UAC) R317-2-13:
Class 1C -- Protected for domestic purposes with prior treatment by treatment processes as required by the Utah Division of Drinking Water
Class 2B -- Protected for infrequent primary contact recreation. Also protected for secondary contact recreation where there is a low likelihood of ingestion of water or a low degree
of bodily contact with the water. Examples include, but are not limited to, wading, hunting, and fishing.
Class 3A -- Protected for cold water species of game fish and other cold-water aquatic life, including the necessary aquatic organisms in their food chain.
Class 4 -- Protected for agricultural uses including irrigation of crops and stock watering.
Geographical Boundary -- All waters below approximately 4,208-foot elevation to the current lake elevation of the open water of the Great Salt Lake receiving their source water from
naturally occurring springs and streams, impounded wetlands, or facilities requiring a UPDES permit. The geographical areas of these transitional waters change corresponding to the fluctuation
of open water elevation.
Beneficial Uses -- Protected for infrequent primary and secondary contact recreation, waterfowl, shore birds and other water-oriented wildlife including their necessary food chain.
TOTAL MAXIMUM DAILY LOAD REQUIREMENTS
A TMDL study was completed in August 2004 as part of the West Colorado River Watershed evaluation efforts and according to DWQ’s 2024Integrated Report and 303(d) Water Quality Assessment,
the assessment unit for this section of Huntington Creek, which is Huntington Creek and tributaries from Highway 10 crossing to USFS boundary and to headwaters, is listed as impaired
for pH, dissolved oxygen, temperature and total dissolved solids (TDS). This permit renewal will once again address each of these impairments by including the applicable effluent limitations
for pH, dissolved oxygen and TDS.
Temperature was previously evaluated through the Reasonable Potential (RP) analysis process and determined that a limit was not required for this parameter however, temperature monitoring
will be included in the permit to support any future TMDL efforts. Also according to DWQ's 2024Integrated Report and 303(d) Water Quality Assessment, the assessment unit for the section
of Huntington Creek immediately downstream, which is Huntington Creek from the confluence with Cottonwood Creek to Highway 10 crossing, is also listed as impaired for selenium.This additional
parameter of concern has been addressed through the RP process as well and previously determined that a limitation on selenium was not required however, monitoring for selenium will
be required once again as appropriate. The RP analysis is discussed further in the Reasonable Potential Analysis section of the Fact Sheet.
BASIS FOR EFFLUENT LIMITATIONS
In accordance with regulations promulgated in the Code of Federal Regulations (CFR), 40 CFR Part 122.44 and in Utah Administrative Code (UAC) R317-8-4.2, effluent limitations are typically
derived from technology-based effluent limitations guidelines, Utah Secondary Treatment Standards (UAC R317-1-3.2), or Utah Water Quality Standards (UAC R317-2). In cases where multiple
limits have been developed, those that are more stringent shall apply. In cases where no limits are applicable, Best Professional Judgment (BPJ) is utilized and refers to a discretionary,

best professional decision made by the permitting authority based upon precedent, prevailing regulatory standards, or other relevant information as appropriate.
Permit limits can also be derived from a WLAas is the case with the Dissolved Oxygen minimum concentrations, as well as the Total Iron effluent limitations. The WLA incorporates Secondary
Treatment Standards, Water Quality Standards, including TMDL impairments as appropriate, Antidegradation Reviews and designated uses into a water quality model that projects the effects
of discharge concentrations on receiving water quality. Effluent limitations are those that the model demonstrates are sufficient to meet State water quality standards in the receiving
waters. During this UPDES renewal permit development, a WLA and ADR were performed. An ADR Level I review was performed and concluded that an ADR Level II review was not required this
time since this is a simple permit renewal with no proposed increases in flow or concentrations from the previous permit. The WLA indicates that the effluent limitations will be sufficiently
protective of water quality, in order to meet State water quality standards in the receiving waters. The WLA and ADR information has been included as an attachment to this Fact Sheet.
Limitations on pH are based on Utah Water Quality Standards. Limitations on total suspended solids (TSS) were previously based on Utah Secondary Treatment Standards as found in UAC
R317-1-3.2and remain unchanged once again for both Outfalls. Regarding Outfall 002, TSS limitations are carried over from the previous permit requirements based upon a Level II ADR
that was completed by the mine and approved by DWQ in 2013. Although a Level II ADR is not required for this permit renewal, the more stringent TSS limitations as a result of the previous
ADR will apply once again to avoid Anti-backsliding as per U.S. EPA policy.
The total iron limitations for both outfalls remain the same as in the previous permit. For Outfall 002 it is based upon the State Water Quality Standard of 1.0 mg/L for dissolved iron
(UAC R317-2 Table 2.14.2) and will once again be included in this renewal permit as 1.0 mg/L for total iron. Total iron includes the dissolved iron component and is therefore considered
a more protective permit provision. Although the WLA indicates a higher total iron limitation of 7 mg/L may be allowed for Outfall 002, the more stringent limitation as a result of
the previous permit will apply once again to avoid Anti-backsliding as per U.S. EPA policy. Previous discharge data indicates that the mine should be able to continue complying with
the more stringent limitation. The iron limitation for Outfall 003 remains in place from the previous permit as well and is derived from both the WLA and from 40 CFR 434 Subpart E,
Post-Mining Areas and Alkaline Mine Drainage. The limitations are 7.0 mg/L as a daily maximum and 3.5 mg/L for a monthly average for total iron as appropriate. The oil and grease limitation
is based on BPJ of the permitting authority and is consistent with other industrial facilities statewide.
Total dissolved solids (TDS) limitations are based upon the state water quality standard for concentration at 1200 mg/L, as found in UAC R317-2-14 Table 2.14.1, and the Colorado River
Basin Salinity Control Forum (CRBSCF) for mass loading as authorized in UAC R317-2-4. Regarding TDS loading, the CRBSCF Policy entitled “NPDES Permit Program Policy for Implementation
of Colorado River Salinity Standards” (Policy), with the most current version dated October 2017, requires the TDS loading limitation of one-ton per day (or 366 tons per year) as a sum
from all discharge points, unless the average concentration of TDS is 500 mg/L or less. If the concentration of TDS at any Outfall is less than or equal to 500 mg/L as a thirty-day
average, then no loading limit applies for that Outfall. The one-ton per day (or 366 tons per year) loading limit applies only to those Outfalls exceeding 500 mg/L as a thirty-day average.
Those Outfalls exceeding 500 mg/L as a thirty-day average, collectively, need to meet the one-ton per day (or 366 tons per year) limit. If one-ton per day (or 366 tons per year) TDS
cannot be achieved, then the permittee will be required to remove salinity/TDS in excess of one-ton per day (or 366 tons per year) by developing a treatment process, participating in
a salinity off-set program, or developing some type of mechanism to remove the salinity/TDS. The selection of a salinity control program must be approved by the Director of the Division
of Water Quality (DWQ). In April 2018, DWQ approved the mine’s salinity control program plan as submitted to account for any future TDS credit tons if needed as appropriate.
The flow limitations are based upon the maximum design flow of each Outfall as previously provided by the mine.
Reasonable Potential Analysis
Since January 1, 2016, DWQ has conducted reasonable potential analysis (RP) on all new and renewal applications received after that date. RP for this permit renewal was conducted following
DWQ’s September 10, 2015 Reasonable Potential Analysis Guidance (RP Guidance).There are four outcomes defined in the RP Guidance: Outcome A, B, C, or D. These Outcomes provide a frame
work for what routine monitoring or effluent limitations are required
A qualitative RP analysis was performed previously on the applicable metals constituents from mine water data as previously discharged through Outfall 002. Initial screening for metals
values that were submitted previously through both the DMRs and permit renewal application information showed that a closer look at any of the metals is not needed since all of the metals,
excepting for total iron which already has specific effluent limitations as otherwise derived, were either below the appropriate method detection limits and/or below the applicable water
quality standards, or simply believed to be absent based upon historical use and existing data. Therefore, no RP currently exists, except for total iron, and a more quantitative RP
analysis was not necessary at this time for Outfall 002. Regarding Outfall 003, since there have not been any discharges to evaluate, the provisions to monitor for metals as derived
from the previous RP analysis will remain in the permit for any future discharges and subsequent RP analysis as appropriate. The results of the RP analysis was; Outcome C: No new effluent
limitation. Routine monitoring requirements maintained as they are in the permit.A copy of the RP analysis is included at the end of this Fact Sheet.
The permittee is expected to be able to continue complying with the effluent limitations as follows:<INSERT TABLES from Permit>SELF-MONITORING AND REPORTING REQUIREMENTSThe following
self-monitoring requirements are the same as in the previous permit with the addition of temperature monitoring as mentioned previously. Sampling frequency is based on the mine being
a minor industrial permit with a maximum design effluent flow of <1 MGD for each Outfall and is consistent with other similar coal mine UPDES permits. The permit will once again require
reports to be submitted monthly on DMR forms via NetDMR due 28 days after the end of the monitoring period. Effective January 1, 2017, monitoring results must be submitted using NetDMR
unless the permittee has successfully petitioned for an exception. <INSERT TABLES from Permit>
BIOSOLIDS
The State of Utah has adopted the 40 CFR 503 federal regulations for the disposal of sewage sludge (biosolids) by reference.However, this facility does not receive, generate, treat or
dispose of biosolids. Therefore 40 CFR 503 does not apply and biosolids provisions are not being include in the permit as appropriate.
STORM WATER
Separate storm water permits may be required based on the types of activities occurring on site.Permit coverage under the Multi Sector General Permit (MSGP) for Storm Water Discharges
from Industrial Activities is not required based on the lack of industrial activities occurringat the reclaimed mine locationsand since the potential to discharge industrial storm water
has been obviated upon final reclamation of the former mine site as completed by November 2019. All former mine related equipment, facilities and storage areas have been removed and
the disturbed areas have been restored to a natural topography as part of the final reclamation activity.
Permit coverage under the Construction General Storm Water Permit (CGP) is required however, for any construction at the facility which disturban acre or more, or is part of a common
plan of development or sale thatis an acre or greater and which is not part of any active mining activities. A Notice of Intent (NOI) is required to obtain a construction storm water
permit prior to the period of construction.Information onstorm water permit requirements can be found at http://stormwater.utah.gov
PRETREATMENT REQUIREMENTS
This permittee does not discharge process wastewater to a sanitary sewer system. Any process wastewater that the facility may discharge to the sanitary sewer, either as a direct discharge
or as a hauled waste, is subject to federal, state, and local pretreatment regulations. Pursuant to section 307 of the Clean Water Act, the permittee shall comply with all applicable
federal general pretreatment regulations promulgated, found in 40 CFR 403, the state’s pretreatment requirements found in UAC R317-8-8, and any specific local discharge limitations developed
by the Publicly Owned Treatment Works (POTW) accepting the waste.

In addition, in accordance with 40 CFR 403.12(p)(1), the permittee must notify the POTW, the EPA Regional Waste Management Director, and the State hazardous waste authorities, in writing,
if they discharge any substance into a POTW which if otherwise disposed of would be considered a hazardous waste under 40 CFR 261. This notification must include the name of the hazardous
waste, the EPA hazardous waste number, and the type of discharge (continuous or batch).
BIOMONITORING REQUIREMENTS
A nationwide effort to control toxic discharges where effluent toxicity is an existing or potential concern is regulated in accordance with the Utah Pollutant Discharge Elimination System
Permit and Enforcement Guidance Document for Whole Effluent Toxicity Control (biomonitoring), dated February 2018. Authority to require effluent biomonitoring is provided in Permit
Conditions, UAC R317-8-4.2, Permit Provisions, UAC R317-8-5.3 and Water Quality Standards, UAC R317-2-5 and R317 -2-7.2.
The permittee is categorized as a minor industrial facility that rarely discharges since the mine closure in 2015, in which toxicity has been neither an existing concern, nor likely
to be present based on past monitoring data from Outfall 002, including successfully passing previous WET tests. Based on these considerations, there is no reasonable potential for toxicity
in the permittee’s discharge (per State of Utah Permitting and Enforcement Guidance Document for WET Control). As such, there will be no numerical WET limitations or WET monitoring requirements
in this permit, but the permit will contain a toxicity limitation re-opener provision that allows for modification of the permit should conditions change in the future.
Additionally, and since there has not been a discharge to date from Outfall 003, the permitee will still be required to sample for and submit to DWQ results for at least one acute WET
test of discharge water from Outfall 003 (utilizing full dilution and both test species). The sample, which can be either a grab or composite sample, shall be collected prior to discharge
into Huntington Creek and obtained within 30 days upon initially discharging via Outfall 003. The permit may then be re-opened and modified based on the results of the future WET testing,
following the aforementioned toxicity limitation re-opener provision, that allows for modification of the permit at any time in the future should additional information indicate the
presence of toxicity in the discharge. These provisions remain in place from the current permit and are consistent with other similar permits in Utah based upon BPJ of the permitting
authority.
PERMIT DURATIONIt is recommended that this permit be effective for a duration of five (5) years.Drafted and Reviewed byJeff Studenka, Discharge Permit WriterDaniel Griffin, BiosolidsJennifer
Robinson, PretreatmentLonnie Shull, BiomonitoringJordan Bryant, Storm WaterAmy Dickey, TMDL/Watershed Suzan Tahir, Wasteload Analysis/ADRUtah Division of Water Quality, [phone]PUBLIC
NOTICE INFORMATION (to be updated after)Began: Month Day, YearEnded: Month Day, YearComments will be received at: 195 North 1950 West PO Box 144870 Salt Lake City, UT 84114-4870The Public
Notice of the draft permit was published on DWQ’s website for at least 30 days as required.During the public comment period provided under R317-8-6.5, any interested person may submit
written comments on the draft permit and may request a public hearing, if no hearing has already been scheduled. A request for a public hearing shall be in writing and shall state the
nature of the issues proposed to be raised in the hearing. All comments will be considered in making the final decision and shall be answered as provided in R317-8-6.12.ADDENDUM TO FSSOBDuring
finalization of the Permit certain dates, spelling edits and minor language corrections were completed. Due to the nature of these changes they were not considered Major and the permit
is not required to be re Public Noticed.Responsiveness Summary(Explain any comments received and response sent. Actual letters can be referenced, but not required to be included).
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ATTACHMENT 1
Wasteload Analysis Information
Outfall 002 (DWQ-2024-004814 & DWQ-2024-004815)
Outfall 003 (DWQ-2024-004819 & DWQ-2024-004821)
This Page Intentionally Left Blank
ATTACHMENT 2
Reasonable Potential Analysis
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REASONABLE POTENTIAL ANALYSIS
Water Quality has worked to improve our reasonable potential analysis (RP) for the inclusion of limits for parameters in the permit by using an EPA provided model. As a result of the
model, more parameters may be included in the renewal permit. A Copy of the Reasonable Potential Analysis Guidance (RP Guide) is available at water Quality. There are four outcomes
for the RP Analysis. They are;
Outcome A:A new effluent limitation will be placed in the permit.
Outcome B:No new effluent limitation. Routine monitoring requirements will be placed or increased from what they are in the permit,
Outcome C:No new effluent limitation. Routine monitoring requirements maintained as they are in the permit,
Outcome D:No limitation or routine monitoring requirements are in the permit.
2019 Summary Results of Reasonable Potential Analysis for Deer Creek Mine (UT0023604)
Parameter
No. of Samples
MEC*
mg/L
Water Quality Standards MAC**
Outcome/Result
WLA mg/L
Acute mg/L
Chronic mg/L
Total Arsenic
14
0.005
0.05
0.05
0.05
MEC < MAC***
Total Cadmium

15
<0.001
0.006
0.0068
0.006
MEC < MAC***
Total Chromium
3
<0.005
0.011
0.016
0.011
MEC < MAC***
Total Copper
7
<0.02
0.0248
0.0411
0.0248
MEC < MAC***
Total Lead
15
<0.01
0.0137
0.1
0.0137
MEC < MAC***
Total Mercury
3
<0.0002
0.00012
0.0014
0.00012
MEC < MAC***
Total Nickel
3
0.037
0.137
0.6101
0.137
MEC < MAC***
Total Selenium
14
<0.0035
0.0046
0.02
0.0046
MEC < MAC***
Total Silver
4
<0.002
0.0271
0.0271
NA
MEC < MAC***
Total Zinc
16
0.07
0.3159
0.3159

0.3159
MEC < MAC***
Total Aluminum
6
0.5
0.75
0.75
NA
MEC < MAC***
Total Boron
10
0.021
0.75
0.75
NA
MEC < MAC***
Total Iron
>100
7.53
7.0721
7.0
3.5/1.0
MEC > MAC = RP
Temperature ℃
>100
16.3
24.7
35.7 (max)
24.7 (min)
MEC < MAC***
NA = not applicable
*MEC – Maximum expected effluent concentration as determined from existing data set and Reasonable Potential analysis.
**MAC – Maximum allowable concentration from Water Quality Standards and/or Wasteload Analysis.
***MEC less than MAC. No Acute or Chronic limit required.
Based upon the policy “Reasonable Potential Analysis Guidance” developed by the Utah Division of Water Quality on September 10, 2015 and subsequently implemented beginning January 1,
2016 for all new and renewal permits; it was determined not to include any new total metal effluent limits in the 2019 renewal permit. This is because all the data points reviewed were
below the applicable Water Standards and/or method detection limits, excepting for total iron which already has specific effluent limitations as derived from previous permit development
and the 2017 RP analysis (see table above). Therefore, no RP currently exists at the mine for metals except total iron and a more quantitative RP analysis was not necessary at this
time. Monitoring for the remaining metals will remain in place however, as detailed in the permit. This will be re-evaluated during the next permit cycle as appropriate.
The results of the RP analysis was; Outcome C: No new effluent limitation. Routine monitoring requirements maintained as they are in the permit.