HomeMy WebLinkAbout2.0 Staff Report 12.17.07REQUEST:
APPLICANT:
LOCATION:
BOCC 1211712007
CR
PROJECT INFORMATION AND STAFF COMMENTS
Site Approval for Expansion of an Existing
Wastewater Treatment FacilitY
Roaring Fork Water and Sanitation District
South of the City of Glenwood Springs, CO
I. SUMMARY OR REQUEST
Roaring Fork Water and Sanitation District (RFWSD) was created rn 1994 to provide water and
sanitation services to Aspen Glen Planned Unit Development and surrounding developments. The
existing facility currently treats 0.107 million gallons per day (MGD). The Waste Water Treatment
Facility was master planned to be constructed in three phases of 0. 107 MGD with a maximum build
out of 0.321MGD.
Due to the growth RFWSD is experiencing the District has decided to build the last two (2) phases
concurrently. This is consistent with the service plan approved by Garfield County. The current
facility is experiencing flows at approximately 557o of capacity and is meeting the required discharge
limits.
a. Service area and Population
The District's service area includes Aspen Glen, Coryell Ranch, Midland Point and konBridge'
Projected service area includes the area on the east side of the Roaring Fork River from the north one
the east side of Highway 82 at the Colorado Mountain College intersection to the south on the east
side of Highway 82 at the Cattle Creek Intersection.
b. Description of Selected Alternative
Roaring Fork Water and Sanitation District is the Regional Wastewater Treatment Facility,
consolidation was not considered.
III. RELATIONSHIP TO THE COMPREHENSIVE PLAN
The existing facility is located in Study Area I of the Garfield County Comprehensive Plan of 2000.
The Plan's Proposed Land Use Districts map designates the service area as Residential High and
Medium Density. The proposed expansion does not conflict with Garfield County's Comprehensive
Plan.
IIL ISSUES AND CONCERNS
B. Role of the Board of County Commissioners
State Statutes: C.R.S .25-S-io2(2)(a-c), and the "Regulations for Site Applications for Domestic
Wastewater Treatment Works", defines the parameters by which the Water Quality Control Division
(..Division") shall review and approve or deny a site application for a wastewater treatment works.
The Division is required to determine that each site location is 1) consistent with the long range,
comprehensive planning for the area in which it is to be located; 2) thatthe plant on the proposed site
will be managed to minimize the potential adverse impacts on water quality; and 3) must encourage
the consolidation of wastewatel treatment works whenever feasible.
The Applicant is required to obtain a recommendation of approval, denial or no comment from the
Garfield County Board of Health and County Board of County Commissioners and various other
local and regional agencies.
Therefore, Garfield County's involvement in the process is to determine whether or not the proposed
wastewater treatment work is consistent with "the long-range comprehensive planfor the area as it
affects water quatity and any approved regional wastewater management plan for the area".
V. RECOMMENDATION
Staff recommends that the Garfield County Commissioners recommend APPROVAL of the site
application for the expansion of the Roaring Fork Water and Sanitation Districts Wastewater
Treatment Facility.
SCHMUESER i GORDON MIYER
5NG]N5EF= '
5Li FVEYOFS-i
October 18,20OT
Fred Jarman
Garfield County Planner
108 8th Street
Suite 201
Glenwood Springs, CO 81601
GLETJV/OO" SPRING=
I 18 w. 6TH, sulrE 2OO
crrNwooD sFRNGs, co I I 60 I
97G945- I OO4
ry: 970-945-59.48
,?-===-r Louis O. Meyer, P.E.
Project Engineer
c-flfsrfu-r au[f
P.o. Box 3088
cREsrED B]fre, co al?24
97G349-5355
ry: 970-349-5358
ASPEN
P.O.BOx2l55
asPEN,coBl6l2
970.925-6727
s,97.f,-925-4157
RE: RFWSD - Site Apptication for an expansion of an existing domestic wastewater
treatment works
Dear Mr. Jarman:
Enclosed you willfind four copies of CDPHE Regulation 22 (Site Application) submitted on
behalf of tlre Roaring Fork Water and Sanitation District (Distric$ for a proposed expansion to
the existing wastewiter treatment facility. The prwiously approved site application is number
4133 and the discharge permit is CDS permit number CO-O0M750. Garfield County is required
to review and comment on this application. One copy is for you to keep and I will pickup the
other three copies when they are signed.
By way of history, the RFWSD was created in 1994 as the regionalwater and wastewater
piovidlr to serve the Aspen Glen P.U.D. and the surrounding developments. The District has
an approved service plan on file with the County. The existing ! AIVTF is a 0.107 million gallons
p"1. d"y (MGD) activated sludge facility with tertiary filtration followed by discharge to a natural
welani.'fne tnpff was maiter planned to be built in three phases of 0.107 MGD, to a build
out of 0.321 MGD.
The District has been experiencing growth consistent with the service plan approved by Garfield
County and with the P.U.D.s approved by Garfield County in this area. The District has
decided, because of the growth and the increase in construction costs, to build the last two
phases of the 1t\fl/VTF as one phase. The District is planning on having the new expansion
under construction by the fall of 2008.
Thank you in advance for your time and if you have any questions or if you would like an
electronic copy of this report in PDF format, please call or e.mail: chrisl@sgm-inc.com'
Sincerely,
SCHMUESER GORDON MEYER, INC.
-t'-ry/"Y
Chris Lehrman, E.l.
Design Engineer
Enclosures: ( ) RFWSD Regulation 22
Cc: RFWSD Statf
OCiI$ZAi)l
l:\.1996\96059\4-82 \ A /TF Expansion Planning\2 - ! A /TF Expansion Permitting\L 20071018 Fred Jarman.doc
Engineering Report Executive Summary
The Roaring Fork Water and Sanitation District is submitting this application to allow for the
construction of an expansion to the existing wastewater treatment facility. This report
follows the outline and guidelines of the "Regulation No. 22" guidance document (Site
Application). This executive summary will provide a brief description of the key points
the document.
The District currently owns and operates a 0.107 million gallons per day (MGD)
activated sludge facility with terliary filtration. The facility was designed in 1994 and
was planned to have three phases totaling 0.321 MGD at build out' Currently, the
WWTF is experiencing flows in the range of 55o/o of capacity and is meeting the
discharge limits. The District does not have an inflow or infiltration problem.
The District has been experiencing an accelerated growth rate due to the shortage of
housing and housing developments trying to satisfy that demand in the region. ln
2OO7 ,the District experience d a l5o/o per year growth rate. The growth rate is
projected to continue at the same rate or higher for the next several years'
3. The construction costs in the region have also have had an accelerated gowth of
upwards of 25r/o per year. The growth has been attributed to the high cost of living,
libor shortage, and the abundance of construction projects in the region.
4. The District has decided to build the WWTF to the full build out of 0.321 MGD
because of both the growth rate of the District and the increased construction costs'
The Board of Directors feels like the accelerated growth rate will continue and
construction costs will only go up, so it would be prudent to build the rest of the
planned wwTF while the District is in a very good financial situation.
I:\1996\96059\4-82 WWTF Expansion Planning\2 - WWTF Expansion Permitting\Reg 22Final'doc
Page 2 of 12
in
1.
2.
22.5(2) Eng ineering RePort
22. 5(2) (a) Service Area
The current service area for the District includes the developments of Aspen Glen, Coryell
Ranch, Midland Point, and IronBridge, all of which are located along Garfield County Road
109 and the Roaring Fork River. The projected service area will consist of the current
service area plus the area on the east side of the Roaring Fork River expanding from the
north on the east side of HWY 82 at the CMC intersection to the south on the east side of
HWY 82 at the Cattle Creek Intersection. Presently, this area is being served by ISDS
systems and small package plants. The District's service area is shown in the attached map
labeled figure 1.
The current population of the District is roughly 440 house hold equivalents (EQRs) with
flows to the WWTF at roughly 59,000 gallons per day (GPD). The flows to the WWTF have
been much lower than industry standards with around 130 gallons per EQR per day. The
traditional industry standards are 350 gallons per EQR per day. The low flows can be
explained by the high amount of second home ownership in the District and also by the high
number of homes that are under construction and are not being lived in. in the projections
that have been done for the District, these historical low flows were accounted for so that the
WWTF was not over designed. Trends will change to much higher flows. The higher flows
can be explained by more first home owners living and working in the region and the
construction of the homes being completed with people moving into them. A population and
loading projection study is attached as figure 2.
The growth in the district can be explained because the existing developments are roughly
30% built and they are seeing rapid growth due to the real estate values in the county. In
2OO7,the District has seen a 75o/o per year growth rate and it has been forecasted to have as
much growth or more in 2008. The District is also receiving preliminary requests for water
and waste water service from areas in the projected service areathat are not currently being
served. In the past, these developments have not been able consolidate with the District
because of the high cost of installing infrastructure to the District's facilities. In the future,
the District is anticipating several new developments that will have the capital to extend the
required infrastructure which will enable these smaller developments to connect. When the
new developments are approved and begin building homes, it will accelerate the growth rate
even more. On top of that, once the infrastructure is installed to their properly lines, the
District anticipates that several of the smaller developments will connect at that time.
I:\1996\96059\4-82 WWTF Expansron Planning\2 - WWTF Expansion Pernrrtting\Reg 22 Frnal.doc
Page 4 of 12
S]A|E OF COLOIUDO
Bill Ritter, Jr., Governor
James B. Martin, Executive Director
Dedicated to protecting and improving the healih and environmenl ol the people oi Colorado
4300 Cherry Creek Dr- S. Laboratory Services Division
Denver, Colorado 80246-1530 8100 Lowry Blvd.
Phone (303) 692-2000 Denver, Colorado 80230-6928
TDD Line (303) 691-7700 , (303) 692-3090
Located in Glendale, colorado
hnp://www.cdphe.slate.co. us
Colorado Departrnert
of Publc Health
and Envkonment
Iuly 12,2007
Christine A. Bechtel, EI
Schmueser Gordon Meyer
118 W. Sixth Street, Suite 200
Glenwood Springs, CO 81601
Re: PEL-200229, Roaring Fork Water and Sanitation District WWTF
Dear Ms. Bechtel:
The Water Quality Control Division (Division) of the Colorado Department of Public Health and
Environment has prepared, per your request, the Preliminary Effluent Limits (PELs) for the
rehabilitation and expansion of the Roaring Fork Water and Sanitation District wastewater
treatment facility (WWTF). These effluent limits were developed, as detailed in the attached
document, for use as one of the submittals in your application for Site Approval.
pELs developed for the WWTF (Tables 1 and2) are based on effluent limits for pollutants of
concem as established in the Regulations for Effluent Limitations (Regulation No. 62), and water
quality-based effluent limits (see the analysis in the attached document) necessary for protection
of the water quality in the receiving water. With a hydraulic design capacity of 0.32imillion
gallons per day (MGD) and discharge either to wetlands or to the Roaring Fork River, both of
which are identified as stream segment COUCM03a, the Roaring Fork W&SD WWTF may
require an indjvidual permit, depending on the discharge location.
The total ammonia limits warrant clarification. As explained in the attached document, the total
a:lmonia water quality-based effluent limits (WQBELs) are based on assumptions, given the
absence of adequate effluent and in-stream pH and temperature data. This is done per Division
standard procedure and utilizes statistically determined in-stream and effluent pH and
temperature corrditions for various types of facilities as inputs to the Ammonia Toxicity
(AMMTOX) Model.
::, :,"q0
d0)
^5
Table 1
Proposed Roaring Fork \\/&SD WWTF Expansion
Preliminary Effluent Limitq for Discharge to the Roaring Fork River
BODs (mg/l)45 (7-day average), 30 (30-day average)
BOD5 (% removal)85 (30-day average)
TSS, mechanjcal Plant (mg/l)45 (7-day average), 30 (30-day avgqgg)
TSS, mechanical Plant (% removal)85 (30-day average)
Oil and Grease (mg,4)l0 (maximum)
pH (s.u.)6. -5-9.0 (minimum-maximum)
Other,Po:llutants Mox,Cap'olr Wgm @ 100% Dilution,,t:
Fecal Coliform (#/100 rrn)1 2,000 (7-day geomean), 6,000 (30-day geomean)
E. coli (#1100 m])4,000 (7-day geomean), 2,000 (30-day geomean)
Total Residual Cilorine (mgA)0.5 (daily maximum), Report (30-day average)
Monthiy Total Ammonia, Jan. - Dec. (mg/l)Report (daily maximum), Report (30-day average)
Table 2
Prell141nqrLEflqgal Limiis for Discharge to the Tributary Wetlands
lODs (mg/l)45 (7-day average),30 (30-day average)
3OD5 (% removal)85 (30-day average)
ISS, mechanical Plant (mg/l)45 (1 -day average), 30 (30-day average)
I'SS, mechanical P1ant (% removal)85 (30-day average)
fil and Grease (mg/i)10 (maximum)
rH (s.u.)6. 5 -9. 0 ( minimum-maximum)
Other Pollutants \YQBELS
;ecal Coliform (#/100 ml)400 (7-day geomean), 200 (30-day geomean)
coli (#1100 nl)252 (7-day geomean), 126 (30-day geomean)
Iotal Res id ual ClrlPryCl-g4)0.019 (daily rnximum), 0.01 I (30-day average)
Monthly Totol4mmgnlg
ll'OBDLS ADBACS A?IS
Iamrary (-d)-19 (daily maximum), 5.6 (30-day average)3.8 (2-)r average)3.4 (30-day average
:ebruary (mg/l)19 (daily maximr.rm). -s.6 (30-day average)2.9 (2-w averase)3.4 (30-day average
t4arch (mg/l)18 (dailv maximum), -s.4 (30-dav average)3.1 (2-yr average)3.4 (30-dav average
A.oril (msll)18 (dailv maximum), 5.4 (30-day average)3.7 (2-w average)2.0 (30-dav averase
l{av (mg/l)l8 (dailv maximum), 5.-5 (3O-dav average)2.8 (2-w average)2.0 (30-dav average
Iune (mg/l)I9 (dailv maximum), 5.1 (30-dav average)1.8 (2-W averase)2.0 (3O-dav averase
Iulv (mg/l)19 (dailv maximum), 4.4 (30-day average)3.4 (2-w average)2.0 (30-dav averase
AueLrst (mPy'l)22 (dailv maximum), 4.1 (30-day average)2.5 (2-w average)2.0 (30-day average
S.rt.*U". (rn.a/l) | 20 (daily maximum). 4.6 (30-day average)3.2 tT-yr average)2.0 (30-dav average
lctober (ms;l)i9 (dailv maximum).5.0 (30-day a\/erage)3.2 {2-w a1'erage)3,4 (3O-dav average
\ovember (mdD-18 (daiiv maximum). 5.5 (30-dav average)2.3 (2-w averase)3.4 (30-dav averase)
)ecenrber (mg,'l)18 (dailv maximum). 5.4 (30-dav average)2.8 (2-w averase)3.4 (3O-dav averase
Additionally, since the recejving \\,ater is subject to antidegradation-based effluent limits, two-
vear rolling-average liniits have been cietermined for discharges to the wetlands (note that
antidegadation-based effluent limits did not apply to discharges directiy to the Roaring Fork
River); for ammonia. These are presented under ADBACs in Table 2. In effect, oniy the
assimilative capacity limits apply until sufficient effluent data (two cycles) are collected to repod
the rolling average. Thus, the facility is expected to meet the ADBACs after two years of
operation.
The proposed facility may elect, as an alternative to ADBACs, continldng with the existing
effluent mass loading to the receiving water. These limitations are called Non-Impact Limits
(NIL). The maximum pounds of ammonia in the effluent are limited to the currently limited load
based on the current concentration limit and the current design flow; or, *'here ammonia limits
have not been estabiished, the maximum historic, monthly concentration in the effluent, refened
to as the implicit limit, at the current design flow. These mass values are then translated to MLs,
by taking the mass divided by the proposed desigrr flow,
If you have any questions regarding this matter, please contact me at (303) 692-3608.
Sincerely,(',{* n //a-t-r%
Eric T. OpPelt, P.E.
CDPH&E, WQCD
Kent Kuster, WQCD - Engineering Section
Mark Kadnuck, WQCD - Engineering Section
PEL-200229 ftle
Roaring Fork \tr/SD WV/TF Preliminary Effluent Limits PEL-200229
PREIIn,ttxARy ETFLUENT Llults, Appuxux A
TIiE ROARING FORK RTVSN
RoantNc Fonx W&SD WWTF
Table A-l
Assessment SummarY
Name of FaciiitY Roarins Fork W&SD WWTF
PEL Ntimber PEL-200229
WBID - Stream
Segment
Upper Colorado River Basin, Roaring Fork River Sub-basin, Stream Segment
03a: Mainstem of the Roaring Fork River, including all tributaries and
wetlands, from a point immediately belou' the confluence with Hunter Creek,
to the confluence with the Colorado River except for those tributaries
included in Segment I and specific iistings in Segments 3b through 10.
COUCRF03a
Classifications Cold Water Aquatic Life Class 1
Class I a Existing Primary Contact Recreation
Agriculture
Water Supplv
Designation Undesi.qnated
I. Introduction
The preliminary effluent limits (PELs) evaluation for the Roaring Fork Water and Sanitation District
(W&SD) Wasrewater Treatment Faciiity (WWTF), hereafter refened to as the Roaring Fork W&SD
WWTF, was developed for the Colorado Department of Public Health and Environment (CDPHE)
Water Quality Control Division (Division). The evaluation was conducted to facilitate issuance of
PELs for the Roaring Fork W&SD WWTF for pollutants found to be of concern.
Figure A-1 contains a map of the study area evaluated as part of PELs development.
The Roaring Fork W&SD WWTF is located in Garfield County, approximately five miles north of
Carbondale, Colorado. The Roaring Fork W&SD WWTF currently discharges to wetiands that are
adjacent to the WWTF and considered to be tributary to the Roaring Fork River (and hereafter
referred to as the "Tributar),Wetlands"). In addition to a proposed expansion in hydraulic capacity,
the focility also is considering adding a discharge point directly to the Roaring Fork River. This PEL
will assess discharges to both potential receivirrg waters at the proposed hydraulic capacity of 0.321
MGD (0.50 cfs).
For discharge to the Roaring Fork River, the ratio qf the low flow of the Roaring Fork River to the
proposed Roaring Fork W&SD WWTF design flow is 2'70:1. The nearest upstream and doxmstream
facilities had no impact on the assinlilative capacities available to the Roaring Fork W&SD WWTF.
Analyses thus irrdjcate that assimilative capacities of the Roaring Fork River are very large.
PELs Appendix.A Page 1 of21 Last Revised by EO July 8, 2007
Roaring Fork WSD W\\,/TF Preliminary Effluent Limits PEL-200729
Figure A-1
Stucly Area
!+'/'
I
Lhvr slora\tatlon
5
:!
Roaring Fort wSn wwITF
l'l
g
.^ ,;:
:! ,.
- .Crvstal River
I
LEGEHD
Roaring Fork River
!"'-E
* stetB
-
co$nty
W LatelPorxd/Ocean
-
f3p7s5sffiyF Highlay
-
Cain€ctorW St;eem
Scale 1:218183
*av*r*p8--truP Ecale
g.zffi l*i I i tary Arae
Sig_i% +lat I ona I Pa,rk
WDther ?a*i--l C i tv* f,6a6[y
Source: US Census
Bureau, Tiger Map Server
f WWTF Discharge Location
* Water Quality Sampling Station
O Flow Gage Station48"i
#r*JE u,io,*,lt*'f!*ilti$
For continued discharge to the Tributary Wetlands, it is the Division's standard procedure to assume,
absent a nrixing zone study, that the iow flow of a wetland is zero. Thus, for purposes of this PELs
analysis, the low flow is assumed to be zero. The Roaring Fork WWTF is the sole known point
source contributor to this wetland. No other point sources were identified as dischargers to the
wetlands. Thus, the findings of this assessment indicate that there is no dilution, no other sources of
pollutants ofconcern, and tl,at assimilative capacities are equal to the in-stream standards applied to
the Roaring Fork WWTF efiluent discharge.
Information used in this assessment includes data gathered from the Roaring Fork W&SD WWTF,
the Division, the Colorado Division of Water Resources (DWR), the U.S. Environmental Protection
Agency (EPA), the U.S. Geological survey (USGS), the U.S. Census Bureau and communications
with the local rvater commissioner. The data used in the assessment consist ofthe best information
available at the time of preparation of this PELs analysis.
PELs Appendix A Page 2 of21 Last Revised by EO.Iuly 8, 2007
.;-\")
:j
, l'.
:'-Fci
iqgs
Roaring Fork WSD WWTF Preliminary Elfluent Limits PEL-200229
il. \\/ater Quality
The Roaring Fort W&SD WWTF discharges to the Water Body ldentification (WBID) stream
segment COUCRFO3a, u,hich means the Upper Colorado River Basin, Roaring Fork River Sub-
basin, Stleam Segment 03a. This segment is corlposed of the "Mainstem ofthe Roaring Fork River,
including all tributaries and u,etlands, fi'om a point inmrediately belou,the confluence with Hunter
Creek, to the confluence rvilh the Colorado River except for those tributaries included in Segment 1
and specific listings in Segnients 3b through 10." Stream segm,ent COUCRF03ais classified for
Cold Water Aquatic Life Class 1, Class 1a Existing Primary Coirtact Recreation, Water Supply and
Agriculture.
Statervide Basic Standards have been developed in Section 31.11(2) and (3) of The Basic Standards
and Methodologies for Surface l|'ater to protect the waters of the state flom radionuclides and
organic chemicals. In Section 31.11(1) of the regulations, narrative standards are appliedto any
pollutant of concem, even where there is no numeric standard for that pollutant. Waters of the state
shall be "free from harmful substances in harmful amounts." Total dissolved solids (TDS), and
sediment are such pollutants of concern being discussed by Agricultural and Water Quality Standards
workgroups. ln order to protect the Basjc Standards in waters of the state, effluent limitations with
monitoring, or'honitoring only''requirements for radionuclides, organics, TDS, or anyparameter of
concem could be put in CDPS discharge permits.
Numeric standards are developed on a basin-specific basis and are adopted for particular stream
segments by the Water Quality Control Conrmission. To simplify the listing of the segment-specific
standards, many of the aquatic life star-rdards are contained in a table at the beginning ofeach chapter
of the regulations. The standards in Table A-2 have been assigned to stream segment COUCMO3a
in accordance rvith the Classifications and Nunzeric Standa;'dsfor Upper Colorado River Basin and
North Platte River (Planning Region l2).
Note that the tenns of and associated values that correspond to TVS and WS are furtherexplained in
the regulations. Except for ammonia, tlrose pollutants rvith TVS-based and WS-based standards are
nol applicable to this faciiity and thereibre no further discussion is provided as part ofthis analysis;
ammonia is discussed further in Section IV of this analysis.
Ambient Vl/ater Qualitt'for the Roarinq Fork River
The Division evaluates ambient u,ater quality based on a variety of statistical methods as prescribed
in Section 31.8(2)(a)(i) and 31.8(2XbXiXB) of the Colorado Departruent of Public Health and
Enttirontnent ll/ater Qualih; Control Contmission Regulation No. 3I . Ambient water quality is
evaluated in this WQA anail,sis for use in determining assimilative capacities.
To conduct an assessnent of the arnbient rvater quality upstream of the Roaring Fork W&SD
WWTF, data were gathered from Division Station 12702 (Roaring Fork River below Confluence
with Cattle Creek). located approximately 3 miles dou'nsfream from the facility. Data were limited
to trvo data points coliected in lvlay 1 998 and February 1 999. Note that although these data are based
on samples collected at dournstream locations, they are conlparable to data representative of
PELs Appendix A Page 3 of21 Last Revised by EO July 8, 2007
Roarins Fork WSD WWTF Effluent Lirnits PEL-200229
upstream water quality. A summary of these data is presented in Error! Reference source not
found..
In-stream Standards
Table A-2
for Stream Segment COUCRF03a
Physica I a nd B iolog ical
Dissolvcti Oxygen (DO) = 6 mg/l, minimum (7 mg/j, minimum dtrring spawring)
pH:6.5 - 9 su
Fecal Coliform chronic :200 colonies/100 ml
E. coli chronic : 126 coloniesi 100 ml
';; :lll.,:: |,rnorg anii,
Un-ionird arnrnonia acute and chronic : TVS
Chlonne acute : 0.019 mgil
Chlorine chronic : 0.011 mgil
Free Cyanide acute:0.005 mg/i
Sulfide chronic :0.002 mgll
Boron chronic :0.75 mgll
Nitrite acute :0.05 mg/l
Nitrate acute = 10 mg/1
Chloride chronic = 250 mg/l
Sulfate chronic : WS
Total Recoverable Arsenic acute = 50 p-e/l
Dissolved C-admium acute for trout and Dissolved Cadmium chronic : TVS
Total Recoverable Trivalent Chromium acute : 50 pgll
Dissolved Hexavalent Chromium acute and chronic : TVS
Dissolvcd C-opperacute and chronic: TVS
Dissolved lron chronic = WS
Total Recoveruble Iron chronic : 1000 pgll
l)issolved Lead acute and chronic : TVS
Dissolved Manganese chronic = WS
Dissolved Manganese acute and chronic:TVS
Total Mercury chronic :0.01 pg/l
Dissolved Nickel acute and chronic : TVS
Dissolved Selenium acute and chronic : TVS
Dissolved Silver acute and Dissolve d Silve r chronic for trout : TVS
Dissolved Zinc acute and chronic : TVS
PELs Appendix A Page 4 of21 Last Revised by EO .tuly 8, 2007
Roaring Fork WSD WWTF Preliminary Effluent Limits PEL-200229
Table A-3
Ambient \\/ater Oualitv for the Roaring Fork River
$-ffi ii
:.. i; i' i,.. t)th: I
':P.iiciiitili
r::i ):i,. if.:::,:::r!;.:i:J
...':il: 1.iiI:i:ji: :1::-i rr ::,
. : .,a-:-:'.:.--'',, -. ,:. :, i::, iith,,'; ','
i"'ri"iriiii,,
t:-r i.l lli:r ',
.r. t.-:t.:1, i:.,t ::, r.::
' . Mean. '.
.:ljr r.irr:j r,!::::r: :;: !:rr,:i
r.'::':'l' --
Terrp ("C)2 7.9 8.8 9.6 aa 2C
pH (su)2 8.2 8.4 8.6 8.4 6.5-9
Fecal Coljform (#/ I 00 nil)2 83 l13 142 104 2N I
NH:, Tot (mg/l)2 0.01t 0.015 0.060 0.035 NA 2
Nole 1: The calculaled nrean is the geometric mean. Note that for summarization puposes, the value of one was uxd where
there was no detectable amount bccaue the geometric mean cannot bc calculated using a value equal to zero-
Note2: Whensampleresultswcrebelorvdetectionlevels.the valueol'zerowasusedinaccordancewiththe Division'sstandard
approach for summarization and averaging purposes.
Ambient Water Ouality for the Tributan,Wetlands
The Division evaluates ambient water quaiity based on a \/ariety of statistical methods as prescribed
in Section 31.8(2)(a)(i) and 31.8(2XbXiXB) of the Colorado Departntent of Public Health and
Ent,ironnrutt Water Quality Control Commission Regulation No. 3I . The ambient water quality was
not assessed for the Wetlands Tributary because the background in-stream low flow condition is
zero, and because no ambient \\rater quality data would exist at this low flow.
III. Water Quantity
The Colorado Regulations specify the use of low flow conditions when establishing water quality
based ef{luent limitations, specifically the acute and chronic iow flows. The acute low flow, referred
to as 1E3, represents the one-day lou, flow recurring in a three-year interval. The chronic low flow,
30E3, represents the 3O-day average low flow recurring in a three-year interval.
Lorv Flow Analvsis for Discharge to the Roaring Fork River
To determine the low flows available to the Roaring Fork W&SD WWTF, USGS Gage Station
0908 1 000 (Roaring Fork River Near Emma, CO) located upstream from the facility was used. This
gage station provides a conservative analysis of the low flows available to the Roaring Fork W&SD
W'WTF because several tributaries contribute flow to the Roaring Fork fuver between the gage
station and the Roaring Fork W&SD WWTF point of discharge. The local Water Commissioner
confimred that although there are ten "diversions of significance" between USGS Gage Station
09081000 and the facility, inflow from the Crystal River, alone, rvould contribute more than the ten
major diversions take out. Thus, using the upstream gage u,ithout correction results is a conservative
estimate of the low flows availabie to the Roaring Fork W&SD WWTF. A consenative anaiysis is
adequate for this PELs study because the process required to subtract and to add in the various
diversions and inflows to reflect the actual low flow avaiiabie to the facility u,ouid be resource
jntensive and would not change the outcome of this analysis.
PELs Appendix A Page 5 of21 Last Revised by EO July 8, 2007
Roaring Fork WSD WWTF Preliminary-e!{iy.rt t-i*itt PEL-200229
Daily flows frorn the USGS Gage Station 09081000 u,ere obtained and the amrual 1E3 and 30E3 low
flows rvere calculated using U.S. Envirorrmerrtal Protection Agency (EPA) DFLOW software. The
output fron DFLOW also provides calculated acute and chronic low flows for each month.
Flow data from March 12,1998 through September 30, 2006 w'ere available from the gage station.
The gage station and timg fiames rvere deemed the most accurate and representative of current flows
and were therefore used in this analysis.
Based on the 1ow flow analysis described previously, the upstream low flows available to the
Roaring Fork W&SD WWTF were calculated and are plesented in Table A-4.
Table A-4
Lorv Florvs for the Roaring Fotk
i'llr ll
,, :,,1 l
sep:Oct,
r'...:,::.
Noi
_ _,,,,,:,t,
Dec:"
183
Acute 135 141 135 153 174 231 311 228 22s 22't 2t7 180 r40
30E3
Chronic
135 141 135 153 175 258 346 228 2?5 227 217 180 140
During the months of January through March and July through December, the acute low flow
calculated by DFLOW exceeded the chronic low flow. In accordance with Division standard
procedures, the acute low flow was thus set equal to the chronic low flow for these months.
Low Ftou'Analvsis for Discharqe to the Tributarv Wetlands
Cro.ntty, it is the Division's standard approach to assume that there is no available dilution in a
wetiands area until such time as a mixing zone study has been completed that demonstrates the
available dilution. Thus, for purposes of this analysis, low flows are summarized in Tabie A-5'
Table A-5
Lorv Flows for the Tributary Wetlands at the Roaring Fork W&SD WWTF
'.1,1i:::
ri::il I r'iiitii
Jil:,Jep 'i':Obt Nov .:.Dec
1E3
Acute
0 0 0 0 0 0 0 0 0 0 0 0 0
30E3
Chronic
0 0 0 0 0 0 0 0 0 0 0 0 0
PELs Appendix A Page 6 of2l Last Revised by EO July 8, 2007
:::llll
',i1.,:
rt
vr!...
U
Roaring Fork WSD WWTF Prelim Effluent PEL-Z00229
IV. Technical Analysis
5r-stream backg:'ound data and low florvs evaluated in Sections II and III are ultimately used to
determine the assimilative capacity of the Roaring Fork River and the Tributary Wetlands near the
Roaring Fork W&SD WWTF for pollutants of concem. For all parameters except ammonia, it is the
Division's approacir to conduct a technical analysis of stream assimilation capacity using the lowest
of the monthly low flo\a,s (referred to as the annuai lorv flow) as calculated in the low flow analysis.
For ammonia, it is the standard procedure of the Division to delermine assimilative capacities for
each month using the monthly low florvs calculated in the low flow anaiysis, as the regulations allow
the use of seasonal flows when establishing assimilative capacities.
The Division's standard analysis consists of steady-state, mass-balance calculations for most
pollutants and modeling for pollutants such as ammonia. The mass-balance equation is used by the
Division to calculate the maximum allou,able concentralion of pollutants in the effluent, and
accounts for the upstream concentration of a pollutant at the existing quality, critical low flow
(minimal dilution). effluent flow and the water quality standard. The mass-balance equation is
expressed as:
Where,
= Upstream low flow (1E3 or 3083): Average daily effluent flow (design capacity): Downstream flow (0 + 8): ln-stream background pollutant concentrations at the existing quality
: Calculated maxintum allowable effluent pollutant concentration
: Maximum allowable in-stream pollutant concentration (water quality standards)
MtOt- MtOrAr=-- gr:
Q,o,
Qt
Mt
Mz
Mt
When Q1 eeuals zero, as is the case when the wetlands is used as the receiving waters, Q2 e\uals Qj,
and the following results:
Mz= Ms
Because the low flow (Q) for the Tributary Wetlands is considered to be zero, the assimilative
capacity of the rvetlands for the pollutants of concern is equal to the in-stream water quality
standards.
For discharge to the Roaring Fork River, the upstreatn background pollutant concentrations used in
the mass-balarice equation u,ill vary based on the regulatory definition of existing ambient u'ater
qlaiity. For most polJutants, existin-e quality is determined to be tl're 85th percentile. Forpathogens
such as fecal coliform and E. coli, existing quality is delermined to be the geometric mean.
PELs Appendix A PageT of27 Last Revised by EO July 8, 2007
J
Roaring Fork WSD WWTF Prelimi Effluent Limits PEL-200229
For non-conservative parameters and ammonia, the mass-balance equation is not as applicable and
thus other approaches are considered rvhere appropriate. A more detailed discussion of the technical
analysis for these paranieters is provided in the pages that foliow.
Pollutants Evaluated
fto fotto*ing parametels were identified by the Division as pollutants to be evaluated for this
facility:. BODs. TSS
. Percent removal
. Oil and Grease
.pH
. Fecal Coliform
. E, coli. Total Residual Chlorine
. Ammonia.
There are no in-stream water quality standards for BODs, TSS, percent removal, and oil and grease
for the Roaring Fork fuver or the Tributary Wetlands. Thus, assimilative capacities were not
determined for these parameters in this section and an antidegradation review for these parameters
was not conducted in Section V. The evaluation of applicable limitations for these pollutants can be
found in Section Vl Regulatory Aralysis.
According to the Ratiottalefor Classifications, Slandards and Designations of the Upper Colorado
River,there are no existing public water supply uses downstream from the Roaring Fork W&SD
WWTF. For this reason, the nitrate standard, which is applied at the point of intake to a water
supply, is not evaluated as part of this analysis.
During assessment of the facility, nearby facilities, and receiving stream water quality, no additional
parameters were identified as pollutants of concem.
Roarin@TheRoaringForkw&SDwwTFis1ocatedintheNE%oftheNE
% of S13, T7S, R89W, 6th P.M.; on County Road 109, north of Carbondale, Colorado; al39o 27'
05" iatitude North and 107 o 16' 07" West iongitude in Garfield County. The proposed design
capacity of the facility is 0.321 MGD (0.5 cfs). Wastewater treatment is proposed to be
accomplished using a mechanical wastewater treatment process. The technical analyses that follow
include assessments of the assimilative capacity based on this design capacity.
Nearbv Sources
An assessment of nearby facilities based on EPA's Permit Compliance System (PCS) database was
conducted. According to PCS, the nearest upstream and downstream dischargers were:
. The Tour of Czrbondale WWTF (COG-584050), u'hich discharges to the Roaring Fork
fuver, approximately five miles upstream of the Roaring Fork W&SD WWTF. Due to the
extremely high dilution ratio afforcied by the Roaring Fork River, it was unnecessary to
model this facility with the Roaring Fork W&SD WV/TF.
PELs Apperrdix A Page B of21 Last Revised by EO July E, 2007
Roaring Fork WSD WWTF Preliminary Effluent Limits PEL-200229
. The Mobile Honre Management Corporation (dba the H Lazy F Mobile Home Park) (COG-
588035), rvhich discharges to the Roaring Fork River approximately two and a half miles
downstream fi'om the Roaring Fork W&SD WWTF. Two other facilities discharge to the
Roaring Fork River dou,nstream frorn the Roaring Fork W&SD WWTF and they are the Ei
Rocko Mobile Home Park (COG588029), rvirich discharges approximately {ive miles
downstream fi'om the facility of concern, and the City of Glenwood Springs WWTF (CO-
0020516), which discharges approxirnately nine miles downstream from the facility of
concern. Due to the extremely high dilution ratio afforded by the Roaring Fork River, it was
not necessary to model these facilities with the Roaring Fork W&SD WWTF.
For discharge to the Roaring Fork River, the ambient water quality background concentrations used
in the mass-balance equation accouut for pollutants of concern contributed by upstream sources;
thus, it was not necessary to model upstream dischargers together with the Roaring Fork W&SD
WWTF when determining the available assimilative capacities in the Roaring Fork River. Due to
the distance traveled, the significmt dilution of the receiving stream and the changes in the
characteristics of the receiving stream, modeling downstream facilities in conjunction with the
Roaring Fork W&SD WWTF uuas not necessary.
For discharge to the Tributary Wetlands, due to the in'stream low flow of zero, the assimilative
capacities durilg times of low flow are not affected by nearby contributions. Therefore, modeling
nearby facilities in conjunction with the Roaring Fork W&SD WWTF was not necessary.
Based on available infornration, there is no indication that other sources were a significant source of
pollutants of concem. Thus, other sources rvere not considered in this assessment.
pH: For discharge to the Roaring Fork River, an evaluation of pH data available forthe Roaring
Fork River near the Roaring Fork W&SD WWTF found that the I5th percentile value was well above
the minimum in-stream water quality standard and the 85th percentile vaiue was well below the
maximum il-stream water quality standard. Because only limited data are available and because
ambient water quality data indicate that no flither controls are needed to meet in-stream pH
standards, a complex evaluation of the assimilative capacity for pH is not rvarranted for this facility,
and the in-stream water quality standards of 6.5-9.0 su are applied.
For discharge to the Tributary Wetlands, the full assimilative capacity of the wetlands for pH was
determined to equal the in-stream water quality standards of 6.5-9.0 su.
Chlorine: The mass-balance equation rvas used to deten-nine the assimilative capacity for chlorine.
There ale no point sources discharging total residual chlorine u,ithin one mile of the Roaring Fork
W&SD WWTF. Because chlorine is rapidly oxidized, in-stream levels of residual chlorine are
detected only for a short distance belou, a sorrce. Ambient chlorine was therefore assurned to be
zeto.
Using the mass-balance equation provided irr the beginning of Section IV, the acute and chronic lorv
flows set out in Section III, the chlorine background concentration of zero as discussed above, and
PELs Appendix A Page 9 of21 Last Revised by EO July 8, 2007
Roaring Fork WSD WWTF Preliminary Effluent Limits PEL-200229
the in-stream standards for chlorine shor.vn in Section II, assimilative capacities for chlorine were
calcglated. The data used anrl the resulting calculations of the allowable discharge concentrations,
M2, vrr- set forth below'
Di to R ver
ffifi**.,, '-
i;,,,8;i;lcfs):1,Qz kfs)8; kfil lV t fue/l)Mj (ntg/l) 'M 2 {ntg/l)
Acute Chlorine r35 0.50 135.5 0 0.019 5.1
Chronic Chlorine 135 0.50 r35.5 0 0.01 l 3.0
Disch@
The full assimilative capacity of the Tributary Wetlands for total residual chlorine was determined to
equal the in-stream water quality standards of 19 ltgll (acute) and 11 pgll (chronic).
Fecal Coliform and E. coli: Available studies indicate thal E. coli,which is a subset of fecal
coliform, is a better predictor of potential human health impacts from waterborne pathogens.
Currently, the Water Quality Control Commission has adopted standards for both pathogens and
intends that dischargers will have the option of either parameter being used in establishing their
effluent limits. There are no point sources discharging these pathogens within one mile of the
Roaring Fork W&SD WWTF. Thus, assimilative capacities were evaluated separately.
Discharee to the Roarins Fork
In the absence of E. coli ambient water quality data, fecal coliform ambient data are used as a
conservative estimate of E. coli existing quality.
Using the mass-balance equation provided in the beginning of Section fV, the chronic low flow set
out in Section IIi, the background concentrations contained in Section I1 and discussed above, and
the chronic in-stream standards fcrr fecal coliform and E coli shown in Section 1I, the assimilative
capacities for fecal coiiform and E. coli were calculated. The data used and the resulting calculations
of the allowable discharge concentrations, M2, are set forth below.
,M,ti (#/100,
:', :':'il):'.:t. I
M z ft/|00: m0.
Fecal Coliform 135 0.s0 r 35.5 r04 200 2 6,120
E. coli 135 0.50 r 35.5 1M 126 6,066
Discharee to the Tributary W
The full assimilative capacity of the Tributary Wellands for fecal coliform was detemrined to equal
the in-stream water quality standard of 200 colonies/100 rnl (chronic). The full assimilative capacity
of the Tributary Wetlan ds for E coli u,as detemined to equai the in-stream u'ater quality standard of
126 colonies/l00 ml (chronic).
Antmonia: The Ammonia Toxicity (AMIV{TOX) Model is a softrvare program designed to project
the dovrrstream effects of ammonia and the ammonia assimilative capacities available to each
PELs Appendix A Page 10 of27 Last Revised by EO July 8, 2007
Roaring Fork WSD WWTF Preliminary Effluent Limits PEL-200229
discharger based on upstream water quality and effluent discharges. To develop data for the
AMMTOX mode1, an in-stream water quality study should be conducted of the upstream receiving
u,ater conditions, particularly the pH and corresponding ternperature, over a period of at least one
year.
There were no data available for the Roaring Fork River near the Roaring Fork W&SD WWTF that
could be used as adequate input data for the AMMTOX model. Therefore, the Division standard
procedure is to rely on statistically-based, regionalized data for pH and temperature compiled from
similar facilities and receiving waters. Upstream ammonia data for each month were not available
for dischzrges to the Roaring Fork River. Thus, the mean total ammonia concentration found in the
Roaring Fork River as summarizedin Table A-3 was used as an applicable upstream ammonia
concentration reflective of each mon&.
The AMMTOX maybe calibrated for a number of variables in addition to the data discussed above.
The values used for the other variables in the model are iisted below:
. Stream veiocity = 0.3Q0 *o
. Default ammonia loss rate :6lday
. pH amplitude was assumed to be medium
. Default times for pH maxinrum, temperature maximum, and time of day of occurrence
. pH rebound was set at the default value of 0.2 su per mile
. Temperature rebound was set at the default value of 0.7 degrees C per mile.
The results of the ammonia analyses for the Roaring Fork W&SD WWTF at both potential receiving
waters are presented in Tables ,4.-6 and A-7.
Table A-6
AN{MTOX l\{odel Results for Discharge to the Roaring Fork River
at the Roaring Fork W&SD W\\/TF
Month Total Ammonia, chronic (mg/l)Total Ammonia, acute (mg/l)
January >45*>45t
February >45*>45*
March >45*>45*
april >45">45*
May >45*>45*
Jrure >45">45*
.Tu1y >45">45*
August >45*>45"
September >45">45*
October >45*>45'
Novetnber >45n >45*
December >45">45*
* - Treated municipal sanitary seirage effluetrt is expected to have a total anmonia concentration less than 45 mg/1.
PELs Appendix A Page 1 I of2i Last Revised by EO July 8, 2007
Roaring Fork WSD WWTF Preliminary Effluent Limits PEL-200229
v.Antidegradation Review
As set out in The Basic Standards and Methodologies of Swface ll'ater, Section 31.8(2)(b), an
antidegradation analysis is required except in cases where the receiving water is designated as "IJse
Protected." Note that "IJse Protected" \l,aters are walers "that the Commission has determined do
not warrant the special protection provided by the outstanding waters designation or the
antidegradation review process" as set out in Section 31.8(2Xb). The antidegradation section of the
regulation became effective in December 2000, and therefore antidegradation considerations are
applicable to this PELs analysis.
According lo lhe Classification-t artd Nwneric Standards for Upper Colorado River Basin and North
Platte River (Plaruting Region l2), stream segment COUCRFO3a is Undesignated. Thus, an
antidegradation review may be conducted for this segment if ner,r, or increased impacts are found to
occur.
For discharge to the Roaring Fork River, the ratio of the flow of the Roaring Fork River to the
Roaring Fork W&SD WWTF design florv is 270:l at low flows. Section 3l .8 (3)(c) specifies that
the discharge of pollutants should not be considered to resuit in significant degradation of the
revieu'able u,aters if the flou, rate is greater than I 00: 1 dilution at low flow. Thus, Section 3 1.8(3)(c)
Table A-7
AMMTOX Model Results for Discharge to the Tributary Wetlands
at the Roaring Fork W&SD W\ryTF
l\{onth Total Ammonia, chronic (mg/l)Total Ammonia, acute (me/l)
January 5.6 19
Febmary 5.6 19
March 5.4 18
April 5.4 18
Mav 5.5 18
June 5.1 19
July 4.4 '19
August 4.7 22
September 4.6 20
October 5.0 19
November 5.5 18
December 5.4 18
PELs Appendix A Page 12 ofZl Last Revised by EO July 8, 2007
Roarins Fork WSD WWTF Preliminarl'Effluent Limits PEL-200229
of the re-uulations is met and no further antidegradation evaluation is necessary for discharge to the
Roaring Fork River'
For dischalge to the Tributary Wetlands, however, the antidegradation review must proceed. The
Division's ,inriclegradation SigniJicartce Detennirntionfor New or Increased Water Quality Impacts
procedttral Guidance provides guidance on the determination of new or increased water quality
impacts and significant degradation. Consistent rvith current Division procedures, the baseline w-ater
quality (BWQ) concentrations for pollutants of concem should be established so that it can be used
as part of antidegradation reviews. BWQ is defined by the Division as the condition of the water
quutlty as of Septernber 30, 2000. Furthennore, the Division specifies that BWQ concentration wili
include the influence of the discharger if it u.as in place on September 30,2000. Accordingly, BWQ
concentrations are detemrised based on either downstream arnbient water quality data, or based on
tlie follou'ing equation:
BWQ =
M*Q**Mr,Qr,
Q,n + Qr,
Where,
BWQ :
Q'' :
Mgt, :
eqr :
M.s =
"JJ
\\tren Q,6 eQuals
following results:
Baseline water quality
Upstream low flow during the antidegradation period
Upstream background pollutant concentration at the existing quality during the
anti degradation period
2-year average flow
2 -y ear average e ffl u ent po llutant conc entration
zero, as it is considered to be when the facility discharges to the wetlands, the
BttQ: M,n
To establish M.t, monthly average effluent concentrations available from PCS for flow, fecal
coliform, E. coli,total residual chlorine, and ammonia u,ere used. PCS data for flow, fecal coliform
and total residrial chlodne were obtained for a period of record from October 1998 through
Septernber 2000 and averaged for florv and total residual chlorine, and the geometric mean was
deternrinedforfecalcoliform andE.coli.Forammonia,there'w,ereinsufficientdataavailablebased
on a period of record from October i998 through Septeniber 2000, and thus data for a period of
record from April 1998 through September 2000, r.vhich rvere the only available data during the
antidegradation period, rvere obtained. The average concentrations for each month were then
deternrined and rvele used as the MrX" for the respective month. For E coli, no effluent data were
available and therefore an effluent concentration equal to 0.32 times the fecal coliform effluent
concenfration was used consistent with the Division's E. coli policy'
PELs Appendix A Page 13 of21 Last Revised by EO July 8, 2007
Roaring Fork WSD WWTF Preliminary Effluent Limits PEL-200229
Pursuant to the approach discussed above, the equation for BWQ, and the available data. the BWQ
concentrations for the rernaining potential poilutants of concern, except amtnonia, are set forth in
Table A-8.
Table A-8
BWQ Concentrations for Potential Pollutants of Concern Except Ammonia
For Discharge to the Tributary Wetlands
piii"rhniiitiiiiii#Q"6 kfs);.Qu, kfs)Bwo tY.QS; ;:
Fecal Coliform (#/100 ml)I8 0.019 0 l8 200
E. coli (#/ 100 rnl)5.8 0.019 0 5.8 126
TRC(mgll)0.015 0.019 0 0 0.015 0.01 r
For ammonia, BWQ concentrations are calculated by incorporating the average effluent
concentrations and average flow, and the ambient water quality and low flows for the antidegradation
period into the AMMTOX and determining the maximum ammonia concentration downstream.
In cases where the BWQ concentration exceeds the water quality standard, the calculated BWQ
concenfration must then be set equal to the water quality standard. This occurred for total residual
chlorine.
Determinations of Antidegradation Based Average Concentrations
New or increased impacts on the Tributary Wetlands are expected as a result of this permit issuance
because the concentration or loading based on proposed water quality-based effluent limits
(WQBELs) is greater than the existing permit limit or load for the following pollutants:
. Total ammonia for all months.
Note that the evaluation of the existing permit limit and load and the rvater quality-based effluent
limit zurd load is fur1her discussed at the end of this assessment.
For fecal coliform, E. col.i and total residual chlorine, new or increased inrpacts are not expected to
result from this permit issuance because the proposed water quality-based effluent limits and loads
are ntore stringent than existing linrits and loads, and therefore the antidegradation review process is
concluded for these pollutants.
PELs Appendix A Page 14 of21 Last Revised by EO July 8, 2007
1C
t.[
Roa:tng Fork WSD WWTF Preliminary EllfqllUl1l PEL-200229
For the bulleted pollntants, the antidegradation review procedure must continue to determine if
impacts are significant. Impacts are deemed to be significant if the calculated assimiiative capacity
exceeds the calculated antidegradation-based average concentration (ADBAC). ADBACs are
calculated using the significant concentration threshold (SCT), which is the additional amount of
pollutant above BWQ concentration that rvould not cause significant degradation. Section 31.8
(3Xc) specifies that the discharge of pollutants sirould not be considered to result in significant
degradation of the reviewable waters if one of the follorving summarized conditions is met:
. For bioaccumulative toxic pollutants such as mercury, the new or increased loading froln
the source under review is less than l0 percent of the existing total load to that portion of
the segment impacted
. For all other pollutants
o the flow rate is greater than 100: I dilution at low flow; or
o the new effluent load is less than 15 percent of the remaining assimilative capacity; or
o only a temporary change in water quality will result.
The SCT for most pollutants equals the BWQ concentration plus 15 percent of the remaining
assimilative capacity, and is calculated by the following equation:
SCT : 0.tS x 1reS-BWO) + BWe
Where,
WQS = water quality standard (chronic standard or, in the absence of a chronic standard,
the acute standard)
ADBACs are then determined by re-calculating the mass-balance equation using the SCT in place of
the water quality standard, as in the following equation:
ADBAC =
SCTxQT-M,*Q
Where,
Q, = Upstrean low flow (1E3 or 3083)
8z = Average daily effluent flow (design capacity)
Qs = Downstream flow (Q + Qz)Mt = A.mbient existing water quality concentration (From Section iI)
SCT = Significant concentration threshold
W'lren B7 is equal to z,ero, Q: equais Ql and therefore the follorving equation results:
ADBAC = SCT
Q,
PELs Appendix A Page 1 5 of21 Last Revised by EO July 8, 2007
I
Roaring Fork WSD WWTF Prelimi Effluent Limits PEL-200229
ADBACs for total ammonia are detennined by substituting the SCT in place of the cluonic standard
in the AMMTOX model. The resulting ADBACs for total ammonia are set forth in Table A-9. Note
that ADBACs for ammonia are evaluated based on the AMMTOX model, which generates monthly
ADBACS.
Table A-9
ADBACs for Total Ammonia
For Discharge to the Tributary Wetlands
Month Total Ammonia, chronic
(mell)
January 3.8
February 2.9
March 3.1
April 3.7
Mav 2.8
June 1.8
Julv 3.4
August 2.5
September 3.2
October 3.2
November 2.3
December 2.8
In lieu of being subject to the ADBACs, facilities have the option of selecting non-impact limits
(hIILs), which are concentration limits based on their existing permitted load and the proposed
design flow. By agreeing to meet the NILs, new or increased impacts will not occur and thus
ADBACs will not be required to be considered in CDPS permits. For those pollutants for rvhich
permit limits irave not yet been estabiished, an implicit load allocation is determined and an implicit
permit limit is established. In accordance u,ith the Division's E. coli policy, an implicit limit forE.
coli is determined as 0.32 times the permit limit for fecal colifomi.
For al1 pollurants evaluated, a sumnrary of the existing pennit limits (including irnplicit limits), the
existilg permitted load, the nerv WQBELs, the new WQBEL load, ADBACs, and NILs are
contained in Table A-10.
PELs Appendix A Page i6 of21 Last Revised by EO July 8, 2007
Roaring Fork WSD WWTF Preliminary Effluent Limits PEL-200229
Table A-10
WQBELs, ADBACs, and Non-Impact Limits Summary
For Discharge to Tributary Wetlands
Parameter WQBEL ADBAC Current
Limit
NIL
Fecal coliform (#/100 ml)200 45 6,000 2,0401
E. coli (#/100 ml)126 24 2,000 690'
TRC (m-dl)0.011 0.011 0.038 0.0131
Jan. Total Amm. (mg/l)5.6 3.8 10 3.4
Feb. Total Amm. (mg/l)5.6 2.9 10 3.4
Mar. Total Amm. (mg/l)5.4 3.1 10 3.4
Apr. TotalAmm. (mg/l)5.4 3.7 6.0 2.0
May Total Amm. (mdl)5.5 2.8 6.0 2.0
Jun. Total Amm. (mg/l)5.1 1.8 6.0 2.0
Jul. Total Amrn. (-dl)4.4 3.4 5.0 2.0
Aue. Total Amm. (mdl)4.7 2.5 6.0 2.0
Sep. Total Amm. (mg/l)4.6 J-Z 6.0 2.4
Oct. Total Amm. (mg/l)5.0 3.2 10 3.4
Nov. TotalAmm. (*dl)5.5 2.3 10 3.4
Dec. Total Amm. (m/l)5.4 2.8 10 3.4
I - NIL greater than WQBEL so the WQBEL must apply.
The existing permitted load, the new WQBELs load, and the NIL were calculated using the
following equations:
Existing permitted load = Mpermiucd x Qpe,miued x 8.34
New WTQBELs load: Mz * Qz x 8.3q
NIL : Existing permitted load + Q2 + 8.34
Where,
Mpermitted : Existing permit limit or implicit permit limit as of September 2000 (mdl)
Qpernnted : Design flow used in the existing permit as of September 2000 (mgd)
Mz : Maximum allowable discharge concentration (mgll)
Qt : Average daily effluent flow (design capacity in mgd)
In the interests of limiting tables to only those explicitly necessary, detailed calculations of the
existing pemritted load, proposed WQBELs load and NIL are not provided. However, the values for
each factor in the equations noted above can be easily found in this assessment and therefore
calculations can be easily verified.
PELs Appendix A Page l7 of?l Last Revjsed by EO July 8,2007
Roaring Fork WSD WWTF Preliminary Effluent Limits _PEL-200229
\rI. Regulatory Analysis
Reguiation No. 62, the Regulationsfor EJfluent Limitalions, inch.rdes effluent limitations that apply
to all discharges of wastervater to State rvaters, with the exception of storm water and agricultural
retum flows. These regulations are applicable to the discharge from the proposed Roaring Fork
W&SD WWTF. Table A-11 contains a summary of these limitations.
Table A-11
Specific Limitations for the Discharge of Wastes
7.Dn7Aye!ogg,,;
BODs 45 ms./l 30 mgll NA
TSS, mechanical Plant 45 me/l 30 msll NA
TSS, aerated lagoon 110 me/l 75 me/l NA
TSS, non-aerated lagoon 160 ms/l 105 ms/l NA
BODs Percent Removal Na 8s%NA
TSS Percent Removal NA 8s%NA
Total Residual Chlorine NA NA 0.5 mdl
pH NA NA 6.0-9.0 su range
Oil and Grease NA NA 10 men
Note that the TSS limitations shown above vary based on the type of wastewater treatment processes
used at the facility. The Regulations for Efiluent Limitations waive the 85 percent removal
requirements for TSS where waste stabilization ponds, both aerated and non-aerated, are used as the
principal process for treating domestic wastes.
Section 62.4(l) of the Regulations for Efiluent Limitations also indicates that numeric limitations for
fecal coliform shall be determined. The State has developed the Procedurefor Selection of Fecal
Cotifurm Lintitations Permit Conditions that specifies a 30-day geometric mean limit of 6,000
colonies per 100 ml and a7 -day geometric mean limit of 12,000 colonies per 100 ml when the ratio
of the receiving stream flow to design flow is greater than ten to one. The Procedurefor Selection of
Fecal Cotiform Limilations Perntit Conditions also specifies that the 7-day geometric mean limit
must be calculated as two times the 30-day geometric mean limit. Comparably, for E coli,lhe
Division establishes the 7-day geometric mean limit as two times the 3O-day geometric mean limit
and also includes maximum limits of 2,000 colonies per 100 ml (30-day geometric mean) and 4,000
colonies per 100 ml (7-day geometric mean).
PELs Appendix A Page 18 of21 Last Revised by EO July 8. 2007
Roaring Fork 1MSD WWTF Prelimi
VtI. Preliminary Effluent Limits
The potential PELs reflected in Tables A-12 a:rd A-13 include the consideration of the following:
. Assimilalive capacities as disctissed in the technical analysis contained in Seclion IV
. ADBACs as discussed in the antidegradation review provided in Section V (applicable to
discharge to the Tributary Wetlands, only)
NILs, as discussed in Section V (applicable to discharge to the Tributary Wetlands, oniy)
Effluept iimits prescribed by the regulations based on tl,re regulatory analysis provided'in
Section VI.
a
a
Table A-12
Proposed Roaring Fork'l[i&SD WWTF Expansion
Preliminarl,Effluent Limits for Dis.hr.g. to th.
BODs (mgll)45 (7-day average), 30 (3Gday average)
BODs (% rcrnoval)85 (30-day average)
TSS. rrrchanical Plant (mg/l)45 ('7-dav averase),30 (30-day average)
TSS, rrrechanical plant (o/o rernoval)85 (30-day average)
Oil and Ct-ease (mg/l)l0 (rnaximum)
oH (s.u.)6. 5-9.0 (mrr imum-nraximu m)
Max Cap or WQBEL
: ll
', @. 1 0096 :Dil ulion'':
Fecal C-o liform (#/ I 00 ml)I 2OQO (7 -day g eonrean ),
6000 (30-dav georrrcan)
NA NA
E. coli (#i i00ml)4000 (7-day georrran),
2000 (30-dav geornean)NA NA
Total Residual Chlorine (mgll)0.5 (daily maxirrn:m),
Report (30-day average)
NA NA
,VQBEL@,1 00,%o,,:
:' .Dilution,,ADBAC.
:,1 ::il,.:r,::,ri:
NIL.
Total A rrrnonia, (mgll)Rep o n (daily rnaximum),
Report (30-day average)NA r.NA
PELs Appendix A Page 19 of21 Last Revised by EO July 8, 2007
Roari Fork WSD WWTF Preliminarv Effluent PEL-200229
Table A-13
Proposed Roaring Fork W&SD WWTF Expansion
Preliminarl,Etluent Limits for Discharge to the Triburary Wetlands
BODs(mg/l)45 (7-day average), 30 (30-day average)
BODs (% renroval)85 (30-day avcrage)
TSS, rnechanical plant (mg/l)45 (1-day average). 30 (30-day avemge)
TSS, nrechanical plant (% renror,al)85 (30-day averase)
Oil and Crease (mgll)l0 (maximum)
DO me/t)Report (minimum)
pH u 6.5-9.0 (min imurrrmaximum)
Il{ox Cap,or ll'QBEL,
" @100%Dilution'l
IADBAA.NILs
Fecal Coiiform (#/ 100 ml)400 (7-day geomean),
200 (30-dav seorrpan)NA NA
E. coli (#/100 ml)252 (7-day georrean),
126 (30-day geonrean)NA NA
Total Res idual Chlorine (mg/l)0.01 9 (daily rnaximum),
0.011 (3O-dav averaqe)NA tt\A
NIL
Total Arnrnonia, January (mg/l)l9 (daily maximum),5.6
(30-dav averuse)3.3 (2-yr average)3.4 (3Gday georrran)
Tota l Arrrnonia, February (mg/l)l9 (daily rrnximum), 5.6
(3O-day average)3.3 (2-yr average)3.4 (30-day georrean)
Total Arrn-nonia, March (mgll)l8 (daily rrnimum),5.4
(30-dav averase)3.3 (2-yr average)3.4 (3Gday geornean)
Total Annnonia, April (mgll)18 (daily rrnximum), 5,4
(30-dav averaee)3.3 (2-yr avcrage)2 (30-day georrran)
Total Arrnrrcnia, May (mg/l)lB (daily rnaxirrnrm), 5.5
(30-day average)2.5 (2-yr average)2 (30-day georrrean)
Total Annrronia, June (mgll)l9 (daily nraximum), 5.1
(30-dav averaqe)2.5 (2-yr average)2 (30-day georrean)
Total Anrnonia, July (mgll)l9 (daily rrmximum), 4.4
(30-day average)3 (2-yr average)2 (30-day georrrcan)
Total Arrrnonia, August (mgll)27 (daiy nraximum),4.7
(30-day averase)3 (2-yr average)2 (30-day georrnan)
Total Arrn:nonia, Sep tember (mgll)20 (daily rrnximum), 4.6
(30-dav averase)3 (Z-yr average)2 (30-day geonrean)
Total Arrnrrcnia, October (nrg/l)l9 (daily nnximum), 5
(3Gdav averaqe)2.5 (.2-yr average)3.a (30-day georrnan)
Total Arrnrmnia, November (mg/l)l8 (daily rnaximum), 5.5
(30-day averaqe)2.5 (2-yr average)3.4 (30-day geornean)
Total Arrrrronia, December (mg/l)18 (daily rnaximum). 5.4
(30-day average)3.3 (2-yr average)3.4 (30-day geonrean)
PELs Appendix A Page ?0 of2i Last Revised by EO July 8, 2007
;r':.. .j.r , .,
Orher Pollutanls' ,' . ...
a.' ', , ' . l_. : .'
Antitbiia:,: ';, '
Roaring Fork wSD wwrF Preliminary Effluent Limits PEL-200229
For discharges to the Roaring Fork River, the more stringent total residual chlorine, fecal coliform
and E. coii limits, as set forth in the Regulatory Analysis Section VI, are included as PELs as they are
nrore slringent than the effluent limits for these parameters prescribed in the Section IV Technical
Analysis. AIso, limitations for ammonia rvere not necessary for discharge to the RoaringFork River
because the assimilative capacity of the receiving water, as discussed in Section [V, is large enough
to establish total amrnonia effluent concentrations Ior all months at 30 mg/l. Because treated sanitary
sewage efJJuent is not expected to have a total amrnonia concentration greater than 30 mg/I, no
additional ailocations \x,ere determined as per Division procedure and monitoring, only, is specified.
For discharges to the Tributary Wetlands, the more stringent total residual chlorine, fecal coliform
and E. coli water quality-based effluent limits, as set forth in the Technical Analysis Section fV, are
included as PELs as they are ntore stringent than the effluent limits for these parameters prescribed
in the Regulatory Analysis Section VI. Furthermore, as explained in the RegulatoryAnalysis Section
VI, the fecal coliform and E. coli 7 -day geometric mean limits are two times the 30-day geometric
mean limits, respectively, as per Division procedures.
A determination of which PELs ultimately apply will be dependent on decisions made by the
Roaring Fork W&SD WWTF.
V[I. References
Classificolions and Numeric Standards for Upper Colorado River Basin and North Platte River
(Planning Region l2), Regulation No.33, CDPHE, WQCC, effective september l,2oo7.
The Basic Standards and Methodologies for Surface ll/ater, Regulation 3/, CDPHE, WQCC,
Effective December 31, 2005.
Antidegradation Significance Determination for New or Increased Water Quality Impacts,
Procedural Guidance, CDPHE, WQCD, December 2001.
lulemorandum Re: Ftrst Update to Guidattce l/et'sion 1.0, CDPHE, WQCD, Apil23,?002.
Upper Colorado River Basin Regulation No. 33 Triennial Rulemaking Rational, CDPHE, WQCD,
effective May 6,2003.
Policy Concerruing Escherichia coli ver"sus Fecal Colifornt, CDPHE, WQCD, July 20,2005.
Procedurefor Selection of Fecal Coliform Limitations Pennit Conditions,CDPHE, WQCD, April T,
1976.
Regulationsfor Efiluent Lintitations, Regnlation 62, CDPHE, WQCC, December 30, 1998.
\./PELs Appendix A Page 21 of21 Last Revised by EO July 8, 2007
22.5(2)(c) Analysis of existing treatment works
The existing waste water treatment facility was constructed in 1996 for the golf course
development of Aspen Glen. At the time, Garfield County required that the facility be
planned as a regional facility and create a water and sanitation district. The Roaring Fork
Water and Sanitation District was created and the WWTF was master planned to be a
regional facility. During the original planning of the WWTF, odors were a concern because
oflne close proximity of possible development, as a result, all of the processes are covered
and odor control was installed. The odor control system that was installed has not been
operated a great deal because odor has not been a problem.
The facility was originally master planned to be built in three phases of 0.107 MGD for an
ultimate buildout of 0.321 MGD. The facility was designed such that it could easily be
expanded by just adding aeration basins and clarifiers. The WWTF is an activated sludge
facitity with secondary ilarification, tertiary filtration, chlorine disinfection, aerobic digestion
of the bio-solids, and the effluent discharges to wetlands that are adjacent to the Roaring Fork
River. In 1996, the first phase of 0.107 MGD was completed and now is currently using
roughly 55% of the capacity and is meeting the discharge limits. The District does not have
an inflow or an infiltration problem So no un-accounted flows were projected.
The peak month 30-day average flows for 2007 so far was 59,000 gallons per day in the
-onih of August, which is approxim alely 55o/o of the facility's permitted capacity. The peak
month 30-day average organic loading or BOD for 2007 so far was 66.8 pounds per day
which is appioximately 30"/o of the facility's permitted capacity of 225lbslday. A copy of
the WWTF's annual report for 2OO7 is attached as figure 3. The hydraulic and organic
loadings would suggest that the facility is under loaded and there is not a need for an
expansion but as described in more detail in the service area section of this report, the
District is anticipating an accelerated growth rate over the next several years. The District
believes in order to continue to operate within the discharge permit; the facility must be
constructed and online as soon as possible.
As mentioned previously, the WWTF discharges directly to wetlands that are adjacent to the
Roaring Fork River. Because of the discharge location, the curent discharge limits are very
stringent but the WWTF has had no problem in meeting the limits. The facility has had no
issuei with per:rnit compliance and has operated well within the limits. The new PELs that
were received will be very hard to meet during certain months of the year when this facility
is receiving increased flows. As a result, the Board of Directors has decided to look at the
option of discharging to both the wetlands and the river. TlTe District is considering a
pipeline to the river with an outlet into the wetlands. The pipeline would be operated in such
a fashion that during the months when the District is confident it can meet the discharge
limits it would discharge to the wetiands and the remainder of the time it would be directly
discharged to the river. This option willbe explored further wl-ren the design of this phase
stafis.
I:\1996\96059\A-82 WWTF Expansion Planning\2 - WWTF Expansion Permitting\Reg 22 Final.doc
Page 6 of 72
x
=u
UJ
Figure 3
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ii
Go
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EG
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fzzr
22.5(2)(0 Schedule
A schedule in the form of a timeline is shown in figure 7. The process design report
application will be submitted in February of 2008. SGM will prepare design drawings and
contract documents for 6 months, from October 2007 through March 2008, resulting in
approval by CDPHE by May, 2008. The bid process will commence in mid-June and
construction is anticipated to be completed in May 2009.
Estimated Construction Time
The estimated time to construct the proposed facilities from the start of construction to start-
up is 12 months
Estimated Start-Up Date
The predicted start-up date is June 2009.
I:\1996\96059\A-82 WWTF Expansion Planning\2 - WWTF Expansion Permitting\Reg 22Final.doc
Page 9 of 12
Figure 7 - WWTF Expansion Schedule
I:\1996\96059\4-82 WWTF Expansion Planning\2 - WWTF Expansion Permitting\Reg 22 Final.doc
Page 10 of 12