HomeMy WebLinkAbout2.0 Staff Report 10.16.00BOCC r0lt6/00
PROJECT INFORMATION AND STAFF COMMENTS
REOUEST: Review of the Town of Silt Site Application for
construction of a sewage treatment works
APPLICANT: Town of Silt
I. Description of the Proposal
The Town of Silt is proposing to replace the existing discharging sewage treatment
facility with a newer and larger facility, at a locatio4r apprgximately a quarter mile west of
existing treatment facility. (See application pgs. +l{ ) The exiiting facility is an aerated
stabilization pond, designed for a 30-day average daily flow of 0.236 MGD. This facility has
had various operational problems over the past few years, which has resulted in the Town being
cited for water quality discharge violations by the Colorado Department of Public Health and
Environment (CDPFIE). So the applicants have investigated other treatment alternatives.
Three alternatives were evaluated based upon a 0.75 MGD phase, with an identical0.75 MGD
expansion footprint to create an ultimate plant size of 1.5 MGD. The three treatment
alternatives evaluated were :
1) Conventional extended aeration activated sludge
2) Oxidation ditch technology
3) An Aero-Mod activated sludge treatment system utilizing automated headworks,
front clean bar screen with manual back-up bar screen, selector, aeration and
aerobic digesting processes located within cast-in-place concrete tanks. The
process may utilize the existing primary treatment lagoon if additional nitrogen
and phosphoreus removal is necessary.
The third alternative was selected over the other two, based on an evaluation of the systems done
by a team selected to evaluate the alternatives. The team selected the Aero-Mod system based
on the Town of Silt's goals and objectives which included redundancy of processes, high
II.
A.
treatment standards, flexibility and process operation, cost effective capital and O & M costs,
nutrient removal, small footprint, expandability, easy construction installation, energy efficiency,
easy process operation, simplification of ordering materials and equipment, and accelerated
design time. The system also had the lowest cost per gallon per day treated at54.70lgallonlday
treated, or at total cost of $3.32 million for a 750,000 gpd plant.
Issues and Concerns
Process: A site application is reviewed locally by the Board of Count Commissioners
and Board of Health. The Board of Health in a statutory county is the Board of County
Commissioners. These entities are asked to answer the following question:
"Are the proposed facilities consistent with the Comprehensive Plan and any other plans,
policies, andlor regulations for the area, including the 201 Facility Plan or 208 Water
Quality Plan, as they affect water quality?"
These entities are responsible for making a recommendation to the State Department of
Health and Environment, Water Quality Division. The Division in turn makes a
recommendation to the Colorado Water Quality Commission. The Water Quality
Commission has the final approval of any proposed system.
Garfield County Comprehensive Plan: The Garfield County Comprehensive Plan, as
amended in 1984 addresses the use of sewage treatment facilities in the following
mannef:
Water and Sewer Services
Goal: To ensure the provision of legal, adequate, dependable, cost effective sewer and
water facilities and to encourage new development to locate in the proximity to the
existing sewer and water facilities.
Objective # 2: Encourage development locating adjacent to existing subdivisions or
municipalities with available capacity in their central water and /or sewer systems to
become apart of the existing system.
Objective # 5: Discourage the unnecessary proliferation of private water and sewer
systems and special districts.
Policy # 2: Where a logical and economic extension of service lines from an existing
water and /or sewer system can occur, the County will encourage new development
adjacent to or within reasonable distance to serve, to enter into the appropriate
agreements to receive service.
B.
2
C.
Comment: The proposed new sewage treatment facility appears to be consistent with the
Comprehensive Plan goals, objectives and policies, since it is intended to increase the
existing treatment capacity to meet present and future needs.
201 Facilities Plan and 208 Water Oualitv Plan: Garfield County has participated in a
number of 208 Water Quality Plans that encourage the regionalization of sewage
treatment facilities in the area. The proposed facility will increase the treatment
capabilities of the Town of Sitt to meet the demands for sewage treatment projected for
the foreseeable future and it can be expanded to meet greater demands unforseen at this
time. Included in the application is copy of the Town of Silt's 201 Facilities Plan done
in 1979. The proposed treatment facility is not consistent with the 201 Plan, but it is
staff s understanding that the CDPTIE does not consider that an issue, until the Town
requests financial assistance from the State.
CONCLUSION
The Board of County Commissioners and Board of Health recommend approval of the
proposed Site Application for the Construction of new sewage treatment works, as
proposed.
III.
TOVVT\ OF SILT
SITE APPLICATION FOR
WASTNMATER TREATMENT EACILITY
AI.]GUST 2OOO
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COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENV]RONMENT
Water Quality Controt Oivision
4300 Cherry Creek Drive South
Oenver, Colorado 80246-l 530
APPLICATION FOR SITE APPROVAL FOR CONSTRUCTION OF:
A NFff DOMESTIC WASTEWATER TREATMENT PLANT
APPLICANT: Town of Sitt PHONE: 970-876-2353
ADDRESS: 231 North Seventh. P.O. Box 70
CITY, STATE, ZIP: Sitt. Cotorado 81652
Consulting Engineer: Schmueser Gordon Mever. lnc.Phone: 970-945-1004
Address: 118 West 6s Street. Suite 200
City, State, Zip: Glenwood Sorines CO 81601
A. Summarv of lnformation reeardinf, new wastewater treatment olant:
1. Proposed Location (Legal Description): -slL 1 /4, NE 1 /4, Section 9
Township: 6 S Range: 82 W County: Garfietd
Z. Type and capacity of treatment facility proposed: Major Processes Used Manuat and mechanicat bar screcn .
aerobic erit chamber. flash srit removat. flow measurement. extended aeration. activated studee.
nitrification. denitrifcation. secondarv ctarification. disinfection via chtorina6on.
Mrautic: 750.000 gat/day Organic: 1E73 ibe. BODr/day
Pr6ent PE: 1700 D6ign PE: 7500 % Domestic: 95 % lndustriat: 5
3. Location of Facitity:
Attach a map of the area which inctudes the fotlowing:(a) 5-mite radius: all sewage treatment ptants, tift stations, and domestic water supply intakes.(b) l'mile radius: habitabte buitdings, location of pubtic and private potabte water wetts, and an
approximate indication of the topography.
4. Efftuent disposal: Surface discharge to watercoure Colorado River
Subsurface disposal: Land Apptication: _Evaporation:
Other (tist):
State water quatity ctassification of receiving watercourse(s):
Proposed Efftuent Limitations devetoped in conjunction with the Water Quatity Control Division:
BOD, -34[I- mg/t SS 30/45 mg/t Fecal Coliform 6.000/12.0m /1d) mt
Total Residual Chlorine 0.5 mg/t Ammonia N/A mg/t Other _p!,J9:9_l_
5. Will a State or Federat grant/loan be sought to finance any portion of this project? No
6. Present zoning of site area?
Zoning within a 1-mile radius of site? See attached map in Exhibit A
I'\lempool\lom\2000-l 26-00 !.rita applBlDn
WQCD-3a (Revised 2/99)
2*
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APPLICATION FOR SITE APPROVAL FOR CONSTRUCNON OF NEW TREATTAENT PLANT
What is the distance downstream from the discharge to the nearest domestic water suppty intake?
N.rnc of Supply:CiW of Rifle +/- five miles downstream
Addr63 of Suppty:202 Raitroad Avenue. Rifte CO 81650
what is the distance downstream from the discharge to the nearest other point of diversion?
Xarna of U3€r:State Eneineer's Office
Ad(f6r of Usrr:
What entity has the responsibitity for operating the proposed facitity?Town of Sitt
Who owns the land upon which the facitity witt be constructed?Town of Sllt
(Ptc.s. rtuch copi6 of t E dooJrncf,t crcatng authority for thc appticant to cmstruct tha p{opolld facitity at Utis Jitcl
10. Estimated project cosr: 53.53 miltion
Who is financialty resgonsibte for the construction and operation of the facility? T@vn of Sitt
(Piease see attaehed acreement between Town of Sitt and Stittwater Ranch for financina of faciliw.
11.Nam6 and addr$ses of atl municipatiti$ and water and/or sanitation districts within 5 mil6 downstream
of proposed wastervater treatment facitity site.
Ci:trof Rlfle. 202 Raitroad Avenue. Rifle. Colorado 8't650
(attadr r !.9rntr rh€ct of gapaf rf ncccrrary)
12.ls the facitity in a 100 year ftood ptain or other natural hazard area?
lf so, what precautions are being taken?
foot above the 1OO-vear floodolain.
Att flnish ftoor elevations. too of concrete basins. etc.. wilt be ong
Has the ftood ptain been designated by the Colorado Water Conservation Board, Department of Naturat
R6ources or other agency?.Yeq. FFMA
(Ag6rcy Nam.)
lf so, what is that designation? Ftoodotain
13. Ptease identify any additional factors that might hetp the Water Quatity Controt Division make an informed
decision on your apptication for site approvat. This olant is a reolacement for the existinc Town of Silt's
laEoon facititv which is aporoximatetv 2soo'upstream. The oresent Town's laqoon faciliw has beer found in
non- comoliance for discharce oermit oarameters. The tocation of the facititv altows the Town to consotidate
with the orooosed Sti[water Ranch development and Stillwater Metroootitan District.
t\temobct\loo\2o00-l 26{0l.silr ro9tsrion
WOCD-3a (Revised 2/99'\
2 ol4' 6-
APPLICATION FOR SITE APPROVAL FOR CONSTRUCTION OF NEW TREATMENT PLANT
lf the facility will be located on or adJacent to a site that is owned or managed by a federal or st te !86(Y,
send the agency a copy of this applicatlon for the agency's review and recommendation.
Recommendation of governmental authorities:
Ptease address the fotlowing issues in your recommendation decision. Are the proposed facilities consistent
with the comprehensive ptan and any other ptans, poticies, and/or regutations for the area, inctuding the 201
Facitity Ptan or 208 Water Quality Management Ptan, as they affect water quatity? lf you have any further
comments or questions, ptease catt (303)692-3500.
0ate
Recommend
AporovaI
Recommend
Disaoorovat Comment
Signature of
Reoresentative
Ma'ragcmcnt Agcncy
7.
3
City or Tourn (lf site ir inlid€ boundary)
County
t-oc.t Hcatth Authoriry
wttcr Quatity r anagcflicnt Ptannrng agency
I cenify that I am familiar with the requirements of the "Regulations for Site Apptications For Domestic Wastewater
Treatment Work ", and have posted the site in accordance with the regutations. An engineering report, as described
by the reSutations, has been prepared and is enctosed.
Typcd Namc
r !Bmo@ruom\2000-1 25-001.s(6 appheron
WQCD-3a (Revised 2/99)
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EXHIBIT A
Service area definition including existing and projected population, site location, staging or
phasing, flow/loading projections, and relationship to other water and wastewater treatment
plants in the area.
Please find enclosed the Town of Silt Comprehensive Plan Land Use Map. This map
was adopted by the Silt Planning Commission on September 21 , 1999, and revised May 2,
2OOO. This map depicts the urban growth boundary which, at the present time, defines the
Town's Service Area. This map also shows the projected land use and associated densities
with future development within Silt.
Also attached is the Town of Silt population projectionsl, actual and projected, for a
2O-year period. Please note that, based upon a growth rate of five percent annually, the
projected population in the year 2O2O is slightly less than SOOO people. With a growth rate
of seven percent, the projected population is slightly more than TOOO people. Also attached
in Exhibit L is a financial projection, which conservatively projects a growth rate after the year
2OO2 of 200 residential EQRs per year, and eight commercial EQRs per year. Using this
analysis, the amount of residential EQRs is 343O, which translates into a population of 984O.
Assuming 1OO gallons per capita day (gpcd), the 2O-year projected flow contribution will
range from a low of SOO,OOO gpd to a high of 984,000 gpd. Therefore, the plant has been
sized for a mid-range of 75O,OOO gpd expandable to 1 .5 MGD. The doubling of the plant size
will allow for future annexations and infill density to occur in the future.
Also attached in this section is the Garfield County Zoning for the area surrounding the
Town of Silt and the wastewater treatment facility.
1 Western Slope Consulting (Mr. Davis Farrar)
LOM:lc\OO-126.rh
EXHIBIT B
Proposed site location and evaluation of alternative sites.
The proposed wastewater treatment facility site is shown in Exhibit E. The proposed
site is downstream approximately 25OO feet from the existing Town of Silt treatment plant
site. The site is an ideal location for a wastewater treatment facility as it is bordered on the
north by l-7O and on the south by the Colorado River. The site is located further downstream
from the existing site and will allow intervening properties service into the new wastewater
treatment plant site. Presently, the area around the proposed site is undeveloped atthis time.
The site is relatively well screened from the Town of Silt and other developed areas. After
a thorough geotechnical environmental assessment, floodplain and engineering analysis, the
Town had purchased this site.
This site is also downstream from the existing Viking RV Park, which has a non-
conforming ISDS. This site will allow the Viking RV Park to abandon their facility and tie into
the new wastewater treatment facility.
Geotechnical environmental assessment and facilities analysis information is attached
to this report, which indicate the appropriateness of this site for wastewater treatment
purposes.
Currently, the Town of Silt infrastructure gravity-flows across l-70 to the present
wastewater treatment facility. That existing infrastructure can be utilized by tying into the
interceptor sewer prior to the existing wastewater treatment facility and installing a gravity
interceptor to the new treatment plant site.
The other consideration for this site has been the on-going negotiations with the
Stillwater Ranch development. The Stillwater development is a large proposed Planned Unit
Development located adjacent to the Colorado River on the south side of l-7O. The Town of
Silt and Stillwater have investigated varying alternatives for wastewater treatment sites.
Stillwater has investigated installing their own treatment facility located on the south side of
the Colorado River versus consolidation with the Town of Silt. After much negotiations, it
was determined that consolidation with the Town of Silt was the most appropriate alternative.
The selected site allows Stillwater access to the wastewater treatment facility.
Because of the above-mentioned reasons, the Town of Silt focused on this site as the
preferred site. Other sites, including the existing treatment facility site, were evaluated,
however, the positive benefits of the selected site far outweighed any other site in this area.
LOM:Lc\OO- I26.lrh ir ?*
EXHIBIT C
Evaluation of treatment alternatives.
Three treatment alternatives were considered, including the Aero-Mod proprietary
process, conventional extended aeration activated sludge and, finally, the oxidation ditch
technology. Because of the problems the Town of Silt is experiencing with their present
aerated lagoon system, the Town opted to eliminate lagoon technology. The layout for the
pretreatment alternatives are shown as Options 1, 2 and 3 as attached in this section. The
footprint for all three technologies are attached for two phases, each at a 0.75 MGD phase.
This was to determine if the proposed site could accommodate wastewater treatment plant
needs for the Town of Silt well into the future (plant capacily up to 1 '5 MGD). The attached
table shows the capital cost for the Aero-Mod, extended aeration and oxidation ditch
technology. The lowest price per gallon per day treated turned out to be the Aero-Mod
proprietary process at $4.7Olgallon/day treated, or a total cost of #3.52 million for a 75O,OOO
gpd plant.
Also attached is a subjective comparison or matrix of issues between the Aero-Mod
oxidation ditch and extended air plant. Team meetings were held with the Town of Silt
Administrator, operator, Public works Director, Town Engineer and Mr. Jon Evans
representing the EpA. Jon has been involved because of the operational problems associated
with the non-conforming lagoon system.
After considering input from team members, the team decided the Aero-Mod process
met the Town of Silt's goals and objectives. Those goals and objectives included redundancy
of processes, high treatment standards, flexibility and process operation, cost effective capital
and O & M costs, nutrient removal, small footprint, expandability, easy construction
installation, energy efficiency, easy process operation, simplification of ordering materials and
equipment and, finally, accelerated design time. Those goals and objectives and the design
team recommendations were taken to the Town of Silt Trustees over several meetings. The
Town of Silt Trustees concurred and recommended that the Aero-Mod process be selected.
Attached is a proposal from Aero-Mod for the Town of Silt wastewater treatment
facility. This proposal describes in detail the Aero-Mod facility.
LOM:Lc\OO- l26.!xh - /o"
TOWN OF SILT
lunr
SU BJ ECTIVE COM PARISONS
APRIL gTH
AEROMOD
@.nmon wall consfrttdion
stainless steel
no moring parts
low labor
small fo@rint
nubient removal
csrplete rdndancy
strcrt led time
eary intallation
epandable
louodor corplainB
errrgy efficient
esy procsss to operate
wkwith orp marufactrar
lan des(ptirne
lo*erOandMexpense
/-" -.f, r/7// /'
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!'.,/..i t,. 1'/ tdJ''''',7'
7V'i1't"t :itlrt
OXYDATION DITCH
campus design
varies
mxry moving Parts
rnedium labor
large foo$rint
good ntrtient removal
redunclancY
longer lead tirne
rnaa complex concrete work
expandable
cst have odors
modsrate efficiencY
rsocomPlexto oPerate
nrry manufactrers
nue designtirne
higherOandMexPensa
/-2
-:,./,/r:U"
EXTENDED AIR PLAI{T
cilnpus design
varies
marry movirB parts
high labor
large fooSrint
litfle nutrient removal
reOunOarry
lorB lead tirne
mae complex concrete uork
expandable
lilodorproblem
rnod€fdo efficiency
nse cqrplexto operaten:tyrnruffirrr
trsc docintitn
hi*rarOandMetgqra
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Town of Silt, Colorado
Comprehensive Performance Evaluation
January,2000
Introduqtion
Jon Evans, Contract Operations Specialist from Red Rocks Community College, conducted a
Comprehensive Performance Erraluation (CPD for the wastewater treatment facility of the Town
of Sih in January 2000.
CPEs are conducted on wastewater treatment facilities as a means of assessing whether
factors associated with the administr*ion, design, operation or maintenance ar€ affaaing the
optimal performance of the facilities related to effluent qualrty. The CPE is based on the EPA
Handbook: Retrofittinq POTWs.
A CPE is used to help utilities determine if a plant is capable of meeting State and EPA
requirements for wastewatertreatment without investing in major facility upgrade. The
Operations Specialist also gains valuable information about design limits and operational
practices, as well as becoming acquainted with operators and administrators.
The CPE genentes a prioritized list of perforrrunce limiting factors @LFs), wtrich the facility
should address to mitigate treatment plant problems in achieving maximum treatrnent and to
prevent violations.
The CPE was conducted over a short period of time and does not represent a daailed
engineering shrdy of the facility. The CPE was prompted by request from the Town of Silt.
Facility Information
The wastewater treatment facility is an aerated stabilization pond. It was designed for a 30{ay
average daily flow of 0.236 MGD hydraulic flow and 394lbs.BOD/5 per day organic loading.
The efrluent from the plant discharges to the Colorado River.
The Sih Facility cmsists ofthe following:
I Influest flow meter with totalizer & recorder
t Primary lagoon @ 1,,140,000 gd.
6'depth.
6.1 dap Td.
4-5Hp srrEce aerators
0.84 Ac. sur&ce area
* Secondary lagoon @ 2,100,000 gal
6'depth
8.9 days Td.
4- 3 Hp zurfrce aerator
l.l Ac.
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EXHIBIT E
Analysis of existing facilities within the service area(s).
Attached is a map showing the existing water and wastewatertreatment facilities
within a five-mile radius of the proposed site. Also attached are the approved Well Permits
within a one-mile radius of the proposed site. An analysis of the existing Town of Silt
treatment facility is attached. The EPA conducted a Comprehensive Performance Evaluation
for the Town's wastewater treatment facility. Mr. Jon Evans, Contract Operations Specialist
from Red Rocks Community College, in conjunction with the EPA, conducted a
Comprehensive Performance Evaluation in January, 2000. The CPE is based on the EPA
handbook "Retofitting POTW". Based on this evaluation, the Town of Silt elected to abandon
the present lagoon technology and proceed with the new Aero-Mod technology.
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