HomeMy WebLinkAbout1.0 ApplicationENGINEERING REPORT
For the
Town of New Castle
APPLICATION FOR SITE LOCATION APPROVAL
EXPANSION OF AN EXISTING DOMESTIC
WASTEWATER TREATMENT WORKS
Prepared By
Schmueser Gordon Meyer, Inc.
118 West 6th Street, Suite 200
Glenwood Springs, CO 81601
(970) 945-1004
February, 2008
TABLE OF CONTENTS
Section Page
1.0 EXECUTIVE SUMMARY................:........................................................................... 2 .
2.0 SERVICE AREA AND POPULATION.........................................................................3
3.0 LOADING PROJECTIONS..................................................:...................................... 6
4.0 PRELIMINARY EFFLUENT LIMITATIONS (PELs).....................................................7
5.0 ANALYSIS OF EXISTING TREATMENT WORKS......................................................8
5.1 HEADWORKS..........................................................................................................8
5.2 EQUALIZATION BASIN............................................................................................ 8
5.3 AERATION BASINS (A-Basins)................................................................................ 9
5.4 AEROBIC DIGESTERS...........................:................................................................9
5.5 BLOWERS...............................................................................................................9
5.6 SECONDARY CLARIFIERS..................................................................................... 9
5.7 CHLORINE CONTACT CHAMBER..........................................................................9
5.8 0VERAL FACILITY CAPABILITY.............................................................................9
6.0
ALTERNATIVESANALYSIS................................................:...................................10
6.1 Aero -Mod Sequox Biological Nutrient Removal Process .........................................
11
6.2 Aeration Industries Argos Sequencing Batch Reactor (SBR) ..................................
14
6.3 AnoxKaldnes HYBAS Biological Process.......:....................:...................................15
6.4 Zenon ZeeWeed®Z-MOD-X Membrane Bioreactor.............:.................................16
6.5 Siemens Water Technologies Orbal Biological Nutrient Removal Process ..........:..17
6.6 Alternatives Comparison.........................................................................................18
7.0
CONSOLIDATIONANALYSIS..................................................................................20
8.0
FINANCIAL SYSTEM...............................................................................................
20
9.0
IMPLEMENTATION PLAN AND SCHEDULE...........................................................21
10.0
ESTIMATED CONSTRUCTION TIME AND DATE OF PLANT IN OPERATION.......
21
11.0
SOILS REPORT.......................................................................................................
22
12.0
REVIEW COMMENTS FROM VARIOUS ENTITIES.................................................22
Ih19919312MW141A-0.6 MGD Enpansion\SITE APPLICATION1Site Applioe6on Report.RW Pdw . I -
1.0 EXECUTIVE SUMMARY
The Town of New Castle is submitting this application for the construction of an
expansion to the existing wastewater treatment facility. This report will address all the
elements of and guidelines of the "Regulation No. 22" Guidance Document for the Site
Location and Design Approval Regulations for Domestic Wastewater Treatment Works.
This executive summary will provide a brief description of the key points within the
document.
i
The Town's current permitted capacity is 0.20 MGD and 400 Ibis. BOD per day. In July
of 2007 the Town submitted an amendment of an existing site location approval for an
increase to 0.30 MGD and 625 lbs. BOD per day. After discussions with CDPHE staff
about the Town's intent and timing for this new expansion, CDPHE has put that
amendment on hold for replacement/substitution by this site application for an expansion
of existing domestic wastewater treatment works.
Back in 1997 the 201 Facilities Planning Study was prepared for the Town of New
Castle. Within this document it outlined the Town's existing and proposed populations,
wastewater flow projections, existing plant analysis, and consolidation alternatives. A
review of this study, in conjunction with the estimated 2007 population, indicates that the
Town's population projections established in the 201 Study are still valid, with virtually no
adjustment needed to anticipate the actual population. The number of units currently
plotted and/or approved within the Town is 2673. From the 201 Study and based on
planning areas currently within the Town and possible annexations in the future within
the 201 service area the wastewater treatment facility needs to have a capacity of 1.8
MGD at buildout. This application is recommending the Town plan for the ultimate
buildout of 1.8 MGD over three expansions of 0.6 MGD each.
This report evaluates multiple wastewater processes. Evaluation matrices rank each
process. The recommended process is the KALDNES HYBAS system. This is an
extended aeration integrated fixed film activated sludge process. The KALDNES
process will be preceded by the existing headworks facility which includes both manual
and mechanical bar screens, screenings washer and compactor, vortex grit removal, grit
classifier, flow measurement and equalization basin. New secondary circular clarifiers
will follow the KALDNES process tankage. Disinfection will be changed from liquid
chlorine to ultraviolet disinfection during this expansion and biosolids will be digested
with new aerobic digesters. A new dewatering building will be constructed which will
house a new centrifuge for dewatering stabilized biosolids. The biosolids will be hauled
offsite for ultimate disposal. This report also recommends multiple options for biosolids
management. The South Canyon landfill will accept biosolids to use in a composting
process. The Town already has a land application process in place, but the future
growth of this plant may not allow them to continue this operation. A biosolids
management report is being prepared as part of the Process Design Report.
Once the Town receives approval from CDPHE, design drawings and contract
documents will be prepared by the middle of August 2008, with construction starting in
November 2008 with startup of the facility in January 2010.
191993193128"WA- 0.6 MGD ExpansionGSITE APPLICATIONSite Application Repotl_RWPAx - 2 -
SITE APPLICATION COMPLETENESS CHECKLIST
Modification and Expansion of Existing Domestic Wastewater Treatment Plants
Name of Project: Town of New Castle Wastewater Treatment Expansion
Applicant Name and Address: Town of New Castle, P.O. Box 90, New Castle, CO 81647
Consultant Name and Address: Schmueser Gordon Meyer, Inc., 118 W. a Street, Ste 200
Glenwood Springs, CO 81601
Type of Project: Expansion of an Existing Domestic W WTF
Section
Elements
Addressed on
Complete
Submittal Page
(Division)
(Applicant)
22.5(1)
Application submitted on proper form with recommended
Front Section
action by all applicable local authorities and planning
agencies
22.5(2)
An adequate engineering report which documents the need
Sections 2.0
for the modifications and construction, consistency with
through 10.0
local wastewater facility plans and any approved water
quality management plans. The elements listed below shall
be addressed at a minimum:
22.5(2)(a)
Changes to existing service area, population and loading
Section 2.0 & 3.0
projections
22.5(2)(b)
Proposed additional or modified effluent limitations, as
Section 4.0
developed in coordination with the Division
22.5(2)(c)
Analysis of the performance of the existing treatment works
Section 5.0
22.5(2)(d)
Analysis of alternative means to treat additional loading or
Section 6.0 & 7.0
accomplish necessary process modifications, in accordance
with 22.3(1), including any consolidation alternatives
recommended in the approved water quality management
plan, if the plan recommends no consolidation, that option
does not need to be considered
22.5(2)(e)
Changes in the financial system which will result from the
Section 8.0
proposed modification or expansion, including changes to
the fee structure
22.5(2)(£)
Implementation plan and schedule, including estimated
Sections 9.0 &
construction time and estimated date on which the modified
10.0
or expanded plant will be in operation.
1:\1993\93128W\014\A - 0.6 MGD EXPANSIOMSITE APPLICATION\CHMODW WP.DOC
Page 1 of 2
22.5(3)
The Division may require that the applicant present
Section 11.0
evidence, in the form of a report, containing soils testing
results and design recommendations and prepared by a
Professional Geologist and a Geotechnical Engineer, or by
a professional meeting the qualifications of both
Professional Geologist and Geotechnical Engineer, with an
appropriate level of experience investigating geologic
hazards, stating that the site will support the proposed
facility.
22.5(4)(a)
Review comments on the site application and associated
Section 12.0
engineering reports by the management agency, if different
from other entities listed below
22.5(4)(b)
Review comments on the site application and associated
Section 12.0
engineering reports by the county if the treatment plant is
located in the unincorporated area of the county
22.5(4)(c)
Review comments on the site application and associated
Section 12.0
engineering reports by the city or town if the treatment
plant is located within the boundaries of the city or town
22.5(4)(d)
Review comments on the site application and associated
Section 12.0
engineering reports by the local health authority
22.5(4)(e)
Review comments on the site application and associated
Section 12.0
engineering reports by the water quality planning agency
Page 2 of 2
COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT
Water Quality Control Division
4300 Cherry Creek Drive South
Denver, Colorado 80246-1530
(303)692-3574
APPLICATION FOR SITE LOCATION APPROVAL FOR
EXPANSION OF AN EXISTING DOMESTIC WASTEWATER TREATMENT
WORKS
(Section 22.5, of Regulation No. 22)
Applicant: Town of New Castle Phone: 970-984-2311
Address: P.O. Box 90
City, State, Zip: New Castle, Colorado 81647
Email Address tn.adm@newcastlecolorado.ore
Primary Contact (for project inquiries): Chad Paulson - SCM Phone: 970-945-1004
Consulting Engineer: Schmueser Gordon Mever Phone: 970-945-1004
Address: 118 West 6'" Suite 200
City, State, ZIP: Glenwood S mins Colorado 81601
Email Address chadp@spm-ine.com
A. Summary of information regarding existing wastewater treatment plant
1. Existing Location (Legal Description): NEI/4, SWIM, Section 31
Township: 5S Range: 90W County: Garfield
Lat. 39d 34'9.13" N Long. 107d32'16.5" W for Wastewater Treatment Works
2. Type and capacity of treatment facility proposed: The proposed facility is 0.6 MGD and e
... c u¢IIL6uV11 Uk4lm �
also be used. New processes include flowsplitting, extended aeration through a combination fixed film process KALDNES
nitrification- denitrification, circular clarifiers with mechaincal scraper arms scum removal RAS and WAS SDs UV
disinfection, aerobic digesters, and a dewatering device
Processes Used: Activated Sludge
Hydraulic: 600,000 gal/day (maximum monthly average) Organic: 1821 lbs. BOD5/day
' Present PE: 3474 Design PE: 8600 % Domestic: 95
% Industrial: 5
3. Location of Facility:
I Attach a map of the area, which includes the following:
(a) 5 -mile radius: all sewage treatment plants, lift stations, and domestic water supply intakes.
(b) 1 -mile radius: habitable buildings, location of public and private potable water wells, and an approximate
indication of the topography,
WQCD-3b (Revised 6/06) Page 1 of
4. Effluent disposal: Surface discharge to watercourse (name) Colorado River
Subsurface disposal N/A Land Application N/A Evaporation N/A
Other (list): N/A
5. What is the distance downstream from the discharge to the nearest domestic water supply intake? 7 miles
Name of Supply: Town of Silt
Address of Supply: 231 N. 7th Street, Silt, Colorado 81652
What is the distance downstream from the discharge to the nearest other point of diversion? 3 miles
Name of User: Lower Cactus Valley Ditch
Address of User: Silt. Colorado
6. Will a State or Federal grant/loan be sought to finance any portion of this project? Yes
7. Estimated project cost: $5.2 Million
8. Present zoning of site area? Commercial
Zoning within a 1 -mile radius of site -define designation(s)? City/Town, ASRace gricultural/Residential/Rural Density, Open
9. Who owns the land upon which the facility will be constructed? Town of New Castle
(Please attach copies of the document creating authority in the applicant to construct the proposed facility at this site.)
10. Who has the responsibility for operating the proposed facility? Town of New Castle
11. Who is financially responsible for the construction and operation of the facility? Town of New Castle
12. Names and addresses of all municipalities and water and/or sanitation districts within 5 -miles downstream of the
proposed wastewater treatment facility site. Mountain Shadows Subdivision/Apple Tree Park, 5033 County Road 335
New Castle, Colorado, 81647
(Attach a separate sheet of paper if necessary)
13. Is the facility in a 100 -year flood plain or other natural hazard area? Yes, the site is within the 100 year flood plain
If so, what precautions are being taken? The existing site has been enclosed with a berm along the west side of the site
along Elk Creek. The top of the berm is P above the 100 year flood elevation
WQCD-3b (Revised 6/06) Page 2 of
Has the flood plain been designated by the Colorado Water Conservation Board, Department of Natural Resources, or
other agency? FEMA
(Agency Name)
If so, what is that designation? Zone A
14. Please identify any additional factors that might help the Water Quality Control Division make an informed decision
your application for site approval. This is an 0.6 MGD expansion Construction of this expansion will include
(Attach a separate sheet of paper if necessary)
B. If the facility will be located on or adjacent to a site that is owned or managed by a federal or state agency, send
the agency a copy of this application for the agency's review and recommendation.
C. Recommendation of governmental authorities:
The application shall be forwarded to the planning agency of the city, town, or county in whose jurisdiction(s) the
treatment facility is to be located. The applicant shall obtain, from the appropriate planning agency (agencies), a
statement(s) of consistency of the proposal with the local comprehensive plan(s) as they relate to water quality (subject to
the provisions of 22.3(6).
The application shall be forwarded to the water quality planning agency (agencies) for the area in which the facilities are
to be constructed and for the area to be served by those facilities. The applicant shall obtain, from the appropriate
planning agency (agencies), a statement(s) of consistency of the proposal with any adopted water quality management
plan(s)-
If you have any further comments or questions, please call (303) 692-3574.
I certify that I am familiar with the requirements of the "Site Location and Design Approval Regulations for Domestic
Wastewater Treatment Works". An engineering report, as described by the regulations, has been prepared and is
enclosed.
DaIC Frank Breslin, Mavor
Signature of Applicant* Typed Name and Title
*This form must be signed by the applicant. This form cannot be signed by the Consulting Engineer.
Recommend Approval
Date Yes No
Signature and Title of
Representative
2. Management Agency (if different from entities listed below)
County (if site is located in an unincorporated area of the County)
WQCD-3b (Revised 6106)
Page 3 of 4
3.
City or Town (if site is located within 3 miles of the boundaries of a City or Town)
4.
Local Health Authority
5.
208 Planning Agency
i
WQCD-3b (Revised 6/06) Page 4 of 4
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2.0 SERVICE AREA AND POPULATION
The existing service area has not changed. (See attached service map from 201 study)
The Town has made decisions to follow the more conservative approach of the 201
study and plan for a ultimate buildout of this facility of 1.8 MGD ADF. When future
developments/annexations, present themselves the Town will adjust/allocate the
appropriate EQR's to accommodate the buildout of 1.8 MGD. A review the 201 Study
for the Town of New Castle prepared in 1997, in conjunction with estimated 2006
population, indicates that the Town's population projections established in the 201 Study
are valid, with virtually no adjustment needed to anticipate the actual population.
Therefore, the 201 Study information was used for future Town population estimates.
The present population of New Castle is estimated at 3,450 persons. The average daily
wastewater flow (ADF) was 0.21 MGD over the last 12 months. This equates to a per
capita ADF of approximately 61 gallons per capita day (GPCD).
There are three possible ways to evaluate the capacity needed for the new wastewater
treatment facility, industry standards Table 2-1a (70 GPCD, 3.5 people per unit), historic
data Table 2-1c (61 GPCD, 2.77 people per unit), or a combination of the two Table 2-1 b
(70 GPCD, 2.77 people per unit). All three of these methods are based on the growth
rates as outlined in the 201 report. Using the industry standard numbers doesn't make
sense for the Town of New Castle since the historic numbers are much less. Using only
the historic numbers also doesn't make sense in designing a new wastewater facility
because there is no conservatism built into the flow numbers. Consequently after
discussion with Town staff, the facilities will be designed based on a combination of 2.77
people per unit and 70 GPCD resulting in an overall plant size of 0.60 MGD.
Tables 2-1 a, 2-1 b, and 2-1c indicate the updated information (from the 1997 201 Study)
regarding building permit applications with current information from the Town. It is
anticipated that the need for increased housing for the influx of the oil and gas industry
work force will continue for the next five years and taper off to previously projected
growth rates as the number of gas wells reach the anticipated numbers.
TABLE 2-1a. POPULATION GROWTH PROJECTIONS BASED ON
INDUSTRY STANDARDS
Town of New Castle
Garfield County, Colorado
3.5 POP/UNIT
70 GPD/C
NEW
GROWTH
WW INFLUENT
CUMULATIVE
YEAR POPULATION UNITS
M
(GPD)
UNITS
1990
690
48,300
2000
1,976
46
18.6%
138,320
2003
2,396
83
14.3%
167,720
2004
2,687
75
10.8%
188,055
2005
2,949
75
8.9%
206,430
2006
3,212
75
8.2%
224,805
2007
3,474
260
7.6%
243,180
111993\93128UW141A.0.6 MGD ExpenslonlSITEAPPLICATIOMSIIe Application Raporl_RWPAx
1467
-3-
2008
4,384
100
20.8%
306,880
1567
2009
4,734
100
7.4%
331,380
1667
2010
5,084
100
6.9%
355,880
1767
2011
5,434
100
6.4%
380,380
1867
2012
5,784
100
6.1%
404,880
1967
2013
6,134
85
5.7%
429,380
2052
2014
6,432
80
4.6%
450,205
2132
2015
6,712
75
4.2%
469,805
2207
2016
6,974
75
3.8%
488,180
2282
2017
7,237.
75
3.6%
506,555
2357
2018
7,499
75
3.5%
524,930
2432
2019
7,762
75
3.4%
543,305
2507
2020
8,024
75
3.3%
561,680
2582
2021
8,287
75
3.2%
580,055
2657
2022
8,549
75
3.1%
598,430
2732
2023
8,812
75
3.0%
616,805
2807
2024
9,074
75
2.9%
635,180
2882
2025
9,337
75
2.8%
653,555
2957
2026
9,599
75
2.7%
671,930
3032
2027
9,862
75
2.7%
690,305
3107
2028
10,124
75
2.6%
708,680
TABLE 2-1
b. POPULATION GROWTH PROJECTIONS
BASED ON
COMBINED INDUSTRY STANDARDS
AND HISTORIC
DATA
Town of New Castle
2.77
POP/UNIT
Garfield County,
Colorado
70
GPD/C
NEW
GROWTH
WW INFLUENT
CUMULATIVE
YEAR POPULATION UNITS
N
(GPD)
UNITS
1990
690
48,300
2000
1,976
46
18.6%
138,320
2003
2,621
83
14.3%
183,470
2004
2,851
75
8.1%
199,564
2005
3,059
75
6.8%
214,106
2006
3,266
75
6.4%
228,649
2007
3,474
260
6.0%
243,191
1467
2008
4,194
100
17.2%
293,605 _
1567
2009
4,471
--_100 - -
6.2%
312,995
1667
2010
4,748
100
5.8%
332,385
1767
2011
5,025
100
5.5%
351,775
1867
2012
5,302
100
5.2%
371,165
1967
2013
5,579
85
5.0%
390,555
2052
2014
5,815
80
4.0%
407,037
2132
1A1993i931281AW141A-0.6 MGO EzpansicnlSITE APPLICATIOMSite Appllca6an RepowLRWP.d= - -4-
2015 6,036
75
3.7%
422,549
2207
2016 6,244
75
3.3%
437,091
2282
2017 6,452
75
3.2%
451,634
2357
2018 6,660
75
3.1%
466,176
2432
2019 6,867
75
3.0%
480,719
2507
2020 7,075
75
2.9%
495,261
2582
2021 7,283
75
2.9%
509,804
2657
2022 7,491
75
2.8%
524,346
2732
2023 7,698
75
2.7%
538,889
2807
2024 7,906
75
2.6%
553,431
2882
2025 8,114
75
2.6%
567,974
2957
2026 8,322
75
2.5%
582,516
3032
2027 8,529
75
2.4%
597,059
3107
2028 8,737
75
2.4%
611,601
5.2%
TABLE 2-1c. POPULATION GROWTH PROJECTIONS
BASED ON
2013
HISTORICAL DATA
85
5.0%
340,341
2052
Town of New Castle
5,815
2.77
POP/UNIT
354,703
Garfield County, Colorado
2015
61
GPD/C
3.7%
NEW GROWTH WW INFLUENT CUMULATIVE
YEAR POPULATION UNITS N (GPD) UNITS
1990
690
42,090
2000
1,976
46
18.6%
120,536
2003
2,621
83
14.3%
159,881
2004
2,851
75
8.1%
173,906
2005
3,059
75
6.8%
186,578
2006
3,266
75
6.4%
199,251
2007
3,474
260
6.0%
211,924
1467
2008
4,194
100
17.2%
255,856
1567
2009
4,471
100
6.2%
272,753
1667
2010
4,748
100
5.8%
289,650
1767
2011
5,025
100
5.5%
306,547
1867
2012
5,302
100
5.2%
323,444
1967
2013
5,579
85
5.0%
340,341
2052
2014
5,815
80
4.0%
354,703
2132
2015
6,036
75
3.7%
368,221
2207
2016
6,244
75
3.3%
380,894
2282
2017
6,452
75
3.2%
393,567
2357
2018
6,660
75
3.1%
406,239
2432
2019
6,867
75
3.0%
418,912
2507
2020
7,075
75
2.9%
431,585
2582
2021
7,283
75
2.9%
444,258
2657
I:1199M93128\AW14A
-0.6 MGD Pxponslon\SITEAPPLICATION\Site AppliwUm Reporl_RWPAM
- $ -
2022 7,491 75 2.8%
456,930 2732
2023 7,698 75 2.7%
469,603 2807
2024 7,906 75 2.6%
482,276 2882
2025 8,114 75 2.6%
494,949 2957
2026 8,322 75 2.5%
507,621 3032
2027 8,529 75 2.4%
520,294 3107
2028 8,737 75 2.4%
532,967
The current number of units currently plotted and/or
approved within the Town of New
Castle is 2673. Castle Valley Ranch accounts for 900 units, Lakota Canyon Ranch
accounts for 845 units, Burning Mountain, River Park
and Shibui account for 314 units,
and the remaining 614 units come form town infill.
All three of the above tables show the
2673 units being built out around 2021.
The Town of New Castle will install a wastewater treatment facility that will allow them to
only treat flows for wastewater flows associated with all currently plotted and or
approved projects. In phase 1, they will install a 0.60 MGD facility, a 1.2 MGD facility in
phase 2 and finally a 1.8 MGD facility in phase 3. This 1.8 MGD buildout is consistent
with the lower end of the 201 projections. From the data in Table 2-1 b, using a standard
20 year planning horizon, the plant will be designed for 0.60 MGD. This will give the
wastewater treatment facility flexibility and will give the appropriate time to plan and
construct further expansions. As a reference for the 0.60 MGD capacity, the state
requires expansion planning to commence at 80% (480,000 GPD estimated in 2019)
and to be under construction at 95% (570,000 GPD estimated in 2026).
3.0 LOADING PROJECTIONS
The Town's current permitted capacity is 0.20 MGD and 400 lbs. BOD per day. In July
of 2007 the Town submitted an amendment of an existing site location approval for an
increase to 0.30 MGD and 625 lbs. BOD per day. After discussions with CDPHE staff
about the Town's intent and timing for this new expansion, CDPHE has put that
amendment on hold for replacement/substitution by this site application for an expansion
of existing domestic wastewater treatment works.
Average daily influent flows for 2006 were reported to be 0.201 MGD with the average
influent flow for 2007 (through November) being 0.214 MGD. This leaves approximately
26,000 GPD ADF (under pending permit increase) before the next expansion of the
treatment facility approaches the 80% capacity planning threshold.
In order to get ahead of the growth, the next treatment facility expansion will provide a
20 -year facility. This goal results in the planning and permitting of a 0.60 MGD facility
(0.48 MGD at 80%) for the Town of New Castle. Table 2-1b indicates that the Town
should realize the influent flow of 0.6 MGD in 2028, with planning beginning in 2019, and
construction starting in 2026.
It should also be noted that the 261 study predicts an ultimate service area buildout
capacity of 1.8 MGD. Subsequently the wastewater treatment facility site is being
IA1993\931261AD141A-0.6 MGD ExpensionlSITEAPPLICATIOMSile ApplieNon RepM_RWP.doc - -6-
master planned for a total of three expansions of 0.60 MGD each. Total capacity after
phase 1 will be 0.60 MGD, after phase 2, 1.20 MGD, and after phase 3, 1.80 MGD.
Historically organic loadings have been ±250 mg/l. For the proposed expansions all
loadings will be based on industry standards of 350 mg/I BOD and 350 mg/I TSS. This
equates to 1821 lbs/day of BOD at 0.60 MGD.
4.0 PRELIMINARY EFFLUENT LIMITATIONS (PELs)
Preliminary effluent limitations (PELs) have been established by CDPHE. The PEL
number is PEL-200253 and they were issued on January 28, 2008. (See attached PELs
report) Salinity has been added into these new PELs, in which the Town has decided to
protest the 1 ton/day and ask for the aggregate total of 366 tons per year because during
certain times of the year the 1 ton/year cannot be met. (See attached protest letter)
IM993%9312MA01AA-0.6 MGD E.PansionOTE APPLICATIONOte APPHi fi nReporLRWP.dx -7-
STATE OF COLORADO
Bill Ritter, Jr., Governor
James B. Martin, Executive Director
Dedicated to protecting and improving the health and environment of the people of Colorado
4300 Cherry Creek Dr. S.
Denver, Colorado 80246.1530
Phone(303)692-2000
TDD Line (303) 691.7700
Located in Glendale, Colorado
http:/Avww.cdphe.state.co.us
January28, 2008
Laboratory Services Division
8100 Lowry Blvd.
Denver, Colorado 80230.6928
(303)692-3090
Brandyn Bair
Schmueser, Gordon, Meyer Engineers and Surveyors, Inc.
118 W. 6h, Suite 200
Glenwood Springs, CO 81601
Re: PEL-200253, Proposed Expansion of the Town of Newcastle WWTF
Dear Mr. Bair:
oF•coto
dei
• s
� tele •`
Colorado Department
of Public Health
and Environment
JAN 3 1 2008
SGM
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
proposed expansion of the Town of Newcastle wastewater treatment facility (W WTF). 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 (Table 1) are based on effluent limits for pollutants of concern 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 proposed hydraulic design capacity of 0.6 million
gallons per day (MGD), and discharge to the Colorado River, which is identified as stream
segment COLCLC01, the proposed expansion of the Newcastle WWTF may require an
individual permit.
The total ammonia limits warrant clarification. As explained in the attached document, the total
ammonia water quality -based effluent limits (WQBELs) are based on assumptions, given the
absence of adequate effluent pH and temperature data. This is done per Division standard
procedure and utili2es statistically determined in -stream and effluent pH and temperature
conditions for various types of facilities as inputs to the Ammonia Toxicity (AMMT03) Model.
Table 1
Proposed expansion of the Town of Newcastle "TF
Preliminary Effluent Limits for dischar a to the Colorado River
BODS (mg/l)
45 (7 -day average), 30 (30 -day average)
BODS (% removal)
85 (30 -day average)
TSS, mechanical plant (mg/1)
45 (7 -day average), 30 (30 -day average)
TSS, mechanical plant (% removal
85 (30 -day average
Oil and Grease (LnO
10 (maximum)
A (s.u.
6.5-9.0 (minimum -maximum)
OtherPollutants
Max. Limits or WQBEL
E. coli (#/100 ml)
4,000 (7 -day geomean), 2,000 (30 -day geomean)
Total Residual Chlorine (mg/1)
0.5 (daily max mum), Report (30 -day average)
Monthly Total Ammonia, Jan. —Dec. (mg/1)
Report (daily max mum), Report (30 -day average)
Salinity
1 ton/day (because 400 mg/l increase is exceeded)
Temperature (°C)
Report (7 -day Average)
If you have any questions regarding this matter, please contact me at (303) 692-3608.
Sincerely,
Eric T. Oppelt, P.E.
CDPH&E, WQCD
cc: Kent Kuster, WQCD — Engineering Section
Mark Kadnuck, WQCD — Engineering Section
PEL-200253 file
2
Town of Newcastle WWTF Preliminary Effluent Limits PEL-200253
PRELIMINARY EFFLUENT LEmTS, APPENDIX A
THE COLORADO RIVER
PROPOSED EXPANSION OF THE TOWN OF NEWCASTLE WWTF
Table A-1
Assessment Summary
Name of Facility
Town of Newcastle WWTF
PEL Number
PEL-200253
WBID - Stream
Lower Colorado Basin, Lower Colorado River Sub -basin, Stream Segment
Segment
01: Mainstem of the Colorado River from the confluence with the Roaring
Fork River to immediately below the confluence with Parachute Creek.
COLCLCOI
Classifications
Cold Water Aquatic Life Class 1
Class I a Existing Primary Contact Recreation
Agriculture
Water Supply
Designation
Undesignated
I. Introduction
The preliminary effluent limits (PELs) evaluation for the proposed expansion of the Town of
Newcastle Wastewater Treatment Facility (WWTF), hereafter referred to as the Newcastle WWTF,
was developed by 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 proposed expansion of the Newcastle 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 proposed Newcastle WWTF is located in Garfield County, on the north side of the Colorado
River, near the west end ofNewcastle, Colorado. The proposed Newcastle WWTF would discharge
to the Colorado River. This PEL will assess a discharge to potential receiving waters at the proposed
hydraulic capacity of 0.6 MGD (0.93 cfs).
For discharge to the Colorado River, the ratio of the low flow of the Colorado River to the proposed
Newcastle WWTF design flow is 1,056:1. The nearest upstream and downstream facilities had no
impact on the assimilative capacities available to the proposed Newcastle WWTF. Analyses thus
indicate that assimilative capacitiesof the Colorado River are very _large at this point_
PELs Appendix A Page 1 of 13 EO 1/28/08
Town of Newcastle WWTF Preliminary Effluent Limits PEL-200253
Town of New Castle Area
Figure A-1
Information used in this assessment includes data gathered from the proposed Newcastle WWTF,
WQCD, U.S. Environmental Protection Agency (EPA), and the U.S. Geological Survey (USGS).
The data used in the assessment consist of the best information available at the time ofpreparation of
this PELs analysis.
II. Water Quality
The proposed Newcastle WWTF will discharge to the Water Body Identification (WBID) stream
segment COLCLCOI, which means the Lower Colorado Basin, Lower Colorado River Sub -basin,
Stream Segment 01. This segment is composed of the "Mainstem of the Colorado River from the
confluence with the Roaring Fork River to immediately below the confluence with Parachute Creek."
Stream segment COLCLCOI is classified for Cold Water Aquatic Life Class I, Class la Existing
Primary Contact Recreation, Water Supply and Agriculture.
Statewide Basic Standards have been developed in Section 31.11(2) and (3) of The Basic Standards
and Methodologies for Surface Water to protect the waters of the state from radionuclides and
organic chemicals. In Section 31.11(1) of the regulations, narrative standards are applied to any
pollutant of concern, 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
PELs Appendix A Page 2 of 13 EO 1/28/08
Town of Newcastle W WTF Preliminary Effluent Limits PEL-200253
sediment are such pollutants of concern being discussed by Agricultural and Water Quality Standards
workgroups. In order to protect the Basic Standards in waters of the state, effluent limitations with
monitoring, or "monitoring only" requirements for radionuclides, organics, TDS, or anyparameter of
concern 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 Commission. To simplify the listing of the segment -specific
standards, many of the aquatic life standards are contained in a table at the beginning of each chapter
of the regulations. The standards in Table A-2 have been assigned to stream segment COLCLC01 in
accordance with the Classifications and Numeric Standards for Lower Colorado River (Planning
Region 11). Note that the terms of and associated values that correspond to TVS and WS are further
explained in the regulations.
Table A-2
In -stream Standards for Stream Segment COLCLCOI
Dissolved Oxygen DO = 7 mg/l, minimum
H=6.5-9su
Escherichia coliform = 126 colonies/100 ml
Tem erature = 20 C. Max. Weeld Avg.)
Ammonia ac/ch = TVS
Chlorine acute = 0.019 m
Chlorine chronic = 0.011 MWI
Free Cyanide acute = 0.005 ra
Sulfide chronic = 0.002 m
Boron chronic = 0.75 mg/1
Nitrite = 0.5 m
Nitrate - 10 m
Chloride chronic = 250 mRA
r� Sulfate chronic = WS m
�, .,.�.; ,..
Total Recoverable Arsenic acute = 50
Dissolved Cadmium acute and chronic = TVS
Total Recoverable Trivalent Chromium acute = 50
Dissolved Hexavalent Chromium acute and chronic = TVS
Dissolved Copper acute and chronic = TVS
Dissolved Iron chronic = WS
Total Recoverable Iron chronic = 1000
Dissolved Lead acute and chronic = TVS
Dissolved Manganese chronic = WS
-_-_---_----_- __----- - .----Total Mercury chronic= 0,01.
Dissolved Nickel acute and chronic = TVS
Dissolved Selenium acute and chronic = TVS
Dissolved Silver acute and chronic = TVS
Dissolved Zinc acute and chronic = TVS
PELs Appendix A Page 3 of 13 EO 1/28/08
Town of Newcastle WWTF Preliminary Effluent Limits PEL-200253
Standards for metals are generally shown in the regulations as Table Value Standards (TVS),
and these often must be derived from equations that depend on the receiving stream hardness
or species of fish present. The Classification and Numeric Standards documents for each basin
include a specification for appropriate hardness values to be used.
Ambient Water Ouality for the Colorado River
The Division evaluates ambient water quality based on a varietyof statistical methods as prescribed
in Section 31.8(2)(a)(i) and 31.8(2)(b)(i)(B) of the Colorado Department of Public Health and
Environment Water Quality Control Commission Regulation No. 31. Ambient water. quality is
evaluated in this WQA analysis for use in determining assimilative capacities.
To conduct an assessment of the ambient water quality upstream of the proposed Newcastle WWTF,
data were gathered from Division Station 47 (Colorado River at Newcastle), located near the
proposed facility. Data were available from 2000 — 2007 for most parameters. A summary of these
data is presented in Table A-3.
Table A-3
Ambient Water Qualil y for the Colorado River
lNotle
,,��`r`�
meterreenhle.
100 1 NA
NA
^'ercendle+.
NA
„ Men
19
dar11
em °C
20
F. Cott N1100 ml
24 NA
NA
NA
9
126
1
�IH3, Tot m
27 NA I
NA
0
NA
Ns
2
1: The calculated mean is the geometric mean. Note that for summarization purposes, the value of one was used when there was no detectabl
mount because the geometric mean of one is equal to zero.
lme
ote 2: When sample results were below detection levels, the value of zero was used in accordance with the. CO WQCD's standard approach fo
ommarization and averaging u oses.
III. Water Quantity
The Colorado Regulations specify the use of low flow conditions when establishing water quality
based effluent limitations, specifically the acute and chronic low flows. The acute low flow, referred
to as 1 E3, represents the one -day low flow recurring in a three-year interval. The chronic low flow,
30E3, represents the 30 -day average low flow recurring in a three-year interval.
Low Flow Analysis for Discharge to the Colorado River
To determine the low flows available to the proposed Newcastle WWTF, USGS Gage Station
09085100 (Colorado River below Glenwood Springs, CO) located 8 miles upstream from the
proposed facility was used. This gage station provides a reasonable estimate of the low flows
available to the proposed Newcastle WWTF because of its proximity to the proposed WWTF, and
the fact there are no large diversions or tributaries between the gage and proposed WWTF outfall.
Thus, using the upstream gage without correction results is a reasonable estimate of the low flows
available to the proposed Newcastle WWTF.
PELs Appendix A Page 4 of 13 EO 1/28/08
Town of Newcastle WWTF Preliminary Effluent Limits PEL-200253
Daily flows from the USGS Gage Station 09085100 were obtained and the annual IE3 and 30E3 low
flows were calculated using U.S. Environmental Protection Agency (EPA) DFLOW software. The
output from DFLOW also provides calculated acute and chronic low flows for each month.
Flow data from 1997 through 2007 were available from the gage station. The gage station and time
frames were deemed the most accurate and representative of current flows and were therefore used in
this analysis. Based on the low flow analysis described previously, the upstream low flows available
to the proposed Newcastle WWTF were calculated and are presented in Table A-4.
Table A-4
Low Flows for the Colorado River at the proposed Newcastle WWTF
x �kg
yy `.'dd 4l
/.OJy FIOW�2,.
s ,
a
O0 9r
"kiZ F
,
'F'-
�✓��kI
1
�
Apr
J��
�g��
Se
Oc
a ,.5
lts
4
IE3
Acute
Acute
804
828
804
854
968
1,462
1,597
1,411
1,250
1,081
11141
867
805
30E3]
Chron
Chronic
982
982
983
983
1,109
1,462
1,597
1,467
1,250
1,219
1,219
983
:98:3
During the months of May, June, and August 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.
Mixing Zone Considerations
The mixing ratio is > 20:1 dilution and the proposed WWTF will be classified a minor facility
because the design flow is < 1 MGD. Therefore the facility is exempt from finther mixing zone
considerations according to the Colorado Mixing Zone Implementation Guidance.
IV. Technical Analysis
In -stream background data and low flows evaluated in Sections II and Ill are ultimately used to
determine the assimilative capacity of the Colorado River near the proposed expansion of the
Newcastle WWTF for pollutants of concern. For all parameters except ammonia, it is the Division's
approach to conduct a technical analysis of stream assimilation capacity using the lowest of the
monthly low flows (referred to as the annual low flow) as calculated in the low flow analysis. For
ammonia, it is the standard procedure of the Division to -determine -assimilative capacities for each
month using the monthly low flows calculated in the low flow analysis, 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
PELs Appendix A Page 5 of 13 EO 1/28/08
Town of Newcastle WWTF Preliminary Effluent Limits PEL-200253
Division to calculate the maximum allowable concentration 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:
M2= M3Q3 —M1Q1
Q2
Where,
Q, = Upstream low flow (1E3 or 30E3)
Q1 = Average daily effluent flow (design capacity)
Q3 = Downstream flow (Ql + Qz)
Ml = In -stream background pollutant concentrations at the existing quality
MZ = Calculated maximum allowable effluent pollutant concentration
Mj = Maximum allowable in -stream pollutant concentration (water quality standards)
For discharge to the Colorado River, the upstream background pollutant concentrations used in the
mass -balance equation will vary based on the regulatory definition of existing ambient water quality.
For most pollutants, existing quality is determined to be the 85`s percentile. For E. coli, existing
quality is determined to be the geometric mean.
For non -conservative parameters and ammonia, the mass -balance equation is not as applicable and
thus other approaches are considered where appropriate. A more detailed discussion of the technical
analysis for these parameters is provided in the pages that follow.
Pollutants Evaluated
The following parameters were identified by the Division as pollutants to be evaluated for this
facility:
• BODS
• TSS
• Percent removal
• Oil and Grease
• pH
• E. coli
• Total Residual Chlorine
• Ammonia
• Salinity
There are no in -stream water quality standards for BOD5i TSS, percent removal, and oil and grease
for the Colorado River. 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
PELs Appendix A Page 6 of 13 EO 1/28/08
Town of Newcastle WWTF Preliminary Effluent Limits PEL-200253
evaluation of applicable limitations for these pollutants can be found in Section VI, Regulatory
Analysis.
According to the Rationale for Classifications, Standards and Designations ofthe Colorado River,
there are existing public water supply uses in this segment downstream of the proposed Newcastle
WWTF. These are the Town of Parachute (#123602), City of Rifle (4123676) and Town of Silt
(#123710). However, there is significant distance between these water intakes and the proposed
Newcastle WWTF, and large available dilution in the Colorado River. Therefore, the analyses of
parameters for Water Supply classification were not necessary in this PEL.
During assessment of the facility, nearby facilities, and receiving stream water quality, no additional
parameters were identified as pollutants of concern.
_Proposed expansion of the Newcastle WWTF:, The proposed Newcastle WWTF would be located
at 39'4' 9.13" latitude North and 107 ° 32' 16.5" West longitude in Garfield County. The proposed
design capacity of the facility is 0.6 MGD (0.93 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.
Nearby 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 West Glenwood SD WWTF (COG -588008), which discharges to the Colorado River,
approximately 2 miles upstream, and on the other side of the river from the proposed
Glenwood WWTF. Due to the extremely high dilution ratio afforded bythe Colorado River,
it was unnecessary to model this facility with the proposed Glenwood WWTF.
For the proposed discharge to the Colorado River, the ambient water quality background
concentrations used in the mass -balance equation account for pollutants of concern contributed by
upstream sources; thus, it was not necessary to model upstream dischargers together with the
proposed Newcastle WWTF when determining the available assimilative capacities in the Colorado
River. Due to the distance traveled, and the significant dilution of the receiving stream, modeling
downstream facilities in conjunction with the proposed Newcastle WWTF was not necessary. Based
on available information, there is no indication that other sources were a significant source of
pollutants of concern. Thus, other sources were not considered in this assessment.
H.H.. For discharge to the Colorado River, an evaluation of pH data available for the Colorado River
near the proposed Newcastle WWTF found that the 15th percentile value was well above the
minimum in -stream water quality standard and the 85th percentile value was well below the
maximum in -stream water quality standard. Because ambient water quality data indicate that no
further controls are needed to meet in -stream pH standards, a complex evaluation ofthe assimilative
capacity for pH is not warranted for this facility, and the in -stream water quality standards of 6.5-9.0
su are applied.
PELs Appendix A Page 7 of 13 EO 1/28/08
Town of Newcastle WWTF Preliminary Effluent Limits PEL-200253
Chlorine: The mass -balance equation was used to determine the assimilative capacity for chlorine.
There are no point sources discharging total residual chlorine within one mile of the proposed
Newcastle WWTF. Because chlorine is rapidly oxidized, in -stream levels of residual chlorine are
detected only for a short distance below a source. Ambient chlorine was therefore assumed to be
zero.
Using the mass -balance equation provided in the beginning of Section IV, the acute and chronic low
flows set out in Section III, the chlorine background concentration of zero as discussed above, and
the in -stream standards for chlorine shown in Section II, assimilative capacities for chlorine were
calculated. The data used and the resulting calculations ofthe allowable discharge concentrations are
set forth below.
W BEL for Total Residual Clilorme>�"
Parameter�:5,r:- '>`Q1 c s _ c s xs c s or" Aj'
Acute Chlorine 804 0.93 804.93 y 0 0.019 16.4
Chronic Chlorine 982 0.93 982.93 0 0.011 11.6
Escherichia coli: Available studies indicate that E. coli, which is a subset of fecal coliform, is a
better predictor of potential human health impacts from waterborne pathogens. Because of this, the
Water Quality Control Commission is currently adopting standards statewide for solelyE. coli, and
dropping the fecal coliform standard from segments where it still exists.
Using the mass -balance equation provided in the beginning of Section IV, the chronic low flow set
out in Section III, the background concentrations contained in Section II and discussed above, and
the chronic in -stream standards for fecal coliform and E. coli shown in Section II, the assimilative
capacities for fecal coliform and E. coli were calculated. The data used and theresulting calculations
of the allowable discharge concentrations are set forth below.
Temperature
The mass -balance equation was used to determine the assimilative capacity or Maximum Weekly
Effluent Temperature (MWET) for temperature. The upstream MWAT for the Colorado River was
determined from the limited data that was collected at USGS Gage 06752800. Data were spaced
too widely apart to establish a standard MWAT so the highest 3 -month summertime average (19
degrees C) was used. The calculations of the annual 7E3 low flow (880 cfs) used the same flow
information as the used in calculating the 1133 and 30E3 low flows.
PELs Appendix A Page 8 of 13 EO 1/28/08
Town of Newcastle WWTF Preliminary Effluent Limits PEL-200253
Using the mass -balance equation provided in the beginning of Section IV, the chronic low flows set
out in Section III, the MWAT as discussed above, and the in -stream standards for temperature shown
in Section II, assimilative capacity for temperature was calculated. The data used and the resulting
calculations of the allowable discharge temperature are set forth below.
k W BEL for Temperature (Degrees '�
Q j , �^
In the Colorado 1ZVer�"-�*'.`�'e;__-,„`.��5 ,';•^'.=�iz't
Parameter Qt (e s)Qz (c/s) (c s MIYAT Standard MWET
Temp. C° 880 0.93 880.93 19 20 966
Salinity: To protect against salinity levels becoming too high in the Colorado River, from
Regulation No. 61, Colorado, "Municipal discharges to any portion of the Colorado River stream
system shall be allowed an incremental increase in salinity of 400 mg/] or less above the flow
weighted averaged salinity of the intake water supply. The maximum incremental increase
requirement, and the requisite demonstration that it is not practicable to meet the incremental
increase requirement, maybe waived in those cases where the salt load reaching the mainstem of the
Colorado River is less than one ton per day or 366 tons per year, whichever is more appropriate."
Ammonia: The Ammonia Toxicity (AMMTOX) Model is a software program designed to project
the downstream effects of ammonia and the ammonia assimilative capacities available to each
discharger based on upstream water quality and effluent discharges. To develop data for the
AMMTOX model, an in -stream water quality study should be conducted of the upstream receiving
water conditions, particularly the pH and corresponding temperature, over a period of at least one
year.
There were data available for the Colorado River near the proposed Newcastle W WTF that could be
used as adequate input data for the AMMTOX model. Upstream ammonia data for all months were
not available for the Colorado River in this area. Thus, the mean total ammonia concentration found
in the Colorado River as summarized in Table A-3 was used as an applicable upstream ammonia
concentration reflective of each month.
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 listed below:
• Stream velocity = 0.3Q°•4d
• Default ammonia loss rate = 6/day
• pH amplitude was assumed to be medium
__ • Default times for_pl maximum,. 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.
PELs Appendix A Page 9 of 13 EO 1/28/08
Town of Newcastle WWTF Preliminary Effluent Limits PEL-200253
The results of the ammonia analyses for the proposed expansion of the Newcastle WWTF at both
potential receiving waters are presented in Table A-5.
Table A-5
AMMTOX Model Results for Discharge to the Colorado River
at the proposed expansion of the Newcastle WWTF
Month
Total Ammonia chronic m 1
Total Ammonia acute m
January
>45*
>45*
February
>45*
>45*
March
>45*
>45*
April
>45*
>45*
May
>45*
>45*
June
>45*
>45*
July
>45*
>45*
August
>45*
>45*
September
>45*
>45*
October
>45*
>45*
November
>45*
>45*
December
>45*
>45*
- i reama mumcipai sannary sewage ettment is expected to have a total ammonia concentration < 45 mg/1.
V. Antidegradation Review
As set out in The Basic Standards and Methodologies of Surface Water, Section 31.8(2)(b), an
antidegradation analysis is required except in cases where the receiving water is designated as "Use
Protected." Note that "Use Protected" waters are waters "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(2)(b). The antidegradation section of the
regulation became effective in December 2000, and therefore antidegradation considerations are
applicable to this PELs analysis.
According to the Classifications and Numeric Standards for Upper Colorado River Basin and North
Platte River (Planning Region 12), stream segment COLCLC01 is Undesignated. Thus, an
antidegradation review may be conducted for this segment if new or increased impacts are found to
occur.
--Far-dis-cltargeto the Colorado—Rtver,aie ratio oflli- low ofthe Colorado River to the proposed
Newcastle WWTF design flow is 1,056:1 at low flows. Section 31.8 (3)(c) specifies that the
discharge of pollutants should not be considered to result in significant degradation of the reviewable
waters if the flow rate is greater than 100:1 dilution at low flow. Thus, Section 31.8(3)(c) of the
regulations is met and no further antidegradation evaluation is necessary for discharge to the
Colorado River.
PELs Appendix A Page 10 of 13 EO 1/28/08
Town of Newcastle WWTF Preliminary Effluent Limits PEL-200253
Regulatory Analysis
Regulation No. 62, the Regulations for Effluent Limitations, includes effluent limitations that apply
to all discharges of wastewater to State waters, with the exception of storm water and agricultural
return flows. These regulations are applicable to the discharge from the proposed Newcastle
W WTF. Table A-6 contains a summary of these limitations.
Table A-6
..� ,S„ecific Limitations for the Discharge of Was
Ykraip¢teY r
xa; s bayverage:<z
BOD 45 m 30 mO
:a
S
tkpin
.�
„MaYrmm
NA
TSS, mechanical lant
45 m
30 m
NA
TSS, aerated ]a oon
110 MR/1
75 man
NA
TSS, non-aerated ]a oon
160 m
105 m
NA
BOD5 Percent Removal
NA
85%
NA
TSS Percent Removal
NA
85%
NA
Total Residual Chlorine
NA
NA
0.5 m
$
NA
NA
6.0-9.0 su range
Oil and Grease
NA
NA
10 m an
Note that the TSS limitations shown above varybased on the type of wastewater treatment processes
used at the facility. The Regulations for Effluent 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(1) of the Regulations forEfjluentLimitations also indicates that numeric limitations for
fecal coliform shall be determined. The State has developed the Procedure for Selection of Fecal
Coliform Limitations Permit Conditions that specifies a 30 -day geometric mean limit of 6,000
colonies per 100 ml and a 7 -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 Procedure for Selection of
Fecal Coliform Limitations Permit 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, the
Division establishes the 7 -day geometric mean limit as two times the 30 -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 1 I of 13 EO 1/28/08
Town of Newcastle WWTF Preliminary Effluent Limits PEL-200253
VI. Preliminary Effluent Limits
The potential PELs reflected in Table A-7 include the consideration of the following:
• Assimilative capacities as discussed in the technical analysis contained in Section IV
• Effluent limits prescribed by the regulations based on the regulatory analysis provided in
Section VI.
For discharges to the Colorado River, the more stringent total residual chlorine and E. coli limits, as
set forth in the Regulatory Analysis Section VI, are included as PELs as they are more stringent than.
the effluent limits for these parameters prescribed in the Section IV Technical Analysis. Also,
limitations for ammonia were not necessary for discharge to the Colorado River because the
assimilative capacity of the receiving water, as discussed in Section IV, is large enough to establish
total ammonia effluent concentrations for all months at 45 mg/l. Because treated sanitary sewage
effluent is not expected to have a total ammonia concentration greater than 45 mg/1, no additional
allocations were determined as per Division procedure and monitoring, only, is specified.
PELs Appendix A Page 12 of 13 EO 1/28/08
g
�1"
�+
�3M�� �c����r,: ProposedexpansronroftheTownofNewcast1e,,WW'I`F
Prelimina ' Effluent Liritits for dischar e'fo
f ,.
theCo7orado Rave ,;�� ,_ �-
BODS (mg/1)
45 (7 -day average), 30 (30 -day average)
BODS (% removal)
85 (30 -day average)
TSS, mechanical plant (m
45 (7 -day average), 30 (30 -day average)
TSS, mechanical plant (% removal)
85 (30 -day average)
Oil and Grease (mg/1)
10 (maximum)
H (s.u.)
6.5-9.0 (minimum -maximum
E. coli (#/100 ml)
4,000 (7 -day geomean), 2,000 (30 -day geomean)
Total Residual Chlorine (mg/1)
0.5 (daily maximum), Report (30 -day average)
Monthly Total Ammonia, Jan. — Dec. (mg/1)
Report (daily maximum), Report (30 -day average)
Salinity
1 ton/da y or 400 mg/1 increase over intake salinity
Temperature (°C)
Report (7 -day Average)
For discharges to the Colorado River, the more stringent total residual chlorine and E. coli limits, as
set forth in the Regulatory Analysis Section VI, are included as PELs as they are more stringent than.
the effluent limits for these parameters prescribed in the Section IV Technical Analysis. Also,
limitations for ammonia were not necessary for discharge to the Colorado River because the
assimilative capacity of the receiving water, as discussed in Section IV, is large enough to establish
total ammonia effluent concentrations for all months at 45 mg/l. Because treated sanitary sewage
effluent is not expected to have a total ammonia concentration greater than 45 mg/1, no additional
allocations were determined as per Division procedure and monitoring, only, is specified.
PELs Appendix A Page 12 of 13 EO 1/28/08
Town of Newcastle WWTF Preliminary Effluent Limits PEL-200253
VIII. References
Classifications and Numeric Standards for Lower Colorado River Basin (Planning Region 11),
Regulation No. 37, CDPHE, WQCC, effective September 1, 2007.
The Basic Standards and Methodologies for Surface Water, Regulation 31, CDPHE, WQCC,
Effective September 1, 2007.
Lower Colorado River Basin Regulation No. 37 Triennial Rulemaking Rational, CDPHE, WQCD,
effective May 6, 2003.
Colorado Mixing Zone Implementation Guidance, CDPHE, WQCD, April 2002.
Policy Concerning Escherichia coli versus Fecal Coliform, CDPHE, WQCD, July 20, 2005.
Procedure for Selection of Fecal Coliform Limitations Permit Conditions, CDPHE, WQCD, April 7,
1976.
Procedures for Conducting Assessments forlmplementation of Temperature Standards in Discharge
Permits, CDPHE, WQCD, Permits Section, 2007.
Regulations for Effluent Limitations, Regulation 62, CDPHE, WQCC, December 30, 1998.
Colorado River Salinity Standards, Regulation 39, CDPHE, WQCC (last update effective 8/30/97)
PELs Appendix A Page 13 of 13 EO 1/28/08
Administration Department
(970) 984.2311
Fax (970) 984.2716
w ..nM dKolorado.org
1888
Mr. David Akers, CWF Program Manager
Mr. Eric T. Oppelt, P.E.
Colorado Department of Public Health and Environment
Water Quality Control Division
4300 Cherry Creek Drive, South
Denver, Colorado 80246-1530
Town of New Castle
P.O. Box 90
450 W. Main Street
New Gide, CO 81647
February 19, 2008
RE: PEL-200253, Proposed Expansion of the Town of New Castle WWTF
Salinity Limit
Dear Eric,
Please note that we are in receipt of your January 28, 2008 correspondence to Brandyn
Bair regarding the Proposed Effluent Limits for the proposed expansion of the Town of
New Castle WWTF. We appreciate your timely response in providing the PELs letter
back to our consultants, Schmueser Gordon Meyer, Inc.
Please note, however, we are providing this letter requesting a reconsideration of the
Salinity limit set in your correspondence of 1 ton per day. As we have not previously
been subjected to the Salinity limit and as there are no practical means of meeting the
limit, we have no choice but to officially request this challenge. We are aware that the
options potentially available to us to reduce salinity are to provide reverse osmosis,
nanofiltration, eltrodiolysis and perhaps softening by chemical precipitation. However,
each of these presents high operation and maintenance costs as well as insurmountable
disposal challenges. As the Town is endeavoring to continue to keep pace with growth
spurred by the demands of the expanding gas exploration and recovery operations in
Garfield County, the Town's financial position continues to wane. Burdening the. Town of
New Castle with a salinity limit, by which no other community that we are aware of
bears, will render the Town financially strapped to even meet current effluent limits.
We thank you in advance for your consideration and ask that if you have any questions,
please don't hesitate to call.
Respectfully,
TOWN E
oh n W►ge'nwz\el
ublic Works Director
Cc: Chad Paulson, SGM
Brandyn Bair, SGM
Tom Schaffer, Field Supervisor, WQCD
5.0 ANALYSIS OF EXISTING TREATMENT WORKS
The following information is a discussion of the individual process trains of the existing
plant as it stands today.
5.1 HEADWORKS
The existing Headworks area can handle flows up to the phase 3 expansion of 1.80
MGD ADF and a Peak Hydraulic Flow (PHF) of 7.5 MGD. The exception is the
screening equipment which will need to be replaced to handle the future flows with a
larger capacity screen approximately 1 MGD ADF. The new screening equipment
should easily fit within the existing channel. This should roughly occur at the current
screen's service life.
Existing equipment included within the Headworks room includes channels, bar screens
and grit removal equipment. Screening is accomplished using a Vulcan Spiral Screen,
Model ESS -390 installed in a 3 -foot wide concrete channel which is paralleled by a a-
foot wide concrete channel with a manual bar screen. Screened flows travel to a grit
tank and storage hopper (Vulcan Vistex A-27) where grit is settled and stored. The grit
pump (Gorman -Rupp Model T4A71 S -B) removes the accumulated grit from the vortex
hopper and pumps it to the cyclone (Vulcan D10LB) and grit classifier (Vulcan ESK-190).
The cyclone removes the majority of the water by rotational force (where the overflow
drains directly into the equalization basin) and deposits the remaining grit slurry into the
classifier inlet where it is washed, separated, dewatered and conveyed to a waste
container located beneath the classifier discharge. Pretreated flow leaves the vortex
chamber through a 12 -inch Parshall Flume installed within a 4 -foot wide concrete
channel and discharges into the equalization basin. Screenings and processed grit are
removed from the plant and taken to the landfill.
5.2 EQUALIZATION BASIN
The Equalization (EQ) Basin has an active volume of 97,300 gallons, with 6" of
freeboard reserved between high level and the headworks gravity outfall. The EQ Basin
is 45.5'x 44'x 16'-4" tall with a maximum side water depth of 9.5'. Using historical plant
flow data, this volume is sufficient to completely attenuate an ADF of 0.5 MGD
(assuming peaking patterns similar to historic patterns). Future flows beyond 0.5 MGD
will be handled by changing the plant loading scheme (i.e. increased pumping to limit
and somewhat attenuate peak flows and loading).
The current operation scheme is for the EQ basin pumps to discharge at the calculated
ADF. This effectively level -loads the plant and allows the basin,to attenuate the
hydraulic and organic peaks. This is accomplished by using VFD motors on the EQ
pumps, which can be turned up to 1.25 times the current ADF. The basin is equipped
with a spare, redundant pump and gravity overflow in case,of emergency power failure.
-The EQ basin -aeration equipment is sized to sustain biologicat processes prior to
secondary treatment at the 0.5 MGD design loading. There is a spare, redundant blower
in place. There are two submersible mixers to maintain particle suspension in the basin;
19199=128WOWA -0.6 MGD ExpanslonSITE APPLICATIONSIIe AppliuUon Rep0r_RWP.d t _ 8 _
5.3 AERATION BASINS (A -Basins)
The New Castle WWTP currently has three A -basins, any of which can be taken offline
for maintenance without interruption of the others. The dimensions are as follows:
Tank 1A: 21'-4" x 30'-6" x 14'-10" h, Liquid depth = 11'
Tank 1 B: 30'x 12'x 13'-10" h, Liquid depth = 12'
Tank 1 C: T-8" x 30'-6" x 14'-10" h, Liquid depth = 11'
The basins have a total volume of approximately 112,245 gallons. This volume will
provide 7.2 hours of hydraulic detention at future peak design flow, and over 13.5 hours
at current ADF. Aeration is accomplished using coarse bubble diffusers installed with a
grid pattern approximately 12 -inches above the tank floor. The aeration system was
designed and furnished by Sanitare.
5.4 AEROBIC DIGESTERS
The existing digester building has two concrete basins. Each basin is 41' x 14' x 12'
deep, for a volume of 6,888 cubic feet (CF) and total 103,040 gallons for both basins.
The Town currently meets 503 Biosolids regulations by adding lime and raising the pH to
meet pathogen destruction criteria for Class B sludge. Lime stabilization requires adding
sufficient lime to raise the sludge pH to 12 after hours of contact.
5.5 BLOWERS
The plant has three centrifugal blowers that are capable of producing 570 SUM each.
This equates to a firm capacity of 1140 SUM with one blower out of service. The
blowers provide process air for the A -Basins and aerobic digesters.
5.6 SECONDARY CLARIFIERS
The facility has two circular up -flow clarifiers (26 -foot and a 32 -foot diameter) for solids
separation. Both are center feed, perimeter discharge types with individual scum boxes
that empty into adjacent collection tanks. Scum is removed through separate suction
piping with a single Penn Valley Double DiscTM pump (Model 3DDSX22) discharging to
the aerobic digester. Return Activated Sludge (RAS) and Waste Activated Sludge
(WAS) is removed from the bottom of each clarifier with three Crown Model P03LB-7B
Self -Priming Centrifugal pumps. These pumps are connected with suction and
discharge manifolds such that any one pump may perform individual RAS or WAS
functions from either clarifier using actuated plug valves and associated cross -piping.
5.7 CHLORINE CONTACT CHAMBER
The existing Chlorine Contact chamber has two serpentine baffled chambers so that
either channel may be taken offline for routine cleaning and maintenance. Each contact
channel is 3 feet wide by 4.33 feet deep with a total length of 124 feet. With this
configuration, each contact chamber can provide 30 minutes of contact time for flows up
to 0.5 MGD.
5.8 OVERAL FACILITY CAPABILITY
The existing facility has sufficient hydraulic and organic treatment capacity for the
permitted (pending) hydraulic and organic loading of 0.30 MGD and 625.5 lbs./day,
1:11993\93UVATUTA-.0.6 MGD Expansion\SITE APPLICATIOMSile Applioa6on Repor!_RWP.dw _ Q _
respectively. While past plant performance (as reported on DMRs) may raise questions
about the actual treatment capacity, a better picture of plant performance can be gained
by looking at the DMRs prior to April 2006 and data from July 2007 on, when effluent
quality was well below permit requirements. The reason the Town had problems is
because they lost their lead wastewater operator and simultaneously the aged RAS
pumps failed, both being critical components to successful wastewater treatment.
Current DMRs (after July 2007) again demonstrate that the plant can adequately treat
peak flow domestic wastes up to 0.50 MGD. Recent upgrades have greatly enhanced
operation and reliability.
For reference purposes, the calculated treatment capacity of each existing process is
summarized in Table 4-1. The capacities listed below only consider one clarifier and
one chlorination chamber in operation, as required for redundancy by CDPHE.
TABLE 5-1. CAPACITY EVALUATION, EXISTING FACILITY
GD) r t I -�
8.50 Influent Pipe
MA-BasinsI0.325
1.0
Peak Flow 4.5 MGD
in
1.50
Peak Flow 4.5 MGD
n
0.50
EQ-Pumpcapacity
5
HRT at peak flow
Clarifier 1 only)
0.4
Loading Rate at peak flow
Digester
0.5
Loading Rate at peak flow
Chlorination
0.50
Basin dimensions at peak flow
6.0 ALTERNATIVES ANALYSIS.
The following treatment alternatives were investigated to accomplish the goals of the
proposed expansion:
• Aero -Mod Sequox Biological Nutrient Removal Process,
• Aeration Industries Argos Sequencing Batch Reactor (SBR),
• AnoxKaldnes HYBAS Biological Process,
• Zenon ZeeWeed Z -MOD -X Membrane Bioreactor,
• Siemens Water Technologies Orbal Biological Nutrient Removal Process
Each system process is discussed in this section, the benefits and disadvantages are
outlined with special regard to the fact the plant site has limited space and orientation.
All of the evaluated treatment systems provide nutrient removal capability (ammonia,
.nitrite, nitrate_and phosphorus�as_ apart _of_the.secondary-freatment process. All of the
process alternatives will be preceded by the existing headworks facility with manual and
mechanical bar screens, screenings washer and compactor, vortex grit removal, grit
classifier, flow measurement and equalization basin.
The AnoxKalnes HYBAS plant was selected as the treatment process. The
AnoxKaldnes process offers the smallest footprint for the least amount of capital
I:\1993\9312BU1014\A - 0.B MGD Expension\SITE APPLICATIOMSite ApplimUon Repart—RW PAW
investment for the first phase. This process also makes covering the basins a smaller
problem. With the smaller footprint it is possible that some of the existing structures may
be utilized in the future where as the larger footprint processes it's probably not feasible.
The AnoxKaldnes process is also a very stable process that can handle very large
fluctuations in plant loading as the Town has historically seen from time to time.
Operationally the AnoxKaldnes plant is run the same way as the current plant, allowing
for a very small operator learning curve, where with other processes the learning curve
would be much greater. Another advantage to using the AnoxKaldnes process is that it
would allow the Town to install more plastic carrier elements to add additional capacity
to help extend the respective phase without starting major construction right away.
Secondary circular clarifiers will follow the KALDNES process.
6.1 Aero -Mod Seguox Biological Nutrient Removal Process
The term Aero -Mod refers to the following treatment components:
Aerated Selector Tank
First Stage Aeration Basins
Second Stage Aeration Basins
Clarifiers
Digesters
The Aero -Mod plant is constructed with poured -in-place concrete tanks utilizing common
wall construction.
The Aero -Mod plant consists of prefabricated equipment that is integrated and tested,
giving a faster construction schedule and allowing for better field assembled product.
The process components are actuated by compressed air and pneumatic lines supplied
by a separate control air system.
Specific descriptions of each process are as follows:
Aerated Selector Tank
The selector tank receives the process flow from the pretreatment area. The selector
tank is equipped with four (4) coarse bubble assemblies, consisting of a ball throttling
valve, a quick disconnect union, a PVC drop pipe with a stainless steel pipe rail
mounting system, allowing quick and easy removal and maintenance of any of the
diffuser assemblies without having to drain the process tank. The ball valve allows for
the diffuser to have their airflow adjusted to provide only the necessary tank stirring, but
not to increase the dissolved oxygen content of the process.
-irst-Stage.AerationBasins---------------_-_ ----- .:--- ---.__
Upon leaving the selector tank, the mixed liquor enters the first stage aeration basin(s).
The basins consist of two tanks. The first stage aeration basins feature coarse bubble
diffusers, arranged on the inner common wall. Each group of four diffusers has its own
riser pipe, with a quick disconnect union and a ball -throttling valve. This allows for the
operator to precisely fine-tune the aeration requirements for the basin, and to equalize
1919981981281AWIMA -.0.8 MGD FxpensionlSITE APPLICATIOWile Applin Um ReporLRWRdw
out any anomalies with the diffusers. By shutting off the ball valve and disconnecting the
union, the diffuser group can be removed from the aeration basin without having to shut
off the aeration system. This allows for easy repairs and/or replacements of any of the
diffuser assembly components. The coarse bubble aeration causes the process flow
through the tank to roll in a circular spiral manner. This spiral process flow trait, coupled
with the slender configuration of the aeration basin, ensures that an optimum plug flow
characteristic minimizes any chance of short-circuiting in the aeration basin. At the end
of the First Stage Aeration Basin, the process flow enters into the Second Stage
Aeration Basin.
Second Stage Aeration Basins
The process stream enters into the Second Stage Aeration Basin, after the First Stage
Aeration Basin. The second stage aeration basin, like the first stage aeration basin,
features coarse bubble diffusers mounted to the outside wall only. These diffusers allow
the tank to roll, as described above, minimizing the any potential short-circuiting of the
process stream.
The Second Stage Aeration Basins feature Aero-Mod's Sequox process, which involves
pneumatically, actuated butterfly valves that cycle the aeration between the two-second
stage aeration basins. A typical Sequox cycle provides aeration to one -second stage
aeration basin for two hours, and then has a two-hour time without any aeration. The
other second stage aeration basin reverses this process, allowing the blowers to
produce the same amount of process air for the plant without having to change its
supplied amount. These two hours on, then two hours off cycles allows the process to
enter an anoxic state, allowing for denitrification.
Clarifiers
After the process has passed through the second stage aeration basins, it then enters
into the clarifier by first passing through a circular inlet screen, to allow for collection of
trash, floatable material, and other inorganic matter that has passed through the
headworks. The process then flows into the clarifier by means of distributor pipes. These
pipes run in a horizontal direction, and have a series of tees, oriented in such that the
tee branch is facing down, allowing for the mixed liquor to exit the distributor pipe and
flow in a downward motion. This directional flow causes the process to begin the
separation process of the clarifier.
Each of the distributor pipes is located above a triangular concrete section. The slopes
of the triangular section are sloped to direct the settling sludge towards the suction
hoods. The suction hoods consist of four stainless steel, trapezoidal shaped boxes that
rest above a trapezoidal concrete section, poured in place below the location of the
suction hoods. This form fitting shape of the concrete section with the suction hoods
,directly above minimizes the free space below the hoods_,_ and therefore minimizing the
cross sectional area normal to the pressure gradient, thus increasing the flow velocity for
the sludge return mechanism. Each suction hood lays flat on the bottom of the clarifier,
and has six slots equally spaced on each side that allows settled sludge to enter the
suction hood, and be returned through the return mechanism. Each suction hood row is
aligned between the triangular concrete sections, as the peak of the triangular section
197993\931281AOM1 A-0.8 MGDExpanslonlSITEAPPLICATIOMSIte Application Report-RWP.doo -12-
represents the highest point in the clarifier bottom, and the slope of the section allows
the sludge blanket easy access to the slots on the suction hood.
Upon operation of the airlift pump, the settled sludge is drawn into the suction hood
through the hood's slots. The sludge is sucked up through the airlift pump, and
discharged into the RAS return channel; which is located directly under the clarifier
bridge walkway. The return channel's flow characteristics function as a rectangular
channel, and return back into the selector tank. A staff gauge allows the operator an
easy visual verification of the flow quantity, based upon a standard rectangular
calculation for spot readings of actual instantaneous return flow. Furthermore, since the
typical operation of the return system is a batched system, when the flow rate is
constant, an effective amount of return can be calculated by knowing the amount of time
the return cycle operates. Since the operator can select the lengths of time for the return
cycles, as well as the intermittent rest cycles, this allows a great range of flexibility of the
RAS rate. Surface Scum is removed by floating scum skimmers.
Digesters
Two digesters are used for sludge stabilization. The digesters have coarse bubble
diffusers located on both sides of the long.dimension of the tank. Airlift pumps from the
first stage aeration basins fill the digesters. The airlift pumps are operated either
automatically by a timer, or manually from the Aero -Mod control panel. During the fill
cycle, the aeration is turned off, and the sludge is allowed to settle, such that only the top
12"-24" of the stratum has a weaker mixed liquor concentration. The airlift pumps are
then cycled on to fill the digesters. Supernatant is returned over a weir to the second
stage aeration basin. This weir sets the water level for the digester. A baffle in front of
this weir harbors foam and scum within the digester, and keeps it from recirculating
throughout the plant.
Advantaoes and Disadvantaae
Advantages include common wall construction; footprint usually favors small sites,
contains no moving parts, very low maintenance process, and doesn't need separate
digesters and clarifiers. Disadvantages.include very large blowers that result in higher
energy costs. In this case the common wall system is too large for current site starting
with the phase 2 construction. The deeper tanks could pose a problem with
groundwater and the covering becomes an issue due to the large structure.
Controls. Operation and Maintenance
Control of an Aero -Mod plant is very easy. In many cases the plant operates with
minimal attention from the operator. If there are problems there operating in hand
becomes very easy. Operation and maintenance costs for the Aero -Mod process are
very high due to the number and size of blowers that are required to run the process.
1Al 993193128UVJ14U-0.6 MGD ExpsnsionOTE APPLICATIO"ile Application ReporL.RW P.dw -13-
6.2 Aeration Industries Argos Sequencing Batch Reactor (SBR)
The ArgosTM SBR plant is constructed with poured -in-place concrete tanks utilizing
common wall construction. This process includes an influent splitter box, SBR process
tanks, and a sludge holding tank.
The Argos SBR is unique to the industry due to the flexibility of the Aire -OZ Triton
aeration system. The use of the Tritons for both aeration and mixing in the SBR greatly
simplifies the design and installation of the SBR system by eliminating piping
infrastructure, supports, and building footprints for blowers that feed traditional diffused
air networks. The Triton aeration system also has the capability of independent mixing
and aeration using the same unit making it very easy to upgrade plants to facilitate
nitrification/denitrification simply by modifying the plant controls. Air injection can be
turned off on the Triton without affecting basin mixing. Other technologies require the
use of additional mixers to ensure complete mix conditions.
The SBR is a fill and draw activated sludge system. In this system wastewater is added
to a single batch reactor, treated, and then discharged. The wastewater enters a
partially filled reactor, containing biomass. Once the reactor is full it acts like a
conventional activated sludge system but without continuous influent or effluent. The
aeration and mixing are stopped after the biological reactions are complete, the biomass
settles, and the treated supernatant is removed. At any time during the cycle the excess
biomass can be removed.
The SBR option eliminates the need for secondary clarifiers and digesters.
Advantages and Disadvantages
Advantages for SBR's include common wall construction, biological treatment that can
be paced with influent flows, low maintenance process, no need for separate digesters
and clarifiers, and design offers good mixing and air transfer due to deeper tanks and
proprietary equipment. Disadvantages with SBR's include treatment all in one tank,
large structure. becomes difficult to cover, deep tanks create problem with groundwater,
computer control with SBR is suspect at best, higher energy costs, and the decant
operation in SBR's is not the same as clarifier performance.
Controls. Operation and Maintenance
Control of an SBR process isn't overly complicated, but the problem arises if the control
system goes down. It is impossible to run an SBR in hand. This is due the treatment all
in.one tank and everything is on a paced or time set schedule.SBR plants also require
a fair amount of operator attention and if someone is not around all the time many things
can and will go wrong. Operations and maintenance for the SBR process is also very
I:\1993\931Y8W101AW-0.6 MGD Espenslon\SITE APPLICATIOMSIIe Appl(c Uw RepwLRWPA= - -14-
high due to the two 75Hp aerator/mixers in each SBR basin and the two 50Hp
aerator/mixers in the sludge holing tank.
6.3 AnoxKaldnes HYBAS Biological Process
The AnoxKalnes HYBAS plant is constructed with poured -in-place concrete tanks
utilizing common wall construction. This process includes an anoxic process tank and
two aerobic process tanks that also contain the plastic carrier elements.
The core of the process is the biofilm carrier elements (wheels) that are made from
polyethylene with a density slightly below water. This allows a small amount of water
(created by adding air to the process) to circulate the media throughout the vessel. The
elements are designed to provide a large protected surface area for the biofilm and
optimal conditions for the bacteria culture when the elements are suspended in water.
AnoxKaldnes have developed carriers of different shapes and sizes which give the,
flexibility to use the best suitable carrier depending on wastewater characteristics, pre-
treatment, discharge standards and available volumes.
Oxygen and food (ammonia and nitrite) gives the bacteria the means to grow, while the
AnoxKaldnes media provides maximum surface area for the bacteria to colonize and
produce bio film. It is this process, which removes harmful ammonia and nitrite from the
water. As the AnoxKaldnes media chaotically circulates within the bio tank, it causes old
dead bacteria/bio film on the outside, to be removed making space for new younger
heavier feeding bacteria/bio films to colonize. Within the wheel, is a protected surface,
which enables colonies of bacteria to naturally follow their life cycle, maturing and dying,
in turn fuelling the latter stages of the nitrification conversion process. it also assists in
the breakdown of any small particles passing through from the mechanical stage.
Therefore, the AnoxKaldnes media maintains both a young bio film and a maturing bio
film providing a more consistent filter performance, while improving water quality.
Due to chaotic movement of the AnoxKaldnes media, the process is self-cleaning and
requires no maintenance. This allows the filter to reach optimum effectiveness without
the disturbance of periodic maintenance, avoiding unnecessary loss of bacteria within
the filter preventing high levels of ammonia and nitrite within the water.
i
The AnoxKaldnes Hybas process is a combination of fixed film and activated sludge.
The Hybas process is run the same as a conventional activated sludge process other ,
than half of the biomass is in suspension and the other half is attached to the plastic
carrier elements. The design would incorporate a pre -denitrification zone to help meet a
total nitrogen effluent concentration of less than 10 mg/I and adding an aeration basin
incorporating the AnoxKaldnes HYBAS biological process for helping increase the
nitrification capacity. In the aerobic zone the plastic media is added for increasing the
nitrification process while not increasing the solids loading rate to clarifiers. For example
the aeration basins would have an effective MLSS concentration of 6000 mg/l, but the
clarifier would only be loaded at 3000 mg/I. This allows the aeration basins to be about
half the size of normal activated sludge plants.
Since the AnoxKaldnes process is operated the same way as a typical activated sludge
plant secondary clarifiers, digesters, and associated piping are still needed.
191993\931281AW14A -A.6 MGD RxPansion1SITE APPLICATIOMSite Application Repcd_RWP.dx- -15-
Advantages and Disadvantages
Advantages for the AnoxKaldnes process include common wall construction with a
smaller footprint, covering becomes more feasible with smaller footprint, and the process
requires very low maintenance. Disadvantages include the need for separate digesters
and clarifiers and aeration tanks contain plastic carrier elements that must be dealt with
for "in -basin" repairs.
Controls. Operation and Maintenance
Control for the AnoxKaldnes process is very similar to the Aero -Mod process. If the
control system goes down the hand operation mode is very simple since there are very
few moving parts. Also with the redundant tanks if some major were to happen fixing the
problem is easy. Operations and maintenance for the AnoxKaldnes process is the
lowest cost per phase due to the tower number of blowers needed for the treatment
process.
6.4 Zenon Zee Weed® Z -MOD -X Membrane Bioreactor
The Z -MOD -X plant is constructed with poured -in-place concrete tanks utilizing common
wall construction and pre-engineered packaged membrane bioreactors. This process
includes anoxic and aerobic process tanks as well as a membrane tank.
The Z -MOD -X system produces a superior effluent quality through a combination of
immersed, low pressure ultrafiltration membranes and a suspended growth biological
reactor. The ultrafiltration membranes replace the solids separation function of
traditional secondary clarifiers and the polishing function of granular filter media that are
typically found at conventional activated sludge facilities. By eliminating the need for
sludge settling the Z -MOD -X process can operate at MLSS concentrations that range
from 8000 —15000 mg/l, three to five times greater than conventional systems, usually
resulting in designs that are more compact. With fewer processes and an automated
PLC, plant operation becomes less labor intensive and much more straightforward. With
this system the plant operators are only required to perform regular maintenance on
system pumps, blowers, and associated mechanical equipment for the membranes.
Routine chemical cleanings of the membranes are essential to long-term operation of
the membranes.
With the membrane bioreactor option it eliminates secondary clarifiers, but will have to
include a building for additional screening (2mm) prior to the membranes to remove
trash and non -biodegradable solids, such as hair, lint, grit and plastics that may foul or
damage the membranes if allowed to pass into the membrane chamber.
Advantages and Disadvantages
Advantages for the membranes include the elimination of secondary clarifiers and the
possibility of a secondary water (re -use) system. Disadvantages for membranes include
additional screening and disposal prior to the membrane tanks, higher maintenance and
IM 993W3128W10141A -0.6 MGD ExpensioMSITE APPLICATIO"He Appl!wUw Reporl_RWP.da -is-
energy costs, larger footprint becomes difficult to cover, and the membrane require more
operator attention.
Controls. Operation and Maintenance
Controls for the membrane process pose a problem if the system were to go down. It is
very difficult to run the process in hand due to all the different systems such as
membrane air scouring, permeate pumping, backpulse pumping, chemical pumping, and
recirculation pumping. Operation and maintenance for membrane treatment process are
also relatively low. It ranks as the second lowest in each of the expansion.
6.5 Siemens Water Technologies Orbal Biological Nutrient Removal
Process
The OrbalT11 BNR plant is constructed with poured -in-place concrete oxidation ditches.
For the oxidation ditch there will be two channels built in phase 1 and one in phase 2.
The Siemens Water Technologies Orbal BNR process is a suspended growth activated
sludge process designed for energy efficient and biological nutrient removal (BNR)
performance. The Orbal activated sludge system is a series of concentric oxidation ditch
channels surrounding a center island. Flow traverses from the exterior channel through
the inner channel to a hydraulically designed outfall structure.
Some advantages of the Orbal BNR system include non -corrosive aeration discs with
highly effective mixing characteristics, minimizing maintenance and energy costs.
Dependable, low maintenance, extended life, pillow block bearings designed for rugged
outdoor applications. Changes in oxygen demand can be easily met by varying the disc
immersion or rotational speed to meet loading conditions while continuing to provide
adequate mixing. The use of the "reactors in series" flow pattern allows the dissolved
oxygen (DO) level to be varied from tank to tank resulting in overall reduced energy cost.
Under normal operation the influent wastewater is directed to the outer basin where it is
mixed with RAS returned from the clarifiers to form the system mixed liquor. The
combined mixed liquor will pass through the outer channel to the inner-most channels
before passing on to the clarifiers and then disinfection. The flow from one Orbal
channel to another will be by displacement of the mixed liquor circulating in each
channel through submerged ports interconnecting adjacent channels. The outer channel
of a typical three -channel Orbal basin is operated with DO levels at or near 0 mg/I.
Because the demand for oxygen is high in the outer channel the supplied oxygen is
utilized immediately and no residual oxygen is available to be measured. Because the
demand for oxygen is lower, the final channel can be maintained in an aerobic state with
a design DO level at 2 mg/I.
Using complete mix reactors in series provides economical, flexible, and reliable
treatment performance. The "reactors in series" arrangement minimizes cost by using
multi -wall construction techniques. Because of the disc aerators mixing capability, there
is no need for additional mixers in the aerated anoxic outer channel. The Orbal BNR
process offers nitrification/denitrification performance, so higher level of total nitrogen
IM 993\9312M\0141A - 0.6 MGD E%pensionOTE APPLICATIOMSile Applic Uon Report_RW PAW -17-
removal can be achieved than in non-aerated anoxic reactors. With these two benefits,
the energy savings of the design is considerable.
The SmartBNR system provides automatic control of the aeration process, enhancing
the nutrient removal capability of the system. By matching oxygen deliver to the actual
oxygen requirements at the plant 24 hours a day, this feature can provide a substantial
energy and labor savings to the owner. The SmartBNR control system is a PLC based
system that provides for partial or complete process control of multi -stage reactor
systems using aerated anoxic processes.
Aeration Control
The first reactor (aerated anoxic) condition is monitored by an ORP analyzer. A
dissolved oxygen analyzer monitors the final stage reactor (aerobic). In systems with
more than two stages, either a DO or an ORP analyzer can monitor the middle stages.
The disc aerators are controlled by means of on/off manipulation or changing the speed
output of the VFD's.
Wastina Control
A total suspended solids (TSS) input from the operator or TSS analyzers placed in the
final stage reactor allow the PLC to calculate the system solids inventory. Similarly, an
input of TSS on RAS concentration or an analyzer in the WAS pipe along with a flow
meter allow the PLC to calculate the mass flow rate of solids wasted. The mass flow
rate is controlled by means of an actuated valve, control valve, or WAS pump. The PLC
continuously adjusts wasting to achieve the selected MCRT (sludge age).
With the oxidation ditch option secondary clarifiers, digesters, and associated piping
would still need to be installed.
Advantaaes and Disadvantages
Advantages for the oxidation ditch include lower energy costs, outer channel can easily
be added in the future, and the process lends itself to better nutrient removal with its
outside to inside flow pattern and oxygen management. Disadvantages include a very
large footprint, separate digesters and clarifiers, and significantly more yard piping.
Controls. Operation and Maintenance
Control of an oxidation ditch is very easy and can be done in hand mode just like the
Aero -Mod and AnoxKaldnes process without having huge affects on the treatment
process. Also since there are separate channels any one channel may be out of
service if problems arise.
.-- 6.6 Alternatives Comparison.
In general any one of the five proposed alternatives would. work. Each option has
advantages, disadvantages, and cost implications associated with it. Below is just a
brief summary of each process with associated plant construction cost and a decision
matrix that was used to select the AnoxKaldnes HYBAS Biological Process.
IA1993\9312MA\014tA-0.6 MGD Expension\SITE APPLICATIOMSIte Applioe6on Repor(_RWP.dw _ -18-
The Aero -Mod design is very simplistic, having the selector tank, aeration basins,
clarifiers, and digesters all in one common wall design. Under most cases this type of
design would lend itself to smaller sites but as the exhibit shows, fitting three Aero -Mod
plants on the current site is just not possible. Preliminary cost estimates show the Aero -
Mod process being the most expensive at $8.42 per gallon between the three phases.
The Aero -Mod process is the most expensive in two out of the three phases and the
second highest in the other phase.
The Aeration Industries SBR design takes out the need for secondary clarifiers and
separate digesters (the SBR design incorporates a common wall sludge holding tank),
but has process tanks that are 24' deep, which is going to be a problem with
groundwater at the current site. Preliminary cost estimates show the SBR process being
the least expensive at ultimate buildout at $5.42 per gallon, but for the phase 1
expansion it is the third most expensive option. The SBR option doesn't provide the
town with the best treatment process. There are many problems associated with
sequencing batch reactors. If the control system quits then the entire process is stopped
and no treatment takes place while the influent flow continues. Treatment all in one tank
isnot desirable. Operator attention is a must with an SBR.
The AnoxKaldnes design offers the smallest footprint which helps with site constraints
and covering basins. This process will still need to include secondary clarifiers and
digesters. In preliminary cost estimates over the three phases the AnoxKaldnes process
will average $6.02 per gallon. From the phased cost analysis the AnoxKaldnes process
is the least expensive for phase 1 and second least expensive for phase 2, and is still
very competitive at phase 3.
The Siemens Orbal design is similar to the AnoxKaldnes design in that this option will
also need secondary clarifiers and digesters. The Orbal design has a relatively large
footprint at complete build out of the oxidation ditches, but fits relatively well with the site.
In preliminary cost estimates the Siemens oxidation ditch has an average plant cost of
$5.72 per gallon between the three phases. The oxidation ditch is the second least
expensive for phase 1, very close to the AnoxKaldnes cost for phase 2, and is the least
expensive in phase 3. This has to due with the fact that in the third phase only aerators
and motors would need to be installed in the ditch along with another digester and
clarifier.
The Zenon Membrane design takes out the secondary clarifiers so this helps with site
constraints, but the buildings/tanks that are required for this process are relatively large.
The membrane option would be a great fit for the town if they plan on installing a re -use
water system in the future. In preliminary cost estimates the Zenon membrane design
has an average plant cost of $8.07 per gallon between the three phases. The
membrane is the most expensive in two out of the three phases and is the second most
expensive in the other phase.
I:\1993\93126U\014W . A.6 MGD Expansion\SITE APPLICATIOMSile Applioe6on Report_RW PAW -19-
Table 1: Decision Matrix For Alternative Treatment Processes
PROCESS
Aeromod
Aeration
Anox-Kaldnes
Siemens
Zenon
Industries SBR
Oxidation Ditch
Membrane
Footprint
5
2
1
3
4
Energy Costs
5
4
1
3
2
Extra Clarifiers
1.5
1.5
4.5
4.5
3
and Digesters
Additional
2.5
2.5
2.5
2.5
5
Screening
Re -use Water
3.5
3.5
3.5
3.5
1
System
Ease of
1
4
2
3
5
Maintenance
(Operator
Attention)
Ease of
5
2
1
3
4
Expandability
and Adaptability
Stability/
2
5
1
2
5
Reliability
Process
1
5
3
2
4
Controls
Overall Cost Per
5
1
3
2
4
Gallon
Rank
3.15
3.05
2.25
2.85
3.70
Overall Rank
4
3
1
2
5
MIFI Illy Jy51en1 t 1-0) 1=ue5[, t)=w0rS1
7.0 CONSOLIDATION ANALYSIS
Consolidation alternatives were discussed in the 201 study. A copy of this report can be
provided upon request. There are two wastewater treatment facilities within the 5 mile
radius of the Town of New Castle's treatment facility, Riverbend to the east and Apple
Tree/Mountain Shadows to the west. Riverbend and Apple Tree/Mountain Shadows
have capacities of 0.0247 MGD and 0.15 MGD respectively. Consolidation of these
facilities would be very difficult for one main reason, geographic location. To
interconnect all three of these facilities would require lift stations to get across the river
and many miles of new interceptor. If and when more development occurs around the
Town of New Castle consolidation of these facilities will be again evaluated.
8.0 FINANCIAL SYSTEM
Copies of New Castle's Utility Fund budget for the construction of this plant are attached.
The budget shows cash flow projections through year 2027. The revenues include the
user charge, contributions from the customer in the means of tap fees, and also late
fees. The expenditures include operations and maintenance, capital outlay, and the
1A19931931231A\0144-0.6 MGD ExpansionOTE APPLICAT10"ile Applioe6on Repor!_RWPAW - - -20-
TOWNOFNEWCASTLE COLORADO
Cash Flow Projection -
Years Ended December 31, 2002 through 2006 Actual
Projections for 2007 through 2027
Expenditures:
Operations and Maintenance
Capital outlay
Debt service
Total Expenditures
Excess (Deficiency) of Revenues over Expenditures
Available Resources: December 31
(Revised December 2006)
}#e - See attached notes
2/1/20089:13 AM
626,662 671,383 684,439 ,705 7,911,660 9,098,409 10,463,171 12,032,647 13,837,544 15,913,175 18,300,151
494,306 514,346 1,686,075 ,000 500.000 500,000 500,000 600,000 600,000 600,000 600,000
-34,617 83,841 -13,131 311 635,565 649,597 664,984 581,928 -38,085 -838,539 -820,372
764,852 848,693 835,562 X264 4,466,829 5,116,426 5,781,410 6,363,338 6.325.253 5,486.714 4666342
Actual
2002
2003
2004
)
2021
2022
2023
2024
2025
2026
2027
Available Resources: January 1
799,469
764,852
848,693
952
3,831,264
4466 829
5,116.426
5 781 410
6,363,338
6 325 253
5.486,714
'.. Revenues:
User charge revenue
510,772
598,925
634,274
,063
7,971,873
9,167,654
10,542,802
12,124,222
13,942,855
16,034,283
18,439,426
Contributions from customers - tap fees
545,125
368,191
507,450
1600
1,460,000
1,460,000
1,460,000
1,460,000
821,250
0
0
Late fees and other
75,937
347,937
1,271,855
,000
265,000
270000
275.000
280,000
285.000
290.000
290,000
Total Revenues
1.131.834 1.315.053
2.413.571
6R3
o Ala Ala
10 nm Asn
» 977 An,
1A ane o,,
,A nen ,n.
,A on. o.o
Expenditures:
Operations and Maintenance
Capital outlay
Debt service
Total Expenditures
Excess (Deficiency) of Revenues over Expenditures
Available Resources: December 31
(Revised December 2006)
}#e - See attached notes
2/1/20089:13 AM
626,662 671,383 684,439 ,705 7,911,660 9,098,409 10,463,171 12,032,647 13,837,544 15,913,175 18,300,151
494,306 514,346 1,686,075 ,000 500.000 500,000 500,000 600,000 600,000 600,000 600,000
-34,617 83,841 -13,131 311 635,565 649,597 664,984 581,928 -38,085 -838,539 -820,372
764,852 848,693 835,562 X264 4,466,829 5,116,426 5,781,410 6,363,338 6.325.253 5,486.714 4666342
Town's debt service. The Town has also included a list of notes that help explain the
projected budget, they include:
1) 2008 Tap fee revenue is per 2008 budget, 175 water and sewer taps.
2) 15% increases for tap fees are included in 2011 ($13800), 2016 ($15870) and
2021 ($18250). These increases are below the current rate of inflation.
3) Tap fee revenue is projected at the following rates: 2009-2011 @ 100/year;
2012-2015 @ 90/year; 2016-2024 @ 80/year and 2025 @ 45/year.
4) User charge revenue and operations and maintenance expenditures are
increased 15% per year, starting in 2010, for the increase in users and inflation.
5) 2009 other revenue includes a $2,000,000 transfer from the General Fund
(loan proceeds to be paid back from increased property tax revenue) and a
$500,000 grant for the water treatment plant and/or wastewater treatment plant
expansions.
6) 2010 — 2013 other revenue includes $500,000 per year developer cash
contributions from future annexations.
7) The $500,000 grant listed in #5 and the developer cash contributions listed in
#6 could be funded by a general fund property tax increase (if approved by
voters), as an alternative.
8) 2010 — 2014 capital outlay includes $500,000/year for the new south sewer
interceptor line.
9.0 IMPLEMENTATION PLAN AND SCHEDULE
Copies of the design schedule are attached. The schedule includes time for preliminary
effluent limits, surveying the site, site application process, process design report, design
drawings and contract documents with review periods, the bid process, construction of
the new expansion, discharge permit, and preparing operation and maintenance
manuals.
10.0 ESTIMATED CONSTRUCTION TIME AND DATE OF PLANT
IN OPERATION
Both the construction time and plant startup can be found detailed within the design
schedule. It is anticipated that design drawings and contract documents will be prepared
by the middle of August 2008, with construction starting in November 2008 with startup
of the facility in January 2010.
Ih199319312M\0WA -. 0.6 MGD ExpensionZITE APPLICATIONOte Appt!wUon RepM_RW P.d= -21-
11.0 SOILS REPORT
The soils report that was used during the construction of the Headworks and
Equalization basin is attached along with a letter from Hepworth Pawlak Geotechnical
stating the site can handle an expansion. Once the Town has completed a new site plan
and is in full design HP Geotech will be contracted to perform further subsurface
investigations in the areas where new tanks will be placed.
12.0 REVIEW COMMENTS FROM VARIOUS ENTITIES
1A1993193128U1014W - 0.6 MGD ExpansionGSITE APPLICATION1SJte Application Reppt_RWP.ft
-22-
GetPtech
HEPWORTH-PAWLAK GEOTECHNICAL
January 10, 2008
Town of New Castle
HepworthrPawlak Geotechnical, Inc.
5020 County Road 154
Glenwood Springs, Colorado 81601
Phone: 970-945.7988
Fax: 970-945-8454
email hpgeo@hpgeotech.com
c/o Schmueser Gordon Meyer
Attn: Brand Bair
118 West 6 Street, Suite 200
Glenwood Springs, Colorado 81601
Job No. 102 122
Subject: Comments Regarding Current Development Plan, Proposed Wastewater
Treatment Plant Expansion, New Castle, Colorado
Gentlemen:
As requested, we are providing comments regarding the current development plan for the
proposed expansion to the New Castle wastewater treatment plant. We previously
performed a subsoil study and provided foundation and grading design recommendations
for a proposed headworks building at the site (Hepworth-Pawlak Geotechnical, Inc.,
2002). We understand that the recommendations provided in the previous report will be
used for planning and preliminary design of the current development plan.
Foundations: The conceptual expansion plan, dated October 3, 2007, was provided by
Schmueser Gordon Meyer. The plant expansion is currently proposed to consist of new
digesters, clarifiers, dewatering building, RAS/WAS building, splitter box, wet wells and
lift station as well as provisions for future expansion. We understand that grading for the
new structures will involve cut depths on the order of 3 to 4 feet below the existing
ground surface.
A total of two pits were excavated at the site as part of our previous study. The subsoils
consist of a variable depth of fill and fine-grained soils overlying relatively dense, silty
sandy gravel, cobbles and boulders at a depth of about 3'/Z feet. Groundwater level was
measured at 5%: and 7 feet below the ground surface in April 2002. Nearby exploratory
borings and pit by Chen & Associates (1983) encountered similar subsurface conditions.
In our opinion, the proposed expansion to the existing facility is feasible based on
geotechnical considerations. The recommendations presented in our project report
(Hepworth-Pawlak Geotechnical, Inc., 2002) are considered suitable for the planning and
Parker 303-841-7119 6 Colorado Springs 719-633-5562 9 Silverthorne 970-468-1989
Town of New Castle
c/o Schmueser Gordon Meyer
January 10, 2008
Page 2
preliminary design. When design plans have been developed, we should be contacted to
perform additional exploration and provide additional recommendations as needed.
If you have any questions or need further assistance, please call our office.
Sincerely,
HEPWORTH— PAWLAK GEOTECHNICAL, INC.
Trevor L. Knell, P.J.38469 '
°9'•.1 -14 -os <
Rev. by: SLP OrtCo_ •.....••',c��
TLK/ksw
REFERENCES
Hepworth-Pawlak Geotechnical, Inc., 2002. Subsoil Study for Foundation Design,
Proposed Headworks Building, New Castle Wastewater Treatment Plant, New
Castle, Colorado. Dated April 30, 2002, Job No. 102 122.
Chen & Associates, 1983. Soil and Foundation Investigation, Waste Water Treatment
Facilities Expansion, New Castle, Garfield County, Colorado. Dated February
11, 1983, Job No. 24,888.
Job No. 1
G&Ftech
GecPtech
I April 30, 2002
Town of New Castle
c/o Schmueser Gordon Meyer, Inc.
Attn: Chris Chen
118 West 60 Street, Suite 200
Glenwood Springs, Colorado 81601
Subject:
Hepworth-Pawlak Geotechnical, Inc.
5020 County Road 1S4
Glenwood Springs, Colorado 81601
Phone: 970.945.7988
Fax: 970-945-8454
bpgeo®bpgeoteeh.com
No. 102 122
Subsoil Study for Foundation Design, Proposed Headworks Building,
New Castle Wastewater Treatment Plant, New Castle, Colorado
Dear Mr. Chen:
As requested, Hepworth-Pawlak Geotechnical, Inc. performed a subsoil study for
design of foundations at the subject site. The study was conducted in accordance with
our agreement for geotechnical engineering services to the Town of New Castle dated
January 7, 2002. The data obtained and our recommendations based on the proposed
construction and subsurface conditions encountered are presented in this report.
Proposed Construction: The proposed headworks building will be a one-story CMU
block structure approximately 1,500 to 2,000 square feet in size and located on the site
as shown on Fig. 1. Ground floor will be slab -on -grade. Cut depths are expected to
range between about 3 to 4 feet. Foundation loadwg's"are assumed to be relatively light
and typical of the proposed type of construction.
If building conditions or foundation loadings are significantly different from those -
described above, we should be notified to re-evaluate the recommendations presented in
this report.
(qsS 60)
Site Conditions: The site is currently occupied by the Town of New Castle's
wastewater treatment plant with existing metal buildings and treatment facilities as
shown of Fig. 1. The Union Pacific Railroad right-of-way borders the site to the north
and the Interstate 70 right-of-way creates the southern boundary of the site. Site
grading from prior development has resulted in fill being placed over much of the area.
The ground surface is relatively flat with a gentle slope down to the south. Elk Creek
is located to the west and the Colorado River is located just to the south of Interstate 70.
Rounded cobbles were visible on the ground surface throughout the site.
Town of New Castle
April 30, 2002
Page 2
Subsurface Conditions: The subsurface conditions at the site were evaluated by
excavating two exploratory pits at the approximate locations shown on Fig. 1.
Underground pipes prevented exploration in the western part of the proposed building
area. The logs of the pits are presented on Fig. 2. The subsoils encountered, below up
to about 3 1/2 feet of gravelly fill materials, consist of relatively dense, sandy silty
gravel with cobbles and boulders to the maximum explored depth of 7 feet. A thin
layer of stiff sandy silt was encountered between the fill and natural granular soils at Pit
1. Results of a swell -consolidation test performed on a relatively undisturbed sample of
the sandy silt, presented on Fig. 3, indicate moderate to high compressibility under light
loading and a minor collapse potential (settlement under a constant load) when wetted.
Results of a gradation analysis performed on a sample of sandy silty gravel with cobbles
(minus 5 inch fraction) obtained from Pit 1 are presented on Fig. 4. Free water was
observed in the pits at depths of 5 1/z and 7 feet below the ground surface at the time of
excavation. The soils above the water level were moist. Nearby borings previously
drilled by Chen & Associates (1983) encountered similar subsurface profiles to the
current study pits.
Foundation Recommendations: Considering the subsoil conditions encountered in the
exploratory pits and the nature of the proposed construction, we recommend spread
footings placed on the undisturbed natural coarse granular soil designed for an
allowable soil bearing pressure of 3,000 psf for support of the proposed headworks
building. Footings should be a minimum width of 18 inches for continuous walls and
2 feet for columns. Loose and disturbed soils, existing fill and compressible silt solls
should be completely removed from the building area to expose the undisturbed natural
coarse granular soils. Excavation cut depths should be kept relatively shallow in order
to prevent construction below the water level. Exterior footings should be provided
with adequate cover above their bearing elevations for frost protection. Placement of
footings at least 36 inches below the exterior grade is typically used in this area.
Continuous foundation walls should be reinforced top and bottom to span local
anomalies such as by assuming an unsupported length of at least 12 feet. Foundation
walls acting as retaining structures, if any, should be designed to resist a lateral earth
pressure based on an equivalent fluid unit weight of at least 50 pcf for the on-site soil as
backfill, excluding debris, organics and oversized rock.
Floor Slabs: The natural coarse granular subsoils, are suitable to support lightly to
moderately loaded slab -on -grade construction. We expect that structural fill will be
needed to re-establish design subgrade level. To reduce the effects of some differential
movement, nonstructural floor slabs should be separated from all bearing walls and
columns with expansion joints which allow unrestrained vertical movement. Floor slab
Town of New Castle
April 30, 2002
Page 3
control joints should be used to reduce damage due to shrinkage cracking. The
requirements for joint spacing and slab reinforcement should be established by the
designer based on experience and the intended slab use. A minimum 4 -inch layer of
free -draining gravel should be placed beneath interior slabs to facilitate drainage. This
material should consist of minus 2 -inch aggregate with less than 50% passing the No. 4
sieve and less than 2 % passing the No. 200 sieve.
All fill materials for support of floor slabs should be compacted to at least 95 % of
maximum standard Proctor density at a moisture content near optimum. Required fill
can consist of the on-site coarse granular soils or suitable imported granular material
devoid of vegetation, topsoil and oversized rock.
Surface Drainage: The following drainage precautions should be observed during
construction and maintained at all times after the building has been completed:
1) Inundation of the foundation excavations and underslab areas should be
avoided during construction.
2) Exterior backfill should be adjusted to near optimum moisture and
compacted to at least 95 % of the maximum standard Proctor density in
pavement and slab areas and to at least 90 % of the maximum standard
Proctor density in landscape areas.
3) The ground surface surrounding the exterior of the building should be
sloped to drain away from the foundation in all directions. We
recommend a minimum slope of 6 inches in the fust 10 feet in unpaved
areas and a minimum slope of 3 inches in the fust 10 feet in pavement
and walkway areas.
4) Roof downspouts and drains should discharge well beyond the limits of
all backfill.
Limitations: This study has been conducted in accordance with generally accepted
geotechnical engineering principles and practices in this area at this time. We make no
warranty either expressed or implied. The conclusions and recommendations submitted
in this report are based upon the data obtained from the exploratory pits excavated at
the locations indicated on Fig. 1 and to the depths shown on Fig. 2, the proposed type
of construction, and our experience in the area. Our findings include interpolation and
extrapolation of the subsurface conditions identified at the exploratory pits and
variations in the subsurface conditions may not become evident until excavation is
performed. If conditions encountered during construction appear different from those
described in this report, we should be notified at once so re-evaluation of the
recommendations may be made.
Town of New Castle
April 30, 2002
Page 4
This report has been prepared for the exclusive use by our client for design purposes.
We are not responsible for technical interpretations by others of our information. As
the project evolves, we should provide continued consultation and field services during
construction to review and monitor the implementation of our recommendations, and to
verify that the recommendations have been appropriately interpreted. Significant design
changes may require additional analysis or modifications to the recommendations
presented herein. We recommend on-site observation of excavations and foundation
bearing strata and testing of structural fill by a representative of the geotechnical
engineer.
If you have any questions or if we may be of further assistance, please let us know.
Sincerely,
HEPWORTH - PAWLAK GEOTECHNICAL, INC.
Trevor L. Knell
Reviewed by:
Steven L. Pawl
TLK/ksw
attachments
cc: Schmueser Gordon Meyer, Inc. — Attn: Chris Chen
REFERENCE
Chen & Associates, 1983, Soil and Foundation Investigation, Waste Water Treatment
Facilities Expansion, New Castle, Garfield County, Colorado, Job No. 24,888
report dated February 11, 1983.
N
LEGEND:
■ PIT EXCAVATED TO ELK CREEK
FOR THIS STUDY.
0 BORING DRILLED
BY CHEN & ASSOC. APPROXIMATE SCALE
(APPROXIMATE) PROPOSED V = 60'
❑ PIT EXCAVATED a PHASE 2 CHLORINE
BY CHEN & ASSOC. BUILDING AND
UNION
JOB NO. 24,888 CONTACT TANK TO
—►
(APPROXIMATE) PIT i RAILROAD
EXISTING r- -1
CHLORINE
OBUILDING
PROPOSED L ",
PHASE 2
CLARIFIERSO O
SPUTTER
O osox
EXISTING /
CLARIFIERS PIT 1
BORING 2 0` ■
BORING 3 r 1 OLD
BO ING -J BLO
u L-
r
-
y --�62
PROPOSED EXI TING B ILD
It
PHASE 1 ( AERATION
BLOWER BASIN
o BUILDING L _ _ J
PROPOSED
PHASE i
DIGESTER
PROPOSED
PHASE 2
DIGESTER
PROPOSED
PHASE 3
DIGESTER
PROPOSED
PHASE 2
BLOWER
BUILDING
PROPOSED
PHASE 2
AERATION
BASINS
102 122 ( HEPWORTH-PAWLAK�LOCAl10N OF EXPLORATORY PITS Fig. 1
GEOTECHNICAL. INC. 9
PIT 1 PIT 2
®FILL, sandy clayey gravel with scattered cobbles, loose to medium dense, slightly moist to moist,
brown, metal debris encountered in Pit 2.
® SILT (ML); sandy, stiff, moist, brown.
GRAVEL, COBBLES and BOULDERS (GM—GP); sandy, slightly silty to silty, dense, moist above water
o` level, brown.
2" Diameter hand driven liner sample.
_ Disturbed bulk sample.
Free water level in pit at time of excavating.
NOTES:
1. Exploratory pits were excavated on April 17, 2002 with a Case 580D backhoe.
2. Locations of exploratory pits were measured approximately by pacing from features on the site plan
provided.
3. Elevations of exploratory pits were not measured and logs of exploratory pits are drown to depth.
4. The exploratory pit locations and elevations should be considered accurate only to the degree implied
by the method used.
S. The lines between materiols shown on the exploratory pit logs represent the approximate boundaries
between material types and transitions may be gradual.
6. Water level readings shown on the logs were mode at the time.and under the conditions indicated.
Fluctuations in water level may occur with time.
7. Laboratory Testing Results:
WC = Water Content ( X )
DD = Dry. Density ( pcf )
t4 = Percent retained on No. 4 sieve
—200 = Percent passing No. 200 sieve
1 702 122 1 GEOTECHNICAL,W NC. LOGS OF EXPLORATORY PITS I Fig. 2 I
0
0
y
D 87.4
M
k
—200.77
5
I .
J 2400-1$ Ir�•
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11.
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10
LEGEND: '
®FILL, sandy clayey gravel with scattered cobbles, loose to medium dense, slightly moist to moist,
brown, metal debris encountered in Pit 2.
® SILT (ML); sandy, stiff, moist, brown.
GRAVEL, COBBLES and BOULDERS (GM—GP); sandy, slightly silty to silty, dense, moist above water
o` level, brown.
2" Diameter hand driven liner sample.
_ Disturbed bulk sample.
Free water level in pit at time of excavating.
NOTES:
1. Exploratory pits were excavated on April 17, 2002 with a Case 580D backhoe.
2. Locations of exploratory pits were measured approximately by pacing from features on the site plan
provided.
3. Elevations of exploratory pits were not measured and logs of exploratory pits are drown to depth.
4. The exploratory pit locations and elevations should be considered accurate only to the degree implied
by the method used.
S. The lines between materiols shown on the exploratory pit logs represent the approximate boundaries
between material types and transitions may be gradual.
6. Water level readings shown on the logs were mode at the time.and under the conditions indicated.
Fluctuations in water level may occur with time.
7. Laboratory Testing Results:
WC = Water Content ( X )
DD = Dry. Density ( pcf )
t4 = Percent retained on No. 4 sieve
—200 = Percent passing No. 200 sieve
1 702 122 1 GEOTECHNICAL,W NC. LOGS OF EXPLORATORY PITS I Fig. 2 I
I
be 2
O
3
4
8
11
0.1 1.0 10 100
APPUED PRESSURE — ksf
102 122 HEPWORTH—PAWLAK SWELL CONSOLIDATION TEST RESULTS FIg.. 3
GEOTECHNICAL, INC.
Moisture Content 29.4 percent
Dry Density 87 pof
—200 a 77 percent
Somple of Sondy Silt
From: Pit I ot .3 Feet
imu
nmi■�
mi
u■nii
�,111IN
■�nn�
■alum
�
■iiiii
n�
0.1 1.0 10 100
APPUED PRESSURE — ksf
102 122 HEPWORTH—PAWLAK SWELL CONSOLIDATION TEST RESULTS FIg.. 3
GEOTECHNICAL, INC.
u
SECTION 22
GEO-TECHNICAL INFORMATION
22.1 GENERAL
The Geo -Technical Report prepared by Chen and Associates, which is an evaluation
of the soil characteristics at the treatment plait 'site,`is included in this :._..
section. The following on-site test work was done for this report:
1. Five (5) testholes were drilled and drill loge were recorded for
each testhold. Samples were taken from each of the testholes for
laboratory analysis.
2. One backhoe pit was dug and samples taken..
Location of the testholes and backhoe pit are shown on Figure 1 of the
Geo -Technical Report.
22.2 TREATMENT PLANT CONSTRUCTION SITE CONDITIONS
Information on the treatment plant site soil conditions is found on pages 5 through
7, conclusions are given on page 4, and recommendations on. pages 7 through iL
In general, it is anticipated that the existing subsoil conditions will be suitable
for the proposed new structures, using standard spread footing construction. It
is also anticipated that the naturally existing subsoils are suitable for construc-
tion of the proposed flood control embankment., .
22-1
TABLE OF CONTENTS
CONCLUSIONS
SCOPE
PROPOSED CONSTRUCTION
SITE CONDITIONS
SUBSOIL CONDITIONS
DESIGN RECOMENDATIONS
Building Foundation
Flood Control Embankment
Floor Slabs
Surface Drainage
LIMITATIONS S
FIGURE 3 - LOCAT.ION OF EXPLORATORY,HOLES.AND.PIT
FIGURE 2'- LOGS OF.EXPLORATORY.HOLES.AND PIT
FIGURE 3 LEGEND AND NOTES
FIGURES 4, 5 6 AND.: 7. -.GRADATION. TEST RESULTS
TABLE I - SUMMARY OF LABORATORY TEST RESULTS
22-3
0
CONCLUSIONS
1) The subsoils encountered across the site were relatively uniform
and consisted of a variable depth of man -placed fill overlying
natural silty sands, gravels, cobbles and boulders to the maximum
depth explored, 20 feet. Free ground water was encountered in moe
areas and varied in depth from 3 feet to 7'h feet *elow the ground
surface.
2) The clarifier tank, metal building, and manhole:for'the.sump pump
should be founded on a spread footing or mat type foundation,
designed for. a'maximum"soil: bearing pressure. of 4,000 psf. Shoris
or sloping and dewatering of the excavations for the. clarifier
and manhole will be required. Below grade':structures:should be
designed for free.ground Vater.level-near existing'ground.surface
;) Construction of the flood control earthen embankment with on-site
or import soils should be feasible with precautions and recommend
criteria as discussed herein.
22-4
0
SCOPE
This report presents the results of a soil and%foundation. investigation.
conducted for the proposed' wastewater treatment facilities expansion to
be located within the Town of ,New Castle, Garfield:,County, Colorado.
The report presents a discussion•of the subsoil conditions encountered,
recommended foundation types, allowable' bearing pressures;embankment
design criteria and other soil related design and construction consider-
ations.
The field and laboratory'. studies havebeen conducted. in general
accordance with our proposal to. Westwater Engineering dated.December 29,
1982.
PROPOSED CONSTRUCTION
The proposed construction will.consist.of the following%structures:
1) A buried clarifier .tank, 25 feet in. diameter. and .15 feet.in height
with cast -in-place concrete .floor and walls:` . ..
2) A manhole, about 15 feet deep in depth.,, to -be used as.a sump pump:
3) A small metal building which will, house plant air blowers, (the
floor level is expected to be near existing. grade): and.'.
4) An earthen flood.control embankment, about .7: to 8 feet maximum
height. to be constructed, parallel to Elk .Creek. The berm will tie
into the existing railroad and 1-70 .embankment.
Foundation, loadings for the proposed tanks and blower building are
assumed to be relatively light to moderate.': If.. the scope. of. the proposed
project change's significantly from that described:. this office should be
notified for re -evaluation -of the recommendations presented herein.
22-5
SITE CONDITIONS
The. site of the proposed facilities. is presently developed and occu
by :concrete tanks;:ponds, buried. pipelines and.access;drives (refer to
.Fig. Ij. Topographically, the area:is relatively flat.with a -very
.slight grade down:to.the.south and west: :Previous_ site grading and land
use has. resulted in fill being placed .over much of.the area. .Fill piles
northwest of the existing treatment building and west of the existing
concrete tank appeared to be'consisted-of miscellaneous.. waste. No natty
drainages cross the site, .however, Elk: Creek. is.located;immediately to
the west. Some cutting and fill has been performed mainly for the exia
pond which is about 5 to 6 feet deep. Vegetative cover across the
site consisted essentially of weeds, scattered deciduous trees, and so=
moderatley=thick stands of.brush....: The..bottom of...the longer dry pond waa
marshy and partially covered with cattails.. Approximately 10 feet of
elevation difference exists.between.the main facility construction area
and the elevation of Elk Creek. .
SUBSOIL CONDITIONS .
The subsoil conditions were. investigated by. drilling five explorat
holes and by observing one backhoe .excavated.pit. The holes and pit war
located within or.near each construction site; as. indicated on the
attached *Fig. I. ..Graphic logs of the subsoil profile encountered are
presented on Fig. 2. ..As indicated. -the. profile:,was .relatively uniform
and consist �'of.about I to 4'h ,feet.o£:man-placed,.fill overlying an all
deposit of silty sands,.. -gravels, cobbles. and small boulders.,. The fill
material was composed.of mixed sands,. gravels, cobbles and some
22-6
miscellaneous debris (asphalt and concrete pieces). Because of. erratic
composition, this: material should not be used for support of structures
in its present condition. The underlying natural gravels. contained
infrequent clayey sand lenses or layers.,.bue in general were dense.
Practical drill rig refusal. occurred at all, of the test holes due to
material size and relative. density..,,
Free ground water was encountered at.most hole. locations and varied
from about.3.to.7k feet below the ground. surface. at the time of
drilling and when checked 1 day later. Slotted PVC. pipe was installed in
some of the holes for future water level readings. Variation will
likely occur with sea,sonal fluctuations in the.Colorado River and Elk
Creek flow. At times of prolonged or maximum„flooding, rise of free
water level to near ground surface may be possible.
Gradation analyses performed on the minus 3/4 inch.to 5 inch fraction
of the natural.. gravels and existing fill are presented on the. attached .
Figures 4, 5, and 6. A gradation analysis was also, conducted' on proposed
embankment fill material (import borrow) and is presented on Fig. 7. A
summary of laboratory tests results is presented on Table I.
DESIGN RECOMHENDATIONS .
Building Foundation: The subsoil profile within the proposed clarifier
tank, manhole and building locations consist primarily of man -placed fill
overlying natural sands, gravels and cobbles. A spread footing or mat type
.foundation placed on the natural granular. deposit should be suitable for
.support. Settlements should be tolerable and. essentially occur during
.construction. The following design and construction criteria should be
observed for this type_of foundation:
22-7.
1) Footings or tank mat should'be placed'on the undisturbed natural
granular subsoils beneath all topsoil, disturbed soils or existing
fill and designed for a maximum bearing pressure of 4,000 psf
(including weight of "tank fluid).'
2) Spread footings should have'"a'minimum dimension of 14 'inches for
walls and 24 inches for column's.
3) Continuous foundation walls should be reinforced to span an unsupp
length of at least 10 feet in the event -of some differential movem
4) Below grade walls acting as retaining structures should be designs
to resist lateral eprth pressures based on an' equilivertt fluid
weight of 40 pcf above the maximum expected water level and 80 pcf
for a submerged condition. The below grade structures (tank and
manhole) should also be designed -for resulting hydrostatic uplift
pressures.
5) Exterior footings should be provided with 'soil: "cover above their
bearing elevations for frost protection.
6) ' Foundation excavations should be observed by'a representative of
the soil 'engineer prior 'to 'concrete placement.
7) Due to the potential for ground water fluctuation, backfill
around the tank and manhole should consist of free draining gravel
material having a maximum 3 inch size and'less'than 5 percent
passing the No. 200 sieve.
8) Considering the granular subsoils and high groundwater level,
shoring or sloping of the excavation faces for the clarifier and
manhole will be required.•'Shoring of'confined excavations such a
for the manhole may consist of soldier'beams and timber lagging i
conjunction with lateral bracing top to bottom. Where the excava
is sloped, a grade cf 1:1 (horizontal to vertical) or flatter
should be anticipated.
22-8
9) Dewatering will. be required during construction of the clarifier
and manhole at proposed excavation depths. Shallow drawdown, probably
up to 10,.feet, may be- possible with sump .pumps within the excavation.
However, in fine non -cohesive soils, boiling.or:a quick condition
can develop. at the excavation bottom.as.a result of seepage forces. A
perimeter. well system would reduce or prevent this potential and also
allow steeper, dry excavation. slope faces.
Flood Control Embankment: Construction of the proposed.flood control
earthen embankment on the natural existing sub,soils.should befeasible
frpm.a geotechnical consideration. The following design,and construction
criteria are recommended:
1) Within the embankment.fill.area, the ground surface should be
cleared. of all vegetation,,topsoil aud.existing fill. The exposed
surface should be scarified,,moistened and compacted to a minimum
90% standard Proctor density at,a.moisture content.neax optimum.
2) Embankment fill material.should be placed in uniform lifts and
compacted to at least 95% standard Proctor density at.a moisture
content near optimum. Required fill may consist of on-site soils
or existing fill provided.ogersized rock, vegetation, topsoil and
debris is removed prior to fill placement.. Imported sandy gravelly
clays similar to those sampled for this study may also be used.
3) Based on the above conditions, embankment, and, fIll slopes constructed
on a.2:1.(horizontal to vertical) grade or flatter. should have
adequate safety against failure. This assumes the use of on-site
relatively free draining granular soils and a relatively dry slope,
not subjected to seepage forces. Some slumping of saturated sandy
or silty..zones could occur if subjected. to rapid draw down. A
flattened slope on the.order of 3:1 would reduce this potential.
Fine grained soils such -as those proposed ,for borrow used in construction
22-9
of the embankment should have a final grade no steeper than 3:1 on
the stream or flood side and 2:1 on the non -flood side.
4) Slopes should be adequately protected to reduce the potential for
erosion.
5) Site preparation and fill placement should be performed with obser
and'testing bya representative of the soil engineer to verify
compliance with recommended specifications.
Fioor Slabs- The natural granular soils are capable of supporting
lightly loaded floor slabs. To reduce damage due to slight differentia
movement, the slabs should be provided with control joints, be adequate
reinforced, and be separated from bearing'walls with a positive expansi
joint.A gravel'levelling course may be used to provide a uniform
surface for concrete placement. Required fill beneath floor slabs
should be non -expansive granular soils compacted to'a minimum 95% stanc
Proctor density. The on-site natural sands and gravels and existing
fill 'are suitable for use provided' oversized rock, topsoil and debris
removed prior to'placement.
Surface Drainaae: The following drainage precautions should be observt
during construction and maintained at all times after the structures h
been completed:
(1) Inundation of foundation excavations should be avoided during
construction.
(2)' Miscellaneous backfill 'Around the buildings' and structures should
be moistened and compacted.to at least 90% of standard Proctor
density.
(3) The ground surface surrounding the exterloi of end buildings or
structures' should be sloped to drain away In all directions.
(4) Roof downspouts and drains should discharge well beyond the limit
of all backfill.
22-10
LIMITATIONS
This report has been prepared in accordance with generally accepted
soil and foundation engineering practices in this area for the use by
the client for design purposes. The conclusions and recommendations
submitted in this report are based upon the data obtained from the test
holes drilled and pit excavated at the locations indicated on Figure 1.
The nature and extent of variations between the test locations may not
become evident until excavation is performed. If during construction,
soil and ground water conditions appear to be different from those
described herein, this office should be advised at once so that re-
evaluation of the recommendations may be made. We recommend on-site
observation of excavations and foundation bearing strata by a soil
engineer.
RJV/ko
CHEN AND ASSOCIATES, INC.
By
Ronald J.asqu .E.
Reviewed Ey
Steven L. Pawiak, P.H.
22-11
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LEGEND;
Silty to .clayey sand; gravel and cobble fill, some._mixed organics
and debris, moist, dark.brown:
Sand,.(SAl), silty with scattered gravels or cobbles, ,Ioose.to medium
• dense, very moist ;.brown.
Sand., ;Gravel and Cobbles (GM),'.'silty. with infrequent: clayey sand lenses,
' some boulders, *rounded gravels, dense, moist to wet,brown.
Standard Penetration Test.Sample.ASTM D-1586; the symbol 36/12 indicates
that 36. blows of -a-140 lb. hammer falling 30 inches were required to
drive the sampler 12 inches.
r' Disturbed.Bulk Sample
Yi
® Indicates P.V.C. pipe installed in hole to depth shown.
0,1 Indicates depth to free water at time of drilling 6.number of days 'after
'T drilling measurement was taken.
Depth at which hole caved. .
Practical Rig Refusal.
NOTES: .
1) Holes:were drilled:on.February 8, 1.983, with.a 4 -inch diameter .
continuous flight, power auger.. "
Backhoe pit was excavated by',ciient on February 8,.,1983.
2) Elevations are approximate and were estimated from contours.on.plan
provided by client.
5) }VC-:,' lister Content (�);
-200 = Percent -'Passing No. 200: Sieve;. "
NP = Non Plastic.
24,888Legend and Notes
cben and associates, ine. fl�
CA -2.79
chen and associates, inc.
1 DIAMETER OF PARTICLE IN MILLIMETERS 1
CLAY TO SILT SANO A•EL
FINE �dEJWM CJAT.S=. =SNE CO;
GRAVEL 27% SAND S4 % SILT AND CLAY. 19+. .
LIOVIO LIMIT % PLASTICITY INDEX
SAMPLEOF silty gravelly sand FROM Hole 1 at 14'
SArJO GFA+EI
CLAY TO SILT =� MEOIUM CORPSE =RNs OOAPSE COE9LES
GRAVEL 4S% SAND 33 % SILT AND CLAY 22 *I
LIOVIO LIMIT % PLASTICITY INDEY
SAMPLE -0 silty sand S gravel FROM Hole 2 at lh'
'4'$$a 4
GRADATION TEST RESULTS Fig...
99.TS
chen and associates, inc.
DIAMETER OF PARTICLE IN MILLIMETERS I
CLAY TO SILT E_
CCaeEE :pry 'ac
GRAVEL 33 'a SAND 37% SIL' AND C.Av 301•
• LIOUIO LIMIT � PLASTICITY INDEX
NP "
SAMPLEOF Silty sand & gravel fill FROM Pit i at 11-4a
GRAVEL 80 *. SAND 18 % SILT AND CLAY 2%
LIOUID LIMIT 1ft PLASTICITY INDEX h
SAMPLEOF sandy gravel FROM .Pit 1 at 61-81
?4,888 6
GRADATION TEST RESULTS Fig__
22-17
ig._.—.-
22-17
CA -2-79'
chen and associates, inc.
DIAMETER OF PARTICLE IN MILLNITERS
CLAY TO SILT — 54E` COBBLE£
r F•NE k:EONed CAFSE •.�E C:cASE
GRAVEL 52 1 SAND 19 'A S0.' AND CLAY 49%
UDUID LIMIT 26 •' PLASTICITY 1.400 10
SAMPLEOF sandy gravelly. clay. FROM imported
CLAY TO SILT
GRAVEL +4
uGU10 LIMIT
SAMPLE OF
24,888
DIAMETER OF PARTICLE IN MILLIIJETERS
$ANO•' I&AVE
Me •�EOiVIr IrOAPS1 +••II Lw
SAND % SILT AND CLAY �.
6. ?LASTICITV nay �T .
FCr,..
GRADATION TEST RESULTS
22-18
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