United States Region Vlll
Environmental Protection 1860 Lincoln Street
Agency Denver, Colorado 80295
Solid Waste
3€PA A TECHNICAL
ASSISTANCE
PROGRAM REPORT
PAGOSA SPRINGS
LANDFILL EVALUATION
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A TECHNICAL ASSISTANCE PANELS PROGRAM REPORT:
PA60SA SPRINGS
LANDFILL EVALUATION
Prepared For:
U.S. Environmental Protection Agency
Region VIII
1860 Lincoln Street
Denver, Colorado 80295
Prepared by:
Fred C. Hart Associates, Inc.
Market Center
1320 17th Street
Denver, Colorado 80202
January, 1982
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PAGOSA SPRINGS LANDFILL EVALUATION
ENVIRONMENTAL PROTECTION AGENCY REGION VIII
AQOSA SPRINGS
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Public Law 94-580 - October 21, 1976
Technical assistance by personnel teams. 42 USC 6913
RESOURCE RECOVERY AND CONSERVATION PANELS
SEC. 2003. The Administrator sha?1 provide teams of personnel, including
Federal, State, and local employees *or ^contractors (hereinafter referred to as
"Resource Conservation and Recovery Panels") to provide States and local gov-
ernments upon request with technical assistance on solid waste management,
resource recovery, and resource conservation. Such teams shall include techni-
cal, marketing, financial, and institutional specialists, and the services of
such teams shall be provided without charge to States or local governments.
This report has been reviewed by the Project
Officer, EPA, and approved for publication.
Approval does not signify that the contents
necessarily reflect the views and policies of
the Environmental Protection Agency, nor does
mention of trade names or commercial products
constitute endorsement or recommendation for
use.
Project Officer: William Rothenmeyer
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TABLE OF CONTENTS
Page
LIST OF TABLES v
LIST OF FIGURES vi
I. EXECUTIVE SUMMARY 1
II. DESCRIPTION OF STUDY AREA
A. Introduction 3
B. Location 3
C. Population 4
D. Economy 8
E. Climate 9
F. Geology/Soils 11
III. PAGOSA SPRINGS LANDFILL EVALUATION
A. Introduction 17
B. Identification of Deficiencies 18
C. Upgrading Strategy 26
D. Estimated Life of Landfill 34
E. Landfill Operational Plan 39
F. Methodology For Implementing Proposed Plan 42
G. Review and Comment on User Charge System 44
IV. MILL CREEK SITE EVALUATION
A. Introduction 48
B. Surface Water 50
C. Hydrogeology 51
D. Other Environmental Constraints 51
E. Availability and Suitability of Cover Material .. 52
iii
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TABLE OF CONTENTS (Continued)
F. Land Area 53
G. Estimated Costs 57
H. Accessibility 61
REFERENCES 62
APPENDIX A
Soil Maps A-l
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LIST OF TABLES
Table Title Page
1 Historical & Projected Population Data 7
2 Archuleta County Housing Data, 1978 8
3 Assessed Valuation of Archuleta County, 1979 9
4 Mean Monthly Precipitation and
Evapotranspiration Data 11
5 Soil Survey Interpretations 14
6 Monthly Water Balance Analysis 21
7 Well Inventory, Pagosa Springs Area 24
8 Pagosa Springs Landfill Upgrading Costs 33
9 Estimated Available Landfill Capacity (Refuse) 37
10 Estimated Volume of Cover Material 38
11 Pagosa Springs Annual Landfill Operations Cost 41
12 Frequency of Customer Use at Pagosa Springs Landfill ... 45
13 Site Development Costs (Mill Creek Site) 58
14 Mill Creek Landfill Costs 60
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LIST OF FIGURES
Figure Title Page
1 Topographic Map, Pagosa Springs Area 5
2 Geologic Map, Pagosa Springs Area 6
3 Cross Section through the Pagosa Springs Area, Colorado 13
4 Suitability of Soils for Landfill Operation 19
5 Elevation of the Potentiometric Surface, Dakota Sandstone 23
6 Potential Borrow Site Locations 28
7 Schematic of Landfill Cells 36
8 Mill Creek Site Location 49
9 Trench and Area Methods of Sanitary Landfill ing 56
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I. EXECUTIVE SUMMARY
The County's present population is served by a seven acre landfill situated
near Pagosa Springs. Based on projected population figures (5,618 County
residents by 1985) and a waste generation rate of 4.0 pounds per capita per day,
it is calculated that eleven tons of waste per day (or 10,250 cubic yards of
compacted waste per year) will be generated by the community. The estimated
remaining life of the landfill is five years.
The primary concern to be addressed in order to ensure the environmental
and esthetic integrity of the disposal site is the locating of sufficient quan-
tity of soil that is suitable for cover material. Six potential borrow sites
are designated that are: 1) in areas developed on Yawdim clay loam or Work
loam, and; 2) within three or four miles of the landfill.
Hydrologic concerns at the landfill center on the recommended construction
of diversion ditches to control run-on, leachate formation, contaminated run-
off, and erosion. The report recommends that detailed groundwater monitoring
not be initiated at this time, as minimal precipitation and rapid run-off limit
leachate formation and the associated possibility of ground water contamination.
The upgrading strategy proposed for the landfill requires the following
actions: 1) acquisition of sufficient suitable cover material; 2) upgrading of
the present access road; 3) construction of a diversion ditch to control surface
water flow; 4) construction of a gatehouse, and; 5) construction of a peripheral
fence to control access and windblown debris. The total estimated cost of
upgrading the Pagosa Springs landfill is $43,600.
A reconnaissance study of the Mill Creek area (2 1/2 miles east of Pagosa
Springs) is also presented in this report. Preliminary investigations indicate
that Mill Creek may prove suitable for landfill operations when the facility at
Pagosa Springs reaches capacity (i.e., 1985). Favorable characteristics at Mill
Creek include: 1) proximity to user population; 2) suitable topography and
geology; 3) ready access via existing roads; 4) State ownership, and; 5) current
non-intensive land use.
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It is calculated that, if developed and operated properly, a landfill at
Mill Creek will meet the requirements of the community for twenty-five years.
The Mill Creek site development costs (exclusive of land purchase) are estimated
to be $45,300.
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II. DESCRIPTION OF STUDY AREA
A. Introduction
In the Resource Conservation and Recovery Act (RCRA) Congress gave the
Environmental Protection Agency (EPA) authority to provide local governments
with technical assistance on solid waste management. Using this authority, EPA
Region VIII provided consultant assistance to evaluate the landfill at the Town
of Pagosa Springs, Archuleta County, Colorado. This service is referred to as
"Resource Conservation and Recovery Panels" assistance.
The scope of work for this evaluation includes an analysis of the defi-
ciencies of the current landfill, the feasibility of upgrading the site to
comply with RCRA regulations, provision of an operations plan, and initial study
of the Mill Creek site as a location for another landfill, given the cover
material and land constraints of the current site.
B. Location
The Town of Pagosa Springs is situated on the San Juan River in south-
western Colorado. It is about 30 miles north of the New Mexico boundary via
U.S. Highway 84 and lies 25 miles west of the Continental Divide on U.S. High-
way 160 (see Figure 1). The Town's landfill is two miles south of Highway 160
on the Trujillo Road in Section 26, R2W, T35N. Figure 2 is a portion of a
geologic map of the Pagosa Springs area1. The list below explains the geologic
symbols used in Figure 2.
Geologic Symbol Explanation
Qal - Alluvium
Qt - Terrace Deposits
Qtr - Travertine Deposits (calcium carbonate
deposited by hot springs)
Source: Reference 12.
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Ti - Dikes
Kmu - Mancos Shale (upper member)
Km! - Mancos Shale (lower member)
Kd - Dakota Sandstone
C. Population
The Town of Pagosa Springs is the county seat of Archuleta County. The
current population of the County is estimated by the County Planning Office to
be approximately 4,235. This includes the Town's, population of about 1,500.
Historical and projected population data are shown in Table 1. (The Chief of
the Planning Office, Mr. Ebeling, estimates that 85 percent of the County's
residents live within 10 miles of Pagosa Springs). The "Plan for Progress", a
master planning document for the Town2, also indicates that about 80 percent
(973 of 1222 units) of the County's year-round housing is located in the
vicinity of the Town, i.e. the northeastern part of the County, as indicated in
Table 2.
Therefore, the growth in this area warrants particular attention to the
long-term solid waste needs of the community.
Source: Reference 1.
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. U^L-A^-.^. -v .».'"*
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1 MILE
FIGURE 2.
GEOLOGIC MAP, PAGOSA SPRINGS AREA
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TABLE 1
POPULATION DATA
HISTORICAL AND PROJECTED*
Year
Archuleta County
Town of Pagosa Springs
1890
1900
1910
1920
1930
1940
1950
1960
1970
1975
1977
1980
1985
1990
1995
2000
826
2,117
3,302
3,590
3,204
3,806
3,030
2,629
2,733
3,000b
3,594d
4,014b
5,325b
6,642b
7 ,813b
9,000b
!4,325)
;5,618)
7,007)
;8,243)
,9,500)
669
1,032
804
1,591
1,379
1,374
1,360
l,40(?c
l,3*82d
1,600C
1.625C
1,750C
1,875C
2,500C
Source: Archuleta County Planning Office.
Estimated by county planning office. The lower figures are
based on 1975 estimates. The higher figures in parentheses
are adjusted based upon 1977 census data.
From "Land Use Inventory and Preliminary Land Use Plan for
Pagosa Springs" by Carl S. Becker Company, 1975. Subsequent
data indicates these projections to be too high for the Town
itself.
Special Census taken
1977.
by the U.S. Bureau of the Census, June,
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Total Living Units
TABLE 2
ARCHULETA COUNTY HOUSING DATA - 1978
Pagosa Northeast Remaining Total
Springs County^ Countyb County
511
1,267
528 1,795
Year-Round
467
973
249 1,222
Seasonal or Part-Time
21
216
265 481
Unknown
23
78
14
93
a Includes Town of Pagosa Springs.
b Includes Blanco, Chromo, Trujillo, Pagosa Junction, Arboles and Chimney
Rock Districts.
D. Economy
Personal incomes in the county are low compared with the State as a whole.
The U.S. Bureau of the Census, County and City Data Book, 1977 reports the 1974
per capita personal income in the County at $3,390 compared to $4,884 in the
State of Colorado.
The Town master planning report concludes that the unemployment rate has
consistently been higher than that of the State as a whole. The report sum-
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marizes the unemployment statistics since 1970, and portrays a 21.2 percent
unemployment for the Town (versus 5.5 percent for the State) in 1978.
Table 3 was provided by the County Planning Office and shows the tax base
for the County in 1979. About two-thirds of the County's assessed valuation
comes from residential properties. This high proportion of residential property
valuation contrasts with a relatively low commercial and industrial tax base.
TABLE 3a
ASSESSED VALUATION OF ARCHULETA COUNTY - 1979
Residential $20.0 million
Commercial 3.0 million
Industrial 0.7 million
Agricultural 3.2 million
Natural Resources 0.9 million
a Source: Archuleta County Planning Office.
E. Climate
The average annual precipitation is 18.74 inches at Pagosa Springs. Minimum
monthly precipitation generally occurs in June, and maximum monthly
precipitation in August. (The period of record is 400 months.) Precipitation
averages in the mountains are considerably higher with a few locations in the
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County estimated to average 50 inches per year. Most of the increase in preci-
pitation from the valley to the mountains occurs in mid-winter, when the moun-
tains receive more snowfall. Average snowfall measurements are 104 inches per
year at Pagosa Springs. The mean maximum temperature varies from 38.2° F in
January to 83.5° F in July while the mean minimum varies from 1.3°F in January
to 45.3°F in July.
Table 4 is a comparison of average monthly Pagosa Springs precipitation and
evapotranspiation at Vallecito Reservoir (30 miles west of Pagosa Springs).
Evapotranspiration, the combined evaporation from the plant and soil surfaces
and transpiration from plants, represents the transport of water from the earth
back to the atmosphere. Evapotranspiration approximately equals lake evapora-
tion. 3 The evaporation is insignificant during winter months and is reported at
0 inches. At Vallecito Reservoir evapotranspiration equals 25.57 inches per
year. (Evapotranspiration was calculated according to the method given in
Thornthwaite and Mather).4 (The elevation of the Pagosa Springs landfill is
7,331 feet; the reservoir elevation is 7,665 feet ).
The climate, therefore, is relatively arid with wide seasonal precipitation
and temperature fluctuations. In the winter, precipitation is greatest and
evaporation is insignificant. Potential percolation, runoff, and run-on must be
evaluated with this in mind. All climate data are from the Colorado Climatol-
ogist, Department of Atmospheric Science, Colorado State University and were
provided for this report by William A. Ray, Jr., Pagosa Springs Town Manager.
^Source: Reference 8.
^Source: Reference 13.
10
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TABLE 4
MEAN MONTHLY PRECIPITATION AND
EVAPOTRANSPIRATION DATA
Pagosa Springs
Precipitation
(inches)
Vallecito Reservoir
Evapotranspiration
(inches)
January
February
March
April
May
June
July
August
September
October
November
December
TOTAL
1.76
1.14
1.34
1.32
1.04
.93
1.59
2.34
1.77
2.29
1.25
1.96
18.74
0.00
0.00
0.00
2.81
3.89
4.68
4.71
4.09
3.21
2.18
0.00
0.00
25.57
F. Geology/Soils
The Pagosa Springs landfill is situated on Dakota Sandstone (geologic map
symbol Kd), a quartz sandstone with some dark carbonaceous shale. Figure 3
shows a geologic cross-section through the Pagosa Springs area^. The soil
formed on the Dakota Sandstone in this area is the Valto stony loam, a shallow,
highly permeable (2.0 - 6.0 inches per hour) soil. The Soil Conservation
Service (SCS) symbol for the Valto stony loam is Ml-CE. Table 5 represents the
SCS intepretation sheet for the Ml-CE soil.
Source: Reference 7.
11
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In the vicinity of the Town of Pagosa Springs, the Mancos Shale (geologic
symbol Km) also predominates the surficial geology. To a large extent, the soil
formed on the Mancos is the Yawdim clay loam and clay (SCS symbol CO-CE), a
shallow soil exhibiting low permeability (.02-.6 inches per hour). The Work
loam and clay loam soil (SCS symbol C2-CD) that formed from shale outwash in the
area also occurs in the vicinity of Mancos shale soils. This is a slowly to
moderately permeable soil (.2 - 2.0 inches/hour in the first 8 inches and .2-.6
inches per hour below 8 inches). (See Table 5 for soil data). The C2-CD soil
is moderately deep and well drained. Soils at the Mill Creek site (discussed in
Chapter IV) consist mainly of those derived from shale and shale outwash, i.e.
the CO-CE and C2-CD soils.
A formal soil survey for Archuleta County has not been developed by the
Soil Conservation Service. Soil maps have been prepared for some areas within
the County including the Pagosa Springs landfill area and the Mill Creek site.
The quality of these maps precludes adequate reproduction; therefore, these maps
are included in Appendix A. The information regarding the Valto stony loam soil
on the Pagosa Springs landfill site and the Yawdim and Work loam at the Mill
Creek site was derived from these maps and conversations with the local SCS
office.
12
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?K>0-
•MMT
GJ
EXPLANATION
Qa — Alluvium, Quaternary
Qt — Travertin*, Quaternary
Kmu - Mancoa Shale (upper|, Upper Cretaceoue
Kml — Mancoa Shale I lower I, Upper Cralacaoua
Kd - Dakota Sandilone, Upper Cretaceoua
Jm — Morrison Formation, Upper Juraaalc
Jw — Wanaka Formation, Upper Juraaalc
Ja — Entrada' Formation, Upper Juraaalo
Hd — Dolores Formation, Upper Trlasalc
p€c — Crystalline Rocka, Precambirlan
Index Map
Figure 3. Cross Section through the Pagosa Spring* Area, Colorado
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TABLE 5
SOIL SURVEY INTERPRETATIONS
Ml-CE Valto stony loam, 3 io 2S percent slopes. TMs unit contVsls of shallot. v*i}\
dv-Bltysa'Sbt ,J5" *>"(.« ZLT"1h'c>ies detp ov«r sandstone. The soil Is pre> -it. r>AN Civ ^
AASHO
•
AJ|
•
COAKJB
PMACT.
> UN.
20-*K>
PEMCENTACC. LtSS THAN J INCHES
PASSING SIEVE NO
4
^•ss
13
30-90
40
\S-6o
MO
35- 5P
LL
?P-30
-
P:
0-5
SfL"V,v
i- •.-,
i.o-6.o
AVAILABLE
MATEM
CAPACITr
(In In)
.oa-.,o
SOIL
REACTION
f.N.
fc.6-7.^
SM.INITT
1 fi^C M lO
•!«:•
—
SHRINK-
WELL
POTENTIAL
u™
POTENTIAL
FROST
ACTION
lau,
0 2D Inches FLOOD MAZAKO ^on^
^^^ HVDROLOu'C iHOuP Q
SUITABILITY AND M-^JOI FEATURES AFFECTING SOIL AS RESOURCE MATERIAL
ar fc
SAh
T
QQT -
- oo
f'coc""-
DEGREE OF LIMITATION AND MAJOR SOIL FEATURtS AFFECTING SELECTED USE
LOCAL MOAOS AND STREf.lS
to todrock
to
SHALLOW EXCAVATIONS
»A(.l . Ai.OO.1
>' to
DWELLINGS'
..SCiiATEO STEEL
MttNVOIft AMEA.
- r.ONCHf TE
Low
MW^VOl* EH«AM«HKMT:
. .* * . ,
Shallow to bedrock
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TABLE 5 (Cont.)
CO-CC AWP I
Y
d
clay
SOIL SURVEY INTERPRETATIONS
>n* c]ay» 3 tc ?5 percent slopes. T»-lr. unit co-:;'rh.; :-.?' •« • -V
NL«A=
colored, shaje*, wsll drs I --::•* soil overlying tyineos and lewis shale at depth* of a* fo
20 Inches. Th« surface and subsoil are clay Ion* or clay. Because of the billy t»poyrnnhy,
there are inclusions of about .15 percent outcrop* of £nal ) U4.
0-10
PERCENTAGE LtSS THAN 1 INCHED
PAttiNC SIEVE NO —
4
100
10
100
•M
90-
100
TOO
70-
eo
LL
30-YO
PI
15-30
PERMEA-
BILITY
lin.-h'l
.02-. 6
•
AVAILABLE
CAPAClTV
(In. •i)
n- 1O
• • y
REACTION
(PHI
7,'i-B.i
MLiNrrv
(«C« I91
nrci
—
SWtLI.
POTCNTIAL
H^a^i
POTENTIAL
FROST
ACTION
lew
DEPTH TO ft . ' - ' ' -IAFOPAN less than 20" t"O iJ^ale. FLOOOM»ZAHO-. v/v»>
OEPTM TO SEASON ^. n'C," nATEKTABLf HtDROLOOIC GROUP
SUITABILITY AND MAJOR FEATURES AFFECTING SOIL AS RESOURCE MATERIAL
TOPSOIL
Poor -
Unsu \ 1 <
Clov le/^arn
{d - no sanfi
GRAVEL
tlnsLiltai -
HOADFILL
Pooi; - CL
pp gravel
will* PJ ovar T5 ot ^**
DEGREE OF LIMITATION AND MAJOR SOIL FE
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F4L* COO».«OtL*-ll
WORK
TABLE 5 (Cont.)
loss) and clay loam, 3 to it A slopes
SOU SURVEY INTERPRETATIONS
This unit consists of • deep, well drained soil in areas of shale •oils. The
soil is derived frost ohale outvaah. The surface 10 a dark colored loan 6 to 10"
thick. The subsoil end substrata are a clay loiuri. ffeall inclusions of soil with
shale above IjO" sore common*
ESTIMATED PHYSICAL AND CHEMICAL PROPERTIES
Mi. MA:
JW
B/72
MAJOR
SOIL
HOAIZONS
iMCHESi
0-8
8-60
CLASMPICATlON
UK) A
TEXTUK6
loam or cl
clay loam
*
UNIFIED
ML or
CL
CL
AASHO
A-!i or
A-6
A-6
CO»HU
FHACT.
0-5
0-5
PtUCCNlA^i: LlSS ^MAN 1 INCHES
4
100
100
•0
1OO
100
40
85-
100
90-
100
wo
60-
80
70-
80
LL
30-
ho
30-
liO
P:
5-
20
15-
•ILITY
Mil. It.)
.2-2*0
.2-.6
AVAILABLC
i a il
7.U-O.SJ —
1 ,
DEPTH TO BEDROCK CH HAHDPAN £_ ^ FLOOD MAZAftD M/ju*
DEPTH TO SEASONAL >•«* WATEMTAIILt Moftg MVDHOLOGIC 6MOUP (J
POTtHTtAL
Mod*
High
ACTION
Lav
low
SUITAIILITY AND MAJOR FEATURES AffCCTING SOU AS RESOURCE MATEtlAl
TOPSOIL:
Fair to good - loam to clay losja
CAAWl
tlnsuited - Mo gravel
SANO:
Unsuited - No sand
*O*«MLL:
DEGREE Of LIMITATION AND MAJOR SOIL FEATURES AFFECTING SELECTED USE
LOCAL HOAOS AMD ITMIT1:
Severe -CL with PI orer 1$
JtPTlC TANK PtLTtH
Moderate- >fod«rr«Uly tloif uajin ability
(HALLOW EXCAVATIONS:
Hoderate - Clajr loaa
UOMCC LAGOOMS:
Moderate op slope* te T%
CMELLIMCt:
Severe - Hig>i shrink - svell potential
- UMCCAtfA STIfL!
Hoderat*
Hoderatelr elov peraetbilliy
COMftOUVITV - ODNCMdTI:
Low
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III. PA60SA SPRINGS LANDFILL EVALUATION
A. Introduction
State and Federal regulations governing solid waste disposal are written in
order to protect health and the environment. Solid waste disposal sites must be
designed and operated to preserve the integrity of surface and groundwater
supplies and to limit potential health problems associated with disease-
transmitting vectors. Open burning at disposal sites may result in uncontrolled
fires, air pollution, and aesthetic problems. Poorly-operated landfills that
may be characterized by blowing debris and unpleasant odors impinge upon the
aesthetic values of the community. These problems can be prevented through
proper sanitary landfill design and operation.
The Radiation and Hazardous Waste Control Division of the Colorado Depart-
ment of Health has conducted an inspection of the Pagosa Springs landfill and
has classified it as an open dump in non-compliance with the Resource Conserva-
tion and Recovery Act (RCRA) criteria. The RCRA "Criteria for Classification of
Solid Waste Disposal Facilities and Practices" Title 40 Code of Federal Regula-
tions, Part 257 (40 CFR 257) includes criteria to evaluate the impacts of solid
waste disposal on air quality, surface water quality and groundwater quality,
disease, endangered species and safety. An open dump is a facility which does
not comply with 40 CFR 257. In citing the reasons the site was classified as an
open dump, the Department of Health specifically singled out the deficiencies of
cover material and open burning and their relationship to safety hazards. The
Department's inspection form also references the "Colorado Solid Waste Disposal
Sites and Facilities Law" Minimum Standards, CRS 30-20-110. The Division has
requested that the Archuleta County Commissioners inform them of the plans to
bring the site into compliance or close it.
The purpose of this part of the report is to evaluate the Pagosa Springs
disposal site and to investigate the feasibility of upgrading the site to comply
with RCRA regulations. The scope of work is to: (1) identify the deficiencies
of the current operation of the disposal site with respect to the State and
Federal regulations; (2) develop an overall upgrading strategy (including
upgrading costs); (3) develop an operational plan (defining staffing needs,
17
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equipment needs, etc.); (4) develop an implementation strategy for the proposed
plan; and (5) review and comment on the user charge system for the disposal
site.
B. Identification of Deficiencies
Cover. The major deficiency of the Pagosa Springs landfill site is its lack
of suitable cover material. Suitable soil for covering the refuse each day is
of utmost importance for the safe and sanitary operation of a landfill. Cover
material is needed to prevent rodents from burrowing into the fill, keep flies
from emerging, minimize the entrance of moisture in the fill, provide a pleasing
appearance, control blowing litter, and control erosion. Figure 4 depicts in
general terms the suitability of various soil types for cover material.
Table 5 shows the soil survey interpretation by the U.S. Department of
Agriculture, Soil Conservation Service, for the predominant soil type located at
the Pagosa Springs landfill area, namely the Ml-CE soil. The table shows that
the topsoil at the site is unsuitable for cover material. It is shallow soil to
bedrock (approximately 12 inches) and consists of a predominantly stony sandy
loam which has a high permeability, 2.0-6.0 inches/hour.
Also shown in Table 5 are the estimated physical and chemical properties
affecting the soil as a cover material, and the degree of limitation and major
soil features affecting selected use.
In the past, both Pagosa Springs and Archuleta County have hauled fill
material to the site from road construction and excavations activities. This
material, however, was dumped at the site and used to provide a working surface
for vehicles dumping at the site. For proper operation of a landfill at the
Pagosa Springs site additional fill will have to be hauled to the site. This
will result in additional cost to the Town for operating the landfill. Poten-
tial sources of cover material are identified in Section C and the costs of
procuring and hauling the cover material are presented in Section E of this
Chapter.
A less permeable soil will have to be located and utilized to prevent
leachate production and ensure the safe and efficient operation of the landfill.
18
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FIGURE 4
SUITABILITY OF SOILS FOR LANDFILL OPERATION
100
Acceptable soils
•• /3^1^K%jj^^^ *
A A<£A^S£>?3^>c<^^^
Percent Sand
Suitability of General Soil Types as Cover Material.3
Function
Clean Clayey-silty Clean dayey-silty
gravel gravel sand sand Silt Gay
Prevent rodents from burrowing or tunneling
Keep flies from emerging
Minimize moisture entering fill
Minimize landfill gas venting through cover
Provide pleasing appearance and control
blowing paper
Crow vegetation
Be permeable for venting decomposition gas
G
P
P
P
E
P
E
F-G
F
F-G
F-O
E
G
P
G
P
P
P
E
P-F
G
P
G
G-E
G-E
E
E •
P
P
G
G-E
G-E
E
G-E
P
P
Eb
Eb
Eb
E
F-G
P
aE-excellent; G-good; F-fair, P-poor.
Except when cracks extend through the entire cover.
cOnly if well drained. i
Source: Reference 2.
19
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Surface and Ground Water Pollution. Leachate production in a landfill might
result in the pollution of surface water bodies and ground water. As mentioned
in the previous section, the topsoil in the area is very shallow (approximately
12 inches) and, therefore, provides very little cover material for the site. It
is also quite permeable. The bedrock at the landfill is the Dakota Sandstone.
If fractures are present in this rock unit, and if leachate is generated,
percolation could take place down to the ground water without benefit of much
filtration by the soil or bedrock, thus contaminating the ground water. Frac-
tures can be observed at points where the bedrock outcrops or soil can be
stripped from the surface to expose the bedrock. Pagosa Springs can coordinate
the bedrock fracture analysis with the State Health Department if the necessity
of a groundwater monitoring program is in question.
•
To investigate the potential for leachate production, a watei* balance
analysis is presented in Table 6. This water balance analysis is based on the
generally accepted methodology outlined in EPA Report SW-1686. As pointed out
by the EPA, the water balance method will serve as a useful engineering tool in
conducting environmental assessments of proposed or existing landfill sites.
However, it should be remembered that the method is intended only as a basic
tool for the engineer, and certain site specific assumptions will be necessary
to tailor the method for a particular location.
The clay loam C2-CD is used as the expected cover material for analysis.
This soil has an available water holding capacity of as much as 0.2 inch per
inch of cover or 4.8 inches for 24 inches of cover (2 foot final cover).
Monthly precipitation and evapotranspiration are as stated in the introduction
sections of this report. A relatively high runoff coefficient of 0.35 is
assumed. This means that 35 .percent of the precipitation will be runoff and 65
percent will infiltrate the ground surface. EPA Report SW-168 estimates that
grass covered heavy soil on*a 7 percent slope will have a coefficient between
0.25 and 0.35 while the Pagosa Springs landfill has a 10 percent slope and
intermittent shrub growth. The conclusion of this analysis, as presented in
6 Source: Reference 6.
20
-------
7A13LE 6. MONTHLY WA'[£3 BALANCE ANALYSIS
IN MILLIMETERS FO* PA30SA SPJINGS, C
Parameter'
Average Precipitation
(P) -
ftutt&ff
ODD
0 0 D
Apr
S4
.12 •
22
71
-49
-343
- 8
-4
26
G
— ,
25
9
1?
95
-32
-426
4
-4
21
a
"Dun
2-i
9
16
119
-103
-526
2
-2
16
D
3ul
40
14
26
l»
-S4
-623
1
-1
27
0
Aix, bap
59 45
a is
33 25
104 82
-co -S3
-6S9 -742
1 1
C 0
33 29
•3 0
-------
Table 6, is that no percolation will occur which could contribute to leachate
production at the landfill.
It should be pointed out that only the 24 inches of final cover material was
used to calculate leachate percolation. Like its cover material, the underlying
solid waste cells (including the relatively thin layers of daily cover material)
will exhibit a certain capacity to hold water. The field capacity of solid
waste has been determined by many investigators to vary from 20 percent to as
high as 35 percent by volume?. The ability of waste to hold water, a factor not
included in the water balance analysis, will further retard leachate generation
and movement.
The aquifer underlying the landfill site is the Dakota Sandstone which is
used in some areas of the County as a domestic water suppl»y. The direction of
ground water flow is predominantly to the east towards its discharge point at
the San Juan River. A potentiometric surface map for the Dakota Sandstone pre-
pared by GallowayS indicates that, at the Pagosa Springs landfill, depth to
ground water may be well over 100 feet below the ground surface (see Figure 5).
According to the map, the elevation of ground water in this aquifer varies
between 7,150 and 7,200 feet at the site while the elevation of the landfill
land surface varies between 7,270 and 7,330 feet (it averages 7,300 feet). Two
domestic water wells exist in the vicinity of and upgradient from the landfill,
wells 23 DO and 26 BD, presented in Table 7. The depth to water in these wells
is somewhat shallow at 5 feet in 23 DO and 39 feet in 26 BD. The shallow water
depth at these two well sites, however, cannot be extrapolated to represent
conditions at the landfill site. This is because the land surface elevation of
these wells is lower than the elevation at the landfill site. The land surface
elevation at the two well locations is therefore closer to the ground water
level.
7 Source: Reference 2.
8 Source: Reference 7.
22
-------
, Well
/ '33tO
water level
I measured
1 '
s2£ A , &
leveL,,O LANDFILL
Road to Trujillo
1 Ground surface'elevation of the landfill
\ varies from 7270 to 7330 feet.
FIGURE 5.
ELEVATION OF THE POTENTIOMETRIC SURFACE, DAKOTA SANDSTONE
23
-------
TABLE 7.
WELL INVENTORY. PAGOSA SPRINGS AREA. COLORADO
WF.lt
LOCATION
02WI5DAA
02UI500
02WISCB2
02UISACI
02UISACA2
02WISCA
02UISAC1
02WI5CC
02UI50A
02WI5BD2
02WI6BAAA
02UI6AOC
02UI6DAI
02WI6DA2
02W200BI
02U20082
02U200B1
02U200B4
02U200C
02U200BA
02U200BB
02W20CO
02U1200BS
02U2008S
02U200BI
02W20BO
02W20AB
02U2IBCD
02U2IBOB
02U2IAB
02U2IBB
02W22CC
02U21AD
02W23A02
02U23AC
02W23ABI
02U230D *
02W23DA
02W230B
02W21AB2
02W240B
02W24BC *
02W26BO
"OZU260C
02U27AOA
02W29CB
fLCVATION
(ft above
HSL)
1580
1480
1602
1620
1620
IS80
' 1600
7510
ISOO
1600
1560
1610
7595
IS9S
1540
7540
IS40
1540
7540
IS29
1524
ISIS
1540
IS40
IS40
IS20
I49S
7517
ISOO
1160 •
1140
1140
1260
1260
1200
1180
1210
1260
7100
1200
7085
1160
M3S
UAIfft LfVEL
UCLl CASINO DEPTH DAII
DEPTH OIA. (ft) HEAS.
(ft) (In)
68 SB
67
107
81
110
70
IS
94
80
90
70
100
120
104
200
110
IB
12
91
10 1
too
82
66
10 1
US
IJ
IIS
IS
IS
200 '
42
4*
110
SO
52
2$
SI
21
10
100
20
SO
4$
140
56
54
40
90
48
20
40
1/2 10
20
22
S/B 210
2SO
IS
S/B 12
S/B 10
S/B 10
26
I/B 60
••
12
10
U
16
60
!)
0
S
B
IIS
20
Flowing
SO
21
12
S/B 10
S/B S
Iff
6
41
12
22
19
BS
110 < 1/4 20
65 C 45
t/l/66
2/12/66
1/1/66
7/31/66
9/28/66
10/24/66
10/10/61
11/12/10
11/6/72
9/20/IS
4/14/72
6/19/71
9/2B/6S
9/9/71
1/28/66
1/25/66
1/25/66
4/19/66
1/16/61
1914
S/ll/SI
8/15/67
11/27/61
11/15/69
10/2/69
9/21/72
5/23/62
5/13/42
IO/I2/6S
(/IS/10
9/25/71
6/8/58
11/3/68
II/I6/7B
1/5/70
5/11/70
8/17/71
6/29/74
9/6/11
S/l 1/66
5/1/70
4/26/66
t/tt
7/21/74
8/30/71
fLCVATION
(ft above
IISL)
ISZt
1424
IS4B
7510
7532
ISBO
7470
1490
7510
IS3B
1140
IMS
ISBO
ISOB
7510 .
7510
ISM
1447
I4S2
MBS
IS24
7506
MBO
7507
7435
1142
MBO
' 1160 »
1090
III!
I22B
I2SO
719$
7170
1204
1211
7078
7161
1000
1140
1190
USE
0
D
D
D
D
0
0
0
D
0
0
C
1
0
C
0
0
0
0
C
0
0
0
0
D
0
D
0
D
0
0
0
0
D
D
0
0
D
D
D
0
0
D
0
0-
PlIWltM
Yield Drawdown
(GfH) (ft)
i SB-
lp 101
i
i
i
i
i
l
i
i
100
16
160
IS
65
80
11
10
0
120
90
ISO
60
16
SO
to
10
ss
64
IS
(S
BS
190
10
IS
10
41
45
16
24
(S
12
40
10 15
4 91
10 60
1 Date
• Capacity
(gp-m)
.OS
.1
1.01
.OS
.01
.0$
.08
.01
1.16
.01
10
.14
.01
.01
.07
.11
.1
.1
.01
.11
.09
.11
.01
.14
.01
.11
1.0
.14
.14
• .11
.18
.25
.12
.42
.11
.29
.04
.17
Aquifer
D
0
D
H-
D .
D
H
0
D
D
D
0
0
D
0
0
D
0
D
D
D
0
0
D
0
0
At
A
H
H
0
0
0
0
0
D
0
D
0
A
H •
D
HT
H
D
Owner
Robert Snow
Hilton 0. Reney
Gerard Crlpe
Henry Irujllle
Santana Lujon
Forreit (. Boianl
C. E. Gay
Fred Harnon
Robert Snow
Itt Aisenbly of God CM.
Stanley Belaear
Over Niter Inc.
R. J. Sullivan
Fred Ebellng
NavaJo frail lruct-0-lal
Jin Garven
Bernle Harrll
H»«-ol Ilirrli
H. U. Hendal
Ut. William
Eaton Ihduitrlet
F. A. IhOMpson
Hllo Sulth
H. I. William
H. T. William
Vern I. Sulth
H. W. Hendell
J. F. Whltefleld
J. F. Uhltefleld
Herbert II inner
NavaJo Trail Corp.
U. W. Scogglnt
W. F. Wall
Donald Hartlnei
Roger Sanchef
Reymndo Kiel .
David Haez
Reynundo Haei
Felipe Haei
Reyaundo Haei
A. H. Co»ei
llarland Pierce
John Snow
Jeanette S«llh
UK. V. Flowert
llarley Herrlck
Wells upgradlent of landfill.
a
Source: Reference 7.
-------
Although some potential for ground water contamination exists by virtue of
the soil and hydrogeological conditions, it can be concluded that leachate
production should be virtually nonexistent at the site because of the low level
of precipitation and high degree of vegetation in the region. Field inspection
of the site confirmed that steady leachate seepage from the fill toe could not
be observed.
The steepness of the slope, estimated at approximately 10 percent, and the
low-permeability clay loam soil will also contribute to runoff and will increase
the speed of the runoff. Surface runoff from the site is not expected to affect
surface water quality. It may, however, affect erosion. Surface water diver-
sion structures must therefore be considered to mitigate this problem.
Burning. Open burning commonly occurs at the site. Frequent, if not daily
outbreaks of smoke and flame occur. Town officials indicated that attempts to
put out the fires have never been successful. Open burning is not consistent
with the safe operation of a landfill. In addition to creating a safety hazard,
open burning will result in air pollution and aesthetic problems in the area.
The Colorado Solid Waste Disposal Sites and Facilities Law - Minimum Standards
prohibits the open burning of solid waste deposited at any site and facility
except by incineration or in extreme emergencies under controlled conditions and
as authorized by the Department of Health.
Fencing/Access. The area is enclosed by a barbed wire fence that prohibits
the entry of cattle and other large animals. Smaller animals, however, can gain
entry to the site. The fence will not prevent blowing debris from being scat-
tered outside the site area. Currently there is no barrier prohibiting un-
authorized access to the site. Access to the site is through a steep paved
all-weather road off Route 145. The on-site access is a dirt road leading down
into previously filled areas.
Blowing Litter and Dust. At the time of the site inspection the soil was
moist and there was little problem with blowing litter or dust. However, wastes
are tossed from the top of the dump down onto the steeply sloping open face
(east face). There is no evidence of soil covering the exposed face of the
refuse pile which is approximately 20-feet high. Therefore, there is no control
being exercised to prevent blowing litter.
25
-------
Waste Types Accepted. Currently, the operation consists of a dumping area
where wastes are deposited on the edge of a steep embankment built up by pre-
viously deposited waste. There are no controls over the kinds of wastes
accepted at the site. About 20-25 abandoned car bodies are located in one area
of the site, and the drum of a truck-mounted rotary concrete mixer is also on
the site.
C. Upgrading Strategy
Sources of Cover Material. As mentioned in Section B of this chapter, the
topography and geology of this area are such that there is very little topsoil
available for use as cover material.Therefore, suitable soil, which is vital to
the sanitary operation of the landfill, will have to be hauled to the site. The
costs involved with providing proper cover material will be presented in the
upgrading costs section of this chapter.
To locate suitable sites for obtaining cover material, the areas containing
Mancos Shale were investigated. Mancos Shale locations were chosen as potential
borrow areas for cover material due to the soils associated with the Mancos.
Soils on the Mancos include the previously discussed Yawdim clay loam (SCS
symbol CO-CE) and the Work loam (SCS symbol C2-CD). The Yawdim clay loam is not
the ideal final cover material because of the high percentage of ground-up shale
and sandstone it will contain as a result of the excavation operation. The
ground-up shale is very inert and it would be difficult to establish plant
cover on this material. It is, however, quite suitable for daily cover
material. The Work loam (SCS symbol C2-CD) is rated quite good for daily and
final cover material. Soil from the top three feet is the best soil for plant
growth.
The locations of the potential borrow sites were determined from a geolo-
gical map of the Pagosa Springs area9. Areas consisting of Mancos Shale (a
clay-like material) within a 3 to 4 mile road distance from the landfill and
9 Source: Reference 12.
26
-------
haul distance, and hence the cost of the cover material. Figure 6 is a portion
of the geological map of the Pagosa Springs area. Highlighted are areas
designated "Km" (Mancos Shale) and described as C2-CD and CO-CE soils. These
are possible sites where cover material may be obtained. (Note: the numbers in
Figure 6 depicting the potential borrow locations are quarter-quarter section
numbers of Standard Township Range 2 West, Township 34 North (23 NWNW refers to
the NW quarter of the NW quarter of Section 23 of Township R2WJ34N.
Ground Water Monitoring. Within a 1/2 mile of the landfill, there are
two private wells tapping the aquifer in the Dakota Sandstone formation on which
the landfill is sited (see Figure 5). The wells, identified as 23 DO and 26 BD
in Figure 5 are, however, upgradient from the site. By interpolation, lines of
equal elevation of the potentiometric surface show the ground water level in the
vicinity of the landfill at 7,175 feet compared to 7,180 feet for well 23 DO and
7,190 feet for well 26 BD. (These same wells are listed in Table 7 with the
identifying prefix 02 W). As mentioned previously, these two wells are used for
domestic water supply and yield relatively small amounts of water. The pumping
rates and the resulting cones of depression for the wells are of such magnitude
that it is unlikely that ground water would flow towards the wells from the
landfill. Because of the location of these two wells, they cannot be used to
detect ground water contamination down-gradient from the landfill; they can,
however, be used to obtain background water quality data and to measure ground
water elevations. There are no wells in the Dakota Sandstone aquifer down-
gradient and in the vicinity of the landfill site.
There are two alternatives for monitoring the ground water quality in the
area: 1) either well 23 DD or 26 BD can be utilized as an up-gradient well and
one to three wells can be drilled down-gradient in the aquifer and the water
tested for possible pollution from leachate production; or 2) no action, or in
other words, no attempt at monitoring will be made. This report recommends that
no monitoring wells need be drilled because initial calculations indicate essen-
tially that no leachate generation will occur in this arid region. The added
expense of establishing an independent new ground water monitoring system
appears unnecessary for this site. However, the Colorado Department of Health
has the final authority to determine the need for ground water monitoring.
27
-------
9 POTENTIAL
"ORROW SITE
R 2 W T a* N
' 1 4 N W 3 W\
FIGURE 6. POTENTIAL BORROW SITE LOCATIONS
28
-------
If nearby landowners seek reassurance that the ground water is indeed not
being polluted, the monitoring program in alternative 1 could be used. Instead
of drilling a well upgradient from the site, the two existing wells upgradient
from the landfill could be sampled periodically (two to three times a year) and
their water analyzed for leachate contamination. The Environmental Protection
Agency (Fenn, D. G. et al., Procedures Manual for Ground Water Monitoring at
Solid Waste Disposal Facilities, U.S. Environmental Protection Agency, Report
SW-611, Washington, D.C., 1980.) recommends using the following key indicators
for determing potential solid waste landfill contamination: specific con-
ductance, pH, chloride, iron, color, turbidity, and COD.
Surface Drainage Improvement. Since rainfall will most likely result in
rapid runoff because of steep slopes and shallow depth to bedrock, diversion
ditches should be provided around the top slope between the road and the land-
fill to divert water from adjacent areas from flowing onto the landfill. This
will direct the run-on around the site and futher prevent potential contaminated
run-off and percolation of the water through the fill, and minimize erosion as
well. Although leachate production does not seem likely, such preventive
measures minimize any risk or potential impacts.
Site Cleaning and Preparation. The first step in cleaning the site is to
properly dispose of the junked automobiles and the concrete mixer drum. A U.S.
EPA studylO has shown that small communities can successfully handle their
junked automobile problems. One of the important requirements is that the
community should have access to a vehicle processor or dismantler who can
recycle the junked automobiles. San Juan Resource Recovery in Durango has
hauled junked cars from the Southern Ute Indian Reservation. This company
should be contacted to determine if it is interested in taking the junked
automobiles from the Pagosa Springs Landfill.
Source: Reference 4.
29
-------
If recycling is uneconomical, the junked automobiles should be flattened
and buried on site and the mixer drum should be cut in several pieces using a
welding torch and similarly buried. The junked automobiles, once flattened, can
be laid side by side along the active face of the dump and covered along with
the waste; placing the flattened automobiles in a methodical fashion along the
toe of the active face would assist in providing a degree of slope stability.
The inactive portion of the site should be covered with two feet of
compacted low permeability soil as a final cover. The active portion is on a
face that may be too steep to permit efficient operation of a bulldozer. Enough
cover will have to be hauled to the site to cover the exposed refuse with a
6-in. cover at the end of each day and to reduce the slope of the active face to
provide a better working surface for the bulldozer. Cost figures are presented
in the upgrading costs section of this chapter.
Subsidence and Slope Stability. Two potential operational hazards, which
were not in evidence during the field investigation, were postulated by the
Colorado Department of Health—subsidence and slope instability. These two
q£-
interrelated problems might occur as a consequence of open burning at the land-
fill and as a result of an active fill which is steeply sloping, particularly at
the working face. Although a rigorous analysis consisting of the collection and
interpretation of laboratory and field data is beyond the scope of this study,
the initial conclusion, based on historical record and the proposed strategy for
closing the inactive portion and for future landfill operations at the site, is
that neither subsidence or slope stability will present significant problems.
At the Pagosa Springs landfill, subsidence might result from biological
decomposition and/or past burning practices. Biological decomposition of
organic matter in the solid waste occurs gradually over a number of years. The
amount of organic matter in the existing fill has been reduced substantially due
to the past practice of burning nearly all combustible materials. This practice
reduces the potential for subsidence resulting from biological decomposition but
increases the potential for the creation of voids due to pockets of smoldering
refuse. However, the relatively shallow depth of the landfill (approximately 20
feet or less), the cover material which has been placed over most of the in-
active fill (albeit intermittently), the inactive fill's ability to support
30
-------
vehicular traffic, and the lack of subsidence to date point to the relatively
low possibility of significant subsidence occuring in the future, especially if
the inactive fill is closed and future operations are implemented as proposed in
this report. Vehicular traffic should not be allowed on the inactive site to
further reduce the possibility of subsidence.
Related stability problems could potentially occur in two ways. The
working face, which is currently very steep, could slump or, additionally, all
or a portion of a cell could slide along the underlying sandstone bedrock.
Also, it is conceivable that the two potential stability problems could act in
tandem. A slumping failure in the inactive fill would initially be retarded by
the proposed new cell construction (new cell construction is described in the
next section). However, the additional pressure created by such a potential
failure might contribute to sliding failure in the new cell configuration.
Preliminary stability calculations based on conservative assumptions re-
garding the refuse and the underlying sandstone indicate a static safety factor
ranging between 1.4 and 2.0. This safety factor range and the lack of evidence
of past slumping or sliding support the premise that slope stability will not
represent a significant problem at the Pagosa Springs Landfill.
If signs of subsidence or slope instability become evident, Pagosa Springs
should engage a local engineering firm to conduct a rigorous analysis based on
comprehensive laboratory and field data.
Preliminary Landfill Operation and Site Layout. If the site is to continue
operation while the upgrading strategy is being carried out, the following steps
should be followed:
(1) direct landfill users to the active portion of the fill by providing
a well defined access road. Identify the dumping area with a sign;
(2) begin covering operation by spreading final cover from the top
portion of the used fill toward the active portion;
(3) construct a diversion ditch along the top slope of the finished and
covered landfill site;
(4) construct a diversion ditch culvert under the access roadway where it
intersects the ditch;
31
-------
(5) plant vegetation as soon as possible after the cover is completed.
Upgrading Costs. The major cost involved in upgrading the disposal site is
the purchase and transport of soil to be used as cover. In addition, a
diversion ditch should be provided for redirecting surface drainage.
Revegetation of the closed and covered portion of the site should also be
accomplished to prevent erosion. Final grading of the closed landfill to a
gradual slope will minimize erosion. Table 8 is an itemized listing of the
capital costs for upgrading the disposal site. The table lists the items
necessary for bringing the landfill into compliance with State law. (The table
does not indicate the items or cost necessary for continued operation of the
fill. Such data are presented in Table 11, Pagosa Springs Annual Landfill
Operations Cost).
The quantity of fencing is based on enclosing the entire perimeter of the
site. The dimensions of the site are rough estimates. Ditching is for diver-
sion of surface run-on. It is estimated that ditching will only be required for
the west side of the fill adjacent to Trujillo Road. The length of the ditch is
approximately 600 feet. Based on the tocal climate and geology the final cover
selected need not be completely impermeable, as such material is costly and
difficult to obtain. There are possible sources for obtaining cover materials
within a three and one half mile radius of the landfill as shown in Figure 7.
The unit cost for the cover material is based on availability of cover material
within three and one half miles of the landfill. In Table 8, the calculation
for final cover assumes a three acre landfill area covered to a depth of two
feet.
To ensure that the final cover placed over closed portions of the landfill
is protected from erosion and kept intact, the revegetation of the final cover
must be performed in a careful and methodical manner. Revegetation with seeds
and plants which will grow well in the relatively dry Pagosa Springs climate and
resist erosion is best for the landfill. Western Wheat and Crested Wheat grass
would be good choices for seeding; examples of woody shrubs which are climatic-
ally suitable and would have adequate space for their root zones in the two feet
of final cover are Sumac, Hansen Rose, and Nanking Cherry.
32
-------
TABLE 8
PAGOSA SPRINGS LANDFILL UPGRADING COSTS3
Item
Fencing (stock, 4' high)
Diversion Ditching
Final Cover (permeable,
off-site source
transport @ $ .84/
yd.3, material @
$ .30/yd.3, placement
@ $ ,56/yd.3, 3 mile
average transport
distance)
Cover for Working Face
(same assumptions as
final cover)
Revegetationc
Dismantle Concrete Mixer
(skilled welder)
Flattening and Burial of
cars (labor only)
Dozer Rental (270 HP)
OPTION:
Ground Water Monitoring
Well (does not include
sampling)
Unit Cost
$3.30/1inear
ft.
$2.70/1inear
ft.
$1.70./yd.
$1.70/yd.3
$l,170/acre
$14.9tF/hour
$12.60/hr.
Quantity
2,200
ft.
600 ft.
16 hr.
$2,457/week 4 weeks
TOTAL
$l,170/well 2
TOTAL
Total
$7,300
1,600
10,000b yd.3 17,000
1,000 yd.3 1,700
3 acres 3,500
16 hr. 240
200
$2,300
$43,600
a Source: Unit costs were derived from the 1979 Dodge Guide
(Reference 5) and the 1976 Building Construction Cost Data
Handbook (Reference 3). These figures were converted to 1980
dollars by using the 1980 Product Price Index (Reference 9).
b 3 acres x 43,560 ft.2/acre x 2 ft.
27 ft.3/yd.J
c Cos
t for revegetation developed by Fred C. Hart Associates,
33
-------
The Work Loam soil recommended as the soil to be used for final cover is
sufficient if the following revegetation program is executed: the revegetated
area must be properly prepared (discing, harrowing, etc.). fertilized, seeded,
woody shrubs transplanted, and mulched. Simple seed broadcasting over the area
to be revegetated will not be sufficient.
The revegetation cost of $1,170 per acre in Table 8 includes seed bed
preparation, fertilizing, seeding, transplanting, and mulching. Following
revegetation and closure of the landfill, periodic visual inspection of the site
(on the order of 2 to 3 times per year) should be performed to ensure that
erosion is under control and that the final cover is intact.
A rented Caterpillar Model 08 bulldozer and a dozer operator will be needed
to flatten the cars and cover them at the working face. If operation of the
site is to be discontinued, it will be necessary to use a dozer to grade the
site and apply the final cover. Although a machine with the horsepower output
of a D8 dozer will be needed to flatten the junked automobiles, such a large
machine would not be required to close out the site nor for daily landfill
operations—a Caterpillar Model D6 crawler dozer is a more properly sized piece
of equipment for the Pagosa Springs landfill. The County, therefore, could
reduce the overall rental cost significantly through the expeditious purchase of
the D6 crawler dozer (see Section E of this chapter). The abandoned concrete
mixer drum cannot, however, be flattened by a bulldozer and a skilled welder
will therefore be needed to dismantle it.
The ground water well drilling costs are shown in the event that the Town
decides to monitor water quality in the Dakota aquifer down-gradient from the
landfill. Well sampling costs are recurring costs and are not included in the
analysis.
0. Estimated Life Of Landfill
In order to estimate how many more years the Pagosa Springs Landfill can be
used, it is necessary to calculate the total capacity of waste the remaining
landfill area will hold and compare this to the amount of waste that is being
generated now and will be generated in the future. The available landfill
34
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capacity refers to the volume of waste that can be contained and not to the
additional volume necessary for the cover material. The area of the disposal
site available for use is a keystone shaped area beginning at the access cut to
the fence line at the bottom of the slope. The site is 500 feet across at the
top near the existing fill, 300 feet along the sides, and 400 feet across at the
toe of the site. On the unused portion of the landfill the slope is
approximately 10 percent. To estimate the life of the landfill, it will be
assumed that the slope will be kept at 10 percent. There is a 20-foot drop at
the working face of the fill, and it will be assumed that the landfill cells
will be stacked in such a fashion as to achieve a 20-foot height for the first
stack of cells. Each successive stack of cells will be lowered 8 feet for each
50-foot length to achieve the assumed 10 percent slope. Figure 7 shows a
schematic of how the cells will be stacked and the approximate dimensions of
each stack. With this configuration, it is estimated that approximately 51,600
cubic yards of refuse can be contained in the unused portion of the Pagosa
Springs Landfill. The calculation of this figure is presented in Table 9. The
volume of cover material necessary with this layout is computed in Table 10.
Approximatley 14,000 cubic yards of cover will be needed during the remaining
life of the landfill. r
To arrive at the estimated life of the landfill, the number of cubic yards
of solid waste that can be contained in the unused portion of the landfill was
divided by the number of cubic yards of waste generated per year. It is assumed
that in the study area approximately 4.0 pounds of waste are generated per
person per day.12 in the landfill, waste will compact to a standard compaction
ratio of 800 pounds per cubic yard.13
Using the projected 1985 Pagosa Springs population figure of 5,618, approxi-
mately 10,250 cubic yards of. refuse will be generated each year for the next
five years. The calculation follows:
12 Source: Reference 11.
13 Source: Reference 2.
35
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CELL STACKS
DAKOTA SANDSTONE
BASE
Final Cover
Daily Cover
FIGURE 7. SCHEMATIC OF LANDFILL CELLS
36
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TABLE 9
ESTIMATED AVAILABLE LANDFILL CAPACITY (REFUSE)
Number
Cell Of Cells and
Stack No. Heights (ft.)
Number Of Number Of
Cell Dimensions (ft.) Cubic Ft. Cubic Yd.
Height Length Width
1 3 9 5.5 each
2 3 @ 4.5 each
3 3 @ 3.5 each
4 2 @ 4.0 each
5 1 § 5.5 each
6 1 (3 2.5 each
16.5 x 50 x 500
13.5 x 50 x 500
10.5 x 5Qr x 500
8 x 50 x 475
5.5 x 50 x 450
2.5 x 50 x 425
412,500
337,500
262,500
190,000
124,000
53,000
15,500
12,500
10,000
7,000
4,600
2,000
TOTALS
1,380,000
51,600
37
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TABLE 10
ESTIMATED VOLUME OF COVER MATERIAL
Cell Stack No. Dimensions (ft.)a
Cubic Ft.
Cubic Yd.
1
2
3
4
5
6
TOTALS
3.0 x 50 x 500
3.0 x 50 x 500
3.0 x 50 x 500
2.5 x 50 x 475
2.0 x 50 x 450
2.0 x 50 x 425
75,000
75,000
75,000
59,400
45,000
42,500
372,000
2,800
2,800
2,800
2,200
1,700
1,600
14,000b
a This dimension includes all daily and final cover requirements in the
cell stack.
b Approximately 70 percent, or 9,800 yd.3, will be used for final cover,
38
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5,618 persons x 4 Ibs/person/day x 365 days/year
800 lbs./yd.3
= 10,250 yd.3/year
This figure computes to a generation rate of roughly 11 tons per day in the
study area. If the total refuse capacity of the landfill (51,600 yd.3) is
divided by the amount of waste generated each year (10,250 yd.3), the life of
the site will be five years:
51.600 yd.3
10,250 yd.3/year
= 5 years
E. Landfill Operational Plan
Staffing Needs. The landfill will handle an estimated 11 tons per day
between 1981 and 1985 (population 5618^x 4 Ibs per day per person). For this
size landfill only one operator will be necessary. This operator should be
employed on a full-time basis.
Equipment Needs. A crawler dozer will be needed for spreading the waste
and grading the site. The dozer should be equipped with a U-shaped blade that
has been fitted with a top extension to increase its pushing area. A dozer of
this type can perform multiple functions such as compacting, moving heavy
materials, and covering and grading the fill. A small gatehouse will be needed
to provide a shelter for the landfill operator during inclement weather and to
provide a place to store the landfill records and tools. A portable toilet for
the sanitary convenience of the operator should also be provided. The toilet
could be acquired on a rental or lease agreement. A fire extinguisher,
first-aid kit, and hand tools should be kept on site. Additionally,
professional engineering services should be procured to assist the town in
implementing the continued operation of the landfill. Other equipment needs
such as commodities (office supplies, fuel oil, etc.), contractual services
(printing, telephone, utilities, etc.) will be itemized in the next section on
operating costs.
39
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The Town purchased a used crawler tractor for $13,500 in January 1981 to
upgrade the landfill operation. The tractor is a 1974 John Deere Model 450B
which has a 65 horsepower engine. The tractor is used exclusively for landfill
operation and is kept at the site. It is equipped with a bulldozer pusher
blade. This piece of equipment is too old and small for the landfill operation
and the County will, therefore, need to purchase at an estimated cost of $32,000
a Caterpillar Model D6 crawler dozer.
The County has supported the Town by loaning a crawler Caterpillar Model D6
and operator on special occasions. (The County dozer is also equipped with a
ripper as well as a bulldozer blade). This equipment could still be used as
backup if the Town's Model D6 crawler dozer (yet to be purchased) should become-
inoperative. Other County equipment has been used to haul fill material to the
landfill. This equipment includes five dump trucks and a 1 1/2 cubic yard
front-end loader.
All of the above items are capital costs; the cost of each item is pre-
sented in Table 11. Assuming that the town would secure a loan to pay for the
capital costs, and retire the debt ove£. the remaining life of the landfill, the
total capital cost is amortized over 5 years using the capital recovery factor
(CRF) for a uniform series for 5 years at 12 percent interest (0.277).
Annual Operating Costs. Table 11 also itemizes the costs which will be
incurred each year. The hourly wage including fringe benefits for the equipment
operator was taken from the Dodge Guide to Public Works and Heavy Construction
Cost for 1979. The rate is based on that for the City of Denver, less twenty-
five percent to reflect reduced rural wage rates. Costs for commodities and
contractual services were taken from one of the Pagosa Springs expenditures
budget dated September, 1980. Office Supplies, fuel oil and gravel are all
annual costs.
For the daily and final cover, it is assumed that a fifth of the landfill
cover will be needed each year to operate the landfill. Therefore a fifth of
the total cost for cover material was attributed to the yearly cost.
40
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TABLE 11
PAGOSA SPRINGS ANNUAL LANDFILL OPERATIONS COST3
Item
CAPITAL COSTS
Hand tools
Signs and posts
Fire extinguisher
Operator building
Portable sanitation
Crawler dozer
Office equipment
Engineering fee
Unit Cost ($)
200
100
50
5,000
500
32,000
500
3,800
Quantity
1
1
1
1
1
1
1
1
Amortized capital cost
Total Capital Cost
(5 years, 12% interest)
ANNUAL OPERATING COSTS
Equipment operator
(including fee
collection 8.48/hr.
Office supplies 300
Fuel oil 1,560
Gravel 500
Printing 200
Telephone 150
Utilities 750
Cover material
Final cover 1.70/yd.3
Daily cover 1.70/yd.3
Terrace Erosion Protec. 6/linear ft.
Revegetation 1,170/acre
2,080 hr.
9,800 yd.3/5 years
4,200 yd.3/5 years
2,850 ft. /5 years
4 acres/5 years
TOTAL
Plus Amortized Capital Cost
TOTAL
Add for groundwater monitoring
if required: 2 wells @ $500 per
well (includes 2 samples and
analyses per year).
1,000
Total
Cost ($)
$200
100
50
5,000
500
32,000
500
3.800
42,200
11,700
TOTAL
17,640
300
1,560
500
200
150
750
3,300
1,430
3,420
940
30,200
11.700
41,900
1,000
42,900
a Unit costs were derived from the 1979 Dodge Guide
ing Construction Cost Data Handbook (Ref. 3). All
dollars using the 1980 Product Price Index
developed by Fred C. Hart Associates, Inc.
(Ref. 5) and the 1976 Build-
costs were converted to 1980
(Ref. 9). Revegetation cost
41
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The transport of cover material is a task that will need to be privately
contracted or done using County or Town equipment and personnel other than the
landfill operator and the equipment provided at the landfill. Cover would be
trucked to the site at a rate which takes into account available storage area on
site, cover consumption rate on site, weather, and the hauler's excavation and
hauling capability. The cost of delivery is included in the estimated unit cost
of cover material, Table 11. The estimated annual rate of delivery of cover
material would be on the order of 2,800 cubic yards.
Similarly, revegetation was assumed to occur over a 5-year period; there-
fore, the annual cost of revegetation was calculated by dividing the total cost
by 5 years. Annual costs for ground water sampling and analysis are included if
the Town chooses to institute a ground water monitoring program.
Operational Plans. The hours of operation of the landfill should be set at
a convenient time for the users taking into consideration that the operator
should work a 40 hour-week five days per week with one of these days on the
weekend to accomodate persons who are able to haul to the landfill only on their
<£-
day off. The landfill could then be closed on one week day. One possible work
schedule could be at 8:00 a.m. to 12:00 noon and 12:30 p.m. to 3:00 p.m. The
operator's hours could be from 8:00 a.m. to 4:00 p.m. with an half hour for
lunch at noon when the landfill will be closed. During the time when vehicles
are not entering the landfill, the operator should be operating the dozer to
spread the waste. At 3:00 when the landfill is closed the operator should apply
the daily 6" cover. During the hours the landfill is open to the public, the
operator should collect the disposal fees.
F. Methodology For Implementing Proposed Plan
When the decision is made to implement the plan, a logical procedure for its
smooth development should be followed. The following is a step by step listing
of the surveying, engineering and construction, and ground work which must be
done to implement the plan:
Surveying. An engineering survey of the area should be made to establish
the exact dimensions of the entire disposal area, and also the dimensions of the
42
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unused portion of the landfill. If surveying records exist, they should be
utilized. The survey report is the first step toward implementing the plan.
Accurate measurements must be made because all subsequent design criteria are
based on such data.
Engineering and Construction. The first step toward the engineering
implementation of the proposed landfill upgrading must be to obtain suitable
daily and final cover material. The success of the operation will hinge on the
availability of suitable cover material. All the potential borrow sites
discussed in Section C are privately owned, therefore, an initial screening of
the owners must be done to determine which are favorable to negotiations for
securing cover materials.
The roadway permitting access to the active fill area should be defined and
constructed. The roadway need not be paved but should be compacted to allow
collection vehicles to pass freely. The filling operation may be started at the
southern end of the fill and proceed toward the northern end. Each cell should-
be filled to about 5 feet high and covered with a 6-inch daily cover of soil.
«r
The final cover should be 2 feet deep and should be of a soil type to permit the
growth of vegetation. Daily and final cover material should be stockpiled at
the site in advance to ensure availability as needed. The diversion ditch
should be constructed around the top of the slope to collect and divert run on.
The gatehouse should be constructed and equipped with a service window for land-
fill users. A fence should be constructed around the periphery of the landfill
to prevent animals from entering the area, to discourage trespassers, and to
delineate the landfill area.
Groundwork. There is a 20-foot drop where the inactive portion of the
landfill meets the active face. From this point to the fenceline at the bottom
of the landfill area, the ground slopes down 35 feet for the remaining 350
feet. This results in a 10 percent slope for the existing ground. The ground-
work should be done in such a fashion as to approximate the existing slope to
reduce erosion, to enhance revegetation, and to avoid an excessively steep slope
on the working face of the final cell. This means that if the finished area is
to adjoin the inactive portion, then the slope line will be 55 feet (35 ft. + 20
ft.) in 350 feet, which results in a 16 percent slope. To accomplish a 10 per-
43
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cent slope the groundwork should be done in a stepwise fashion (see Figure 8)
sloping each 50-foot segment 5 feet downward, at which point a 3-foot drop will
be constructed. These 3-foot drops will not present subsidence or slope
stability problems if proper erosion protection is provided. Several erosion
protection methods are potentially appropriate including riprap, stone-filled
gabions, and sandbags. The selection of a method depends primarily upon an
evaluation of cost, availability, longevity, and aesthetics. For the proposed
3-foot drops, it is estimated that riprap would cost approximately $4 per linear
foot, gabions $6 per linear foot, and sandbags $7 per foot!4 predicated on the
availability of riprap and gabion material (stones, rocks) from the San Juan
River. The engineer chosen by Pagosa Springs to assist in implementing the new
operating plan should make the determination as to the most cost-effective
method of erosion protection for the 3-foot drops.
Six 3-foot drops will compensate for the additional 28 foot drop created by
landfilling and will effectively reduce the slope of the finished surface from
16 percent to 10 percent, (see Figure 7). The proposed terrace arrangement is
a common solution to excessive grades. Although the average grade of the land
surface (after filling) is 16 percent*; the majority of surface area will be
graded to 10 percent. An arrangement of three foot benches spaced 50 feet
apart, whose faces are adequately supported to prevent erosion damage, is one
way to achieve the desired slope. Other configurations and dimensions could be
used, but must be evaluated in terms of a cost comparison. The proposed
arrangement would cost approximately $17,100, or $3,400 each year over five
years (based on utilizing gabions at $6 per linear foot).
G. Review and Comment on the User Charge System
There is a commercial refuse collection firm in Pagosa Springs. The firm
owns one 18 cubic yard rear loading compactor, one 20 cubic yard rear loading
compactor and one 6 cubic yard side loading truck. According to the firm's
owner, Mr. Sam Hi 11,he delivers about 1 truck load (18-20 cubic yard) per day to
the landfill in winter and up to 2 loads per day in summer.
14 Source: Reference 14.
44
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A count of numbers and types of vehicles using the landfill was conducted
during the week of July 21st, 1980, at the landfill. The results are detailed
in Table 12 and show that a total of 115 carloads, 193 pickup truckloads, 7
commercial trash vehicle loads and one oversize vehicle load were counted over
35 1/2 hours that week.
From this data the Town Manager extrapolated at 5 times the 6 days counted
for a 30 day month and estimated the town would realize $2,637 per month if it
charged $1.00 for each carload, $1.50 for each pickup truck load, and $5.00 for
each full trashtruck load.
The Town budget for 1981 projects an income of $26,000 from user fees.
Together with $3,000 from the Town General Fund and an additional $3,000 from
the County and an unappropriated surplus of $600 the expected gross revenues
total $32,600. This equals the town manager's estimate of annual expenditures
to equip and operate the landfill.
The Town initiated a user charge system at the landfill on January 9,
1981. The charges were based on the §bove evaluation of the number, frequency
and method of private and commercial deposits of solid waste at the landfill.
Also impacting the selected charges was the subjective judgement of the indivi-
dual citizen's ability to pay for trash disposal.
TABLE 12
FREQUENCY OF CUSTOMER USE AT PAGOSA SPRINGS LANDFILL
Number of Loads
Pickup Commercial
Date Time Observed Car Truck Trash Truck Dump Truck
7/21
7/22
7/23
7/24
7/25
7/26
TOTAL 6 days
1:00-8:00
12:30-7:00
1:30-6:30
1:30-7:30
10:30-7:00
2:00-5:30
35.5 hours
27
33
22
12
11
10
115
36
20
28
31
58
20
193
1
1 3/4
1
1 1/2
1 3/4
-
7
45
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This report presents a higher estimate of annual operating costs than
projected by the Town. The total cost is estimated to be $42,900. The
difference in the two estimates lies mostly in the cost of personnel.
Using the $42,900 annual cost estimate it will be necessary to increase the
revenues to match the anticipated costs. This report recommends an increase in
user fees as the method of increasing revenues. The following are recommended
revised fees:
Cars $ 1.00
Pickups $ 3.00 (an increase over the $1.50 fee)
Trash Trucks $15.00 (an increase over the $5.00 fee)
The rationale for these new fees is based on subjective judgement that the cur-
rent fee for cars is fair. One car load per week should suffice the average
family. A pickup truck on the other hand can easily carry about three times the
quantity of a car load. One can expect neighbors to pool their trips to the
landfill. If so, three families per pickup truck load per week is believed
reasonable, thus the $ 3.00 fee. The commercial hauler now has about 160 house-
holds from which he collects on a weekly schedule. He delivers on the average 1
1/2 truck loads per day and pays $45 per week fees (1 1/2 loads per day x 6 days
per week x $5 per load). The average household pro rata share of the commercial
fee is ($45 * 160) or about $ .30 per week. This is less than the average
single family carload cost of $1.00 per week discussed above. An increase by
three times the current commercial pick up pro rata share would make the fees
more equitable (3 x $ .30 approximately equals $1.00). This would bring about a
raise in the commercial dumping fee to $15 (3 x $5).
At these new user fees, assuming the same number of car, pickup and trash
truck loads counted by the Town, one can estimate the following weekly revenues:
Weekly Revenue ($)
115 Cars @ $ 1.00 = $115
193 Pickups (3 $ 3.00 = $579
8 Trash/Oversize @ $ 15.00 = $120
$814
46
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The estimated annual revenues (52 x $814 = $42,328) plus the County budget
contribution of $3,000 exceeds the projected annual operational cost of $42,900.
47
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IV. MILL CREEK SITE EVALUATION
A. Introduction
Presently the majority of the solid waste generated in Archuleta County is
disposed of in the Pagosa Springs landfill, two miles outside of the town of
Pagosa Springs. This landfill has been operating many years on an informal
basis and has recently been cited for violating Colorado solid waste disposal
laws. An upgrading program (see Section C) is currently being designed to
upgrade the landfill; however, this will -provide only an interim measure (5 year
maximum) for disposing of solid waste in the County. A new site must be
selected and developed over the next few years before the present site is forced
to close. As a part of the siting effort this report presents an initial study
of the Mill Creek area as a new landfill site (see Figure 8).
The proposed Mill Creek site, which is located in the Northwest quarter of
the Southwest quarter of Section 16, R 1 W T 35N, has a number of factors which
make it a good candidate for further study. First, the land is already owned by
the State which may allow the county to^purchase or lease the land at a signifi-
cant cost savings over privately owned land. Second, the site seems to have
favorable characteristics for a landfill such as (a) its close location to the
Town or user population, (b) the site's easy accessibility from Mill Creek Road,
eliminating the need for new access road construction; and (c) the land is
mildly sloped which should mitigate run-off, run-on, and surface contour prob-
lems. Third, the site is not currently under intensive use and it is currently
used as a grazing area for cattle.
The Mill Creek area was first identified as a possible landfill site in 1973
when Pagosa Springs Mayor James L. Cloman requested permission from the State
Board of Land Commissioners to lease the site for development. At that time the
lease was denied and no further action was taken. However, given the current
condition of the Pagosa Springs Landfill, and its limited future capabilities,
the town has again decided to study the Mill Creek area's potential as a land-
fill. The remainder of this report addresses a number of issues critical to
landfill planning, though no final conclusion is made concerning the suitability
48
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-
10
FIGURE 8. MILL CREEK SITE LOCATION
SCALE 1 • -2 000
-------
of the Mill Creek site for a landfill. No conclusion can be reached until
further studies are done to determine the possible effects of a landfill on the
groundwater of the area.
B. Surface Water. It is very important that a landfill does not contaminate
nearby surface water either by direct run-off into a body of water, or by leach-
ing downward through the soil and working its way laterally through groundwater
into adjacent surface water. A number of environmental and design factors can
be incorporated at the Mill Creek site to minimize the risk of surface water
contamination. First, surface water run-on can be prevented by creating diver-
sion ditches around the landfill where adjacent land is at a higher elevation.
The SCS has, in fact, already constructed several retaining dams on the site to
control erosion. Second, the soil at Mill Creek has been studied in an inven-
tory and evaluation performed recently by the SCS. The survey indicates that
there are predominantly two types of soil in the area being considered for the
landfill. Immediately north of Mill Creek Road - in the valley bottoms - the
soil is Work loam and clay loam (C2-CD) which has been rated as having moderate-
ly slow to slow permeability in the subsoil and substratum. Farther back from
«r
the road in a northerly direction, at higher elevations in the upland areas and
ridgetops, the soil is Yawdim clay loam and clay (CO-CE) which is rated as slow
with respect to infiltration, and which allows for rapid runoff. Under these
conditions, water will be less likely to penetrate the landfill cover and form
leachate. Third, the climate of the Pagosa Springs area will also help prevent
leachate formation and movement. (See water balance discussion in Section III
B). The evapotranspiration rate is 36 inches/year^ which greatly exceeds the
annual precipitation rate of 18.74 inches. Assuming the run-off coefficient to
be quite high (.35), this would allow for only 12.2 inches a year ((1 - .35) x
18.74) to remain on site which could enter the landfill. Most, if not all of
this precipitation will be lost in evapotranspiration, allowing little or no
water to enter the landfill material and form leachate.
An additional concern is the possibility that the site may become flooded,
saturating the enclosed portions of the site and carrying away any loose mate-
15 Source: Reference 13.
50
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rial on the surface. The area proposed for development at Mill Creek has not
been identified as an area of flooding in either the SCS analysis of the area or
the Pagosa Springs "Plan for Progess" therefore the danger of a flood can be
discounted as a problem. While it is true that the bottom bank of Mill Creek is
subject to flooding and high water table, this section has not been considered
for development and would not directly affect the proposed landfill area.
C. Hydrogeology. The proposed landfill area is located in the San Juan Basin.
Mill Creek is characterized by two geologic formations: 1) the Mesa Verde Group
Undivided (composed of buff to gray, cliff-forming sandstones and interbedded
gray shales) (Kmv), and 2) the Mancos Shale (Km), which underlies the Mesa Verde
Group. The actual depth to ground water at the site has not been determined, as
no wells have been drilled. Wells in the sections surrounding the site are of
•
varying depths, but one of the nearest in Sectian 17 (about 1 mile away) is a
dry well that is over 500 feet deep. The newest well is 240 feet deep and water
was reached at 210 below the surface. Assuming that depth to ground water is
fairly deep (an assumption that can only be confirmed by testing) and that
leachate development and movement will be slow to non-existent, operation of a
landfill at this site may be anticipated to have little adverse impact on the
hydrogeology of the area. Further study at the site will be needed to confirm
this assumption. This study should include the drilling of a test well to
determine the level of the ground water table at the site. If it is determined
that the depth of the water table is significantly below grade, then this fact
coupled with the low rainfall in the area may confirm the suitability of the
site.
D. Other Environmental Constraints. The Resource Conservation and Recovery
Act states that the waste management practices should not have an adverse impact
upon prime agricultural land, critial habitat for threatened or endangered
species, archeological or historical artifacts, and the geothermal resources.
Each of these concerns is discussed below. According to officials at the Soil
Conservation Service office in Pagosa Springs, the land in question has not been
classified as prime agricultural land. Therefore, construction at the Mill Creek
site should have no impact on any prime agricultural land.
The "Plan for Progress" for Pagosa Springs lists the wildlife within a ten
mile radius of the Town which includes the Mill Creek area. None of the animals
51
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listed are currently on the Federal or State lists of endangered or threatened
species. Within and around Pagosa Springs vegetation is typical of the Montane
Forest Vegetative Zone . This type of vegetation includes ponderosa pine, moun-
tain mulberry, big sagebrush, serviceberry, and bitterbrush. The more common
grasses include Arizona fescue and slender wheatgrass. Neither the woody or
herbaceous species in the area have ever been listed on the endangered and
threatened species list. From the above data it can be assumed that the Mill
Creek site does not provide critical habitat for any animals or plants which are
threatened with extinction.
The "Plan for Progress" also quotes a letter from the Office of the State
Archeologist which states that there are no known sites of archeological signi-
ficance in the Town or the planning area. Therefore, we assume that no such
sites exist at the nearby Mill Creek Site.
There is no possibility of encountering geothermal resources during con-
struction or operation of a landfill at the Mill Creek site. The Colorado
School of Mines has conducted surveys that indicate the thermal reservoir is
restricted to about 1.5 miles arounderthe Town's Big Spring which does not
include the Mill Creek site.
The area proposed for development is currently used for grazing cattle.
The fencing constructed around the site as well as the activities at a landfill
would preempt this current use. However, upon final closure of this site, the
area could be restored to allow the resumption of cattle grazing. The proposed
landfill design is based on grazing as the final beneficial use of the property.
E. Availability and Suitability of Cover Material. In order to operate a land-
fill in the cheapest and most efficient manner, it is desirable to have suffi-
cient cover material available on site to provide for daily and final cover.
The Mill Creek site has two predominant types of soil, C2-CD and CO-CE. As
previously discussed, the SCS Study has evaluated each with respect to its suit-
ability as cover material (see Table 5). The C2-CD has been rated as good cover
material. The top three (3) feet are rated as best for final cover material.
CO-CE is rated poor as final cover but adequate for daily cover. Each of these
soil types covers about one half of the total area we have assumed will be
52
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available for use. We have assumed that the entire Northwest quadrant and a
small amount of the Southwest quadrant (North of Mill Creek Road) of Section 16
would be available for use. However, the original request to lease this site in
1973 stated that 40 acres would be requested and 20 developed. Therefore, it
was assumed that a similar site would be developed today, though enlarged
slightly for a longer life of the landfill.
The analysis of the adequacy of land area in Section F below identifies a
need for a landfill about 30 acres in size that would operate for 25 years.
Cover material for this 30 acres could largely be attained by excavating 3 feet
of soil from the C2-CD area (roughly 20 acres) of the landfill, which would
provide for 30 acres of 2-foot final cover. Daily cover material is available
at the site in abundance, as only two 6-inch layers are required over the 30-
acre site. The landfilling method proposed in Section F includes two 6-inch
layers of soil fill in the design, one at the bottom of the landfill and anoth-
er layer on top of the first cell for a total of 12 inches of poorer quality
fill required throughout the site. The existence of on-site cover material of
adequate volume to meet the requirements of the landfill provides strong sup-
port for developing this site. It till save costs over an alternative site
without onsite cover.
F. Land Area. To determine if adequate land area is available at Mill Creek,
estimates of the waste volume generated over a period of time, and a prelimi-
nary landfill design must be prepared for the site. The volume of waste we have
projected to be generated in the area served by the landfill is based on waste
generated per person per day, population using the site, and a compaction ratio
for the waste. A production rate of 4 Ib/capita/day was derived from review of
a study16 which estimated waste generation rates ranging from 3.36 to 3.76
lb/capita/ day. This rate includes commercial/institutional wastes in addition
to residential wastes. We have adjusted that estimate to 4 Ib/capita/day to
account for future increases which may occur and allow us to use one
16 Source: Reference 11.
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production value through the life of the site. This rate is, in part,
influenced by the expectation of increased tourist activity in the future.
Population figures were obtained from the "Plan for Progress" for the
years 1985-2000 for the entire County. We chose to include the entire county
in the calculations, even though a small community at Arboles has its own
landfill, because we felt the Arboles landfill would not make a significant
difference in our calculations of the landfill requirements for Archuleta
County. Beyond the year 2000, population figures were extrapolated forward for
the years 2005 and 2010. The year 1985 was selected as the starting date
because it is expected that the Pagosa Springs Landfill will begin closure at
that time as stated in the landfill compliance schedule prepared by the Town.
A final assumption necessary to determine waste volume is the compaction
rate of the material once it is disposed in the landfill. Average compaction
rates of 800 Ib/cubic yards are attainable without special equipment. (This
figure was obtained from the "Sanitary Landfill Design and Operation" document
prepared for EPA). The activity of a bulldozer onsite should compact the waste
to this volume. The assumptions ant calculations used to derive the waste
volume are shown below.
Calculations
(1) Solid 'waste generation rate = 4 Ib/person/day
(2) Average population over 25 year period = 9,500
(3) Pounds of waste generated per day
= 9,500 x 4
= 38,000 Ib/day
(4) Compaction ratio = 800 Ib/yd3
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(5) Volume of Waste disposed per day
= 38,000 * 800
= 48 yd3/day
(6) Volume to be disposed per year
= 48 x 365
= 17,500 yd3/year
(7) Volume to be disposed in 25 years
= 17,500 x 25
= 438,000 yd3/25 years
In the 25 year period from 1985-2010 the county will generate and must
dispose of approximately 438,000 cubic yards of solid waste.
To dispose of this waste the following general landfill design has been
developed. (Figure 9 schematically illustrates the area method of sanitary
landfilling which is recommended for the Mill Creek site.) The waste will be
placed in two 4 1/2 foot thick cells separated by a 6-inch daily cover. Under-
neath the bottom cell would be 6 inches of in-situ clayey, relatively imper-
meable soil to act as a liner. Two feet of final cover will be placed on top of
the second cell. Given the waste volume, and assuming the landfill structure
defined above is developed, the area required to dispose of the waste can be
calculated as follows:
438,0000 x 27 = 11,826,000 cubic feet of refuse
11,826,000 -s 9 = 1,314,000 square feet of space needed
1,314,000 * 43,560 = 30 acres of land
This is equal to an area approximately 1,150 feet by 1,150 feet.
Based on this preliminary estimation of waste volume and landfill design,
it appears that the Mill Creek site, if developed properly, would be adequate to
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FIGURE 9. TRENCH AND AREA METHODS OF SANITARY L A N D F I L L I N Qd
Source: Reference 2.
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act as a landfill for Archuleta County over the next 25 years. It is important
to remember that the basic assumption made in these calculations is that the
landfill is desired to be somewhat close to the areal size originally proposed
in 1973. The landfill's life could be extended beyond 25 years if the landfill
is built-up higher than the suggested two, 4 1/2 - foot lifts.
G. Estimated Costs. The costs of developing the Mill Creek site into a
landfill can be broken down into three separate areas. First, the cost of the
land itself must be considered; second, initial site development costs need to
be calculated; and third, the annual operating costs for a landfill need to be
estimated. All capital costs are amortized over a 10-year period in this cost
analysis.
Land Cost, The value of the land at the Mill Creek site has been estimated
to be between $1,200 and $1,500 per acre. This estimate is based on conversa-
tions with a local real estate agency and the County Land Board. At that price,
buying the Mill Creek site would prove a burdensome expense to a County such as
Archuleta.
r
There is an alternative to buying the land. The land is currently leased
by the State for grazing. If the County can arrange to lease the site at the
same fee, a substantial savings may accrue over the life of the facility. At
the end of the period of its life as a landfill, Mill Creek could be returned to
its former use as grazing land once final closure activities and revegetation
are completed.
Site Development Costs. Site development costs are characterized as those
costs incurred when preparing the site for use as a landfill. These costs are
further distinguished by the requirement that they be paid as the necessary
goods and services are acquired. Table 13 illustrates the site development
costs.
The entire site must be fenced, therefore, the fencing estimate includes the
entire forty acres proposed for the site. A gravel road must be constructed
back into the site. The estimated $20,700 to construct the gravel road (includ-
ing the subbase) was derived from the 1976 Means Cost Data and updated to 1980
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TABLE 13
SITE DEVELOPMENT COSTS (MILL CREEK SITE)3
Item
Fenci ng
Diversion Ditch-
ing Road Construc-
tion:
30 feet wide
2,640 feet long
9 inches deep
Subbase
Road
Groundwater monitor-
ing wells
Engineering fee
Amortized Site Develop-
ment Costs (12%
interest, 10 years)
Unit Cost ($)
3.30/linear foot
2.70/linear foot
0.90/yd2
1.45/yd2
1,170/well
r
2 wel1s
Quantity
4,600 ft. $15,200
1,100 ft. 3,000
8,800 yd2 7,900
8,800 yd2 12,800
2,300
4,100
Total $45,300
$8,000
a Costs were derived from the 1979 Dodge Guide (Ref. 5) and the
1976 Building Costruction Cost Data Handbook (Ref. 3). All
costs were converted to 1980 dollars using the 1980 Product
Price Index (Ref. 9).
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cost of the work crew, materials (gravel) and the machinery involved. An
engineering fee of $4,100 is included, as professional engineering services
should be procured to assist the town in developing the site. Activities which
can be undertaken during operation of the site, such as stock piling cover
material, are not included as site development costs. They are included as part
of the annual operating costs. Total site development costs will be
approximately $45,300.
Capital and Annual Operating Costs. Table 14 is an itemized list of the
capital and operating costs associated with the Mill Creek Landfill. Capital
costs are incurred for such items as a crawler dozer, operator building,
portable sanitation facilities, office equipment, etc. The total capital cost
of $59,350 was amortized over a 10-year period using the capital recovery factor
(CRF) for a uniform series for 10 years at 12 percent interest (0.177).
Although the Mill Creek site has a projected life of 25 years, a 10-year period
was used to develop the capital and operating cost, as many items have a life-
span of 10 years, and 10 years is a more reasonable planning horizon than 25
years.
r
Annual costs include a full-time operator, office supplies and expenses,
fuel oil, and gravel. The hourly wage (including fringe benefits) for the
equipment operator was taken from the Dodge Guide (Ref. 5) for the City of
Denver; the wage rate was scaled down 25 percent to reflect reduced rural wage
rates. For the daily and final cover it was assumed that one twenty fifth of
the total cover required in the 25 year life of the site would be utilized each
year. Additionally, revegetation is assumed to occur at a constant yearly rate
over the life of the landfill. Groundwater monitoring costs includes taking 2
samples at each of two wells once per year. Analyses would be performed for pH,
BOD, dissolved solids and one or two additional parameters.
The annual operating cost projected for the Mill Creek site is $26,410.
Adding in the amortized site development cost of $8,000 and the amortized
capital cost of $10,510 results in a total annual cost of $44,920. Based on an
average generation rate of 19 tons per day, the disposal cost per ton equals
$6.48.
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TABLE 14
MILL CREEK LANDFILL COSTS a
Item
CAPITAL COSTS
Crawler dozer*5
Operator building
Portable sanitation
Office equipment
Signs and posts,
hand tools, fire
extinguisher
Unit Cost ($)
53,000
5,000
500
500
350
Quantity Total Cost
1 each
$53,000
5,000
500
500
350
Amortized Capital Cost
Total Capital Cost $59,350
(10 years 12% interest) $10,510
ANNUAL COSTS
Equipment operator
(including fee
col lection)
Office supplies,
printing, telephone,
and uti1ities
Fuel Oil
Gravel
Cover material
Final cover
Daily cover
Revegetation 1
Groundwater monitoring
(includes 2 samples
and analyses at 2
wells each year).
8.48/hr.
1,400
1,560
500
I
0.60/yd3
0.60/yd3
,170/acre
500/well
2,080 hr./year $17,640
1,400
1,560
500
96,750/25 years
24,450/25 years
30 acres/25 years
2 welIs
Total Annual Cost
Plus Amortized Capital Cost
2,320
590
1,400
1,000
$26,410
$10,510
TOTAL $36,920
a Cost were derived from the 1979 Dodge
1976 Building Construction Cost Data
costs were converted to 1980 dollars
Price Index (Ref. 9).
Guide (Ref. 5) and the
Handbook (Ref. 3). All
using the 1980 Product
The bulldozer life expectancy is 12,000
use of four hours per day the dozer will
years .
hours. At a rate of
last approximately 12
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H. Accessibility. The Mill Creek site is about four miles out side of the
center of Pagosa Springs. It has been estimated that 85 percent of the
population of Archuleta County lives within 10 miles of the town, so the site
should be within relatively short hauling distance for most residents. In
comparison, this site is only slightly farther from the center of town than the
present dumpsite.
A key to designing an effective landfill is to ensure that it is accessible
to the user population and all types of traffic. The road leading to the site
(Mill Creek Road) is constructed of gravel and will probably be sufficient to
bear the landfill traffic without incurring upgrading costs. It appears to be
both wide and durable enough to handle truck traffic. It will be necessary to
construct a road approximately 1/2 mile long to allow access to the back of the
dumping area.
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REFERENCES
1. Briscoe, Maphis, Murray, and Lament, Inc. Plan for Progress, Pagosa
Springs. Colorado. June, 1979.
2. Brunner, D.R., and Keller, D.J., Sanitary Landfill Design and
Operation, U.S. Environmental Protection Agency, Report SW-65ts, 1972.
3. Building Construction Costs Data Handbook, 34th Ed., Robert Snow Means
Co., Inc., 1976.
4. Dehn, W.J. Solving the Abandoned Car Problem in Small Communities,
U.S. Environmental Protection Agency, 1974.
5. Dodge Guide to Public Works and Heavy Construction Costs, McGraw-Hill
Information System Co., New York, 1979.
6. Fenn, D.6., et al., Use of the Water Balance Method for Predicting
Leahate Generation fronfSolid Waste Disposal Sites, U.S. Environmental
Protection Agency, Report SW-168, Cincinnati, Ohio, 1975.
7. Galloway, M.J., Hydrogeologic and Geothermal Investigations of Pagosa
Springs, Colorado", Special publication 10, Colorado Geological Survey,
Department of Natural Resources, Denver, 1980.
8. Lutton, J.R., Evaluating Cover Systems for Solid and Hazardous Waste,
U.S. Envi ronmental Protect ion Agency, Report SW-867, C i n c i n n a t i, Ohio ,
1980.
9. Product Price Index for Finished Goods, 1980.
10. Shaw, D.L., The Farmstead Windbreak, Colorado State Forest Service,
Fort Collins, Colorado, 1974.
11. Smith, F.A., Comparative Estimates of Post-Consumer Solid Waste, U.S.
Environmental Protection Agency, Report SW-148, 1975.
12. Steven, T.A., Lipman, P.W., Hail, W.J., Barker, F., and Luedke, R.G.S
Geologic Map of the Durango Quandrangle Southwestern Colorado, U.SC
Geological Survey, Miscellaneous Investigations Seri es, Map 1-764,
1974.
13. Thornthwaite, C.W. and Mather, J.R., Instructions and Tables for
Computing Potential Evapotranspiration and the Water Bal ance,
Publ i cations Tn Climatology VX, No.T~, Drexel Institute of Technol ogy,
Centerton, N.J., 1957.
14. Engelsman, C., 1981 Heavy Construction Cost File, Van Nostrand
Reinhold Co., NY, NY, 1981.
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APPENDIX A
Soils Maps
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CITY
LANDFILL
AREA
SCALE 1'-.28 MILES
FIGURE A-1
SOILS MAP, OLD LANDFILL AREA
A-1
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SCALE 1'-.25 MILES
FIGURE A-2
SOILS MAP, MILL CREEK SITE AREA
A-2
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