HomeMy WebLinkAbout921316.tiff DOYLE, LEIN, OTIS, FREY, HELLERICH LAZAR
ATTORNEYS AT LAW
I
RICHARD N.DOVLE SUITE 300 DENVER METRO
HENRY C.FREY AFFILIATED NATIONAL PLAZA (303)659-7576
THOMAS E.HELLERICH 822 7th STREET ,,.., - ri .....,
ROGER A.KLEIN GREELEY,COLORADO 80631 - !I FAX
MCHAEL A.LAZAR (303)953-6712
FRED L OTIS (303)35'-6700 I,....i,;
1 •
May 4 , 1992
Chuck Cunliffe
Weld County Planning Director
915 10th Street
Greeley, CO 80631
RE: Denver Regional Landfill South - SUP-400/Laidlaw Waste
Systems Colorado, Inc .
Dear Mr. Cunliffe:
Attached please find a letter dated May 4 , 1992 from Ben Doty of
Doty & Associates which compares the 1979, 1982 , 1988 and 1991
applications with regard to Special Use Permit - 400 . Hopefully
this information will assist you and the County Commissioners in
evaluating the need for an Amendment to the Special Use Permit.
Sincerely,
Fred L. Otis
Attorney at Law
FLO:cas
Enclosure
c: Weld County Commissioners
Weld County Attorney
Rick Hoffman
Scott Schreiber
04 6
af� I i 7 921316
i3LOY-I.S
DOTY & ASSOCIATES
ENVIRONMENTAL,GROUND-WATER AND WASTE MANAGEMENT ENGINEERS
20011 GOLDEN GATE CANYON ROAD
SUITE 100
GOLDEN, COLORADO 80403-8125
TELEPHONE: (303)279-9181
FAX: (303)279-9186
May 4, 1992
1202-05
Mr. Rick Hoffman
Division Manager/Landfill
Laidlaw Waste Systems, Inc.
P.O. Box 320
Erie, Colorado 80516
Subject: Need for Amended Special Use Permit
Denver Regional Landfill (South)
Laidlaw Waste Systems, Inc.
Dear Mr. Hoffman:
This letter evaluates the need for an amended Special Use Permit
(SUP) with Weld County for the Denver Regional Landfill (South) .
HISTORICAL DESIGNS
The south site has been operated under three operations plans;
a fourth has recently been approved by the Colorado Department
of Health. The various plans are described below and, in
summary, are as follows.
Design 1979 1982 1988 1991
Fill Area (acres) 107 148 148 114
Maximum El . (ft) 5220 5240 5240 5334
Est. Volume (M yd3) 1 4 . 2 16. 3 16. 3 23 . 2
Liner Thickness (ft) 1. 0 1. 0 0. 5 3 . 02
Leachate System None 3 wells 4 wells Full3
Cover Thickness (ft) 2 . 0 2 . 0 3 . 5 4 . 0
Env. Monitoring None Yes Yes Yes
Hours (hrs/days) 4 8/6 8/6 16/7 15/6
Amended SUP req'd. Original No No ?
Mr. Rick Hoffman
Page 2
May 4, 1992 Doty & Associates
1979 Operations Plan
The 1979 design (Nelson, 1979) was permitted with Weld County
under SUP #400. The fill was designed as a ring which excluded
the severe subsidence hazard area in the center of the property.
The north and south portions of the fill rose to an elevation of
5220 feet; the western edge was sixty feet lower (elevation 5160
feet) . To the best of my knowledge, an excavation plan was
never developed; however, sufficient soil was to be excavated
for daily and intermediate cover as well as two feet of final
cover. Prior to filling, the native soils were to be scarified
and recompacted to provide a one-foot thick liner.
Hours of operation were eight hours per day, six days per week.
1982 Design
The 1982 design (Nelson, 1982) was permitted with Weld County
under SUP 534 : 82 : 49 . The intent of the 1982 design was to close
the Pratt property in order to promote long-term stability and
minimize infiltration of incident precipitation. As part of the
new design, the geometry of the south site fill was also changed
so that the two fills would join smoothly.
The major design changes consisted of increasing the total area
on the south site to be covered by refuse to 148 acres (from 107
acres) and increasing the highest elevation to 5240 feet (from
5220) . Refuse was to be placed over the entire 148 acres as a
single fill. An excavation plan was prepared in order to
provide for daily and intermediate cover as well as two feet of
Notes to table on page 1:
1. Volume is in million cubic yards and is estimated because
the 1979 excavation plan is not available and as-built
records were not kept prior to 1988 . Volume includes final
cover.
2 . 1991 liner consists of three feet of compacted clay
overlain by a 60 mil HDPE geosynthetic membrane.
3 . 1991 leachate collection system consists of a complete sand
drainage layer (12" thick) with laterals and headers
leading to four leachate collection sumps.
4 . Anticipated hours of operation are given above as hours per
days/days per week. The 1991 design allows for 24 hour per
day, 7 day per week operation.
Mr. Rick Hoffman
Page 3
May 4 , 1992 Doty & Associates
final cover. :Prior to filling, the native soils were to be
scarified and recompacted to provide a one-foot thick liner. In
addition, the design provided for three wells to detect and
collect leachate; the wells were located at low points in the
liner. Also, a perimeter ditch system to collect leachate was
designed.
Requirements for environmental monitoring (ground-water and
subsidence monitoring) were added for the first time.
Hours of operation were eight hours per day, six days per week.
1988 Design
She 1988 design (IC, 1988) was prepared to fulfill some of the
requirements of the Certificate 9f Designation and SUP #490
transfer from Colorado Landfill, Inc. , to Laidlaw Waste Systems,
Inc. The 1988 design modified the orientation of the ridge
along the top of the designed final contours; otherwise, the
fill geometry and total area to be covered by refuse are very
similar to the 1982 design.
A new excavationplan was prepared for areas not already covered
by refuse in order to provide sufficient soil for daily, inter-
mediate, and final cover. The final cover thickness was
increased from two feet to 3 . 5 feet (3 feet of compacted clayey
soil and 6 inches of topsoil) . Prior to filling, the native
-materials (soil or bedrock) were to be scarified and recompacted
to provide a 6-inch thick liner (instead of the one foot thick
liner previously required) . In addition, the design provided
for four leachate detection/collection wells located at low
points in the liner (as opposed to the three wells planned in
the 1982 design) . The perimeter ditch system to collect
leachate was removed from the design.
The 1988 design included specifications for environmental
monitoring (ground-water, leachate, subsidence and explosive gas
monitoring) .
Hours of operation were sixteen hours per day, seven days per
week (as opposed to eight hours per day, six days per week) .
1991 Design
The 1991 design (Golder, 1991) is intended to bring the facility
into compliance with the new federal regulations (Subtitle D of
-RCRA) . The total area to be covered by refuse is similar to
that of the 1988 design (smaller because the property line
setback has been increased from 50 to 100 feet and a sedimenta-
Mr. Rick Hoffman
Page 4
May 4, 1992 Doty & Associates
tion pond will be constructed in the southwest corner of the
site) .
The key features of the 19-91 design are a three foot thick
compacted clay liner overlain by a 60 mil HDPE geosynthetic mem-
brane. The membrane is covered with a 12-inch thick drainage
layer which leads to four new leachate collection sumps (one of
the 1988 detection/collection wells has already been installed) .
In addition, the facility will be capped with a final cover
system consisting of four feet of soil. In order to make these
improved environmental controls economically feasible, the
-geometry of the fill was changed and the highest portion of the
fill raised to 5334 feet. A new excavation plan was prepared
-for areas not already covered by refuse in order to provide the
soil needed for the various covers.
The 1991 design (like the 1988 design) includes specifications
for environmental monitoring (ground-water, leachate, subsidence
-and explosive gas monitoring) .
Hours of operation are anticipated to be fifteen hours per day,
six days per week (although twenty-four hours per day, seven
days per week is the requested allowable schedule) .
COMPARISON OF DESIGNS
Each of the designs has made some changes to the operational
features at the site. The key features of the designs are
summarized on fable 1. Probably the most significant changes
occurred with the 1982 design when the fill was expanded to
cover the entire site and the disposalvolume increased from 4 . 2
to 16. 3 million cubic yards. The 1982 design also provided for
a leachate collection system and environmental monitoring. A
special use permit was issued which obliquely authorized this
change (SUP #534 : 82 : 49) ; however, the permit really dealt with
the adjoining Pratt property.
The 1988 design was very similar to the 1982 design. The only
differences involved a slight change to the overall geometry of
the fill, a thinner liner, a thicker final cover, and an
additional leachate detection/collection well. This design was
reviewed by the County and SUP #400 (showing the 1979 design)
was transferred to Laidlaw. Apparently, the County did not
consider the design changes between 1979 and 1988 to be material
deviations (see more on this topic below) .
The 1991 design is actually rather similar to the 1982 and 1988
designs, in spite of the fact that the fill will extend to
elevation 5334 . The total site capacity is increased from 16. 3
Mr. Rick Hoffman
Page 5
May -4, 1992 Doty & Associates
to 23 . 2 million yards (a much less significant increase than the
increase from 1979 to 1982) . This capacity increase is rather
small given the height increase; the rel-atively small increase
results from a reduced acreage to be covered by refuse (area is
sacrificed for a sedimentation pond and an increased property
line setback) . In addition, the excavation is limited to areas
not already covered by refuse (this limits the volume of cover
soil that can be developed on site) . The other changes are
consistent with earlier modifications, which generally tend
toward more and better environmental. controls.
NEED FOR AMENDED SPECIAL USE PERMIT
The need for an amended special use permit hinges on whether the
1991 design constitutes a "material deviation" from the 1979
permit; however, material deviation is not specifically -defined
in the County regulations. The use of the property has been
consistent -over the years and will not change under the 1991
design. Thus, the only change that might constitute a material
deviation is the fill -geometry change. However, SUP #400
clearly states in Note 8 that the final geometry of the fill
depends on the availability of suitable material for use as
cover and that the final geometry is likely to vary from the
contours shown -on the permit.
I trust that this material and discussions meet your needs.
Please call if you have questions or need additional informa-
tion.
Sincerely,
DOTY & ASSOCIATES
Benjamin P. =Dot , P.T.
Mr. Mick Hoffman
Page 5
May A , 1992 Doty & Associates
REFERENCES
Golder, 1991, Design and Operations flan for the -Denver _Regional
Landfill (South) , Weld County, Colorado, prepared for
Laidlaw Waste Systems (Colorado) , Inc. , prepared by Golder
Associates Inc. , Project No. 913-232-4 . 0D3 , September.
It, 1958 , Laidlaw South Landfill, Design and Operations Plan,
prepared for Laidlaw Waste Systems, Inc. , prepared by
Industrial Compliance, Ino. , IC Project No. 2-1803 , March
28 .
Nelson, 1579, Operations Plan for Southwest Weld Oounty Land-
fill, prepared for Colorado landfill, anc. , prepared by
Nelson Engineers, September 24 .
Nelson, 1982 , Operations Elan for Platt Property Landfill,
prepared for Colorado Landfill, Inc. , prepared by Nelson
Engineers, Project No. 2017, November 12 .
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