HomeMy WebLinkAbout962361.tiff STATE OF CO LORADO
Roy Romer,Governor F
Patti Shwayder,Executive Director ti4;0
Co,_
Dedicated to protecting and improving the health and environment of the people of Colorado N�-
ra
HAZARDOUS MATERIALS AND WASTE MANAGEMENT DIVISION ** -�f
4300 Cherry Creek Dr.S. 222 S.6th Street, Room 232 "1816.
Denver,Colorado 80222-1530 Grand}unction,Colorado 81 5 01-2 768
Phone(303)692-3300 Phone 1303)248-7164 Colorado Department
Fax(303)759-5355 Fax(303)248-7198 of Public Health
July 29, 1996 and Environment
Rick Hoffman
Laidlaw Waste Systems (Colorado) Inc.
1441 Weld County Road 6
P.O. Box 320
Erie, Colorado 80516
RE: Modifications to Design and Operations Plan
Denver Regional Landfill (South)
Weld County
Dear Mr. Hoffman:
The Solid Waste Unit of the Hazardous Materials and Waste Management Division (the
Division) has reviewed the document entitled "Modifications to Design and Operations Plan for
the Denver Regional Landfill (south) Weld County, Colorado" prepared by Golder Associates
Inc., dated April 1996. The document was reviewed to determine its compliance with the
requirements set forth in the Solid Wastes Disposal Site and Facilities Act, CRS, 30-20-100 et
seq. and with the regulations promulgated thereunder, 6 CCR 1007-2 (the Regulations). The
proposed modifications to the facility's design and operations plan include: 1) an addition of a
3.5 acre composting facility, 2) the construction of a perimeter berm, 3) relocation of the
sediment basin and 4) combining Cells C and D into one cell. At this time, the state does not
have approved composting regulations. However, in all likelihood, the draft composting
regulations will be adopted by the Board of Health in 1996. Therefore, the Division believes
it is appropriate to utilize the draft regulations for review of the proposed composting operation.
The Division has the following comments regarding the proposed changes:
Composting Facility
1. Provide a detailed map view of the composting area, the figure submitted is difficult to read.
Of specific interest is the construction of the runoff collection trenches. The figure should detail
direction of drainage, relative elevations, connection to the greater site-wide runoff collection
trenches.
2. A commitment is needed to remove leachate from the collection trenches in seven (7) days
or less as a form of vector control.
3. Please state what precipitation event the runoff collection system is designed to contain and
manage. With what frequency can a discharge to the sedimentation basin from the comrostin_
facility be expected? EXHIBIT
962361 I a
Mr. Rick Hoffman
July 29, 1996
Page 2
4. Assurance is needed, based on site specifics and design considerations, as to the potential this
operation has for serving as a source of (any) threat to groundwater resources.
5. Please provide a flow chart detailing how material will be handled from the time of receipt
to the time of removal for sale or use.
6. The state's Water Quality Control Division must be notified regarding the proposed
composting operation, to determine if modifications to the facility's stormwater discharge permit
are necessary.
Containment Berm
1. Settling of the waste within the landfill may create depressions where the top of the
compacted clay cap intersects the containment berm. These depressions could accumulate
surface water or affect the structural integrity of the clay cover. Documentation must be
provided which shows whether or not surface depressions may occur and explain the effect this
settlement may have on the structural integrity of the clay cover.
2. The containment berm is proposed to be constructed with an internal clay wall that will be
supported from the outside with compacted backfill while the inside will be supported by a
combination of compacted backfill and compacted refuse. There is some concern that the
difference in densities of these materials (compacted trash and compacted backfill), along with
differential settling on either side of the clay wall, may cause the clay wall to move during the
post-closure period. Documentation must be submitted which addresses the issue of potential
settlement and movement associated with the containment berm. If calculations show that
movement and/or settlement will occur, describe how this may affect the final cover integrity
and performance of the surface water run-off structures.
3. Please describe in detail the phases of construction that will be necessary to build the
containment berm.
Cell C Design Changes
1. On page 19 of the facility's September 1991, Design and Operations Plan, it states that the
coal mine workings in the area of the landfill may create subsidence of up to 2' within the
landfill with a maximum slope change of 1.6%. It also states that this subsidence will not
damage the composite liner system which can sustain uniaxial strains of at least 10%, and that
positive drainage to the sump will not be compromised as a 4% grade has been incorporated in
the liner design.
Please explain whether or not this subsidence has the potential to "backtilt" the leachate drainage
system if the base grade is decreased from 4% to 2%, or if potential subsidence could have any
other detrimental effects on the integrity or performance of the liner and leachate collection
recovery system. In addition, submit an analysis of leachate flow travel time assuming a 2'
subsidence occurs under cell C, and the design base grade of 2%, has been decreased by an
appropriate amount.
962351
Mr. Rick Hoffman
July 29, 1996
Page 3
2. The leachate flow analysis in the sand drainage layer assumes an additional 1' of head within
the sand layer. The leachate calculation should evaluate leachate that flows directly on top of
the composite liner using the base grade of the waste cell. However, it would be appropriate
to calculate leachate flow analysis using a head value as determined from HELP runs for this
facility's design.
General Comments
1. Any location where a perimeter channel is located close enough to the composite liner and/or
waste to cause erosion or stability problems must be lined with rip-rap or other appropriate
armor to protect the integrity of the landfill through the post-closure period. Based upon recent
on-site observations, certain segments of the southwest perimeter channel are experiencing
excessive erosion.
2. After reviewing the surface water channel data listed on Table 2, it appears, based on shear
stress values, that "armored" lining for channels B8A and B-1 may be more appropriate, then
the proposed grass lining. Please provide justification for the lining type chosen for the
aforementioned channels.
These conclude the Division's comments regarding the proposed modifications to the above
referenced facility's design and operations plan. The Division is unable to complete its review
until these issues have been adequately addressed.
If you have any questions regarding this letter, please contact me at (303) 692-3437.
Sincerely,
Roger Doak
Geologist
Solid Waste Unit
Compliance Program
cc: Dean Rector, Golder Associates
Trevor Jiricek, Weld County Health Department
sw/wld/las 3
962361
Golder Associates Inc.
200 Union Boulevard.Suite 500 Golder
Lakewood.CO USA 80228 ASSOCIateS
Telephone(303)980-0540
Fax(303)985-2080
August 13, 1996 Our Ref: 953-2893.003
=;a , +pis+ P6ann ng Dept.
Colorado Department of Public Health and Environment
HMWMD
4300 Cherry Creek Drive South NOV 0 1 1996
Denver, Colorado 80222-1530 4 D,
Attention Mr. Roger Doalc. Geologist
RE: RESPONSE TO CDPHE COMMENTS, DENVER REGIONAL
LANDFILL(SOUTH), WELD COUNTY, COLORADO
Dear Mr. Doak:
On behalf of Laidlaw Waste Systems, Inc. (Laidlaw) Golder Associates Inc. (Golder) has
prepared this response to comments prepared by the Colorado Department of Public Health
and Environment (CDPHE) pertaining to our report entitled "Modifications to Design and
Operations Plan for the Denver Regional Landfill, Weld County, Colorado," (the design
report) dated April 1996 and the accompanying design drawing package entitled "Denver
Regional Landfill, Weld County, Colorado, Design Improvements," (the design drawings)
dated February 1996. The CDPHE comments were presented to Mr. Rick Hoffman of
Laidlaw in a July 29, 1996 letter.
The following presents the CDPHE comments immediately followed by the response.
COMPOSTING FACILITY
Comment No. I
Provide a detailed map view of the composting area, the figure submitted is difficult to
read. Of specific interest is the construction of the runoff collection trenches. The figure
should detail direction of drainage, relative elevations, connection to the greater site-wide
runoff collection trenches.
Response No. 1: A detailed (close-up) drawing of the compost area is attached as Figure
1. The detail of the perimeter surface water collection channel is provided on Detail 3 of
Figure 11 of the design drawings. The surface water control channels are discussed in the
design report. E
XHIBIT
9623tfl !
OFFICES IN AUSTRALIA.CANADA.GERMANY. HUNGARY ITALY,SWEDEN UNITED KINGDOM, ULu31/11E3
August 1996 2 953-2893.003
As shown on Detail 3, Figure 11, the channels are V-shaped, with a typical depth of 2.5
feet with 3H:1V sideslopes, resulting in an approximate crest-to-crest width of 15 feet. It
is envisaged that the perimeter channels will be constructed such that the crest maintains a
constant elevation. This will cause the channels to vary in depth and to act as a "moat,"
thus allowing flow to discharge from the channels only when full. Because of these
relatively flat grades, the channels will be subject to minimal, if any, erosion problems.
As shown on the attached Figure 1, the compost perimeter channels are connected to a
discharge channel leading to the sediment control structure. At this intersection location,
the perimeter channel will be constructed with a lowered crest, causing discharge to flow
down the connecting channel. However, if discharge were to occur at other locations, all
flow would be intercepted and directed to the sediment control channel (see attached Figure
1 and Figure 2 of the design drawings).
Based on the previously discussed dimensions and an approximate length of 1,700 feet
(Figure 1 attached), the perimeter channel is capable of storing approximately 32,000 cubic
feet of water prior to discharge into the sediment control structure. The compost pad has
an approximate area of 150,000 square feet. Therefore, the channel can accommodate a
precipitation event of approximately 2.5 inches over the pad, equivalent to a 5-year, 24-hr
storm event (Procedures for Determining Peak Flows - Supplement to Technical Release
55, March 1984, Soil Conservation Service).
Comment No. 2
A commitment is needed to remove leachate from the collection trenches in seven (7) days
or less as a form of vector control.
Response No. 2: As part of the operation of the compost facility, Laidlaw will remove
any accumulated water in the compost perimeter channels within seven working days,
weather permitting. The removed water will be properly disposed of or reused.
Comment No. 3
Please state what precipitation event the runoff collection system is designed to contain and
manage. With what frequency can a discharge to the sedimentation basin from the
composting facility be expected?
Response No. 3: See response to Comment Nos. 1 and 2
Comment No. 4
Assurance is needed, based on site specifics and design considerations, as to the potential
this operation has for serving as a source of(any) threat to groundwater resources.
2893R5P.000 Golder Associates 962361
August 1996 3 953-2893.003
Response No. 4: As discussed in the design report the following design and operational
features will be incorporated into the compost facility:
• The compost facility will only accept garden and yard leaves, tree trimmings, etc.
wastes;
• The site is located on a topographic high, thus eliminating run-on to the facility;
• The operations will occur over an engineered soil liner which will be a minimum of 6-
inches thick and constructed with an in-place hydraulic conductivity no greater than
1x10-5 cm/sec;
• The facility is located at least 20 feet above groundwater; and,
• The natural occurring materials beneath the site consist mainly of low-permeability
shales and claystones.
These factors, combined with the operational practices described in the design report, will
minimize the potential for groundwater impacts from the anticipated non-hazardous
leachate generated from the natural garden and yard wastes composted at the facility.
Comment No. 5
Please provide a flow chart detailing how material will be handled from the time of receipt
to the time of removal for sale or use.
Response No. 5: A flow chart has been provided on the attached Figure 2.
Comment No. 6
The state's Water Quality Control Division must be notified regarding the proposed
composting operation, to determine if modifications to the facility's stormwater discharge
permit are necessary.
Response No. 6: Upon approval of these permit modifications the storm water
management plan will be revised to reflect the modifications. A copy of the design
drawings, design report, and this response to comment letter will be forwarded to the
Water Quality Control Division.
CONTAINMENT BERM
Comment No. 1
Settling of the waste within the landfill may create depressions where the top of the
compacted clay cap intersects the containment berm. These depressions could accumulate
surface water or affect the structural integrity of the clay cover. Documentation must be
2893RSP.DOC Golder Associates
August 1996 4 953-2893.003
provided which shows whether or not surface depressions may occur and explain the effect
this settlement may have on the structure integrity of the clay cover.
Response No. 1: The intersection of the final cover and the containment berm is the same
detail as the intersection of the final cover to the existing top of liner slope, or perimeter
corridor. As shown on Detail 1, Figure 11 and Detail 1, Figure 12 of the design
drawings, the critical portion of the containment berm and the "internal clay wall" are
founded directly on the perimeter corridor. The final cover intersects the containment
berm in a vertical plane above the perimeter corridor. No waste is located immediately
beneath this intersection. Therefore, this intersection will not be subjected to more total or
differential settlement, or rotational forces than at other locations along the perimeter
corridor where the containment berm is not present. This type of berm system is utilized
at the BR Tower Landfill and at many other landfills throughout the U.S.
The thin layer of waste material located beneath the extension of the containment berm
(i.e. that portion of the containment berm placed over waste) will be compacted during
construction of the containment berm. This compactive effort combined with the relatively
thin layer of waste located beneath the extension area will minimize any potential
settlement below the extension of the containment berm. The configuration of the waste
material above the containment berm extension is the same as at other final
cover/perimeter corridor intersections at this facility and at most landfills. Therefore,
minor settlement in this area will not effect surface water control structures, the final cover
system, or any other landfill component differently than at any other intersection at the
facility.
Comment No. 2
The containment berm is proposed to be constructed with an internal clay wall that will be
supported from the outside with compacted backfill while the inside will be supported by a
combination of compacted backfill and compacted refuse. There is some concern that the
difference in densities of these materials (compacted trash and compacted backfill), along
with differential settling on either side of the clay wall, may cause the clay wall to move
during the post-closure period. Documentation must be submitted which addresses the
issue of potential settlement and movement associated with the containment berm. If
calculations show that movement and/or settlement will occur, describe how this may affect
the final cover integrity and performance of the surface water run-off structures.
Response No. 2: The "internal clay wall" is shown as a representation to indicate that this
area will be subject to the same construction quality assurance (CQA) monitoring, testing,
and reporting requirements as other compacted clay components of the liner and final
cover system. It is anticipated that the entire containment berm will be constructed of
similar soil material.
2893RSP.DOC Golder Associates 962,3€ 1
August 1996 5 953-2893.003
As shown on Detail 1, Figure 11 and Detail 1 of Figure 12 of the design drawings, it is
envisaged that the internal slope of the containment berm will be sloped at the angle of
repose for the soil material (about 1.3H:1V) in order to construct the vertical component of
the clay liner.
Settlement of the extension area, as discussed in Response 1, above, will be minimal.
Additionally, the internal clay wall of the containment berm is tied into and founded
directly on compacted clay liner material and is therefore not subject to rotational forces of
potential settlement of the extension. The perimeter corridor of the present and future
landfill cells at the facility are constructed by excavation into natural ground or by placing
structural fill. Since significant compactive effort is imparted to the structural fill by
construction equipment and the natural strength of the existing ground in excavation areas,
this area will not be subject to greater settlement then any other area of the perimeter
corridor.
Comment No. 3
Please describe in detail the phases of construction that will be necessary to build the
containment berm.
Response No.3: As waste material is placed within the landfill it will eventually reach the
top of slope along the perimeter corridor. Either before or concurrent with placement
above this elevation, Laidlaw will construct the containment berm. The entire berm will be
constructed in its entirety or in sections at the discretion of Laidlaw based on waste
receipts of other operational factors. The containment berm will be subject to the same
CQA monitoring, testing, and reporting requirements as all structural and compacted clay
components at the landfill as per the existing facility CQA plan and specifications.
CELL C DESIGN CHANGES
Comment No. 1
On page 19 of the facility's September 1991, Design and Operations Plan, it states that the
coal mine workings in the area of the landfill may create subsidence of up to 2' within the
landfill with a maximum slope change of 1.6%. It also states that this subsidence will not
damage the composite liner system which can sustain uniaxial strains of at least 10%, and
that positive drainage to the sump will not be compromised as a 4% grade has been
incorporated in the liner design.
Please explain whether or not this subsidence has the potential to "backtilt" the leachate
drainage system if the base grade is decreased from 4% to 2%, or if potential subsidence
could have any other detrimental effects on the integrity or performance of the liner and
leachate collection recovery system. In addition, submit an analysis of leachate flow travel
289112SP.DOC Golder Associates 9623€^1
August 1996 6 953-2893.003
time assuming a 2' subsidence occurs under cell C, and the design base grade of 2%, has
been decreased by an appropriate amount.
Response No. 1: The limits of the coal mines workings has previously been presented on
Figure 14 of the September 1991 permit drawings by Golder entitled "Laidlaw Waste
Systems, Inc., Denver Regional landfill (South), Weld County, Colorado," Golder Project
No. 913-2324. Also, the limit of potential subsidence has been previously shown on Plate
1 entitled "Worst Case Subsidence Prediction" of the subsidence prediction report by
Golder, dated 1991, Golder Project No. 903-2284. As shown on the subsidence prediction
plate, an area which may receive 6-inches or less of subsidence extends a very short
distance beneath the Cell C area.
As shown on Figure 3 of the February 1996 design drawings, a portion of the northern
edge of Cell C, corresponding to the limits of potential subsidence, has been designed with
a base grade of 4 percent. The mine workings are not present below the Cell C area.
Therefore, the design strains for the geomembrane will not be exceeded and flow of
leachate in this area will not be effected.
Comment No. 2
The leachate flow analysis in the sand drainage layer assumes an additional I' of head
within the sand layer. The leachate calculation should evaluate leachate that flows directly
on top of the composite liner using the base grade of the waste cell. However, it would be
appropriate to calculate leachate flow analysis using a head value as determined from
HELP runs for this facility's design.
Response No. 2: As presented in Appendix B of the design report, the longest travel time
for any of the areas within Cell C is 167 days. This is for the area located in the southwest
corner of the cell.
The travel time is a direct function of hydraulic gradient. Using Darcy's law, travel time
is expressed as:
t = 1/k*i/ne
where: t = travel time,
1 = travel length,
k = hydraulic conductivity,
i = hydraulic gradient, and
ne = effective porosity.
The gradient presented on Table 1 of Appendix A for the southwest corner is 0.023 which
is the sum of a 2% floor slope and 0.3% slope of the 1 foot of leachate assumed to be
present. If it is assumed that the leachate is not present, the gradient in this area is reduced
to 0.020. Thus, the range of hydraulic gradients ranges form 0.023 to 0.020 The
relationship between gradient and travel time is inversely linear. Therefore, a reduction in
2593RSP.DOC Golder Associates 9622c1
August 1996 7 953-2893.003
gradient is directly proportional to an increase in travel time. Thus, if the gradient is
reduced from 0.023 to 0.020 the net change in gradient is 15 percent. Using the hydraulic
gradient range of 0.023 to 0.020 the travel time ranges from 167 days to 192 days. This
range is less then the regulatory travel time of 365 days.
General Comments:
Comment No. I
Any location where a perimeter channel is located close enough to the composite liner
and/or waste to cause erosion or stability problems must be lined with rip-rap or other
appropriate armor to protect the integrity of the landfill through the post-closure period.
Based upon recent on-site observations, certain segments of the southwest perimeter
channel are experiencing excessive erosion.
Response No. 1: Appendix C of the design report provides surface water calculations for
the channels at the site. The channels have been designed for landfill closure and the 100-
year, 24-hour storm event. Table 2 of this appendix provides a summary of the permanent
channels and the lining (erosion resistant armoring) required for these channels. The
lining type is based on the flow velocity and bed slope of the channels during the closure
conditions.
Final channel lining materials will be installed prior to facility closure. During the active
life of the facility, the channels will be maintained by Laidlaw to not pose a threat to the
structural integrity of the landfill.
Comment No. 2
After reviewing the surface water channel data listed on Table 2, it appears, based on
shear stress values, that "armored" lining for channels BSA and B-1 may be more
appropriate, then the proposed grass lining. Please provide justification for the lining type
chosen for the aforementioned channels.
Response No. 2: The determination as to the need for armoring of a channel is based on a
flow velocity and bed slope as discussed in Appendix A of the design report. If the flow
velocity in a channel exceeds 8 feet per second or a bed slope is greater than 20 percent
channel armoring will be required.
As shown on Table 2 of Appendix A, the flow velocity in channel B8A is 8 feet per
second, thus not exceeding the design velocity. Additionally, as shown on Figure 1 of
Appendix A, channel B8A is located to the north of the facility and is not adjacent to waste
placement areas. Therefore, channel lining is not required in this channel.
289IPSP.DOC Golder Associates 962361
August 1996 8 953-2893.003
As shown on Figure 1 of Appendix A, channel B1 is located adjacent to the final cover
access road. As presented on Table 2 of Appendix A, the bed slope of channel B1 is 5
percent and the flow velocity in 6.7 feet per second, thus not exceeding neither the design
bed slope or flow velocity.
We hope that these responses answer questions that the CDPHE may have concerning this
facility. If you have any questions, please contact the undersigned at (303) 980-0540.
Sincerely,
GOLDER ASSOCIATES INC.
Dean Rector, PE
Senior Project Manager
qj2gra, Oja)
David L. O'Sadnick, PE
Principal
DVR/jck
Attachments: Figure 1 and 2
cc: Mr. Rick Hoffman, Laidlaw Waste Systems, Inc., Weld County, Colorado
Mr. Kevin Carel, Laidlaw Waste Systems, Inc., North Richmond Hills, Texas
2593RSP.DOC Golder Associates
962=3c1
w
2Z
xO ZA
d t 8 d
t5 o g of �a�?
\ 121
EN
F 8-1
0 Leg y a 60 2 g 1
W 30 O ' ! 6 aET FA N
< pp < Z 5 so
F
. X co r< Z CC0 N i � tq O3 NFU
a O 6 y ge 6 ca- a Fn
w
f l H
2irfry D
I a !THPP
/
; tl lI -
ii \
-cs r r_ x� .. _ -----ter-.'--_ -(T.'-727 -..a r- .- _ _......
?.
r f -_
1 /- 1
L
y ; r \ \ / / / r
N.
\\" \\\ ‘\ \ :----
I\ \) ; "Il 1 1
1 Ail > > • I
' , ' ' } •,( ' ' , 1fiI (
)', f ,,r, !i \ - ; '00 / ]'
(/( 1J
_ Q
' � ll
1 II
' i .) i I .�v,I \VAV I oil \ �W /� i
f 4
01#11
' ; i (�_) i���Oi 1 \\ 1, \ `` . iio 1 W" i I,
000! l/3 /, )i1 f- ,/ / / ie , /; 'A.-4-s 1r( j % TI %� l I/ N %% % ' , ) I
, , i1,. - )�1;? \ .\ } / , ' \ \ •` %%(10 ! r 7/ 1 1 0 I } 11
/ .I I / I1(\`k'I%' / //(I \\�, J ' %% I ! ( // K / I/
/
' �- I / i . i/ /I'
�� ( I ,r �/frit,Sri // i ( // / %
W ,
/ ` +jf, 11 0 ; `• /p I : i as ^ ( 44'' j /` /
� cc 00 ✓a-
\ } . /0'rr. rrriariirr j
,
COMPOST AREA FLOW CHART
RECEIVE AND LOG
COMPOST MATERIALS
I
SEPARATE GARDEN, GRASS CLIPPINGS
FROM OTHER COMPOST MATERIAL
SORT AND SHRED
AS NECESSARY
i
MOVE TO ACTIVE AREA
I
MIX MATERIAL AT A RATIO OF
1 PART GARDEN WASTE/GRASS TO
3 PART LEAVES/WOODY MATERIAL
i
ADD 1 PART CLEAN SOIL TO
50-100 PART COMPOST MIXTURE
I
CHECK C:N RATIO
AND pH
IS C:N RATIO NO ADD N AS NEEDED'
25-30C:1 N9
YES
IS •H 6-7.59 NO — ADD LIME AS NEEDED
YES
IS MOISTURE CONTENT
60-75 PERCENT BASED NO H ADD WATEF
ON VISUAL OBSERVATIONS?
TYES
WINDROW MIXTURE
I
MEASURE TEMPERATURE DAILY
NO IS INITIAL TEMPERATURE AFTER
1 TO 2 DAYS >131' F?
YES
TURN WINDROWS EVERY 3 DAYS
FOR 15 DAYS
AFTER 15
HAVE OBJECT ONADLOORDERCOMPOST YES
CONTINUE C01
n
3)`O J NO
3)cn '
>D I
° PLACE INTO CURING PILES IN
FINISHED PRODUCT AREA
N i
no
0 .. PA I I Kr nR RAI F I
STATE OF COLORADO
Roy Romer,Governor OF Co
Path Shwayder,Ixecutive Director rnac'tf%
Dedicated to protecting and improving the health and environment o!the people of Colorado
• - •
HAZARDOUS MATERIALS AND WASTE MANAGEMENT DIVISION •
r I8l6r
4300 Cherry Creek Dr.5. 222 S.6th Street,Room 232 _
Denver,Colorado 80222-1530 Grand Junction,Colorado 81501-2768 Colorado Department
Phone 1303)692-3300 Phone(303)248-7164 io Public Health
Fax(303)759-5355 Fax(303)24&715i8 ofand Environment
September 17, 1996
Mr. Rick Hoffman
Laidlaw Waste Systems, Inc.
1441 Weld County Road 6 V 1c1 County Planning Dept.
P.O. Box 320
Erie, Colorado 80516 SEP 2 0 1996
RE: Modifications to Design and Operations Plan e Y 1...�
Denver Regional Landfill (South) (DRLS) EC I V
Weld County
Dear Mr. Hoffman:
The Solid Waste Unit of the Hazardous Materials and Waste Management Division (the
Division) has completed its review of the April 1996 document entitled "Modifications to the
Design and Operations Plan for the Denver Regional Landfill (South) Weld County, Colorado"
and subsequent letters dated August 13, 1996 and September 9, 1996 submitted by Golder and
Associates, Inc. The proposed modifications include: 1) an addition of a 3.5 acre composting
facility, 2) relocation of the sediment basin, 3) combining Cells C and D into one cell and 4)
the construction of"a perimeter containment berm.
The Division's concerns regarding the proposed modifications were addressed in a letter dated
July 29, 1996. Golder's letter of August 13, 1996 adequately answered our concerns with
respect to items 1, 2, and 3 from above. On August 30, 1996, a meeting was held to discuss
the unresolved issues regarding the proposed containment berm. Subsequent to the meeting,
supporting engineering calculations were provided by Golder in a letter dated September 9,
1996.
We have reviewed the calculations presented by Golder. Although the results are reasonable for
the approach selected, there is still some concern the containment berm will perform as
presented in the design documents. In addition, we have received design drawings dated 1983
describing a similar (though not identical) perimeter structure used at the BR Tower Road
Landfill. While the Tower Road design included construction of perimeter soil berms over
waste, it is our opinion that there is enough difference in the two approaches that a direct
correlation between the performance of the DRLS design and the Tower Road design cannot be
made.
EXHIBIT
9%J '..w9
Mr. Rick Hoffman
September 17, 1996
Page 2
Due to the above concerns, but with consideration to Golder's conclusion that the perimeter
berm will perform as intended, we hereby approve the proposed design with the following
conditions:
1. Settlement monuments shall be included in the construction of the perimeter
berm and the adjacent final cover. The intent of the monuments will be to
monitor the relative movement of perimeter berm and the final cover.
Monuments shall be placed in pairs, one at the top of the containment wall, and
one on the barrier layer of the final cover immediately above the inside toe of
the perimeter berm. Monuments shall be placed at a spacing of 500 feet along
the length of the perimeter berm.
A plan for placement of the settlement monuments, including timing of
placement, location, design details, and proposed frequency of surveying, shall
be provided to the Division for review and approval prior to completion of the
perimeter berm for Cell B.
2. If operational and post-closure surveying of the settlement monuments indicate
that differential settlement between monument pairs results in tensile strain in
the cover barrier layer of greater than one (1) percent, further assessment and
remediation - including evaluation of the final cover barrier layer - may be
required. Determination of actual required measures will be based on overall
site conditions at the time, should this situation develop.
3. In the area of final cover between the toe of the cover and the point immediately
above the inside toe of the perimeter berm, the barrier layer of the final cover
must be constructed with a moisture content at or above optimum moisture
content as determined by Standard Proctor. This requirement is based on
information on Page 22 of "Design and Construction of RCRA/CERCLA Final
Covers" EPA/625/4-91/025, where it is stated:
"For cover systems, ductile soils that can withstand significant strain
without cracking are preferred. For this reason ... it is preferable to
compact low hydraulic conductivity soil layers wet of optimum."
The settlement profiles provided by Golder show that the maximum differential
settlement (and tensile strain) would be expected adjacent to the perimeter berm.
It is for this reason that the requirement to place cover wet of optimum is
needed in this area only.
962361
Mr. Rick Hoffman
September 17, 1996
Page 3
If you or your consultant have any further issues that you would like to discuss, please feel free
to contact us. Otherwise, this approval will allow Laidlaw to begin construction after receipt
of this letter and after any additional Weld County requirements have been met.
If you have any questions regarding this matter, please contact either of the undersigned.
Sincere
Steph Laudeman, P.E. Roger Doak
Geol ical Engineer Geologist
Solid Waste Unit Solid Waste Unit
Compliance Program Compliance Program
cc: Gloria Dunn, Weld County Planning Department
Trevor Jiricek, Weld County Health Department
Dean Rector, Golder Associates
sw/wld/las 3
9sz.3€ .
Gloria Dunn, W.C. Planning Department November 5, 1996
Trevor Jiricek, W.C. Health Department
Laidlaw Waste Systems, Inc., 2nd Amended USR-972
We have reviewed the development standards from Amended USR#972. As the result of this
amendment we recommend the following modifications and additions to those standards:
1) Wherever there is a reference to the Colorado Department of Health it should be amended
to state Colorado Department of Public Health& Environment.
2) Development Standard#1 should be amended to include the use of a composting facility
and recycling facility.
3) The third sentence of development standard#8 should be amended to state "The
analytical method and statistical evaluation of groundwater monitoring data shall comply
with the Regulations Pertaining to Solid Waste Disposal Sites and Facilities contained in
the Colorado Code of Regulations, 6 CCR 1007-2.
4) The third sentence of development standard#10 should be amended to state "The
working face will be closed to disposal when high-wind warning conditions exist as
defined in the Regulations Pertaining to Solid Waste Disposal Sites and Facilities
contained in the Colorado Code of Regulations, 6 CCR 1007-2.
5) Development standard#11 should be amended to state "In accordance with Section 3.1.1
of the Regulations Pertaining to Solid Waste Disposal Sites and Facilities this facility
shall not pose a bird hazard to aircraft. The facility must be operated in accordance with
the Final Report Bird Strike Hazard Study, dated September 1993".
6) Development standard#12 should be deleted. This standard is replaced by a more
detailed standard.
7) Development standard#25.c. should be amended to state "Liner certification reports."
In addition,the Division recommends that the following development standard be incorporated
into the current standards:
1) The Weld County Health Department, Weld County Planning Department, and Colorado
Department of Public Health& Environment shall be notified in writing of any new
materials (other than green wastes, i.e. grass clippings, shrubbery trimmings, leaves,
EXFfIB�IT
962361
garden wastes, etc.) which will be accepted for composting. Written approval to proceed
with composting shall be obtained from the Weld County Health Department and the
Colorado Department of Public Health& Environment prior to receipt of the new
material. Submittal information shall include operational procedures and storage
procedures. All materials considered for composting shall meet current and future
regulatory requirements for that specific material. No dead animals shall be composted
on site.
2) No stockpiling of raw compostable materials shall be allowed on-site. All raw,
uncomposted materials shall be placed in windrows or other processing unit within 48
hours upon receipt at the facility. This is not meant.to include bulking agents such as
wood chips, etc.
3) Records shall be maintained which include the tonnage of raw materials received at the
composting site and the tonnage of finished materials removed from the site.
4) The facility shall submit a fly control plan to the Weld County Health Department for
review and approval. The facility shall be operated in a manner to control flies. The fly
control plan shall be implemented at the request of the Weld County Health Department
in the event that flies (which can be determined to be associated with the facility) are in
such a number to be considered a nuisance condition. The plan shall also be
implemented in the event the Weld County Health Department receives a significant
number of fly (associated with the facility) complaints and in the judgement of the Health
Officer, there exists a fly condition requiring abatement.
5) The facility shall submit a odor control plan to the Weld County Health Department for
review and approval. The facility shall be operated in a manner which controls odor.
Odors detected of site shall not equal or exceed the level of fifteen-to-one dilution
threshold, as measured pursuant to Regulation 2 of the Colorado Air Pollution Control
Regulations. The odor abatement plan shall be implemented at the request of the Weld
County Health Department in the event odor levels detected off site of the facility meet or
exceed the level of fifteen-to-one dilution threshold or, in the judgement of the Weld
County Health Officer, there exists an odor condition requiring abatement.
6) The previously submitted and approved fugitive dust control plan shall apply to the
composting site and operations.
7) A metal sign shall be posted at the entrance to the composting facility. The sign shall be
a minimum of four feet in width and three feet in height. The sign shall state:
A) Name of operator.
B) Wastes accepted for composting.
C) Emergency phone numbers of the facility operator.
8) The facility shall comply with all materials submitted as the result of this Certificate of
jf 361
Designation and Use by Special Review.
9) As a form of vector control, the facility shall remove any accumulated water in the
compost perimeter channels within seven working days, weather permitting.
10) Settlement monuments shall be included in the construction of the perimeter berm and the
adjacent final cover. The intent of the monuments will be to monitor the relative
movement of perimeter berm and the final cover. Monuments shall be placed in pairs,
one at the top of the containment wall, and one on the barrier layer of the final cover
immediately above the inside toe of the perimeter berm. Monuments shall be placed at a
spacing of 500 feet along the length of the perimeter berm.
A) A plan for placement of the settlement monuments, including timing of
placement, location, design details, and proposed frequency of surveying, shall be
provided to the Solid Waste Division of the Colorado Department of Public
Health& Environment and the Weld County Health Department for review and
approval prior to completion of the perimeter berm for Cell B.
B) If operational and post-closure surveying of the settlement monuments indicate
that differential settlement between monument pairs results in tensile strain in the cover
barrier layer of greater than one (1) percent, further assessment and remediation -
including evaluation of the final cover barrier layer - may be required. Determination of
actual required measures will be based on overall site conditions at the time, should this
situation develop.
11) In the area of final cover between the toe of the cover and the point immediately above he
inside toe of the perimeter berm, the barrier layer of the final,cover must be constructed
with a moisture content at or above optimum moisture content as determined by Standard
Proctor. This requirement is based upon information found in the "Design and
Construction of RCRA/CERCLA Final Covers" EPA/625/4-91/025.
If you have any questions, please call me at extension 2232.
tj\456
JVIJ3r1
va
TOWN OF ERIE
b
/� v 645 HOLBROOK P.O.BOX 100
,1 ERIE,COLORADO 80516
Ile LOCAL(303)828-3843
' METRO(303)665-3555
_1g 74-_`"
June 13, 1996
Weld County Planning Dept.
Gloria Dunn JUN 1 7 1996
Current Planner
Department of Planning Services ,es ��+
+
1400 N. 17th Ave. r '
ED
Greeley,CO 80631
RE: Case#2nd Amended USR-972
Dear Gloria:
I apologize for the delay in responding to your referral. The following are my concerns regarding the Laidlaw
proposal.
I. The location of the composting site places it in relative proximity to the proposed Coal Creek
Heights development,approximately 1,100 feet. This could cause complaints from residents when
the wind is in the east or southeast.A site to the east would place it further away from areas
scheduled for residential development. Coal Creek Heights is in the process of annexing the east'/2
of the east 'h of Section 19 to the town.
2. The site for the sedimentation basin is within 600 feet of the proposed Coal Creek Heights
development. Again,because of its closeness to future residential property,I am concerned with
odors,and safety of children in the area. They are carefully keeping the dam to less then 10 feet to
the spillway to avoid it becoming a jurisdictional dam. There is still the potential for contamination
from leachate if the dam overtops the spillway or the dam fails. In the event of a dam failure the
water will flow directly to Coal Creek through a potentially developable area.
3. There are no details on the construction of the sedimentation dam,nor indication of a clay core for
the dam or a clay liner for the sedimentation basin. I presume that the present sedimentation basin is
clay lined for percolation control. Monitoring wells should be provided up and down stream of the
sedimentation basin.
4. It should be noted that the site is within the Erie Airpark Influence Zone.
EXHIBIT
.3623f.A.
POLICE DEPT. P.O.BOX 510 METRO(303)449-3156 LOCAL(303)828-3200 LONGMONT FIRE PROTECTION DISTRICT (303)666-4404
Gloria Dunn
Page 2
June 13, 1996
5. I see nothing that indicates a landfill gas(LFG)mitigation system. I don't know what the state
requirements are for LFG mitigation. I am concerned because of the uphill location allows the LFG
to flow downhill off-site and possibly collect in depressions in residential areas,posing a hazard to
the residents.
I trust that these comments will be of assistance in your review of the proposal.I have also enclosed a copy
of an interesting article on landfill gas from a recent American City and County(May 1996). It is though
provoking.
Sincerely, /7
Gary
Co ifity Development Director
Enclosure
cc: Barbara Kirkmeyer
COVER
S T O R Y
Vigilance and sound
ad vice help s ell reli ef
p
from landfill gas
ti
_ . .. ..
-
,. - 4Y w ..
.. tea[.„,_,.....,,_
.6 . •. si„,...•s,..„.„
.....,_
. , „.. .. .......„- ••: .
.xE,,,• :
. ...„ ...,
s.: T ±J7
e }. .
= .
Whether immediate problems, emissions regulations or a desire to
plan ahead are the motivation for installing a landfill gas system,
clearly defining the system's goals is a crucial first step to success.
occer matches at the Renaissance Park unique challenge. The soccer fields were built
S
athletic complex in Charlotte, N C., atop a 375-acre landfill that was operated
bs
are often fast-paced and exciting the art from 1965 to 1956, and the Renats-
Action at the golf course across the street is Rance Golf Course cluohouse sits ahour 100
much slower. but still has its adrenaline- feet from the landfill's perimeter..
charged moment. To call either sport exploit The threat of explosion is a result of the
sine, however, is a stretch, and local officials landfill gas (LFG1 generated be 11.3 years
are trying to keep it that wac. worth or decomposing solid waste buried at
1t 6tno pupa', ,..cation that presents this the site. A hint or the potential dangers came
By Rob Shapard
Assistant Editor e r" -1
.
22 Vlax I996 AMERIc.AN CITs & COI_yT•
--
in1995. when a quick flash ;Et gas nearing and Pruper[y management for example, are roing to he higher."
burned a woman at the soccer fields_ department. 11X everthele s, a passive Other steps taken at Ren Iusance
The gas had accumulated in a small system allowing LPG to vent away Park to deai with js,Rdi. ..nth ne[,Iry
depression and ignited at[er the rem the building was installed .as a and tenter the problems in 1905.
woman lit a cigarette near The spor precaution_ include:
Settlement of waste was the culprit, However, [he cine111.a: c Se,- • a telling around 30 permanent-
according to Tom yIcDermc.rt ,ai the rem proving to he insufficient, monitoring wells along the landfill's
\lecklenhurg Coun[v Park and Recce- according to Carpenter, as tests are nenmcrer, [o _rack potential mum-
anon Department, which leases the slit-tenth v showing 40 percent to dd non of LEG from the situ,
complex from Charlotte Serdement percent concentrations of methane • closing off areas in which e:Is
caused the depression to rosin next to around the foundation of the club- could accumulate_ Storm drains. for
a concrete lighting pad. and LFG house. Therefore, an active system, example, have been covered with '
migrated along support pilings into consisting basically of a vacuum pump grates; and
the eroded area. to flush out any LPG and draw fresh • hiring a consultant to conduct an `
The fir[ step Of park managers was air through the foundation, will he overall sire assessment. At the consul-
to pump a slurrm- c material installed ror around 56f_J00 tan['s recommendation. the up has
beneath the pad and to improve Overall, in the past year the cin instituted a monthly monitoring pro-
response time in filling any other has spent around S400.000 on [he first gram that targets possible gasouilau:
eroded areas_ "One of .he things [hat major re-working of the site, Careen- and migration_ The prcwrarn irciddr,
we have to watch much more closely ter says. A private consultant recently site ;nspealons for any eroded areas
is settlement,- McDermott says, "and estimated.fu[ure maintenance costs at where gas could accumulate and a
we have to rake care of [settled areas] the park will be 5».000 a gear and written record of the department's
immediately." 5:50.000 every five years or so for efforts.
LPG also showed up last year at the major re-grading- These costs include "The landfill seems like it's always
golf clubhouse, which was closed after dealing with LFG as well as other changing," Carpenter says. "Some-
gas sensors installed in the building issues related to the park's location. times there is gas, sometimes there
detected unsafe levels of methane. "The fact that methane gas exists at isn't. IT can change day to day. yea: ro
The city had first tested for LEG these facilities should not be a deter- year.
when the clubhouse was built and rent for others considering building "The [most important] thing is hay- i
found no significant quantities. facilities on landfills, hut they need to no everyone that has anythingro do
according to Keith Carpenter, a pro- go in with their eves open," McDer- with the sire daily be aware of any i
iecr manager with Charlottes engi- mot[ says. "The maintenance costs, problems that might come up and
what they need to report."
COVER STORY COMMON SYSTEM ELEMENTS
Quarry 'site to become' Landfill Lnlike the passive venting ,ri>inal-
ly installed at the Renaissance club-
house many systems actively collect
After years of effort, Bristol, prohibitive costs inhaving to build LEG and may incorporate several of
Va., receiveda9ermit in Feb pad operatea landfill-to serve only the following elements:
ruary to convert arc^abandoned .- ;t9 a • probe to monitor any gasmwrar-
w n ,„
quaryinto aregional landfill.This. '
,th"t-h`e"hope of creating a tng Hare ahe la-bifill site, The mos:
new facility is expected to be_a rev- large, regional,facility:that could importanr characteristics of t r0 to
enue-generating,-profitable-venture .serve a wider geographic region monitor are temperature. thaw rate,
'Waa.cr
andwill be able to service afive or"�-" �aGG exaeraae�ez•eaue the city compos[ion and pressure,
six-countyiegeon B. 3d .,p ,tee quarry Pro • vertical gas extraction wells, well-
� �� n,.,.
e sw f rants Deer- heads and header pipes that collect
.� � .$ quarry `
-)�` j 47 :,' ..r fazge`pre ,W `ii ,I '. ' gas from throughout the landfill:
to a`al-^ .� . ". . e•- • a flower that vacuums LFG
rate We •¢ail u rxb4d`• call ialletia g to through the pipe system toward a yen-
tosete�.ie
Lilo' •"-k-„ triinisml - ' 7. a,,, ,s 'rail is •.w - tral point.
.nes'�J istat +� - i * ..pr , .,,0r e4f& �, '▪ -' • a rank rot storms] condensate char
a = -ewy 1 --: _` ▪ forms as LPG cools off while moving
-spacer e L Iy'S ma znze 2a -S .-,�.
riiia otata�r tie 172; i r,": ^` s x, through me system-
not-enough,t• rlge.`ro I "° Pt-''i 'rt E•"-°'r-+r "'n": •an enclosed flare system or utilttt
est from private industry an. at 'l onxu its,. v i a� flare skid to burn off LPG: andior
the city would end up payinglugh- of:400 epd'of waste#oi40 years.,. • a gas-to-energy facilite. ,
er disposal:rates to transport trash 'Opetat�ns_:are expected to begin Assistance from experienced team ,
o ti
to afaz-awa 'xite � .. �.. ��q .Bristol also faced` =in'theseecii`d�eiarter'o�-1997_ _-T7-" members with up-to-date knowledge
, 9& tectilly and regulations is vital
24 Slay 199b
AMFRica CIT1 & COUSp1 . '`v,
LANDFILL EMISSIONS REGS in chcuulnc in appropriate system.
This mac ins ois e using city or counts'
The Emissions Guidelines and methane organic compounds. cne!VI eco. private cnunecrs or [-orb
New Source Performance Standards Sites meeting both conditions ssiiri,inu bigot—car.
-published by EPA this March have have only a few months to install Long-term planning is also vital.
operators scrambling to learn if their active collection systems to be in since rattails or c.arrierclh- cl,sed
sites are-affected. The new rules compliance with EPA's regulations. ,itc< mac gene-arc LFG for -es eral
have two basic conditions: The Solid Waste Association of decides Gang rr.>m hoc-c„a, I , high-
• Landfills must have accepted North America is conducting edu- cost soiurions mac he coot- axnensice
waste after Nov. 8, 1987, and have a cational seminars on the regulations ill the ion, run it initial srcoo prose to
design capactty,greater than 2.5 Mg; in Washington, D.C., Los Angeles be rncfrectice-
•tln.addidon la idfdls'inusremit and Chicago,;and can be reached.at
morethan`50 Mg-per-year of non (301) 585-2898 {r DEFINING GOALS IS KEY
Whether immediate problems. reg-
ulations or a desire to plan ahead are
- - _ diving landfill operators to deal a nth-. - �'�- k � -- LFG crucial nrst step I t icrcr-
.a. - ,hrs,.,c, '. ^=�'a�'"-ti mine a systems goals. Some n cmcors
ma} simply need to limit odors:others
r — -- mac he seeking to control mieranon
„ ��,, �,' '.. or air emissions or to generate >as_ro-
" energh revenues.
-'
i At sites where odor control is the
—a
. - primary goal. some sort or p a sire ss-
•
..o.qa •:�,y 3g • .. �� t, rem allowing ea n vent i eroharlc
.. 4 r -_1 " already in place according. rc Alike
- r _ Micheu, a senior environmental enet-
i.
•.-- 'i nee- in Camp Dresser S.. A1ckee a
Milwaukee orrice As the system venom
-�,.._ r'• gas. the smell provokes complaints
M 1.'
•
�,- r ��� -yt from nearby residents or businesses
-Er lip e• . _ e A simple and relatively inexpensive
--r f Hs 1. - 6 t option is TO install odor-absorbing rtl-
•' % tern on the vents. "Sometimes filter
work and [operators] save themselves
a lot of money." Michel saes.
However. this option can he fairly
labor-intensive, since the filters must
' be replaced once their carbon content
Engineering solid solutions. a depleted. Connecting vents with an [
aboa eaground pipe network and 1
To stay ahead of your eaerchanging challenges in solid waste
:umr
;management you need a partner who understands out needs and !LOU o �. a a n ace-
, v-gallon carbon canistermay re
the environmental requirements you face. The leading landfill - _
designer in the L'.S.. Rust Environment 8 Infrastructure uses its CI
more effective.according to Micneis
The canister acts like a larger ver-
experience and leading-edge technology to engineer practical sion or the vent filters, absorbing
emiromnentalb sound solutions.
odors through one use of carbon. The
I Our engineers and scientists can take your project from start to L barrel is either replaced or regenerated fh
finish with our full range of integrated services. including once the carbon is spent.
permitting. design and construction quaiit>. assurance for landfills. Pumping LFG to a central flare is a -
MRFs. and landfill gas-to-energy. leachate management and air third option for controlling odors lni-
qualir control systems. To assemble the right team of experts.call nails more cosdi than filters or cot- Gn
I-80o-868-0_U. lection barrels, an active flare system
in the long term may he a more cost-
effective solution. OD
RUSTOperators dealing with an LFG Fe
migration problem have both passive -
Rust Environment & Infrastructure and active options as well. Digging a
I cur-off trench along the landfill 1
boundary through which LFC is
Greco A .- s React ,ue:.arc ���
26 tlac I096 ERICA] Crn S: COL NTT
migrating is a common relatively sim- cur off trench are a concern, since hackt i! the trench or adding a
ie passv"c solution. LFG can continue its migration along geomembratie harper r mac make the /�
since LEG seeks the path of least these trenches toward mhahired areas. trench more effective. once these �"'[
resistance as it moves underground, Geology and water table location materials are more likety to torce
the idea is to provide a new path. A are also important factors when con- migrating gas upward in sandy soil to i1
trench 'oackfilled with stone can inter- sidering a cut-off trench. according to vent to the surface
cept LEG and allow it t. :ravel ylichen. In an area with sandy soil, The depth of groundwater la also
upward and Yen; onsire. •efore it tor example, the difference between crucial to consider, since gas typically
-hreatens any srructures located near -he trench and surrounding soil may travels anywhere between this depth
me landfill. not be great enough to ensure that gas and the ground surface. An effective
The cur-off trench should run far will travel upward to vent once it cur-off trench should tnerefore he as
enough so that am gas escaping reaches the trench. deep as the groundwater to ensure
hound its ends w,I. not reach such In this situation, using hentonite or that all potential migration > con-
structures. utility trenches near the clay rather than washed stone to trolled. In areas with a deep water
I
1
COVER STORY
Public/ riate arthershi helps rehash trash
In September 1 95 .. e unified unmanned drop-off centers,a.curb- fee is set on a sliding scale;so that
government o Athens Clarke side collection program and coin- the feedecreases as tonnage increas-
':' ttlC 4 eaiem axnew merctal'bus ness collection. es. ACC-rec.ives.80 percent'ofthe
tbettma. Years+ f The RMPF,can process up to 120 revenues generated Throngh'd-e sale
�ch t Brings and is designed to accept recy- of recyclable materials
lea- 'e#fhe yvr efiislaneataaf a tomes m two Clean commingled In the seven months since the
s
prehervxve waste management plan streams„,.-,.. a paper stream.and a program began recyclable tonnage
used fee �eonrarnerram The paper stream has increased dramatically. Immedi-
' , ,,4., atelyfollowrn far lementa-
,.,.for, Sad_a �,� , . „��„v; -�.Q• .., �<'tilc�so�;a ' .t • ...t S P
TO- - „zion of the program, tonnage
any grew from seven tpd to eight I
import ycompleted con- ____ tpd, to 14 tpd In November '
struction.dfats Recovered ij 'tiu „;.-- 1995 and 18 cpd.in: anuary
2wiateaial mcess , acilir t { ii :1996. The most current aver-
_ g Y' II 11/l11IlJ' 01 �� _ age is 23tpd oft clables
JRMPF)" re`ffrse of its kind' - fl gec9
in the state. _, The SWD is awaiting
' "The program is very corn- - .j, . _ approval of a program that '
prehensivr;'lays'`Paula'Lon>`"' ` "� - would' encourage commercial
go, rhe'recycling;coordinator r J businesses to increase their
. it v;
tfor,rhe-Georvia'Depamnenr _r -participationrnihepiogram
oLjComtn - -T rs •_a - _. Residents.hne,had S:
f "'• "di!5s'a"f iverinaCeni''23'16134 ` •_ .k .Via �Y.
tha *s going toy �. � years of enucation'and wet
lent and - •efff for. reeydablesaothis:Recovered Matenalfrocessing Facility ready to participate, "says
' ••.. „ ina partner panmtha,privatevecyciing company
thewhol tin - Sharyn Dickerson, acting
a
f. "ir` Ad • , n gated azd „ aecoroF the SSDiTwev e,the
ate. at u ' y, s .. zr. t., . , ' s tux. . 'S. e
• t ' ; '= qQ c •• maga,;Feaier' 3PPortumrourcrs °ecy
.•
tii k4. zj•t .cf' . ' o. ail clable tonnage tests with • met„.
C t 1 L -rS^ cli l 3 it: .f, e• La. • neSSeS'''
'III 'n v
� r Q. 9 Q '� t 1tikf,I.L ,r aStics I t f r�,'Li • k i l l
.Res E "•"Mf.+a-„,., ,f,�i" ,_" t� a .�-- ,` ha -t Lr Y Cw, a ✓ ec
•'9:i'•4 V r 117 ay Y ! , s.'w 1#QI.&Q rj.r. +-• 're.e�eh-ea f Cy t hat nimoeew,fivitre'v
eTi.
eaued
' b,Zr.w .. ..�:. .r .,,r:,z._ "::,,IN ±ItItrrwcz
-.hesorte8zettxlessu - 4
t00,&i toreceimmsePeatoa um= -
uQ 4 ,. , • a _fi_. • t • }ace ,' uotfalutoxmatn�t. $.'
-w Y.<. ^'a -�r' ,1tMeo M1�, • • : ,.'..°€p._.- 07°e..rn :t tompany - 'a r _
onne
r- - t'.:._ei, . A e. •r 'Y"" - ^'"'"" tsy�iatenals r 'T7iis,nmcTewiasswimrten4ay„ alma
•
ACC is imder-ctract to.daliver rbcessed at-the RMPF — $45 per Tweedell, program educatiaaspeaalist
cozhe,facili 3pdhofitecy commingled paper and $86 with the ACC Salid Waste Depart-
.,: r",. . . ..
�c"1ab`les, r;w o5m six ^" a�tm foiconcamers. The zipping- ment'srecyclingdivuwn'
oc
28 May i996 AMERICAS CITY & COUNTY
table, construction of a cut-off trench nears or beneficial-use systems he connect i o the co_
may not be sst-ettectivc. Dec. 3i. 1096 to Qualify. Is.^ .rrr.r. d.i❑ce ' s . roles
In many cases, even a trench that "The trend [toward beneficial use] was sold to the Los Aneelc Depart- c
works well in capturing and venting ..mow menr of Water and Power to neip oft-
LFG may not he satisractorv. "[The :-. t set costs. In 1095, the fuel cell was - 3 -
trench] has its .Ippliultions, but it _ - . r _ disassembled and shipped ro a landfill
doesn r work everywhere, all the •n ler in Groom. Conn.. for another one-
❑me ylichels says. 'p - scar dcnnnsrr anon projce -uncles'led by =--::
Yv�? ins coror �w'ned Norrhea>r rihties. r
Such passive venting of LEG may ' is, . �:
not'De enough for some landfill opera- �<.°'��r w..! Berlin. Conn.
tors because, although the gas is con- a- ';.- _ The experiments have shown fuel
tamed within the site, the danger of -� - -; _ r cells potential advantages to he low a
ors explosion remains. Sparks generated r'`.r1tr d"' emissions noise and vibration. Also. a
-t 200-kilowatt cell isca able of roduc-
on the ground could set on' such :m 'r�' yC�`e`, -� ?§ P p
explosion. - ___ /,T4.0 ing around 760,000 BTU per hour of C
One option ;s to install ::pest - - ,,. - _-'a' clean the-mai energy that could tic • ' e '
extending several feet off me around used ici 'neat buildings, according to
Active collection systems commonly use ' `a
In the crencn, so that gas is s gated Ran Spiegel, EPA's project manager W
high-density polyethylene pipe to carry
j;
away from ant posslbe catalysts. A> LFG to an extraction blower and on to a rot toe fuel cell [esting. '
with odor control, a more complete flare or gas-to-energy facility. Spiegel saws operators have shown
solution to migration would be an significant interest in fuel cells, hut
active collection system that flares gas is 'poking very optimistic, very gooc steep inntial costs are a major stum-
or puts it to use. right now," he says. "[The tax credit bung block.
Michels estimates there are current- situation] has really stirred a lot cf "Technically, we've demonstrated -
iv around 126 projects at L.S. landfills work in 1996." that we can do ." he sari Economi- ,-," ,-,-
and many more overseas actively col- call}, there are a little more shades of a�`'
iect ing LEG for some beneficial use.
TECHNOLOGY ON THE HORIZON eras there
About 70 percent of the U.S. pro- Batten-like fuel cell- now in devel Fuel cell costs are currently around -
jeco involve burning gas in engines to opulent may eventually provide 53,000 per kilowatt, according co l . i_
generate electricity. Converting gas to another beneficial-use option. These Spiegel, so a ,101-kilowatt cell like the
vehicle fuel or burning it to heat boil- phosphoric acid cells use methane co one tested at Penrose would run
ers in nearby facilities are the other produce electricity and heat. around 5600.000. At that level. tor
most common uses. The technoiogv was tested success- fuel cells to be as cost-effective as
Michels expects the number of ben- fully at Penrose Landfill, Sun Valley_ flares, Spiegel estimates the electricity
ericial-use projects being considered Calif.. in a demonstration project con- generated would need to sell for
and undertaken to increase over the ducted by International Fuel Cells. around 7 cents per i,Wh.
next several months because of EPA's South Windsor. Conn., and EPA. This number would drop CO about 4 -
recently published regulations. corn- ln :993. the company installed a cents per kWh if advances bring cell
'bind with the possible expiration of Gas Pretreatment Unit IGPU at the costs down co 51,300 per kilowatt in
federal tax credits for such projects it existing Penrose gas-to-energy facility the next few year, according to
proposed legislation extending the to study the CPU's ability to clean Spiegel. At that point, the economics t
credits does not pass• operators will contaminants from LEG Attu =tic- of fuel cells may be more appealing to : -
need to install the collection compo- cessrui resting, a 200-kiiow att cell seas landfill operators. -- $ -
Do your spreadsheets have more
columns than the Parthenon? }
. #0. ..„-- ' 1` itt r<<nt & Irit • nt-At?c r� ysten '
:..„ reca's i s '.. nd A. ti a r g & in .,,,•portion-,° :
•S- .'a ewi c endllii oral., STMF
r_ ti x
i,ime- i } N n to y'•.- --= ds6 -on I - sl.Ina .'.E tment ` < u.°ninona •`•. .•ment to customer
f_raft •oj a ter onto ] ' •reads _ •Gard: a eomdlu v e-ef the-aft.;: • r•i.• and more than
'gou how m=e_mita' .c ter it id ,i: •tie of i. a -!'r ed-probf .t- = oofiexperi •. de nsethe;rf :•eider of im•estm
acts. We t-''eepyq.'' date an .• of-th- a= •ugh WI :ementt a _i s
I , Call , 'day for t tii° .
,. . n info r � ts !
$V � A �) (800) �' 66 ` TUS4TG #410/412 ; r
Circle tip.71 on Reader Service Card ^�� . w-r
30 May 1996 b `s'� ea xa icTs. CITY & Cocy
Golder Associates Inc.
200 Union Boulevard,Suite 500
Lakewood,CO USA 80228 OGolder
Associates
- - Telephone(303)980-0540 ssn
Fax(303)985-2080
July 1, 1996 Our Ref.: 953-2893
Dunn W Weld County Planning Dept.
Weldld County Department of Planning Services
1400 N. 17th Ave.
Greeley, Colorado 80631 JUL 0 2 1996
RE: RESPONSE TO COMMENTS RECEIVED
Dear Ms. Dunn:
On behalf of Laidlaw Waste Systems (Colorado), Inc., Golder Associates Inc. (Golder) is
pleased to provide the following response to comments prepared on June 13, 1996 by Mr.
Gary West of the Town of Erie regarding proposed modifications to the Design and
Operations plan for the Denver Regional Landfill (South). The following presents the
comment (in italics) followed by our response.
Comment 1 The location of the composting site places it in relative proximity to
the proposed Coal Creek Heights development, approximately
1,100 feet. This could cause complaints from residents when the
wind is in the east or southeast. A site to the east would place it
further away from areas scheduled for residential development.
Coal Creek Heights is in the process of annexing the east 1/2 of the
east 1/2 of Section 19 to the town.
RESPONSE: Laidlaw will operate the composting facility at the above-referenced site in a
state of the art manner that, based on experience at similar Laidlaw composting facilities
throughout the U.S., will not generate significant odors. As described in the modified
Operations and Maintenance (O&M) Plan, the composting facility will accept landscape
waste consisting of leaves, grass clippings, prunings, and garden wastes. Typically, the
grass clippings and garden wastes have the greatest potential to generate odors. To
minimize odor development, incoming wastes will be carefully mixed to assure that a
proper ratio of 2 to 3 parts leaves/prunings and other carbonaceous material to one part of
grass clippings/garden wastes (high nitrogen containing material). A stockpile of shredded
or chipped wood will also be kept on-site for use as amendment material, if necessary, in
order to maintain the optimum carbon:nitrogen ratio at time when grass clippings comprise
a significant proportion of incoming landscape waste. Complete details of the compost
operations can be found in Section 3 of the Modifications to the O&M Plan.
EXHIBfT
16;
9623E4
OFFICES IN AUSTRALIA,CANADA GERMANY.HUNGARY,ITALY,SWEDEN,UNITED KINGDOM,UNITED STATES
July 1, 1996 -2- 953-2893
Another key element is to properly turn the entire depth of the compost rows on a regular
basis to prevent anaerobic conditions from developing. The compost windrows will be
regularly monitored in accordance with the O&M plan for temperature, pH, physical
appearance, and odor to assist in determining when to turn the compost material. Turning
will be performed at favorable times when the wind is blowing away from nearby
residences.
The site will be maintained in a clean, well organized manner. Surface water drainage will
be carefully controlled. The composting facility has been designed to avoid direct
discharge to surface water channels. Windrow areas will be aligned to allow drainage
longitudinally between windrows and prevent saturation of the base of the compost
material. Runoff from the windrow area will be collected by the perimeter drainage
channel.
All of these design and operational features of the composting facility will significantly
reduce the likelihood that the facility will generate significant odors that could potentially
impact the proposed nearby Coal Creek Heights development when, during the infrequent
occasions, the wind is from the east.
Comment 2 The site for the sedimentation basin is within 600 feet of the
proposed Coal Creek Heights development. Again, because of its
closeness to future residential property, I am concerned with odors,
and safety of children in the area. They are carefully keeping the
dam to less than 10 feet to the spillway to avoid it becoming a
jurisdictional dam. There is still the potential for contamination
from leachate if the dam overtops the spillway or the dam fails. In
the event of a dam failure the water will flow directly to Coal Creek
through a potentially developable area.
RESPONSE: The sediment basin, and the associated final cover terraces, downslope
channels and perimeter channels, comprise the surface water management system at the
facility. All water that flows into the sediment basin will be clean runoff from
precipitation events that will not come in contact with landfill waste. The purpose of the
sedimentation basin is to attenuate runoff flows and to drop out sediment from the water
prior to using on-site or discharging offsite. No leachate (water that comes in contact with
landfill wastes) will be discharged into the sedimentation pond. Therefore, no odors will
be developed from the sedimentation pond. Also, there is no potential of contamination if
overflow through the spillway occurs.
Regarding the safety of children in the area, the entire landfill facility is presently secured
within a fenced area. During construction, the security fencing will be expanded to
incorporate the sedimentation basin and adjacent composting facility.
Golder Associates
2361
.\gcs\wV\golder\2893\!Slaw.doc
July 1, 1996 -3- 953-2893
Comment 3 There are no details on the construction of the sedimentation dam,
nor indication of a clay core for the dam or a clay liner for the
sedimentation basin. I presume that the present sedimentation
basin is clay lined for percolation control. Monitoring wells
should be provided up and down stream of the sedimentation basin.
RESPONSE: The sedimentation dam will be a homogenous structure conservatively
constructed with 3H:1V upstream and downstream slopes and consisting entirely of low
permeability silty clay material that will be excavated from the impoundment area, the
spillway excavation, and other on-site borrow areas if needed. Since the impoundment
area will contain only clean surface water runoff from the facility, a clay liner in not
necessary. The existing sedimentation pond also does not contain a clay liner for the same
reasons. Monitoring wells are not needed up and down gradient of the sedimentation basin
since the water will be clean surface water runoff. Laidlaw will monitor discharge of
water from the sediment basin as per the facility stormwater management plan.
Comment 4 It should be noted that the site is within Erie Airpark Influence
Zone.
RESPONSE: We are not aware of the definition or significance of the "Erie Airpark
Influence Zone". The compost facility and sedimentation basin, as well as the landfill
boundaries, lie well outside the 5,000 feet minimum buffer zone from the end of the
nearest runway as required by the USEPA and Colorado solid waste regulations. The
facility modifications also fall well below the FAA Part 77 regulated airspace surface.
Therefore, the proposed modifications to the O&M Plan will not alter the present
regulatory status of the landfill facility in regards to potential impacts to the Erie Airpark.
Comment 5 I see nothing that indicates a landfill gas (LFG) mitigation system.
I don't know what the state requirements are for LFG mitigation. I
am concerned because of the uphill location allows the LFG to flow
downhill off-site and possibly collect in depressions in residential
areas, posing a hazard to the residents.
RESPONSE: The landfill has been designed with an active/passive gas management
system which will collect and remove methane gas generated by the landfill. The system
consists of multiple vertical wells and horizontal trenches connected by header pipes. A
vacuum will be applied to the gas collection system if necessary to convey the gas to a
flare or alternate collection point. Gas collected from the landfill may be used as a heating
or fuel source, or may be flared to the atmosphere if achievable by a totally enclosed flare.
Installation of the gas system takes place in phases as portions of the landfill are
completed. Details of the gas management system are presented in the May 1991 Design
and Operations Plan for the facility.
Golder Associates 9623Ca1
19gcs\wp\golder\2893\la ldlaw doe
July 1, 1996 -4- 953-2893
We have reviewed the article referenced in the June 13 letter from Mr. Dunn from the
May 1996 edition of the American City and County Magazine. The Laidlaw landfill
facility, local climate, and surrounding area are vastly different from the old landfill site in
Charlotte, North Carolina described in the article where explosive LFG emissions caused
problems. No comparisons between the two sites can be made. The Laidlaw site is a
modern sanitary landfill facility where LFG generation is being controlled and managed in
a state of the art manner. The LFG control alternatives described and recommended in the
article are being installed and utilized at the Laidlaw site.
Regarding the concern that LFG from the Laidlaw site could possibly flow downhill and
collect in depressions in residential areas, please note that the site in North Carolina was
located directed above an old landfill site with no LFG collection system. Also, the
quantity and quality of LFG generation in a relatively dry climate like Colorado is
significantly less than in wetter eastern climates. For instance, Colorado LFG typically
contains a lower BTU content that makes flaring very difficult. Therefore, the flaring and
venting of the collected LFG at the Laidlaw facility has no potential to impact surrounding
low lying areas because dispersion will naturally take place once the LFG enters into the
atmosphere, preventing explosive concentrations of gas from ever being generated beyond
the landfill boundaries.
We trust that this letter sufficiently addresses the concerns of Mr. West from the Town of
Erie. If you have any questions concerning these responses, please do not hesitate to
contact the undersigned at 980-0540 or Rick Hoffman with Laidlaw at 673-9431.
Sincerely,
GOLDER ASSOCIATES INC.
avid L. O'Sadnick, P.E.
Principal
DLO/111
cc: Kevin Carel - Laidlaw
Golder Associates 98 333
C6cs\wp\doleer\2893Vnidluw.doc
mEmORAnDUm
Gloria Dunn, Current Planner May 21, 1996
To Date
COLORADO Don Carroll, Project Coordinator
From
Subject: USR-972, Laidlaw Waste Systems (Colorado)
I have the following comments after reviewing the plans and drawing submitted to request
additional composing and recycling facility.
Access:
The applicant has indicated that there will be no change to the access point on WCR 5.
Haul Routes:
The same haul routes specified in the original USR-972 will be utilized.
A solid waste disposal fund has been in place for all of the landfills within Weld County. This
money set aside will be used for maintenance and reconstruction of said haul routes that serve the
landfills within Weld County.
Internal Roads:
With regards to the internal road system, the access road will be a gravel roadway. The gravel
roadway will be maintained to provide all-weather access, and additional gravel will be placed as
needed.
cc: Commission Hall
File USR-972
:plans
cowry Qa'��`n9�e •
\
we\d
MAC " \gg6
eic)
ft GeV
EXHIBIT
I
COLORADO GEOLOGICAL SURVEY Weld CSTATE Planning�F COLORADO
Division of Minerals and Geology
Department ofr t Resources JUN 0 7 1996 � � �
1313 Shermann Street,
et,, Roomm71715
Denver,Colorado 80203
FAX (303)3)8 866-2461 WED DEPARTMENT OF
FAX(303)866-2461 '1'
NATURAL
RESOURCES
June 5, 1996 WE-96-0013 Roy Romer
Governor
lames S.Lochhcad
Ms. Gloria Dunn Executive Director
Department of Planning Services Michael B.Long
Division Director
Weld County Administrative Offices irki Cowart
1400 N. 17th Ave. vale Geologist
Greeley, CO 80631 and Director
RE: Laidlaw Waste Systems amendments to Denver Regional Landfill (South)
Dear Ms. Dunn:
We have reviewed the materials submitted in support of the above amendment request as
well as the general and engineering geology of the site and our previous file.
We have no particular problems related to the physical modifications proposed and there
are no new geology-related issues associated with the amendment.
We would offer one proposed change to the interim and final closure plans for the
incompletely composted material. When disposed of in the landfill cell, it should be placed
in a thin lift (+/- 6') over a large area to avoid future problems such as potential
subsidence due to time-wise consolidation with possible adverse impacts on final cover
topography and/or integrity.
Given this one condition, we have no objection to the approval of this amendment.
Yours very truly,
/ /7 V
Jeffrey L. ynes
Senior Engineering Geologist
JH:B:\br
wo
a 6 `
STATE OF COLORADO
OFFICE OF THE STATE ENGINEER a pe
o t'
Division of Water Resources
Fe
Department of Natural Resources
1313 Sherman Street,Room 818 \.te1s+*
Denver,Colorado 80203
Phone(303)866-3581
FAX(303)866-3589 Roy Romer
June 7, 1996 Governor
lames S.Lochhead
Executive Director
He Executive
Ms. Gloria Dunn, Current Planner
Weld County Planning Department Hate alD.
Simpson
Di
Engineer
915 10th Street
Greeley, CO 80631
RE: USR-972, Laidlaw Waste Systems, Inc.
Site Specific Development Plan
Dear Ms. Dunn:
Pursuant to the State Engineer's August 7, 1995 memorandum to county planning
directors, this office is no longer providing comments on land use actions that do not involve
a subdivision as defined in Section 30-28-101(10)(a), C.R.S. This referral is a site specific
development plan and does not appear to qualify as a "subdivision." Returned herewith are
the materials submitted to this office in the above referenced matter.
If you have any questions in this matter, please contact John Schurer of this office.
Sincerely,
Purushottam Dass
Supervising Professional Engineer
PD/JS
Enclosures Weld County Planning Dept.
cc: Richard Stenzel, Division Engineer
JUN 1 3 1996
laidlaw
RECEIVED
r
Hello