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Ungerank, Ralph
Goshien, Michelle;
FW: NABORS Leachate holding Ponds
Wednesday, October 27, 2010 1:42:28 PM
Leachate pond calculations rev 2 10-27-2010.pdf
Hey,
Can you put this on the web? permit # 5089-w
This is a updated Waste Management Plan.
Thanks
-----Original Message----From: shawki [mailto:shawki@northstarengineering.net]
Sent: Wednesday, October 27, 2010 1:00 PM
To: Ungerank, Ralph
Cc: 'Jason Kincade'
Subject: NABORS Leachate holding Ponds
Dear Colby:
I revised section 2.02 by adding discussion on the leachate delivery system into
the ponds. Please let me know if you have any questions or need additional
information.
Thanks,
Shawki
Northstar Engineering Consultants, Inc.
NABORS Landfill, Baxter County, Arkansas
ADEQ – Solid Waste Permit No. 0249-S1-R2
AFIN No.: 03-00051
Revision 2, 10/27/2010
Page 1 of 8
SECTION ONE
GENERAL INFORMATION
1.01
INTRODUCTION
The Northwest Arkansas Regional Solid Waste Management District owns and operates the NABORS
Landfill that includes Class 1 and Class 4 eligible waste disposable areas. The Class 1 Landfill operates
under the authority of the Arkansas Department of Environmental Quality (ADEQ) Permit Number 0249S1-R2 and the Class 4 Landfill operates under the authority of ADEQ Permit Number 0249-S4. Figure 1
includes the site location map.
The Landfill property is located in parts of Sections 26, 35, and 36, Township 21 North, Range 14 West, of
the Midway Quadrangle in Baxter County, Arkansas. The Landfill is located approximately 9 miles north
of Mountain Home, Arkansas and 1.5 miles east of Three Brothers, Arkansas. The Landfill property is
divided into three Phases; Phase 1, 2, and 3. Currently, the Landfill is operating in Phase 1. Phase 1 is
comprised of three areas, namely Areas 1-1, 1-2, and 1-3. Area 1-1 consists of a closed Class 1 and
Class 4 disposal areas.Area 1-2 is inactive disposal area at this time. Area 1-3 is currently active. Finally,
a permitted Class 4 disposal area located south of Areas 1-2 and 1-3 is currently active.
General Information:
•
Facility Name: NABORS Landfill
•
ADEQ Permit No.: Class 1: 0249-S1-R2, Active Class 4: 0249-S4, inactive Class 4 (east of Area
1-1): 0249-S4J
•
Facility Location: Portions of Section 26, 35, and 36, Township 21 North, Range 14 West,
Baxter County, Arkansas.
•
Owner/Operator: Northwest Arkansas Regional Solid Waste Management District
•
Contact Person: Mr. Jason Kincade
•
Address: 1305 Rossi Road, Mountain Home, Arkansas 72653
•
Phone: (870) 425-3213, FAX: (870) 425-2864
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Northstar Engineering Consultants, Inc.
NABORS Landfill, Baxter County, Arkansas
ADEQ – Solid Waste Permit No. 0249-S1-R2
AFIN No.: 03-00051
Revision 2, 10/27/2010
Page 2 of 8
Leachate is generated from all Class 1 areas on site including Area 1-1 that is currently closed. Table 1
shows a summary from the landfill records of collected leachate for the years 2007, 2008 and 2009.
Table 1
Annual Leachate Collection
Area
Year 2007
Year 2008 [1]
Year 2009
Area 1-1
108,870
79,400
189,000
Area 1-2
424,768
642,750
813,500
Area 1-3
329,964
728,400
1,160,500
Total
863,602
1,450,550
2,163,000
[1]: includes 130,200 gallons one time collection from Class 4 impoundment area.
NABORS Class 1 Landfill Annual Leachate Collection Trend
1,400,000
1,200,000
1,160,500
1,000,000
813,500
Gallons
800,000
Area 1-1
Area 1-2
Area 1-3
728,400
642,750
600,000
424,768
400,000
200,000
329,964
189,000
108,870
79,400
0
07
20
08
20
Year
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09
20
Northstar Engineering Consultants, Inc.
NABORS Landfill, Baxter County, Arkansas
ADEQ – Solid Waste Permit No. 0249-S1-R2
AFIN No.: 03-00051
Revision 2, 10/27/2010
Page 3 of 8
Leachate is collected from individual tanks around Class 1 landfill areas. Collected leachate is managed
as follows:
(1)
Transport for disposal at Public Waste Water Treatment Plant (PWWTP): Most of the leachate is
transported for disposal at a Public Waste Water Treatment Plant (PWWTP) in Springfield Missouri.
Some leachate was disposed of at the City of Mountain Home PWWTP.
(2)
On-site treatment through permitted reverse osmosis treatment plant: ADEQ Permit ARR0048631
(3)
Leachate recirculation: Portions of the leachate is recirculated back into the lined “Sub-Title D”
disposal cells.
(4)
On-site storage: Several 6,000 to 10,000 gallon above ground tanks are available on site for
temporary storage. The storage tanks are within reinforced concrete containment structures.
1.02
PURPOSE
The purpose of this report is to provide design information for a proposed zero discharge leachate holding
ponds to help NABORS manage the collected leachate. The ponds will be located north and east of Area
1-3 as shown on the site plan.
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Northstar Engineering Consultants, Inc.
NABORS Landfill, Baxter County, Arkansas
ADEQ – Solid Waste Permit No. 0249-S1-R2
AFIN No.: 03-00051
Revision 2, 10/27/2010
Page 4 of 8
SECTION TWO
LEACHATE HOLDING PONDS DESIGN
2.01
OBJECTIVE
The holding ponds will be used for the detention of collected leachate as part of the leachate
management plan for the landfill. Leachate generation and collection at the landfill is dependent on
active or open areas that receive waste and areas of the landfill that received final cover and
impermeable cap system. NABORS will be responsible for the collection and management of leachate
through out the active life of the disposal areas and for an additional 30 years of post-closure care of any
closed areas.
Summarized below are objectives for a successful design of the leachate holding ponds:
(1) Holding ponds to be designed with sufficient capacity for collected leachate and precipitation directly
into the ponds.
(2) Estimate evaporation rate from the ponds.
(3) Allow for a two-foot minimum freeboard.
(4) Allow for pond aeration.
(5) Design to allow for two pond system to allow for the consolidation of leachate in one pond to allow
for maintenance and cleaning of the other pond.
(6) Provide estimate of expected rate of leachate removal for treatment, disposal or other permitted
management methods.
(7) Leachate will continue to be collected in leachate collection tanks around areas 1-1, 1-2 and 1-3.
Individual tanks will be pumped periodically and transported to the proposed leachate holding ponds.
(8) Leachate in the holding ponds will be managed by periodically pumping leachate into the landfill’s
leachate tanker or contract tanker to transport to a Public Waste Water Treatment Plant. Currently
leachate is transported and disposed at the City of Mountain Home PWWTP and Springfield,
Missouri PWWTP.
(9) Long-term plans for leachate management include connecting the leachate tanks around the landfill
into a central lift station connected to the leachate holding ponds. NABORS plans to utilize future
methane gas collection system for possible leachate evaporation process.
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Northstar Engineering Consultants, Inc.
2.02
NABORS Landfill, Baxter County, Arkansas
ADEQ – Solid Waste Permit No. 0249-S1-R2
AFIN No.: 03-00051
Revision 2, 10/27/2010
Page 5 of 8
GENERAL PONDS DESIGN
(1)
The design calls for two interconnected leachate holding ponds, namely pond “A” and “B”. The
Latitude and Longitude coordinates to the center of each pond are 36° 27' 56.7” and 92° 26' 31.02”
for pond “A” and 36° 27' 55.8” and 92° 26' 32.94” f or pond “B'.
(2)
Ponds depth varies from 5 feet at the shallow end to 8 feet at the sump.
(3)
Side slopes are 3 feet horizontal to 1-foot vertical (3:1).
(4)
Access road and run-on control ditches along the perimeter of the ponds.
(5)
Ponds area is controlled with a 6-foot high gated chain link fence.
(6)
Ponds are lined with 60 mil smooth High Density Polyethylene (HDPE) liner underlain by
geosynthetic clay liner layer (GCL) on top of 2 feet of compacted soil clay liner to a permeability of 1
-7
-5
x10 cm / second and a lower two-foot clay liner layer compacted to a permeability of 1 x 10
cm/sec.
(7)
Ponds “A” and “B” are connected with 8-inch PVC SDR 26 with a valve.
(8)
Leachate delivery into holding ponds:
•
Leachate is pumped into a tanker trailer from the leachate collection tanks around Areas 11, 1-2 and 1-3.
•
Tanker trailer to deliver collected leachate into the leachate intake basin located southwest
of Pond “B”. Leachate is delivered into the basin by gravity.
•
Leachate intake basin is PVC 24-inch in diameter with removable cover. The basin extends
minimum one foot above adjacent finished grade. The minimum sump depth is 12-inches.
•
The sump is connected with an 8-inch PVC, SDR-26 pipe that discharges into Pond “B”.
The pipe outflow includes Uni-Flanged restraint and an 8x8x8-inch PVC Tee to direct the
discharge on the pond sloped embankment. Detail E on sheet 8 of the design plans shows
the leachate delivery system detail.
2.03
DESIGN AND ANALYSIS
2.03.1 PONDS SURFACE AREAS & VOLUME
(A) Surface Areas:
2
Top surface area per pond = 62,016 ft
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Northstar Engineering Consultants, Inc.
NABORS Landfill, Baxter County, Arkansas
ADEQ – Solid Waste Permit No. 0249-S1-R2
AFIN No.: 03-00051
Revision 2, 10/27/2010
Page 6 of 8
2
Bottom surface area per pond = 47,348 ft
The top surface area will be used for the calculation of evaporation rate.
(B) Volume:
3
Volume per pond up to maximum leachate surface elevation of 1074 = 209,291 ft or 1,565,602
gallons.
Volume per pond between maximum leachate surface elevation (1074) and free-board elevation
3
(1076) = 110,295 ft or 825,064 gallons
3
Total available volume without free-board (Ponds A & B) = 418,582 ft or 3,131,204 gallons
3
Total available volume including free-board (Ponds A & B) = 639,172 ft or 4,781,006 gallons
From Table 1 in Section 1, the landfill collected 2,163,000 gallons of leachate in 2009. For the
purpose of providing adequate holding capacity in the ponds, the total volume of collected
leachate is used without any deductions for disposal at PWWTP or storage on site. The design
capacity of the holding ponds without the freeboard volume is approximately 1.5 times the 2009
leachate collection volume.
2.03.2 PRECIPITATION
Appendix A includes copy of temperature and precipitation normals for the years 1971 to 2000 as
published by NOAA Southern Regional Climate Center for Station ID 035036 (Latitude 36.35
degrees and Longitude 92.39 degrees). The annual precipitation as reported was 45.23 inches.
2.03.3 EVAPORATION
Appendix B includes excerpts from NOAA Technical Reports NWS 33 and NWS 34.
The
estimated Pan Evaporation rate for Baxter County area for the annual period from May through
October is approximately 35.85 inches. A modified Evaporation rate (0.76 of Pan Evaporation
Rate) for the annual periods from May through October was used in the analysis.
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Northstar Engineering Consultants, Inc.
NABORS Landfill, Baxter County, Arkansas
ADEQ – Solid Waste Permit No. 0249-S1-R2
AFIN No.: 03-00051
Revision 2, 10/27/2010
Page 7 of 8
2.03.4 LEACHATE VOLUME
The high volume of collected leachate in 2009 is attributed to the following:
(a)
Area 1-1: The area was closed prior to 1993. The final cover system includes a compacted
clay layer. The average waste depth in this area is approximately 20 feet, with longitudinal
leachate collection system under the waste mass.
The longitudinal leachate collection
system includes lined trenches filled with washed gravel.
The longitudinal leachate
collection trenches are connected with a lateral leachate collection trench along the toe of
the waste mass. Soil cover over the lateral trenches is approximately 2 to 3 feet deep. The
leachate collection system receives significant amounts of infiltration.
(b)
Area 1-2: The area is not active at this time and a permanent impermeable final cover (cap)
system is not installed at this time. A depressed area on top of Area 1-2 is allowing for the
collection of run-off and precipitation, which ultimately is collected as leachate.
(c)
Area 1-3: Cells 1 and 2 are active and continue to receive waste. Significant amount of
storm water collected in the leachate collection system prior to the opening of Cell 2.
2.03.5 CONCLUSIONS OF ANALYSIS
Appendix C includes a spreadsheet showing the anticipated performance of one pond when
allowing for precipitation, leachate addition and evaporation. The analysis shows the following:
A)
Based on the 2009 reported total collected leachate volume of 2,162,000 gallons, both
ponds “A” and “B” will be required for containment. The estimated net holding capacity of
both ponds less precipitation volume and including evaporation volume = (2) x (1,565,602
gallons - 1,748,439.83 + 804,127) = 1,242,578.34 gallons. Similarly, the net holding capacity
of both ponds including free board volume = (2) x (2,390,666 – 1,748,439.83 + 804,127) =
2,892,706.34 gallons.
B)
Assuming nothing changes on site concerning reduction of leachate generation, then the
landfill will not have sufficient holding capacities in the ponds.
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Northstar Engineering Consultants, Inc.
C)
NABORS Landfill, Baxter County, Arkansas
ADEQ – Solid Waste Permit No. 0249-S1-R2
AFIN No.: 03-00051
Revision 2, 10/27/2010
Page 8 of 8
Reduction in leachate collection rates is expected over the next years for the following
reasons:
i. Area 1-2: Closure activities to construct permanent final cover over Area 1-2 is planned to
be completed over the next three to four years. Immediate correction to depression
areas on top of Area 1-2 should be completed sooner.
ii. Area 1-3: Smaller new disposal cells will be open to the north of Cell 1. New cells will be
utilized as soon as they are approved for disposal to minimize the duration of open
areas receiving storm water infiltration into the leachate collection system.
ii. Leachate management plan for the landfill to include the utilization of the holding ponds,
leachate recirculation into permitted disposal cells, on-site treatment through the
reverse osmosis plant and off-site disposal to a permitted PWWTP.
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