APPX F_MEMO LANDFILL OPTION COST ESTIMATES 051809.DOC 1 MEMORANDUM 

# Planning-Level Cost Estimates for Landfill Options

TO: 

### Mike Dworsky, County of Hawai`i

COPIES: 

### Mark Dexter, HNL

FROM: 

### Dan Pitzler Cory Hinds

DATE: 

### March 27, 2009 This memorandum provides background for pl anning-level cost estimates of two landfill options: 1) transfer waste from East Hawai`i to the West Hawai`i Sanitary Landfill (WHSL) and 2) expanding the South Hilo Sanitary Landf ill (SHSL) in two phases, with the first phase consisting of a 7-acre lateral expansion of the existing landfill, and the second phase consisting of expanding the landfill into quarries adjacent to the SHSL site. It is intended to outline the rationale and assumptions for each option and assist the County in decision making about long-term disposal options. The cost estimates are shown on a per-ton ba sis for managing the waste currently disposedof at the County’s SHSL. An analysis of the County’s budget resulted in an estimated perton cost of landfilling at the SHSL of $57. 64 per ton in 2007-08. The estimated per-ton disposal cost of each landfill option follows, with a high-low cost range shown for the new landfill development options.

Per-ton Cost (2009$)
Landfill O p tions Low Hi g h Transfer waste from East Hawai`i to the WHSL $82
7-acre lateral expansion of SHSL $82 $94
Expand SHSL into Quarries $69 $73 

# 1. Transfer Waste from East Hawai`i to the WHSL

As shown in Exhibit 1, the estimated cost of transferring waste from East Hawai`i for disposal at the WHSL is $82 per ton.

EXHIBIT 1 Cost Summary – Transfer Waste from East Hawai`i to the WHSL

Cost Element 2009 Dollars per ton Transfer Station Operations $11.00 Transportation $24.00 Landfill Cost $47.00 Total $82.00PLANNING-LEVEL COST ESTIMATES FOR LANDFILL OPTIONS

APPX F_MEMO LANDFILL OPTION COST ESTIMATES 051809.DOC 2 

### For comparison, Table 3.2 of the 2004 Sort Station EIS 1 

### estimated the per-ton cost of transfer, transport, and disposal at $7.21, $18.83 and $34. 83, respectively, for a per-ton total of $58.86. Escalating those costs from 2003 to 2008 using Engineering News Record’s Construction Cost Index, would increase that estimate by 29 percent to $75.93 per ton, or about 7 percent less than the estimate shown in Exhibit 1. Planning-level operating costs for a transfer operation at the SHSL Sort Station are presented in Exhibit 2. These costs include an estimate of the labor (FTEs) and equipment necessary to operate the station. The estimated cost of transporting waste from the Sort Station to the WHSL is shown in Exhibit 3. These estimates are based on a tr ucking cost model used by CH2M HILL on recent similar projects, with input parameters adjusted to reflect specific conditions that apply in Hawai`i County. The estimate also includes an adjustment to account for the assumption that waste would be hauled direct ly from the Pahoa Recycling and Transfer Station to the WHSL instead of to the SHSL for transfer; this cost adjustment is based on the County’s 2007-08 actual per-mile trucking cost . Exhibit 4 presents the assumptions used to estimate the number of tractor trailers needed for the trucking operation. The estimated variable per-ton cost for landfillin g at the WHSL is calculated based on actual 2007-08 costs as shown in Exhibit 5. It was assu med that no additional County staff would be needed at the WHSL to accommodate the in crease in waste from East Hawai`i. Should additional workers be required, the unit costs would be higher than shown. Other cost considerations relevant to this option that are not included in these cost estimates include:

• No costs have been included for environmen tal review, transportation improvements or mitigation. Depending on the transportation ro ute selected from the Sort Station to the WHSL, and the number and types of permits and studies required, it’s possible that additional costs would be incurred to address these considerations.

• Landfilling waste from East Hawai`i at the WH SL will shorten the life of that landfill. Long-term disposal forecasts (that take into account population and employment growth and the effect of planned diversion programs) are that the WHSL has an additional 38 years of capacity remaining 2 

### . If waste from East Hawai`i is added starting in 2013-14 (the time when the SHSL is likely to close if it is not expanded), the WHSL’s capacity would be exhausted in 27 years, or 11 years sooner.

1 County of Hawai`i. 2004

. Final Environmental Impact Statement, Constructi on and Operation of the East Hawai`i Regional Sort Station.

2 The County is currently investigating options to extend the years of remaining capacity at the WSHL. These options would be evaluated as part of the WHSL master plan proposed fo r implementation as part of this ISWMP Update.PLANNING-LEVEL COST ESTIMATES FOR LANDFILL OPTIONS

APPX F_MEMO LANDFILL OPTION COST ESTIMATES 051809.DOC 3

EXHIBIT 2 Transfer Station Operating Cost
Notes Typical Annual Tonnage 80,000 TS Operating hours
per year 3,801 10.5 hours per day per week 73 Days per year 362 tons per day 221 Annual tons / 362

Peak hour tons 44 Conceptual "rule of thumb" - 20 percent in peak hour Peak hour trailers 2 Assumes 18 tons per trailer
Blended Labor rate
Site attendants $49,885 2008-09 cost times 36 percent benefits (percent estimated from actuals) Equipment operator $62,206 2008-09 cost times 36 percent benefits (percent estimated from actuals) Staffing CH2M HILL Estimates Trailer Shuttle 1 $62,206 $62,206 Dozer 1 $62,206 $62,206 Site attendant at main building 2 $49,885 $99,770 Scale attendant 1 $62,206 $62,206 Extra FTE for illness/vacation 0.4 $22,030 Total Staff 5.4 $308,419 Multiplier for >40 hours per wk 1.8 Total FTEs 10.0 $563,606

Annual staffing $563,606
Non-labor percent 60 percent CH2M HILL estimate for this type of facility

Non-labor cost $338,163 Equipment replacement and operations, fuel, insurance, utilities, general site maintenance
Total $900,000 $/ton disposed $11.25 Total / tons per year Staff per operating hour 5.5 Avg number of staff on-site at one timePLANNING-LEVEL COST ESTIMATES FOR LANDFILL OPTIONS

APPX F_MEMO LANDFILL OPTION COST ESTIMATES 051809.DOC 4

EXHIBIT 3 Trucking Cost Estimate Operating Assumptions Equipment Cost
Origin Location SHSL Tractor (truck) Make and Model County Actuals Destination WHSL Number of Tractors in the Fleet 7.0 Miles (one way) 77.5 Annual Lease $24,000 Average Miles per Hour 40 Total Tractor Cost $168,000 Workdays per Week 7 Annual Workdays 362 Trailer Make and Model Tri-axle Trailer Monthly Tons through the T/S 6,682 Number of Trailers in the Fleet 14 Annual Trips 4,455 Annual Lease $11,000 Average Tons per Trip 18 Total Trailer Financed Cost $154,000 Compacted / Uncompacted Loads Uncompacted Average Loading Time 20 Total Tractor and Trailer Lease $322,000 Average Unloading Time 20 Average Roundtrip Time 3.88 Required Tractor Quantity 7.0 Total Time per Trip 4.54 Required Trailer Quantity 14 Loads per day 12
Licenses & Taxes Labor Assumptions State Highway Use Tax n.a. Non-driving percent 0 percent State Hawai`i Driver hours per day 56 Rate per mile n.a. Hostler hours per day 0 State An. Registration (per truck) n.a. Total hours per day 56 Driver Annual Wage $45,740 Federal Hwy Use Tax (per truck) $550 Loaded Driver Percentage 36 percent Insurance (per truck per year) $1,000 Annual Insurance $7,000
Fuel Cost
Fuel MPG 5.0 Operational Assumptions Diesel Cost per Gallon $4.00 SG&A Overhead Percentage 0 percent (SG&A is Sales / Mgmt / Admin / Dispatch) Repair & Maintenance Profit Margin Percentage 0 percent Truck Cost per Mile $0.30 Interest Rate 5.00 percent Trailer Cost per Mile $0.22 Annual Cost

per Truck Annual Trucking Costs Cost per Ton Cost per Mile
Truck $24,000 $168,000 $2.10 $0.49 Trailer $11,000 $154,000 $1.92 $0.45 Labor $605,060 $7.55 $1.75 Fuel $552,374 $6.89 $1.60 R&M $359,043 $4.48 $1.04 Insurance $14,000 $0.17 $0.04 License & Fees $0 $0.00 $0.00 G&A $0 $0.00 $0.00 Profit $0 $0.00 $0.00 Total $1,852,478 $23.10 $5.37 Direct haul from Pahoa TS to WHSL $106,000
Total tons 81,487 Total per ton cost $24.03PLANNING-LEVEL COST ESTIMATES FOR LANDFILL OPTIONS

APPX F_MEMO LANDFILL OPTION COST ESTIMATES 051809.DOC 5

EXHIBIT 4 Estimated Number of Tractors Needed to Haul to WHSL Origin Location SHSL Destination WHSL Miles (one way) 77.5 Average speed (miles per hour) 40 Workdays per week 7 Annual workdays 362 Monthly tons throughput 6,682 Average tons per trip 18 Compacted / Uncompacted Loads Uncompacted Average loading time (mins.) 20 Average unloading time (mins.) 20 Average roundtrip driving time 3.9 Total time per trip (hrs.) 4.54 Hrs per day of tractor operations 10 Trips per truck/day 2.20 Spare 1.0 No. of tractors needed per shift 6.6

EXHIBIT 5 Estimated Variable Landfilling Cost at the WHSL $ per ton Contract costs $42.97 Contract escalation $0.97 Fuel $1.59 Parts $1.73 Total variable cost $47.26



# 2. SHSL Expansion

The cost of expanding the South Hilo Sanitary Landfill is less certain than the cost of transporting waste to the WHSL. Thus discussi on of this option is based upon certain assumptions regarding feasibility, and the cost estimates as presented have some degree of uncertainty. Additional analysis would be need ed to further refine the cost estimates and confirm the feasibility of this option. Expansion of the SHSL could potentially be a ccomplished in two separate phases: first, a 7-acre lateral expansion to the northwest; an d second, a larger-scale expansion into rock quarries located adjacent to the southeast pe rimeter of the site. A discussion of the two possible expansion areas follows. 

## Seven-Acre Lateral Expansion to the Northwest It is assumed that the initial expansion would occur on a 7-acre vacant land parcel which borders the SHSL to the northwest. It was initially assumed that expansion into this areaPLANNING-LEVEL COST ESTIMATES FOR LANDFILL OPTIONS

APPX F_MEMO LANDFILL OPTION COST ESTIMATES 051809.DOC 6 

### would also allow the County to increase the el evation of a portion of the existing landfill, and an initial estimate of the capacity that woul d be added by this expansion is just less than 2 million cubic yards 3 

### . At 2007-08 fill rates (about 250,000 cubic yards per year), this would have provided about 8 years of added capacity . However, the County recently received an unfavorable opinion from the Fe deral Aviation Administration that would limit the extent to which the SHSL could be expanded vertically . Thus, it is now anticipated that the lined expansion on this parcel would provide only an additional 4 years of capacity. State and federal regulations (Hawai’i Admini strative Rules [HAR], Title 11, Chapter 58.1 and 40 CFR 258.48) require that all new landf ills be constructed with a waste containment system consisting of a bottom liner with leac hate collection and recovery system. The liner system would consist of two layers of heav y duty plastic geomembrane, placed above and below a geosynthetic clay liner. The bottom of the new landfill cell would also have an engineered drainage layer. In addition, an exp ansion of the County’s existing groundwater monitoring program would probably be required.


### Estimated Capital Cost
The estimated construction cost for the 7-acre lined cell is $3.2 million 4 

### . To this estimate must be added the cost of a leachate colle ction and treatment system, a landfill gas collection system, and added groundwater mo nitoring. In regions with high annual precipitation rates higher volumes of leachat e are produced and must be managed. In response, Hawai`i County should consider taki ng steps to actively reduce the volume of leachate generated in the lined expansion by maintaining a system of plastic membranes and tarps to cover the waste. When the waste is covered by membranes or tarps, infiltration of precipitation can be mitigated and ru noff can be managed as storm water. Even with the use of membrane and tarp cove rs, leachate will be generated that requires treatment. Leachate that collects on the landf ill liner would be pumped out of the cell, and then treated prior to discharge. Treatment opti ons include treatment at the local wastewater treatment plant (WWTP) near the Hilo Airport, and treatment using constructed wetlands. Treating leachate at the WWTP would be costly because it would involve either constructing a lengthy pipeline or trucking leachate to the WWTP. Further, the County wastewater division prefers that other options be consid ered for leachate treatment: thus, the County investigated the feasibility of wetlands treatm ent. An initial feasibilit y evaluation indicated that wetlands treatment could effectively treat the leachate 5 

### . Additional assessment has been completed since the initial evaluation, resu lting in a range of cost estimates for the use of constructed wetlands for leachate treatment. Estimated costs for leachate treatment using constructed wetlands for leachate treatment for four scenarios are presented in Exhibit 6.

3 "South Hilo Sanitary Landfill Proposed Expansion Feasib ility and Capital Cost Estimate". 2008. SWT Engineers. 4 ibid. plus 10 percent engineer ing and 8 percent permitting. 5 CH2M HILL. 2008. South Hilo Sanitary Landfill Leachate Quality Impr ovement Using Treatment Wetlands – High Level Sizing and Cost Opinion . Technical Memorandum to SWT Engineering



### .PLANNING-LEVEL COST ESTIMATES FOR LANDFILL OPTIONS

APPX F_MEMO LANDFILL OPTION COST ESTIMATES 051809.DOC 7

EXHIBIT 6 Estimated Capital Cost of Constructed Wetland Leachate Treatment at SHSL

Surface Flow Wetland Vertical Subsurface Flow Wetland

Scenario Cover Scenario Fill Plan Design Flows Equalization Tank (gallons) Wetland Size (acres) Capital Cost Wetland Size (acres) Capital Cost

1 Aggressive: 60 percent

cover Three 15- foot lifts Avg annual - 5.5 gpm 60,000 1.2 $1,610,000 0.2 $1,801,000

2 Moderate: 35 percent

cover Three 15- foot lifts Avg annual - 8.9 gpm 60,000 1.5 $1,983,000 0.3 $1,956,000

3 No cover One 15- foot lift Avg annual - 13.5 gpm 60,000 2.3 $2,261,000 0.6 $2,398,000

4 No cover One 15- foot lift Peak monthly - 82 gpm 300,000 10 $6,677,000 1.8 $4,847,000

Source: CH2M HILL, 2009. 

### As shown in Exhibit 6, at this level of analysis there are a number of uncertainties about the sizing and cost of using constructed wetl ands for leachate treatment. Wetland sizing depends on contaminant and hydraulic loading rates. Contaminant loading rates for the short-term expansion into the 7-acre parc el are unknown, but were assumed using a combination of data from "wet" landfills in Oregon and Alaska and existing data from a landfill on Oahu 6 

### . Based on data from a high-rainf all landfill in Unalaska, Alaska, contaminant loading rates were decreased by 50 percent during peak flows to account for dilution. The contaminant loading used in this analysis is likely to be conservative because actual dilution from rainfall at the SHSL may be higher. Because the exact data for contaminant loading is unknown, it is not certain at this stage whether smaller size wetlands would provide sufficient reside nce time for treatment. Hydraulic loading refers to the rate of leachate generation in the landfill liner. Leachate flow rate depends on liner area, climate inputs (e.g ., rainfall and evaporation), cover used during operations to divert storm water, and thickne ss of in-place waste. The design flows for the scenarios shown in Exhibit 6 were estimated using the EPA HELP model 7 

### . Application of more membrane and tarps to divert storm water has the potential to decrease leachate generation and require a smaller wetland footpr int for treatment. The most conservative estimate for wetland sizing and cost is Scenar io 4 with no cover to divert storm water, a single 15-foot lift of waste in place over th e entire cell, an equalization tank sized to accommodate the 10-year peak daily flow, and wetlands sized to accommodate peak monthly precipitation yielding a high leachate flow rate of 82 gpm. Less conservative

6 County of Hawai`i. 2004. Final Environmental Impact Statement, Constructi on and Operation of the East Hawai`i Regional Sort Station. 7 CH2M HILL. 2008 . Estimate of Leachate Generation Rate for Propos ed Lined Lateral Expansion of Hawai`i County’s Hilo Landfill. Technical Memorandum to SWT Engineering.PLANNING-LEVEL COST ESTIMATES FOR LANDFILL OPTIONS

APPX F_MEMO LANDFILL OPTION COST ESTIMATES 051809.DOC 8 

### scenarios assume more cover and the associated diversion of storm water, less generation of leachate, a smaller equalization tank, and smaller wetland sizing and the associated costs. Wetland sizing also depends on regulatory endpoints and compliance frequency. More stringent regulatory requirements typically re quire higher residence time in the treatment wetlands and larger size and cost. The wetland s treatment option assu mes surface discharge of treated leachate and subsequent infiltration and migration to groundwater. Testing of treated effluent would be conducted to confir m regulatory requirements prior to discharge, and groundwater monitoring would be conducte d to confirm that leachate discharge is not negatively impacting the shallow aquifer. For planning purposes it was assumed that leachate discharged from wetlands would contain lower concentrations of contaminant s than are presently discharged in leachate infiltrating the subsurface from the existing unlined landfill. Leachate discharge regulatory criteria assumed for the current sizing are as follows: less than 200 milligrams per liter (mg/L) biological oxygen demand (BOD5), less than 25 mg/L total suspended solids (TSS), and less than 10 mg/L ammonia-nitrogen ( NH4-N) and nitrate+nitrite- nitrogen (NOx-N). If actual regulatory endpoints are stricter than this, then required wetland size and cost would increase. Similarly, if monthly average complianc e is permitted, then required size and cost would be smaller than if daily compliance is mandated. Potential additional steps to evaluate regula tory compliance issues, and how they affect wetland size and design would include the following:

• Conduct a more thorough evaluation of co ntaminant loading for the potential lined expansions of the SHSL.

• Conduct modeling of specific treatment we tland processes to select minimum size
treatment area.

• Meet with staff from the State of Hawa i`i Department of Health Environmental Management Division, Clean Water Branch to evaluate regulatory requirements and discharge criteria for wetlands leachate treatment. The lined expansion would require a system to collect and manage landfill gas. The type of system, active or passive, would depend on th e landfill gas system selected for the unlined portion of the landfill and a series of other fact ors. Thus, Exhibit 7 includes a passive control system as a low estimate, and an active control system as a high estimate. The estimate is only for the 7-acre expansion to the northwest of the existing landfill.


### Operations and Maintenance Costs In is anticipated that County staff levels for day-to-day operations would be similar to its current operations. O&M costs expected to incr ease include costs associated with diverting rainfall from waste, managing leachate, and additional monitoring and regulatory compliance.
In Scenario 2 of Exhibit 6, it is assumed that capital costs to procure tarping, and labor costs for one extra FTE would be required. In Scenario 4, it is assumed that no extra effort would be made to divert rainfall from waste.PLANNING-LEVEL COST ESTIMATES FOR LANDFILL OPTIONS

APPX F_MEMO LANDFILL OPTION COST ESTIMATES 051809.DOC 9 

### Estimated additional annual costs for pump ing leachate, groundwater monitoring, and a weekly walk through of the wetlands treatment system are $100,000 in Scenario 2 and $200,000 for Scenario 4.

EXHIBIT 7 Landfill Gas Cost Estimates 328,000 Tons from 7-acre expansion 0.46 Tons per cubic meter 150,464 Cubic meters from 7-acre expansion

0.00047 SCFM per cubic meter 70.95901 SCFM

Low - Passive System
$0.31 $ per cubic meter (escalated for Hawai`i with 10 percent engineering) $47,000 Landfill gas cost for 7-acre expansion

$4,700 Annual O&M (10 percent of capital)

High - Active System Collection system $0.60 $ per cubic meter (escalated for Hawai`i with 10 percent engineering) $90,000 Landfill gas collection syst em cost for 7-acre expansion Flare system $600,000 $ per 1,000 scfm $123,000 Flare system capital cost for 7-acre expansion Total Active System $213,000 Sum of collection system and flare system costs

$21,000 Annual O&M (10 percent of capital) Source: CH2M HILL, 2009.



### Periodic major maintenance of the wetland treatment system would be required, which could include replacing the equalization tank, re construction or cleanout of wetland cells, and/or development of a new infiltration ba sin. These costs are estimated to occur approximately every 6 years at a cost of $250,000 for Scenario 2 and about $900,000 for Scenario 4. Finally, it is estimated that three new monitori ng wells would be constructed at a cost of $15,000 per well. Based on current County monitoring costs, it is assumed that it would cost an additional $7,500 per well annually, for a total of $22,500 per year in additional groundwater monitoring costs.



### Closure and Post-Closure Costs The SWT report (Table 3) estimates the adde d closure cost for the 7-acre extension of $1,156,000. Post-closure cost estimates are sh own in Exhibit 8: the low estimate assumes passive landfill gas collection, and the high es timate assumes active landfill gas collection. When the extension is closed, it is assumed that any residual leachate would be treated along with leachate from the expansion into the quarries, with the costs included as part of that expansion.PLANNING-LEVEL COST ESTIMATES FOR LANDFILL OPTIONS

APPX F_MEMO LANDFILL OPTION COST ESTIMATES 051809.DOC 10

EXHIBIT 8 Post-closure Cost Estimates for 7-Acre Expansion Annual cost

Item Qty Unit Unit cost Low High Inspections 7 acre $260 $2,000 $2,000 Final cover 7 acre $1,300 $9,000 $9,000 Surface water management 7 acre $1,300 $9,000 $9,000 Vegetation 7 acre $390 $3,000 $3,000 Gas management $5,000 $21,000 Environmental monitoring groundwater 3 wells $7,500 $23,000 $23,000 landfill gas 7 acre $780 $5,000 $5,000 leachate 7 acre $260 $2,000 $2,000
stormwater 7 acre $260 $2,000 $2,000 Inspections 7 acre $260 $2,000 $2,000 Total $55,000 $71,000 Source: CH2M HILL, 2009. 

### Per ton costs of 7-Acre Expansion A low and high range of per-ton costs for the 7-acre expansion is shown in Exhibit 9. As shown, the costs are expected to range from between $82 and $94 per ton for approximately 4 years of added capacity.

EXHIBIT 9 Per-ton Costs of 7-Acre Expansion (2009$) Low High Capital Costs (7-acre cell only) Expansion - constructi on $3,200,160 $3,200,160 Leachate treatment system (wetlands) construction $1,956, 000 $4,847,000 Landfill gas collection $47,000 $213,000 Groundwater wells $45,000 $45,000 Closure $1,156,000 $1,156,000 Total Capital Cost $6,404,160 $9,461,160 O&M Costs (7-acre cell only) Landfill stormwater management $60,000 $0 Leachate O&M $100,000 $200,000 Leachate treatment upgrades (annual) $42,000 $103,000 Added groundwater monitoring $23,000 $23,000 Annual post closure care a $277,000 $333,000 Total O&M Cost $502,000 $659,000 Total capacity of expansio n (tons) 328,000 328,000 Added per ton costs Capital $19.52 $28.85 O&M $6.12 $8.04 Total $25.65 $36.88 Current (2007-08) per ton cost $56.74 $56.74 Estimated per-ton cost of SH Lat eral Expansion $82.39 $93.62

a Assumes all funds are collected up front prior to clos ure and invested in a fund that is drawn down to zeor over a 30-year peri od (i.e., a sinking fund).PLANNING-LEVEL COST ESTIMATES FOR LANDFILL OPTIONS

APPX F_MEMO LANDFILL OPTION COST ESTIMATES 051809.DOC 11 

### The estimates assume that all funds for post-clo sure are collected up front in a sinking fund where the funds collect interest, and are then paid out during the 30-year post-closure period. While the County would probably fund post-closure differently, this approach is conservative. The costs shown are conservative be cause it is assumed that all costs would be spent at once, whereas the costs of post-closu re (and the landfill gas system) would not be spent until the expansion is at capacity. In ot her words, the County could set aside a smaller sum into an interest-bearing account, and then spend them when needed. 

## Expansion into the Quar ries at the SHSL Site If constructed, the 7-acre expansion to the northwest of the current SHSL would provide capacity until approximately 2016-17. At that time, the County would need new landfill capacity for residuals from East Hawai`i. Ha wai`i County owns several parcels of land currently used for quarry operations southeast of the existing landfill. The 75-acre quarry site is slightly larger than the existing l andfill footprint. Preliminary estimates are that development of this quarry site for future landfill operations wo uld provide 47 years of capacity beginning in 2017-18 when the 7-acre expansion is full 8



### . This larger expansion area would be construc ted and operated using the same assumptions noted above for the 7-acre northwest expansion (i.e., it assumes a liner system, constructed wetlands for leachate treatment, additional gr oundwater monitoring wells, an active landfill gas management, active stormwater managem ent to minimize leachate production, and final closure and post-c losure monitoring). It is assumed that the landfill would be operated as a series of 7-acre cells. When each cell is at capacity, it would be closed on an interim basis to minimize leachate generation. Thus, it is assumed that the constructed wetlands developed for the 7-acre northwest expansion would be of sufficient size to accommodate leac hate generated from the larger expansion to the southeast. It is assumed that the exis ting groundwater monitoring network would provide adequate coverage in the downgradient direction from the quarry expansion area, and that new monitoring wells would be needed along the east and west perimeter and upgradient edges of the new cells. It is assu med that the landfill wo uld eventually have an active landfill gas management system. Operatio ns are assumed to be similar to what was assumed for Scenario 2 (Exhibit 6) for the 7-ac re expansion (i.e., active steps would be taken to minimize leachate generation). It should be noted that no engineering analysis has yet been conducted for the quarry site. Thus, contingencies of 15 percent for the low estimate and 30 percent for the high estimate have been added to the capital costs to account for unknown conditions that could result in cost increases. In addition, expanding to the southeast into the quarry site would require a successful outcome of the State Land Use Boundary Amendment and County Zoning processes, completion of an Environmental Impa ct Statement, and resolution of Department of Health permitting issues. The estimated costs of landfilling in the quarry site are shown in Exhibit 10.

8 This estimate accounts for growth in population and employment and assumes pl anned diversion programs in this ISWMP Update are implemented. The life of the landfill would increase if additional diversion programs are implemented in future ISWMP updates.PLANNING-LEVEL COST ESTIMATES FOR LANDFILL OPTIONS

APPX F_MEMO LANDFILL OPTION COST ESTIMATES 051809.DOC 12

EXHIBIT 10 Per-ton Costs of Landfilling in Quarry Site (2009$) Capital Costs Low High Expansion – construction $34,287,000 $34,287,000 Leachate treatment system expansion $450,000 $700,000 Landfill gas collection $11,212,000 $11,212,000 Groundwater wells $135,000 $135,000 Closure $12,386,000 $12,386,000 Add contingency (15 percent/30 percent) $6,825,00 0 $13,650,000 Total Capital Cost a $65,362,000 $72,580,000 O&M Costs Landfill stormwater management $60,000 $0 Leachate O&M $100,000 $200,000 Leachate treatment upgrades (annual) $42,000 $103,000 Added groundwater monitoring b $34,000 $34,000 Annual post closure care c $99,000 $99,000 Total O&M Cost $335,000 $436,000 Total capacity of expansion (tons) 7,905,700 7,905,700 Added per ton costs Capital $8.27 $11.22 O&M $4.09 $5.32 Total $12.35 $16.54 Current (2007-08) per ton cost $56.74 $56.74 Estimated per-ton cost of SH Lat eral Expansion $69.03 $73.28

a Costs would be spent over the life of the facilit y as new cells are opened; closure costs would be spent once the landfill is at capacity.

b Midpoint of annual costs over life of landf ill as wells are progressively installed.

c Assumes all funds are collected up front prior to closure (sinking fund).