DISPOSAL SITE GAS MODELING STUDY. Shadra Disposal Site Agra, India

Transcription

1 DISPOSAL SITE GAS MODELING STUDY Agra, India Prepared for: Agra Municipal Corporation Prepared under the support of: U. S. Environmental Protection Agency Disposal Site Methane Outreach Program Prepared by: File No February 2010

2 Table of Contents Section Page 1.0 Executive Summary Introduction Purpose of the LFG Modeling Study Data Sources Background on the SCS International LFG Model Project Limitations Description of dump site Waste Disposal Information...4 Annual Waste Disposal Rates...4 Waste Composition Data Disposal Site Gas Generation and Recovery Projections Effects of Site Conditions on LFG Generation and Recovery Model Parameters...7 Model k Values...7 Methane Correction Factor...7 Model Lo Values...8 Collection Efficiency Model Results Conclusions... 9 Attachment a Aerial Photograph of... 1 Attachment B LFG Model Results... 2 List of Figures No. Page Figure 1. Photographs of -Phase I... 4 Figure 2. Photographs of -Phase II... 4 List of Tables No. Page Table 1. Waste Disposal Estimates... 5 Table 2. Waste Composition Data...6 List of Attachments Attachment A - Aerial Photograph of Attachment B - LFG Model Results i

3 DISPOSAL SITE GAS MODELING STUDY AGRA, INDIA 1.0 EXECUTIVE SUMMARY This Disposal Site gas (LFG) modeling study has been prepared by SCS Engineers (SCS) for the in Agra, India. The study was prepared based on the information provided by the Leadership for Environment and Development and observations made during site visits on October 22, The disposal site operated from approximately 1979 until 2009 as an open dump site and has approximately 473,450 metric tons (Mg) of solid waste in-place. An LFG recovery model was prepared based on the sites disposal histories, waste characterization, climate, and estimated achievable collection efficiencies. Based on the projected quantities of recoverable LFG, this report indicates that the site is not good candidate for an LFG recovery project. 2.0 INTRODUCTION This LFG modeling study for the has been prepared by SCS Engineers (SCS) for the U. S. EPA Disposal Site Methane Outreach Program (LMOP), as part of the EPA s Methane-to-Markets Program, an international initiative to help partner countries reduce global methane emissions. 2.1 PURPOSE OF THE LFG MODELING STUDY The overall purpose of this LFG modeling study is to perform a preliminary assessment of the amount of LFG available to be collected from the in order to determine whether there is any potential for developing an LFG project to collect and combust and/or utilize the LFG. This overall purpose is achieved through the pursuit of the following objectives: Summarize and evaluate available information on the disposal site, including physical characteristics, site management, and waste disposal data. Develop estimates of the amount of recoverable LFG. Provide recommendations on whether there is sufficient LFG available to pursue an LFG recovery project. 1

4 2.2 DATA SOURCES The following information which was used in the preparation of this report was provided in the form of a written questionnaire completed by Dr. Vijai Pratap Singh from the Leadership for Environment and Development or was based on observations during the site visit performed on October 22, 2009: Estimated site opening and closing dates. Estimated site areas and average waste depths. The site areas were adjusted and waste volumes calculated by SCS using scaled aerial photographs of the sites obtained using Google Earth (see Attachment A). Waste composition data. 2.3 BACKGROUND ON THE SCS INTERNATIONAL LFG MODEL SCS has developed a proprietary international LFG model that employs a first-order decay equation for estimating LFG generation based on annual waste disposal rates, the amount of methane one Mg of waste produces (Lo value), and the rate that waste decays and produces LFG (k value). The model k and Lo variables are based on estimated waste composition and local climate information. Data used for developing model input parameters are discussed in later sections of this report. The SCS International Model uses the same input variables (k and Lo) and is generally similar to the U.S. EPA s Disposal Site Gas Emissions Model (LandGEM). The most significant difference between the models is the assignment of multiple k and Lo values in the SCS International Model. While the simple (single k and Lo) first order decay equation used in LandGEM is appropriate for modeling U.S. Disposal Sites, it is SCS s opinion that LFG generation at sites in developing countries may not be adequately modeled using this approach, primarily due to the significantly different waste composition and site conditions which create different patterns of waste decay and LFG generation over time. The SCS International LFG model employs separate modules with different k and Lo values that separately calculate LFG generation from the different waste components. This multi-phased first-order decay model approach recognizes that the significant differences in the types of waste disposed in developing countries require changes to the model structure as well as to the values of the input variables. A similar approach has been adopted by the Inter-governmental Panel on Climate Change (IPCC), which released a Disposal Site methane generation model in 2006 that applies separate modules for four different waste categories IPCC, IPCC Spreadsheet for Estimating Methane Emissions from Solid Waste Disposal Sites. 2

5 LFG generation estimates produced by the model are used to project potential LFG recovery with the existing or proposed collection system based on the estimated collection efficiency. Collection efficiency, defined as the percentage of generated LFG that is recovered by the LFG extraction system, is affected by a number of factors, including: well design, waste depth, type of liner and cover, leachate management issues, Disposal Site management practices, and collection system operations. 2.4 PROJECT LIMITATIONS The information and predictions contained within this LFG modeling study are based on the data provided by the site owners and their consultants. Neither the U.S. EPA nor its contractors can take responsibility for the accuracy of this data. Measurements, assessments, and predictions presented in this report are based on the data and physical conditions of the Disposal Site observed at the time of the site visits. No warranty, express or implied, is made as to the professional opinions presented herein. Changes in the site property use and conditions (for example: variations in rainfall, water levels, Disposal Site operations, final cover systems, or other factors) may affect future gas recovery at the disposal site. The U.S. EPA and SCS Engineers do not guarantee the quantity or the quality of the available gas. 3.0 DESCRIPTION OF DUMP SITE The Site is located in Agra, India in the state of Uttar Pradesh. The climate in Agra is classified as continental. The 24-hour average temperature is 25.6 degrees C (78 degrees F). Average annual precipitation in Agra is 710 mm (28 inches), most of which falls in the monsoon months of July through September. 2 The Shadra Dump Site is divided into two phases. Phase I is owned by the AMC, and Phase II is owned by local farmers. The Site operated as an open dump that served the City of Agra (estimated 2010 population of 1.69 million 3 ) from about 1979 until it was closed in April Waste in Phase I was not compacted or covered while in operation, but since its closure in 2009 it has been compacted and capped with soil (Figure 1). Phase II is uncapped and ungraded (Figure 2) but is expected to be covered with a synthetic cap. 2. Source: 3. Source: 3

6 Figure 1. Photographs of -Phase I Figure 2. Photographs of -Phase II 3.1 WASTE DISPOSAL INFORMATION Annual Waste Disposal Rates The disposal site area was calculated using a scaled aerial photograph obtained from Google Earth to be 34,195 m 2 for Phase I and 16,296 m 2 for Phase II (total of 50,491 m 2 ). The volume of MSW was calculated using the scaled aerial photograph obtained from Google Earth, a reported maximum depth of 12 m, and AutoCADD software to be approximately 344,548 m 3 for Phase I and 128,904 m 3 for Phase II (total of 473,450 m 3 ). In-place waste density was estimated to be 1.0 Mg/m 3 after accounting for waste decay. Applying this density to the estimated waste volume results in an estimated total of 473,450 Mg of waste in place. 4

7 Waste disposal reportedly occurred between 1979 and April The estimated total amount of waste in place, and opening and closing years were used to develop an annual disposal history, which is provided in Table 1. Table 1. Waste Disposal Estimates Year Annual Disposal (Mg) Waste In Place (Mg) , , , , ,140 4, ,370 6, ,640 7, ,970 9, ,360 12, ,830 15, ,400 18, ,080 22, ,900 27, ,880 33, ,060 40, ,470 48, ,160 59, ,190 71, ,630 85, , , , , , , , , , , , , , , , , , , , ,450 5

8 Waste Composition Data Waste composition and moisture conditions in a Disposal Site are primary considerations when estimating LFG model Lo and k values. This report uses the waste composition data provided by Dr. Vijai Pratap Singh, modified to provide a more detailed breakdown of the general waste categories. The estimated waste composition percentages are summarized in Table 2. Table 2. Waste Composition Data Waste Material Estimated % Food 50.0% Garden waste 5.0% Construction and demolition waste 28.5% Paper 2.5% Textiles 2.5% Metals 1.0% Wood waste 5.0% Plastics 5.0% Glass and ceramics 0.5% Total 100.0% Organic Fraction (wet basis) 65.0% Organic Fraction (dry basis) 26.6% Source: Dr. Vijai Pratap Singh from the Leadership for Environment and Development 4.0 DISPOSAL SITE GAS GENERATION AND RECOVERY PROJECTIONS The first-order decay model used for estimating LFG generation and recovery at Disposal Sites in developing countries has been described in a previous section of this report. The procedure used for estimating model Lo and k values that are appropriate for local site conditions has been documented in assessment reports and pre-feasibility studies prepared by SCS for LMOP and the M2M program. Adjustments to the Lo value account for the organic and dry solids content of wastes disposed. Adjustments to k value involve assigning separate k values to different waste fractions based on estimated decay rates. Additional adjustments to account for information specific to conditions at the are discussed below. Projections of LFG recovery can be calculated using model outputs of generation and estimates of percent collection system efficiency, a measure of the performance of the collection system in effectively capturing LFG. For sites without a collection system installed, collection efficiency estimates are based on an assessment of site conditions, including disposal area configuration, 6

9 disposal area sequencing, waste depth, soil cover, depth to leachate, and the presence of scavengers. 4.1 EFFECTS OF SITE CONDITIONS ON LFG GENERATION AND RECOVERY Site conditions at the disposal site can impact LFG recovery either indirectly (by their effects on LFG generation) or directly (by their effects on achievable collection efficiency). Site conditions impacting LFG generation and recovery which were considered in the development of the model estimates are summarized below: Moisture conditions. Annual average precipitation was used to evaluate moisture conditions at the disposal site and to estimate appropriate model k values. According to annual average precipitation in Agra is approximately 710 mm (28 inches). Disposal site management practices. The site was operated as an open dump. Shallow, uncovered waste piles typically experience aerobic conditions near the surface and will generate significantly less methane than managed sites that control the size of the active disposal area, compact waste, and apply soil cover on a frequent basis. This effect is accounted for in the model by modifying the Lo values through the application of a methane correction factor (MCF) that is assigned based on the estimated fraction of waste which decays aerobically and does not produce methane. The historically poor conditions also tend to contribute to low collection efficiencies that typically occur when wellfields are installed in shallow, uncompacted waste with high leachate levels. Phase I has been remediated, but phase II will need to be remediated prior to the installation of a gas collection system. Remediation would include waste consolidation, re-grading, and final cover installation. Additional discussion of model inputs and assumptions that reflect conditions at the Shadra Disposal Site are provided in the following section. 4.2 MODEL PARAMETERS Model k Values Based on the precipitation rate and estimated waste moisture conditions at the sites, SCS assigned the model k values of 0.2, 0.04, and 0.01 per year for the fast, medium, and slowly decaying organic waste fractions, respectively. Methane Correction Factor Based on an assessment of the effects of historic site management practices, a MCF of 0.8 was assigned to the site to account for aerobic waste decay resulting from shallow open dumping of waste. The MCF adjustment was applied to the Lo values used in LFG model. 7

10 Model Lo Values Waste composition data was used to estimate Lo values for the fast, medium, and slowly decaying organic waste categories at both disposal sites, based on the dry organic content of the disposed waste (as compared to average U.S. waste) multiplied by the estimated MCF. Separate Lo values were calculated for the different organic waste categories which are as follows (after applying a MCF of 0.8): Fast-decay waste (food and a portion of the garden waste): 58 m 3 /Mg. Medium-decay waste (paper, textiles, and a portion of the garden waste): 150 m 3 /Mg. Slow-decay waste (wood): 147 m 3 /Mg. The fraction of waste consisting of inert materials (e.g., construction and demolition waste, metals, plastics, glass and ceramics) was assigned an Lo value of 0 as it is not expected to contribute to LFG generation. Collection Efficiency As discussed above, conditions in Phase II of the Disposal Site would be expected to limit the efficiency any collection system to low levels and would require site remediation before system installation. Even after site remediation, achievable collection efficiencies would remain low due to the small volume and shallow waste depth. In addition, removal and re-depositing waste materials during grading and consolidation will create aerobic conditions that will lower LFG generation. Three LFG recovery scenarios were developed to reflect a range of achievable collection efficiencies that vary depending on the level of effort and amount of resources available to operate the collection systems. All three scenarios assume that Phase II of the Disposal Site would be substantially remediated prior to system installation, and that a relatively comprehensive system will be installed and begin operating in The three recovery scenarios are described as follows: 1. The low recovery scenario assumes that a moderate level of skill and effort is employed in the operation and maintenance of the collection system (e.g., including wellfield monitoring and adjustment about once per month). Collection efficiency is assumed to be 35 percent in all years starting in The Project Team considers the low recovery estimates to be conservative and should be employed only if a large margin of safety is needed. 2. The mid-range recovery scenario assumes that a moderately high level of skill and effort is employed in the operation and maintenance of the collection system (e.g., including wellfield monitoring and adjustment 2 to 3 times per month). Collection efficiency is assumed to be 50 percent in all years starting in The Project Team considers the mid-range recovery scenario to be its best estimates of likely recovery and recommends its use in the economic evaluation. 3. The high recovery scenario assumes that highest possible level of skill and effort is employed in the operation and maintenance of the collection system (e.g., including 8

11 weekly or more frequent wellfield monitoring and adjustment). Collection efficiency is assumed to be 60 percent in all years starting in The Project Team considers the high recovery estimates to be ambitious and attainable only if the maintenance of an optimal LFG recovery system is considered to be a top priority. Note that, in addition to the potential variability in collection efficiency and the level of operation and maintenance, mathematical modeling of LFG is inherently uncertain. The Project Team considered (and tried to account for) this modeling uncertainty in selecting the values for the high and low recovery scenarios when projecting LFG recovery rates. 4.3 MODEL RESULTS LFG generation projections for the are provided in Table B-1 and Figure B- 1 in Attachment B. LFG recovery projections under alternative collection system efficiency scenarios (low, mid-range, and high) are provided in Tables B-1 and B-2 and Figure B-1 in Attachment B. As shown in Table B-1, projected LFG generation has been declining from a high of 313 m 3 /hour (184 cfm) since LFG generation is projected to be 294 m 3 /hour (173 cfm) in 2010 and 248 m 3 /hour (146 cfm) in Under the mid-range collection efficiency scenario, LFG recovery is projected to decline from 105 m 3 /hour (62 cfm) in 2012 to 89 m 3 /hour (52 cfm) in 2013, and continue to decline thereafter due to declining LFG generation. Table B-1 also shows that the potential for power generation from LFG is estimated to decline from a maximum of 173 kw per hour in 2012 under the midrange recovery projections. The potential for emission reduction credits (CERs) through the combustion of landfill methane under the mid-range recovery projections is estimated to be 6,912 Mg of carbon dioxide equivalent (CO 2 e) emissions in 2012 and 5,865 Mg CO 2 e emissions in CONCLUSIONS The volumes of waste estimated to be present at the are too small to produce enough LFG for a viable LFG project. In addition, conditions would limit LFG recovery to a relatively small fraction of the very limited amount of LFG generated. Site remediation would be required before installing a gas collection system in the Phase II section and would improve local environmental conditions, but achievable collection efficiencies would likely remain low due to shallow waste depths. Therefore, a viable LFG recovery project is not possible at the. 9

12 ATTACHMENT A AERIAL PHOTOGRAPH OF SHADRA DISPOSAL SITE

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14 ATTACHMENT B LFG MODEL RESULTS

15 TABLE B-1 PROJECTION OF LANDFILL GAS GENERATION AND RECOVERY UNDER MID-RANGE SCENARIO SHADRA LANDFILL, AGRA, INDIA MID-RANGE RECOVERY SCENARIO Disposal Refuse LFG Collection Predicted LFG Maximum Baseline** Methane Emissions Rate In-Place Generation System Recovery Power Plant LFG Flow Reduction Estimates** Year (Mg/yr) (Mg) (m 3 /hr) (cfm) (mmbtu/hr) Efficiency (%) (m 3 /hr) (cfm) (mmbtu/hr) Capacity* (kw) (m 3 /hr) CH4/yr) CO 2 eq/yr) % % , % , % , % , % ,140 4, % ,370 6, % ,640 7, % ,970 9, % ,360 12, % ,830 15, % ,400 18, % ,080 22, % ,900 27, % ,880 33, % ,060 40, % ,470 48, % ,160 59, % ,190 71, % ,630 85, % , , % , , % , , % , , % , , % , , % , , % , , % , , % , , % , % , % , % , , % , , % , , % ,287 Agra Shadra LFG model xls 1/26/2010

16 TABLE B-1 PROJECTION OF LANDFILL GAS GENERATION AND RECOVERY UNDER MID-RANGE SCENARIO SHADRA LANDFILL, AGRA, INDIA MID-RANGE RECOVERY SCENARIO Disposal Refuse LFG Collection Predicted LFG Maximum Baseline** Methane Emissions Rate In-Place Generation System Recovery Power Plant LFG Flow Reduction Estimates** Year (Mg/yr) (Mg) (m 3 /hr) (cfm) (mmbtu/hr) Efficiency (%) (m 3 /hr) (cfm) (mmbtu/hr) Capacity* (kw) (m 3 /hr) CH4/yr) CO 2 eq/yr) , % , , % , , % , , % , , % , , % , , % , , % , , % , , % , , % , , % , , % , , % , % , % , % , % , % , % MODEL INPUT PARAMETERS: NOTES: Assumed Methane Content of LFG: 50% * Maximum power plant capacity assumes a gross heat rate of 10,800 Btus per kw-hr (hhv). Fast Decay Med. Decay Slow Decay Total Site Lo **Baseline LFG flow assumes no LFG recovery (no combustion). CERs do not include electricity Decay Rate Constant (k): generation, system down-time, or methane destruction efficiency assumptions. CH4 Generation Pot. (Lo) (ft3/ton): 1,851 4,790 4,712 1,567 Total estimated CERs for the period = 36,405 tonnes CO2e Metric Equivalent Lo (m3/mg): Agra Shadra LFG model xls 1/26/2010

17 TABLE B-2 PROJECTION OF LANDFILL GAS RECOVERY UNDER HIGH AND LOW RECOVERY SCENARIOS SHADRA LANDFILL, AGRA, INDIA HIGH RECOVERY SCENARIO LOW RECOVERY SCENARIO Collection Predicted LFG Maximum Baseline** Methane Emissions Collection Predicted LFG Maximum Baseline** Methane Emissions System Recovery Power Plant LFG Flow Reduction Estimates** System Recovery Power Plant LFG Flow Reduction Estimates** Year Efficiency (%) (m 3 /hr) (cfm) (mmbtu/hr) Capacity* (kw) (m 3 /hr) CH4/yr) CO 2 eq/yr) Efficiency (%) (m 3 /hr) (cfm) (mmbtu/hr) Capacity* (kw) (m 3 /hr) CH4/yr) CO 2 eq/yr) % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % ,294 35% , % ,038 35% , % ,001 35% , % ,145 35% , % ,436 35% , % ,848 35% , % ,359 35% , % ,953 35% , % ,613 35% , % ,329 35% , % ,090 35% , % ,889 35% , % ,718 35% , % ,573 35% Agra Shadra LFG model xls 1/26/2010

18 TABLE B-2 PROJECTION OF LANDFILL GAS RECOVERY UNDER HIGH AND LOW RECOVERY SCENARIOS SHADRA LANDFILL, AGRA, INDIA HIGH RECOVERY SCENARIO LOW RECOVERY SCENARIO Collection Predicted LFG Maximum Baseline** Methane Emissions Collection Predicted LFG Maximum Baseline** Methane Emissions System Recovery Power Plant LFG Flow Reduction Estimates** System Recovery Power Plant LFG Flow Reduction Estimates** Year Efficiency (%) (m 3 /hr) (cfm) (mmbtu/hr) Capacity* (kw) (m 3 /hr) CH4/yr) CO 2 eq/yr) Efficiency (%) (m 3 /hr) (cfm) (mmbtu/hr) Capacity* (kw) (m 3 /hr) CH4/yr) CO 2 eq/yr) % ,449 35% % ,342 35% % ,250 35% % ,170 35% % ,100 35% % ,038 35% % % % % % % % % NOTES: NOTES: * Maximum power plant capacity assumes a gross heat rate of 10,800 Btus per kw-hr (hhv). * Maximum power plant capacity assumes a gross heat rate of 10,800 Btus per kw-hr (hhv). **Baseline LFG flow assumes no LFG recovery (no combustion). CERs do not include electricity **Baseline LFG flow assumes no LFG recovery (no combustion). CERs do not include electricity generation, system down-time, or methane destruction efficiency assumptions. generation, system down-time, or methane destruction efficiency assumptions. Total estimated CERs for the period = 43,687 tonnes CO2e Total estimated CERs for the period = 25,484 tonnes CO2e Agra Shadra LFG model xls 1/26/2010

19 350 Figure B-1. LFG Generation and Recovery Projection Shadra Dump Site, Agra, India ,000 LFG Flow at 50% Methane (m3/hr) ,000 10,000 CERs CO2e) 5, LFG Generation Predicted recovery - Mid Range Predicted recovery - High range Predicted recovery - Low range 1/26/2010