Los_Reales_Landfill_Gas_Recovery_and_Reutilization_Feasibility_Assessment.pdf

Los Reales Landfill Landfill Gas Recovery and Reutilization Feasibility Assessment

City of Tucson

August 25, 2021

The Power of Commitment

The Power of Commitment

GHD

7560 N. La Cholla Boulevard, Tucson, Arizona 85741, United States T +1 520 623 9221 | F +1 520 623 3065 | E info-northamerica@ghd.com | ghd.com

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File name https://projects-northamerica.ghd.com/sites/uswest2/proptucsonlfgutiliza/ProjectDocs/11225318 - Los Reales Landfill Gas Recovery and Reutilization Assessment.docx

Author Nikhil Khurana, Bryan Szalda, Stephanie Stolz, Rippan Bhattacharjee, Jim Volk

Project manager Sarah Simmons

Client name City of Tucson

Project name Los Reales Landfill Gas Recovery and Reutilization Assessment

Document title Los Reales Landfill | Landfill Gas Recovery and Reutilization Feasibility Assessment

Revision version Rev A

Project number 11225318

Document status

Status Code

Revision Author Reviewer Approved for issue

Name Signature Name Signature Date

A N Khurana S Simmons M Plaschke

© GHD 2021

This document is and shall remain the property of GHD. The document may only be used for the purpose for which it was commissioned and in accordance with the Terms of Engagement for the commission. Unauthorized use of this document in any form whatsoever is prohibited.

http://www.ghd.com/

The Power of Commitment i

Executive summary

Note to COT in Draft Report: Exec Summary will be included in Final Report

The Power of Commitment ii

Contents

1. Introduction 1

1.1 Context 1

1.2 Purpose of this report 1

1.3 Glossary 1

1.4 Assumptions and Limitations 3

2. Framing the Opportunity and Constraints 4

2.1 Overview 4

2.2 Problem/Opportunity Statements 5

3. Landfill Context 6

3.1 Landfill History and Current Status 6

3.2 Existing Assets 6

3.3 Regional Pipeline and Power Infrastructure 9

3.4 LFG Utilization Investigations to Date 11

4. Landfill Gas Analysis 11

4.1 Overview 11

4.2 Basics of LFG Generation 11

4.3 Historical Waste Composition and Volumes 12

4.4 Projections of LFG Generation Potential 13

4.5 LFG Generation Results 14

4.6 Existing Collection System Review 16

4.7 Collection System Upgrade Options 18

4.8 Outcomes and Considerations 20

5. Detailed LFG Utilization Alternatives 21

5.1 Summary 21

5.2 Description of Alternatives 23

5.3 Evaluation Approach and Assumptions 33

5.4 Alternatives Evaluation Results 35

6. Triple Bottom Line Analysis 38

6.1 Overview and Approach 38

6.2 Evaluation Assumptions 39

6.3 Evaluation Results 40

7. Recommended Alternative 42

8. Macro Fleet Assessment and High-Level Transition Plan 43

8.1 Objectives 43

8.2 Context and Technology Review 44

8.3 Summary Findings 45

8.4 Implications for LFG Reutilization 49

The Power of Commitment iii

9. Procurement Ownership Model Analysis 50

9.1 Overview 50

9.2 Key Principles 50

9.3 Approach 51

9.4 Review of Historical Contracts 51

9.5 Common Procurement Ownership Models 52

9.6 Procurement Ownership Model Analysis 56

9.7 Analysis and Recommendations 57

10. Next Steps 58

Table Index Table 1 Assessment Glossary 1 Table 2 Population Growth Scenarios 13 Table 3 Organics Diversion Scenarios 14 Table 4 LFG Generation Estimates – Low, Middle and Upper Range 15 Table 5 Landfill Gas Well Operating Status and March 2021 Wellfield Data 16 Table 6 GCCS Upgrade Options 18 Table 7 Upgrade Cost Estimates for GCCS Moderate Collection Option 19 Table 8 Upgrade Cost Estimates for GCCS High Collection Option 20 Table 9 Summary of LFG Reutilization Detailed Alternatives 22 Table 10 Summary of GCCS Upgrade Infrastructure Options 22 Table 11 Estimated RNG Production - Alternatives A1, A2, and A3 24 Table 12 CAPEX Estimates – Alternatives A1, A2, and A3 24 Table 13 OPEX Estimates – Alternatives A1, A2, and A3 24 Table 14 Estimated CNG Production – Alternatives B1 and B2 27 Table 15 CAPEX – Alternative B2 27 Table 16 OPEX – Alternative B2 28 Table 17 CAPEX – Alternative B1 28 Table 18 OPEX – Alternative B1 28 Table 19 On-site Power Generation Production – Alternative C 31 Table 20 CAPEX Estimates – Alternative C 31 Table 21 OPEX Estimates – Alternative C 32 Table 22 Summary of Assumptions for Alternative Evaluation 34 Table 23 RIN price required to achieve NPV under Scenario A2 (RNG + RIN) 37 Table 24 Electricity feed-in tariff required to achieve NPV under Scenario C (onsite electricity) 37 Table 25 Triple Bottom Line Metric Valuation Assumptions 40 Table 26 Estimate of Triple Bottom Line NPV by Alternative with Breakdown 40 Table 27 Summary of current COT fleet assets 45 Table 28 Financial Analysis Summary 47 Table 29 Environmental Analysis Summary 49 Table 30 Typical Procurement Models 52 Table 31 Review of Ameresco Proposals – Commercial Structures and Assumptions 53

The Power of Commitment iv

Figure Index Figure 1 Pipeline Route – Decommissioned Los Reales Landfill to TEP LFG Pipeline 8 Figure 2 Existing Natural Gas and Power Infrastructure in Vicinity of the Landfill 10 Figure 3 Estimated Los Reales Landfill Waste Composition 13 Figure 4 LFG Generation Estimates for All Waste Diversion AND Population Growth

Scenarios 15 Figure 5 Plan View of Los Reales Landfill 17 Figure 6 Potential Improved Landfill Gas Collection Rates 18 Figure 7 Shortlisted Alternatives for Detailed Evaluation 21 Figure 8 RNG Production Process – Alternatives A1, A2, and A3 23 Figure 9 CNG production flow 27 Figure 10 On-Site Power Production Flow 31 Figure 11 Net Present Value (NPV) for the utilization scenarios 36 Figure 12 Discounted Payback Period for the utilization scenarios 36 Figure 13 Overall Project Evaluation – 2400 scfm RNG Injection with sale to AZ Transport

Customer (Alt A3) 41 Figure 14 Factors affecting a transition to 100% ZEV Fleet 45 Figure 15 Demand for vehicle charging electricity (MWh per year) under different transition scenarios Vehicle Charging Electricity Under Different Transition Scenarios 47 Figure 16 Demand for CNG Vehicle Fuel (GGEs per year) Under Different Transition

Scenarios 48 Figure 17 COT CNG Demand for Fleet Transition Scenarios vs. Supply from LFG Reutilization 50 Figure 18 Overview of the RIN Transaction System and Key Market Participants. 55

Appendices Appendix A LandGEM Modeling and Supporting Landfill Gas Analysis Calculations Appendix B GHD Atlas Tool Well Field Data Appendix C GCCS Upgrade Costs Appendix D Macro Fleet Assessment Supporting Documentation Appendix E Technoeconomic Model Assumptions Appendix F Triple Bottom Line Model Assumptions Appendix G Landfill Gas Utilization Options

GHD | City of Tucson | 11225318 | Los Reales Landfill 1 This document is in draft form. The contents, including any opinions, conclusions or recommendations contained in, or which may be implied from, this draft document must not be relied upon. GHD reserves the right, at any time, without notice, to modify or retract any part or all of the draft document. To the maximum extent permitted by law, GHD disclaims any responsibility or liability arising from or in connection with this draft document.

1. Introduction

1.1 Context

The Los Reales Landfill (the “Landfill”) is an active regional landfill operated by the City of Tucson (COT) which serves the residents and businesses of Tucson and Pima County.

Landfill gas (LFG) is a natural byproduct of the decomposition of organic material in the Landfill, and due to its energy content is commonly used as an energy source in industrial applications. In 1998, a Gas Collection and Control System (GCCS) was installed at the site and subsequently, LFG was transported by dedicated pipeline to the Tucson Electric Power (TEP) H. Wilson Sundt Generation Station (previously called Irvington Station). The LFG was used as supplementary fuel for the Unit No. 4 boiler, which produces electricity from steam generation.

In 2019, the contract to supply LFG to TEP was not renewed and instead, collected LFG is combusted through the onsite blower/flare station. The Landfill is expected to continue producing LFG for the near to medium-term, and as such finding a way to maximize the value of the biogas resource without compromising overarching climate change aspirations is a priority for COT.

1.2 Purpose of this report

The goal of this Landfill Gas Recovery and Reutilization Feasibility Assessment (Assessment) is to provide:

– An updated assessment of LFG production capacity (with specific consideration to COT’s new waste diversion goals), status of the existing GCCS, and recommended upgrades to maximize capture efficiency.

– A stock-take of COT’s transit fleet to understand existing and future fuel demands as COT transitions its fleet to renewable and electric fuel sources.

– Assessment of the existing CNG fueling facilities to confirm operational capacity and potential expansion/upgrade opportunities to meet future demand.

– Development of a transition plan that optimizes the introduction of new electric vehicles with the operation of the current CNG powered fleet.

– Analysis of LFG re-use options on their economic performance, environment impact, and alignment to COT’s carbon neutrality and waste diversion goals.

– Identification of ownership models which will minimize risk in procurement and delivery for COT while ensuring sufficient interest and innovation from the private sector market to maximize potential benefits.

1.3 Glossary

Table 1 Assessment Glossary

Acronym Definition

ACC Arizona Corporation Commission

BEB Battery Electric Buses

Los Reales Landfill Quick Facts

159 Acres Proposed Growth

1,087 Acres Total

89 Acres Lined and 175 Acres

Accepts municipal solid waste, construction & demolition waste

Opened

GHD | City of Tucson | 11225318 | Los Reales Landfill 2 This document is in draft form. The contents, including any opinions, conclusions or recommendations contained in, or which may be implied from, this draft document must not be relied upon. GHD reserves the right, at any time, without notice, to modify or retract any part or all of the draft document. To the maximum extent permitted by law, GHD disclaims any responsibility or liability arising from or in connection with this draft document.

Acronym Definition

BEV Battery Electric Vehicles

BTU British Thermal Unit

CAPEX Capital Expenditure

CI carbon intensity

CNG Compressed Natural Gas

CO2 carbon dioxide

COBRA Co-benefits Risk Assessment

Cornerstone Cornerstone Environmental Group

COT City of Tucson

DGE diesel gasoline equivalent

EEC Environmental Engineer Consultants

EPNG El Paso Natural Gas

GCCS Gas Collection and Control System

GGE gasoline gallon equivalent

HDPE high-density polyethylene

HFCB Hydrogen Fuel Cell Buses

IRR Internal Rate of Return kg kilogram

KM Kinder Morgan kW kilowatt kWh kilowatt hours

LandGEM Landfill Gas Emissions Model

LCFS Low Carbon Fuel Standard

LFG Landfill Gas

LFGTE landfill gas-to-energy

MSW municipal solid waste

MW megawatt

N2 nitrogen

NPV Net Present Value

O2 oxygen

O&M Operations and Maintenance

OPEX Operational Expenditure

PSA pressure swing absorption psig pounds per square inch gage

RINs Renewable Identification Numbers

GHD | City of Tucson | 11225318 | Los Reales Landfill 3 This document is in draft form. The contents, including any opinions, conclusions or recommendations contained in, or which may be implied from, this draft document must not be relied upon. GHD reserves the right, at any time, without notice, to modify or retract any part or all of the draft document. To the maximum extent permitted by law, GHD disclaims any responsibility or liability arising from or in connection with this draft document.

Acronym Definition

RNG Renewable Natural Gas RTO regenerative thermal oxidizer scfm standard cubic feet per minute SWG Southwest Gas TOPSC Thomas O. Price Service Center TEM Technoeconomic Model TEP Tucson Electric Power U.S. United States USEPA United States Environmental Protection Agency WACC weighted average cost of capital ZAPCO Zahren Alternative Power Corporation ZEV zero emission vehicles

1.4 Assumptions and Limitations

This report has been prepared by GHD for COT and may only be used and relied on by COT for the purpose agreed between GHD and COT as set out in Section 1.2 of this report.

GHD otherwise disclaims responsibility to any person other than the COT arising in connection with this report. GHD also excludes implied warranties and conditions, to the extent legally permissible.

The services undertaken by GHD in connection with preparing this report were limited to those specifically detailed in the report and are subject to the scope limitations set out in the report.

The opinions, conclusions and any recommendations in this report are based on conditions encountered and information reviewed at the date of preparation of the report. GHD has no responsibility or obligation to update this report to account for events or changes occurring subsequent to the date that the report was prepared.

The opinions, conclusions and any recommendations in this report are based on assumptions made by GHD described in this report. GHD disclaims liability arising from any of the assumptions being incorrect.

GHD has prepared the preliminary cost estimates set out in Sections 5 through 8 of this report (“Cost Estimate”) using information reasonably available to the GHD employee(s) who prepared this report; and based on assumptions and judgments made by GHD

The Cost Estimate has been prepared for the purpose stated in Section 1.2 and must not be used for any other purpose.

The Cost Estimate is a preliminary estimate only. Actual prices, costs and other variables may be different to those used to prepare the Cost Estimate and may change. Unless as otherwise specified in this report, no detailed quotation has been obtained for actions identified in this report. GHD does not represent, warrant or guarantee that the project can or will be undertaken at a cost which is the same or less than the Cost Estimate.

Where estimates of potential costs are provided with an indicated level of confidence, notwithstanding the conservatism of the level of confidence selected as the planning level, there remains a chance that the cost will be greater than the planning estimate, and any funding would not be adequate. The confidence level considered to be most appropriate for planning purposes will vary depending on the conservatism of the user and the nature of the project. The user should therefore select appropriate confidence levels to suit their particular risk profile.

GHD | City of Tucson | 11225318 | Los Reales Landfill 4 This document is in draft form. The contents, including any opinions, conclusions or recommendations contained in, or which may be implied from, this draft document must not be relied upon. GHD reserves the right, at any time, without notice, to modify or retract any part or all of the draft document. To the maximum extent permitted by law, GHD disclaims any responsibility or liability arising from or in connection with this draft document.

GHD has prepared this report on the basis of information provided by COT and others who provided information to GHD (including Government authorities), which GHD has not independently verified or checked beyond the agreed scope of work. GHD does not accept liability in connection with such unverified information, including errors and omissions in the report which were caused by errors or omissions in that information.

2. Framing the Opportunity and Constraints

2.1 Overview

COT has a number of strategic drivers and objectives that will influence its selection of preferred option for reutilization of LFG from the Landfill.

Broadly, COT has committed to improve its overall environmental impact and reduce its contribution to climate change, notably with Resolution No. 23222, which was adopted by Mayor and Council in 2020. The Resolution calls for COT to investigate and make significant changes to advance its sustainability goals and improve its resiliency to climate change impacts. This resolution follows a series of recent actions to advance climate action and fulfill COT's ambitions to act as a global leader in effort to combat climate change.

Specific initiatives which COT has identified for further development, but are not fully defined at the time of this Assessment are:

The status and implications of these initiatives are discussed briefly in the subsections below. In general, GHD has conducted this Assessment with a view to create a recommendation that is:

– Consistent with COT’s climate and sustainability visions and plans.

– Robust to the potential range of outcomes that may occur as COT further defines and commits to its climate and sustainability initiatives.

2.1.1 Zero Waste Diversion

Resolution No. 23222 recommended development of a Zero Waste Plan with a 50 percent waste diversion goal by 2030 and zero waste (to the Landfill) by 2050. The Zero Waste Plan will define how COT intends to achieve these goals and divert waste from Landfill. The development of the Zero Waste Plan is planned to commence in 2021 and is not available at the time of this Assessment.

Zero Waste initiatives impact LFG reutilization since waste diversion initiatives will change the quantities and types of materials sent to the Landfill, and therefore, there is some uncertainty regarding LFG quality and quantity over time.

To manage this in this Assessment, several scenarios were developed to estimate Landfill volumes and Landfill gas generation potential over time, including scenarios ranging from no additional waste diversion to a scenario where the Zero Waste Plan is fully achieved (see Section 4).

The detailed alternatives evaluated in this Assessment are designed and sized such that they are compatible and feasible for all the waste diversion scenarios.

Carbon Neutrality Goals Zero Waste Diversion Plan

Fleet Electrification Transition

GHD | City of Tucson | 11225318 | Los Reales Landfill 5 This document is in draft form. The contents, including any opinions, conclusions or recommendations contained in, or which may be implied from, this draft document must not be relied upon. GHD reserves the right, at any time, without notice, to modify or retract any part or all of the draft document. To the maximum extent permitted by law, GHD disclaims any responsibility or liability arising from or in connection with this draft document.

2.1.2 Fleet Electrification Transition

Resolution No. 23222 calls for COT to ‘phase-out from fossil fuels to electrification of COT’s transit and vehicle fleet in the long-term’. In addition, Mayor and Council Memorandum FY 19-20 identified green transportation and mobility as a focus area, with a goal to transition the Sun Tran bus fleet to electric.

COT’s Electric Vehicle Readiness Roadmap (2021) identifies pursuing electrification of COT’s light duty fleet as an action to be prioritized in 2021 and electrification of transit fleet as a short-term goal. It identifies the need to conduct a full review of the entire COT fleet and develop a fleet transition plan along with energy sourcing and electric vehicle infrastructure needs.

In line with the targets set by COT’s adopted resolution, this assessment includes:

– Review of COT’s existing compressed natural gas (CNG) Facility to determine best use of that existing asset.

– Development of a macro-level fleet review indicating the current state of fleet operations.

– Development of high-level fleet transition scenarios. These have been generated to cover a wide range of potential electrification pathways.

– Development of an indicative, high-level fleet electrification timeline.

COT’s decision on its fleet electrification plan and timeline is a major decision as it has substantial implications on COT’s operations, funding, and climate action outcomes. It also has broader implications and interfaces with the community (e.g., transit passengers) and other agencies (such as power provider, TEP).

The preferred LFG reutilization approach has been tested against various fleet electrification scenarios and influences. Elements of this Assessment also provide initial analysis and data that will help inform the COT as it continues to finalize its fleet transition plan.

2.1.3 Carbon Neutrality Goals

Resolution No. 23222 also calls for COT to ‘reduce emissions as quickly as possible to achieve carbon neutrality by 2030’. Specifically, 100 percent of COT’s light-duty vehicles and 90 percent of all transit and school buses need to be electrified by 2030.

Liquefied Natural Gas reutilization options, which minimize energy demand, reduce fugitive methane emissions, or increase renewable energy generation can contribute to this goal. To this end, a societal cost of carbon has been included in the technoeconomic analysis (see Section 5).

2.2 Problem/Opportunity Statements

COT’s strategic and climate action initiatives collectively influence the selection, sizing, or configuration of the preferred reutilization. To ensure clarity on the fundamental reasons for considering an LFG reutilization project, GHD and COT staff have collaboratively determined and distilled the core drivers into the following two ‘problem/opportunity statements’. These statements are articulations of why action needs to be considered at this time.

The current recovery and reutilization practices for LFG do not proactively contribute to COT’s carbon neutrality and other long-term environmental and sustainability goals.

Statement 1

The current recovery and reutilization practices for LFG do not leverage new technology or market trends, and therefore, do not capitalize on opportunities to reduce costs or increase revenue for COT.

Statement 2

GHD | City of Tucson | 11225318 | Los Reales Landfill 6 This document is in draft form. The contents, including any opinions, conclusions or recommendations contained in, or which may be implied from, this draft document must not be relied upon. GHD reserves the right, at any time, without notice, to modify or retract any part or all of the draft document. To the maximum extent permitted by law, GHD disclaims any responsibility or liability arising from or in connection with this draft document.

Keeping these statements in mind as underlying drivers for future investment in the Landfill, an effective and efficient solution for LFG reuse should:

– Contribute and be compatible with COT’s long term sustainability goals

– Be competitive within the changing commercial energy landscape.

– Acknowledge the operational realities of the Landfill.

3. Landfill Context

3.1 Landfill History and Current Status

The Landfill began accepting municipal solid waste (MSW), construction, and demolition waste in 1967.

In November 1997, COT contracted with Zahren Alternative Power Corporation (ZAPCO) (now US Energy Biomass Corporation) to collect, process, and sell LFG from the Landfill. A comprehensive GCCS was constructed in 1998 by ZAPCO, as part of the development of a medium British Thermal Unit (BTU) gas to energy project. The system started operating in May 1998 with collected LFG being flared at the blower/flare station. In August 1999, the construction of an LFG compressor station and a transmission pipeline was completed. LFG was transported by this new dedicated pipeline to the TEP H. Wilson Sundt Generation Station. The LFG was used as supplementary fuel for the Unit No. 4 boiler.

The arrangement between COT, ZAPCO, and TEP ceased in 2019 and LFG is no longer sent to the TEP H. Wilson Sundt Generation Station. The termination of this arrangement occurred due to several factors, which are presented in Appendix G. The pipeline between the Landfill and TEP H. Wilson Sundt Generation Station was decommissioned in-place in 2019.

Currently, all LFG collected by the GCCS is flared at the Landfill. COT currently operates the Landfill and GCCS infrastructure.

Further information on the GCCS, LFG cleanup and transfer pipeline infrastructure is provided in subsections below.

3.2 Existing Assets

3.2.1 Gas Extraction Wells

The existing GCCS currently includes 119 LFG vertical extraction wells, of which 33 are active. The wells are connected via a network of high-density polyethylene (HDPE) lateral and header piping, to the LFG compressor and candlestick flare systems (described below). Because of the moisture content of the extracted LFG, drip traps and sumps are installed to remove condensation from the piping system at discrete locations. The current extraction system does not include any horizontal collectors or slip wells.

In 2020, an average of 896 standard cubic feet per minute (scfm) of Landfill gas was collected from the active gas extraction wells and routed to the open flare for destruction.

Section 4 and Appendix B provide further detail on the operational characteristics and performance of the LFG extraction wells and areas to improve the quantity and quality of LFG capture.

3.2.2 Other GCCS Infrastructure

A comprehensive GCCS, consisting of an extraction wellfield and a blower/ flare station, was constructed in 1998 by ZAPCO, as part of the development of a medium-BTU gas-to-energy project utilizing collected LFG from the Landfill.

The system became operational in May 1998 with collected LFG flared at the blower/flare station. In August 1999, the

GHD | City of Tucson | 11225318 | Los Reales Landfill 7 This document is in draft form. The contents, including any opinions, conclusions or recommendations contained in, or which may be implied from, this draft document must not be relied upon. GHD reserves the right, at any time, without notice, to modify or retract any part or all of the draft document. To the maximum extent permitted by law, GHD disclaims any responsibility or liability arising from or in connection with this draft document.

construction of an LFG compressor station adjacent to the blower/flare station, and a 3.5-mile LFG transmission pipeline was completed by ZAPCO. Up until November 2019, the LFG collected from the Landfill wellfield was cooled, dried, and condensed at the compressor station and transported via underground pipeline to TEP H. Wilson Sundt Generation Station. The LFG was used as supplementary fuel for burners which heated the TEP Unit #4 boiler, providing steam to turn turbines for electrical power generation. For this process, the blower/flare station was bypassed and was only used during periods of time when the compressor and/or TEP H. Wilson Sundt Generating Station Unit #4 were not operating due to maintenance or repair. Since cessation of the contract with TEP in 2019, collected LFG has been transmitted to the blower/flare station continuously where it is combusted in a utility flare.

The collected LFG is currently routed from the vertical extraction wells via laterals and a perimeter header line to the elevated candlestick flare at the blower/flare station by two blowers (Lamson model 850-0-1-2-GD, 40 horsepower, 1,345 scfm each). Through adjustments to the valving configurations, either of these blowers (or both) may operate and send the collected LFG to the candlestick flare.

The flare system installed at the Landfill is a candlestick flare manufactured by John Zink, model ZEF 1030, incorporating the following features:

– Ten-inch diameter by 30-foot-high elevated candlestick flare constructed of A-36 carbon steel. The flare is designed to operate under a maximum wind loading of 100 miles per hour.

– Propane supply with a spark plug igniter for flame ignition.

– Thermocouple for primary and pilot flame confirmation.

– Blower/flare station controller panel.

– Flow meter (totalizer) and flame arrestor.

– Maximum capacity of 2,690 scfm

3.2.3 Landfill to TEP Pipeline

In 1998, ZAPCO completed construction of the LFG transmission pipeline between the Landfill and the TEP H. Wilson Sundt Generation Station, located at the southeast corner of Alvernon Way and Irvington Road. The pipeline route is shown in Figure 1 below. The pipeline crosses I-10, Union Pacific railway line, and Valencia Road/Benson Highway.

GHD | City of Tucson | 11225318 | Los Reales Landfill 8 This document is in draft form. The contents, including any opinions, conclusions or recommendations contained in, or which may be implied from, this draft document must not be relied upon. GHD reserves the right, at any time, without notice, to modify or retract any part or all of the draft document. To the maximum extent permitted by law, GHD disclaims any responsibility or liability arising from or in connection with this draft document.

Source: Construction Documentation Report, SCS Engineers, September 1999. Blue shading added by GHD.

Figure 1 Pipeline Route – Decommissioned Los Reales Landfill to TEP LFG Pipeline

The total length of the LFG transmission pipeline is approximately 19,200 feet (approximately 3.6 miles) and is designed to convey LFG at a maximum flow rate of approximately 3,000 scfm, under normal operation pressure of about 19 pounds per square inch gage (psig). The pipeline consists of 14-inch diameter SDR 21 HDPE pipe, encased in a 20-inch diameter schedule 20 steel casing at each jack and bore interval location. The pipeline operated between 1999 and 2018.

As it is understood, the pipeline is owned by Biogas Energy Solutions, Inc., the parent company of ZAPCO. The Operations and Maintenance (O&M) contractor utilized during operation was Environmental Engineer Consultants

(EEC).

After the arrangement to send LFG to TEP was terminated, the pipeline was decommissioned in-place in 2019.

According to TEP, the pipeline was laid up with nitrogen (N2), capped with concrete. Change of custody was managed by EEC with TEP acting as middleman between EEC and Biogas (owner) during the pipeline decommissioning.

There are conflicting views on the condition and reusability of this pipeline. GHD understands that:

– TEP believes the pipeline is in decent condition and is usable.

– COT believes the pipeline is in poor condition and could not be reused without significant rehabilitation or replacement.

Neither COT nor TEP have any documentation to confirm pipeline status. GHD received O&M and construction documentation binders from EEC in June 2021. GHD could not find documentation related to the pipeline decommission.

In light of the uncertainty as to the condition of the Landfill to TEP pipeline, GHD has not proposed alternatives that involve recommissioning and reusing the Landfill to TEP pipeline. This stance is viewed as reasonable in light of other factors:

GHD | City of Tucson | 11225318 | Los Reales Landfill 9 This document is in draft form. The contents, including any opinions, conclusions or recommendations contained in, or which may be implied from, this draft document must not be relied upon. GHD reserves the right, at any time, without notice, to modify or retract any part or all of the draft document. To the maximum extent permitted by law, GHD disclaims any responsibility or liability arising from or in connection with this draft document.

– As discussed in Appendix G and based on feedback from TEP on the historic arrangement, there does not appear to be justification to reuse the pipeline to send raw or processed LFG to the TEP H. Wilson Sundt Generation Station.

– Reuse of the pipeline to transfer processed gas (e.g., RNG) for pipeline injection near the TEP H. Wilson Sundt Generation Station could be considered. However, there are viable RNG injection points close (within 2 miles) to the Landfill which would entail considerably less reuse risk.

Further information on the condition of the pipeline would be useful to validate the judgements made in this analysis.

3.3 Regional Pipeline and Power Infrastructure

The availability and capacity of the following infrastructure types can influence the preferred LFG reutilization option by constraining and/or influencing the costs of certain options:

– Natural gas pipelines (for injection)

– Power supply

3.3.1 Natural Gas Pipelines

There are several existing natural gas transmission pipelines in the vicinity of the Landfill to which RNG produced from LFG could be injected, as shown on Figure 2. These transmission pipelines are now owned and operated Kinder Morgan (KM). Prior to 2012 they were owned and operated by El Paso Natural Gas (EPNG).

Southwest Gas (SWG) operates the local natural gas distribution network. These smaller diameter pipes are not typically used for RNG injection but could be considered.

KM provided guidance and advice to GHD regarding their distribution pipelines, in particular:

– KM Line 1103 is a 30-inch line which provides gas east-to-west from the Permian Basin and connects directly to California distribution networks. The line has capacity to accept additional injection. Its operating pressure is approximately 800 psig, with a maximum operating pressure of 809 psig. The Landfill is approximately 1.6 miles north. KM Line 1103 is the preferred line for RNG injection.

– KM Line 1007 is located approximately 2 miles north of the Landfill. It is northwest of I-10 and links directly to El Paso and California. It is not the primary east-west distribution main and has less capacity than KM Line 1103.

– KM Line 2110, running north-south and located approximately 1 mile west of the Landfill, is the ‘western connector’. This line is used to serve local Tucson demand. It is a 10-inch line and has an operating pressure of 650 psig. Line 2110 has less capacity than Lines 1103 and 1007 and has limited capacity for injection.

The Landfill is advantageously located in the context of existing natural gas transmission infrastructure. The preferred injection pipeline, KM Line 1103, is located only 1.6 miles from the Landfill, meaning that a relatively short transfer pipeline between the Landfill and injection point would be required for RNG injection.

GHD | City of Tucson | 11225318 | Los Reales Landfill 10 This document is in draft form. The contents, including any opinions, conclusions or recommendations contained in, or which may be implied from, this draft document must not be relied upon. GHD reserves the right, at any time, without notice, to modify or retract any part or all of the draft document. To the maximum extent permitted by law, GHD disclaims any responsibility or liability arising from or in connection with this draft document.

Figure 2 Existing Natural Gas and Power Infrastructure in Vicinity of the Landfill

3.3.2 Power Supply Infrastructure

TEP provided high-level guidance related to the existing power infrastructure in the vicinity of the Landfill. In the context of COT potentially generating power and selling back to the grid, the advice was as follows:

– The Landfill is located within TEP’s major ‘load pocket’ so there are no obvious constraints to having large scale (e.g., 8 megawatts [MW]) power feed into the grid in that area. A steady baseload generation in that area would be easier for the grid to handle.

GHD | City of Tucson | 11225318 | Los Reales Landfill 11 This document is in draft form. The contents, including any opinions, conclusions or recommendations contained in, or which may be implied from, this draft document must not be relied upon. GHD reserves the right, at any time, without notice, to modify or retract any part or all of the draft document. To the maximum extent permitted by law, GHD disclaims any responsibility or liability arising from or in connection with this draft document.

– If the interconnect is complex, TEP can take approximately 2 to 4 years to arrange the interconnect, which will work tangential to the environmental approvals process. With a simpler interconnect, which this tentatively appears to be, it would be in the matter of months to arrange.

3.4 LFG Utilization Investigations to Date

In recent years, COT has pursued several investigations and discussions on potential uses for the LFG from the Landfill. GHD has leveraged this background information in this analysis. A brief overview of the most relevant includes:

– In 2015, Cornerstone Environmental Group (Cornerstone) provided assessment of the existing GCCS and upgrade options to maximize utilization of the LFG. The evaluation included assessment of medium-BTU fuel delivery, power production (IC engines or turbines), and onsite renewable CNG production. In terms of financial return, the study preferred the continued sale of medium-BTU to TEP (albeit directly instead of through a third party), followed by the generation and sale of CNG. It did note that the options were not exclusive of each other, and combinations of options could be implemented.

– In 2016, United States (U.S.) Energy completed a high-level economic evaluation into LFG upgrading to CNG for injection into a commercial network (SWG or EPNG) as opposed to dispensing at the Thomas O. Price Service Center (TOPSC) CNG fueling facility (as in the Cornerstone report). The report argued that this would reduce capital cost and provide access to a larger customer base. This report similarly concluded that upgrading LFG to CNG would provide a financially attractive option with a relatively fast payback period (2 to 4 years under a conservative scenario).

– In 2019 and 2020, COT received several proposals for LFG upgrading and pipeline injection. These proposals emphasized the value of attributes (D3, D5 Renewable Identification Numbers [RINS], Low Carbon Fuel Standard [LCFS] credits) as a major factor in maximizing the value of the biogas resource.

This Assessment has reviewed and incorporated relevant findings from these earlier investigations and is intended to supersede these earlier efforts and provide a pathway for COT to move forward.

4. Landfill Gas Analysis

4.1 Overview

This section includes:

– Brief discussion of factors that influence LFG production within landfills.

– Review of Landfill historical waste composition and volumes.

– Explanation of and results from GHD’s modeling to project future potential LFG generation for different population growth and waste diversion scenarios.

– Review of Landfill GCCS infrastructure and well performance in capturing LFG.

– Discussion of required upgrades to the GCCS to capture more gas, including approach, cost estimates and timelines.

4.2 Basics of LFG Generation

MSW landfills such as the Los Reales Landfill produce LFG from the organic decomposition of waste under anaerobic conditions (oxygen [O2]-free environment). The amount or rate of LFG generation from a landfill is based on the following factors:

GHD | City of Tucson | 11225318 | Los Reales Landfill 12 This document is in draft form. The contents, including any opinions, conclusions or recommendations contained in, or which may be implied from, this draft document must not be relied upon. GHD reserves the right, at any time, without notice, to modify or retract any part or all of the draft document. To the maximum extent permitted by law, GHD disclaims any responsibility or liability arising from or in connection with this draft document.

– Waste composition: A landfill that contains a large amount of organic waste (or putrescible waste) will generate more LFG production. Non-putrescible wastes such as ash, concrete, and soils do not contribute to LFG production within a landfill.

– Waste quantity: the total quantity of waste produced by the population and its final destination, whether landfill or other, has a direct influence on LFG production. Waste diversion initiatives and population growth are key factors that drive total waste quantity.

– Age of Refuse: Waste that is more recently buried (2 to 5 years old) will generate more LFG than older waste that has been buried for greater period of time (i.e., greater than 10 to 20 years).

– Presence of O2: Methanogenesis (the production of methane by methanogens) will be inhibited with the presence of O2 within a landfill because aerobic bacteria are generally more dominant than anaerobic bacteria.

– Moisture content: High moisture within a landfill encourages LFG production. Practices such as recirculation (the recycling of leachate back into a landfill) will increase LFG production.

– Temperature: As temperature within a landfill rises, bacterial activity rises, resulting in increased LFG production.

Landfills typically produce more LFG in the summer months than in the winter months.

4.3 Historical Waste Composition and Volumes

Details on the Landfill open year, closure year, design capacity and historical annual waste acceptance rates (for 1967 through 2020) were based on information provided by COT. COT also provided annual averages of LFG collection rates (in scfm) for the period of 2010 through 2020.

The total annual waste acceptance values provided by COT were broken down into waste types using data provided in a study conducted by Cascadia (City of Tucson Waste Diversion Plan and Roadmap, January 15, 2014). Historical waste acceptance at the Landfill was broken down into the following categories, with full detail on volumes provided in Appendix A, Table A.1:

– Bulk waste

– Paper waste

– Food waste

– Garden waste

– Wood waste

– Textile waste

– Construction and demolition waste

– Inert (non-putrescible) waste

GHD | City of Tucson | 11225318 | Los Reales Landfill 13 This document is in draft form. The contents, including any opinions, conclusions or recommendations contained in, or which may be implied from, this draft document must not be relied upon. GHD reserves the right, at any time, without notice, to modify or retract any part or all of the draft document. To the maximum extent permitted by law, GHD disclaims any responsibility or liability arising from or in connection with this draft document.

Figure 3 Estimated Los Reales Landfill Waste Composition

Appendix A, Table A.2 provides a summary of the estimated waste-in-place at the Landfill for the period of 1967 through 2020.

4.4 Projections of LFG Generation Potential

4.4.1 Quantity and Composition

The two key drivers of waste quantity are population growth and waste diversion initiatives. As discussed in Section 2.1.1, COT is developing a plan to improve waste diversion, with a goal of zero waste to Landfill by 2050.

Population growth also has inherent uncertainty, exacerbated by the impact of the COVID-19 pandemic and the substantial changes to the way people live, work, and migrate. To account for these, GHD developed several scenarios, shown in Table 2 and Table 3.

The population growth scenarios were developed by GHD and feedback from COT’s planning division was incorporated. The waste diversion scenarios were based on GHD’s extensive work with municipalities across North America and are reasonable ‘templates’ of waste diversion that are being achieved elsewhere. A key consideration is that ‘zero’ waste is usually achieved when diversion rates of approximately 90 percent are achieved (i.e., not 100 percent).

Waste diversion initiatives are assumed to apply to food waste, paper waste, and yard waste categories. All other waste categories are not impacted and continue to be sent to the Landfill.

Table 2 Population Growth Scenarios

Scenario Annual Rate of Growth

Low Growth 0.5%

Average Growth 1.1%

High Growth 1.5%

Population growth rates shown assumed to begin in 2021 and end in 2050. After 2050, no growth or decline in population is assumed.

Further information on assumptions underlying population growth rates is included in Appendix A Section 2

GHD | City of Tucson | 11225318 | Los Reales Landfill 14 This document is in draft form. The contents, including any opinions, conclusions or recommendations contained in, or which may be implied from, this draft document must not be relied upon. GHD reserves the right, at any time, without notice, to modify or retract any part or all of the draft document. To the maximum extent permitted by law, GHD disclaims any responsibility or liability arising from or in connection with this draft document.

A further discussion of the reasoning behind the population growth assumptions is provided in Appendix A. The model also accounts for variation in the diversion of organics from the waste stream. Table 3 below summarizes the assumptions used to define the different scenarios of organics diversion:

Table 3 Organics Diversion Scenarios

Scenario Organics Diversion Rate

Baseline No additional diversion

Medium Diversion 30% diversion by 2030 75% diversion by 2050

High Diversion 50% diversion by 2030 90% diversion by 2050

These diversion rates apply to food waste, paper waste and yard waste. All other waste categories are not impacted and continue to be sent to the Landfill.

Assumed linear changes in diversion rate to meet the milestones cited in this table.

Combining the population growth and organics diversion scenarios, a set of nine total LFG generation scenarios were produced.

4.4.2 Age, Oxygen, Temperature, and Other Factors

The U.S. Environmental Protection Agency (USEPA) Landfill Gas Emissions Model (LandGEM) was used for estimating LFG generation from the Landfill. This model accounts for these factors. Details on the assumptions and outputs from this model are included in Appendix A (Section 1, tables A.3 through A.8, and LandGEM Model Summary Reports).

4.5 LFG Generation Results

Figure 4 below shows the predicted LFG generation estimates for each of the nine scenarios. The curves represent the total theoretical production of LFG at the Landfill in each year.

The curves range from the lower bound scenario of low-population growth and high organics diversion to the upper bound scenario of high population growth and no additional organics diversion. Figure 4 also shows the actual LFG collected at the Landfill on an average annual basis for the 10-year period of 2010 through 2020.

Table 4 provides some extra clarity on the variability of LFG generation estimates for the lowest and highest scenarios.

The key findings are:

– Waste diversion initiatives by COT could have a large impact on total LFG generation potential, especially in later years. By 2050, the difference could be as large as approximately 2,200 scfm of LFG.

– However, sizable differences in LFG generation potential only start to emerge after 2030, after the effects of population growth and waste diversion have time to compound, and the waste has time within the Landfill to reach maximum LFG generation.

– GCCS and LFG utilization infrastructure sized to capture up to 4,000 scfm would be resilient to potential influences from waste diversion initiatives and population growth. That is, sizing any larger than 4,000 scfm could result in a situation where the infrastructure is ‘overbuilt’ for the actual amount of gas being generated, and result in sunk capital investment. Noting that 100 percent capture efficiency is not usually possible in practice, sizing of infrastructure slightly below 4,000 scfm would be prudent.

– The current GCCS may be performing at lower than optimal conditions as evidenced by its relatively low collection efficiency (actual LFG capture divided by theoretical LFG production). In 2020, an average of 896 scfm

GHD | City of Tucson | 11225318 | Los Reales Landfill 15 This document is in draft form. The contents, including any opinions, conclusions or recommendations contained in, or which may be implied from, this draft document must not be relied upon. GHD reserves the right, at any time, without notice, to modify or retract any part or all of the draft document. To the maximum extent permitted by law, GHD disclaims any responsibility or liability arising from or in connection with this draft document.

of landfill gas was collected and routed to the open flare for destruction, indicating a capture efficiency of about 26 percent. This is lower than typical collection efficiencies which range from 60 to 85 percent, with an average of 75 percent most commonly assumed1.

The full set of supporting calculations and LandGEM model reports for this evaluation is provided in Appendix A.

Figure 4 LFG Generation Estimates for All Waste Diversion AND Population Growth Scenarios

Table 4 LFG Generation Estimates – Low, Middle and Upper Range

Bound Scenario Predicted Landfill Gas Generation (SCFM)

2030 2040 2050

Lower Low population growth High organics diversion (Dashed teal line in Figure 4)

4,076 4,236 4,207

Median Average population growth Medium organics diversion (Thick pink line in Figure 4)

4,200 4,625 4,840

Upper High population growth No additional diversion (Thin black line in Figure 4)

4,360 5,341 6,412

1 USEPA - AP-42 Compilation of Air Pollutant Emission Factors, Section 2.4

GHD | City of Tucson | 11225318 | Los Reales Landfill 16 This document is in draft form. The contents, including any opinions, conclusions or recommendations contained in, or which may be implied from, this draft document must not be relied upon. GHD reserves the right, at any time, without notice, to modify or retract any part or all of the draft document. To the maximum extent permitted by law, GHD disclaims any responsibility or liability arising from or in connection with this draft document.

4.6 Existing Collection System Review

As indicated above, the collection system installed at the Landfill may be currently performing at less-than-optimal conditions. The Landfill cell designations are shown on Figure 5. Table 5 below summarizes the status of vertical gas wells operating at the Landfill as well with a designation of ‘active’ or ‘inactive’2. The table indicates that out of 119 installed wells, only 33 are currently active (or 28 percent of the total). Based on conversations with COT personnel, wells may be inactive for a variety of reasons which include, but are not limited to:

– A well is located in an area that is no longer producing good quality gas (i.e., high in O2 and N2 content)

– A wellhead is damaged

– A lateral/pipe to gas well is pinched (i.e., not producing vacuum)

– Excessive air infiltration from Landfill surface

– A well is “watered out”, i.e., contains high liquids

Table 5 Landfill Gas Well Operating Status and March 2021 Wellfield Data

Landfill Area Total Area

Activ e

Wells

Inactive Wells

Total Wells

Methane Concentration (%) Flow per well (SCFM)

< 45% 45-49.9

50-54.9

> 55% 0-10 10-20 > 20

(Acres) (#) (#) (#) P F G E P F G/E

Old / Unlined Area

145 17 61 78 9 3 5 0 4 5 8

Cell 1/2/3 77 16 25 41 2 2 1 7 5 0 11

Cell 4A/4B 61 0 0 0 0 0 0 0 0 0 0

Totals 283 33 86 119 11 5 6 7 9 5 19 Note: P=Poor, F=Fair, G=Good, E=Excellent

In order to assess the effectiveness of the existing…