NOVEMBER 2020

INVESTOR PRESENTATION

FORWARD LOOKING STATEMENTS

2

The statements contained in this presentation that are not purely historical are forward-looking statements. Our forward-looking

statements include, but are not limited to, statements regarding our or our management team’s expectations, hopes, beliefs, intentions or strategies regarding the future. The information included in this presentation in relation to Atlas has been provided by

Atlas and its management team, and forward-looking statements include statements relating to Atlas’ management team’s expectations, hopes, beliefs, intentions or strategies regarding the future. In addition, any statements that refer to projec tions,

forecasts or other characterizations of future events or circumstances, including any underlying assumptions, are forward -looking statements. The words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “ intend,” “may,” “might,” “plan,” “possible,”

“potential,” “predict,” “project,” “should,” “would” and similar expressions may identify forward -looking statements, but the absence of these words does not mean that a statement is not forward-looking. The forward-looking statements contained in this presentation

are based on our current expectations and beliefs concerning future developments and their potential effects on us. There can be no assurance that future developments affecting us will be those that we have anticipated. These forward-looking statements involve a

number of risks, uncertainties (some of which are beyond our control) or other assumptions that may cause actual results or performance to be materially different from those expressed or implied by these forward-looking statements. These risks and

uncertainties include, but are not limited to: (1) the ability to maintain the listing of the Company’s shares of Class A commonstock and warrants on Nasdaq; (2) the ability to recognize the anticipated benefits of the business combination or acquisitions, which may

be affected by, among other things, competition, the ability of the Company to grow and manage growth profitably, maintain relationships with customers and suppliers and retain management and key employees; (3) costs related to the business

combination and acquisitions; (4) changes in applicable laws or regulations; (5) the possibility that the Company may be adve rsely affected by other economic, business, and/or competitive factors; and (6) other risks and uncertainties indicated from time to time in

the Company’s filings with the U.S. Securities and Exchange Commission, including those under “Risk Factors” therein. You arecautioned not to place undue reliance on any forward-looking statements, which speak only as of the date of this presentation.

Except as otherwise required by applicable law, we disclaim any duty to update any forward-looking statements, all of which are expressly qualified by the statements in this section, to reflect events or circumstances after the date of this presentation.

PRESENTERS

Joe BoyerChief Executive Officer

30+ years of experience

Oversaw the delivery of infrastructure

planning, engineering, architecture, construction management,

environmental consulting and program management services as

CEO, Atkins North America

Previously held the position of

President of Shaw Environmental & Infrastructure’s Federal division

David QuinnChief Financial Officer

25+ years of experience in the

construction, engineering and technical services industries

Previously served in Senior

Executive roles at the Shaw Group and Atkins North America, most

recently in Chief Financial Officer and Chief Operating Officer capacities.

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OVERVIEW

INVESTMENT HIGHLIGHTS

KEY FINANCIALS

TABLE OF CONTENTS

1

2

3

4

TESTING, INSPECTION & ENVIRONMENTAL CONSULTING

ESSENTIAL PROVIDER OF

MISSION CRITICAL SERVICES

HIGH QUALITY CUSTOMER AND WORK MIX

ATLAS OVERVIEW

90% Time & Materials

70% Existing Structures

9,000+ Annual

Customers

50,000+ Annual

Projects

<$10k+ Average

Project Size

Materials Engineering & Testing

Environmental Services

Construction Quality Assurance

Disaster Response & Recovery

ENGINEERING, PLANNING & DESIGN

Engineering & Design Services

Program Management

Construction Support Services

5

A LEADING NATIONAL TECHNICAL SERVICES PLATFORMSpecialized provider of testing, inspection, environmental and engineering services to support and maintain critical infrastructure

$456M

Gross

Revenue1

17.5%

Adj. EBITDA

Margin1,2

$638M

Backlog

1. Based on LTM Q3 2020.2. Adj. EBITDA Margin calculated as LTM Q3 2020 Adjusted EBITDA / LTM Q3 2020 Net Revenues.

WHO WE AREValues-driven approach

We work together as partners, doing what we say with full

accountability.

Always striving for the highest quality, we ensure greatness

inspires all our work.

We enhance quality of life. We value people and safety above

all else.

As our hallmarks, we act with compassion, empathy and

respect.

Life Heart

Trust Mastery

6

VISION

We strive to be the most sought-after infrastructure and environmental solutions brand, known for our unique values-driven

approach and brought to life by the industry’s most exceptional people.

PURPOSE BUILT PLATFORMA modern approach backed by a legacy of excellence

2016 2017 2018 2019 2020

Forming the

Strategy

Establishing

the Platform

Executing the

Atlas Playbook

Creating

National Scale

Completed

Public Listing

National Scale

Platform

Created the Atlas

playbook and

initiated M&A

discussions to

create the platform

Acquired three

regional market

leaders in

Texas, Georgia

and California

Integration of platform

and cross-selling

jumpstarted backlog

growth

Merger with ATC

Group Services

established

national platform

Acquisition of Long

Engineering, Alta

Vista1 & WesTest1

Completed Public

Listing

Nasdaq: ATCX

71 Alta Vista & WesTest acquisitions expected to close by end of 2020

ROBUST FUNDAMENTALS SUPPORT VALUATION UPSIDE

Strong Growth Profile1,2

Attractive Margin Dynamics1,2

25%

14%

ATCX Key Peers

2019 Net Revenue Growth Versus Peers

25%

7%

ATCX Key Peers

2019 Adj. EBITDA Growth Versus Peers

17%

12%

ATCX Key Peers

2019 Adj. EBITDA Margin Versus Peers

8

Enterprise Value / 2020 Adj. EBITDA Versus Peers4,5,9

1. Net Revenue figures used where available and Adjusted EBITDA margin calculated as % of Net Revenue where available.2. Net Revenue is not a financial measure determined in accordance with GAAP. For a definition of Net Revenue and a reconciliation to our most directly

comparable financial measure calculated and presented in accordance with GAAP, please see the Appendix included herewith.3. Key Peers: NV5 Global, Tetra Tech, and ICF International.4. Source: FactSet, Capital IQ and company filings as of 11/11/2020.5. Multiples based on Enterprise Value as of 11/11/2020.6. Engineering & Design (“E&D”) Peers: NV5 Global, Tetra Tech, Parsons Corporation, Stantec, WSP Global, Jacobs Engineering Group and AECOM.7. Testing & Inspection (“T&I”) Peers: Applus Services, S.A., ALS Limited, Bureau Veritas S.A., Intertek Group plc and SGS S.A.8. Professional Services Peers: Accenture plc, Booz Allen Hamilton, CGI, FTI Consulting, Huron Consulting Group and ICF International.9. Adjusted EBITDA is not a financial measure determined in accordance with GAAP. For a definition of Adjusted EBITDA and a reconciliation to our most

directly comparable financial measure calculated and presented in accordance with GAAP, please see the Appendix included herewith.

10.0x

13.5x

11.2x

13.9x 13.7x

ATCX Key Peers E&D Peers T&I Peers Professional

Services Peers

9

CURRENT MARKET LANDSCAPE Non-discretionary and government-based work remained strong throughout 2020

Atlas’ mission critical services support

infrastructure and other essential

industries

NET REVENUE BY END MARKET1,2

1. Net Rev enue is not a f inancial measure determined in accordance with GAAP. For a definition of Net Revenue and a reconciliation to our most directly comparable financial measure calculated and presented in accordance with GAAP,

please see the Appendix included herewith.2. Management estimates based on FY 2019.

• Transportation

• Government

• Education

• Water

• Commercial

• Industrial

No material contracted backlog

projects have been cancelled

Highly variable cost structure to align

resources with market activity

Preciously enacted cost savings

to benefit 2020E by $6-8M

~50%

Government

Based

No Material

COVID-19 Impact

Government-based volume

higher YoY in Q3 2020 YTD

Localized

COVID-19 Impact

Localized geographic work

delays, most notably in the

Northeast and Northern California

~50%

PRIVATE SECTOR

~50%

GOVERNMENT-

BASED

36%

15%

38%

6%4%

OVERVIEW

INVESTMENT HIGHLIGHTS

KEY FINANCIALS

TABLE OF CONTENTS

1

2

3

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INVESTMENT HIGHLIGHTS

Purpose-built platform delivering highly-technical, mission critical infrastructure & environmental services

Entrenched long-term relationships with high quality customers base

Resilient business model driven by repeatable, contracted revenue base derived mostly from non-

discretionary projects

Proven ability to execute multi-pronged growth strategy

Continued growth in backlog provides Atlas with one of the strongest backlog positions in

the technical services space

Disciplined deleveraging M&A approach

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Industry leading gross margins and EBITDA margin profiles, driving substantial free cash flow

36%

15%

38%

6%4%

• Materials, Engineering & Testing

• Environmental Services

• Design / Construction Quality Assurance

• Disaster Response & Recovery

• Engineering & Design Services

• Program Management

• Project Support Services

Example of Atlas Services by End Market Key Tenets of Atlas Services

Engineering, Planning & Design

1. Trusted Advisor – Services ensure safety of employees, customers and the general public

2. Technical Expertise – Highly-skilled employee base able to add value to a diverse array of projects

3. Compliance Driven – Non-discretionary, highly recurring services

4. Local Knowledge and Relationships – Extensive knowledge and expertise of local regulations and codes

5. National Scale and Reputation – Strategic footprint enables the Company to deliver highly customized solutions nationwide

6. No Construction – Atlas does not perform construction or take construction risk

Net Revenue by Service1,2 Net Revenue by End Market1,2

Note:1. Management estimates.2. Excludes the pro forma impact of Long Engineering acquisition.

BROAD RANGE OF HIGHLY TECHNICAL, MISSION-CRITICAL SERVICESDiverse set of highly technical infrastructure and environmental services

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• Transportation

• Government

• Education

• Water

• Commercial

• Industrial

80%

20%Testing,Inspection &EnvironmentalConsulting

Engineering,Planning &Design

Testing, Inspection & Environmental Consulting

Atlas Services

Reinforced concrete testing and inspection for facility renovations,

environmental & industrial hygiene

Structural inspection and materials testing for tanks and retention ponds

Geotechnical and structural inspection for renovations and expansions,

environmental & industrial hygiene

Materials testing, QA, engineering, inspection and design for road, bridge,

and airport modif ications, environmental and program management Transportation

Commercial

Industrial

Government

Education

Water

System-w ide operations and maintenance for remediation systems,

environmental & industrial hygiene

Program management, design, and oversight for publicly funded projects,

environmental & industrial hygiene

LONG-TERM CUSTOMER RELATIONSHIPS AND DIVERSE REVENUE BASEAtlas’ technical expertise, performance and strong relationships have led to decades-long relationships with customers, providing a strong base of repeating revenues and leading backlog position

13+

15+

15+

18+

20+

25+

25+

25+

30+

30+

1

2

3

4

5

6

7

8

9

10 Transportation

Government

Commercial

Education

Water

Industrial

Blue-Chip Customer Base(Relationship Length in Years for Top 10

Customers by Net Revenue)

Across Diverse End Markets(Representative Customers)

Tenured Relationships Driving Consistent Demand

(% of 2018A Net Revenue from top 15 customers)1

1. Approximate values based on historical trends.2. Repeat customers defined as those that have used Atlas services in the prior year.

30+ Years

27%

20 - 30

Years25%

10 - 20

Years44%

<10 Years

4%

Entrenched, Highly Repeating and Diversified Customer Base

• 9,000+ Annual Customers

• ~90% Revenue from Repeat Customers2

• 50,000+ Annual Projects

• 90%+ T&M or Cost-Plus Contracts

13

RESILIENT BUSINESS MODELResilient, purpose-built platform delivering highly-technical, mission critical infrastructure & environmental services

Fully-funded backlog

provides multi-year view

of work pipeline

Government-based

work grows steadily

throughout cycles

Geographic exposure

to well-funded

regions in the U.S.

Testing, inspection and

environmental work is

regulatory and

compliance driven

Work performed for

repeat customers

~90%

Work performed on

existing assets and

structures

~70%

Diverse and resilient

end markets, with

approximately half of

work government-based

~50%

Highly variable cost

structure and low

capex needs

enhances resiliency

BACKLOG DRIVEN CYCLE-TESTED HIGH GROWTHMISSION CRITICAL ASSET-LIGHT

14

Purpose-built platform

through seven accretive

acquisitions with a

pipeline of additional

opportunities

7Purpose-built platform

through seven accretive

acquisitions with a

pipeline of additional

opportunities

7

BACKLOG DRIVES HIGH BUSINESS CONFIDENCE Record backlog fueled by key wins across Atlas service offerings and geographies

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BACKLOG

2017

$502M

Q3 2020

$638M

Building strong pipeline of

work, providing favorable

trajectory into 2021

Q3 KEY WINS VALUE SERVICES

Gwinnett County, GA GDOT Highway $7M Program Management

United States Army Corp of Engineers,

Los Angeles District$5M

Materials Engineering,

Consulting & Testing

Construction Management

Services for BART Projects$5M

Materials Engineering,

Consulting & Testing

TxDOT Highway $3.5MConstruction Quality

Assurance

County of Los Angeles

Department of Public Works$3M

Materials Engineering,

Consulting & Testing

Environmental Protection Agency –

Groundwater Treatment$2.5M

Environmental

Services

United States Postal Service –

Water/Tank Compliance$2.5M

Environmental

Services

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STRATEGIC GROWTH TRAJECTORYProven execution of growth plan through organic and M&A means

20161

$228M

2017

$278M1

2018

$426M

2019

$471M1

2020

~$459M3

2021Ongoing execution of organic

and M&A growth strategy

Gross Revenue2

1 2016 Includes ATC as the accounting predecessor. 2017 includes partial year impact of acquisitions. 2019 Formal y ear of merger between Atlas and ATC.

2 GAAP based historical revenue.3 Midpoint of FY2020 outlook range for gross revenue, does not include planned WesTest acquisition.

NATIONAL SCALABLE GROWTH PLATFORMExecuting multi-pronged growth strategy across expanded footprint

National Platform of Scale

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Source: 1. Global Market Insights 2. American Society of Civil Engineers 3. Orbis Research

Key Market Tailwinds

• Favorable secular trends independent of the broader economy

• 40% of T&I services outsourced and increasing1

• $4.6tn needed US infrastructure2

• $30bn annual T&I and environmental consulting market3

Cross-Selling and

National Accounts

• Cross-selling and national accounts strategy driving wins

• Self-performing more work to increase share of wallet share

• Expanded capabilities to cross-sell more services

3

1Growth in Large Contracts

• Leveraging national scale and local expertise to win premier projects >$5 million

• Service expansion allows Atlas to bid for larger, marquee contracts

• Geographic expansion to pursue additional large-scale contracts

2

Disciplined Approach

to M&A

• Track record of successfully acquiring businesses at accretive valuations

• Strategy of acquiring smaller business at lower multiples and realizing synergies to drive outsized Adjusted EBITDA growth relative to leverage

• Management actively reviews M&A opportunities

4

CAPITALIZING ON KEY MARKET TAILWINDSCompelling investment thesis supported by strong secular trends

America’s Engineering & Construction Infrastructure Condition Report Card

1. Aging Infrastructure – Continued investment and spending programs dedicated to deteriorating

U.S. infrastructure

2. Safety & Reliability – Services ensure safety requirements

3. Regulation & Compliance – Complex regulatory environment requires third-party consultants;

compliance required through a dow nturn

4. Population Growth – Key Atlas geographies include Texas, California, Georgia and New York

5. Environmental, Social and Governance – Increased public aw areness on the sustainability and

societal impact of assets

6. Outsourcing – Mitigates cost and resource allocation associated w ith training programs

7. Technological Innovation – Emerging technologies driving change

Favorable Secular Trends Driving Growth

Source: 1. Global Market Insights 2. American Society of Civil Engineers 3. Orbis Research 4. Wall Street Journal 5. Texas Department of Transportation 6. California Road Repair & Accountability Act 7. New York Department of Transportation

Market Opportunity

Key Geographic Developments

• Constant effort to improve New York’s transportation infrastructure (e.g.

MTA)

• DOT budget forecast of $12.0bn7

• $14bn 20-year infrastructure budget approved in 2018

• Over $130bn estimated backlog for road and bridge repairs6

• TxDOT budget has grow n +70% ($30bn) and staff decreased 15%5

• 2019 Unif ied Transportation Program approves $75bn in projects through

2028

Texas

California

Georgia

New York

• 2015 Transportation Funding Act provides $10bn for infrastructure funding

• Major Mobility Investment Program secures $11bn for large scale projects

40% $4.6tn

$30bn $2tn+

Of testing and inspection services are outsourced1

Spending need for aging US infrastructure through 20252

Proposed federal infrastructure package4

Market for US infrastructure & construction TIC and environmental consulting3

Aviation Public Parks

Bridges

Drinking Water

Energy

Hazardous Waste

Inland Waterways

Levees

Dams

Ports

Rail

Roads

Schools

Solid Waste

Transit

Wastewater

D

C+ C+

D

D

D+

D+

D

D

D+

B

D

D+

C+

D

D-

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Overview of Acquisition Pipeline

Atlas has a well-developed “playbook” of identifying, integrating and scaling its accretive acquisitions

Source: 1. American Society of Civil Engineers, IBIS World

Company / Region Strategic Rationale

SoutheastEnhance program management capabilities with

specialty proprietary services

Southeast Expansion into new growth transportation area

NortheastExpand geographic diversity of service offerings

with client targets

WesternDiversity of services with highly specialized

inspection capabilities

The Atlas Playbook

• Leverage industry relationships to identify leading providers

in targeted markets

• Complete acquisition and maintain branding and local

autonomy while integration commences

• Begin early-stage integration

IDENTIFY

• Transition to the Atlas brand and align management on near

and medium-term vision

• Identify cross-selling opportunities

• Consolidate back-office and other administrative functions

INTEGRATE

• Execute on cross-selling initiatives

• Leverage platform capabilities to expand core competency

• Incentivize sales personnel to drive cross-selling and

educate customers on new capabilities

SCALE

1

DISCIPLINED M&A STRATEGYPursue targeted low-risk bolt-ons that both benefit from and expand national scale

2

3

Illustrative Acquisition Targets

140,000+Companies operating

in a highly fragmented market1

~$100MTotal EBITDA

in Pipeline

20+Total Target

Companies in Pipeline

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OVERVIEW

INVESTMENT HIGHLIGHTS

KEY FINANCIALS

TABLE OF CONTENTS

1

2

3

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TRACK RECORD OF FINANCIAL SUCCESSStrong results achieved through execution of multi-pronged growth strategy

>100%CAGR

30%CAGR

36%CAGR

(Dollars in Millions)

1 Adjusted EBITDA margin calculated as Adjusted EBITDA / Net Revenues.

27%CAGR

$228

$278

$426

$471

2016 2017 2018 2019

GROSS REVENUE NET REVENUE

$174 $195

$302

$378

2016 2017 2018 2019

Adjusted EBITDA & Margin1 GROSS PROFIT

$3 $9

$53

$66

2%

4%

17% 17%

1%

4%

20%

100%

$-

$10

$20

$30

$40

$50

$60

$70

2016 2017 2018 2019

$83

$114

$177

$211

2016 2017 2018 2019

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STRENGTHING AND SIMPLIFYING CAPITAL STRUCTUREStrong cash flow profile, financial flexibility and disciplined capital deployment

(Dollars in Millions)

22

Invest in Growth

AcquisitionsPurpose-built platform with

strong accretive deal pipeline

Maintain capital discipline

Financial Flexibility

Optimize ReturnsPrioritized actions to optimize capital structure and returns

Value-enhancing initiatives

Adj.

Operating

Cash Flow1

LTM $60M

1 Adj. Operating Cash Flow excludes $37.3 million of one-time cash expenses related to acquisitions, the business combination with Boxwood Merger Corp., public company formation costs and 2020 COVID-19 related expenses.2 Net lev erage calculated as (debt – cash) / LTM Covenant Adj. EBITDA including predecessor period of acquisitions.

Balance Sheet

3.8x Net Leverage2

Deleveraging M&A strategy

Liquidity of $42M

23

Q3 2020 HIGHLIGHTSResilient business model, proactive execution and safety-first emphasis drove strong results

• Stronger YoY revenues in government-based work

• Private sector work strengthened as Q3 progressed

• Net revenue at 81% of gross revenues, compared to 78% in prior year quarter, attributable to a higher level of self-performed work

• Adj. EBITDA at 19.4% of net revenues, benefitting from operating efficiencies and previous cost actions

• $16.4 million of operating cash flow generation

• Deleveraging M&A progress: acquisition of Alta Vista, strengthening mix of government-based revenue exposure with deal structured to reduce net leverage

• Backlog up year-over-year to a record $638 million, including $29 million from Alta Vista

• Completed warrant exchange offer in November 2020 as part of broader initiative to simplify capital structure

Gross Revenue

$120.5M

Backlog

$638M

Net Revenue1

$97.9M

Adj. EBITDA1

$19.0M

1. Adjusted EBITDA and Net Revenue are not financial measures determined in accordance with GAAP. For a definition of Adjusted EBITDA and Net Revenue and a reconciliation to our most directly comparable financial measure calculated and

presented in accordance with GAAP, please see the Appendix included herewith.

APPENDIX

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RECONCILIATIONNet Income to Adj. EBITDA and LTM Q3 2020

25

Reconciliation Revenues LTM Q3 2020 Gross Revenues

Reimburseable

Expenses Net Revenues

Nine months ended September 31, 2020 342,503$ (62,550)$ 279,953$

Plus: Quarter ended December 31, 2019 113,014 (20,562) 92,452

LTM Q3 2020 455,517$ (83,112)$ 372,405$

Reconciliation Net Income to Adjusted EBITDA

For the nine

months ended

September 30,

2020

For the quarter

ended December 31,

2019 LTM Q3 2020

Net (loss) income (20,764)$ (5,511)$ (26,275)$

Interest 18,349 1,835 20,184

Taxes - 1,228 1,228

Depreciation and amortization 15,470 4,278 19,748

EBITDA 13,055 1,830 14,885

EBITDA for acquired business

prior to acquisition date 800 579 1,379

Other non-recurring expenses 22,395 14,908 37,303

Non-cash equity compensation 10,995 600 11,595

Adjusted EBITDA 47,246$ 17,917 65,163

Adj. EBITDA % of Net Revenues LTM Q3 2020 17.5%

(Unaudited)

(in $ 000's)