About Us


Clark Construction Group is one of the most experienced and respected building and civil construction firms in the United States. For over a century, we have been transforming the ideas and visions of our clients into award-winning projects. We build with the intention of exceeding our clients’ expectations for safety, quality, functionality, and aesthetics, and deliver assets that stand the test of time.


We pride ourselves on being a local builder with national reach. Our 4,200 employees are spread across offices and jobsites throughout the United States. Though our presence today is larger than ever before, we are deeply rooted in the communities where we build and live.

Our portfolio features projects of all sizes and levels of complexity — from intricate interior renovations to some of the most complex civil operations in the country, we can build it all — and we do. Clark’s breadth of capabilities ensures that we are able to meet our clients’ needs every time, on every front.

But, more than our extensive portfolio, what truly sets us apart is our people. Their dedication to providing world-class service to our clients, resolve for delivering exceptional work, capacity for innovation and problem solving, and unwavering commitment to improving the communities we serve, make Clark what it is today. 


For over a century, Clark has benefited from energetic, principled, and creative leaders at its helm. These qualities live on today. Clark's executive team brings a diverse set of skills and experience, ensuring a well-rounded perspective on company operations. Our leaders share a common vision and values; they possess a passion for building, a devotion to our clients, a dogged dedication to ensuring the company's — and our people's — continued growth and prosperity, and an enthusiasm for strengthening our communities.

Brian Abt

Brian Abt

Building Group

Brian Abt serves as president of Clark Construction’s Building Group, providing executive management and overseeing national operations for the company’s vertical construction projects.

Clark's Building Group delivers assets of varying types in markets including health care, aviation, mission-critical, public assembly, sports and entertainment, education, residential and mixed-use, office, hospitality, and government across the United States.

Prior to being appointed president of the Building Group, Brian served as the chief executive officer of Clark’s Mid-Atlantic Region where he was responsible for the region’s day-to-day operations, including overall client satisfaction as well as the safety, quality, and timely completion of all projects.

Since joining Clark in 1985, Brian has provided leadership on some of the country’s most notable projects, including Nationals Park, the National Museum of African American History and Culture, the Walter Reed National Military Medical Center, and The Wharf.

Brian earned his bachelor’s degree in civil engineering at the Rensselaer Polytechnic Institute and has completed the Advanced Management Program at Harvard Business School.

Brian is a member of the board for The 2030 Group, an organization committed to advancing regional solutions that enable a strong regional economy, strengthen continued employment opportunities, sustain economic development, and ensure high quality of life for current and future residents in the Washington DC-area.


David Beck

David Beck

Division President,
Risk Management

David Beck oversees risk management at Clark Construction Group. 

David is responsible for insurance procurement and administration, as well as implementing strategies to minimize risk on new and ongoing work.

Prior to joining Clark, David served as a partner at the law firm of Pillsbury Winthrop Shaw Pittman, where he primarily focused on construction and insurance matters.

David earned his bachelor’s degree in business from the University of Utah and a juris doctor from the College of William & Mary.


Sameer Bhargava

Sameer Bhargava

Chief Executive Officer,
Asset Solutions Group

Sameer leads Clark’s Asset Solutions Group, a division that offers technology, advisory, capital, and turnkey services spanning an asset’s lifecycle. In this role, he oversees the strategic direction of Edgemoor Infrastructure & Real Estate, S2N Technology Group, Carta Advisors, and Coda.

Sameer, a member of Clark’s executive leadership team, is also responsible for the organization’s corporate planning, strategy, innovation, risk management, and information technology functions.

Sameer previously served as Clark’s chief financial officer where he was responsible for overseeing the company’s financial activities.

Prior to joining Clark, Sameer served as managing director and director of corporate development at The Carlyle Group, one of the world’s largest private equity firms, where he focused on firm strategy and planning, firm acquisitions, fundraising initiatives, new product development, and strategic relationships. 

Sameer’s career has also included roles with Bain Capital, Advent International, and McKinsey & Company.

Sameer earned his bachelor’s degree in biology from Harvard University and a master of business administration from Harvard Business School.

Sameer serves on the board of The Potomac School, and as part of the Dean’s Leadership Council at Harvard University’s Graduate School of Design. In 2019, Sameer was a Washington Business Journal C-Suite Awards recipient.


  • Bachelor of Science, Biology Harvard University
  • Master of Business Administration Harvard Business School
William Calhoun

William Calhoun

Executive Vice President &
Vice Chairman

William (Bill) Calhoun is responsible for driving Clark Construction Group's strategic direction including the acquisition of new work and identifying new and emerging markets.

Working with Clark’s divisions and business units, Bill ensures that Clark has the right strategy in place to exceed the needs and expectations of its clients.

Over the last three decades, Bill has used the principles of integrity, accountability, relationship building, business acumen, and philanthropy to lead the Clark team.

Bill began his career at Clark in 1983, and through successive assignments leading the development and delivery of projects across the country, was promoted to executive vice president in 2003.

Bill has provided leadership on numerous high-profile projects, including the National Geospatial-Intelligence Agency New Campus East, Brooke Army Medical Center, Capital One Arena, U.S. Coast Guard Headquarters, New Terminal at Kansas City International Airport, and Washington State Convention Center Addition.

Bill earned his bachelor’s degree in civil engineering from the Georgia Institute of Technology. He also completed the Advanced Management Program at Harvard Business School.

Bill is on the Corporate Advisory Board of So Others Might Eat and currently serves on the President’s Advisory Board for the Georgia Tech Advisory Board (GTAB). He is also a member of the Construction Industry Round Table, has been elected to the National Academy of Construction, and serves on the steering committee for the Construction Industry Ethics & Compliance Initiative.

Bill is a Glenn L. Martin Medal recipient from the A. James Clark School of Engineering at the University of Maryland and has been inducted into Georgia Institute of Technology's College of Engineering Academy of Distinguished Engineering Alumni.


  • Bachelor of Science, Civil Engineering Georgia Institute of Technology
  • Advanced Management Program Harvard Business School
Brian Flegel

Brian Flegel

Executive Vice President,
National Acquisition and Development

Brian Flegel oversees Clark Construction Group’s national acquisition and development strategy, supporting clients nationwide with a focus on new regional markets.

Brian works with Clark’s divisions and business units from the earliest stages of project identification to ensure the right strategy and the right team members are in place to exceed the needs and expectations of clients.

An industry veteran, Brian has led teams on some of Washington, DC’s most iconic buildings including the National Museum of African American History and Culture and the Museum of the Bible.

Prior to being named executive vice president, Brian served as senior vice president of talent where he provided executive direction for Clark's human resources strategy and was responsible for attracting, retaining, developing, and engaging the industry's best talent.

Brian earned his bachelor’s degree in architectural engineering from the Pennsylvania State University.

Brian serves on the board for Higher Achievement – DC and the Arnold Foundation (Lumberton, TX) and is an active volunteer with The Fuller Center for Housing.


  • Bachelor of Science, Architectural Engineering The Pennsylvania State University
Jay Grauberger

Jay Grauberger

Executive Vice President,
Corporate Affairs

Jay Grauberger is responsible for building and maintaining relationships with Clark Construction Group’s key stakeholders through various client service and partnering initiatives, as well as government and community relations programs.

Jay also provides leadership and oversight for Clark’s Strategic Partnership Program, which serves as the centerpiece of our commitment to small business development across the country.

Prior to his time at Clark, Jay served as chief marketing officer for a large Washington, DC law and lobbying firm, and prior to that, as a director at a global accounting and consulting firm.

Jay earned his bachelor‘s degree from Hamilton College and a master's degree from the University of Michigan.

He currently serves on the Strathmore Hall Foundation board, the Greater Washington Board of Trade, and the Federal City Council.


Sara Guthrie

Sara Guthrie

Senior Vice President,
Communications & Marketing

Sara Guthrie is responsible for shaping Clark Construction Group's communications strategy and the company's marketing efforts.

In her role, Sara oversees all aspects of external and internal communications, including media relations, digital communications, branding, employee communications, and corporate events. Sara also leads the company's proposal development strategies with an overall focus on product positioning and propelling Clark's reputation as a trusted asset delivery company.

She is passionate about showcasing Clark's value proposition and ensuring that the talented people that make up the Clark team feel engaged. 

Sara earned her bachelor's degree in government from the University of Virginia.


Mark Hamberlin

Mark Hamberlin

Executive Vice President &
Chief People Officer

Mark Hamberlin provides executive direction for Clark Construction Group’s human resources strategy and operations.

Mark is responsible for aligning talent, culture, and organization in order to attract, retain, develop, and engage the best talent for Clark. His role also encompasses talent acquisition and management, training and development, organization development, employee engagement, total rewards, and employee policies.

Prior to joining Clark, Mark served as vice president of global talent acquisition for Danaher, a global science and technology company. Mark’s career has also included human resources and finance leadership roles at Cisco Systems, Coach Leather, and Hallmark Cards.

With decades of human resources experience, Mark is instrumental in fostering a strong alignment between business strategy, talent management, and company culture. He is also focused on driving growth and development of the Clark team.

Mark earned his bachelor’s degree in French, with minors in business and psychology, and a master’s degree in organizational behavior from Brigham Young University.

Mark serves on the MBA Advisory Board for the Marriott School of Management and is active with local community service and youth groups.


  • Bachelor of Arts, French Brigham Young University
  • Master of Organizational Behavior Brigham Young University
Chip Hastie

Chip Hastie

Executive Vice President,
Project Development

Chip Hastie is responsible for project development at Clark Construction Group, ensuring that the company has the best strategy and plan to set every project up for success.

Chip works with divisions and business units across Clark to optimize project planning through approaches to preconstruction, design-build management, purchasing, and estimating. Chip also provides executive leadership for the Sustainability and VDC Departments at Clark.

Since joining Clark in 1999, Chip has been involved with many signature projects at Clark – including the Southeast Louisiana Veterans Healthcare System Replacement Hospital, the Governor George Deukmejian Courthouse, and PETCO Park.

For Chip, planning is a cornerstone of success at Clark. With "a plan to win”, Clark is able to execute brilliantly for its clients and positions the company for long-term growth.

Chip earned his bachelor’s degree in civil engineering from the University of Virginia and a master of business administration from the University of Southern California.


  • Bachelor of Science, Civil Engineering University of Virginia
  • Master of Business Administration University of Southern California
Kelly Hernandez

Kelly Hernandez

Chief Financial Officer

Kelly Hernandez is responsible for Clark’s overall financial health.

In her role, Kelly oversees the company’s financial functions, including tax, accounting, financial planning and analysis, shared services, cost engineering, operational finance and compliance, and strategic purchasing functions.

Prior to joining Clark, Kelly served as the chief financial officer for the engineering solution company Leido’s Civil Group. Kelly’s career has also included roles with Deutsche Bank, Credit Suisse, Advanced Micro Devices, as well as other technology companies in Silicon Valley. 

Kelly holds a bachelor of science degree in computer and electrical engineering from Purdue University and a master’s degree in business administration from the University of California, Berkeley, Haas School of Business.


Robert Moser, Jr.

Robert Moser, Jr.

Chief Executive Officer

Robert (Robby) Moser, Jr. is responsible for setting the strategic priorities for Clark Construction Group and its subsidiary and affiliate companies, which includes Guy F. Atkinson Construction, Shirley Contracting Company, S2N Technology Group, C3M Power Systems, Edgemoor Infrastructure and Real Estate, Clark Civil, Clark Concrete, and Coda. 

As chief executive officer, Robby provides executive direction for the company's national operations, which total $5 billion in revenue per year.

Throughout his tenure in the industry, Robby has led efforts to secure and build all manner of projects from professional sports venues to hospitals to transit infrastructure.

Under Robby’s leadership, Clark has partnered with clients to create monumental and critical assets – including the National Museum of African American History and Culture, Fort Bliss Replacement Hospital, SR-91 Corridor Improvement, Salesforce Tower, CSX Virginia Avenue Tunnel, and Chase Center.

Robby is passionate about providing a superior client experience where customers feel engaged, keeping the safety of craftworkers at the forefront of every project, ensuring that the quality of Clark products is unparalleled, creating opportunities for Clark team members to grow, and ensuring the Clark team has the resources necessary to execute brilliantly in all that they do.

Robby earned his bachelor’s degree in civil engineering from the Virginia Polytechnic Institute and State University.


John O’Keefe

John O’Keefe

Infrastucture Group

John O’Keefe serves as president of Clark Construction’s Infrastructure Group, overseeing the company’s heavy-civil construction portfolio and providing executive management for the organization’s self-perform operations.

In his role, John works with teams across the organization to deliver some of the most sophisticated highway, bridge, transportation, tunnel, and water/wastewater projects in the country.

The Infrastructure Group includes all of Clark’s heavy-civil and self-perform entities including Guy F. Atkinson Construction, Shirley Contracting Company, C3M Power Systems, Clark Water, Clark Civil, Clark Concrete, and Clark Foundations.

John previously served as Clark’s chief operating officer, working with regional executives to optimize project performance and ensure financial, schedule, safety, and quality goals were achieved.

John has leveraged his industry experience on many building and civil signature projects – including the Downtown Bellevue Tunnel, I-15/I-215 Devore Interchange Improvements, Two Liberty Place, Market Square North Mixed Use, 2400 M Street, Brooke Army Medical Center, and the National Museum of the American Indian.

John earned his bachelor’s degree in architectural engineering from the Pennsylvania State University and has completed the University of Virginia Darden School of Business Executive Program.

He is a member of the Construction Industry Ethics and Compliance Initiative and the Pennsylvania State University Partnership for Achieving Construction Excellence (PACE) program. He also is a member of the Penn State University Industrial and Professional Advisory Council.


  • Bachelor of Architectural Engineering The Pennsylvania State University
  • The Executive Program Darden School of Business, University of Virginia
Susan Williamson Ross

Susan Williamson Ross

Executive Vice President

Susan Williamson Ross is a member of Clark Construction Group’s Board of Managers and the lead trustee for the company’s retirement plans.

Susan also serves as the president and chief executive officer of the 1906 Group, a privately-held company engaged in real estate, construction, and asset management.

Susan previously served as the chief administrative officer for Clark where she oversaw human resources, corporate communications, corporate philanthropy, community relations, and office services.

Susan is currently a board member and member of the Executive Committee of the University of Virginia Foundation, a founding board member of Jubilee to College, and the former president of the board of the School of Architecture at the University of Virginia. She also serves as an independent director for NVR, Inc. and volunteers as an ESL teacher at the Washington English Center.

Susan earned her bachelor's degree in architecture from the University of Virginia and is a registered architect.


  • Bachelor of Science in Architecture University of Virginia
  • Registered Architect

Putting Safety First

To us, no project is successful unless it is built safely. We believe that all accidents and unsafe work practices are preventable, and through proper planning and training, employee engagement and empowerment, and constant vigilance, we can ensure a safe workplace for everyone.

Delivering Excellence

We are uncompromising in our pursuit of excellence, and we take great pride in delivering high-quality assets and experiences. We continually find ways to work faster and smarter, respond to challenges with ingenuity and innovation, and earn the trust and respect of our clients and stakeholders. We believe in doing things right the first time, every time, and place value on diligent planning and fostering relationships.

Creating Opportunities for Our People

At Clark, our people are as exceptional as the projects we build. It is our obligation to provide challenging and rewarding opportunities - without barriers - to help our people grow both professionally and personally.

Acting With Integrity

A deep commitment to ethics and fairness guides how we do business. We hold our work — and our people — to the highest professional standards. At the end of the day, we believe that doing the right thing and treating everyone with respect is the only way to do business.

Building Inclusive and Diverse Community

We are committed to advancing inclusion and diversity for our company, our industry, and in our communities. We embrace the opportunity to make a meaningful and positive impact by creating an inclusive and respectful workplace, supporting small businesses and workforce development, and giving back through community service.

About — Inclusion & Diversity

Inclusion & Diversity

At Clark, we are committed to advancing inclusion and diversity for our company, our industry, and in our communities. By embracing uniqueness, fostering a culture of acceptance, and engaging with our employees and partners, we provide an environment where everyone can thrive, as we succeed together as #OneClark. 

We value inclusion and diversity as essential to our mission of building what matters, together.

Learn More About I&D at Clark


People are at the core of everything we do. For over a century, the expertise and ingenuity of Clark Construction employees propelled us to deliver projects across the country and achieve our clients’ goals. On par with our commitment to building excellence is our commitment to safety. At the core of Clark’s approach to building safely is fostering camaraderie and a genuine concern for the person working next to you.

To us, no project is successful unless it is built safely. We believe that all accidents are preventable, and through proper planning and training, employee engagement and empowerment, and constant vigilance, we can ensure that everyone leaves the jobsite in the same condition that they arrived.

This grassroots approach builds trust among teams and empowers employees to embody our “All Hands, All Heads, All Hearts” ethos on every jobsite. Where trust is the norm, teams are more likely to offer honest feedback or elevate concerns if they see something unsafe.

Learn about Clark's Response to COVID-19


Clark has been helping our clients build for over a century. American owned and operated since 1906, we have grown from a small local excavator into one of the most capable and trusted providers of construction services. As one of the nation’s most established firms, we have a long-term perspective that is invaluable in our industry.