Mainline Excavating, Inc.

Central Pennslyvania commercial excavating

Our History

Mainline Excavating, Inc. is part of the Williams family of companies and has a long history of excellence in construction. Brothers Andrew and Paul Williams founded the design/build construction firm A.P. Williams in 1994. Building upon their success, in 2000 they founded Mainline Excavating, Inc. to provide excavation and site work services. They began Mainline to ensure that their projects, as well as those of their partnering firms, begin with safe, cost-effective and professional excavating and sitework services. In 2019, the Williams brothers founded Williams Site Civil, further expanding their portfolio of services to include civil engineering.

Our Philosophy

With a deep understanding of quality and value as the end goals of every commercial construction project, Mainline Excavating, Inc. is committed to helping you achieve these goals through value-engineering and a high level of expertise to ensure a high-quality finished product.

Our Core Values

Mainline Excavating’s top goal is to deliver our professional excavating services to the highest standards of workmanship and safety. To accomplish this goal, we have an established and prominent set of core values to provide us the parameters to achieve overall excellence.


Openness in communication is paramount to a successful working relationship. We believe in complete two-way transparency for the highest level of integrity and success for each project.


We apply our expertise and ideas to the benefit of the client.


We are deeply committed to delivering the best results, exceeding even the highest expectations for workmanship and professional excavating expertise.


Our integrity is one of our prized signature qualities. Our reputation for doing what we say we’ll do when we say we’ll do it is one that our clients are acutely aware of and one that we constantly strive to live up to.


We embrace the importance of safety and ensure the highest level of safety for our staff, clients and fellow subcontractors.


As a team, one of our goals is to continually improve and constantly strive to learn more, do more and be more for our clients and our community.

We are 100% committed to your success.

Our team of professionals works diligently to value engineer your project’s site layout, grading, utilities, stormwater and infiltration systems, pavement designs and sustainability. Our extensive knowledge of commercial development allows us to contribute to a well-planned, cost-effective project, applying our combined seventy-plus years of engineering and field experience to benefit the project owner’s ROI. We consistently provide cost-saving solutions on every project we undertake, resulting in our clients saving hundreds of thousands of dollars to date.