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About GWM Earthworks

We’re a locally focused excavation company serving Amherst, NH and surrounding towns. After 25 years in business, we’ve learned that honest assessments, clear communication, and careful work are what matter most to homeowners. From complete septic system replacement to grading and site prep, we bring the right equipment, the right plan, and the respect your property deserves.

Our Story & Experience

GWM Earthworks is led by Garrett Mayo, a hands-on owner-operator who still shows up on site to walk the project with you. You’ll work with a small, experienced crew that values safety, neatness, and keeping neighbors happy. We use well-maintained equipment sized for residential access, plan safe travel paths, and protect lawns and hardscapes during work.

Early Roots

Founder Garrett Mayo grew up working outdoors, moved to Amherst in 2000, and started what became GWM Earthworks over two decades ago.

Craft and Capability

Year-by-year, we added equipment and expanded from landscaping into full earthworks—learning septic systems, drainage, and site work alongside established excavation pros.

Licensed Septic Expertise

We hold a New Hampshire Septic System Installer License and manage septic replacements in coordination with permitted designers and local inspectors.

Today

We focus on residential earthworks—leach fields, drainage, shed pads, and yard expansion—bringing local knowledge of soils, rock, and terrain to every job.

Why Choose GWM Earthworks

Education-first approach:

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We explain what’s happening underground and why a particular solution fits your property.

Licensed and insured:

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NH Licensed Septic Installer; fully insured for residential excavation work.

Transparent Process:

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Straightforward scopes, realistic timelines, and line-item estimates—no surprises.

Minimal Yard Disruption

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Thoughtful access, clean staging, erosion controls, and thorough site restoration.

Locally Grounded:

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Amherst-based with knowledge of town processes, soils, and inspectors across nearby communities.

Ready to Talk About Your Project?

Have a septic, drainage, shed pad, or yard expansion project in mind? Request a quote and include photos if you have them—we’ll respond within 24 hours to coordinate next steps. Prefer a call? Reach us at 603-801-3385 or GWMLANDSCAPING@gmail.com.