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BASIC CONSTRUCTION BLOG

Does Your Grading Contractor Understand the Local Soil Conditions?

Posted by Derek Patterson   8/26/14 2:17 PM

Not All Grading Contractors Are Alike

grading contractor Newport News

Whether you are trying to develop a sprawling commerce park or you’re clearing thousands of acres for a new highway project, land grading is important for protecting areas from erosion and the buildup of runoff water. Grading contractors are responsible for ensuring that a construction site is built on stable ground today and that it maintains this composition for years to come. This long-term stability requires a complex understanding of the local soil, how it erodes, its drainage qualities and overall stability. The best grading contractors have deep knowledge of the local soil’s composition and nuances, and have developed best practices for site grading within that context.

Know Your Soil

Certain types of problem soils can make grading a site challenging and expensive. Issues like soil type, the presence of ledge, high water tables, and poor drainage can all complicate construction and drive up costs.

Soils have a mix of particles from extremely fine clays and fine silts to course sand and gravel. You can get a pretty good idea of the soil type by examining a handful of soil taken from below the topsoil, the dark, organic matter that’s usually no more than 6 to 10 inches deep. However, you cannot see the individual particles in soils high in clay. When squeezed, this soil feels smooth and can be rolled into thin shapes. The major soil associations found in the City of Newport News are moderately well drained fine loamy and clay-like soils, and poorly drained clay soils on gently sloping uplands. Soils with high clay content tend to hold a lot of water and drain poorly. Soft clays have limited load bearing ability, while expansive clays expand when wet with enough force to destroy foundations and shrink when dry causing excessive settlement.

The Effect of Soil Quality on Grading

Poor quality soil is a real issue for site grading. If not recognized and addressed, soils rich in clay can lead to structural compromises. Landscaping and grading can suffer, resulting in pooling of irrigation waters and poor storm runoff.

Before construction begins, the best practice is to research and assess the soil quality. A soil engineer can determine the depth to ground water, settlement characteristics and what is needed to bring the site up to code. But before calling in the engineer, it can be easy for a knowledgeable grading contractor to inspect the site and make some early determinations on soil quality.

There are two main factors to consider when assessing soil quality: type and substance. Soil type is categorized as either “virgin” or “fill”. Virgin soil has never been disturbed and in general is more compact and consistent. Land that has had fill brought in will be an unreliable factor, as you can’t be sure of the quality of the fill, and it may need to be compacted as part of the grading process.

Not all grading contractors have the experience, capability, equipment, and personnel required for high quality grading and excavation. Basic Construction has been doing site grading in the Tidewater area for about a century, and we have deep knowledge of the local soil composition and nuances. We have developed best practices that ensure our customers’ sites are built on stable ground today and maintain that composition for years to come. To arrange a consultation about your site grading project, contact Basic Construction today at (757) 249-3789.

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Topics: Contractors, Architects, Engineers