Understanding the Importance of Site Prep

Site Prep

In construction, the term site prep generally refers to the preliminary work of getting a construction site ready for building and development, following design. Encompassing a wide range of different preparatory activities including demolition, lot clearing, excavation, stabilization, and shoring, it is an important first step. It ensures a safe, properly constructed, stable foundation for your structure. Site prep is required whether you’re erecting an office building, sports stadium, water park or residential home. However, some projects may require more preparation than others.

What is involved?

Geotechnical Investigation/Soil Testing – Soils can vary in type, composition, and strength from one lot to the next. The differences can be quite significant. Some soils don’t possess the strength to stand up to construction while others are strong enough. Soil testing is conducted to discover these differences. After soil samples collected have been analyzed in a soils laboratory, a soils report is drafted, detailing or recommending any potential problems and what corrective actions are required to ensure sufficient foundational support. A few of these recommended actions are as follows:

  • Subgrade stabilization by lime treatment.
  • Subgrade stabilization by layers of geogrid.
  • Conditioning of the subgrade by scarification and recompaction to a specified depth.
  • Conditioning of the subgrade by deep over-excavation and recompaction to specified depth usually under buildings and structures. Occasionally this action could target specific footings.
  • Import, place, and compact a layer of non-expansive granular soil to a specified thickness, usually under buildings and structures.

A second phase of geotechnical/soil testing work is field testing. Field testing helps ensure the specifications, recommendations in the soils report, and design intent are met. Usually, the same geotechnical firm is hired to perform these services, but not always. These services also provide a third-party assurance to the owner/builder that the work is completed correctly; essentially providing a quality control (QC) testing service. A few of the QC testing services associated with site prep work include:

  • Moisture-Density Relationship (Proctor-density in the laboratory controlled test).
  • Field nuclear density and moisture test of soil worked as a final subgrade or foundation for the structure or building.
  • Moisture testing of soils as an interim check.

The excavation contractor and the QC testing firm coordinate in the field on a daily basis to verify the site prep is pass or fail. The results of all the field QC tests are also assembled in a final report at the end of the project.

Temporary Facilities, Connecting Water, Electricity, and Sewage – Oftentimes, before construction begins, it’s important to establish basic services to accommodate the working crews and visiting project stakeholders. A few such temporary services that may be needed from the project onset include:

  • Job trailers(s)
  • Temporary potable water
  • Temporary electricity hookup to public utility or a portable generator
  • Temporary sewer for job trailers
  • Port-a-johns/toilets
  • Water connection to city pipe or fire hydrant, or temporary pond for construction water
  • Water tower for construction water

Erosion and Sediment Control – The State of Arizona requires construction owners or general contractors to prepare a written plan, obtain a permit, and implement onsite/offsite measures to prevent significant erosion and manage sediment so it doesn’t leave the site; depending on project specifics. This state requirement is referred to as the Stormwater Pollution Prevention Plan (SWPPP) and all three of these elements should be implemented prior to site prep commencing.

Grading
Grading

Land clearing – In order to prepare for excavation and earthwork, the site must be cleared. Land clearing normally consists of the removal of trees (clear and grub), demolishing buildings and removing any existing underground infrastructure. Unknown structures or other obstacles that are a surprise to the project team may cause the construction process to run behind schedule and/or go over budget.

Pre-Wet
Pre-Wet

Pre-wet – After the land has been cleared, it is pre-wet or pre-soaked to mitigate dust during excavation, and in compliance with Maricopa County Dust Regulations (PM-10 Rules). The pre-wet also helps provide moisture control for site fills.

Excavation/Earthmoving – Excavation is the process of moving earth, rock and other materials using unique techniques, tools and equipment in order to create building foundations, reservoirs and roadways. Some of the different processes used in excavation include earthwork, structure excavation, cut-fill grading, trenching, digging, dredging, tunneling, and site development. Once a site has been cleared and its soil tested, the excavation process can begin. The process typically includes:

  • Setting out corner benchmarks.
  • Surveying ground and top levels.
  • Excavation to the approved depth.
  • Backfilling as needed.
  • Constructing wells and interconnecting trenches.
  • Making boundaries of the building.
  • Constructing protection bunds and drains.

Shoring – Occasionally, deep excavation or hillside excavations require us to utilize a shoring, or earth retention solution, such as installing soil nails to help render the excavation safe. Using soil nails is one of the most common and reliable methods for shoring. Excavation occurs in 5-foot to 6-foot lifts. Soil nails, such as hollow core or solid bar nails, are then installed into drilled holes with consistent horizontal and vertical spacing or pattern. Once this process is completed, the soil nails are grouted into the holes, and then a shotcrete facing is applied to the soil.

Expert Site Prep from Buesing Corp.

Buesing Corp. offers expert site prep and site development services for residential, commercial, and civil projects throughout the Southwest. We have a demonstrated history of providing our clients with superior excavation, material transport, site prep and site development, shoring, and drilling services regardless of project size. Our fleet of equipment includes excavators, loaders, backhoes, bulldozers, and motor graders. For more information on these or any other services, please visit us at www.buesingcorp.com or contact us at (602) 233-3339.

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