The knowledge of subsurface conditions including soil types, rock and water conditions is essential to proper site planning and design. Our Geotechnical technicians and engineers have extensive expertise to assist owners, developers, contractors and planners with understanding the sub-surface conditions that affect their site and project. Our knowledge and experience with all types of soils and rock formations allows us to provide concise and cost effective strategies and recommendations for building on the subsurface conditions encountered on a project site. Particularly in western North Carolina we are known for solving construction challenges on rock formations and unsuitable soils.
RETAINING WALL DESIGN
ALPHA can provide complete retaining wall design services on a wide variety of walls including segmental block, CMU, Cast-in-place, gabion and soldier pile walls. Our work includes full design services with drawings and specifications. We also provide contractor selection, construction oversite and testing, and final inspection with certification services.
SITE SUITABILITY EVALUATION
As part of our Geotechnical exploration, ALPHA provides detailed recommendations related to Commercial or Residential site condition and suitability for development. Typically we assess the soils, compaction, rock, groundwater and other important factors. In addition we will evaluate and provide project specific recommendations for pavements, building foundations and other site development installations for sewage, stormwater, surface drainage, and others.
Additionally, many counties and cities have established ordinances to regulate development in areas of steep slope. The ordinances require that the average natural slope be calculated on an area of interest based on vector contour lines. ALPHA can provide the slope certification either in conjunction with the above site evaluation or separately.
ALPHA will typically provide a seismic classification of a site it has drilled using the Standard Penetration Resistance (N value) determined from blow counts of the soils obtained at various drill depths. Seismic Site Classifications for a project site are utilized by the Architect/Engineering during structural design of project buildings.
ALPHA can also perform Seismic refraction surveys. The seismic refraction method utilizes the refraction of seismic waves on geologic layers and rock/soil units in order to characterize the subsurface geologic conditions and geologic structure. This method enables the general soil types and the approximate depth to strata boundaries, or to bedrock, to be determined.
SLOPE STABILITY ASSESSMENTS & CERTIFICATIONS
ALPHA provides geology and/or geotechnical engineering studies to slope failures or areas having the potential for slope failure.
A slopes’ soil is constantly moving downslope due to gravity. Movement can be either barely evident, noticed or devastatingly rapid. The slope angle, water, climate and slope material contribute to the movement. Water plays a major role in slope failure. Water can increase the driving force by filling previously empty pore spaces and fractures, adding to the total mass or weight of material that is on a slope.
Where integrity of the embankment is vital or in areas subject to detrimental hydraulic forces, additional embankment protection is often required. Stabilization can be achieved through slope reinforcement by constructing structural elements such as conventional piles or drilled shafts, soil nails through the failure plane. Surface covers or retaining walls are also used to improve a slopes’ stability.
DAM TESTING & SERVICES
ALPHA performs services and assists private owners of small and intermediate size dams in their Development of Emergency Action Plans (EAPs). These plans are mandatory and critical to reducing the risks of loss of life and property damage from dam failures. A Simplified inundation maps (SIMS) is developed by either employing simplified engineering assumptions and methods or by identifying potential at risk residences on photo-based mapping without engineering analysis. SIMS can either form the permanent basis of emergency and evacuation planning or be used for the interim until more detailed mapping is required.
Alpha Laboratory performs the full range of materials testing services in support of our Geotechnical Department. Testing of soils, rock and other materials for the determination of engineering properties are performed in accordance with the respective ASTM or AASHTO procedures relevant to each project requirements. See more detail in the Materials Laboratory Section under Construction Material Testing & Inspections.
SUB-SURFACE EXPLORATION OF SOILS (IN-SITU)
ALPHA employs an array of mechanically powered drilling platforms for subsurface explorations and in-situ (in-place) sampling of soils at a project site. Our capabilities include a large bore rig, an all-terrain track mounted rig, trailer rig, and small carrier rig for indoor and low clearance drilling. We typically perform drilling explorations in excess of 100 feet when required by the site conditions or project design use.
DYNAMIC CONE PENETROMETER (DCP) TESTING OF SOILS
ALPHA frequently utilizes Hand Auger Borings and DCP testing during evaluation of residential sites, for open building foundations, on steep slopes, and when a limited site exploration is all that’s needed.
TEST PIT OBSERVATION
ALPHA can provide observation of test pit excavations for a site preliminary evaluation or during site development. Test pits allow evaluation of the subsurface soil changes that assist in limited site planning recommendations without performing a full geotechnical exploration (drilling) of the project site, or to further investigate rock or other suspect conditions previously encountered at the site during construction.
FOUNDATION DESIGN SPECIFICATIONS
In conjunction with our sub-surface exploration ALPHA can provide swallow and deep foundation designs or recommendations to the project Architect/Engineer. These service can include extensive pile requirements, spread base footers, or soil repairs at isolated problem areas.
FOUNDATION FAILURE & REPAIR
Foundation damage and failure from expansive soils, settlement, frost, and other forces, can often look much worse than it actually is. And although it may appear that demolishing and rebuilding a foundation is inevitable, there are many design solutions that are often more cost effective. This is true for a residual home or commercial building.
ALPHA is experienced in inspecting foundations, determining the cause, and designing simple, permanent repair solutions, even for severely damaged foundations, without the need to rebuild.