1600 Specht Point Road    Suite 209    Fort Collins, CO 80525    Ph 970.488.3111    Fax 970.488.3112      

 


GEOTECHNICAL ENGINEERING

The following are representative projects performed by personnel of Engineering Analytics, Inc.

 


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EA provides management consulting and technical services in four principal business areas:

  

 

BUILDING DISTRESS DUE TO EXPANSIVE SOILS

  


EA staff performed geotechnical investigations to evaluate distress at the TRACON building, located at Denver International Airport. The building has experienced significant movement at the slab-on-grade floor and piers since construction. The following services were provided to develop opinions about the cause of distress to the building and to aid in determining areas of movement and the safety of the building:

  • Subsurface exploration and sampling

  • Installation of piezometers and moisture access tubes

  • Installations of deep bench marks to assist in movement monitoring of the building

  • Laboratory testing

  • Calculations of maximum future heave and time rate of heave

  • Water source and migration studies

  • Evaluation of feasibility of dewatering system

  • Coordination of remediation plans and costs

  • Identification of design and construction deficiencies

  • Preparation of geotechnical investigation reports

The results of our investigation indicated that the major cause of distress to the TRACON building is the movement of the slab-on-grade floor resulting from heaving soils and bedrock. Our investigation also showed that movement of the piers is a major concern. Our time rate of heave analyses showed that the additional heave that will occur in the next 10 years may increase distress above a critical level at the TRACON building.

Our water migration study concluded that the TRACON building has three major sources of water to the subsoils. Conceptual remediation plans proposed elimination of the potential water sources to the site.
 

 


 Photo of Buckled Partition Wall Stud,
TRACON Building, Denver, Colorado
Photo of Dry Wall Crack, TRACON Building, Denver, Colorado

 

FOUNDATION MOVEMENT DUE TO EXPANSIVE SOILS

  
 


EA staff performed an investigation of the heave induced stress at Woodward Governor’s 200,000 square foot manufacturing facility in Loveland, Colorado. The building has experienced movement of the piers and structural floors from heaving of soil and bedrock. EA staff provided the following services to develop opinions about the cause of distress to the building and to determine the magnitude of total and future heave:

  • Subsurface Exploration and Sampling

  • Laboratory Testing

  • Groundwater Level Monitoring

  • Calculations of Free-Field Heave and Pier Heave

  • Preparations of a Geotechnical Investigation Report

The investigation and analyses showed the piers were being affected by deep-seated swelling soils and that the piers should be anticipated to experience a total heave of 10 to 15 inches. Differential pier movement has caused large lateral forces to be applied to the piers, and caused many of the piers to experience shear failure. The differential movement also caused cosmetic distress to the building.

The pathways of water flow to and through the foundation bedrock are of particular interest due to the relatively great depths at which heave appears to be occurring. The analyses of groundwater indicate that the primary pathways for surface water to the foundation bedrock are through the pervious backfill placed adjacent to the basement walls and through open bedding planes, joints and fractures in the bedrock.
 



Photo of Pier Shear Failure, Woodward Governor Building, Loveland, Colorado

 

 
 

URANIUM MINE & MILL SITE RECLAMATION AND CLOSURE PLAN

 
 


EA staff provided consulting services to Umetco Minerals Corporation for reclamation of their uranium mine and mill site at Gas Hills, Wyoming. The project consisted of design for reclamation of an inactive tailings impoundment, two mine ore excavations and two evaporation ponds. EA staff also performed a site-wide hydrology study, a characterization study of the groundwater and geochemistry and a risk assessment analysis for clean-up of radiological contaminants.
 

Consulting Services Provided:

  • Analyses of the existing cover system on the inactive tailings impoundment and design of an enhanced cover to provide adequate erosion protection for the 1,000-year design life

  • Cover design for the two mine ore excavations and two evaporation ponds including geotechnical stability analyses, settlement analyses, radon attenuation analyses, infiltration analyses and erosion protection design

  • Characterization of subsurface flow conditions and contaminant transport mechanisms

  • Groundwater characterization and preliminary assessment of remedial action alternatives

  • Radiological investigation and risk assessment to evaluate potential radiological risk to the public and to evaluate the feasibility of remedial action alternatives
     



Reclamation of Uranium Mine and Mill Site,
Gas Hills, Wyoming

 

SPRING VALLEY LANDSLIDE

  
 


The Spring Valley landslide is located on the North Fork of Cache Creek downstream from the Indian Valley Dam and upstream from the residential community of Spring Valley in Lake County, California. The study was contracted by the U.S. Army Corps of Engineers and Lake County Emergency Services to determine the potential of a landslide failure and creation of a landslide dam across the North Fork of Cache Creek.

EA staff’s investigation concluded that an intense precipitation even such as a 100-year, 10-day storm would induce failure in the landslide within 6 days. Failure of the landslide could result in a dam across the North Fork of Cache Creek up to 191 feet in height. The Corps of Engineering determined that if a wet winter season occurred in conjunction with a 100-year 10-day storm, the Indian Valley Reservoir would have no storage available for storm water and reservoir releases would be required. These releases would be sufficient to fill the landslide reservoir within 10 to 14 days, overtop and subsequently breach the landslide dam. EA ISG performed a breach analysis for the landslide dam scenarios using the National Weather Service Dam Breach Program. The computed breach outflow hydrograph was routed downstream using the two-dimensional flood routing program FLO-2D.

EA provided several alternatives for an emergency response plan in the event of a landslide dam. It was determined that the most practical approach would be post-landslide mitigation that would involve excavating a ‘spillway’ trench through the landslide.

 


Client: U.S. Army Corps of Engineers/Lake County, California, Emergency Services 

 

 


 

 
 

TAILINGS DAM IMPROVEMENT AND RECLAMATION PLAN

  
 


EA staff designed and supervised construction of a reclamation plan and embankment raise for Umetco Minerals Corporation’s tailings dam in Hot Springs, Arkansas. The goal was to design a reclamation plan that provided for continued operation while improving the existing drainage system and overall stability of the impoundment. Design controls included maintaining the existing toe of the embankment while excavating the downstream face of the dam to a 3:1 slope, and constructing an upsteam raise from the excavated materials. EA staff provided QA/QC through completion of the project.
 

EA staff provided the following services:

  • Preliminary subsurface investigation, including a comprehensive sampling program and piezometer installation

  • Flood routing and design of two spillways to control basin and impoundment runoff

  • Seepage analyses for design of a blanket drain to control the phreatic surface

  • Embankment stability analyses for static and seismic conditions

  • Liquefaction analyses

  • Construction specifications and construction oversight

 

 


Hot Springs Tailings Dam, Arkansas

Client: Umetco Minerals Corporation
 

ROADWAY ANALYSES AND STABILIZATION PLANS

  
 


EA investigated distress to the roadways of a large private housing development in Colorado Springs, Colorado. A majority of the distress was determined to be from settlement of soils due to inadequate construction and inadequate compaction of fill soils. Additionally, the development had 23 active landslides on the site and two of the landslides were causing major distress to the roadways.

EA staff investigated and analyzed the settlement of the roadways and the two landslides. The investigation included geologic mapping, review of aerial photographs, excavation of borings and laboratory testing. The borings were instrumented with piezometers and slope inclinometers and movement has been recorded over the last several years.

EA staff prepared plans and specifications for repair of nine areas. Construction was performed in 2002/2003 to repair seven of these nine areas.

Additionally, EA prepared plans and specifications for instrumenting one of the landslides to provide real-time monitoring of movement to allow warning of future landslide movement. The monitoring system was constructed in July 2003. EA staff provided geotechnical QA/QC during construction of these projects.

 

 


 Roadway Distress, Colorado Springs,
Colorado
 

DISTRESS TO RESIDENTIAL STRUCTURES DUE TO EXPANSIVE SOILS

  

 

 

EA staff performed geotechnical investigations of approximately 40 residences at the Powderhorn subdivision to evaluate causes of distress to the structure. The basements of the houses had either structural wood floors or slab-on-grade floors. All of the structures had either pier foundations or spread pad foundations that rested on over-excavated fill material.

The subdivision is located within the steeply dipping bedrock area. Sites on steeply dipping bedrock show greater amounts of differential heave and a much higher frequency of damage than sites on horizontally bedded bedrock. Therefore, the construction of the houses on the steeply dipping bedrock posed a particular danger over conditions that would be encountered at other sites.

EA staff provided the following services to develop opinions about the cause of distress to the structures and to aid in determining areas of movement:

  • Review of original soil reports and construction plan

  • Subsurface exploration and sampling

  • Laboratory testing

  • Prediction of pier or spread footing heave

  • Analyses of pressure exerted on the basement walls by expansive backfill

  • Identification of design and construction deficiencies

  • Preparation of geotechnical investigation reports

EA’s work has had a significant impact on the legal procedures associated with these residences. Also, the work conducted by EA has formed a basis for publications that have advanced the state-of-the-art in heave prediction and has significantly improved the state-of-the-practices.

 



Photo of Pavement Distress,
Littleton, Colorado



Photo of Wood Frame Failure,
Littleton, Colorado

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  Engineering Analytics, Inc.
1600 Specht Point Road, Suite 209
Fort Collins, Colorado 80525
Phone: (970) 488-3111
Fax: (970) 488-3112

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