Welcome to Lourie Consultants' collection of in-house technical articles, presentations, and newsletters. Our goal is to share technical information that is interesting and valuable to our clients in a brief, easy to read format.
PROFESSIONAL LIABILITY ISSUES RELATED TO GEOTECHNICAL ENGINEERING
DEVELOPING BROWNFIELDS -- ENVIRONMENTAL CONSIDERATIONS
DEVELOPING BROWNFIELDS -- GEOTECHNICAL CONSIDERATIONS
In increasing numbers, public and private owners are seeking alternatives to the traditional approach to project delivery. The traditional approach provides for the owner to select and contract for design services. There is a separate contract for construction services. While allowing the design professional to maintain independent professional judgment, the traditional approach, nonetheless, includes a separate contract for design services.
What is driving this search for alternative project delivery systems? Quite simply, project owners are seeking more cost-effective solutions, higher quality products and services, shorter project schedules, and fewer legal entanglements on their projects. Project owners also want design firms that give more attention to project constructability. Various methods have been developed in recent years to assist in team building and risk sharing to ease delivery of projects. The most popular alternatives to traditional project systems are outlined below.
In a Design-Build delivery system, the owner retains a single entity that provides both the design and construction services for the project. The Design-Build Contractor becomes the single point of responsibility for the project. The Design-Build contractor is a vendor to the owner. The subcontractors to the Design-Build contractor are in the same vendor relationship with the owner. Theoretically, Design-Build provides for lower total project costs based on more rapid delivery time and the ability of the architect/engineer (A/E) and contractor to work towards containing costs. Design-Build can foster innovative design solutions as the A/E and contractor pursue a common goal within the design-build process. Value engineering is an implicit part of the process.
A thorough project description is needed before selecting a Design-Build contractor. The project description must include performance specifications in the scope of work package, particularly for projects involving building or systems construction. Considerable effort and expense goes into producing a Design-Build Request for Proposal (RFP) package. Inherently however, there are differences in cultures between engineering firms and contractors which could result in problems in delivery of the project.
A major disadvantage to Design-Build is that only certain types of projects are suited for Design-Build. Ideal building projects are those that can be well defined by the user organization during the bidding and negotiations stage. However, Design-Build should not be used to obtain low-cost professional design services nor should it be used to limit the involvement of design professionals. Numerous public and private owners have found that quality design services and adequate workscopes lead to significantly lower construction and life-cycle costs. Projects such as full-services remediation do not work well as Design-Build. These projects have workscopes which include investigations and studies to define the extent of contamination and are therefore difficult to bid and execute as Design-Build.
Federal government agencies increasingly use Design-Build delivery systems. The General Services Administration (GSA), U.S. Postal Service (USPS), and the State Department are making significant use of Design-Build as a project delivery system. At the USPS, Design-Build delivery systems accounted for 19 percent of procurement in 1992. The Environmental Protection Agency (EPA) contracts nearly all of its work using nontraditional project delivery systems.
Construction management (CM) is defined as maximizing an owner's capital investment through the coordinated efforts of the designer, owner, and construction contractors working together to preserve and enhance the quality of the project, control construction costs and time, and to reduce long-term operating and maintenance costs. The construction management program objectives are achieved by exercising good management practices. Selecting a construction manager's services is done using a qualifications-based selection (QBS) approach just as one would select a design professional for conceptual and detailed services. This selection method helps provide a good match between the owner's needs and the CM's capabilities, skills, and experience. Construction Management is useful particularly when the owner does not have experience with construction and wants to hire an expert to represent the owner's interest. The CM can bring the entire project team together during the design phase to develop the most cost-efficient project meeting the client's needs. One disadvantage to CM as a project delivery system is final costs are not guaranteed unless the CM agrees to a guaranteed maximum price after the schematic design documents are available. As the owner assumes the responsibility of selecting the CM, the project can suffer if the owner selects the wrong CM for the job. Under many public statutes, the CM is precluded from performing work with its own forces.
Agency Construction Management and independent contractor CM have been used successfully for many years for projects involving building construction. Many owners prefer these project delivery systems to advance projects rapidly from conceptual design to finished, constructed product. Full-service environmental design firms are increasingly undertaking the CM's role in remediation projects. The trend toward full-service remediation is driven by environmental remediation projects which are complex and generally not understood by the owners. These projects also need professional services throughout the project to alter the design to conform to actual conditions encountered during construction. Generally, remediation projects also require detailed documentation of field activities and interaction with regulatory agencies which can be provided by the CM. Construction management can be an important project delivery system to complete environmental remediation projects cost effectively and on time.
Privatization is a variety of techniques and activities to promote more involvement of the private sector in providing traditional government or public services. Privatization is not one or a limited set of techniques but is a number of management techniques to affect delivery of a project. Some advantages of privatization include capital cost savings to the public, shorter implementation time, and the ability to procure services or projects otherwise unavailable in the public sector. Constraints to privatization include the need for legislation to allow privatization and political opposition to the privatization concept. Another constraint is the potential for labor problems from public employees unions, and from public employees themselves if public sector jobs are eliminated as a result of privatization.
Partnering is not a project delivery system, but is a way to conduct business among the team members. In the partnering approach, the owner, contractor, and design professional develop an agreement before construction based on the mutual trust among the parties. Generally, the partnering agreement is the culmination of a preconstruction workshop led by an independent facilitator. Key elements of partnering include Commitment, Equity, Trust, Mutual Goals Development, Timely Responsiveness, Implementation, and Continuous Evaluation. Private-sector partnering and public-sector partnering can have different aspects. In the private-sector arrangement, long-term relationships can be established among the owner, A/E, and/or construction firm. In the public sector, the partnering arrangement generally begins after the award of the contract, and includes the owner, design professionals, and contractor. Both the public and private sectors partnering agreements have the common thread of increased productivity, cost-effectiveness, and continuous quality improvement of services and products.
A single-story grocery store in south-central Louisiana with steel frame construction and brick and masonry block exterior walls. Maximum loads are 70 kips for the columns and 4 kips/lin ft for the walls. The structure is supported on a shallow foundation and has a uniform thickness slab-on-grade floor system.
In 1984, about 1 yr after construction was finished, the owner and building occupant saw building distress on the interior and exterior of the structure. More specifically, the exterior walls on the building's north and east side developed cracks and the interior floor slab became uneven. The parties initially involved with the project suspected either foundation settlement or soil shrinkage was the cause of the distress. The building's tenant had concerns about the structural integrity of the building and the safety issues associated with uneven flooring. Survey data later showed that upward movements caused by soil expansion caused the distress.
In June 1982, an owner/developer retained a local geotechnical firm to perform an investigation for the project. The work consisted of 11 undisturbed-sample borings and four auger borings. The undisturbed-sample boring extended to depths of 16 to 30 ft while the auger borings extended to 6-ft depth. The undisturbed-sample borings were advanced to between 16- and 20-ft depth using dry-auger techniques; wet-rotary methods were used below the dry-auger depth. Water was encountered at about 18-ft penetration in only one of the open boreholes.
At the time of the study, site grade varied between about El 25 and 40 ft Mean Sea Level (MSL). The site was covered with grass, brush, and trees. The trees (gum, pecan, elm, and oak) had trunk diameters ranging between about 12 and 24 inches.
The firm's evaluation and recommendations can be summarized as follows:
The owner/developer elected to use shallow foundations placed in the Stratum II or III soils and a uniform thickness slab-on-grade floor system. The existing trees were removed, and the ground surface in the building area was lowered about 3 to 4 ft so that the ground surface was at about El 34. The owner/developer also retained the geotechnical firm to provide construction materials testing (CMT) services.
Construction began in January 1983 and it was finished in the fall of 1983. The firm's CMT services consisted of conducting soil density tests and observing foundation excavations prior to concrete placement. From January to April 1983, the firm made 13 site visits. All the earthwork and footing installations were completed within this time.
The author became involved with the project in April 1985 to assess the problem, identify possible causes and potential solutions, and to represent the owner/developer in the event of litigation. At that time, visual observations indicated that movements had occurred that resulted in cracks in the exterior brick and masonry block walls. Crack widths varied from hairline to as wide as 0.5 to 0.75 inch. On the interior of the store, floor tiles were loose and cracked and there was distortion of the floor board molding and wall covering. Some dampness was observed under some of the floor tiles. This portion of the store contained refrigerated vegetable coolers with water misters. Utility lines below the floor slab consisted of water supply lines, drain lines, and a garbage disposal line.
To assess the problem, a series of steps were undertaken. These steps included:
Soil Properties. The regional geology consists of soils belonging to the Prairie Formation, a Pleistocene age terrace deposit. Typically, these soils are overconsolidated, strong clays. Some of these soils are low plasticity clays while others are highly plastic.
At the site, the Stratum II and III soils had liquid limits (LLs) that ranged from 32 to 95 percent and averaged 56 percent. The average plasticity index (PI) was 33 percent and individual PIs ranged between 6 and 69 percent. The average plastic limit (PL) was 23 percent. The natural moisture content (Wc) of these soils at the time of the initial geotechnical study varied between 14 and 42 percent and averaged 24 percent. The investigative post-construction testing showed some increases in Wc, on the order of 2 to 3 percentage points. The shallow soil's undrained soil shear strength (Su) was between about 1.3 and 4.6 ksf and it was typically about 1.5 to 2 ksf. The unit dry weight (UDW) of these soils was usually between about 90 and 95 pcf; however, some samples had UDWs of 105 to 110 pcf.
Clay Mineralogy. X-ray diffraction tests performed as part of the investigation showed that a sample from about El 30 contained 42 percent smectite, 22 percent illite, and 36 percent kaolinite. This sample had a LL of 46 percent and a PI of 28 percent.
Swell Potential. The clay mineralogy information and swell test data combined with the previously described Wc, plasticity, UDW, and Su data suggested these soils had a high to very high swell potential if soil moisture contents were allowed to increase.
Survey Data. Movement data collected in May 1986 showed the east wall had experienced about 2 in. of upward vertical movement; the north wall had about 0.8 in. of upward vertical movement and some outward movement to the north; and the floor slab heaved about 3 in. in some areas. Heave plots and contours showed the upward movements were concentrated over a buried utility line trench.
Groundwater Data. Test pits, shallow borings, and open piezometers installed to various depths were located along the exterior of the structure. The test pits showed water seeping out from below the footings that were about 2 to 2.5 ft below grade. The piezometers showed static, long-term groundwater levels were below about El 26 or about 8 ft below the finish floor elevation. However, several shallow piezometers along the east side of the structure showed a water surface at about El 31.
Source of Water. To determine possible sources of water, the owner/developer conducted an extensive testing program. This work consisted of using pressure tests and fluorescein dye to test all known drain, supply, and sewer lines. Vent-to-roof lines were tested with water. Chemical analyses were performed on water samples collected from the test pits and piezometers and the results were compared to the contents of the drain, supply, and sewer lines. These tests were inconclusive in that no leaks were identified and the chemical analyses did not clearly identify the source of the water.
The investigative work clearly indicated that soil heaving of the potentially expansive clays was occurring. Soil moisture contents had increased and water was seeping out from below the shallow footings. However, the water source could not be positively identified. While the movement rate had slowed considerably, the owner/developer still had a dissatisfied tenant. Since slight movements greatly reduce swell pressures and some soil moisture content increases had occurred, the decision was made to begin making building repairs.
Repair Scheme. In general, the repair concept required breaking out the existing concrete floor on the building's interior and rebuilding portions of the north and east exterior walls. All this had to be performed while the store remained open for business.
Observations. During the floor slab breakout and removal operations, soil moisture content tests were performed in various areas. In one of the utility trench lines, unusually high moisture contents were measured. This trench contained a water line that supplied water used to mist produce and for other purposes. Further observations and investigation revealed that water was leaking from a slab-level fitting on this valve. Although the line had been tested, the valve only leaked when it was open. When the valve was closed (as it was during pressure testing), no leakage occurred. Finally, the source of water had been identified! The repair work proceeded and it was completed in late 1986. Since then, no additional problems have developed and the structure is performing according to the tenant's and owner/developer's expectations. No litigation occurred.
Out-of Pocket Repair Costs. The owner/developer incurred substantial costs to investigate and repair the problem. The out-of-pocket costs were about $160,000.
The lessons learned from this case history can be somewhat difficult to identify. However, there seem to be lessons for design professionals as well as for owners and developers. Some of these are:
An independent chemical laboratory can be an invaluable project asset. It can provide unbiased, third-party data, handle work overloads for in-house laboratories, and offer services not found within a company or government agency. Increased regulatory compliance since the mid-1980s created the need for laboratories to provide more than analytical services. Today, there are many environmental laboratories to choose from, which complicates the process. And, if many laboratories fit the description above, how do you select the laboratory that is right for your needs? Below are some guidelines for streamlining the selection process.
Insist On Quality. This should be your foremost consideration when choosing a laboratory. The laboratory should provide quality data to meet your needs. The core of an environmental laboratory is its quality assurance/quality control (QA/QC) program. Ask to see it. Also ask about the laboratory's system for tracking samples and results. Study the laboratory's Mission Statement.
Search For Experience. The best asbestos laboratory in the country may be inadequate to handle the testing from your hazardous waste project. Be sure the laboratory has experienced personnel in your area of interest. Does the laboratory have enough personnel to handle your project needs? Ask for client references.
The Value Of Local Presence. If your project needs involve regulatory compliance, is the laboratory familiar with the agency having jurisdiction over your project? It may be helpful to select a local laboratory if your project involves regional environmental mandates that have no federal counterpart.
What About Certification? There is not a universally accepted certification program now in place for laboratories. Be cautious of a laboratory's use of words like 'approved' and 'recognized'. Determine the requirements to obtain such status.
Visit The Facility. Visiting the laboratory and meeting the people who will test your samples will help your selection process. It will give you the opportunity to audit laboratory practices and to see how your samples will be handled. Ask to review a typical report for clarity and readability. This is especially helpful if nontechnical managers will receive the data. Can you get data in a client-specified electronic format?
Conduct A Performance Evaluation. Before making a final selection, send the laboratory some samples for testing. The samples should be uniform; with known constituents and concentrations in them.
Cost. The cost of an analysis is a function of the laboratory's commitment to quality. The cost for analysis among qualified laboratories should not vary considerably. Significant variations in the cost of an analysis are due to methodology differences. If you find differences in cost between laboratories, ask each laboratory to describe its method to you. Make sure you have specified all aspects of your project needs before selecting the laboratory with the lowest price.