Biotechnical Services

Abstract The Bonnet Carre' Spillway diverts water from the Mississippi River through a floodway into brackish Lake Pontchartrain to reduce river stages at New Orleans and prevent flood damage. Pallid Sturgeon Scaphirhynchus albus, a federally listed species under the Endangered Species Act, and Shovelnose Sturgeon Scaphirhynchus platorynchus, listed under the Similarity of Appearance rule, are entrained through the spillway structure and become trapped in the canals and shallow lakes. The two species of sturgeon were identified according to a suite of morphomeristic characters, not genetically, and were therefore noted as either Shovelnose Sturgeon or presumed Pallid Sturgeon. Rescue efforts were undertaken to return the entrained sturgeon back into the Mississippi River. This article describes the environmental and operational conditions that influence entrainment risk, catch, and potential impacts on the population. Five openings and corresponding rescue operations occurred between 2008 and 2019 after each spillway closure. A total of 70 days with a crew number ranging from 6 to 12 were expended to collect 57 Pallid Sturgeon, four of which were dead, and 362 Shovelnose Sturgeon, 83 of which were dead, after the five openings that spanned 240 total days. More sturgeon were entrained at higher water temperatures, with a greater number of bays opened for longer durations. Recovery of sturgeon is initially high but over time declines as sturgeon are depleted from the floodway, stranded in isolated waterbodies in the floodway, and/or displaced further downstream into Lake Pontchartrain during longer openings. Sturgeon that cannot find their way back to the floodway are unlikely to be rescued. Recent population studies indicate that only a small proportion of the Lower Mississippi River total population is entrained. However, this does not take into account those individuals entrained but not captured and the potential impacts if more frequent openings of the structure were to continue in the future. Conservation recommendations are provided to increase catch efficiency and recovery of the endangered sturgeon.

Recently in the Lehigh Valley, PA, a 2.5-million square-foot distribution complex in karstic terrain was built in less than one year, thanks in part to the efficient use of multiple geo-techniques during design and construction. A combination of geophysics, karst mapping, and conventional geotechnical intrusive testing was used to characterize the undulating 200-acre agricultural site. Geophysical methods included the use of ground penetrating radar and two-dimensional resistivity to assess the consistency of the subsurface profile, and to map the top-of-rock profile and karst-related anomalies. This enabled the intrusive geotechnical exploration to strategically target areas where geophysical anomalies were detected, and to reduce the overall scope of the geotechnical program. Due to the challenging fine-grained soils, winter conditions, and a compressed schedule, the site development incorporated various techniques to permit construction to proceed, including lime stabilization; cement stabilization of the floor slab subgrades; optimization of heavy-duty asphalt pavements; as well as sinkhole stabilization.

Excessive erosion was observed within the slopes of a 1.3 km long earth embankment supporting an active roadway. The embankment extends up to 15 m above the bottom of an adjacent river. The slopes exceed 1 horizontal to 1 vertical (1 Hz: 1Vl) in some locations and are mostly covered with vegetation. Airborne LiDAR technologies were used to capture the existing topography and generate a digital terrain map which was used to determine changes in elevation and calculate the degree of steepness. The subsurface soils consist of high quantities of silts indicating a high susceptibility to erosion. The current embankment health was assessed by evaluating the stability of the slopes using surface and subsurface information. Several mitigation schemes were developed to increase the health of the embankment and protect the existing roadway. The selected scheme considered multiple aspects including surface drainage, constructability, and cost.

BackgroundPropofol is a widely used injectable anesthetic agent for induction and short-term maintenance in dogs. A multi-dose formulation of propofol (MDP) has been developed which includes 2% benzyl alcohol as a preservative. In order to document the use of the product under clinical conditions, MDP was tested in a prospective clinical trial conducted at six sites within the United States. One hundred thirty-eight healthy, client-owned dogs were assigned to one of six treatment groups based on premedicants (none, acepromazine/buprenorphine, midazolam/buprenorphine, medetomidine/buprenorphine) and maintenance agents (MDP, inhaled anesthetic). Anesthesia was induced by the intravenous administration of MDP given to effect. Physiological indices including heart rate, respiratory rate and blood pressure were monitored prior to and during anesthesia induction, maintenance and recovery. Adverse events, defined for severity by pre-established limits of these physiological values, as well as side effects, defined as any observation outside the normal range, were noted.ResultsThe mean intubation dose was 7.6 ± 2.1 mg/kg for MDP alone and 4.7 ± 1.3, 4.0 ± 1.0 mg/kg and 3.2 ± 1.4 mg/kg when buprenorphine was used in combination with midazolam, acepromazine and medetomidine, respectively. Of the 32 adverse events, apnea (12 incidents), bradycardia (9 incidents) and hypotension (7 incidents) were most frequently recorded. Emesis, cyanosis and second degree heart block were each noted once and successfully resolved. The cause of a single death 2 days post-anesthesia was assessed as a surgical complication.ConclusionsMDP was found to be acceptable for use in healthy dogs for induction and short term maintenance of anesthesia when used alone and in combination with premedicants and inhaled anesthetics.

This paper covers the design of levee section LPV 111, part of the New Orleans flood protection system. The Deep Mixing Method (DMM) was used to stabilize the soft organic soils below the levee to increase global stability and reduce settlements such that the levee could be built to meet design requirements within a compressed schedule. The design was based on a DMM strength of 690 kN/m2, which was achievable in the soft organic clays. Spoil material generated by the DMM process was incorporated into the levee fill after testing showed that it provided a high quality fill material. This reduced the amount of imported fill required by about 400,000 m3. As part of the Corps of Engineers' Early Contractor Involvement (ECI) process, the contractor provided input to optimize the design based on the contractor's experience, tooling, and equipment. This paper documents the design constraints, methods of analysis, subsurface conditions prior to construction, and properties of the deep mixed ground.

The Portland cement manufacturing process produces considerable amount of cement kiln dust (CKD). While many facilities are able to reuse a significant portion of CKD in their production lines, a large percentage is removed as industrial waste and placed in landfills. Because of the large amount of material potentially available for use, and in an effort to cut disposal costs, alternative and beneficial uses for CKD need to be investigated. This study presents experimental results of the use of CKD in modification and stabilization of soils from the Aberdeen and Everett areas in the state of Washington. These soils are typically wet of the optimum water content and pose problems during geotechnical construction. CKD was added in percentages of 5, 10, 15, and 20% by dry weight of the soils. Laboratory tests, including drying rate of the soils, Atterberg limits, standard proctor and unconfined compressive strength were conducted. Results of the investigation showed significant improvement in drying rate and unconfined compressive strength of the CKD treated specimens as the percentage of CKD increased. It was also found that lower percentages of CKD can be used for modification purposes, whereas higher percentages of CKD can be used for both modification and stabilization purposes in geotechnical construction.

The construction of new Limestone Unloading and Reclaim Structures, and associated conveyor tunnels, required excavation and retention of over 12m (40-ft) of fly ash and fill material. The presence of a high ground water table and a relatively thin layer of soil below the excavation also provided for challenging geotechnical conditions to be overcome by the design/build team. A traditional rectangular excavation with a perimeter consisting of soldier piles and lagging or sheet piles would require several levels of significant interior wales and struts which would interfere with excavation and construction of the new structures. Ground and site conditions dictated that tieback installation would be costly. To accommodate the requirement to provide a cost effective dry and unrestricted deep excavation, the design/build team opted to build a pair of circular cofferdams, incorporating cast-in-place concrete compression rings to provide the required lateral support. This paper presents the innovative design and construction techniques that were successfully implemented during the project, resulting in significant savings in cost and time over conventional excavation support methods.

The construction of the Water Intake Structure for a new Cooling Tower at a power plant required excavation of a 16.76m (55-ft) deep pit beside the Susquehanna River south of Harrisburg, PA. The grading for the excavation was confined by a lined fly ash landfill on one side, an unlined fly ash waste area on another and the outlet channel from the existing operating power plant on a third. With top of rock being little more than 1.52m (5-ft) beneath the normal pool in the outlet channel, and rises in pool level in the Susquehanna River expected to be as much as 5.5m (18-ft) during construction, the site presented challenging conditions to be overcome by the design/build team. In addition to providing a description of the different ground support structures used in this project, this paper will focus on the innovative design and construction techniques implemented to construct the river wall in the dry, maintain a water-tight barrier, and provide for unfettered wall removal and channel restoration.

Cross-hole sonic logging (CSL) has become an important, nondestructive testing (NDT) method used in evaluating the integrity of foundation structures to maintain quality assurance and quality control (QA/QC) of transportation facilities and infrastructures. Tomography, based on three-dimensional cross-hole sonic logging data processing technology, offers an improvement over the techniques currently used to characterize the interior structure of drilled shafts. The underlying concept for seismic tomography is based on the principle that acoustic waves propagate at different velocities through different types of material or the same material with different physical properties. Three-dimensional velocity tomographic images provide greater detail of the interior structure, making defects easier to classify with respect to size and location within the foundation structure. By classifying these defects, an engineer has the information necessary to better assess whether these structures meet the applicable design requirements, allowing them to repair or replace inadequate foundation structures. The end result is that the foundation structures will be more likely to meet the safety and service life requirements for their project. Applications of seismic tomography will be presented, illustrating how seismic imaging can provide a reasonable estimate regarding the integrity of foundation structures.