Hydrologic Investigations

Summary of Expertise

  • Surface Water Characterization
  • Groundwater Characterization
  • Assessment of Impacts
  • Design of Mitigation Measures

What are the local surface and groundwater resources?   Will my project impact those resources?  Am I about to build on a floodplain?  EarthFax has assisted several clients in answering these and other hydrologic questions.  Our experience has included:

DESIGN OF HYDRAULIC STRUCTURES.  EarthFax has designed hydraulic structures throughout Utah and other western States as well as internationally.  These designs have included multiple runoff- and sediment-control structures, including culverts, open channels, sedimentation basins, channel-stability improvements, sediment traps, and other structures.  We have designed these structures for a wide variety of environments, from lowland ephemeral gullies cut into unconsolidated silt and clay to high-elevation perennial streams cut into bedrock and boulders.  In addition to water-conveyance structures, the vast majority of these projects have required that we design energy dissipators to ensure that erosion downstream from the structure would be precluded.  We have also designed fish baffles to be installed in culverts placed in perennial streams, thereby minimizing the environmental impacts of the installation.  We have developed cost estimates for installing and removing numerous hydraulic structures, and have prepared detailed plans and specifications as part of bid packages.  We have also provided construction inspection to ensure that our designs are properly implemented.  Some of our work has received national and international acclaim.  In 2002, one of our projects was designated as a Best Practice by the Eurasian-American Partnership for Environmentally Sustainable Economies.  This project, which included the design of hydraulic structures (including open channels and sedimentation basins), represented work that we completed at a coal mine in the Russian Far East to minimize environmental impacts and maximize coal recovery from a large waste-rock pile. Our work was so designated because it demonstrated "environmentally sound and economically efficient solutions to environmental problems in Central and Eastern Europe and Asia."  In 2003, another one of our projects received the Excellence in Surface Coal Mining and Reclamation National Award, presented by the U.S. Department of Interior, Office of Surface Mining to our client, Castle Gate Holding Company. EarthFax designed reclamation topography and hydraulic structures and provided construction quality control services on this project, which was completed at underground coal mining operations in east-central Utah.ÿ The award was presented "for outstanding performance in developing and implementing exemplary mining and reclamation methods that maintained sound environmental conditions."

HYDRAULIC DESIGN ASSOCIATED WITH A BOX CULVERT BENEATH I-70.  An EarthFax client was developing a pozzolan mine in Sevier County, Utah and needed to convey the ore across Interstate 70 for processing.  Rather than incur the cost and safety hazards of trucking this ore, the decision was made to transport the material in an enclosed conveyor that would be installed along the top of an existing box culvert that carried ephemeral runoff beneath the freeway.  EarthFax evaluated the hydraulic capacity of the box culvert without the conveyor and, in consultation with the client and UDOT, determined that additional freeboard would be needed during the design runoff event.  As a result, we designed a detention pond upstream from the box culvert to reduce the peak flow entering the culvert from both the 100-year, 24-hour storm and the 500-year, 24-hour storm to ensure that the depth of storm water flow through the culvert box would leave a freeboard of at least 2.5 feet and 1.5 feet, respectively.  The detention pond includes a sediment settling basin to prevent sediment and debris from accumulating in the culvert box.  The pond was sited in the vicinity of an existing borrow pit created during the construction of I-70 and will reduce disturbed land areas created as a result of the project.  Flow through the culvert during the design storm events will occupy approximately 33% and 50 % of the capacity of the culvert, respectively, assuming that the elevation of the bottom of the enclosed conveyor is the highest elevation available for flow through the culvert.  This factor of safety will ensure that anticipated flows through the culvert will not adversely affect the integrity of the highway or threaten the functionality of the conveyor.

DESIGN OF STREAM CROSSINGS FOR A PETROLEUM PIPELINE EXPANSION. EarthFax evaluated stream-crossing locations along the route of a proposed crude-oil pipeline that that was to be constructed for approximately 90 miles from Evanston, Wyoming to Salt Lake City, Utah.  The stream crossings were to occur within the Weber River and its tributaries.  Based on our observations, we considered various alternatives for installation of the new pipeline across the streams to minimize damage.  These alternatives included spanning, boring, and trenching.  We prepared stream-alteration permits for submittal by the client to the U.S. Army Corps of Engineers and the Utah State Engineer?s Office.ÿ EarthFax provided typical design drawings and specifications as well as construction alternatives for completing the stream channel crossings.ÿ In one location, EarthFax prepared a plan to repair a portion of Lost Creek where a failed beaver dam had caused significant erosion on private land.  In another location, we designed a hydraulic structure to carry irrigation return flow in a non-erosive manner from a large field to the adjacent stream.  In each of these instances, we collected site-specific survey data, evaluated design discharge rates, designed open channels and erosion-protection features, and provided the client with documentation that was used for construction bidding.

PERENNIAL STREAM SURVEYS ASSOCIATED WITH PROPOSED COAL MINE EXPANSION. EarthFax conducted perennial stream surveys in an area overlying an underground coal mine in central Utah to establish baseline data in preparation for opening a new lease at the mine. This information would allow a future evaluation of the potential affects of mining on the hydrologic system. To accomplish this task, we identified the beginning of perennial flow in the main canyons and their tributaries and mapped stream channel profiles using both hand-held and more accurate backpack-mounted GPS receivers. Data collected in the field were transferred to 7.5 minute USGS topographic maps and included in the report to the client.

HYDROGEOLOGIC ASSESSMENT AT A HAZARDOUS WASTE TRANSFER, STORAGE, AND DISPOSAL FACILITY. EarthFax performed a geotechnical and hydrogeologic assessment to determine general subsurface conditions in a two square mile area of Utah’s West Desert. This work was performed to assist the client in evaluating this area as an alternative site for locating a hazardous waste treatment, storage, and disposal facility. The scope of the project included assessing existing chemical conditions of soil and groundwater, potential soil and water pathways for future contamination should it occur, the potential for on-site remediation if contamination should occur, and general geotechnical conditions including the extent of subsurface clays. To accomplish this scope, we drilled 10 borings to a depth of 50 feet to define the underlying stratigraphy, collecting split-spoon samples being collected on 5-foot intervals and submitting those samples for laboratory analyses of geotechnical and chemical properties. We installed three 4-inch diameter monitor wells and sampled those wells for a variety of organic, inorganic, and radiologic parameters. Baseline soil sampling was conducted at ten locations by advancing shallow hand dug pits, then further advancing a one-foot hole to extract a channel sample. Data gathered were analyzed and provided the basis for a discussion of soil engineering, physical, and chemical properties in addition to groundwater quality.

INFLUENCE OF THE PROPOSED DISCHARGE OF COOLING WATER BLOWDOWN ON HYDROGEOLOGIC CONDITIONS AT AN INCINERATION FACILITY. EarthFax evaluated hydrogeologic conditions at a hazardous waste incineration facility as they relate to the proposed discharge of cooling water blowdown onto the ground. This evaluation included a review of data previously collected in the area from adjacent deep water-supply wells and information about the chemical quality of blowdown water. Calculations were made to determine the absorptive capabilities of underlying site soils and evaporation rates of surface water in the area relative to the estimated annual discharge of the blowdown water. The possible chemical effect of blowdown water percolating to the water table was also evaluated.

HYDROLOGIC AND GEOMORPHIC EVALUATIONS ASSOCIATED WITH MINE WATER DISCHARGE. EarthFax conducted an evaluation of the effects, if any, of a substantial increase in mine water discharged to mountainous streams from an underground coal mine in central Utah. The increased quantity of mine water resulted from exposure of a fractured channel sandstone at the working face of the mine. This discharge water eventually reached a major mountain reservoir that had been classified by the State as a cold-water fishery that had been “impaired” by historic activities in the area due to elevated levels of phosphorus and low levels of dissolved oxygen. Our work included performing hydrologic and geomorphic evaluations of the stream channels to assess the structural and erosional stability of the channel beds and banks, assess the effects of mine-water discharges on peak annual flows, determine the impacts of increased mine-water discharges on man-made structures in the creeks, and evaluate methods to protect the streams. Field work undertaken to accomplish these tasks included surveying stream channel cross sections, collecting flow measurements, and collecting soil samples from the stream beds and banks. The structural stability of the channel banks was evaluated using slope-stability software. The erosional stability of the stream beds and banks was determined using an allowable-velocity approach and stream geomorphic evaluations. The results of our evaluation indicated that the stream banks and floodplains were generally stable at the evaluated reference reaches. An exception occurred on a section of privately-owned land that is over grazed, making it prone to erosion during peak flow events. Man-made structures were determined to be unaffected by the increased mine-water discharge. Recommendations included maintaining the mine-water discharge point at its current location, periodically surveying the creeks to ensure that long-term impacts are minimized, and maintaining a water-quality monitoring program in the streams.
 
HYDROLOGIC INVESTIGATIONS AT A URANIUM MILL. Groundwater conditions were investigated by EarthFax at an existing uranium mill in southeastern Utah to aid in the development of a remedial-action program to control groundwater contamination at the site.  Fracture systems were identified using very-low-frequency electromagnetic geophysical methods, following which long-term pumping tests were conducted to define the anisotropic nature of the contaminated aquifer.   Seepage rates from the tailings ponds were determined and the fractured aquifer was modeled to determine the rate and direction of groundwater and contaminant movement at the site.  Flood-control plans were also developed to comply with regulations promulgated by the U.S. Nuclear Regulatory Commission for both the operational and post-reclamation periods. 

HYDROLOGIC BASELINE CHARACTERIZATION OF COAL MINES. Existing hydrologic conditions were determined at several surface and underground coal mines in the western United States. These projects have included the collection of site-specific field data to evaluate existing hydrologic conditions and the probable impacts of mining on the hydrologic regime.  Several monitoring wells and stream-gaging stations were installed for the collection of water-quantity and -quality data.  Utilizing the site-specific and regional data, existing conditions were established and the future hydrologic consequences of mining were projected. Reports were prepared for submission to state and federal regulatory agencies to satisfy permitting requirements.

DETERMINATION OF MINE DEWATERING IMPACTS. A rich ore body of lead, zinc, and silver was proposed for mining in an area that would require mine dewatering. The water to be encountered was hot (approximately 130° C) and saline (with a total dissolved solids concentration of about 7000 milligrams per liter). Previous dewatering operations in the region had pumped water to percolation ponds on an alluvial fan that was situated above a valley that relied on groundwater for irrigation. Investigations were performed to determine the potential of future dewatering operations to impact the valley's groundwater resources. Data from local water-supply wells were reviewed to determine whether or not past impacts had occurred. Alternatives for mine-water disposal were evaluated. A monitoring program was designed to assess future impacts. Liaison was provided between the mining company, regulatory agencies, and legal counsel.

HYDROGEOLOGIC ASSESSMENT FOR A GAS STORAGE RESERVOIR
. A hydrogeologic assessment was conducted to assist in the design of a groundwater monitoring system to be installed at a proposed natural gas storage reservoir in Michigan. Water well records were collected and extensively reviewed to delineate the horizontal and vertical extent of the potentially-impacted aquifer, the direction of groundwater flow, geology, and water quality adjacent to each of the proposed injection/withdrawal wells to comply with State regulations. Based on information collected during the hydrogeologic study, a conceptual groundwater monitoring system was designed for long-term observations and sampling.

MISCELLANEOUS MINING HYDROLOGY SERVICES
. Miscellaneous mining hydrology services were provided for a large international  mineral mining company. Services included:

  • Review of the technical adequacy of ongoing groundwater and geothermal modeling efforts required for development of a dewatering plan for a proposed surface gold mining operation in Papua New Guinea.
  • Evaluation of baseline hydrologic data, preparation of mine permit documentation, and determination of mine dewatering requirements for a proposed underground uranium mine and associated mill in Wyoming.
  • Performance of pumping tests, evaluation of the resulting data, and performance of a groundwater modeling investigation to assist in the development of a dewatering plan for an existing surface gold mine in Utah.

MEANDER CORRIDOR IMPACT EVALUATION AND MITIGATION PLAN. Meander corridor impact evaluations and mitigation plans have been prepared for development companies with property adjacent to a major river in northern Utah. The purpose of the evaluations was to respond to county concerns regarding protection of the established river channel meander corridor, and to protect the client's property from erosion during a 100-year peak flood event. Existing records were reviewed to determine the nature of the soils and flood-flow conditions at the sites. Cross sections of the stream channel and flood plain were surveyed to estimate flow depths within the channel and across the floodplain during the design event. Based on the development designs proposed for the properties, mitigation plans were recommended to protect the sites from flood erosion and to comply with county requirements to protect the established meander corridor.

DESIGN OF CHANNEL STABILIZATION MEASURES IN KANSAS.  Construction of a crude-oil pipeline created instability in the bank and bed of a stream in northeastern Kansas.  This instability resulted in exposure of approximately 25 feet of an adjacent crude-oil pipeline that had been previously installed in the same right-of-way.  The exposed pipeline extended perpendicularly into the stream channel, significantly increasing the potential for damage from debris carried by the stream during frequent flooding events.  Furthermore, extensive erosion of the stream bank had resulted in deposition of a substantial volume of sediment in the stream channel both up- and downstream from the exposure, significantly reducing the hydraulic capacity of the stream.  EarthFax evaluated conditions in the immediate area of concern as well as up- and downstream from that area, performed land surveys, prepared drawings and other documents to detail the design, assisted the client in obtaining stream alteration permits, and reviewed construction information to help the client with project implementation.  Our mitigation design consisted of the following measures: 

  • Install compacted backfill around the exposed pipeline, covering the pipeline with a minimum of 24 inches of compacted soil.
  •  Install filter fabric over the compacted backfill.
  • Install riprap over the filter fabric, creating a jetty where the pipeline extends into the channel.  This riprap was keyed into the undisturbed ground and blended into the slope to avoid an abrupt change in the face of the channel bank.
  • Remove large debris from the channel immediately upstream from the exposure to improve the hydraulic efficiency of the channel and avoid the potential for this debris to damage the jetty.
  • Remove accumulated sediment from the stream channel to improve its hydraulic efficiency.
  • Install gabions where the channel bank had been eroded to a near-vertical condition, thereby providing long-term stability to the bank in this area.

Before and After stabilization

 

 

DESIGN OF CHANNEL STABILIZATION MEASURES IN MISSOURI.  Installation of a new crude-oil pipeline created stream channel instability within the right-of-way of an existing pipeline in northwestern Missouri.  Backwater from flooding of the nearby Missouri River weakened the channel, causing it to slough and expose unwrapped pipe at the end of a span.  The channel instability also created a risk for collapse of an in-stream structure that was supporting the span.  Furthermore, improper use of erosion-control fabric below bank-full stage at the location of the new pipeline cause mass wasting of the stream bank at that location.  Material that sloughed from the bank created a restriction in the stream channel upstream from the pipeline, causing erosion of the opposite bank.  EarthFax evaluated site conditions and developed the following mitigation plan: 

·         Remove sloughed soil that was restricting the channel and threatening further failure.

·         Install a French drain in the sloughed bank to move water away from the bank when it saturates in the future.

·         Install riprap on both banks to protect against erosion and increase stability by weighting the toe of each bank.

·         Remove the ineffective erosion-control fabric, regrade the area, and revegetate with a local seed mix. 

DESIGN OF CHANNEL STABILIZATION MEASURES IN LOUISANA.  The stream bank adjacent to a 16-inch diameter petroleum pipeline began eroding toward the pipeline in the late 1980s.  To protect their asset, the pipeline company installed approximately 430 feet of sheet piling in 1989 as a retaining wall in the stream bank.  This sheet piling was secured to timber pile with steel tie-back cables, with the ground surface behind the sheet piling being about 25 feet above the stream channel.  In late 2011, approximately 90 feet of this sheet piling failed, causing the piling to bulge out over the creek from a hinge line at about the same elevation as the bottom of the creek.  The pipeline company installed additional timber piles and tie-back cables to pull the sheet piling back to its original orientation.  In mid-2013, the sheet piling failed again, bending at the earlier hinge line.  EarthFax was tasked with evaluating the cause of the failure and developing alternatives to provide a long-term solution for stabilizing the stream bank at this location.  We determined that a primary cause of the failure was the build-up of hydrostatic pressure behind the retaining wall, without a mechanism in place to relive that pressure.  Based on these observations, we presented the following mitigation options to the client: 

  • Remove the damaged sheet piling and replace the failed section of the retaining wall with additional sheet piling and tie-back cables.  Install a drainage layer behind the retaining wall to relive pressure from this area in the future.
  • Remove the damaged sheet piling and replace the failed section of the retaining wall with a reinforced soil retaining wall that includes a drainage layer.
  • Remove the damaged sheet piling, reroute the pipeline, lay back the channel bank, and armor the slope with vegetated riprap or articulated concrete that does not require an additional drainage layer. 

The client elected to replace the damaged sheet piling with a sloped embankment armored with articulated concrete.  EarthFax prepared design drawings with specifications for the project. 

DESIGN OF CHANNEL STABILIZATION MEASURES IN UTAH.  Flooding from snowmelt runoff in the spring of 2011 caused the Weber River in northern Utah to jump out of its normal channel and flow down what had been a small overflow channel adjacent to an island in the middle of the river.  This overflow channel previously conveyed