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"Bringing analytical knowledge into the field where hydrogeologic, hydrologic and environmental problems need to be solved."
HYDROLOGIC SERVICES
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Sample Project - Pratt Museum
The Pratt Museum in Homer, Alaska contracted Coble Geophysical Services for a stream rehabilitation project as part plans for the new museum. The local Woodard Creek had been channeled into a culvert for decades and paved over. The effort beside the new museum would daylight the stream again to provide a unique urban riparian area with trails.
CGS hydrologic services include collection of field data to support regulatory reports, drafting required plans for regulators of development projects, providing erosion protection plans, as well as measurements and modeling of sediment transport.
Discharge measurement equipment includes non-mechanical Marsh-McKbirney flow meters with datalogging capability, precipitation and weather parameter monitoring, botanical and soils field analyses including unsaturated parameters of soils using tensiometers. Free surface flow modeling is used to determine discharge rates through culverts, and data from NOAA is used to assess hydrologic capacities and flood risks in specific watersheds.
CGS provides these parameters as required in regulatory reports for a variety of clients including USCG, Institutions, Engineering Firms and General Contractors. Examples include SWPPP’s required by ADEC, Water Diversion Plans required by ADNR Dam Safety, Dewatering Plans required by ADEC/EPA and Wetlands Mapping Reports required by USACE.
CGS has also been contracted to study and intensively monitor surface water turbidity in remote locations, and perform gravel sediment transport and sediment transport studies, and provide coastal and river/stream restoration and erosion protection plans and recommendations.
First a detailed map of the hydrogeology of the area was constructed through monitoring wells installed by CGS using Discovery Drilling.
Hydrologic Services
The culvert gradient was relatively steep, requiring drop structures in the design area. Therefore, existing drop structures were monitored on Woodard Creed during routine surface water discharge monitoring for sediment transport and erosion potential. The design data included historical discharge data to determine design flow rates for the replacement channel.
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The positions and drop heights of the drop structures are shown here comparing the replacement streambed to the existing culvert.
Options for post-vegetation of this stretch of Woodard Creek were then provided to the Pratt Museum Building Committee (Coble Geophysical Services – Conrad Field, Low Elevation Southcentral Region, 10/29/13). Specific details for each vegetation component were selected by Conrad Field (Alaska botanical expert), such as this recommendation for hydrologic and aesthetic application at a drop structure: ‘Devils Club - Benefits: beautiful foliage and berries, moose-proof, good on steep slopes established by rock such as adjacent to constructed drop structures, providing a natural barrier for surface water drop structure; Drawbacks: needs open area and sun, for example under a tall spruce canopy’