Arrange for Dakota to probe your site with our self-contained direct push technology (DPT) systems, or hire an outside DPT contractor. Dakota will need to communicate with your potential contractor to determine if they are capable of pushing direct sensing equipment. We have integrated with most Geoprobe models, many AMS probe machines, Marl rigs, homemade probe machines, CME drill rigs, mini CPT skids, tracked CPT machines, and several brands of 40 ton CPT trucks.
Dakota personnel have been instructed NOT TO PROCEED until public and private underground utilities have been identified. Please communicate with Dakota to ensure that this is completed.
If any special security, permits, or safety clearance is needed for Dakota’s personnel or equipment, alert Dakota prior to us arriving on-site.
The main components of the HRSC systems are housed in a shock-protected enclosure measuring roughly 2 x 2 x 2 feet and weighing approximately 100 pounds. In addition to this enclosure, there is a computer, fiber cables, a generator, tools, spare probes, and various peripheral items. When we ship the system, everything typically fits in a 4 x 4 x 4 foot enclosed pallet. A fork lift and secure storage should be arranged near the work site.
Some customers like to pre-plan the hole locations, mark the site accordingly, and record all relevant x-y and elevation data. A plan of bounding the contamination based on results determined on-site is also viable. Regardless if the hole placement follows a grid or bounding procedure, Dakota strongly prefers to start LIF projects in what is believed to be the heart of the contamination. This gives everyone involved valuable information regarding how well the NAPL is going to respond to LIF delineation.
Dakota recommends discrete sampling at 10% of the hole locations if correlative samples are desired or required. If an extensive sampling program is planned, the client should consider including a local driller and/or a second rig. Remember to build sampling time into your scope of work. If Dakota is contracted to collect soil samples, it will be prudent to do all the sampling at one time, preferably as the final stage of the field activities. More information about confirmation sampling is provided under the Investigation Process section for each technology on our website.
UVOST and TarGOST productivity can range anywhere from 200 to over 500 ft/day, while DyeLIF is slightly less. MIP and HPT production is typically in the range of 200 to 250 ft/day. If the pushes are fairly deep (>30 ft), and the obstructions or rubble are minimal, then the average is on the higher end because we spend a lot more time actually probing, not moving around from location to location and/or trying multiple times to get holes started through rubble. Other factors affecting production are grouting requirements, surface pavement, surface topography, and vegetation.
When the system first arrives on site, it is powered up, and tested for proper function. Different HRSC technologies have different set-up and start-up requirements. More information about start-up and set-up procedures and time requirements is provided under the Investigation Process section for each technology on our website.
Typically Dakota uses a rubber rod wiper to “squeegee” any contaminated mud from the probe. If additional decontamination is required, production rates will be impacted accordingly.
LIF operations on a barge usually limit daily production to 50 to 200 feet of logged depth. Additional factors affecting barge productivity are; location accuracy needed, subsurface conditions, water depth, and presence of current or tide.
Electrical Conductivity (EC)
Dakota's Electrical Conductivity (EC) measurement is an additional service provided during the HRSC investigation. The EC system operates at the same time direct sensing data are being gathered. Different soil types will conduct electricity differently depending on particle size and mineralogy. For example, clays generally will have high conductivity while gravels will have low conductivity. By logging EC with the other direct sensing data, the user can develop a site wide model of source pollution and unconsolidated stratigraphy, which are two key components to predicting mobility.
Electrical Conductivity Features:
- Reports EC in milli-Siemens per meter (mS/m) units
- Log and plot EC with other Dakota data from the same software package
- Compatible with moderate percussion delivery
Once a log is completed, our HRSC operators can immediately generate an image of the log. For LIF projects, callouts are used to show the waveform from areas of interest. Along with the %RE versus depth plot, the scatter, and the fluorescence levels as a function of depth are provided. Secondary data such as the rate of probe advancement, the amount of hammering required to advance the probe with percussion systems, and conductivity may also be available. At the bottom of the log is the pertinent info for the data such as site name and location as well as basic stats such as total depth. These images can be printed on site.
Data in Text and Raw Binary Format
Along with the log image, our customers are given the data in ASCII tab delimited format. Customers will also receive the raw binary data format that may be viewed using our OST Software.
Dakota prides itself on going the extra mile for our customers. Whether it is providing detailed information, or walking the customer through the data on the phone long after we have left the site. We are committed to our customers being well informed and pleased with our service.
Once Dakota leaves, our customers may wish to survey all the HRSC locations if it wasn’t done prior to the project. Getting good positional information, including elevation, is key to any future CAD and visualization efforts.
Additional Services Available
Conceptual Site Model Visualization Option
Dakota now provides the capability to view HRSC data in unparalleled resolution. With our 3D models, the client has full control of the camera and is not limited by viewing static images.
Advanced Data Analysis Using NNLS Option
Many natural geologic materials fluoresce. In order to effectively interpret LIF logs, we sometimes need to separate NAPL fluorescence from false positives such as peat, meadow mat, algae, crushed limestone, wood, and shell hash. Non-negative least squares (NNLS) analysis provides an effective solution.
Written Report Option
Dakota can summarize all on-site activity as well as provide detailed log and waveform analysis in the form of a written report.