WATERLOO - Model APS - Vertical Aquifer Profiling Tool
Lack of a sufficient understanding of the subsurface conditions often leads to underperforming remedies. Development of a valid Conceptual Site Model (CSM) is the single most important activity for ensuring that sound site management decisions, including remedy selection and design, are made.
High-resolution site characterization implemented with dynamic work strategies is the most cost effective way to develop the type of CSM necessary for successful, cost effective remedies. WATERLOOAPS™ is a complete direct push subsurface data collection platform, combining high-quality discrete sampling capability with continuous, real-time hydrosratigraphic logging. This system has been utilized worldwide for the past 25 years in a broad array of environments. Using hybrid drive methods, the WATERLOOAPS has achieved depths of 600 feet below ground surface.
The WATERLOOAPS was the first direct push injection logging tool and is combined with very high quality sample collection. This combination provides the ability to:
- Determine sampling depths in real-time based on hydraulic conductivity variations
- Determine the distribution of both hydraulic conductivity and contaminant concentrations in 3D with only one push per location
- Assess mass flux distributions and mass discharge using a single tool
The WATERLOOAPS collects very discrete samples due to:
- Short (2-inch) screened interval
- Small purge volumes
- Prevention of cross contamination or follow in the hole or tool
The WATERLOOAPS was originally designed and tested at the University of Waterloo by chemical hydrogeologists and is the only tool of its type to have been subjected to such scientific testing. Drag down, or cross contamination, is minimal in comparison to other tools. The profiler does not need to be tripped between samples and, due to its stainless steel sampling train, is free of sorption and desorption associated with tools using polymer tubing.
Real time hydrostratigraphic profiling in the same push with discrete depth sampling, without withdrawing the tool between samples, allows for very efficient high-resolution groundwater contamination investigation.
KPRO helps us select depths at which to collect samples based on changes in stratigraphy as opposed to random or predetermined “blind” intervals. The IK and sample collection are accomplished in a single push to obtain data more quickly and cost effectively.
It enables a better understanding of the site’s hydrostratigraphy for the creation of more accurate conceptual site models and flow and transport models.
It identifies impermeable zones so time is not wasted trying to collect water samples in suboptimal locations. Low permeability zones can, and should, be sampled using high-resolution soil sampling techniques. By sampling the interfaces of high and low K zones the WaterlooAPS data can identify where those aquitard materials are likely to contain contaminant mass and therefore should be targeted for detailed soil core profiling and analysis.
The KPRO system incorporated into the WATERLOOAPS is the original injection logging hydraulic profiling tool. As the tool is advanced, clean water is injected into the formation while depth, pressure, and flow rate are monitored. From these data, a real-time continuous log of the Index of Hydraulic Conductivity is calculated. It is not necessary to drive the tool once to log the hydrostratigraphy and again to sample—both are accomplished in a single push. Hydraulic head distributions can be determined if a common datum is established for the site and the ground surface elevation is known. In shallow water table conditions the depth to the potentiometric surface is measured using an uphole transducer. If the water table is deep (greater than the suction limit ~ 27 ft bgs) then a downhole transducer can be used to measure the pore pressure and converted to a hydraulic head.
WATERLOOAPS 225 A 2.25-inch OD version is the most robust model, built to be used with the Geoprobe 8040 rigs for maximal depth penetration. The tip has more open area for higher sampling rates and reduced clogging. The 225 can be used with either a peristaltic pump or with the downhole nitrogen drive positive displacement pump.
WATERLOOAPS 175 The 1.75-inch OD version is the same diameter as the original Waterloo Profiler but utilizes more durable direct push rod and has the unique APS tip design.
WATERLOOAPS 150 This small diameter version has an OD of 1.5-inches. Compared with the 175, the 150 is sometimes able to achieve better depth penetration due to the smaller diameter. In situations of limited access, the lighter and smaller 150 rods can be an advantage.
- The APS can be fitted with a Wenner array electrical conductivity logging tool to allow assessment of zones with high ionic strength pore fluids (brines, leachate etc). The EC log, in combination with the IK and the sampling capability, allow for very targeted and effective sampling in environments where high ionic strength pore fluids are of interest.