Borehole Geophysical Services Consultant; Wastewater Disposal Well Design and Construction; Geophysical Well Logging and Interpretation; Hydrogeological Characterization; Malcolm Park Wastewater Pump Station, Nassau, The Bahamas.

 A little background info

The objective of the project was to drill and construct a single wastewater disposal well for the new Malcolm Park Wastewater Pumping Station.

 Wellspring Consultants, Inc. was contracted by Island Site Development (ISD) to perform geophysical well logging and hydrological characterization of the wastewater disposal well. We also conducted video logging of the well at the property.The wastewater plant provides primary treatment for wastewater from the surrounding area. Screened effluent from the plant is to be injected in the wastewater well. The design flow for the plant and well is 1,750 igpm (2,100 gmp). In the future, the plant capacity may be expanded and wastewater pumped to a new Fox Hill wastewater treatment plant for further treatment. The current Malcolm Park site work includes the addition of a new building that will house the primary treatment equipment.

The ISD drilling crew obtained core and/or rock samples during the advancement of the well. The drillers log and samples were classified for lithology by a geologist in the field, with the lithologic classification incorporated into the data interpretations. 

Geophysical Services: What we did at the site 

Geophysical well logs measure physical and chemical properties of formations and fluids in or around the vicinity of the well. The result in a series of curves plotted on a graph showing changes in the properties with depth.

Geophysical well logging was performed utilizing the Gamma, Spontaneous Potential (SP) and Single-Point Resistance (SPR) Tool, the 3-Arm Caliper Tool, and Temperature and Fluid Resistivity Tools for data acquisition.   

We performed the well logging on the well to 520 feet BLS. Two runs were made with video logging equipment to the bottom of the well (590 feet BLS) to observe the formation and groundwater characteristics.   

The lithostratigraphy at the site, compiled from all the information gathered, consists of carbonate rocks down to a total depth of 590 feet below land surface. These include both porous and non-porous limestones and dolomite. The units are interbedded, with individual beds ranging in thickness up to 20 feet. Fractures, fissures, and cavities were also present. Generally, porous limestone is the predominant unit found in the lithostratigraphic column down to a depth of 295 feet BLS. The units consist of white to cream colored, tan to dark brown, fossiliferous limestone.  

Delivering Results

The formation below 400 feet BLS down to total depth appears to be conducive to the intended use of wastewater injection. The lithology of the rocks in this zone includes fractured limestone with fissures and cavities and dolomite replacement. The Malcomb Park Pumping Station is designed to provide primary wastewater treatment (screening) prior to conveying the wastewater to the injection well. The design capacity of the plant and well is 1,750 igpm (2,100 gpm).   

It appears that the well, when completed as specified, will be capable of receiving wastewater at its design capacity. That’s great news! This was a very interesting project.

Please contact us if we can be of assistance with any of your upcoming Geophysical Services or other project needs. Please take a look at our services page to see some of our other cornerstone projects.