44 JULY 2025 WorldWide Drilling Resource® Selecting the Right Pump for Groundwater Sampling Adapted from Information by Royal Eijkelkamp Groundwater studies, particularly those focused on contamination, initiate with the process of sampling. The levels of groundwater can fluctuate significantly; in some areas, it may only be a few centimeters beneath the surface, while others, it can be several feet down. The depths of the groundwater plays a crucial role in selecting the appropriate pump or water sampler for the task. Furthermore, the decision regarding which groundwater pump to use is heavily influenced by the relevant sampling protocols and specific parameters being investigated in the study. Sampling Groundwater with a Suction Pump: For groundwater sampling at depths ranging from zero to about 26 feet below ground level, a peristaltic pump is an ideal choice. This type of pump is durable and well-suited for a variety of field conditions. One of its significant benefits is the water sample only comes into contact with the interior of the hoses, which are replaced after each sampling event. This practice greatly reduces the risk of sample contamination. Additionally, when the pump is not in operation, the flexible hose is fully compressed within the pump housing, preventing any backflow of water. Sampling Groundwater with a Submersible Pump: When groundwater is found at depths greater than 26 feet, a pump capable of pushing water upward is required. Generally, centrifugal pumps, also referred to as submersible pumps, are employed for this purpose. A centrifugal pump is typically connected to a hose and an electrical cable, and it is submerged below the groundwater level in a monitoring well. There are two types available: j Gigant and booster pumps are compact centrifugal submersible pumps that can fit into smaller sampling filters, although they do have a finite operational lifespan. A single gigant pump is capable of pushing water upwards, depending on the groundwater level. j Booster pumps can be utilized to enhance the system’s performance; by installing one, two, or up to three booster pumps directly above the gigant pump. To set this up, simply cut the hose and slide it under and over the connection nipple of the booster pump. The MP 1 submersible pump is designed for pumping and sampling wells with groundwater depths reaching up to approximately 300 feet. The pump’s motor, and consequently its flow rate, is managed by a continuously adjustable frequency converter, allowing for precise regulation of the pump’s output. The actual flow rate at any given frequency is influenced by groundwater levels; when high, the pump operates at a higher flow rate, while at very low groundwater levels, the flow rate at the same frequency may decrease. This versatility makes MP 1 pump ideal for rapidly pumping out the well and for collecting water samples at lower pumping speeds. Additionally, the MP 1 submersible pump consistently delivers a steady flow of nonaerated water. A simple pump that utilizes the push principle is the ball valve pump, capable of extracting water from depths of up to 164 feet, depending on the materials used and the surrounding conditions. To prevent contamination, it is essential to replace the hose during each sampling and to clean the stainless steel ball valve pump regularly. The ball valve pump comprises a hose with a stainless steel nonreturn valve at the bottom, equipped with a ball seal. When placed underwater, water flows into the hose up and down - new water is drawn into the hose while simultaneously pushing the existing water upward. This type of pump is lightweight, user-friendly, and quick to set up. However, it is crucial to ensure the ball valve remains submerged in the water column and does not rise above the groundwater level; air could mix with the sample water. Additionally, it is recommended to position the pump above the filter section of the monitoring well rather than at the filter level itself, as placing it at the filter level may lead to cloudy water samples. Gigant and booster pump. Ball valve pump. WTR
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