Frequently Asked Questions
You have questions? We have answers!
What is an aquifer?
An aquifer is a sub-surface layer of water contained in unconsolidated material above the bedrock or in a layer in the bedrock itself. Aquifer water is a valuable source of drinking and process water around the globe. Great efforts are made to protect and preserve these water sources. So that is why groundwater monitoring and related equipment is a thing. Waterra Pumps is a specialist in ground water monitoring equipment.
What is a piezometer?
In the purest sense, it is a pressure measuring device or system. But, often the term is used in the groundwater business in reference to a test borehole used for scientific investigation of groundwater itself. Many people use piezometer and monitoring well interchangeably; as we do on this Waterra website. See “What is a monitoring well?”, directly below.
What is a monitoring well?
We generally use the term monitoring well on this Waterra website interchangeably with “piezometer.” It is used to reference a borehole drilled into an aquifer and completed for scientific investigation as described below.
Boreholes are drilled to access the water in the ground; ie the aquifer. Such wells are completed using a slotted pipe or screen in the aquifer interval and PVC pipe the rest of the way to surface. The annular gap outside of the pipe is filled with porous material in the aquifer zone to allow water into the piezometer (monitoring well). The rest of the annular gap outside of the borehole is sealed with some impermeable material such as bentonite clay to surface. This isolates the aquifer from surface drainage. Many of these wells are 2 inches (5cm) or less in diameter and require specific equipment to obtain samples and information. Waterra is a specialist in groundwater monitoring equipment.
What is low flow sampling?
Low flow sampling is a protocol of extracting groundwater from a monitoring well (piezometer) at a low flow rate. The general concept is to pump groundwater at the approximate natural flow rate within the aquifer. The idea is to not draw down the water table and hopefully minimize the disturbance to the natural flow regime. Another compelling reason to use low flow sampling is that there is much less purge water than that derived from the classic methodology of purging three well volumes. Less purge water means savings on containerization and disposal. The counterpoint is that the pumps need to be dedicated to the well and that cost can add up. A Waterra Submersible Pump or Waterra Peristaltic Pump may be useful to your program.
Pumping rates are usually 500 ml per minute or less. Many operators pump the water into a flow through cell which may have several probes that measure such parameters as temperature, turbidity, pH, dissolved oxygen, conductivity and oxidation-reduction potential. Operators look for stability in these parameters over time. When that is achieved, equilibrium is deemed to have been established between the aquifer water and the well water. A sample is then collected. Low flow sampling “standards” vary and should be tailored to the aquifer and monitoring well in question. Your regulator may have a lot to say in this regard.
Should I do low flow sampling?
That one is up to you, your project manager, client and/or regulator. We do not provide specifications on program protocols although we are familiar with many.
What pump is best for low flow sampling?
The short answer is, a pump that provides the desired low, continuous flow rate. Waterra Submersible Pumps are popular although in shallow applications, a Waterra Peristaltic Pump might find application. We would be happy to help you spec the right equipment for your application.
How much water should I purge from the monitoring well?
This question we turn around to you because your project manager, client and/or regulator may have established protocols in this regard. We are well aware that many people purge 3 well volumes prior to sampling. Low flow sampling protocols are very different. Bottom line, we are not the regulator so please do not rely on us for advice in this regard. We can however help you with equipment choices to meet your specifications.
How deep can I pump with a Waterra Pump?
The practical limit with current equipment is about 200 feet (60 m) and this would depend on the specifics of the situation. Let’s chat about it.
What Waterra Tubing size should I use?
This really boils down to what you are trying to accomplish in the field. Factors that affect your decision are type of pump, flow rate, depth of water table, well size, and other protocols imposed by the program. We are here to help sort it out.
Many monitoring wells are completed with 2″ Schedule 40 PVC and are less than 200 feet (60 m) in total depth. Waterra Pumps generally work very well in these circumstances. You will most likely want to use our Standard Flow System, that being a D-25 foot valve and Standard Tubing.
Should we use High Density Polyethylene Tubing (HDPE) or Low Density Polyethylene Tubing (LDPE)?
Depends! Don’t you hate those sorts of answers? Here are some factors to consider when choosing what type of Waterra Tubing.
Here’s for LDPE:
LDPE Tubing is somewhat more flexible than HDPE so, for instance, many submersible pump users like it because it is easier to plumb into the pump.
LDPE is less likely to develop a stress line and wear through if kinked.
LDPE tubing is often favored for use with the Waterra Pump in shallow monitoring wells, up to a maximum depth of about 60 to 70 feet.Beyond this depth HDPE tubing is recommended.
Here’s for HDPE:
HDPE Tubing is slightly more inert than LDPE.
HDPE is less elastic and in deep wells, especially if you are using the Waterra Pump High Flow System. Stiffer is better so one doesn’t lose stroke in stretching and un-stretching the tubing.
Sometimes it boils down to availability of one type versus the other. LDPE and HDPE costs are the same.
What is the maximum lift of a Waterra Peristaltic Pump?
Theoretically, about 33.9 feet (10.3 m) at sea level but more realistically about 27 feet (8.2m) is the maximum lift at sea level. The higher your altitude, the less the lift because there is less atmospheric pressure “pushing“ the water up the column.
How long will a Waterra Spectra Field-Pro run on one charge?
A new fully charged Field-Pro should run for about 8 hours under full load.
The Field Pro is equipped with a 12 Amp-hour, 12 volt AGM battery and smart charger. This battery is designed to be cycled between 13.5 volts (full charge) and 11.5 volts (discharged). If the battery is cycled between these voltage values, the battery may last for as many as 2000 cycles. Discharging the battery below 11.5 volts will cause damage to the battery by reducing its storage capacity. Discharging the battery to a voltage state below 9 volts may reduce the cycle life of the battery significantly, possibly to less than 50 cycles. If the battery voltage is below 6 volts, the smart charger will not charge the battery.
How clean are Waterra Filters?
Waterra Filters are manufactured under strict quality control conditions in our specialized clean room with HEPA filters and a controlled air supply. One litre of de-ionized water is flowed through every single filter to pick up any available metal ions. We then dry the filters with pure clean room air. Our operators wear cleanroom suits including gloves and hairnets. Check out this cleanroom photo.And to prove this all works, we sample one out of every hundred filters produced. We send this test filter to a lab to make sure there are no metals in the filters. Every lot sold has a test result of Non-Detect for all the metals tested. That’s law at Waterra. So, the answer is: VERY CLEAN!
What Waterra Filter size should I use?
Well, let’s be clear with what you mean by size; Filter Pore Size or the Surface Area of filter media? Groundwater filters are usually 0.45 micron pore size. Check in with your project manager or regulator to be sure what your protocol should be. Note, we carry filters with 0.1 micron, 0.22 micron, 0.45 micron, 1.0 micron and 5 micron pore sizes.
Regarding surface area, we carry 300 square centimeter filters and 600 square centimeter filters which carry the CAP300 and CAP600 designations respectively.
Usually for 0.45 micron groundwater filtering, if you have clear water and/or require only a small sample you might choose the less expensive 300 square centimeter Filter Medium Turbidity – FMT. For bigger volumes or very turbid water, a 600 square centimeter Filter High Turbidity – FHT might be a better choice.
Why is the Waterra HS2 Oil-Water Interface Sensor ultrasonic technology better than other oil-water sensors?
When we were designing the HS2, we knew that many users became frustrated with the existing technology because of what we call the “goo” factor. Degrading hydrocarbons can get gooey and stick on the optical sensors used by other manufacturers. Also, those plastic light sensors can get scratched and misbehave accordingly. Our quest was to transcend the goo factor and have a long term reliable instrument.
Here’s how we did it. We send an ultrasonic signal across a gap in the sensor. If there is liquid, of any type, filling the gap, the sensor then checks to see if the liquid is conductive (water) or non- conductive (hydrocarbon). The instrument indicator lights and buzzer let you know if you are in a liquid and what type of liquid it is: water or hydrocarbon.
Ultrasonics are superior because they ”see through” a thin layer of goo and “examine” the full gap between sensors. An optical system isn’t that smart. Furthermore, the sharp conductivity pin in the sensor gap clears of hydrocarbon and goo very quickly. Even if there is a little bit of goo hanging around our sensor is not incapacitated by it like the optical systems are. We have a sensing protocol that helps establish the product layer very precisely. See our “Waterra oil-water interface sensor animation” near the bottom of this linked page.
Is Kynar coated well tape better than Polyethylene coated well tape?
Kynar coated Waterra well tape is certainly is tougher than Polyethylene coated well tape but it does cost more. Having said that, we are talking plastic coatings here not armored steel. So a sharp edge on the well casing or dropping something sharp and or heavy on an exposed tape in the back of truck or on a shop floor is still a risk. Treat your Waterra WS Water Level Sensor and Waterra HS2 Oil-Water Interface Sensor like an instrument and you will get many years of use from it.
Kynar is a fluorocarbon (PVDF) so if PFOA or PFAS are concerns at your site, you may want to use a polyethylene tape.
How much will shipping cost?
That’s a tough one, unless we know where you are, what’s being shipped and how fast you want it. But we can figure it out if we know the answers to those questions. If you provide a credit card, UPS or FEDEX account number we can ship it on your account. That way you’ll know we didn’t mark it up. If you pick it up from our facility, we won’t send you a bill for shipping (special orders excepted) or if you visit one of our distributors you probably won’t get a shipping bill from them either.