Choosing groundwater sampling equipment based only on purchase price can create unexpected problems during actual field operations.
In one recent groundwater sampling project, a municipal testing department purchased a conventional groundwater sampler because of a limited budget. However, during sampling from a 120-meter-deep monitoring well, the team encountered serious problems: well purging took more than four hours, groundwater samples experienced severe volatilization, and the test data repeatedly failed review.
After repeated sampling failures, the project team contacted AIMOLI to evaluate the AML918 Groundwater Sampling System as an alternative solution.
This case explains what happened, why the original sampling method created problems, and how the AML918 is designed to improve groundwater purging, sampling efficiency and quality control.
Project Background
Engineer Wang from a municipal testing department originally contacted AIMOLI because his team needed to purchase a groundwater sampler for an urgent project.
The project had a limited procurement budget, and the purchase also needed to go through a third-party procurement process.
At that time, AIMOLI recommended the AML918 Groundwater Sampling System and explained some of the limitations that can occur with conventional groundwater sampling equipment.
However, because of the price difference, the project team ultimately selected another traditional groundwater sampler.
Several months later, the situation changed.
The equipment they had purchased did not perform as expected during actual field sampling, so Engineer Wang contacted AIMOLI again and planned to visit the factory before making another procurement decision.
What Went Wrong During Groundwater Sampling?
The problems became clear during sampling from a 120-meter-deep groundwater monitoring well.
The project team reported three major difficulties.
1. Well Purging Took More Than Four Hours
The well-purging process took more than four hours for a single well.
For a project involving multiple monitoring wells, this level of field time can significantly affect the overall project schedule.
Long purging times can also increase labor requirements and make groundwater sampling operations more difficult to manage.
2. Groundwater Samples Experienced Severe Volatilization
The collected groundwater samples experienced significant volatilization.
This was particularly concerning because the samples needed to pass laboratory review.
When sample integrity is affected during collection or handling, the resulting analytical data may not accurately represent the groundwater conditions at the monitoring well.
3. Test Data Repeatedly Failed Review
The sampling problems were not limited to field efficiency.
The test data repeatedly failed review, forcing the team to repeat the work.
This created a chain reaction:
Sampling problem → Data review failure → Repeated sampling → Project delay → Increased labor and equipment costs
The repeated failures eventually caused significant pressure on the project team and led them to reconsider the original equipment selection.
Why Traditional Groundwater Sampling Can Be Difficult
Traditional groundwater sampling methods often depend heavily on the operator’s experience and manual control.
During sampling operations, technicians may need to manually adjust the flow rate, continuously monitor the well-purging process and determine whether groundwater conditions have reached the required state.
This creates several potential challenges:
- Long field operation times
- High dependence on operator experience
- Difficult flow-rate control
- Difficult water-level management
- Increased risk of sampling disturbance
- Greater workload for field technicians
- Potential inconsistency between different operators
For deep monitoring wells, these challenges can become more significant because the amount of groundwater that must be purged may be substantial.
Two Common Problems With Traditional Bailer Sampling
Traditional bailer sampling is still used in some groundwater sampling applications, but it can create practical challenges when large-volume well purging or controlled sampling is required.
Problem 1: Long Sampling Time and Low Efficiency
Before collecting a representative groundwater sample, the monitoring well generally needs to be purged according to the applicable sampling procedure.
Depending on the applicable standard and project requirements, well purging may continue until groundwater quality parameters stabilize or until the required volume of stagnant water has been removed.
Simply lowering and retrieving a small number of bailer samples does not necessarily provide an efficient solution for this process.
For deep wells, the amount of water that needs to be removed can make the process particularly time-consuming.
Problem 2: Difficult Sampling Quality Control
Traditional bailer operation also requires careful manual handling.
The bailer needs to be lowered and retrieved slowly and gently to minimize unnecessary disturbance to the groundwater.
This can be physically demanding for operators, particularly when working with deep monitoring wells.
The quality of the final sample can therefore be influenced by:
- Operator experience
- Lifting speed
- Lowering speed
- Sampling depth
- Well conditions
- Purging procedure
- Sample handling
For professional groundwater monitoring projects, reducing unnecessary dependence on manual operation can help improve consistency.
AML918 Groundwater Sampling System: One Pump for Two Functions
To address these problems, AIMOLI developed the AML918 Groundwater Sampling System.
One of the main design features of AML918 is that one pump can perform two functions:
High Flow — Well Purging
The system can operate at a higher flow rate during well purging to improve field efficiency.
Low Flow — Groundwater Sampling
The same pump can then operate at a lower flow rate during sample collection.
This allows the operator to use one integrated system for both:
Well Purging → Groundwater Sampling
rather than relying on separate equipment for different stages of the operation.
According to the manufacturer’s product information, AML918 is designed for applications complying with HJ1019-2019 and HJ164-2020.
Users should always follow the current version of the applicable standard and the specific requirements of their project.
Automatic Water-Level Drawdown Control
Another important feature of AML918 is its dedicated water-level drawdown control unit.
During groundwater sampling, excessive drawdown can affect sampling conditions.
AML918 is designed to monitor the water level during operation.
When the water level drops by more than 10 cm, the system automatically pauses the purging process and resumes operation after the water level naturally recovers.
This automatic control is designed to reduce excessive drawdown and help maintain more stable groundwater sampling conditions.
The basic operating principle is:
Water Level Monitoring
↓
Water Level Drops > 10 cm
↓
Automatic Pause
↓
Water Level Recovery
↓
Automatic Resumption
This reduces the need for technicians to repeatedly adjust the equipment manually.
316 Stainless Steel Pump Body
AML918 uses a 316 stainless steel pump body.
The material provides:
- Corrosion resistance
- Resistance to scaling
- Better tolerance for highly mineralized groundwater
- Improved durability in demanding groundwater environments
Material selection is particularly important for groundwater sampling equipment because groundwater chemistry can vary significantly between monitoring wells.
A more corrosion-resistant pump construction can help reduce equipment-related problems during long-term field use.
According to AIMOLI’s product information, the service life of the AML918 pump is designed to be approximately three times that of ordinary groundwater sampling equipment.
Actual service life depends on groundwater chemistry, operating frequency, maintenance and field conditions.
Why AML918 Is Different From a Basic Groundwater Sampler
The main difference is not simply the pump itself.
AML918 is designed as an integrated groundwater sampling system that considers the complete workflow:
Well Purging
↓
Water-Level Control
↓
Flow-Rate Adjustment
↓
Groundwater Sampling
↓
Sample Quality Control
This approach addresses several practical problems that can occur when groundwater sampling depends heavily on manual operation.
AML918 for Deep Groundwater Monitoring Wells
The original project involved a 120-meter-deep monitoring well.
Deep wells can create additional challenges for groundwater sampling because:
- More time may be required for purging
- Larger pumping volumes may be involved
- Manual operation becomes more difficult
- Water-level changes need to be monitored
- Sampling consistency becomes more difficult to maintain
AML918 is designed to provide a more controlled approach to these conditions.
For projects involving deep monitoring wells, the actual configuration should be selected according to:
- Well depth
- Well diameter
- Static water level
- Required pumping depth
- Groundwater conditions
- Required sampling flow rate
- Sample type
Groundwater Sampling and Sample Volatilization
Sample volatilization is an important concern when groundwater samples contain volatile compounds.
The sampling equipment and operating procedure can affect the amount of disturbance and exposure that occurs during sample collection.
AML918 is designed to provide controlled pumping and sampling, helping reduce unnecessary disturbance during groundwater sample collection.
However, sampling equipment alone cannot guarantee sample integrity.
For VOC and other volatile-compound analyses, the complete procedure should also consider:
- Purging method
- Pumping rate
- Sample container
- Sample transfer method
- Headspace
- Sample preservation
- Decontamination
- Transportation
- Laboratory requirements
Therefore, AML918 should be used as part of a complete groundwater sampling quality-control procedure.
From a Low-Cost Purchase to a Higher-Cost Project
The original project demonstrates an important lesson in groundwater sampling equipment selection.
The initial decision was influenced heavily by purchase price.
However, after the equipment was used in the field, the project team encountered:
More than 4 hours of well purging
↓
Severe sample volatilization
↓
Repeated test-data review failures
↓
Repeated sampling
↓
Project delays
The actual project cost therefore became much higher than the initial equipment purchase price suggested.
For professional environmental monitoring projects, the total cost of ownership should include:
- Equipment purchase price
- Labor
- Field operating time
- Repeated sampling
- Transportation
- Data-review failures
- Project delays
- Equipment maintenance
This is why sampling efficiency and quality control should be considered alongside equipment price.
AML918 Groundwater Sampling System: Key Advantages
1. One Pump, Two Functions
AML918 integrates well purging and groundwater sampling into one system.
High flow can be used for purging, while low flow can be used for sampling.
2. Automatic Water-Level Control
The dedicated water-level drawdown control unit automatically pauses operation when water-level drawdown exceeds 10 cm and resumes after recovery.
3. 316 Stainless Steel Construction
The pump body is made from 316 stainless steel, providing corrosion resistance, anti-scaling properties and better tolerance for highly mineralized groundwater.
4. Reduced Dependence on Manual Operation
Automatic control reduces the need for technicians to continuously adjust the system manually.
5. Designed for Professional Groundwater Sampling
AML918 is designed for groundwater monitoring wells and environmental sampling projects where sampling efficiency and quality control are important.
6. Suitable for Deep-Well Sampling
The system can be configured for deep monitoring wells, including the 120-meter-deep well involved in this case.
AML918 Technical Information
| Item | AML918 |
|---|---|
| Product Type | Groundwater Sampling System |
| Main Applications | Groundwater well purging and sampling |
| Sampling Method | High-flow purging + low-flow sampling |
| Water-Level Control | Automatic drawdown control |
| Automatic Pause Condition | Water level drops more than 10 cm |
| Pump Body Material | 316 Stainless Steel |
| Deep-Well Application | Suitable for deep monitoring wells; 120 m case application |
| Applicable Standards | HJ1019-2019 and HJ164-2020 according to manufacturer information |
| Service Life | Approximately 3× ordinary sampling equipment according to manufacturer information |
| Main Sampling Concern | Groundwater sampling efficiency and quality control |
Actual performance depends on well conditions, groundwater chemistry, sampling depth, operating parameters and maintenance.
When Should You Consider an AML918 Groundwater Sampling System?
AML918 may be suitable when a groundwater sampling project has one or more of the following requirements:
- Deep monitoring wells
- Large well-purging volumes
- Multiple monitoring wells
- Controlled sampling flow
- Reduced manual operation
- Groundwater sample quality control
- VOC-related groundwater sampling
- Long-term environmental monitoring
- High sampling efficiency
Before selecting equipment, users should provide the well depth, well diameter, water level, sampling depth and required sampling method so that the appropriate configuration can be determined.
Conclusion: Groundwater Sampling Equipment Should Be Evaluated by the Complete Project Cost
The experience of this municipal testing department shows why the cheapest groundwater sampler is not always the most economical choice.
In this case, a 120-meter-deep monitoring well required more than four hours of purging, groundwater samples experienced severe volatilization, and the resulting test data repeatedly failed review.
The problems ultimately forced the project team to reconsider its original equipment selection.
The AML918 Groundwater Sampling System addresses these challenges through:
- One-pump dual-function operation
- High-flow well purging
- Low-flow groundwater sampling
- Automatic water-level drawdown control
- 10 cm automatic pause threshold
- 316 stainless steel pump construction
- Deep-well sampling capability
- Reduced dependence on manual operation
For professional groundwater monitoring projects, the right sampling equipment should be evaluated not only by its purchase price, but also by sampling efficiency, sample quality, labor requirements, equipment reliability and the risk of repeated field work.
About AIMOLI Groundwater Sampling Equipment
AIMOLI Environmental Instruments develops and manufactures groundwater sampling and environmental monitoring equipment.
Its product range includes:
- Groundwater sampling systems
- Groundwater multiparameter analyzers
- Low-flow bladder pumps
- Groundwater flow velocity and direction instruments
- Downhole inspection equipment
- Environmental monitoring instruments
AIMOLI provides groundwater sampling solutions for environmental testing departments, environmental consulting companies, laboratories, groundwater investigation teams and other professional users.
Aimoli Environmental Instrument — precision that leaves competitors in a rush.
