Cost Effective Monitoring
The cost of the instrumentation and materials usually makes up a tiny proportion of the cost involved in designing, planning and approving the installation, establishing access, drilling and installation work, slowing or moving production to accommodate the installation and then the ongoing efforts to continue monitoring. All time and money wasted in attempt to save money by skipping experienced monitoring staff.
Manual monitoring of a construction site is work that is often underestimated. The reason this work is so often overlooked as “simple”, is because the work is slow, repetitive, time consuming and laborious. Work you might otherwise give to a graduate or (seen all to often) a labourer. But when left to inexperienced or untrained personnel, the difference between good quality data and poor quality data quickly becomes clear. Poor data can render an instrument useless – and sometimes worse than useless.
With so many automated options available on the market, there are still some valid reasons to opt for manual monitoring. Reasons such as adaptability, cost, and the value of physical inspection. Below I’ve detailed these reasons, and described why they may be losing their weight.
Cost
When looking at the installed materials alone it may seem the cost of installing in-place geotechnical instrumentation is significant. The napkin analysis is easy:
(CL * N) + RO – A
Where CL is cost of labour per reading, N the number of readings over the duration of the project, RO is the cost of readout equipment and A is the cost of automation.
A good engineer might dig deeper and add on the cost of calibration of their equipment, perhaps replacement readout equipment during calibration or back up equipment for contingency. What is harder to quantify is the impact of unforeseen changes. Delayed project? N goes up! Extended consolidation period? N goes up! Unexpected movement demands increased monitoring frequency? N goes up – and potentially more readout equipment is needed to allow further monitoring teams to be mobilised. Damage to readout equipment (not uncommon when the aforementioned inexperienced workers are handed the task of caring for it)? Cost (both money and time) of repair or replacement.
Then there’s the risk, as discussed above, of operator error leading to erroneous data. That could either render the data useless or worse, lead to misinformed decisions. The cost of the former might be sending someone out to repeat the reading. The cost of the latter almost limitless.
Adaptability
In-ground instruments are more often than not placed at the center of the action. This means when the embankment is being raised or the excavation is starting, the instrument needs adapt to its surroundings. Adding or removing sections of casing is a far more attractive option than pulling dozens of expensive sensors out of the ground, adapting the installation, reinstalling, waiting for them to settle only to go back out and do it again in a few days time, right in the thick of the construction activity.
Osprey Measurement Systems have specifically designed their instruments to be easy add, easy remove, easy adapt so your instruments can work with you.
Physical Inspection
No one will question the importance of an engineer’s boots on the ground, at the coalface witnessing site conditions, monitoring visual cues that might indicate something not represented in the data. While qualitative, a visual inspection can provide more information than hours of data mining ever could. And to the end that a manual monitoring schedule prompts engineers or operators out onto the field, this is a plus.
But, you need to know what to look for. The inspection needs to be carried out by someone with the appropriate training and experience. The value of the monitoring visit is contingent on the quality of the person being sent to site and as discussed above, the task can often be allocated based on cost rather than capacity.
An automated monitoring system allows knowledgeable, experienced engineers to make a visual assessment the priority when conducting an inspection, and the time not spent conducting manual surveys can be spent reviewing the data, supplementing it with qualitative information and issuing tangible, actionable reports.
Summary
The lifetime cost of an instrument extends far beyond the materials installed. It extends backward to the planning and enabling works, installation, ongoing monitoring, maintenance, reporting, disruption to production and so on. Selecting the right equipment to automate your monitoring may seem like an additional expense, but when accounting for reduction of risk, increased quality and frequency of reporting, and the recovered opportunity cost of the engineer’s time, the balance quickly shifts in favour of in-place measurement equipment.