Consider Site Conditions
Consider the site conditions to ensure you get the most out of your settlement monitoring scheme.
Elevation Variation
The maximum difference in elevation between the highest point of the system and the lowest sensor is 5m.
Note: Because the system is fully sealed, the reference sensor can be at a higher elevation, or lower elevation than the measurement sensors, as long as they are all within that 5m vertical band.
While 5m is typically ample for structural or earthworks projects, it may not be for applications such as pipelines or dams where the ASP may be installed on a gradual slope.
Where an ASP is extended using a second ASP as described above, the elevation range resets, allowing you to extend the limits both laterally, and vertically.
Temperatures
The ASP performs best in moderate temperatures (between 0 and 25°C), but can accommodate extremes of -20 up to 50°C during operation. For installation outside of these temperature ranges, contact Osprey Support for guidance.
Burial is the best protection against temperature extremes. Consider the depth of your frost layer and ensure the ASP is installed below it for improved measurement performance.
Temperature variations across the system will impact measurement performance.
Where these can not be mitigated through burial or other means of thermal protection, measurements at night should provide stability as temperatures normalise.
Protection of the ASP
The ASP is designed and built to be robust, with the construction environment in mind. However there are some sources of force that must be considered when planning the installation:
Where the host material for the ASP contains large aggregate, rocks or other large debris, the ASP should be protected to avoid point loading or piercing.
This can be achieved by installing within a trench backfilled with a clean fill such as sand or other filtered material, as described in the Installation Guide section.
Risks Posed to Site by ASP Installations
Seepage
The installation of the ASP – particularly when installed within a sand filled trench – can create a seepage path which may present issues where piezometers are installed nearby or in water retaining structures.
Mitigation Options:
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Use a bentonite/sand mix to mitigate water migration
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Install compacted bentonite plugs by using solely bentonite powder or pellets over a 2m section of the trench.
Fire
MDPE, which makes up the majority of the ASP's body, is fire enabling and therefore not suited to applications with high fire risk without appropriate measures being taken.