Recommended Monitoring Frequency of Seepage Flumes and Weirs

For those unused to measuring seepage from embankment dams knowing when to measure can sometimes be challenging. In its Embankment Dam Instrumentation Manual, the Bureau of Reclamation lays out how frequently inspections should be made.

Note that the table below indicates only the minimum frequency of seepage readings. Depending upon a site's unique conditions, more frequent (even daily) monitoring may be necessary.

Thankfully, with the field instrumentation available today, continuous seepage monitoring can be readily achieved. If continuous monitoring is not possible, the recommended schedule is as outlined below:

Frequency Guidelines for Reading Seepage Flumes and Weirs ¹
During Construction		During First Filling	Periodic Report - Operations
Construction	Shutdown ²		First Year	Regular ³
Monthly	Monthly	3 Times a Week	Monthly	Monthly
¹ All entries indicate a MINIMUM frequency of readings. Readings may be required more frequently (even daily) for certain installations.
² Weather permitting.
³ When thee are no apparent problems at the facility.

It is important to remember that even with continuous measurement instrumentation, periodic visual inspection should also be performed. This inspect should not only include the seepage measurement devices, but also the seepage collection system, as well as the surrounding area.

Weirs in particular require regular, routine maintenance. While flumes tend to require less maintenance than weirs - as they have no crest which must be maintained and kept clear of debris to properly operate - they do require periodic inspection for shifting / settling and blockage.

Source: Embankment Dam Instrumentation Manual, U.S. Department of the Interior, Bureau of Reclamation, January, 1987