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CIEST tested two composite meter lids by two different manufacturers to a proof load of 40 kips to determine if this new material was an effective replacement for traditional cast iron lids. These tests were conducted according to standard AASHTO M 306-10. One composite meter lid was manufactured by EJ Durostreet and the other was manufactured by Trumbull. One cast iron lid was used as a reference, from Copeland Precast.��

Cast iron meter lids are currently the industry standard, and the default material used for the vast majority of water meters. The main downside of traditional cast iron water meter lid is that it is very heavy, demanding more resources for handling thus it often poses a work-related safety hazard. Fiber reinforced composite meter lids offer a lighter alternative. The behavior of these composite meter lids is, however, much less studied than that of the traditional cast iron lids.

The standard specifies that a proof load of 40 kips (178 kN) must be applied to the lid via a 9”x9” area. Upon reaching this load, the position of the actuator should be held for one minute and then released. After the 40-kip proof load was applied, the lids were visually inspected for any permanent deformation, cracking, or other defects. Per Denver Water’s request, upon the meter lids had successfully passed the requirement set by the standard, the lids were then further tested to failure or up to 70 kips, whichever came first.��

The loading rates were calculated based on an initial stiffness test of each material, aiming for 500 lb/s as the standard specified the loading rate must be between 100 and 1000 lb/s. The Durostreet lid reached the target load of up to 70kips (exactly 72.1 kips), however the Trumbull lid could not be tested beyond 60 kips due to deformation and cracks developed, which tilted the horizontal load balance. The cast iron lid was tested up to 70 kips and rendered direct comparison against two composite lids.��

The Durostreet and Trumbull lids proved to be more elastic than the traditional cast iron lid. The Durostreet lid was tested to 72.1 kips and did not exhibit permanent deformation as the LVDT returned to its initial position exactly. All three lids passed the proof load test as they were not visually observed to have any cracking, permanent deformation or other defects after applying the 40-kip load, and as specified in the standard, the recorded permanent deformations were not greater than 1/8” (0.125”) after applying the 40 kip load. The Trumbull lid showed deformation and cracks around 60 kips, yet it did pass 40kips without visible defects under the testing standard.��