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I Geotechnical Engineering Report Addendum 1 Micropile Foundations— Evergreen Way Pump Station In Everett, Washington lierracon August 2, 2021 ■ Terracon Project No. 81195189 should occur following completion of all micropile installation and testing activities have been completed. The contractor should observe the existing pump station building for signs of distress during installation and testing of micropiles. If distress is observed, the contractor should take action to stabilize the existing building, then evaluate the situation to determine corrective action. One field verification tension test should be performed on a test micropile prior to installation of production piles. The location of the verification test pile should be selected by the contractor and approved by the I City of Everett.Verification maximum test load should be 2 times the design load (allowable stress design) or the nominal capacity of the pile (LRFD design). The verification test micropile may be incorporated into the work as a production pile following completion of testing with satisfactory results. If soil conditions or I means and methods of installation vary, additional verification tests will be required. The verification test schedule should be incorporated into the Plans and Specifications for the project. I The micropile load testing procedures should be in general conformance with the procedures outlined in Chapter 7 Publication No. FHWA NHI-05-039 published by the U.S. Department of Transportation Federal Highway Administration. The ground anchor testing and stressing provisions and acceptance criteria found in 6-17.3(8) and 6-17.8(9), respectively, of the Washington State Department of Transportation (WSDOT) Standard Specifications for Road, Bridge, and Municipal Construction are generally applicable to testing of ground anchors. The following list notes key exceptions: e It is not necessary to test each micropile. We recommend the minimum number of tests above. ✓ Verification tests as described in the WSDOT Standard Specifications and Special Provisions should not be required. Performance Testing per the WSDOT Standard Specifications is consistent with verification testing as described in FHWA NHI-05-039 and this report. a The WSDOT Standard Specifications are prepared for LRFD design. The fractions of the full design load in the tables should be doubled for ASD. • Micropiles do not usually have an unbonded length as part of their design. Minimum elongation I requirements of the unbonded length should only apply if the micropile is designed with an unbonded zone. E Micropiles are not post tensioned elements. Discussion of lock off load should be ignored. Typically, 5-percent of production micropiles are proof tested. Based on the limited number of micropiles we recommend that one proof load test be required along each wall where micropiles are installed. If a verification test with acceptable test results is incorporated into the production piles, a proof test need not be performed along the wall with the verification test micropile. I Micropile load testing should be completed using a load frame capable of distributing large test loads into the near-surface soils without damaging existing structural elements or below-ground utilities. The large test loads frequently cause damage to slabs-on-grade and other nearby improvements, and the location of pile load tests should be reviewed during the design phase to minimize impacts to existing improvements. I I Responsive■ Resourceful at Reliable 3 I