• If the stop work threshold is exceeded, evaluate the condition of the building for damage. If no damage is indicated consult with structural engineer and/or architectural historian to assess whether higher thresholds are possible and adjust as appropriate.
• If damage occurs determine if any other construction approaches are feasible to reduce vibration. If none is available examine the severity of the damage to determine if damage is minor and repair is feasible. If repair is feasible continue with construction, but monitor vibration and damage closely to ensure that damage remains repairable. Consider whether a lower stop work threshold is feasible.
• If damage approaches becoming unrepairable and vibration levels have approached or exceeded the stop work threshold repeatedly, reconsider construction of the project.
• Repair any damage that has occurred.

Page 4.J-26     OSEC-404 [See page 5-360 for the original comment], SFPUC-4 [See page 5- 77 for the original comment] ADD the following Mitigation Measure 4.J-2c after Mitigation Measure 4.J-2b:

Mitigation Measure 4.J-2c: All development sites requiring pile driving shall have underground utility5 surveys completed before a building permit is issued to demonstrate that pile driving will be located a minimum 15 feet from buried utilities. Underground utilities surveys shall be submitted to the City for review and consultation with affected utilities a minimum of two weeks prior to commencement of construction activities. If underground utilities are identified within 15 feet of proposed pile driving activities, alternative pile installation methods shall be required.

Alternative methods may include use of sonic drivers or drilled and cast-in- place piles. All pile driving shall be designed so as to result in peak particle velocity of less than 4.0 in/sec (100 mm/s) at the location of underground utilities.

Within one week following completion of pile driving activities, a post- construction assessment of all underground utilities within 30 feet of the pile driving activity shall be submitted to the City by the contractor, confirming that no damage to any underground utilities occurred as the result of the pile driving activity. Should the post-construction assessment determine that underground utilities were damaged by pile driving activities, such damage shall be repaired by the contractor to the satisfaction of the City and affected utility.