There shall be a minimum one foot vertical separation between the highest groundwater table beneath the proposed location of any structure or building and any footing or foundation for such structure or building. Where a structural engineer certifies to the Building Department that additional support structures are required for structural support, the construction may include piles used below the one foot vertical separation. Helical piles shall be used, except in instances where a structural engineer certifies that site and groundwater considerations prevent the use of helical piles. Where non-helical piles are used, such piles shall be driven to an elevation where there is adequate resistance to support the proposed structure, as certified by the structural engineer. Where the installation of pilings includes any vibratory mechanism, the installation shall be subject to the following requirements:
A.
There shall be established a zone of impact, the outer boundary of which is the line formed upon the surface at a 45° angle from the bottom tip depth of the driven sheet pile.
B.
Pile driving shall be performed in a manner that limits vibrations at any structures on adjoining and nearby properties, as well as roadways and public infrastructure, within the zone of impact to a maximum of 0.25 inches per second.
C.
All pile driving work shall be monitored by a monitoring company, which shall provide on-site personnel.
D.
The monitoring company shall provide the Building Department with vibratory monitoring specifications and protocol that includes construction installation progress, recommended property protection measures, a delineation of the location of all proposed monitoring measuring devices, confirmation of the means and methods of installation, contact information for personnel providing monitoring service on-site, and daily logs showing vibratory measurements.
E.
Prior to the commencement of any sheet piling, a conditions survey shall be provided for all structures within the anticipated zone of impact.
F.
Upon the exceedance of vibratory limits and/or based on actual field conditions negatively affecting installation including changing procedures to produce vibratory impacts below threshold amounts, subject to approval by the Building Department, the building permittee shall modify the means and methods of installation.
G.
Any other requirements of the Building Department.