Northwell Health Southside Hospital Expansion

GZA was contracted by another engineering firm to provide geotechnical services for the proposed building to be located at proposed Northwell Health Southside Hospital Expansion located at 301 E Main Street, Bay Shore, NY. 

The scope of expansion includes demolishing the 1-story outpatient rehab facility with a footprint of about 15,300 square feet (sf), construction of a new 6-story expansion building, a new parking garage and new canopies. The new 6-story expansion building will be located on the West side of the existing hospital building adjacent to the oncology center. The 3-level parking garage will be located on the northeast corner of the site, bounded by Union Boulevard to the north and North Montgomery Avenue to the east.

Challenge

A challenge that presented itself throughout the during of this project was the shallow groundwater depth, which was as shallow as two feet below the ground surface in some areas of the site. This presented challenges to the design and construction of this project. 
 

Solution

Subsurface Exploration: GZA reviewed a previous subsurface exploration and geotechnical report performed by others, including 9 borings and 19 cone penetration tests (CPT) drilled within or adjacent to the proposed construction areas. 

GZA performed a supplemental subsurface exploration program consisting of five borings and eight CPTs with seismic testing. The soil profile consists of approximately four to six feet of fill material, underlain by 50 to 60 feet of loose to dense sand, underlain by stiff to very hard clayey silt or sandy silt extending to a depth greater than 100 feet.  

The proposed column loads ranges from 1000 kips to 2600 kips. GZA recommended several foundation support options for the proposed structures, including shallow foundation, Concrete-Filled Steel Pipe Piles, and Drilled Micropiles.

Groundwater Monitoring: GZA was retained to perform continuous groundwater monitoring in six groundwater observation well locations. GZA installed six Solonist Leveloggers and one Barologger. Leveloggers are piezometers, installed below the groundwater level, that measure and record the absolute pressure of a fluid through a fully automated system. A Barologger is installed above the groundwater level and measures the ambient atmospheric pressure. These instruments were programmed to record the fluid pressure every two hours allowing fluctuations in groundwater levels to be recorded. The height of the water column above the Levelogger was obtained by calculating the difference between the two pressure readings from the Barologger and Leveloggers. 

Manhole Video Inspection and Pipe Jetting: GZA managed our subcontractor to perform video inspections and pipe jetting of five manholes and their connecting utilities.  GZA observed and documented the findings of the field work in a summary report. 

Construction Administration, Observations, and Special Inspections: GZA was retained during the construction phase of the project for construction administration services including attending construction meetings, review of contractor Requests for Information (RFIs), review of geotechnical and foundation related submittals, and review of shop drawings. 

Additionally, GZA was retained to provide construction observations, special inspections of the pile installation, load testing, and foundation construction, and site visits to assist the design team in resolving any foundation or geotechnical related issues that arose over the course of the project.

GZA was onsite to observe Static Pile Load testing of the test pile and the installation of the production piles. The pile program consisted of 27 - 12.75-inch, pressure grouted, micropiles advanced to a depth of approximately 48-feet below the ground surface. 
 

Benefit

GZA provide practical solutions to help the hospital expansion project get built and overcome challenges.