Forensic

FORENSIC GEOTECHNICAL ENGINEERING

JZN Engineering provided forensic geotechnical engineering services to investigate the failures of geotechnical origin produced in a structure. The investigation involved data collection, characterization of structural distress, diagnostic test, analysis of data, development of failure hypothesis, reliability checks and recommendations.

Subsurface investigations were conducted in order to obtain information on subsurface soils and groundwater conditions. The data was used to estimate the engineering characteristics of the soil, determine the suitability of the existing bearing materials, perform settlement analysis and slope stability calculations that can be used to find the possible causes of the structure’s failure and to provide recommendations for the structure’s remediation.

JZN provided construction quality control during the structure’s remediation process in order to assure the recommendations provided after the forensic investigation are followed according to specifications. This included soil bearing capacity testing, inspection of additional foundation support installation, and materials testing for concrete, asphalt and structural steel.

PROJECT SERVICES

¨ Subsurface Investigation

¨ Laboratory Testing of Soils

¨ Settlement Analysis

¨ Slope Stability Analysis

¨ Contractor Support

¨ Construction Quality Control/Special Inspection

OWENS MANOR BUILDING DISTRESS
DOVER, DELAWARE

JZN Engineering conducted a forensic geotechnical engineering investigation to find the possible failures of geotechnical origin produced in an existing four (4)-story residential building with no basement located in Dover, Delaware. The investigation aimed to find the causes of ongoing settlement at the existing building in order to provide geotechnical engineering recommendations for a prompt and cost effective remediation of the existing structure.

JZN Engineering conducted a subsurface investigation that included drilling soil exploration borings outside the existing building and as close as possible to the building’s exterior walls. The forensic geotechnical investigation revealed the existence of loose uncontrolled fill material followed by a thick stratum of compressible soft organic river deposits. JZN concluded that the ongoing building settlement was possibly caused by the fill and organic materials consolidation generated by the applied building load.

JZN Engineering recommended the reinforcement of the existing building mat slab foundation which consisted on the installation of a deep foundation system. JZN recommended the utilization of helical piles that would extend beyond the fill and soft organic materials and bear on a dense stratum.

PROJECT SERVICES

¨ Subsurface Investigation

¨ Settlement Analysis

¨ Deep Foundation Design

GOYARD BUILDING DISTRESS
BOROUGH OF MANHATTAN, NEW YORK

JZN Engineering conducted a forensic geotechnical engineering investigation to find the possible failures of geotechnical origin produced in the existing five (5)-story with basement Goyard Building constructed in the 1930s. The investigation aimed to find the causes of excessive settlement occurring in the basement and underneath the existing eastern wall of the building.

JZN Engineering conducted a subsurface investigation to obtain information on subsurface soils and groundwater conditions, and to provide conclusions for possible causes associated with the ongoing settlement experienced by the structure. The investigation included drilling a soil exploration boring inside the existing basement and multiple site visits to observe any signs of existing and ongoing building distress such as slab and wall cracks, leaning stairs and building separation. The investigation and analysis of data collected revealed that ongoing building settlement was caused due to dewatering during a recent building underpinning process which increased the effective stress on the building.

JZN Engineering recommended immediate building stabilization consisting of underpinning the building foundation elements utilizing helical piles and foundation repair brackets.

PROJECT SERVICES

¨ Subsurface Investigation

¨ Settlement Analysis

¨ Deep Foundation Design

THREE-STORY RESIDENTIAL BUILDING DISTRESS BOROUGH OF BROOKLYN, NEW YORK

JZN Engineering conducted a forensic geotechnical engineering investigation to find the possible failures of geotechnical origin produced in the three-story residential building located at 139 Dwight Street in the Borough of Brooklyn, New York. The investigation was performed to find the causes of the ongoing settlement at the existing building in order to provide geotechnical engineering recommendations in support of the building stability assessment.

JZN conducted a forensic geotechnical investigation that included the review of all available plans and documents, a building crack visual observation, and a subsurface soil investigation by means of excavating one exploration test pit. The investigation showed the building was constructed between the late 1800’s and early 1900’s and was supported on a stone and wood foundation system. The building was renovated between 2006 and 2007; however, the renovations did not induce the building settlement. The investigation determined that the settlement was caused due to the construction of a new building during 2007 in the adjacent property. Specifically, the neighboring building was constructed on shallow foundations bearing on loose deep existing fill materials with the bottom of foundations installed approximately two feet higher than the older building.

JZN Engineering recommended immediate building stabilization by underpinning the existing building slab and foundations.

PROJECT SERVICES

¨ Subsurface Investigation

¨ Settlement Analysis

FEDEX FREIGHT FACILITY DISTRESS
CITY OF NEWARK, NEW JERSEY

JZN Engineering conducted a forensic geotechnical engineering investigation to find the possible failures of geotechnical origin produced in the FedEx Freight Facility located at 580 Delancy Street in the City of Newark, New Jersey.

JZN conducted a forensic geotechnical study consisting of drilling soil exploration borings outside the facility to identify the subsurface conditions. The investigation revealed uncontrolled, loosely placed fill materials overlaying soft compressible deposits. The study included a one dimensional consolidation testing of a representative sample within the cohesive strata in order to estimate the potential for consolidation of the underlying compressible soils. JZN determined that the settlement and building distress was caused due to the uncontrolled fill and soft compressible deposits below the building shallow foundations.

JZN Engineering recommended a number of options in support of the building stability assessment that included a periodic rate of settlement monitoring program with floor slab re-leveling from time to time; the demolition of the slab followed by the excavation of unsuitable fill materials and replacement with lightweight fill prior to the reconstruction of a new slab in order to slow down the rate of consolidation and prolong the life of the slab; and the building foundation underpinning using deep foundation systems in order to stabilize the building.

PROJECT SERVICES

¨ Subsurface Investigation

¨ Settlement Analysis and Monitoring

BANK OF AMERICA BRANCH OFFICE TOWN OF WARREN, NEW JERSEY

JZN Engineering conducted a forensic geotechnical engineering investigation to find the possible failures of geotechnical origin generated in the Bank of America Branch Office located at 59 Mountain Boulevard in the Town of Warren, New Jersey.

JZN conducted a forensic geotechnical investigation consisting of drilling soil exploration borings outside the existing building to obtain information of subsurface soil and groundwater conditions. The investigation was performed to find possible causes of the basement flooding and provide recommendations for the basement flooding mitigation and water-proofing. The soil borings revealed the groundwater level was located approximately at the same elevation as the basement slab. A visual observation of the existing building revealed rainwater entering through wall conduits, leaking and/or broken sump pumps, and sump pumps installed at wrong elevations.

JZN recommended replacement of broken conduits, installation of a floor drain system outside the basement door, installation of door waterstops, replacement of broken sump pumps and pipes, and installation of a french-drain system under the slab area to work in conjunction with the sump pump system.

PROJECT SERVICES

¨ Subsurface Investigation

¨ Water-Proofing Recommendations

WAREHOUSE/FREEZER SLAB REMEDIATION HUNTS POINT MARKET BOROUGH OF BRONX, NEW YORK

The project is located at 355 Food Center Drive in Hunts Point, Borough of Bronx, New York. The property is bordered by Food Center Drive to the west, and commercial buildings to the south and east.

JZN Engineering performed a forensic geotechnical engineering investigation and remediation to obtain information on subsurface soil, ice formation, and groundwater conditions of the site. The investigation was performed to find possible reasons that caused portions of the slab to lift. The forensic geotechnical investigation consisted of drilling of two soil exploration borings inside the existing building. The soil borings revealed the groundwater level was located approximately below bottom of slab. The combination of shallow groundwater table, and high fine content within the existing man-made fill, caused the fill to be nearly saturated due to capillary rise phenomena. Since capillary water is held within the soil due to tensions forces, it became susceptible to freezing when exposed to subzero temperatures creating upward movement to the columns and slab lifted and cracked.

JZN provided several recommendations to stop the ice formation below the building slab and pile caps, including overexcavation of the existing fill and replacement with coarse granular fill, or/and the installation of an underground heating system.

PROJECT SERVICES

¨ Subsurface Investigation

¨ Water-defrost Recommendations

¨ Foundation Remediation Recommendations

SCHOOLHOUSE BUILDING DISTRESS CITY OF HOBOKEN, NEW JERSEY

The project is located at 80 Park Avenue in the City of Hoboken, New Jersey. The site is presently developed with a four-story building with no basement and associated parking lot. The property is bordered by Newark Street to the north, Park Avenue to the east, and residential buildings to the north, east and west.

JZN Engineering conducted a forensic geotechnical engineering investigation to obtain information of the subsurface soil, and groundwater conditions. The investigation was performed to find possible causes of building’s ground floor slab-on-grade settlement, and provide recommendations for remediation action on the site. The geotechnical investigation consisted of drilling of two soil exploration borings outside the existing building. The soil borings revealed the subsurface soil consisted of organic clay deposits, which are highly compressible, and consolidated overtime under applied loads, making the slab to settle.

JZN provided recommendations to stop the slab settlement. As such, entirely removing the first floor slab and installation of a new structural slab supported on helical piles.

PROJECT SERVICES

¨ Subsurface Investigation

¨ Foundation Remediation Recommendations.

BUILDING REHABILITATION
CITY OF JERSEY CITY, NEW JERSEY

The project is located at 412 Second Street in Jersey City, New Jersey. The site is presently developed with a three-story building with a full basement constructed in the early 1900’s. The property is bordered by Second Street to the south, Park Avenue to the east, and residential buildings to the south.

JZN Engineering conducted a forensic geotechnical engineering investigation to obtain information of the subsurface soil, analyze the cause of building settlement and provide rehabilitation recommendations. The geotechnical investigation consisted of drilling of two soil borings outside the existing building, and four test pits inside of the building within the basement floor slab adjacent to the exterior building wall foundation. The soil borings revealed the subsurface soil consisted of deposits of organic clay, which is highly compressible, and can settle under applied loads. Tests pits investigation indicated the presence of the old basement brick foundation on the neighbor’s property. The placement of additional fill materials within the adjacent building basement in the 1940’s had caused consolidation of the organic clay deposits causing the settlement between the two sides of the building.

JZN provided recommendations to stop the building settlement, which included an underpinning system utilizing helical piles installed using portable equipment.

PROJECT SERVICES

¨ Subsurface Investigation

¨ Foundation Design Recommendations.

VAULT DOOR SETTLEMENT
POHATCONG, NEW JERSEY

The project is located at 707 New Brunswick Road in Pohatcong, New Jersey. The site is presently developed with a Bank of America Branch Office Building and associated drive-thru canopy, paved parking lot and driveways, landscape areas and associated utilities. The property is bordered by New Brunswick Avenue to the southwest, and residential two-story houses to the northwest, northeast and southeast.

JZN Engineering performed a forensic geotechnical engineering investigation to obtain information of the subsurface soil, rock and groundwater conditions, and provide recommendations for remediation of the bank vault door settlement. The geotechnical investigation consisted of drilling of three soil borings and obtaining rock cores. The soil borings revealed subsurface soil consisting of fill materials, and the vault foundations was placed to bear on top of the residual soils which explained the settlement of the vault door and minor to no apparent settlement of the vault slab.

JZN Engineering recommended a number of options including a short term and permanent fix. The short term solution included the vault door removal, and floor slab in front of the vault reconstructed 0.5 inch lower. The permanent fix included the vault door wall be underpinned using deep foundation system consisting of helical piles.

PROJECT SERVICES

¨ Subsurface Investigation

¨ Foundation Remediation Recommendations

DISTRESSED RETAINING WALL
HACKETTSTOWN, NEW JERSEY

The project is located at 114 Valentine Street in Hackettstown, New Jersey. The site is presently developed with a two story Verizon Facility with a full basement. The distressed concrete retaining wall is located at the western property line. The property is bordered by a three story house to the south, a parking lot to the west, a three story house to the north, and Valentine Street to the east.

JZN Engineering performed a preliminary forensic geotechnical engineering investigation to obtain information on the existing foundation elements, and provide recommendations for remediation of the concrete retaining wall. The investigation was performed to find potential causes of the retaining wall tilting. The geotechnical investigation consisted of a review of all available plans and documents along with a visual observation of the wall and the surface pavement conditions at the top of the wall. Based on the preliminary investigation, JZN hypothesized that the retaining wall movement may be attributed to local shear failure at the stem foundation connection or a global rotation due to soil failure.

JZN Engineering recommended additional investigation including soil exploration borings to evaluate subsurface soil conditions, a test pit investigation to evaluate the retaining wall footing/stem connections, a concrete compressive strength test on a concrete core sample obtained from the wall, and a global and local stability analysis.

PROJECT SERVICES

¨ Document Review

¨ Visual Investigation

¨ Additional Investigation Recommendations

FOREST AVENUE SHOPPERS TOWN BOROUGH OF STATEN ISLAND, NEW YORK

JZN Engineering conducted a forensic geotechnical engineering investigation to find the possible failures of geotechnical origin generated in the Forest Avenue Shoppers Town located at 1481 Forest Avenue in the Borough of Staten Island, City & State of New York.

JZN conducted an initial forensic geotechnical investigation consisting of the evaluation of readily available subsurface soil conditions and groundwater levels at and near the site, along with a visual observation of the site. The investigation was performed to find possible causes of the water infiltration and moisture causing damage to the existing basement floor slab and to provide recommendations for basement water infiltration mitigation and water-proofing. The groundwater monitoring wells at the site showed the groundwater level was located approximately at or potentially above the basement slab. Visual observation of the site found several basement sump pits that were non-operational, the presence of cracks in the basement foundation wall, insufficient grading at the ground surface and at the basement slab, water flowing from the fire hose connection, and some roof disrepair.

JZN recommended several site maintenance procedures in order to mitigate basement water infiltration prior to further forensic investigation, as several building elements in disrepair may be the cause of the infiltration.

PROJECT SERVICES

¨ Document Review & Visual Investigation

¨ Site Maintenance Recommendations