considered a variety of factors in assessing the efficacy of Schnabel's sheeting and shoring system, not just its use of soldier beams and wood lagging. He considered the soil conditions on Pennsylvania Avenue, the amount of toe in of the soldier piles, the size of the piles, the spacing of the soldier beams, and the number of levels of tiebacks. He also considered the nature of the Sears Building -- the structure within the zone of influence behind the excavation which the system was intended to protect.
Brown's expert opinion was that the sheeting and shoring system designed and installed by OMNI was not adequate protection for the adjacent Sears Building. He researched a number of construction projects under similar conditions in the Pennsylvania Avenue area. Most importantly, he examined the sheeting and shoring systems for four excavations within the immediate vicinity and compared them to Schnabel's.
These four sites were 625 Indiana Avenue; the Canadian Embassy at 4th and Pennsylvania Avenue; the District of Columbia Courthouse at 6th and Indiana Avenue; and 1001 Pennsylvania Avenue at 10th and Pennsylvania Avenue.
Brown stated that Schnabel failed to meet the standard of care for a sheeting and shoring system along Pennsylvania Avenue because it did not incorporate in its design additional precautions to protect against settlement damage. From his research and experience, he concluded that such precautions are generally used when soldier beams and wood lagging are used in similar soil conditions adjacent to a property not underpinned and subject to settlement. These additional precautions -- solid steel sheeting or slurry walls
-- were not used by Schnabel at this project site. This failure was a significant factor which compromised the strength of the sheeting and shoring support system. In addition, the standard of care for the embedment of the soldier piles was at least five foot toe-in below the footing level and into good material. At comparable sites, this toe-in was between seven and twelve feet and all these projects utilized at least two levels of tiebacks.
By contrast, the average toe-in of the soldier piles at the Project was three and one-half feet and only one level of tiebacks was used.
Brown's opinion is supported by pile deflection data collected by OMNI after the August settlement which showed that the soldier beams had significant movement. OMNI's survey crews took readings on the soldier piles on August 23, 1984. They recorded a three to five inch movement of the soldier beams at the Sears property line. OMNI's field engineer determined that in late August the northeast corner of the building had settled one-half inch and the southeast corner had settled one-eighth inch. At this time the tiebacks had not yet been installed, but lagging boards had been placed for a nine foot height. The excavation was twenty-two feet deep. This supports Brown's conclusion that between August 20th and the 23rd or 24th, the soldier beams moved while they were acting in cantilever and because they did not have an adequate toe in to the sand and gravel.
With respect to the second settlement in November, the final excavation had begun and at this point the sheeting and shoring system was bearing the most pressure. The tiebacks were stressed to the maximum design load and were supporting the full thirty five feet of soil. At this deeper elevation, Brown explained, the clay is softest and the largest amount of soil pushes the clay down and through the soldier beams. The evidence supports his conclusion that at this time the system was simply not strong enough to hold back this amount of soil pressure without giving. The tiebacks yielded, which allowed the soldier piles to move further and the soft clay to move past the piles before the lagging boards were put in place. As a result the earth underneath the buildings expanded laterally and the foundation of the Brady Building settled vertically.
Independent evidence that the soldier piles deflected during the beginning of November supports Brown's conclusion. The movement of the soldier piles was measured by two different sources, by Fred Lifson for OMNI and by Steven Pennington for Schnabel. Steven Pennington began taking readings around August 25 after the first settlement. He took periodic measurements -- roughly once a week -- and provided this information to Mr. Wlaschin at the site. In contrast, OMNI's field engineer Fred Lifson took readings for OMNI every day, sometimes twice a day.
The pile deflection data taken by each, however, revealed different results. Both compilations showed an outward deflection of the wall during the third week of August when the initial settlement took place. The two compilations of data are close to identical through the end of August and through September and October. Between October 26th and November 9th a major difference in readings occurs again, especially with respect to soldier piles 66, 67, 71 and 73.
However, most of the movement which recorded by OMNI during this time period was from soldier piles 71, 72, and 73 -- the location near the northeast corner of the Brady Building where the largest amount of settlement occurred. For example for soldier pile 72, OMNI's data recorded a movement of 7.2 inches and for soldier pile 73, OMNI's data showed movement of 4.6 inches.
Because of the frequency and the care with which the measurements were taken by Lifson, the Court is convinced that OMNI's data is the most reliable indicator of soldier pile movement and as such demonstrates that the piles did indeed move during the November settlement. Furthermore, it is unlikely that OMNI's data are "stray" readings, as characterized by Dr. Cording. Fred Lifson took these readings by placing a baseline across the soldier piles and measuring the distance. Brown explained that if the baseline was disturbed or shifted, all the measurements would be likely to shift the same amount rather than record different readings. Furthermore it is undisputed -- even by Schnabel and Dr. Cording -- that displacements of the wall of three to five inches did occur during the August settlement.
And it is also agreed that displacements of two to seven inches -- if OMNI's data is taken as reliable -- would have evidenced a failure of the wall during the first weekend in November.
The Court is convinced by OMNI's data as well because the results of OMNI's tests comport with the predictions of almost all the engineering consultants who examined the system both before and after the August and November settlements. After the August settlement, Mueser-Rutledge also believed that the initial settlement was caused by the movement of the soldier piles. In a letter dated September 21, 1984 Mueser-Rutledge concluded that with respect to the completion of the excavation to the full thirty-five feet, a five foot embedment of soldier piles as shown in Schnabel's drawings would not be enough to provide a reasonable safety factor against failure.
And this was the conclusion reached by most of those on the scene after the two major settlements. After the November settlement, the Project's lead structural engineer Ellis Whitby visited the construction site. He testified that he could see that the soldier piles were tilted from the bottom outward to the top and that they were leaning into the excavation. In fact, Daly had to redesign the foundation wall because several piles in that location protruded into the reinforcing pattern. Even when the building was complete the soldier piles were still out of line -- the piles adjacent to the Sears Building were four inches and eight inches into the foundation wall. This interference with the maximum thickness of the foundation wall also suggested to Mr. Forma, Westminster's development manager for the Project, that the piles had moved significantly during the weekend of November 3-4.
It was Mr. Whitby's on-site opinion
that the sheeting and shoring system had moved inward. Immediately after the second settlement, he observed more evidence that the soldier beams had moved, namely the appearance of horizontal cracks along the cutback and at the bottom of the excavation. Whitby also observed that the soil adjacent to the toe of the piles had "heaved" up vertically. "Heaving" occurs when soil at the bottom of the excavation rises up due to the pressures developing against the wall and the soil penetrating around the wall. This kind of heaving is once again indicative of the movement of the soldier piles.
The Court finds that the cause of the movement of the soldier piles was the faulty design and installation of the sheeting and shoring system. First, the preponderance of the evidence demonstrated that during installation the soldier piles were driven to an insufficient depth and that they were driven into clay and not gravel. SEA had recommended that given the Brady Building setback the soldier beams should be driven seven to ten feet into the sand and gravel rather than five feet below the mat foundation as shown in Schnabel's drawings. After review of the Schnabel drawings, SEA recommended the soldier beams should be driven five feet into sand and gravel. However, Schnabel did not drive the piles to the tip elevation. After the first settlement, approximately August 24th, Schnabel checked the elevations of the soldier piles and discovered that they had not achieved a five foot depth. When Schnabel discovered the elevations of the piles had not met the required depth, it designed and installed toe rackers for these piles to ensure proper support. As of the settlement in November, however, only two of these braces had been installed -- at soldier piles 72 and 74.
The inclinometer data does not compel a different conclusion. An inclinometer is a vertical tube drilled into the ground which allows a measuring device to be installed within it. At different intervals this measuring device is run down the tube to record any motions. At the Project site, STS and Skidmore took measurements from the inclinometers for Sears. The device was installed after the first settlement in August to record any movements in the soil.
Schnabel maintained that the measurements from the inclinometer between the excavation and the Brady Building showed no significant lateral soil movements during the first week of November. However, the inclinometers were not installed in the area where most of the movement of the soldier piles took place -- in the northeast corner adjacent to the Sears' Building. Instead the inclinometer was located approximately six to eight feet from the Sears Building and twenty feet from the wall of the excavation. Thus the inclinometer could not have been expected to measure this lateral movement. It was positioned where the Sears Building itself was moving downward as the settlement took place. This data is not helpful in determining what was occurring at the northeast corner of the Brady Building. Furthermore, there were no readings done over the weekend of November 3rd and 4th -- when the abrupt settlement took place -- because the inclinometer required repairs.
The evidence also showed that the tiebacks failed and did not support the system when the final excavation was made and that this was a major cause of the November settlement.
Tiebacks consist of steel cables which have been drilled into the ground and grouted with concrete. They provide lateral stabilization for the sheeting and shoring system and keep the soldier piles from moving. They ensure that the sheeting and shoring system remains vertical and prevent it from tipping into the excavation due to the pressure from the earth on the opposite side.
Originally, SEA had recommended that the tieback anchors penetrate the sand and gravel layers and be installed at a maximum angle of 30 degrees. It warned that tiebacks should be installed in sand and gravel because when placed in clay they tend to slip and lose some of their holding power and may yield considerably at full design load. This type of installation also minimizes the length of the tiebacks. Because the greater strength in sand and gravel the tiebacks do not have to extend as far under the adjacent property's foundation.
The Court finds that the tiebacks were installed in clay and that this did not meet the standard of care for tieback installation given the other factors involved with this Project. Plaintiff's expert Brown testified that when a tieback starts pulling out of its hole, it causes a disturbance by softening and removing the clay around the anchor. This also affected the settlement of the Sears Building. Moreover since only one level of tiebacks was used for this system, the tiebacks were at a higher level in the soft clay under the Brady Building and were closer to its foundation. The tiebacks yielding would account for the movement of the soldier piles which occurred during the first weekend in November.
Although it was unclear from the shop drawings whether the tiebacks were intended to be anchored into clay,
the evidence indicates that the tiebacks were not installed in the sand and gravel stratum as Schnabel's shop drawings specified. This was the conclusion of almost everyone on the Project site, including Mr. Winter of SEA and Mr. Whitby of Daly. Even more persuasive is the evidence that a number of tiebacks near the settlement points were determined to have failed their proof tests. Brown testified that tiebacks would not have yielded so considerably unless they were installed in the soft clay stratum.
A tieback test is necessary to confirm that a tieback has sufficient anchorage to resist the load for which it was designed. At the Project site, Schnabel performed the tieback tests, and the results were observed and recorded by the Law Engineering Testing Company, an engineering company which provides inspection and testing services, retained by Westminster. During the tests tiebacks are pulled back with more load than the design requires -- up to 120% -- to make sure that the tieback is functioning properly. The load on the tieback is increased incrementally, and at each increment movement of the tieback is recorded. Measurements are taken to the thousandth of an inch, and are measured at certain intervals (i.e., one through ten minutes).
If a tieback exceeds the movement set forth in the test, it is considered to have failed and to be susceptible to creeping. To compensate for a failed tieback, the tieback should be replaced or additional tiebacks should be installed.
The proof test set forth in Schnabel's design drawings provided that the allowable rate of movement in the last five minute interval of the test must be less than .01 inches (e.g., between five and ten minutes). The drawings also specified that any tieback which cannot be successfully tested to the loads required be incorporated into the sheeting using only one-half the load which it must hold without continuous movement.
Applying this proof test to tiebacks 62 through 81 (the twenty tiebacks adjacent to and around the corner from the Sears Building), Brown concluded that twelve out of twenty tiebacks failed.
Schnabel did not, however, replace them and took no further action to compensate for the failure of the majority of these tiebacks.
Given these results, the only logical conclusion is that the tiebacks were anchored in the clay and that they yielded, causing the movement of the soldier piles. And as the tiebacks gave way, there was a resulting disturbance of the material underlying the Sears Building. This did not comport with a industry practice or meet the standard of care for tieback installation.
There was also evidence that Schnabel failed to meet the standard of care because only one layer of tiebacks was installed. Brown established that whether two levels of tiebacks are required depends on the total height of the excavation -- from the top of the soil behind the soldier pile system down to the full excavation level. Brown testified that in the Washington D.C. area with similar soil conditions two levels of tiebacks are required for a total height of excavation of thirty-five feet, citing the four comparable sites.
If two levels of tiebacks are used, one tieback is not stressed to full design load but shares the strain with the second level. He concluded that a soldier beam and wood lagging system with six foot spacing of the beams but with only one level of tiebacks did not meet the standard of care for the design of a sheeting and shoring system along Pennsylvania Avenue.
Schnabel contended that these were not the cause of the settlement of the Sears' Building. Instead, it argued that the dewatering process undertaken by the subcontractors caused the resulting settlement damage to the Sears Building. Dewatering was required at the Project because the excavation was thirty-five feet deep with three levels of parking under the building. Without such treatment, the excavation would have filled with water. OMNI hired Division Two, owned by President George King, as the dewatering subcontractor. Dewatering an excavation site can cause settlement because water is removed from the sand stratum of earth. This removal can force the clay level above the sand or gravel to compress and consolidate, resulting in settlement. As a result, dewatering wells have to be properly filtered and screened so that soil material is not pumped out of the excavation. The existing water levels at the site have to be examined to determine whether the lowering of the water level would induce soil consolidation.
Three deep water wells were eventually used at the Project. The controversy surrounded dewatering well # 5 ("DW-5"). After several of the engineering consultants voiced concern about the initial placement of DW-5, it was relocated to approximately twenty-seven feet from the northeast corner of the Brady Building. This placed DW-5 outside and to the east of the sheeting and shoring system. Schnabel contended that the placement of DW-5 was a cause of the settlement because it was so close to the excavation.
After the initial settlement, there were meetings concerning the location of the well and the possible loss of fines (minute particles of soil) from the dewatering process. When fines are pumped out of an excavation, crevices are left between larger chunks of material. Once the fines are pumped, consolidation or compression of the soil results. However there was no evidence which would indicate that fines had been pumped out of the excavation. After an inquiry made by Mr. Forma, SEA arranged for laboratory tests of the water taken from the wells. No presence of fines was found. In a letter dated May 14, 1995, SEA concluded that only minute amounts of fines were lost and advised Westminster that loss of fines was of "no consequence" to the settlement movements which had been observed.
DW-5 was turned off during the last week in August right after the initial settlement and damage to the Sears building. After the second settlement, STS concluded that it was the lateral movement of the soil, not the dewatering process, that was the major cause of the settlement. Furthermore, testimony at the trial showed that settlement related to dewatering operations normally occurs over days and weeks -- not abruptly as in this case. In addition there were no similar settlements at points equidistant from DW-5. If drawdown from the other two wells was the cause of the settlement, it would be expected to cause similar settlements at points which were at equal distances from DW-5 (i.e., settlement points 13 and 15).
Before Schnabel even installed the system, Westminster's consultants Mueser-Rutledge believed that the impact of dewatering would be minimal. In an opinion letter to Westminster on April 23, 1984, Mueser-Rutledge concluded that drawdown due to dewatering was not expected to be a problem because sufficient dewatering had been done previously in the soils in that area during construction of the Washington Metro. It concluded that only a quarter to one-half inch of settlement would result from dewatering. It also advised that the use of steel sheeting would not provide any more protection than the use of soldier piles and wood lagging -- the minimal effect from dewatering would be the same.
From the onset of the Project it was understood by the parties that dewatering would result in settlement of one-eighth to one-quarter inch but that settlement would be uniform and it would not damage the Sears Building. Uniform settlement would not cause damage because the entire building -- at all points -- would move vertically downward at the same time. As expected, settlement of about one-eighth inch had occurred at all monitoring points around the building by August 18th.
In short, then, plaintiff has met its burden on its professional negligence claim. The evidence presented by the plaintiff was sufficient to show that Schnabel failed to meet the standard of care required for subcontractors installing sheeting and shoring systems along the Pennsylvania Avenue corridor. The expert testimony was equally convincing in establishing this standard of care. And as explained in detail above, the plaintiff demonstrated a causal connection between Schnabel's breach of care and the damage to the Sears Building, most specifically by showing how the soldier pile movement and yielding of the tiebacks installed in clay caused the settlement.
Plaintiff also established that Schnabel's negligence was the proximate cause of the damage to the Sears Building. "To establish proximate cause, the plaintiff must present evidence from which a reasonable juror could find that there was a direct and substantial causal relationship between the defendant's breach of the standard of care and the plaintiff's injuries and that the injuries were foreseeable." District of Columbia v. Watkins, 684 A.2d 395, 402 (D.C. 1996)(quoting Psychiatric Inst. of Wash. v. Allen, 509 A.2d 619, 624 (D.C. 1986)). Although the evidence adduced at trial suggested several other factors which may have influenced the settlement of the Sears Building -- including effects from dewatering and regrading the slope -- it is clear that the soldier beam and wood lagging system designed and installed by Schnabel "played a substantial part in bringing about" the settlement and damage to the Sears Building. Sanders v. Wright, 642 A.2d 847, 848 (D.C. 1994). The evidence satisfies plaintiff's burden on proximate cause.
In any event the Subcontract imposes liability for damage to the Sears Building on Schnabel resulting in whole or in part from Schnabel's negligence. Article 6.c. provides:
If, as a result, in whole or in part, of negligence . . . of Subcontractor, his employees, agents, or lower-tier Subcontractors . . . any property is damaged, lost or destroyed, Subcontractor assumes the liability therefor and agrees to hold OMNI . . . and [its] sureties harmless therefor.
Pl. Ex. 47.