Drilling at Millville, New Jersey, at the Bridgeton Pike Well Complex (39°24´16.67''N, 75°05´19.99''W; elevation = 89.7 ft [27.16 m]; Millville quadrangle, Cumberland County) (Fig. F1) began in May 2002. Drilling operations were superintended by Gene Cobbs, USGS EESPT (Don Queen, Drilling Coordinator); Gene Cobbs III was the driller, and Brad A. Huffman was the assistant driller. On 2 May, the EESPT drillers arrived on site and began rigging up and connecting electrical and water hookups. On 2 May, James Browning and Peter Sugarman moved equipment on site and set up a field laboratory in a trailer. A Kodak DC260 digital zoom camera (38.4–115.2 mm lens; 1536 x 1024 megapixel resolution), Macintosh G4, and photography stand were set up to photograph 2-ft (0.61 m) core segments. Camera default settings (including flash) with wide angle (38.4 mm) were used, following procedures established at the Ocean View, New Jersey, drill site (Chap. 2, this volume).
All cores were measured in feet (all depths are given in feet below land surface), and all operations are described in feet only. We continued to adopt ODP convention of top-justifying depths for intervals with incomplete recovery for all field notes and photographs.
The first core was obtained on 4 May 2002 using a Christensen 94-mm (HQ) system. We initially used a CME 4.5-in bit but switched on the second day of drilling to a Christensen 4.25-in bit. For unconsolidated sands, an extended ("snout") shoe was used to contact the sample 1.5–2.5 in ahead of the bit; core diameter was 2.4 in with a rock shoe and 2.1 in with the snout shoe. Approximately 1.5 ft (0.46 m) of large-diameter (10 in) surface casing was set; the large diameter was designed to catch cuttings from reaming a 5-in hole for casing.
Coring commenced on 4 May; the top 1.5 ft (0.46 m) was drilled but not cored. The first four cores (13.5 ft; 4.11 m) between 1.5 and 15 ft (0.46 and 4.57 m; recovery = 76%) were rapidly recovered. The first three cores penetrated sand and gravel from the Bridgeton Formation; from 7.4 to 15.5 ft (2.26 to 4.72 m) the core was mostly coarse to very coarse sand and gravel. At 15 ft (4.57 m), run 5 was cut short (15–15.5 ft; 4.57–4.72 m) because the outer core barrel was clogged with sand. Run 6 was drilled to 20 ft (6.10 m), but only 0.4 ft (1.12 m) was recovered (15.5–15.9 ft; 4.72–4.85 m); the remaining material was washed away. The drillers had trouble with the new experimental (CME 4.5 in) drill bit. The water grooves on the inside of the bit are not deep enough to allow sand to wash through it easily. The bit becomes clogged in the coarse sands encountered at the top of the hole, preventing good recovery. The landing ring wore out, allowing the quad latch to slip through. The drillers halted for the day after run 9 (30–31 ft; 9.14–9.45 m) to replace the landing ring. The day ended with 18.4 ft (5.61 m) recovered from a 29.5-ft run (8.99 m; recovery = 62.4%).
On 5 May, we drilled to 100 ft (30.48 m); 54.85 ft (16.72 m) of core was obtained from 69 ft (21.03 m; recovery = 79.5%) and drilled under ideal weather conditions. We used the new drill bit in the morning, but it continued to block up. At noon, we switched to a 4.25-in Christensen bit and the footage drilled and recovery dramatically improved.
On 6 May, smooth coring continued on run 23 (100–110 ft; 30.48–33.53 m) in interbedded sands and clays. A clay bed was penetrated at 110–113.9 ft (33.53–34.72 m), though sands reappeared at 115.3 ft (35.14 m). We decided not to set casing in this clay but to wait for clays predicted in the lower part of the Wildwood Member of the Kirkwood Formation. Runs were shortened on runs 24–29 (110–140 ft; 33.53–42.67 m) because the core barrel was filled with sand, preventing advancement. Recovery on these runs is greater than computed because the loose sands compress easily. The section became siltier at 150.8 ft (45.96 m), allowing 10-ft (3.05 m) runs with good recovery (runs 31–32, 150–170 ft; 45.72–51.82 m). Recovery was moderate on run 33 (170–180 ft; 51.82–54.86 m) because clay plugged the barrel and the soft sands below were washed away. The day ended at 180 ft (54.86 m), with 50.55 ft recovered (15.41 m; recovery = 63.2%).
On 7 May, no problems were encountered on runs 34–37 (180–204 ft; 54.86–62.18 m). During run 38 (204–210 ft; 62.18–64.01 m), we encountered a lithified zone 0.8 ft (0.24 m) into the run and the rest of the run (204.8–210 ft; 62.42–64.01 m) was lost. Smooth drilling was encountered the rest of the day. We ended at 240 ft (73.15 m) in a coarse sand (upper Atlantic City 800-foot sand aquifer). Recovery for the day was 48.15 ft (14.68 m) from 60 ft drilled (18.29 m; recovery = 80.25%).
On Wednesday, 8 May, we cored 70 ft (21.34 m) with very good recovery (56.85 ft; 17.33 m; recovery = 81.21%) through fine to coarse sands and silty very fine sands. We ended at 310 ft (94.49 m) in clay; the contact of the sand above with the stiff clay below was well preserved at 302.4–303.7 ft (92.17–92.57 m).
On Thursday, 9 May, run 52 (310–320 ft; 94.49–97.54 m) was drilled into clay (9.5 ft [2.90 m] recovered) to check its continuity for casing. The rods were pulled in anticipation of logging and casing.
P. McLaughlin (DGS) obtained downhole and uphole logs to 315 ft (96.01 m) using the DGS Century Geophysical Corporation drawworks and gamma-multipoint electric logging tool (model 8044A). The tool records a gamma log and suite of electric logs, including spontaneous potential (SP), short normal resistivity (16N), long normal resistivity (64N), point resistivity, and lateral resistivity. The downhole log was not useful because of electrical noise from the adjacent pump house and aerator unit. For the uphole log, electrical noise was significantly reduced by using a generator instead of the local electric and by having the drillers fill the hole all the way to the top with water/mud and placing the ground electrode at the mouth of the hole. The only evidence of electrical noise on the up-run log is a resistivity spike around 50 ft (15.24 m); it is possible that the spike around 90 ft (27.43 m) is also noise.
From 10 to 12 May, the hole was reamed twice with a 77/8-in tricone bit, and 5-in (12.7 cm) polyvinyl chloride (PVC) (schedule 80) casing was set to 308 ft (93.88 m) to be removed upon completion. No problems were encountered in setting casing.
Coring resumed on 13 May. Runs 53 and 54 (320–340 ft; 97.54–103.63 m) recovered 9.95 and 8.5 ft (3.03 and 2.59 m), respectively. No core was initially recovered on run 55 (340–350 ft; 103.63–106.68 m). We went down two more times to recover the lost core; only 0.4 ft (0.12 m) was recovered. During run 56 (350–355 ft; 106.68–108.20 m), we drilled 5 ft (1.52 m), again with poor recovery (0.4 ft; 0.12 m). We pulled the rods. With core recovered the next day from 340 to 350 ft (103.63–106.68 m), we recovered 19.25 ft (5.87 m) from 35 ft drilled (10.67 m; recovery = 55%).
On 14 May, the drillers recovered 3.3 ft (1.01 m) that had lodged itself in the outer core barrel. This solid core probably came from 340–350 ft (103.63–106.68 m) and is designated Core 56A. The 0.5-ft (0.15 m) core from 340.0–340.5 ft (103.63–103.78 m) may have blocked the barrel; the core was left sticking out of the bottom of hole (BOH) and was pushed aside during run 56 (350–355 ft; 106.68–108.20 m). Alternatively, the core may have come from 350.5–355 ft (106.68–108.20 m). The next run (run 57: 355–359 ft; 108.20–109.42 m) on 14 May recovered 3.1 ft (0.94 m) of core; the very top to 0.2 ft (0.06 m) is a solid glauconitic clay that may be out of place (?overturned), whereas the subsequent 0.2–0.7 ft (6–21 cm) is slurry underlain by a slightly micaceous shelly silty clay (355.7–358.1 ft; 108.42–109.15 m). This suggests that we missed a sequence boundary between the glauconitic clay and the silty clay. Smooth coring with over 100% recovery in expanding silty clays continued during runs 58–59 (359–379 ft; 109.42–115.52 m). Only 7 ft (2.13 m) was recovered during run 60 (379–389 ft; 115.52–118.57 m) as a tight, waxy clay hindered recovery. The lost clay was chewed up and injected into the top 0.3 ft (0.09 m) of the next core (389–400 ft; 118.57–121.92 m). During this run, clays interbedded with silty clays resulted in changes from high (400 lb) to moderate (200 lb) mud pressures during the first 7–8 ft (2.13–2.44 m) of the run, which caused a thick rind; the bottom 3–4 ft (0.91–1.22 m) had uniform pressures (200 lb) and no rinds as we penetrated silty clays. Smooth coring continued during the last two runs (runs 62–63: 400–420 ft; 121.92–128.02 m), even though we penetrated various clay and sand lithologies. Recovery for the day was 59 ft (17.98 m) from 65 ft drilled (19.81 m; recovery = 91%).
On 15 May, 10.1 ft (3.08 m) was recovered during run 64 (420–430 ft; 128.02–131.06 m). During run 65 (430–440 ft; 131.06–134.11 m), the core barrel came up empty and the drillers found the teeth had broken off the shoe. The drillers went back down to try and catch the core again; they recovered only 0.6 ft (0.18 m). Good recovery resumed between 440 and 490 ft (134.11 and 149.35 m) during runs 66–70. Drilling ended for the day at 490 ft (149.35 m) with 55.25 ft (16.84 m) recovered from 70 ft drilled (21.34 m; recovery = 79%).
On 16 May, smooth coring continued in clayey glauconitic quartz sands, with full recovery during runs 71–75 (490–540 ft; 149.35–164.59 m). During run 76 (540–550 ft; 164.59–167.64 m), we chewed up the bottom 1.5 ft (0.46 m) and discarded 0.3 ft (0.09 m) of chewed core from the top of this run, yielding 8.3 ft (2.53 m) of recovery. The next core was stopped 5 ft (1.52 m) into the run, as the lithology appeared to change to coarser sands that we wanted to avoid blowing away; 4.9 ft (1.49 m) was recovered. Run 78 (555–556 ft; 169.16–169.47 m) recovered 5.8 ft (1.77 m) of solid core; we have no explanation for this over-recovery in the sands except expansion. The last run (run 79: 560–570 ft; 170.69–173.74 m) recovered 8.9 ft (2.71 m). The day ended with 81.2 ft (24.75 m) recovered from 80 ft drilled (24.38 m; recovery = 101.5%).
During the morning of 17 May, drilling continued smoothly through glauconitic quartz sand (runs 80–82: 570–600 ft; 173.74–182.88 m). Mud pressures increased in the lower 3 ft (0.91 m) of run 83 (600–610 ft; 182.88–185.93 m). Gravel or hard material was encountered but not recovered in the bottom part of run 84 (610–620 ft; 185.93–188.98 m). During Run 85, the driller sensed recovery problems and stopped after 5 ft (1.52 m [620–625 ft; 188.98–190.50 m]). Only 0.5 ft (0.15 m) was recovered. The hard silty sand lithology caused the end of the shoe to flare out. Run 86 drilled the next 5 ft (1.52 m [625–630 ft; 190.50–192.02 m]) with excellent recovery, and two subsequent core runs (87 and 88: 630–640 and 640–650 ft; 192.02–195.07 and 195.07–198.12 m, respectively) went smoothly overall, with the exception of high (700 psi) mud pressure in the upper part of run 87. Out of 80 ft (24.38 m) drilled for the day, 69.8 ft was recovered (21.28 m; recovery = 87%).
On 18 May, rainy and very windy weather hindered operations. The rain cleared by noon, though cold and windy conditions prevailed. The drill crew began by running back 40 ft (12.12 m) of rods they pulled the previous day. This shaved the hole and helped prevent the inner core barrel from sticking in the hole. An empty core barrel was retrieved on the third try; effectively 1 ft (0.30 m) was drilled from 650 to 651 ft (198.12 to 198.42 m). Runs 90 (651–657.5 ft; 198.42–200.41 m) and 91 (657.5–665 ft; 200.41–202.69 m) recovered 6.5 and 7.2 ft (1.98 and 2.19 m), respectively. The day ended with 5.45 ft (1.66 m) recovered from a 5-ft run (1.52 m [665–670 ft; 202.69–204.22 m]), yielding 19.15 ft (5.84 m) recovered from 20 ft (6.10 m) drilled for the day (recovery = 96%).
On 19 May, drilling slowed because of the semilithified nature of the Shark River Formation. Recovery was good between 670 and 675 ft (204.22 and 205.74 m) during run 93, although drilling was slow. From 675 to 680 ft (205.74 to 207.26 m), drilling was still slow; 3.3 ft (1.01 m) was recovered; and the lower part of the core was lithified (porcellanite?). There was excellent recovery during run 95 (680–684 ft; 207.26–208.48 m; 3.7 ft [1.13 m] recovered), although drilling was difficult because of changing lithologies from silt to clay and variable degrees of consolidation of the sediment. The core was chewed between 684 and 694 ft (208.48 and 211.53 m), although recovery was 10.1 ft (3.08 m). Runs 97–99 (694–720 ft; 211.53–219.46 m) recovered 5.0, 10.7, and 9.85 ft (1.52, 3.26, and 3.00 m), respectively. The day ended with 47.35 ft (14.43 m) recovered from 50 ft drilled (15.24 m; recovery = 94.7%).
On 20 May, run 100 (720–730 ft; 219.46 m) had poor recovery because of porcellanite beds; 3.4 ft (1.04 m) was recovered. Run 101 (730–740 ft; 222.50–225.55 m) recovered 4.25 ft (1.30 m); the lower part of the core apparently slipped out of the core catcher. Run 102 was a 5-ft (1.52 m) run from 740 to 745 ft (225.55 to 227.08 m), with 5.8 ft (1.77 m) recovered; the extra 0.8 ft (0.24 m) recovered was placed between 739.2 and 740 ft (225.31 and 225.55 m). Run 103 (745–754 ft; 227.08–229.82 m) was stopped at 9 ft (2.74 m). Run 104 (754–760 ft; 229.82–231.65 m) was 6 ft (1.83 m) to even out the run depths, recovering 5.4 ft (1.65 m). Run 105 (760–770 ft; 231.65–234.70 m) recovered 9.8 ft (2.99 m) of core. For the day, 37.95 ft (11.57 m) was recovered from 50 ft drilled (15.24 m; recovery = 76%).
On the morning of 21 May, the rods were stuck in the hole and it took the drillers 3 hr to loosen them. Coring the Manasquan Formation was slow. The first core (run 106) was up at 1130 hr. During run 107 (780–790 ft; 237.74–240.79 m), the core slipped out of the inner core barrel while it was being pulled. The drillers went back down after the core and were able to retrieve 6.95 ft (2.12 m). Runs 108 (790–797.5 ft; 240.79–243.08 m) and 109 (797.5–803 ft; 243.08–244.75 m) recovered 8 and 4.5 ft (2.44 and 1.37 m), respectively; the former probably includes ~0.5 ft (0.15 m) from the previous run. Out of 33 ft (10.06 m) drilled, 27.1 ft (8.26 m) was recovered (recovery = 82%). The drillers pulled 160 ft (48.77 m) of rods for the night.
One 22 May, the rods barely turned; we ran the inner core barrel and lowered 160 ft (48.77 m) to prepare for coring. Run 110 (803–806 ft; 244.75–24.38 m) recovered 7 ft (2.13 m) of slurry, 2 ft (0.61 m) of mixed core and slurry that was discarded, and 1.25 ft (0.38 m) of apparently solid core. We discussed whether the top 1.0 ft (0.30 m) of this 1.25-ft (0.38 m) segment was solid or intruded by mud because it appeared different from the tight clays at the base (bottom 0.25 ft; 8 cm) of the run. Careful slicing of the core shows it to be a solid core. During run 111 (806–810 ft; 245.67–246.89 m), we left 3 ft (0.91 m) of core in the hole. During run 112 (810–816 ft; 246.89–248.72 m), the barrel filled 6 ft (1.83 m) into the run; the core contained 7.2 ft (2.19 m) of solid core and 3 ft (0.91 m) of ground-up core that was discarded. There was a natural break in the core at 1.8 ft (0.55 m); this was added to run 111 and the rest (5.4 ft; 1.65 m) to run 112. The heavy rind washed easily off of the core, revealing a laminated to massive foraminiferal clay. Personnel from the USGS Water Resources Division sampled from 810.0 to 811.0 ft (246.89 to 247.19 m) (two samples, 0.7 ft [0.21 m] for pore squeezing and 0.3 ft [0.09 m] for microbiology). During run 113 (816–820 ft; 248.72–249.94 m), we recovered 5.2 ft (1.58 m) of core. The total recovery from runs 111–113 (806–820 ft; 245.67–249.94 m) was thus 13 ft (3.96 m), and the core depths should probably be recomputed for high-resolution studies assuming near total recovery for this interval. Run 114 (820–830 ft; 249.94–252.98 m) recovered 8.15 ft (2.48 m), but run 115 (830–840 ft; 252.98–256.03 m) only recovered 0.5 ft (0.15 m), ending the day with 23.30 ft (7.10 m) recovered from 37 ft drilled (11.28 m; recovery = 62.97%). We lost circulation at the end of run 115. The drillers swabbed the hole at the end of the run by pulling up and lowering the rods 5 ft (1.52 m); on the first swab, pressure ran very high, suggesting that we recut/blew away the core that had either slipped out or not broken off. The drillers pulled 200 ft (60.96 m) off the bottom for the night to avoid getting stuck in the swelling Manasquan clays.
On 23 May, we recovered 3.9 ft (1.19 m) of core from the previous day; it was chewed up in sections. We placed this core in the interval from 831 to 834.9 ft (253.29 to 254.48 m), although we are unsure of its precise location. Drilling became easier during the next few runs with excellent recovery as we penetrated the Vincentown Formation clays. The day ended at 890 ft (271.27 m), with 50.1 ft (15.27 m) recovered (recovery = 100%). The drillers pulled up 160 ft (48.77 m) overnight to avoid being trapped by the swelling Manasquan clays.
On 24 May, the drillers had great difficulty getting to the BOH. Swelling clay in the upper part of the Vincentown Formation equivalent prevented hole entry beginning at 847 ft (258.17 m); we recut the hole with difficulty, particularly near 870 ft (265.18 m). This is this same lithologic interval that caused diversion of the rods at Ancora, New Jersey, at 543 ft (165.51 m) causing us to start coring Hole B there. We were concerned that we had to penetrate below these clays into the glauconitic quartzose sandy clays of the lower part of the Vincentown equivalent before reaming the hole. We reached the BOH at 1130 hr and pulled the inner core barrel. It was filled with slurry and 3.95 ft (1.20 m) of solid core obtained somewhere between 847 and 890 ft (258.17 and 271.27 m). This was saved for demonstration/classroom studies. The bottom 0.2 ft (0.06 m) probably came from the BOH; it contained a solid clay similar to the lithology from the last run. Drilling was faster (20 min) during run 121 (890–900 ft; 271.27–274.32 m) and we had full recovery (10.65 ft; 3.25 m), though we had to remove a thick rind from clays above 899.25 ft (274.09 m). We penetrated glauconitic clays at the base of the run that lacked the rind. Smooth, moderately slow drilling during runs 122 (900–910 ft; 274.32–277.37 m) and 123 (910–920 ft; 277.37–280.42 m) recovered 10.5 and 10.3 ft (3.20 and 3.14 m), respectively, in glauconitic clays, yielding 31.45 ft (9.59 m) recovered from 30 ft (9.14 m) drilled for the day (recovery = 105%).
The drillers went to Reston, Virginia, on Saturday and returned on Sunday. They reamed the hole using a 43/4-in diameter tricone roller bit to alleviate swelling of the clays in the lower Shark River, Manasquan, and Vincentown Formations. At ~880 ft (268.22 m), we started drilling a new hole as the swelling clays diverted the rods as they did at Ancora. The hole was drilled without coring down to 908 ft (276.76 m). Runs 124 (908–910 ft; 276.76–277.37 m) and 125 (910–920 ft; 277.37–280.42 m) contained 2.6 and 10.25 ft (0.79 and 3.12 m) of solid core, respectively. Therefore, we double-cored the interval from 908 to 920 ft (276.76 to 280.42 m). The second cores from this interval were marked with "B" to distinguish them from the original 908–920 ft (276.76–280.42 m). Coring was excellent for the day. We ended at 937.7 ft (285.81 m). For the day, 30.95 ft (9.43 m) was recovered from 29.5 ft drilled (8.99 m; recovery = 105%).
On 30 May, we cored 2.5 ft (0.76 m) during run 128 (937.5–940 ft; 285.75–286.51 m), resuming 10-ft (3.05 m) cores during run 129 with full recovery. Run 130 (950–957.5 ft; 289.56–291.85 m) was pulled up short because slurry filled the top 2.5 ft (0.76 m) of the barrel. Run 131 finished the rod to 960 ft (292.61 m) with full recovery. Run 132 (960–970 ft; 292.61–295.66 m) also had full recovery. We ended at 980 ft (298.70 m) with 42.5 ft (12.95 m) recovered from 42.5 ft drilled (12.95 m; recovery = 100%).
On 31 May, run 134 (980–985 ft; 298.70–300.23 m) recovered 5.2 ft (1.58 m) that includes the K/P boundary. Run 135 (985–995 ft; 300.23–303.28 m) recovered 10.4 ft (3.17 m). A 5-ft (1.52 m) run finished the rod from 995 to 1000 ft (303.28 to 304.80 m), with 4.7 ft (1.43 m) of recovery. The next run from 1000 to 1010 ft (304.80 to 307.85 m) had excellent recovery of 10.2 ft (3.11 m). On the final run of the day, from 1010 to 1020 ft (307.85 to 310.90 m), 5.1 ft (1.55 m) was recovered. We recovered 36.9 ft (11.25 m) from 40 ft drilled (12.19 m; recovery = 92.3%) for the day.
On 1 June, the drillers recored the bottom of the last run from the previous day and recovered an additional 1.3 ft (run 138A; 0.40 m). This makes a total recovery of 36.9 ft (11.25 m) for the 40-ft (12.19 m) interval between 980 and 1020 (298.70 and 310.90 m), or 92.25% recovery. The five subsequent runs made on 1 June all went smoothly and had excellent recovery. Run 139 recovered 9.1 ft (2.77 m) from the 1020 to 1030 ft (310.90 to 313.94 m) interval. Run 140 encountered harder drilling during the run and recovered 10.2 ft (3.11 m) from 1030 to 1040 ft (313.94 to 316.99 m). Runs 141 (1040–1050 ft; 316.99–320.04 m) and 142 (1050–1060 ft; 320.04–323.09 m) recovered 9.9 ft and 10.1 ft (3.02 m and 3.08 m), respectively. Run 143, the final run of the day, from 1060 to 1070 ft (323.09 to 326.14 m) was drilled quickly. The day ended with 48.9 ft (14.90 m) recovered of 50.0 ft drilled (15.24 m; recovery = 97.8%).
No problems were encountered on 2 June, the last day of drilling with HQ core. The day ended with 29.05 ft (8.85 m) recovered of 30 ft (9.14 m) drilled (recovery = 97%). Of 1100 ft (335.28 m) of HQ cored, we recovered 951.35 ft (289.97 m; recovery = 86%). The rods were pulled in anticipation of logging on 4 June.
On 4 June, P. McLaughlin (DGS) obtained a series of open-hole geophysical logs using the DGS Century Geophysical Corporation drawworks and logging tools. The gamma-multipoint electric logging tool (model 8044A) was run seven times in attempts to reduce major problems with electrical interference on the electric logs related to power lines and equipment at the water treatment facility; none of the runs were entirely satisfactory. The deepest of the runs reached 928 ft (282.85 m) depth. The electric logging was followed by two runs (down and up) of the gamma-induction tool to 925 ft (281.94 m) depth. The magnetic-induction sensors allowed calculation of a resistivity log that was not affected by electrical interference as were the logs obtained with the electrical resistivity tool.
The drillers returned to Reston, Virginia, loaded pipe onto the trailer, and returned to New Jersey on Saturday, 8 June. Coring resumed using a Christensen CNWL (NQ) system that produces a 3.162 in (8.03 cm) hole diameter and cuts 1.875-in (4.76 cm) diameter cores with a rock shoe and 1.67-in in (4.24 cm) diameter cores with an extended shoe. The hole was blocked by swelling clays of the Manasquan and Vincentown Formations beginning at 800 ft (243.84 m). We pulled the rods and rereamed the hole with a 43/4-in diameter tricone roller bit. The drillers began to rerun the rods on 12 June. On 13 June, we began to recore the bottom 50 ft (15.24 m) of the hole into which material had caved. At 1070 ft (326.14 m), the drillers realized that the bit had started a new hole. The three runs from 1070 to 1100 ft (326.14 to 335.28 m) cored in this new hole are referred to Hole B. Heavy rains started at 1515 hr, and the drillers decided to quit for the day because we were to 1100 ft (335.28 m), the equivalent of the base of the HQ hole. We ended with 18.6 ft (5.67 m) recovered from the 30 ft (9.14 m) cored again (recovery = 62%).
Swelling kaolinitic clays in the Paleocene/Eocene (P/E) boundary interval at 880 ft (268.22 m) proved to be the bane of maintaining a stable, open hole. Despite having reamed these clays with a 43/4-in diameter tricone roller bit over the Memorial Day weekend, by 12 June the diameter of the hole had become narrower than the NQ rods (2.875 in). These clays may have been responsible for problems at Bass River and not the caving sands. We discussed two options for future drilling through the P/E boundary: (1) using larger casing at the top so we could use a larger reaming bit and (2) casing off the clays.
Normal coring operations in a stable hole continued in the NQ hole on 14 June. Run 150 (1100–1110 ft; 335.28–338.33 m) only recovered 2.1 ft (0.64 m), as a pyrite nodule blocked the shoe, and soft silty clays below were blown away. Smooth coring on runs 151 and 152 (1110–1130 ft; 338.33–344.42 m) provided full recovery. Heavy rain delayed operations 1 hr. On the next run, the core barrel would not go down the hole; we suspected that one rod may have been bent. We switched core barrels and got the inner barrel to latch in. As we were preparing to add rod to resume drilling, we found that the rods would not turn. We circulated mud and freed the rods and had full recovery on run 153 (1130–1140 ft; 344.42–347.47 m). We ended the day with 32.5 ft (9.91 m) recovered from 40 ft drilled (12.19 m; recovery = 81%).
On 15 June, 102% was recovered on run 154 (1140–1150 ft; 347.47–350.52 m). Run 155 (1150–1160 ft; 350.52–353.57 m) also had perfect recovery of 104%. Run 156 (1160–1170 ft; 353.57–356.62 m) recovered 4.7 ft (1.43 m). The core dropped out of the inner barrel, and we were unable to recover it. On runs 157 (1170–1180 ft; 356.62–359.66 m) and 158 (1180–1190 ft; 359.66–362.71 m), 10.25 and 7.6 ft (3.12 and 2.32 m) of core was recovered, respectively. Recovery for the day was 43.15 ft (13.15 m) from 50 ft drilled (15.24 m; recovery = 86%).
The first two cores on 16 June (1190–1210 ft; 362.71–368.81 m) came up without incident. After drilling run 161 (1210–1220 ft; 368.81–371.86 m), clays behind the quad latch prevented the drillers from retrieving the inner core barrel. Additional mud circulation eventually cleaned the quad latch, allowing drilling to continue. No further difficulties were encountered. The day ended with 51.9 ft (15.82 m) recovered from 50 ft drilled (15.24 m; recovery = 104%).
On 17 June, we began with a 5-ft (1.52 m) run from 1240 to 1245 ft (377.95 to 379.48 m), of which 4.6 ft (1.40 m) was recovered. During run 165 (1245–1250 ft; 379.48–381.00 m), we recovered 5.9 ft (1.80 m); some of this interval is probably material missed above. Run 166 (1250–1260 ft; 381.00–384.05 m) had 7.9 ft (2.41 m) of recovery and ended in clay. Run 167 (1260–1270 ft; 384.05–387.10 m) recovered 3.2 ft (0.98 m) of core. There was a problem dropping the core barrel down on the next run. Run 168 (1270–1280 ft; 387.10–390.14 m) recovered 10.4 ft (3.17 m). The day ended with 32 ft (9.75 m) recovered from 40 ft drilled (12.19 m; recovery = 80%).
On 18 June, runs 169 and 170 (1280–1292 ft; 390.14–393.80 m) had to be cut short because of hard layers. Run 171 (1292–1300 ft; 393.80–396.24 m) recovered only 0.2 ft (0.06 m) of indurated sand because the hard layer broke the shoe. The drillers believe the material that was not recovered under the indurated layer was sand. Run 172 recovered only 1.7 ft (0.52 m) from a 10-ft (3.05 m) run (1300–1310 ft; 396.24–399.29 m). The drillers were not sure that the inner core barrel latched in properly. The drillers had to cut off ~300 ft (91.44 m) of frayed cable before starting the next run. Run 173 (1310–1318.5 ft; 399.29–401.88 m) was cut short at a shell layer. The day ended with 22.65 ft (6.90 m) recovered from 38.5 ft drilled (11.73 m; recovery = 58.8%).
On 19 June, run 174 finished the rod with 1.2 ft (0.37 m) recovered from 1.5 ft (0.46 m) drilled. Run 175 (1320–1330 ft; 402.34–405.38 m) recovered 6.15 ft (1.87 m) with high, variable mud pressures (up to 1000 psi); the core cleaned well, though some interbeds still had minor intrusions of drilling mud. Shells hindered recovery during run 176 (1330–1340 ft; 405.38–408.43 m), with high, variable pressures, blowing away the bottom 6.7 ft (2.04 m). Hard drilling during run 177 (1340–1350 ft; 408.43–411.48 m) yielded 8.1 ft (2.47 m) of recovery. Run 178 (1350–1360 ft; 411.48–414.53 m) yielded 10.55 ft (3.22 m), for a total recovery for the day of 29.25 ft (8.92 m) from 41.5 ft drilled (12.65 m; recovery = 70%).
On 20 June, run 179 (1360–1365 ft; 414.53–416.05 m) slipped out of the inner core barrel as the drillers were retrieving it. They drilled 5 more ft (1.52 m; 1365–1370 ft; 416.05–417.58 m) and brought up both cores together. This is logged as a single run (run 179; 1360–1370 ft; 414.53–417.58 m). Runs 180 (1370–1380 ft; 417.58–420.62 m) and 181 (1380–1390 ft; 420.62–423.67 m) recovered 9 ft and 7.75 ft (2.74 and 2.36 m), respectively. Run 182 (1390–1400 ft; 423.67–426.72 m) recovered 4.4 ft (1.34 m) after hitting a siltstone. The day ended with 27.1 ft (8.26 m) recovered from 40 ft drilled (12.19 m; recovery = 67.8%).
On 21 June, the rods were stuck and several hours were spent freeing them. During run 183 (1400–1410 ft; 426.72–429.77 m), only 0.65 ft (0.20 m) of 10 ft (3.05 m) was recovered; the recovered lithology was a sandstone that clogged the core barrel. During run 184 (1410–1420 ft; 429.77–432.82 m), 6.8 ft (2.07 m) was recovered. There was a thin siltstone at the bottom of the core that probably clogged the barrel, limiting complete recovery. Run 185 (1420–1430 ft; 432.82–435.86 m) recovered 9.2 ft (2.80 m). Recovery during run 186 (1430–1435 ft; 435.86–437.39 m) was 100%. After the final run, the drillers did not have enough cable on the winch for the overshot device to reach the inner barrel, so they raised the drill bit to ~1400 ft (426.72 m) before sending the overshot down. The day ended with a recovery rate of 54%. The drillers raised the rods 220 ft (67.06 m) at the end of the day in the hope of reducing problems with stuck rods in the morning.
On 22 June, the rods again stuck briefly at the beginning of the day. The drilling was again modified to accommodate the short cable on the winch for the overshot. At the end of each run, the bottom of the drill string was raised to between 1400 and 1420 ft (426.72 and 432.82 m) before sending down the overshot device to retrieve the inner barrel. After retrieving the core, the inner barrel was sent back down, latched in place, and the string lowered from ~1400 to 1420 ft (426.72 to 432.82 m) to BOH to resume drilling. Run 187 (1435–1440 ft; 437.39–438.91 m) started the day with a recovery of 1.65 ft (0.50 m). This set the tone for a day where hard zones in the section created coring problems. Core recovery was often incomplete, and cores were often worn down to a thin, twisted remnant. Run 188 (1440–1450 ft; 438.91–441.96 m) recovered 2.65 ft (0.81 m). Run 189 only ran 2 ft (0.61 m), stopping at 1452 ft (442.57 m) where a hard zone was encountered; it recovered 2.15 ft (0.66 m). Run 190 (1452–1460 ft; 442.57–445.01 m) finished off the rod begun on the previous run, recovering 2.3 ft (0.70 m). The final run of the day, run 191 (1460–1470 ft; 445.01–448.06 m), recovered 2.1 ft (0.64 m) due to the problems created by hard concretions. Total recovery for the day was 10.85 ft (3.31 m) of 30 ft (9.14 m) drilled, for 31% recovery. At the end of the day, 260 ft (79.25 m) of drill string was removed to raise the bottom of the string above sticky clays.
On the morning of 23 June, the drill string was again stuck in the hole. The cuttings indicated that the rods were sticking in the Manasquan Formation. The drillers regained circulation at 0855 hr and got the rods back to the BOH by 1015 hr. The first run came up at 1130 hr. No complications were experienced the rest of the day. The day ended with 14 ft (4.27 m) recovered from 30 ft drilled (9.14 m; recovery = 46.2%), leaving the BOH at the target depth of 1500 ft (457.20 m). The drillers pulled 400 ft (121.92 m) from the BOH overnight.
On 24 June, the rods were run back to 1500 ft (457.20 m); we pumped and rotated, thinning the mud to 8.5 lb for logging. S. Curtin (USGS) and P. McLaughlin (DGS) obtained a series of geophysical logs from the hole using the USGS Annapolis, Maryland, Water Resources Division Century Geophysical Corporation drawworks with USGS and DGS Century Geophysical Corporation logging tools. Gamma logs were obtained to 1491 ft (454.46 m) from inside the drill rods for both downhole and uphole runs using the DGS Century slim-line gamma tool (model 9012A). Following logging, the rods were pulled. When all rods were out of the hole, open-hole logging was conducted using the USGS Geophysical Corporation gamma-multipoint electric logging tool (model 8043A); downhole and uphole runs were made to 1496 ft (455.98 m) depth. The resistivity logs obtained were affected by electrical noise related to power lines and equipment at the water treatment facility, especially on the downhole run (shifts at 410–420 ft [124.94–128.02 m] and 820–840 ft [249.94–256.03 m]). A second suite of open-hole logs was obtained with the DGS Century Geophysical Corporation gamma-induction tool; downhole and uphole runs reached 1497 ft (456.29 m) depth. The magnetic-induction sensors allowed calculation of a resistivity log that was not affected by electrical interference as were the logs obtained with the electrical resistivity tool.
On 25 June, the PVC casing was removed and the hole grouted with 22 bags of concrete, plugged, and abandoned. The USGS drillers returned to Reston, Virginia and we bid Gene Cobbs a fond retirement.
Careful comparison among logging runs and matching logging signature to core lithology indicated that there are offsets due to registry problems on the USGS winch. We constructed a composite log consisting of (1) the HQ log taken with the DGS winch shifted down 1 ft (0.30 m) for 0–90 ft (0–27.43 m) and (2) the induction tool log shifted up 4 ft (1.22 m) for 905 ft (275.84 m) to BOH. The logs were spliced just below an increase in the HQ log at ~905 ft (275.84 m).
At Millville, we recovered 1254.85 ft (382.48 m) from a total depth of 1500 ft (457.2 m) drilled and had a recovery of 83.7% for the 1495 ft (455.68 m) cored; median recovery was 90%. Lithologies were described on site and subsequently at the Rutgers University core facility; these descriptions form the basis for the preliminary lithologic descriptions. Cores were cut into 2-ft (0.61 m) sections, labeled at top and bottom of each section, placed into split PVC pipe (3 in diameter), wrapped in plastic sheeting, and stored in 2-ft (0.61 m) NQ wax boxes. A total of 176 core boxes were moved to permanent storage at the Rutgers University core library for further study. Cores were sampled at ~5 ft (1.52 m) intervals for planktonic foraminiferal, calcareous nannofossil, palynology, dinocyst, and diatom biostratigraphy and coarse-fraction lithologic studies at the Rutgers University core library.