The Chief Scientist has three primary roles pertaining to the CPL:
1. To assure the safety and morale of the CPL personnel.
2. To assure that the objectives of the CPL are attained. These include, but are not limited to:
- A. Assuring the highest quality core possible under the conditions at the time.
- B. Assuring that the core temperature is maintained below -15°C at all times.
- C. Responding to (and implementing as appropriate) suggestions made by CPL personnel for improving either core quality or core processing efficiency/ease.
- D. Assuring the accuracy of sampling and the accuracy and completeness of data recording.
- E. Coordinating and integrating the activities of the CPL with drilling activities and the rest of camp.
- F. Resolving any conflicts that arise in the CPL.
3. To monitor and approve all changes to the approved sampling plan.
The Data Manager supports and implements the Chief Scientist’s direction in sampling activities, data recording, and administrative needs. He/she should consult with the Chief Scientist on all significant changes in sampling procedure, all sampling changes, data problems and implement goals and changes directed by the Chief Scientist and produces reports on sampling for distribution.
The Data Manager implements and supervises the data collection, informs CPL personnel of the approved sampling plan, and produces and distributes data reports as necessary. He/she enters data into the database, insures that all data are accurate, and are adequately backed up, and provides information for the Chief Scientist regarding the status of sampling, availability of core, etc. Further the Data Manager should act as an additional conduit for the flow of information, requests, and difficulties to the Chief Scientist, and is responsible for bringing deviations from the sampling plan to the attention of the Chief Scientist.
The Data Manager is also responsible for maintaining the SMO computers, the on-site network, and SMO office supplies.
The CPL Manager supports and implements the Chief Scientist’s direction in the CPL. He/she should consult with the Chief Scientist on all significant changes in CPL procedure, all sampling changes, and implement CPL changes directed by the Chief Scientist.
The CPL Manager supervises the daily operation of the CPL and insures the smooth operation of the CPL equipment. He/she provides information to the Chief Scientist regarding the status of CPL functioning, efficiency, problems, etc. Further, the CPL Manager should act as an additional conduit for the flow of information, requests, and difficulties to the Chief Scientist, and is responsible for bringing difficulties in attaining the goals of the CPL to the attention of the Chief Scientist
The CPL manager also operates the wing slabbing saw, maintains the CPL, saws, tools, and equipment, and coordinates CPL personnel.
The Core Handlers operate in the Dome, in the Feeder Trench, and in the Relaxation Trench. When the drillers have a section of core coming to the surface, all Core Handlers should be in the dome working to process the core and get it below as quickly and as carefully as possible while processing it accurately. Since the drill dome may be quite warm, accurately processing the core and getting it safely below, where it is cooler, will be an important job and require coordination and attention.
Drill Dome Tasks
While a section of core is not being processed in the dome, only one Core Handler will need to be in the trench organizing materials, and preparing for the next section. All Core Handlers will have ear-mic radios and thus will be able to communicate with drillers and each other to coordinate their tasks. Note that the radio communications that the Core Handlers will be using will be the same one as the drillers. The drillers use the radios to coordinate their work, which often involves delicate maneuvering of large, heavy drill parts near hands and fingers. It is critical that the Core Handlers understand this, and not interfere with drillers communications.
The main tasks of the Core Handlers in the drill dome are as follows:
- While the core is traveling to the surface, fill out the Drill Dome Data Sheet. This includes: the date, the time the core was broken from the bottom of the bore hole, the drill run number, the run length as measured by the drill operator, the time the core reached the surface, the length of the core that is retrieved, the dome temperature, the time the core is sent to the trenches, and any pertinent notes.
The core length measured by the Core Handlers should be determined by the sum of the measured lengths of the pieces of core for each run, including any implied gaps.
The only information that should be recorded on the drill dome data sheet while the core is actually being processed is the core length measurements, and any notes that must be written down at the time. All the other information should be recorded either while the core is traveling to the surface, or is on its way to the trenches.
- Cutting the Core. The core will be extruded from the core barrel. The core should be cut at exactly the 2.000 meter mark, whenever there is not a break in the core within 2 cm of the 2.000 meter mark. These cuts are very important as they set the depth scale for the core. They must be done carefully and accurately. Accuracy of at least 0.5 cm should be maintained. If a cut is made at other than the 2.000-meter mark, or a break within 2-cm of the 2.000-meter mark is used in place of a cut, this must be recorded on the top of the core card at the time the cut is made.
- Every 10 meters an 11 cm physical properties sample needs to be cut. A list of where these samples are to be cut will be provided by the Data Manager. The Core handlers should communicate with the physical properties personnel in the trench 10 - 15 minutes before the sample is to be cut so they can be in the dome to pick the sample up. The physical properties personnel should mark the core card indicating the sample that has been removed.
The physical properties personnel may either collect the 11 cm sample in the drill dome, or in the Feeder Trench after the core has been lowered. The latter will reduce traffic in the dome. Where the sample is collected can be determined on site.
- A sample will be collected for helium analysis in the drill dome. Because of the rapid rates of diffusion for helium, these samples must be taken as soon as possible after the core is extruded from the drill. These samples may take the form of a large chip or chunk or may have to be cut off with a saw. The actual sample is on the order of 3x3 cm. Core Handlers should coordinate their activities with the person collecting the helium sample.
- The core should be wiped down with towels to remove most of the nBA from the core as it is moved to the core elevator. The nBA was found to evaporate quite readily, and wiping is intended to assist this process.
- Each time a core section is cut to 2 meters, a new Core Card is started. Core cards are pre-printed with the meter depths and tube numbers. Since every meter of core gets one core card, there will be two core cards for each 2-meter section cut in the drill dome.
In the dome the only information that should be recorded on the core cards is the drill run number. Core handlers should use the measured length of the core to determine how many core cards to take with them to the trench. These cards should have the run number written on them immediately. It is very important that this information be put on each Core Card used each run. If a core tray is only partially filled by a run, the number of the run that completes the meter should also be recorded.
- Each separate piece of core should be marked with 2 arrows indicating up as shown in the diagram below (2 more arrows should be made once in the trenches below). Also, since the physical properties sample cannot be re-oriented with the rest of the core (it is trimmed to square for analysis), 3 pairs of registration marks should be made across the location of the cut before it is made. This will allow re-orientation when the piece is returned to the CPL.
Remember: arrows point up.
The rails that take the core from the drill barrel will be arranged such that the top/bottom orientation of the core cannot be confused, however, care must always be taken to insure that no confusion is introduced, and the orientation is always maintained.
- The entire run of core should be processed, with each 2 meter section being placed in the core elevator as soon as it has been cut and had its core card noted and attached. When all the core from a given run is in the elevator, all the core should be sent below at once. This entire process, from the time the core reaches the surface to the time it is lowered into the feeder trench, takes on average 45 minutes. One goal of the Core Handlers is minimizing this time, particularly if the drill dome temperature is close to or above -15°C, without compromising the accuracy of the measurements made and the care given the core handling.
Once the core is below, the temperature concern should be diminished since it is expected that the Feeder Trench (the trench from core elevator to the freezer) should remain below -15° C all the time. If the Feeder Trench is not below -15° C, the core sections must be taken to the freezer immediately. The core cards and other tasks should be completed when temperatures are lower, perhaps when the core is moved to the relaxation trench.
Under normal conditions (temp < -15° C), the following tasks are to be completed in the trenches:
Preparing Core for the CPL
- Inspect the core sections and complete the core cards. This will include: choosing a core quality category for the "Feeder Trench Quality" section (use definitions noted earlier), marking any breaks on the main card and indicating any notes as necessary.
Correct the pre-printed depth indications as necessary, on the main core card and on all tear-offs. If an end of the core piece is not a straight break, then do not change the pre-printed depth listed on the tear-offs, this will be done on the CPL.
Add two additional "up arrows" for each piece of core. There should now be a total of 4 arrows at roughly 90° intervals.
At this time, anyone who would like to look at the entire drill run of core in one place may do so. Core Handlers should coordinate this as required.
- If there are core breaks in a section of core, they should be given maximum separation in order to allow the evaporation of nBA. Further wiping of the core break surfaces may also be appropriate to remove as much nBA as possible. The nBA was found to evaporate quickly from an exposed surface, but would remain in a closed break for many days, perhaps weeks. Separating the core breaks in the freezer allows as much nBA as possible to evaporate from the surfaces of the breaks.
It is possible that spacer blocks will be necessary to prevent the core from sliding in the core trays. If these are used, they should be placed at this time.
- Once the core cards have been updated, the two meter sections should be placed in the freezer. Fill out the Feeder Trench/Freezer In Data Sheet, including the date, time, the range of tube numbers for this run, and feeder trench and freezer temperature.
- The 11 cm sample from the physical properties group will be returned to the core trays before the core section goes to the CPL. While replacing these will be the responsibility of the physical properties personnel, the Core Handlers should provide assistance finding core sections, etc.
- As the freezer gets new core, core that has been in the freezer the longest should be moved to the Relaxation Trench. Fill out the Relaxation Trench In Data Sheet (date, time, tube number, relaxation trench temperature). Core will stay in the relaxation trench for as much as a several weeks, depending on rate of drilling, rate of core processing, and brittleness of ice.
Preparation of the core for the CPL is a critical task. The core must be reoriented (relative to itself) as close as possible to its original orientation in the ice sheet. This is accomplished using the core breaks. To date, the mating of core break faces has provided an effective means for reorienting any core pieces.
The physical properties sample cannot be oriented by matching faces since its end is cut square. Thus the orientation marks made in the drill dome must be used to reorient this piece. The physical properties sample should be oriented (along with the rest of the core) as indicated in the Sample Types report, i.e. so that the portions of ice removed from the sides of the sample are on top and bottom. This will allow minimal interference with the continuous analyses.
The core must also be lined up with the meter sticks on the CPL trays (aluminum, with lexan bases). This registration must be done very carefully as the depths of features observed in a section of core will be assigned a depth based on the depths indicated on the meter sticks.
The 2 meter sections of core, as prepared for the CPL core rays, that have top or bottom ends that are diagonal breaks need special attention. The record keeping convention adopted by Core Handlers in 1991 was "top long, bottom short". That is, use the measurement at the longest point of the core for the top or shallower end of core, and the shorter (less deep) measurement at the bottom or deeper end of the core. As the Core Handler goes from meter to meter logging the core for lengths and breaks, this convention, when used by all Core Handlers, will keep depths from seemingly being repeated from core card to core card.
The potential for repeats or gaps in continuous samples is possible if the orientation of diagonal breaks at the tops and bottoms of the 2 meter core sections is not considered. If the bottom of a piece of core is a diagonal break, then the next core tray must be brought out of the relaxation trench and oriented the same way, before the first piece can be sent onto the CPL.
The probes for taking the core wall temperatures should be placed on the side of the core between the core and the neoprene pads on the CPL trays in the process of preparing the core sections for the CPL.
Preparing Brittle Core in Storage for the CPL
- The Core Handlers should prepare core for the CPL as it is required. If temperatures in the feeder trench are below -15° C (which should be most of the time), a few sections of core may be prepared in advance. If the temperature is too high, then only one section should be prepared at a time, and only at the last minute before it is required in the CPL.
- The Core Handlers should get information about the timing of core preparation from the Horizontal Saw Operator, and the CPL Manager and send prepared core to the CPL as he/she indicates.
Some core collected in 1991 was too fragile for cutting into 2 meter sections. This core will need to be cut before it is sent to the CPL. A new cross cut saw will be assembled in the relaxation trench to accomplish this task. The procedure is similar to the procedure used when the core is extruded from the barrel in the drill dome.
The following procedures should be followed for the brittle core in storage (720 to 1372 meters).
- Place an empty drill tray on the left of the saw (if the core is going directly to the CPL then use a core tray).
- Select a section of core from the storage rack and place it to the right of the saw.
- Move the necessary pieces of core to the empty drill tray so the core can be cut on an even 2 meter mark. Consult the core cards to make sure the core is properly lined up and oriented at any breaks.
- Use the saw to cut the core at the 2 meter mark.
- Fill out new core cards with the correct Tube Numbers, new top and bottom depths, new quality ratings, and new break location measurements. In the box provided on the core cards, be sure to record previous Tube Numbers associated with each section of core. Place new core card in tray with core. Place old core card in folder provided by the Data Manager.
- Place drill tray with newly assigned two meter section back on core storage rack in its correct position.
- Select next drill tray from storage rack and place it to the right of the saw.
- Proceed from step #3 above.
In the brittle ice zone there was some core loss resulting in depth uncertainties. These core loss events are noted on the core cards. Core Handlers will be provided guidance for labeling core sections as accurately as possible.
The horizontal saw, clear table, and wing slabbing stations are closely interconnected. Two people should be able to run all three stations with one person primarily on the horizontal saw, another primarily at the wing slabbing station, and the clear table being shared by both. The exact arrangement should be worked out on site.
The Horizontal Saw Operator should indicate to the Core Handlers when he/she will need another section of core early enough so that they can get the core from the relaxation trench and prepare it for the CPL.
The temperature of the CPL is a major concern. With the motors, lights, ventilation, and people in the CPL, it is possible that the temperatures will go above -15° C. If it goes too high, the Chief Scientist will shut down CPL operation until cooler temperatures can be attained. Only the core section that is being processed should be in the CPL at any time.
Principle tasks of the horizontal saw operator are:
- When ready for the next section of core, get the prepared core section from the Core Handlers. Fill out the CPL In Data Sheet: Date, Time, Tube Number, CPL Temperature, and Core Wall Temperature.
- Cut the two slabs on the core and send the section on to the Clear Table.
- Clear Table duties as determined.
The Clear Table position is shared by the Horizontal Saw Operator and the Wing Slabber. The tasks are written up here as though as single person carried them out, even though they are shared. There is risk of dropping sections of core at the clear table and extra care must be used.
The main tasks of the Clear Table person are:
- Take the core, with the two cut slabs on top, from the Horizontal Saw Operator and move the top slab onto the table, leaving the main core in place for reference. Gently brush any ice dust away from the slab.
- Using the main core, the breaks indicated on the core card, and Clear Table ruler as reference, arrange the slab as it would have been in the ice sheet. Having done this, the 1.000 meter mark should fall directly under the band saw. If not, check your arrangement. Make the 1.000 meter cut. The accuracy for this cut should be at least 0.25 cm. If there is a break in the slab within 2 cm of the 1.000 meter mark, do not make the cut, but adjust the pre-printed depths on the tear-offs instead.
It is critical that the 1-meter cut is accurately made since it must match the 1-meter cut made on the main core archive at the Packing Table.
- Update the tear-off(s) for the slab, and mark the tops (as with the main core) of any pieces that do not have top marks on them.
- Put the slab into its box, along with its tear off, and set it in the waiting shelves for its next station. The SG 1 slab (ISO01/ALL01 samples), goes into waiting shelves for the packaging table. The SG 2-5 slab goes to the wing slabbing waiting shelves.
- Repeat 1 - 4 for the second slab. It is possible that both slabs will be cut a one time.
- Brush any ice dust from the main core and send it to the ECM station.
The SG 2 -5 slab is further cut at the wing slabbing station. The Wing Slabber gets this piece, along with its tear-offs from the waiting shelves where it has been placed by the Clear Table person.
The major task of the Wing Slabbing station is to Cut the slab into the four sample sections. As each section is cut, it should be lined up with the wing slabbing ruler, and the specific tear-off for that piece updated. Put the tear-off into the box with the piece and place the box in the appropriate waiting shelf.
The ECM station takes the main core (still two meters long) and core cards from the clear table after both horizontal slabs have been removed. During the ECM measurement, the temperature of the core is taken from holes drilled in the core (TAY05) and the core wall temperature as measured by the probes mounted by the Core Handlers. These values should be recorded on the data sheet provided by the Data Manager along with the date, time, and tube number. Once the ECM is completed, it is passed on to the stratigraphy station.
The stratigraphy station personnel take the core and core cards from the ECM station, perform their analysis, and pass the core onto the packing table. After the core has been cut at the packing station, the stratigraphy station personnel should look at the core again and mark its quality on the “packing quality” section of the core cards and make any final notes before the core is packed in the tube.
Once the core has been through the ECM and the Stratigraphy station, it is cut to 1 meter length, and packed in core tubes for shipment to the US.
It is critical that the 1-meter cut is accurately made since it must match the 1-meter cut made on the slabs at the Clear Table.
All the bags and tubes to used on any given day should be pre-labeled, using magic marker (we have been unable to find stick-on labels that will stick on cold polyethylene...), before the CPL day begins to insure legibility and reduce the amount of thinking that must be done with cold hands and feet.
Example of labeling to be placed on core tube top and core tube.This same labeling should be used on the polyethylene liners.Arrows point up!
Specific tasks of the Packaging Table position are:
- Cut the 2-meter long piece at the 1.000 meter mark. Accuracy of at least 0.5 cm should be maintained. If there is a break within 2 cm of the 1.000 meter mark, the cut should not be made and the core card depth should be updated to reflect the actual depth. After the cut (before loosening the core from the tray), a physical properties person should inspect the core, and update the core card to reflect the current state of the core (main core archive) and grade the quality of the core (Packaging Table Quality on core card).
- When the 2-meter section has been cut, but before it has been released from the CPL tray, read the core wall temperature, and fill out the Packing Table Data Sheet. This includes the Date, Time, Tube Number, and Core Wall Temperature.
- Bag the core and put in core tube. The SG 1 (ISO01/ALL01) slab (see below) also goes in the core tube with the main core archive (MCA), if it has not been sampled. Both the MCA and the SG 1 slab should go into liner that has been labeled (see above) with "GISP2 D", the tube number, and depth range. The tube should then be placed in the storage trench waiting rack. Fill out the Storage Trench In Data Sheet with the date, time, tube numbers, and storage trench temperature
- The core card and SG 1 tear-off should be set aside to be taken to the science hut to be photocopied The core card copies should then be returned to the correct core tubes and the original tear-offs for the SG 1 slabs should be stapled to the SG 1 liners. Once the core card copies and the original tear-offs have been returned to the core tubes, the tubes should be put in ISC boxes. When each ISC box is full, it should be labeled with; GISP2 Core D, and the tube numbers XXXX - XXXX (e.g., 907 - 910).
- The ARC01 pieces should be collected from the waiting shelves where the Wing Slabber has left it. After updating the tear-offs with all break information, these pieces should be put into their pre-labeled liners (GISP2 Core D, ARC01, tube number, and depth range) and the tear-offs set aside for the Data Manager. The bagged ARC01 pieces should be set on the waiting shelves in the storage trench until the Data Manager returns the tear-offs. When the original ARC01 tear-offs are returned, they should be stapled to the correct liner, and the ARC01 pieces should then be put in ISC boxes. These pieces should be arranged in layers, with each layer separated by bubble wrap. Again, when the ISC box is full, the box should be labeled with; GISP2 Core D, ARC01, and the depth range.