memo: review of ges well completion data

SFUND RECORDS CTR

2073238

IT CORPORATIONA Member of The ITCrvap

1T/EMCON

1326 N. Market Boulevard PHONE: 916/928-3300Sacramento, California 95834-1912 FAX: 916/928-3341

MEMORANDUM

TO: Sunrise Mountain Landfill Team DATE: December 27,2001PROJECT: 822180/05010000

cc: U.S. EPA, Steve WallMr. Alan Gaddy - RSSNMs. Susanna Trujillo - USEPAMr. John Schlegel - Clark CountyMr. Mark Morse - BLMMs. Sandy Doty - SAICMr. Steve Smith - SCSMr. Derek Reves - SCS (Sunrise)

FROM: Martin Miele R.GP, R.GDan Easter

RE: Review of GES' Well Completion Data

Monitoring Well Location 1

A total of two wells (MW-1A, PW-1C) were installed by GES at Location 1. The wells arewithin fractured bedrock of the Frenchman Mountain fault zone. Only one of the wells (PW-1C)encountered water. The water level in PW-1C appears to have stabilized at approximately 246feet bgs (elevation 1763).

GH-1A\MW-1A

GH-1A was logged to a depth of 100 feet with gamma, resistivity and conductivity probes. Thisis above the water table as all samples were reported to be dry. The significant increase in gammaresponse, decrease in resistivity, and increase in conductivity at a depth of approximately 75 feetbgs indicate that there is likely a significant increase in clay content below 75 feet bgs. This

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distinction is not resolved in the lithologic logs as clay is the predominant feature in the boringlogs both above and below the 75 feet depth.

Above 75 feet bgs the data from the three logging tools correlate well with each other. Relativeincrease in gamma response, decrease in resistivity, and increase in conductivity occurs at 20 feetbgs, 30 feet bgs, 40 feet bgs, and 55 feet bgs indicate local increases in clay content. However,the local increases are of less magnitude than below 75 feet bgs, therefore, the clay content is lessabove 75 feet. The zones between 20, 30,40, and 55 feet bgs are dominated by sandier materials.There is very little correlation between the geophysical and lithologic logs in this hole. Theirregular data at approximately 5 feet bgs and 25 feet bgs is not understood but may be due toburied metal or another unknown interference.

GH-1ANMW-1A Well ScreenThe screened interval is reported to be at 85 to 95 feet bgs (95 feet bottom of hole). Although nowater was encountered, a tuffbed occurs from 82 to 88 feet bgs. The tuff can be permeable ifwater is present. A ten foot screen interval from 80 to 90 feet would have covered the entire zoneoccupied by the tuff and may have been more optimal. However, the lack of water in the shallowzone makes the interval less important.

GH-1C/PW-1CGH-1C was logged to a depth of 680 feet with gamma, and neutron probes. It is described as dryto slightly moist in the boring logs. The gamma ray probe indicates a lot of variation from zero toapproximately 260 feet bgs. This due to several thin layers (5 to 10 feet thick) of clay interbeddedwith limestone, dolomite and siltstone. The boring logs indicate several interbedded sequences,however, many of the sequences are not resolved in the boring log that are indicated in the gammadata. The gamma data indicate a significant decrease and become more uniform from 260 feetbgs to 400 feet bgs. Limestone is logged in the boring log data at those depths. This suggeststhat the limestone is generally consistent in properties and may be massive limestone.

From 400 to 680 feet bgs the gamma ray data show a general increase with several thin zones ofmarked gamma increase superimposed. This suggests a general increase in clay content withseveral thin clay layers or fractures filled with clay. One major increase in gamma values occursfrom 430 feet bgs to 450 feet bgs that correlates with siltstone hi the boring logs. However,limestone is logged from 400 feet to 680 feet bgs (except for the siltstone at 430 to 450 feet bgs).Therefore, the lithologic logs did not resolve the several thin clay layers or fractures indicated hithe gamma ray data. These occur at approximately 410, 470, 500, 530, 580, 620 and 650 to 680feet bgs.

The neutron data indicate three major zones. From zero to approximately 300 feet bgs neutrondata indicate a general increase in values, which indicate that subsurface materials may be gettingdryer. Some water may be present in the interbedded sequence resolved by the gamma ray data.

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From 300 feet bgs to 480 feet bgs neutron values are very high. This zone correlates withlimestone suggesting that the limestone is generally massive and unfractured (probably dry).Below 480 feet bgs neutron data indicate a decrease and generally decrease to the bottom of thehole. This typically indicates an increase in moisture. Limestone is logged in that section of theboring logs, however, the limestone may be fractured forming a fracture aquifer. The water tablemay be at approximately 480 feet bgs. The shallow low neutron values (zero to 300 feet bgs)may be due to water perched upon a massive limestone (from 300 to 480 feet bgs). Sandstonewas logged from 660 to the bottom of the hole. An increase in gamma values occurs at thosedepths suggesting that the sandstone may be fractured with clay lining.

GH-1C/PW-1C Well Screen

Two saturated zones are reported between 666 feet and 672 feet bgs. The screened interval isreported to be from 657 to 682 feet bgs which encompasses both saturated zones. Water levelranges from 246 to 622 feet bgs from October 2000. Sandstone (overlain by limestone) occurswithin that depth interval. We agree with the screened interval due to the decrease hi neutronvalues, and the possibility of water occurring within the likely fractured sandstone as well as alongthe limestone/sandstone interface. Water was detected in the boring logs along that interface.


A total of seven wells (MW-2A [2-inch], MW-2A [4-inch], PW-2B, PW-2C2 [2-inch], PW-2C2[4-inch], PW-2D, and PW-2D2) were installed by GES at Location 2. Water level records forthese wells were reviewed and potential effects on water levels from groundwater sampling eventswere considered.

Water levels appear to have stabilized in wells MW-2A [2-inch], PW-2B, PW-2C2 [2-inch], andPW-2C2 [4-inch] at elevations ranging from about 1688 to 1700 feet. Well screens for thesewells range from 200 feet to 263 feet bgs. Based on water levels and well screen depths, itappears that these wells may be screened in the same water bearing zone. Aquifer testing and/orwater quality evaluation is needed to confirm this observation. Well MW-2A (4-inch) is dry.

The water levels in wells PW-2D, and PW-2D2 fluctuate considerably. Water elevations in wellPW-2D range from about 1445 feet to 1710 feet, and in well PW-2D2 range from 1690 feet to1745 feet. The well screen interval for well PW-2d is about 85 feet below well PW-2D2. Basedon water level and well screen data, it is evident that these two wells are not screened in the samewater bearing zone as wells MW-2A [2-inch], PW-2B, PW-2C2 [2-inch], and PW-2C2 [4-inch],The data do not indicate whether wells PW-2D and PW-2D2 are screened in the same waterbearing zone.

GH-2A/MW-2A (2-inch and 4-inch wells)

GH-2A was logged to a depth of 200 feet with gamma, resistivity and conductivity probes. It isdescribed as dry to slightly moist in the boring logs. The gamma ray data indicate a slight increase

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in values at approximately 60 feet bgs and is likely due to a slight increase in clay content. Otherthan the slight increase, the gamma ray data is generally featureless. Most of the materials below60 feet bgs are logged as clay and clayey sand hi the boring logs with the exception of silty gravelfrom 150 feet bgs to 190 feet bgs.

The resistivity and conductivity data indicate several high resistivity zones from 130 to 190 feetbgs. Several zones occur at 130,137,150,160 168,175, and 181 feet bgs. Gravels and sandsare logged hi the boring log data at those depths. These would have been favorable for screening.

GH-2A\MW-2A Well Screen

The screened interval for the 2-inch well is located from 205 feet to 215 feet bgs. The saturatedzone is shown to be 208 to 215 feet bgs. Water levels are reported between 196 feet and 200 feetbgs. However, the moisture content column does not indicate saturation. If it is saturated, thescreened interval is appropriate. This corresponds with the onset of clayey sand. No geophysicaldata exists at that depth.

The screened interval for the 4-inch well is 180 to 195 feet bgs. The well initially (May/June2000) had water at a depth of about 195 feet bgs or 1693 elevation. The well has been dry sinceSeptember 2000.

GH-2B\PW-2B

GH-2B was logged to a depth of 200 feet with gamma, resistivity and conductivity probes. It isdescribed as dry to moist in the boring logs.

The gamma ray data indicate a marked increase in gamma ray values and the resistivity probesindicate a marked decrease (conductivity probe increase) from approximately 50 to 60 feet bgs.This is due to the presence of clayey sand that was logged in the boring log at that interval. Thegamma ray and conductivity data indicate slight increases at 80, 105, and 175 feet bgs. Theresistivity data indicate decreases at those intervals. These correspond to clayey gravel and clayeysand at those intervals on the boring log.

Significant increases in resistivity occur at approximately 130, 150, and 180 feet bgs. These zonesare generally 10 to 15 feet thick and are also associated with a decrease in gamma ray andconductivity data. These are logged as silty sand and gravel in the boring logs.

GH-2B\PW-2B Well Screen

The screened interval occurs from 200 to 215 feet bgs. A saturated zone is reported from 205feet to 215 feet bgs. The saturated zone correlates with the moisture content data and, therefore,the screened interval is appropriate. Water level has either been dry or approximately 202 feetbgs.

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GH-2CXAB-2C, PW-2C2 (2- and 4-inch diameter wells)GH-2C was logged to a depth of 225 feet with gamma, resistivity and conductivity probes. It isdescribed as dry to moist in the boring logs to 215 feet bgs and saturated from 215 to 246 feet bgs(bottom of hole). The gamma ray data indicate an increase in gamma ray values and the resistivityprobes indicate a decrease (conductivity probe increase) from approximately zero to 30, and from160 to 185 feet bgs. These are likely due to an increase in clay content at those intervals.However, there is no indication in the boring logs. Most of the borehole is logged as clayey sandto silty sand which is difficult to discern while logging. The logs are also somewhat featurelessdue to the small contrast hi physical properties for most of the borehole.

PW-2C2Well Screens

No well was installed at GH-2C. However, wells PW-2C2 (2 and 4 inch diameter wells) wereinstalled close to AB-2C and have very similar lithology (close to identical). The well screenswere installed from 242 to 247 feet bgs in the 2 inch well and 258 to 263 hi the 4 inch well. Thewater depth in these wells is approximately 218 to 222 feet bgs. These are both within thesaturated zone and deemed appropriate for depth.

GH-2D\PW-2D, PW-2D2

GH-2D was logged from 250 feet to a depth of 800 feet with gamma, and neutron probes. Thegamma ray probe indicates a marked increase from 390 to 430 feet bgs and the neutron probeindicates a decrease in the same depth range. This indicates wet clay. A high plasticity claycorresponds to that depth interval in the boring log.

Gamma ray values above 390 feet bgs are lower than the remainder of the borehole. Thisindicates sandier materials. In the borehole log, materials above 390 feet are logged as generallysandy materials. Gamma ray values below 430 feet are higher than the values above 390 feet bgs.This indicates an overall increase to clay content. Silty clay is generally logged below 430 feet tothe boring log. Two slight decreases to gamma ray response occur at 470 feet bgs and 520 feetbgs. These are thin localized features that likely indicate sandy zones. The shallower one (470feet bgs) is logged as a sandstone and the deeper one (520 feet bgs) is not resolved in the boringlog data. Several slight increases to gamma ray data occur below 550 feet bgs. They are probablythto clay zones. However, they are not resolved to the borehole data.

Neutron log data are low at the beginning of the logged interval (250 feet). These correspondwith a zone logged as gravel and sand. The gravel and sand are likely wet to saturated and mayrepresent a perched water zone. From the base of that zone (270 feet bgs) to 390 feet bgs (top ofhigh plasticity clay), neutron data indicate an increase which suggests a decrease to water content.This also supports the perched water zone interpretation. Neutron values below 430 feet aregenerally lower than those above 390 feet bgs. This suggests an increase in water content andmay represent saturated conditions.

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GH-2DYPW-2D, PW-2D2 Well Screen

Well PW-2D is screened from 508 feet to 533 feet bgs. This is reported to be a saturated zone,however, several saturated zones occur to the data. This zone corresponds to a decrease togamma values indicating a sand stringer (although it is not shown on the lithologic log). A similarhigher magnitude response occurs at the bottom of the hole at 800 feet depth. The geophysicalresponse indicates that the sandy zone may be thicker at that depth.

Well PW-2D2 is screened from 425 to 440 feet bgs. This corresponds with the onset of lowneutron values likely indicating the potentiometric surface. Water levels ranged from 173 feet bgsto 431 feet bgs. The interval also coincides with the interface between a wet, high plasticity clayover a silty clay. The interface at that depth is likely a good producer and will give water data tothe shallow zone. This is considered a favorable zone for screening.

Monitoring Well Location 4A total of three wells (PW-4A, PW-4B, and PW-4C) were installed by GES at Location 4. Thewater level to well PW-4A (well screened 185 to 205 feet bgs) has remained relatively stable sincethe first groundwater sampling event to June 2000. The water level appears to have stabilized atabout 185 feet bgs (elevation 1679).

Water level records for wells GH-4B and GH-4C show increasing water levels following agroundwater sampling event to January and March 2001, respectively. The GH-4B (wellscreened 775 to 800 feet bgs) water level went from a low of 675 feet bgs (1189 elevation) to itshighest at about 162 feet bgs (elevation 1703) to August and September 2001, prior to an October2001 sampling event. The water level to well GH-4C went from a low of 442 feet bgs (1423elevation) to a high of 165 feet bgs (1699 elevation) prior to the October 2001 sampling event.

GH-4A

GH-4A was logged to a depth of 300 feet with gamma ray, resistivity, conductivity, and neutronprobes. In general the gamma ray data indicate low values from the surface to a depth ofapproximately 60 feet bgs. These are logged as clayey sand and silty sand on the boring log.Gamma ray data indicate a marked increase from 60 feet to approximately 220 feet bgs. Thisindicates a general increase in clay content. The lower part (150 feet to 220 feet bgs) ischaracterized by variations to gamma data that resemble interbedded units. High plasticity clayand elastic silt are logged within that interval and are toterbedded with few gypsum and gravelunits between 165 and 195. Gamma ray day indicate a significant drop (in values) atapproximately the 220 feet depth. This suggests a decrease to clay content. However, the boringlogs indicate high plasticity clay to that interval also. There is likely a change to the physicalnature of the clay that is not evident to the boring logs. Clay mineralization may have changed orthe clay may actually be silt.

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Resistivity and conductivity data were obtained from 170 feet to 300 feet bgs. The data indicateslight fluctuations, as do the gamma ray data below 170 feet bgs. The fluctuations suggesttoterbedded materials. However the boring log indicates all high plasticity clay.

GH-4A Well Screen

A saturated zone is reported from 180 to 210 bgs and the well is screened from 185 feet to 205feet bgs. Moisture content to that interval is logged from dry to slightly moist. This interval islogged to have high plasticity clay in the lower zone and a thin gravel zone to the upper part;however, a good section of the interval had no recovery. The zone occurs within the intervalcharacterized by large variations to gamma data that are typical of toterbedded units. Thegeophysics data and lack of recovery suggest gravelly permeable deposits and the screen zone isappropriate.

GH-4B/GH-4C

GH-4B was logged to a depth of 810 feet with gamma ray and neutron probes, and to a depth of200 feet with resistivity and conductivity probes. The boring logs indicate that from surface to adepth of approximately 575 the materials are primarily clay. From 575 feet bgs to the bottom ofthe hole is dominated by silty sand.

In general the gamma ray data indicate low values from the surface to a depth of approximately440 feet bgs. This zone is dominated by primarily high plasticity clay. The gamma ray dataindicates an increase from 440 feet bgs to 575 feet bgs. This zone is dominated by primarily lowplasticity clay. The gamma ray values indicate another increase from 575 feet bgs to 800 feet bgs.This zone is dominated by silty and clayey sand. The lithologic logs are indicating the exactopposite trend from what to expect from the geophysical probes, and may be due to the specificcomposition of the clay materials.

The neutron logs indicate relatively low values from the surface to 600 feet bgs. This likelycorresponds to the high porosity to clay materials. The values increase from 600 to 800 feet bgswhich is dominated by sand. This is consistent with typical neutron probe responses.

Resistivity and conductivity data were obtained from surface to 200 feet bgs. The data indicate alarge increase in conductivity and decrease to resistivity that corresponds to a plastic clay loggedfrom 50 to 125 feet bgs. The resistivity and conductivity data agree well and are caused by theplastic clay. However, the same response is not observed to the plastic clays logged beneath 125feet (140 to 200 feet bgs). This may be due to a change to clay composition.

GH-4B/GH-4C Well Screen

A saturated zone to well GH-4B is reported from 778 feet to 803 feet bgs and the well is screenedfrom 775 feet to 800 feet bgs. Water levels ranged from 200 feet bgs to 675 feet bgs since June2000. Therefore screening the well at the lowest sand interval is favorable. The gamma data

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Therefore the screened zone is optimal.

The GH-4C well summary sheet indicates that a saturated zone exists from 458 feet to 465 feet.The well is screened from 455 feet to 470 feet bgs. Water levels ranged from 218 feet bgs to 462feet bgs since March 2001.


A total of two wells (PW-5B4 and PW-5C) were installed by GES at Location 5. The water levelto well PW-5B4 (well screened 600 to 625 feet bgs) appears to have stabilized at approximately177 feet bgs (1725 elevation). Well PW-5C (well screened 139 to 154 feet bgs) water level hasremained relatively stable since the boring was drilled. The water level is approximately 146 feetbgs (1753 elevation). Based on the water level data and the well screen intervals, it appears thatthese wells are not screened to the same water bearing zone.

GH-5B4\PW-5B4

GH-5B4 was logged to a depth of 710 feet with gamma ray and neutron probes. The boring logsindicate that from the surface to a depth of approximately 150 feet the materials are primarily sandand silt. From 150 to 500 feet, the materials are dominated by high plasticity clay and clayeysand. Silty sand and sandstone occur below 500 feet.

In general the gamma ray data indicate an increase with depth, with a marked increase atapproximately 400 feet bgs. The increase at 400 feet coincides with an interface where highplasticity clay overlies primarily clayey sand, silty sand, sandstone, and some gravel stringers.This is opposite of what is expected. Neutron data are generally high (greater than 1500 cps)from the surface down to 310 feet bgs. A marked decrease occurs at 310 feet bgs where neutronvalues decrease from approximately 1500 cps to less than 1000 cps. This is typical of saturatedconditions and may represent the water level during the geophysical survey. Neutron valuesindicate a gradual increase from 310 feet to the bottom of the hole. This suggests that the watercontent decreases.

GH-5B4\PW-5B4 Well Screen

A saturated zone is reported on the lithologic log from 605 feet to 622 feet bgs and the well isscreened from 600 feet to 625 feet bgs. Water levels range from 180 feet bgs to 500 feet bgssince September 2000. The well is screened to what is described as sandstone. It may befractured. However, several gravel stringers and clayey sands occur at approximately 550 feetbgs. This may have been a more favorable zone for screening.

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show three zones or lavers that are relative sandv and gravelly zones to the screen interval.

GH-5C

GH-5C was logged to a depth of 155 feet with gamma ray, resistivity, and conductivity probes.The boring logs indicate that from the surface to a depth of approximately 135 feet the materialsare primarily silty sands. Materials from 135 to 200 feet are dominated by clayey sand. In generalthe gamma ray data indicate flat values (average 50 cpi) from the surface to 20 feet bgs, and from60 feet bgs to a depth of 150 feet bgs. From 20 to 60 feet the gamma ray data increasesignificantly (80 to 100 cpi) to three distinct zones (30 feet bgs, 40 feet bgs, and 50 feet bgs). Theresistivity data decrease significantly to that zone. This indicates the presence of clay zones,however, the clay was not resolved to the boring log data.

Resistivity and conductivity data indicate a significant increase to resistivity and decrease inconductivity at 25 feet bgs and 70 feet bgs. The zones are likely 5 to 10 feet thick and are likelycaused by gravel zones that are not resolved to the boring log data. Lower magnitude increases toresistivity also occur at 80, 88, and 115 feet bgs that were also not resolved to the data that arelikely caused by thin beds of gravel.

GH-5C Well Screen

A saturated zone is reported from 146 feet to 154 feet bgs and the well is screened from 139 feetto 154 feet bgs. Water levels ranged from 145 feet bgs to 147 feet bgs since June 2000.Therefore screening the well at the lowest section is favorable. The gamma data show a zone ofclayey sand to the screen interval. Therefore the screened zone is optimal.


A total of two wells (PW-6B and PW-6C) were installed by GES at Location 6. The water levelin both wells has remained relatively stable since the January 2001 groundwater sampling event.The water level to well PW-6B (well screened 201 to 226 feet bgs) and well PW-6C (wellscreened 406 to 431 feet bgs) is about 208 feet bgs (1763 elevation). Based on the water leveland well screen data, it appears that these two wells are installed in the same water bearing zone.

GH-6B

GH-6B was logged to a depth of 225 feet with gamma ray, resistivity, conductivity, and neutronprobes. The boring logs indicate that the materials are primarily sands and gravels.

In general the gamma ray data are flat suggesting a uniform distribution of clay minerals. Theresistivity data indicate very resistive materials from 25 to 50 feet bgs. This may be caused by agravelly zone; however, it is not resolved to the boring log data. From 110 feet to 225 feet theresistivity data indicate a gradual decrease to resistivity. This is likely due to a decrease tomaterial grain size with depth. The neutron probe indicates a marked decrease at a depth of 210feet. This marks the water table as logged to the borehole data.

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GH-6B Well ScreenA saturated zone is reported from 211 feet to 226.5 feet bgs and the well is screened from 201.5feet to 226.5 feet bgs. Water levels ranged from 208 to 209 feet bgs since July 2000. Severalgravel zones occur from 210 feet bgs to 225 feet bgs. Therefore the screened zone is optimal.

GH-6OPW-6CNo geophysical data were available for well GH-6C. The boring logs indicate clayey sands andgravels to a depth of approximately 430 feet bgs. The gravels increase with depth and gravelsare the primary sediments below 200 feet bgs.

GH-6OPW-6C Well ScreenA saturated zone is reported from 330 feet to 431 feet bgs and the well is screened from 406 to431 feet bgs. Water levels ranged from 208 to 357 feet bgs since November 2000. Several graveland sandy zones occur below 406 feet bgs. Therefore the screened zone is optimal.

Monitoring Well Location 8A total of two wells (PW-8A and PW-8B) were installed by GES at Location 8. The water levelin well PW-8A (well screened 383 to 398 feet bgs) has remained relatively stable since the wellwas installed to March 2001. The water level appears to have stabilized at about 388 feet bgs(1764 elevation).

The water level to well PW-8B (well screened 477 to 492 feet bgs) has fluctuated between 469feet and 491 feet bgs (1682 to 1660 elevation) since it was installed to March 2001.

Based on the water level and well screen data, it appears that these two wells are not screened inthe same water bearing zone.

GH-8AVPW-8A

GH-8A was logged to a depth of 398 feet bgs. The boring logs indicate limestone, siltstone,mudstone, and sandstone. GH 8A was logged with a neutron probe. The neutron data indicatenumerous localized variations (2000 to 3200 cps) from zero to approximately 385 feet bgs wherea marked decrease occurs. The decrease is likely the water table during the survey. The localizedvariations may be related to wet fracture zones to the hard rock.

GH-8ANPW-8A Well ScreenA saturated zone is reported from 395 feet to 398 feet bgs and the well is screened from 383 feetto 398 feet bgs. Water depths are approximately 388 feet to 396 feet bgs since January 2001.The water level data and neutron data indicate that the screened zone is appropriate.

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GH-8BXPW-8B

GH-8B was logged to a depth of 492 feet bgs. The boring logs indicate limestone overlyingsiltstone at a depth of 100 feet bgs. The gamma ray data indicate several variations throughoutthe data. Some of the variations are trends over 50 to 100 feet and some are localized variationsin gamma values. Very few of these features are resolved to the boring log data. Several of themmay be caused by localized fracture zones. The neutron data are generally featureless except for amarked decrease to cps at a depth of 200 feet bgs. This may be caused by the water table duringthe survey.

GH-8BVPW-8B Well Screen

A saturated zone is reported from 490 feet to 492 feet bgs and the well is screened from 477 feetto 492 feet bgs. Water depths are approximately 429 feet to 487 feet bgs since March 2001. Thewater level data indicate that the screened zone is appropriate for the existing well.


A total of two wells (PW-9A and PW-9B) were installed by GES at Location 9. The water levelto both well PW-9A (well screened 510 to 535 feet bgs) and PW-9B (well screened 450 to 475feet bgs) has remained relatively stable since the wells were installed to February and May 2001,respectively.

GH-9A\PW-9A; PW-9B

GH-9A was logged to a depth of 572 feet with gamma ray, and neutron probes. The boring logsindicate limestone and dolomite for the entire hole. Due to the physical nature of the subsurfacematerials, the gamma data are very irregular. The gamma ray data (and neutron data) exhibitmany localized increases to cps. This is likely due to clay filled fractures to the limestonematerials. Most of these features are not resolved to the boring log data. Neutron data are allvery high (off scale) indicating dry conditions from zero to approximately 450 feet bgs. A markedaverage decrease occurs at 450 feet bgs which may represent the water table during the survey.

GH-9A\PW-9A; PW-9B Well Screen

Saturated zones are reported from 457 feet to 463 feet bgs, at 472 feet bgs, at 515 feet bgs, andfrom 528 feet to 529 feet bgs. Well PW-9A is screened from 510 feet to 535 feet bgs. Well PW-9B is screened from 450 feet to 475 feet bgs. Water depths to both wells are approximately 449feet bgs since installation. The screened zones appear to be appropriate.

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A total of one well (PW-10A) was installed by GES at Location 10. The water level to well PW-10A (well screened 705 to 720 feet bgs) has remained relatively stable since the well was installedto February 2001. The water level appears to have stabilized at about 668 feet bgs (1760elevation).

GH-10A\PW-10A

GH-10A was logged to a depth of 744 feet with gamma ray, and neutron probes. The boring logsindicate primarily limestone and dolomite for the entire hole. Due to the physical nature of thesubsurface materials, the gamma data are very irregular and are only marginally toterpretable. Thegamma ray data appear to exhibit an increase to values at approximately the 300 feet depth. Thismay indicate an increase to potassium to the limestone. Neutron data are all very high (off scale)indicating dry conditions. However, several zones of a drop to neutron data occur. These may befracture zones and may be saturated. No other information can be extracted from the data.

GH-10AVPW-10A Well Screen

A saturated zone is reported from 712 feet to 714 feet bgs and the well is screened from 705 feetto 720 feet bgs. Water depths are approximately 668 feet bgs since January 2000. The thinproducing zone to limestone suggests that a fracture zone was screened. It may not havesustainable yield however, it is a good zone for screening.


A total of three wells (PW-11 A, PW-1 IB, and PW-11C) were installed by GES at Location 11.The water level to well PW-11A (well screened 392 to 407 feet bgs) has fluctuated between 189and 197 feet bgs (1702 to 1694 elevation).

Water level to well PW-1 IB (well screened 245 to 260 feet bgs) has remained relatively stablesince the well was installed to November 2000. The water level appears to have stabilized atabout 193 feet bgs (1698 elevation).

PW-11C (well screened 803 to 828 feet bgs) water level has fluctuated between 345 and 738 feetbgs (1539 and 1147 elevation).

Based on the water level and well screen data, it appears that wells PW-11A and PW-1 IB may beinstalled to the same water bearing zone.

GH-11A\PW-11A

GH-11A was logged to a depth of 407 feet with gamma ray, conductivity, and neutron probes.The boring logs indicate that materials are silty sands to a depth of 225 feet bgs. Interbeddedgravels, silty sand, clay, gypsum, and caliche occur below 225 feet bgs to the bottom of the hole.

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In general the gamma ray data are generally featureless to a depth of approximately 225 feet bgs.Below 225 feet the gamma ray data indicate a gradual increase, with several localized variations,that correspond to the interbeds at depth. Conductivity data obtained from 250 feet bgs andbelow indicate a large increase from 285 feet bgs to 300 feet bgs which corresponds to a highplasticity clay. Neutron data indicate sharp decreases at 225 feet and 395 feet bgs. One may bedue to the water table during the survey.

GH-11A\PW-11A Well Screen

A saturated zone is reported from 402 feet to 407 feet bgs and the well is screened from 392 feetto 407 feet bgs. Water depths ranged from 190 feet bgs to 400 feet bgs since June 2000. Due tothe depth of water the screened interval is appropriate.

GH-11B\PW-11B

GH-1 IB was logged to a depth of 259 feet with gamma ray and neutron probes. The boring logsindicate that materials are generally silty sands and clayey sands. The gamma ray data start at 250feet bgs and end at 259 feet bgs. The reason for this short tool run is not apparent. The neutrondata are generally featureless throughout the boring.

GH-11B\PW-11B Well Screen

A saturated zone is reported from 246 feet to 259 feet bgs and the well is screened from 245 feetto 260 feet bgs. Water depths ranged from 192 feet bgs to 220 feet bgs since November 2000.Due to the depth of water and material types the screened interval is appropriate.

GH-11C

GH-11C was logged to a depth of 830 feet with gamma ray and neutron probes. The boring logsindicate that materials are generally clayey sand with some silty gravel. In general the gamma raydata indicate a significant increase at approximately 285 feet bgs. This is due to an increase toclay materials. A high plasticity clay is logged from approximately 290 to 310 feet bgs.However, gamma values remain relatively high to the bottom of the hole.

Neutron data indicate low values from the surface to 250 feet bgs and below 400 feet bgs.Neutron values are high between 250 and 400 feet bgs. This suggests a dry zone to that interval.The decrease in neutron cpi at 400 feet is typical of the water table occurring at that depth. Thelow values down to a depth of 250 feet may be due to a perched water zone that is separated fromthe water table. Most of the silty gravels are shallower than 250 feet which may support thepresence of a perched zone.

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GH-11C Well Screen

A saturated zone is reported from 818 feet to 827 feet bgs and the well is screened from 803 feetto 828 feet bgs. Water depths ranged from 240 feet bgs to 707 feet bgs since June 2001. Due tothe large variation in water depth the well should be screened deep. Clayey sands occur withinthe screened interval. The screened interval is appropriate.

Monitoring Wen Location 12

A total of three wells (PW-12A, PW-12B2, and PW-12D) were installed by GES at Location 12.The water level to well PW-12A (well screened 242 to 252 feet bgs) has remained relatively stablesince the well was installed to October 2000. The water level appears to have stabilized at about200 feet bgs (1680 elevation).

Water level to well PW-12B2 (well screened 469 to 484 feet bgs) fluctuated between 169 and 254feet bgs (1713 and 1628 elevation).

PW-12D (well screened 795 to 810 feet bgs) water level has fluctuated between 249 and 787 feetbgs (1629 and 1091 elevation).

Water bearing zone relationships can not be determined from the water level and well screen data.Aquifer testing and/or water quality evaluation should be completed to help resolve therelationships.

GH-12A\PW-12A

GH-12A was logged to a depth of 252 feet with gamma ray, resistivity and conductivity probes.The boring logs indicate toterbedded gravel, silty sand, well graded sand, and silty clay to a depthof approximately 145 feet bgs. From 145 feet bgs to 252 feet bgs the boring logs indicate lowplasticity clay.

In the upper section (zero to 140 feet bgs), the gamma ray data indicate several localizedvariations that correspond to the variety of clay content to the bedded materials. The gamma raydata indicate a very significant increase from 140 feet bgs to 175 feet bgs. The conductivity probedata also indicate a very large increase. This corresponds with the upper section of low plasticityclay. From 175 feet bgs to 252 feet bgs both the gamma ray data and conductivity data indicatesignificant drops with several localized increases and decreases superimposed on the geophysicaldata that are not resolved to the boring log data. The resistivity data correlate with theconductivity data except for opposite trends as expected. Low plasticity clay is also logged from175 to 252 feet bgs. The trends in the data indicate a change to the physical nature of the lowplasticity clay (indicated to the boring log). The composition of the clay is likely different to theupper section than the lower section. The lower section likely exhibits an increase of silt or sandcontent.

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GH-12AVPW-12A Well ScreenA saturated zone is reported from 246 feet to 252 feet bgs and the well is screened from 242 feetto 252 feet bgs. Water depths ranged from 198 feet bgs to 207 feet bgs since June 2000. Due tothe water depth and similar nature of the materials at depths below 140 feet bgs, the well shouldbe screened deep. Therefore the screened interval is appropriate.

GH-12B2VPW-12B2

GH-12B2 was logged to a depth of 484 feet with gamma ray, resistivity, conductivity, andneutron probes. The boring logs indicate toterbedded gravel, silty sand, well graded sand, siltyclay, and gypsum/rock salt. The interbedded units have a wide variety of thickness and vary fromless than 1-foot to 50 feet.

In the upper section (zero to 240 feet bgs), the gamma ray data show an average value ofapproximately 50 to 70 cps with several localized variations (increases and decreases) thatcorrespond to the toterbeds. Some of the localized variations are not resolved in the boring logdata. The conductivity and resistivity data were obtained from 240 feet bgs to the bottom of thehole. Below 240 feet the gamma log and conductivity data indicate extreme variations withlocalized increases and decreases. This is caused by the numerous zones of anhydrites (gypsumand salt) with toterbedded clay to the lower section. The gamma ray and conductivity responsefrom interbedded gypsum and clay is extreme due to the high conductivity of clay and extremelow conductivity of gypsum. Virtually every gypsum and clay layer is resolved in the conductivityand gamma ray data.

The neutron data from zero to approximately 350 feet bgs is flat for the most part except for alocalized decrease at approximately 230 feet bgs. A significant decrease occurs at 350 feet bgswhich is likely the water table during the field survey.

GH-12B2\PW-12B2 Well Screen

A saturated zone is reported from 474 feet to 483 feet bgs and the well is screened from 469 feetto 483 feet bgs. Water depths ranged from 179 feet bgs to 400 feet bgs since October 2000;however, most of the water levels are approximately 180 feet bgs. The screened interval does nothave lithologic data associated with it. The lowest unit to the well is logged as clayey sand. Ifthat unit continues at depth, the screened zone is appropriate.


A total of one well (PW-14A) was installed by GES at Location 14. The water level to weft PW-14A (well screened 211 to 226 feet bgs) has remained relatively stable since the well was installed

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to November 2000. The water level appears to have stabilized at about 216 feet bgs (1694elevation).

GH-14AXPW-14 A

No geophysical data were available for well GH-14A. The boring logs indicate silty and clayeysands to a depth of approximately 226 feet bgs. Three thin gravel zones occur from zero toapproximately 80 feet bgs.

GH-14A\PW-14A Well Screen

A saturated zone is reported from 219 feet to 226 feet bgs and the well is screened from 211 to226 feet bgs. Water levels ranged from 216 to 225 feet bgs since November 2000. Given thegroundwater depth, the screened zone is optimal. The well became dry to January of 2001.

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memo: review of ges well completion data

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