preliminary groundwater elevation contour maps

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Environmental Consultants

S C S E N G I N E E R S

2031491

PRELIMINARY GROUNDWATER ELEVATIONCONTOUR MAPS

FOR THESUNRISE MOUNTAIN LANDFILL

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PRELIMINARY GROUNDWATER ELEVATIONCONTOUR MAPS

FOR THESUNRISE MOUNTAIN LANDFILL

CLARK COUNTY, NEVADA

Preparedfor:

Republic Services of Southern Nevada770 East Sahara Avenue

Las Vegas, Nevada 89104(702) 644-4594

Prepared by:

SCS ENGINEERS2702 North 44th Street

Suite 105BPhoenix, Arizona 85008

(602) 840-2596

February 18, 2002File No. 10. 199007.01 Task 4

if

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CONTENTS

ISection Page

HISTORY 1

* GROUNDWATER MONITORING 1

I GROUNDWATER FLOW DETERMINATION 1

- CONCLUSIONS 3

- ATTACHMENTS

1 FIELD FORMS

I 2 TABLES

• 3 FIGURES

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PRELIMINARY GROUNDWATER ELEVATION CONTOUR MAPS

HISTORY

This report contains the initial attempt to establish Groundwater Elevation Contour Mapsfor the Sunrise Mountain Landfill. Maps presented within this report will change withadditional data from: aquifer testing to determine connectivity and continued water levelmeasurements, prior to becoming a Final Groundwater Contour Map. Therefore, thisrepresents the first and best attempt, using site knowledge and several water levelmeasuring events, to outline flow direction for this project with limited informationregarding hydraulic connection. Water level data and elevations for five sets of data wereinterpolated and contoured using Surfer 7 software. The resulting groundwater elevationcontour maps were used to evaluate groundwater flow direction and gradient within thethree water bearing units, identified through site data and knowledge, at varying depths atthe Sunrise Mountain Landfill.

GROUNDWATER MONITORING

The most recent bi-weekly groundwater-monitoring event was competed on February 6,2002 and utilized for the Preliminary Groundwater Contour Calculations. The overallgroundwater monitoring program includes boreholes GH-2E3, GH-3E, GH-7C, wellsMW-2A (2"), MW-2E, MW-2E2, MW-8B, MW-13D, MW-15B, MW-16A (2"),MW-16A (4"), and PW-1C, PW-2A (4"), PW-2B, PW-2C2 (2"), PW-2C2 (4"), PW-2D,PW-2D2, PW-4A, PW-4B, PW-4C, PW-5B4, PW-5C, PW-6B, PW-6C, PW-8A, PW-9A,PW-9B, PW-10A, PW-11A through PW-11C, PW-12A, PW-12B2, PW-12D, PW-13C,PW-14A, and TW-16B (Figures 1 through 3).

The depth to water was measured at each location and recorded on field forms with timeof measurement for the February 6, 2002 event. The field forms are provided inAttachment 1. The water level probe was decontaminated prior to use in each well usinga non-phosphate type detergent and water solution and rinsed using distilled water tominimize the potential for cross-contamination of the wells.

GROUNDWATER FLOW DETERMINATION

The northing and easting coordinates and elevations of all MW and PW wells weresurveyed, except as noted below, by a registered land surveyor to the nearest 0.01 foot.The ground surface elevations of boreholes GH-3E and GH-7C, and top of casingelevations of wells MW-13D, MW-15B, MW-16A (2"), and MW-16A (4") weresurveyed by field personnel to the nearest 0.01 foot. Water levels in the wells weremeasured to within 0.01 foot. The local groundwater flow direction was determinedusing water-level elevations from the boreholes and monitoring wells.

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Based on site knowledge, static water levels, screen intervals and boring logs, theboreholes and wells in the groundwater-monitoring program were divided into threecategories: First, Second, and Deep Groundwater. First Groundwater includes boreholesGH-3E and GH-7C, wells MW-2A (2"), MW-2E2, MW-15B, MW-16A (2"), MW-16A(4"), and PW-1C, PW-2A (4"), PW-2B, PW-2C2 (2"), PW-2C2 (4"), PW-4A, PW-5C,PW-6B, PW-8A, PW-9B, PW-10A, PW-11B, PW-12A, PW-13C, and PW-14A (Figure1). Second Groundwater includes borehole GH-2E3, and wells MW-8B, MW-13D, PW-2D, PW-2D2, PW-4C, PW-6C, PW-9A, PW-11A, PW-12B2, and TW-16B (Figure 2).Deep Groundwater includes wells MW-2E, PW-4B, PW-5B4, PW-11C, and PW-12D(Figure 3). The field personnel measured the water levels, one category at a time, inorder to minimize the barometric effects on the contour calculations.

The groundwater contour maps for the February 6, 2002 monitoring event correspond tothe above three categories and are presented in Figures 1, 2, and 3. Four additional datasets (October 5, 2001, July 6, 2001, December 6, 2001 and January 11, 2002), werecontoured to compare the results. The February 6, 2002 data was determined to have theleast amount of anomalous data due to interferences from pump tests, sampling events orwell development activities; and therefore was selected for the Preliminary ContourMaps. The groundwater contour map interpretations were generated from elevation datacontained in spreadsheet files (Tables 1 through 3). Tables 1 through 3 are provided inAttachment 2. The groundwater elevations were contoured using Linear Kriging gridmethod for Figure 1 and Radial Basis Functions grid method for Figure 3. Contour lineson Figures 1 and 3 represent lines of equal water table elevation in 5-foot intervals. Avariety of gridding methods were used to evaluate Second Groundwater, but no methodcould produce reasonable contours.

Several attempts to separate the Second Groundwater wells resulted in breaks in the dataand distortion of the contours. However, Figure 2 is presented with the location of theevaluated monitoring locations and corresponding water table elevation for reference.

The hydraulic gradient for the First Groundwater beneath the southern slope of the UpperDeck was essentially flat. The hydraulic gradient for the First Groundwater beneath theSouthern Flats was calculated between well PW-1C and MW-2E2. The groundwaterflow direction in this area was generally south with a hydraulic gradient of 0.0318.

The hydraulic gradient for the Deep Groundwater beneath the Southern Flats wascalculated using a three-point interpolation. Based on wells PW-5B4, MW-2E, and PW-4B, the groundwater flow direction was generally east with a calculated hydraulicgradient of 0.0884.

The above calculated gradients are preliminary, and will be verified when the aquifertesting program is complete to determine the interconnectivity of the zones. Thoseresults could change the calculated gradients depending on well groupings.

As an example of the effort required to complete the aquifer testing, a brief discussion ofthe Location 2 Aquifer Test is contained within this report. Initial aquifer testing was

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started at Well Location 2 in August of 2000. The initial aquifer testing attempts usingmedium flow pumps at Location 2, presented a number of challenges. The initial pumpsdid not provide any useable data because of the low recharge rate. Consequently, wellswere equipped with low flow pumps and pressure transducers. The initial results fromthese tests proved to be inconclusive, due to the effects of barometric pressure for staticconditions and cable stretch due to the extreme depth of the water zones. The staticvariations caused by barometric pressure proved to be very critical. These issues makethe aquifer testing requirements at the Sunrise Landfill extremely difficult and timeconsuming.

The revised and corrected aquifer testing at Location 2 started in November with 14 daysof static observations to determine baseline comparative data. The pump test started onDecember 11 and was shut down on December 24 (13 days) after 279 feet of drawdownwas induced using a low flow bladder pump (250 ml/hour). Because of the time frame, agenerator could not be relied upon. Clusters of bottled Nitrogen gas were utilized topower the pump. Well PW-2D was allowed to recover from the moment of pumpshutdown until 0716 January 9, 2002. Measurement of recovery was terminated at 54.2feet (approximately 80 percent recovered) of residual drawdown in order to begin thedata analysis process. The initial static test required 14 days, the pump test another 29days, and several additional days for transducer drift tests. This test produced over41,000 data points. The total pump test time and data evaluation required approximately45 days.

The current approved schedule indicates that the Aquifer Testing Report is due to EPA onJune 14, 2001. Based on the results from the aquifer testing at Location 2, the currentschedule for the Aquifer Testing Submittal needs to be revised. Republic will assess theschedule and submit a revised schedule. The aquifer testing results and evaluation is acritical data element in completing the other associated Work Plan requirements.

CONCLUSIONS

In completing the aquifer testing program outlined above, the results of the groundwater' contouring analysis can be verified. With this in mind, preliminary data shows thesoutherly groundwater flow direction of the First Groundwater under the southern slopeof the Upper Deck was very similar to the southerly direction of groundwater flow underthe Southern Flats.

There was a noticeable change in the calculated groundwater gradient between thesouthern slope of the Upper Deck and the Southern Flats. The southern slope of theUpper Deck was relatively flat, whereas, the gradient under the Southern Flats was muchsteeper. The preliminary calculations indicate that the flow direction for the FirstGroundwater is approximately ninety degrees different from the flow direction of theDeep Groundwater. This is consistent with the contour calculations for the four previousmonitoring events conducted at the site.

SCS ENGINEERS

ATTACHMENT 1FIELD FORMS

1of2

Sunrise Landfill Water Level ReadingsBoring/Well ID

PW10A

PW9B

PW8A

PW1C

MW1A

PW14A

MW 2A - 2"

PW2A-4"

PW2B

PW 2C2 - 2"

W2C2-4"

W 2E2 - 2"

W1TB

H3E

3-6 ~

Date Time of Reading

£903

Depth to WaS'

9^3/9.

Total Depth

720

535

47

398

49

68

95

226

215

195

215

247

263

533

440

687

330

476

407

260

828

Name of Measurer

JL Ssi/s

. AaJ&&<;4

- Sfc>J'

&Ze?&

/&

^L_

*3 Sl0jf£tee?tt

^j.S)A rAties'6

31-

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pad-

2 of 2

Sunrise Landfill Water Level ReadingsBoring/Well ID

PW12A

PW4A

PW13C

PW5C

MW 16A - 2"

MW 16A - 4"

PW6B

5W-6C-J

H7C

W15B

Date

3-

Time of Reading

&7S7

Depth to Water

. 73

Total Depth

252.5

484

810

29

802

470

174

275

154

625

2401

275

355

227

431

282

Name of Measurer

*5 , /yjj'&£fr?/i

4

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/J'/S/SS**?

•S* J&J'A'ts'A

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SCS ENGINEERSDAILY HELD NOTES

PROJECT NAME; Vfa>J»vkLi*LOCATION: L<cf>

TYPE OF NOTES:

SUBJECT:

/ MEETING / PHONE / OTHER

PROJECT* tQ\

PAGE I OF (

DATE; 1-

BY:

0701.-

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ATTACHMENT 2TABLES

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Table 1Sunrise Mountain Landfill

Preliminary First-Groundwater Water Table Elevation CalculationsMeasurements Taken February 6,2002

Well ID 1 Northing

MW-1AGH-1B (AB-1B)

PW-1CMW-2A (2")PW-2A (4")

PW-2BGH-2C (AB-2C)

PW-2C2 (2")PW-2C2 (4")

PW-2DPW-2D2MW-2EMW-2E2GH-2E3

GH-3A (AB-3A)GH-3B (AB-3B)

GH-3B2 (AB-3B2)GH-3C

GH-3CL (AB-3CL)GH-3D

*GH-3E (2")GH-3E (4")

PW-4APW-4BPW-4C

MW-5A (AB-5A)GH-5B (AB-5B)

GH-5B2 (AB-5B2)GH-5B3 (AB-5B3)

PW-5B4PW-5C

12493.529973.59

10215.97

10589.83

10053.23

10347.33

11925.39

Easting

14655.7014394.13

14215.41

13883.36

12184.47

10020.73

10377.22

WL Elev

1761.961691.00

1693.15

1698.43

1670.94

1677.37

1752.01

Well ID (Continued) | Northing | Easting

GH-6A (AB-6A)PW-6BPW-6C


GH-7CUGH-7CMGH-7CLPW-8AMW-8BPW-9APW-9B

PW-10APW-llA(2"inside4")

PW-11BPW-11CPW-12A

GH-12B (AB-12B)PW-12B2

GH-12C(AB-12C)PW-12D

GH-13A (AB-13A)GH-13B(AB-13B)

PW-13CMW-13DPW-14A

GH-15A (AB-15A)MW-15B

MW-16A(2")MW-16A (4")

TW-16B

14334.89

15570.11

13311.26

15980.12

10001.96

10164.02

11455.37

10624.90

14479.2012523.96

11342.74

12300.21

14711.82

13540.22

13250.34

11079.70

10210.00

14812.66

13103.3811859.49

WLElev

1761. 9(

1761.3S

1765.26

1762.65

1697.65

1679.2?

1703.17

1692.37

1764.741749.88

*Date Measured: 1/30/2002

F:\DATA\PROJECTSW00701.sunrise\TASK04HYDROGEOLOGJCSTUDY\GW CONTOUR 021802\FINALREPORT\GWContomv2

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Preliminary Second-Groundwater Water Table CalculationsMeasurements Taken February 6,2002

Well ID

MW-1AGH-1B (AB-1B)

PW-1CPW-2A(2")PW-2A(4")

PW-2BGH-2C (AB-2Q

PW-2C2J2")PW-2C2 (4")

PW-2DPW-2D2MW-2EMW-2E2GH-2E3




GH-3E (2")GH-3E(4")

PW-4APW-4BPW-4C



PW-5B4PW-5C

Northing

10553.0710596.91

10619.13

10362.84

Easting

13876.7613873.59

13867.88

10047.74

WL Elev

1697.551710.68

1624.95

1700.77

Well ID (Continued)GH-6A (AB-6A)

PW-6B (2" inside 4")PW-6C



PW-10APW-1 1 APW-11BPW-1 1CPW-12A



GH-13A(AB-13ALGH-13B(AB-13B)

PW-13CMW-13DPW-14A

GH-15A (AB-15A)MW-15B

MW-16A-2"MW-16A-4"

TW-16B

Northing

14324.90

13316.0815969.06

10011.40

10193.84

11433.97

12482.82

Easting

11360.85

14698.3513528.04

13264.54

11090.5

10142.58

11830.69

WL Elev

1761.07

1664.701755.62

1699.21

1717.81

1654.93

1720.30

F:\DATA\PROJECTS\9900701.sunrise\TASK 04 HYDROGEOLOGIC STUDTCW CONTOUR 021802\FINAL RfiPORT\GWContourv2

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Preliminary Deep-Groundwater Water Table CalculationsMeasurements Taken February 6,2002

Well IDMW-1A

GH-1B (AB-1B)PW-1C

PW-2A (2")PW-2A (4")

PW-2BGH-2C (AB-2C)

PW-2C2 (2")PW-2C2 (4")

PW-2DPW-2D2MW-2E

MW-2E2GH-2E3




GH-3E (2")GH-3E (4")

PW-4APW-4BPW-4C



PW-5B4PW-5C

Northing

10569.08

10353.21

12394.59

Easting

13885.96

10033.82

9751.63

WLElevj

1269.79

1706.85

1730.14

Well ID (Continued) | Northing | EastingGH-6A (AB-6A)

PW-6B(2"inside4")PW-6C



PW-10APW-1 1 A (2" inside 4")

PW-1 IBPW-1 1CPW-12A



GH-13A(AB-13A)GH-13B (AB-13B)

PW-13CMW-13DPW-14A

GH-15A(AB-15A)MW-15B

MW-16A-2"MW-16A-4"

TW-16B

9996.20

10195.04

13260.30

11114.63

WL Elev

1489.33

1689.90

F:\DATA\PROIECTSW900701.sunrise\TASK 04 HYDROGEOLOGIC STUDY\GW CONTOUR 021802\FINAL REPORT\GWContourv2

IIIII ATTACHMENT 3* FIGURES

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3RUARY 2002

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PRELIMINARY 1ST-OROUNDWATER CONTOUR CALCULMIONS

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PRELIMINARY 2ND-0ROUNDWATER CONTOUR CALCULATIONS


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PRELIMINARY DEEP-OROUNDWATER CONTOUR CALCULATIONS


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preliminary groundwater elevation contour maps

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