SFUND RECORDS CTR

2157331

Steve Wall/R9/USEPA/US To "Douglas Hamilton" <dhamilton@exponent.com>

07/11/2007 01:57 PM cc "Craig H. Benson" <benson@engr.wlsc.edu>, "Cliff

bcc

Anderson" <cliff(g)ahymo.com>, "Dave Betley" <dbetley@co.clark.nv.us>, "Gaddy, Alan"

Subject Re: Sunrise Landfill - Settlement-Confidential Negotiations-Las Vegas Paving Sample Analysis for Smaller Group Conference CalltJ

Sunrise Landfill - Settlement Confidential

For our call tomorrow, Doug asked me to send out the Las Vegas Paving sample analysis I mentioned in my email yesterday.

Las Vegas Paving Samples Critical slope, length, D50, and thickness analysis

I performed an analysis using the 5 Las Vegas Paving sample results and using the spreadsheet tool drafted by Cliff Anderson. For the critical slope and length for each side slope drainage area I found the 050 and calculated total thickness. The results of the calculations are shown in the attached file: sideslopes and thicknesses.xls

sideslopes and thicknesses.xls

I found that for half the slopes (the longer and steeper slopes) the bottom 50 to 260 ft needed between 0.5 and 4.5 inches of additional thickness vs. an optimal gradation and D50 for those slopes. These areas are shown as the hash marked areas on the attached topo map file: sidewall slope topo.pdf

sidewall slope topo.pdf

Plotting on the topo map shows that only 14 acres of the approximately 146 total sidewall acres, or 10% of the sidewall acres need an additional 0.5 and 4.5 inches to satisfy the criteria for the rip-rap veneer and granular filter layers (from SOW Task 4.1.4.1). This calculates to -t-7,000 to -1-8,000 cy compared to an estimated 175,000 to 200,000 cy for the entire 146 Acres of side slope erosion layer.

Steve Wall Office of Pollution Prevention and Solid Waste (WST-7) US EPA Region 9 75 Hawthorne Street San Francisco, CA 94105 415-972-3381 phone/415-947-3530 fax

"Douglas Hamilton" <dhanriilton(a)exponent.com>

"Douglas Hamilton" <dhamilton@exponent.com> To Steve Wall/R9/USEPA/US@EPA

07/11/2007 11:29 AM cc "Sandy Doty" <sandra.g.doty(a)saic.com>, "Cliff Anderson" <cliff@ahymo.com>, "Clarke Lundell"

<lundellc(5)repsrv.com>, "Gaddy, Alan" <GaddyA(a)repsrv.com>, "Layne Weber" <wlweber@co.clark.nv.us>, "Dave Betley" <dbetley@co.clark.nv.us>, "Jene LyIe" <jlyle@exponent.com>, "Craig H. Benson" <benson@engr.w/isc.edu>

Subject Sunrise Landfill - Settlement-Confidential Negotiations-Smaller Group Conference Call

Time: Thursday, July 12, 2007 11:00 am Pacific 2:00 pm Eastern

Dial in: 1-866-448-3976 Conference Code: 9493416016

Agenda: 1. Follow-up on previous Legal Technical call of 7-6-07 and review 3 spreadsheets sent out by Steve Wall on 7-10-07 regarding steeper than 10% slopes.

2. Discuss soil layer thickness and gradation for flatter than 10% slopes.

3. Discuss draft exhibit regarding certain side slope areas to be sent out by Steve Wall today.

Any problems call me at 949-300-5820

Additional documents for discussion may arrive in the morning preceding this phone call.

Doug Hamilton

Sunrise Sidewall Slopes 050 and Total Ttiickness based on On-sit Rock Crushing Results by Las Vegas Paving (LVP)

7/11/2007

Drainage Area E17 E9 El E2 E3 E4 B, C toe E7 E14 11 E16 Fitoe E15 E12 E6 E5 E l l E8 E10 E13

E6 top 300 E3, E4 E7 El E2 B, C toe

slope 0.05 0.07

0.1 0.1

0.12 0.12 0.15 0.11 0.29 0.23 0.18 0.25 0.15 0.16 0.20 0.23 0.28 0.20 0.22 0.31

% 0.13 0.12 0.11

0.1 , 0.1

0.15

critical slope length

400 900 200 300 250 250 200 500 350 400 500 400 650 700 600 550 475 650 650 500

300 250

200 300 200

Calc D50 veneer n/a veneer n/a

1.53 2.02 1.96 1.96 1.89 2.99

3.5 »W;».;Cfc-|i3;.77i

3.86

^ ^ ^ " ' ^ 3 ; 9 3

4.2

^ ^ ; 5 S r^^-6t -^&:,4.67^ F^^^-^4!69

4.87

» »

2.31 1.96

1.53 2.02 1.89

Calculated Thickness

6.0 6.0 6.0 6.0 6.0 8.5

10.0 10.5 11.0 11.0 11.5 12.5 12.5 13.5 13.5 14.0 15.0 15.0

6.5 6.0

6.0 6.0 6.0

with > 6 inch rock removed with > 6 inch rock removed with > 6 inch rock removed with > 6 inch rock removed assumes perimeter berm last 80 ft go from 7 to 8.5

with > 6 inch rock removed with > 6 inch rock removed

flat to steep at 300 ft - 400 last 40ft go from 10 to 11 toe at 300 to 400 ft last 40 ft go from 10 to 11.0 last 120 ft go from 10.0 to 11.5 last 195 ft go from 10.0 to 12.5 last 175 ft go from 10.0 to 12.5 last 170 ft go from 10.0 to 13.5 last 145 ft go from 10.0 to 13.5 last 230 ft go from 10.0 to 14.0 last 260 ft go from 10.0 to 15.0 last 200 ft go from 10.0 to 15.0

1.94 1.64

6.0 6.0

assumes perimeter berm

can go 305 at 6.0

1150 from top to toe 6in rock screen -get 13.5 in layer

^^mmiiwma\(/mm:Mm;mmms^mmammAij!m •

end of steepest point is 550 ft into slope length full drainage is 900 ft bottom 200 ft of 500 ft is at 28%

only last 40 ft over 14 inches only last 40 ft is over 14 inches

last 30 ft go from 6 to 6.5

perimeter berm at 300 ft??

6 up to 270 6 up to 290 6 up to 305 6 up to 330 6 up to 330

31 % from;