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Home My WebLink About20123294.tiff 3801 Automation Way Suite 100 It T E T RA TECH Fort Collins CO 80525 Tel 970.223.9600 .7171 .7171 ••••••••% • p • � S S'jO•%O ►/ i •V i , 45455 : Technical Memorandum _%i, O 0%7-12--3,%. /47% 0 Fs •••••. A% �, To: Jon Jaffe From: Caleb S. Stock, PE Company: Anadarko Petroleum Corporation Date: July 12, 2012 Re: Greater DJ Water Gathering—Gobbler Site Tt Project#: 114-182241 CC: Tom Chapel, PE, Lance Heyer, El, Dan Pastor, PE, and Nathan Keiser 1.0 introduction Anadarko Petroleum Corporation (Anadarko) retained Tetra Tech, Inc. (Tetra Tech) to perform the following tasks: • conduct a geotechnical investigation to characterize the subsurface for use in the design of an earthen water storage facility at the Gobbler site; • perform an engineering evaluation and cost analysis comparison of different process water storage alternatives; • design an earthen embankment and storage pit system to retain fresh water for use in hydraulic fracturing operations; • identify requirements for permitting the facility according to applicable regulations of the Colorado Oil and Gas Conservation Commission (COGCC) and other regulatory and municipality organizations; and • provide construction oversight during construction of the earthen water storage facility. This technical memorandum presents documentation and details of the design and analysis for facilities to store fresh water used in hydraulic fracturing operations, located in the northeast 1/4 of Section 23, Township 2 North, Range 66 West, Weld County, Colorado. The memorandum includes details of the geotechnical investigation of the site, assumptions made in the design and analysis, descriptions and details of the analysis methods used, referenced documents, and results, conclusions, opinions and recommendations regarding the Gobbler site and its development as an earthen retaining structure for water storage. 2.0 SITE AND PROJECT DESCRIPTION The Gobbler site is located approximately 7.6 miles southeast of Platteville, CO and approximately 4.0 miles east of U.S. Highway 85. Figure 1 shows a general location map. The site is generally flat, with a maximum elevation of 5155 feet near the center of the proposed facility and a minimum elevation of 5145 near the northwest, northeast, and southeast corners of the proposed pit, based on land surveying conducted by Petroleum Field Services, LLC. The facility site is located on undeveloped land which is currently vegetated with prairie grasses generally less than 0.5 feet in height. The facility is proposed to be constructed partially in-ground with earthen embankments above the existing ground surface, forming a storage impoundment for water used in hydraulic fracturing operations by Anadarko. The pit will be filled and emptied using a system of pumps and piping. Piping should be installed in such a way that it does not puncture or damage the geomembrane liner system. As required by COGCC Rule 902.b. the pit was designed to achieve the required capacity while maintaining 2 feet of freeboard; the pit will not include an emergency spillway. The pit will include a leak detection system (LDS) that will consist of a 60 mil liner, overlain by a HDPE geonet, overlain by another 60 mil liner. The geonet will serve to protect both liners from puncture and will collect water that penetrates the primary (top) geomembrane liner. The pit dimensions were selected to maximize height requirements, maximize storage capacity within the site restrictions, and balance earthwork cut and fill requirements. The footprint of the facility (including both pit and embankments) is approximately 15% acres with the pit being 350 feet by 770 feet from inside crest to inside crest. The crest of the pit embankments will be constructed between 5 and 9.5 feet above existing grade, making it a non-jurisdictional dam per the Colorado Division of Water Resources Rule 4.2.5.2. The storage capacity of the pit, assuming 2 feet of freeboard, will be approximately 500,000 barrels. The inside slopes of the pit will have 3 Horizontal: 1 Vertical slopes (3H:1V) and the landside slopes start at 50H:1V at the crest and transition to 5H:1 V moving away from the pit. The facility dimensions and positioning on site can be seen in Figure 2. Details for facility construction are discussed in the earthwork section of this memorandum. Final construction drawings and specifications will be provided prior to construction commencement. 3.0 GEOTECHNICAL INVESTIGATION AND SUBSURFACE CONDITIONS 3.1 Field Investigation On March 26, 2012, Tetra Tech drilled four exploratory borings to characterize the subsurface lithology, determine the in-situ moisture and density conditions, and obtain samples for laboratory testing. Locations for exploratory borings were identified during a site visit by members of Tetra Tech's design team and Anadarko staff on March 15, 2012. Approximate boring locations are shown on Figure 1 in Attachment A. The subsurface soils generally consisted of silty or clayey sands and low plasticity clays. Additional information regarding the subsurface geotechnical properties is presented in the following sections. 3.1.1 Soil Sample Collection Borings were drilled to a depth of 40 feet below the existing ground surface. The elevation, latitude, and longitude were recorded at each boring location using a hand-held GPS and are provided on the boring logs. Locations of the borings were also recorded by Petroleum Field Services, LLC. Geotechnical logs of each boring are provided in Attachment A. Greater DJ Water Gathering July 12, 2012 2 Drive samples up to 18 inches in length were collected during drilling at 5 foot intervals to the total depth drilled. During sampling, Standard Penetration Testing (SPT) was performed by driving a thick-walled sampler (California Sampler) containing brass liners into the soil using a 140 lb. weight falling approximately 30 inches. After "seating" the sampler into undisturbed soil, the blow count (N Value) was recorded as the number of blows required to drive the sampler 12 inches. The N Value was recorded on the logs and was used to categorize the consistency of the soil. Blow counts indicate the soil consistency of the fine-grained material is medium stiff to hard and the coarse grained material is loose to dense. Bulk samples were also collected during drilling in order to provide samples for re-molding to approximate properties that are representative of material that will be used in construction of the embankments. In general bulk samples were collected from auger cuttings on material ranging in depth from 0 to 14 feet below the existing ground surface. Two samples were collected on material type classified as low plasticity clay and gravelly sand, respectively. Additional information pertaining to in-situ moisture conditions, classification, laboratory compaction testing, and remolded shear strength, permeability, and swell-consolidation testing of embankment materials is discussed below. Samples were examined and visually classified. A laboratory testing program was designed to characterize and to identify key engineering properties of the soils to evaluate seepage potential and stability of the embankments for engineering design. Selected samples were tested in the laboratory for in-situ density and water content, gradation, Atterberg limits, swell and consolidation, compaction, permeability, and shear strength. Geotechnical properties and laboratory testing results are summarized in Table 1 (below) and a more detailed summary of each test is included in Attachment B. Subsurface characteristics are described in more detail below. 3.1.2 Subsurface Conditions & Laboratory Test Results All soil classifications discussed in the following sections were determined in accordance with ASTM D2487. In general, the soils encountered on site were alternating layers of clayey sand and low plasticity clay to depths between 10 and 14 feet below existing grade. These layers were underlain by gravelly sand or sand to a depth of between 19 and 25 feet. Gravelly sand and sand layers were underlain by weathered claystone bedrock and comparatively unweathered claystone bedrock to a drilling termination depth of 40 feet. Tt-7 encountered shallower claystone bedrock at a depth of 15 feet, and Tt-5 and Tt-8 encountered deeper claystone bedrock at depths of 24.5 and 25 feet, respectively, indicative of the elevation differences of the top of the borings (as shown in Attachment A). Six inches or less of topsoil- like material was encountered at the ground surface in all four borings. The "topsoil" layer did not contain abundant organic material. The upper subsurface zone including primarily clays and sands which will be the primary borrow source of fill used in embankment construction. The lower zone, where bedrock predominates will form the embankment foundation and will affect the flow of water from the pit, should the liner system be compromised during the life of the pit. The in-situ water content in the tested soil samples ranged from 2.2 to 18.7 percent and the in- situ dry density ranged from 88.9 to 129.7 pounds per cubic foot (pct). Atterberg limits testing indicated the liquid limit of the clayey soils ranged from 21 to 62 and the plasticity index ranged from 6 to 37. Grain size distribution testing was performed on twelve samples of varying depth in each bore hole. The results indicate that the upper 6 to 14 feet of the four boreholes contain similar amounts of sand and fine grained particles and are classified as clayey sand and lean clay. At a depth of approximately 5 feet below existing grade the fines (passing the No. 200 Greater DJ Water Gathering July 12, 2012 3 sieve) content of the subsurface increases significantly and classifications range from clayey sand to lean clay. Bedrock was classified as high plasticity clay and containing 93 percent fine sized particles (passing the no. 200 sieve). Standard compaction (Proctor) testing was performed according to ASTM D698 on two bucket samples collected from 0 to 7 and from 14 to 21 feet below existing grade. For purposes of this discussion, the sample from 0 to 7 feet will be called the shallow sample and the sample from 14 to 21 feet will be called the deep sample. Samples of similar materials from each bore hole were combined to provide representative samples of similar materials from the site. Proctor testing determined the maximum dry density and optimum water content of the shallow and deep samples to be 119.4 pounds per cubic foot (pcf) at 10.3 percent and 128.7 pcf at 9.0 percent, respectively. Adequate compaction of the embankments during construction will be determined relative to standard Proctor compaction testing, as indicated in the construction specifications. Two remolded direct shear tests were conducted on potential embankment material from the two bulk samples collected. Samples were remolded according to standard Proctor compaction testing to 95 percent of the maximum dry density and at the optimum water content. Test results indicate a total cohesion of 400 pounds per square foot (psf) with an angle of internal friction of 35 degrees for the shallow sample. A total cohesion of 980 pounds per square foot (psf) with an angle of internal friction of 28 degrees was determined for the deep sample. Three permeability tests were conducted: two remolded samples on potential embankment material from the two bulk samples collected (as described previously) and one on in-situ soils from boring Tt-7 at 9 feet. The two remolded samples were compacted based on standard Proctor compaction testing to 95 percent of the maximum dry density and a water content 1 percent less than the optimum. The remolded test using material from the shallow sample indicated a saturated hydraulic conductivity of 2.06E-4 centimeters per second (cm/s). The remolded test using material from the deep sample indicated a saturated hydraulic conductivity of 1.67E-5 centimeters per second (cm/s). The in-situ sample tested had a saturated hydraulic conductivity of 4.47E-4. Two swell-consolidation tests were performed, both on remolded potential embankment materials. The remolded samples were compacted to 95 percent of the maximum dry density and a water content of optimum based on standard Proctor compaction testing. Under an inundation pressure of 500 psf the remolded bulk samples from 0 to 7 and 14 to 21 feet bgs exhibited no volume change. The compression index (Ce) ranged from 0.04 to 0.05 and recompression index (Cs) was 0.02 for both remolded potential embankment samples. Overall, both samples were relatively incompressible over the range of applied vertical stresses investigated. Complete consolidation testing data can be viewed in Attachment B. Based on geotechnical laboratory investigations, the properties of both bulk samples indicate that they are both suitable for use as fill to construct earthen embankments. If properties of excavated materials deviate significantly from the two bulk samples tested, the engineer on site performing observation should immediately determine whether the material is adequate for use in the construction of the embankments. If materials are significantly different than those anticipated, the specifications may need to be revised relating to the ability to properly use and compact the materials. A more detailed description of embankment material and compaction guidelines is provided with the construction drawings and specifications. 3.1.3 Groundwater Greater DJ Water Gathering July 12, 2012 4 The four exploratory borings drilled at the site penetrated to a depth of 40 feet. At the time of drilling, water was not encountered in any of the boreholes. Tt-5 and Tt-8 were left open for a period of 24 hours to determine ground water conditions after drilling. Water was not encountered in Tt-5, but water was measured at 31 feet bgs in boring Tt-8 24 hours after drilling. An extensive study of the groundwater regime in the area was beyond the scope of this investigation; however we opine that the water which seeped into boring Tt-8 was from a porous, discontinuous sandstone lens within the claystone bedrock. We believe that the perched water encountered will have little to no effect on facility construction, operations, or sustainability. Greater DJ Water Gathering July 12, 2012 5 Table 1. Summary of Laboratory Test Results Sample Locaton and Type In-Situ Parameters Soil Classification Chemical Permeability Shear Strength Consolidation Proctor Properties Compaction Saturated In-Situ /n-Situ Dry Atterberg Gravel Sand Fines USCS Sulfate(ppm), Direct Inundation Boring Sample Sample Hydraulic Cohesion wopt(%), Water Density Limits Content Content Content Soil Chloride(ppm), Shear�° Pressure Cc,Cs Location Depth(ft) Type Content(%) (pcf) LL/PL/PI(%) (%) (%) (%) Class. pH Conductivity (Psi) (deg) (psf) Yd..(pcf) (cm/sec) _ Tt-5&Tt-7 0-7' Bulk 4.2 21/15/6 8.4 59.6 32.1 SC 2.06E-04 400 35 500 0.04,0.02 10.3,119.4 Tt-8 14-21' Bulk 4.0 22/16/6 3.7 59 37.4 SC 1.67E-05 980 28 500 0.05,0.02 8.8,128.8 Tt-5 9-10' CA 8.1 91.9 35/18/17 7.0 37.8 55.2 CL 63.1,9.2,9.74 Tt-5 19-20' CA 2.2 129.7 9.0 68.2 22.8 Tt-6 4-5' CA 14.0 98.8 36/24/12 1.7 39.1 59.3 CL Tt-6 9-10' CA 4.1 88.9 22/15/7 23.6 52.3 24.2 SC Tt-6 19-20' CA 18.7 109.8 60/27/33 4.1 95.9 CH Tt-7 9-10' CA 2.4 101.1 0.0 I 83.4 16.6 4.47E-04 Tt-7 19-20' CA 14.7 111.4 58/22/36 7.4 92.6 CH Tt-8 2-3' CA 8.2 109.0 24/18/6 0.0 69.7 30.3 SC Tt-8 9-10' CA 11.4 97.1 32/17/15 0.2 22.8 77 CL Tt-8 39-40' CA 17.6 117.0 62/25/37 7.2 92.8 CH Tetra Tech July 12, 2012 6 4.0 SEEPAGE AND SLOPE STABILITY ANALYSES Instability of earthen embankments used to retain fluids can occur by several mechanisms; three of which pertain to future site conditions and are listed below: 1. Water seeping through and/or under the embankments exiting on the downstream side with a velocity that is sufficient to mobilize soil particles (piping), resulting in destabilization. This mechanism can ultimately lead to failure of the embankment, or can contribute to slope instability if the condition is not corrected. 2. Decrease in shear strength of the embankment, or slope failure as a result of over- steepening of slopes due to erosion, piping, overtopping of the crest, construction practices or other factors. 3. Decrease in strength of the soil due to horizontal forces caused by seismic activity. To evaluate the potential for these mechanisms to contribute to instability of the embankments, Tetra Tech utilized the finite element computer modeling program SEEP/W to evaluate seepage conditions through and under embankments, and SLOPE/W to evaluate the stability of the embankment slopes. The most critical cross-section was identified based on the proposed design and the site survey of existing ground, and that section was analyzed for seepage and slope stability. For modeling purposes, the elevation of the fluid in the pit was assumed to be at the maximum design capacity (2 ft below the crest, freeboard elevation) and full (at the crest of the embankment). Although the pit will be lined, modeling scenarios omitted the liner system to simulate a worst case scenario in which a liner breach occurred, resulting in a steady state seepage scenario, reducing the stability of the embankments by increasing the unit weight of embankment materials and inducing seepage forces. 4.1 Design Guidelines Section 4.0 provides key assumptions that were made in the investigation and analysis of this embankment structure. Analysis of the embankment was conducted according to Natural Resources Conservation Service (NRCS) TR-60 criteria governing the design and construction of earth dams and reservoirs, although the pit embankments are less than or equal to 10 feet above existing grade at the embankment crest centerline and at the maximum section, which is under the height of a jurisdictional dam in the state of Colorado. TR-60, Table 5-2 recommends the minimum factors of safety, shown in Table 2 below. The horizontal acceleration used for the pseudo static analysis was 0.05g which corresponds to Peak Ground Acceleration (PGA) with 2 percent probability of exceedance in 50 years for this site according to the U.S. Geologic Survey (USGS) 2010 Earthquake Hazards Program Seismic Hazard Maps. Tetra Tech July 12, 2012 7 Table 2 Minimum Safety Factors for Slope Stability Analyses (NRCS TR-60, 2005) Scenario Minimum Factor of Location I Seismicity I Description Safety End of Construcion Upstream Static Failure extending into 1.4 foundation layers Downstream Static Failure isolated to 1.3 embankment layers Rapid Drawdown Upstream I Static I Any extensive failure* I 1.2 Steady State Seepage Upstream Static Any extensive failure* 1.5 Downstream Static Any extensive failure* 1.5 Upstream Pseudo-static Any extensive failure* 1.1 Downstream Pseudo-static Any extensive failure* 1.1 *Any extensive failure describes a failure surface compromising embankment stability (of significant depth relative to the embankment height)and yielding hazardous conditions 4.2 Input Parameters Laboratory testing was performed on samples collected during drilling operations as described above. Due to the uncertainty and variability of soils and the inherent differences normally observed between laboratory results and actual field conditions, engineering judgment and a measure of conservatism were applied to the laboratory results for their use in the computer models. A summary of laboratory test results is presented in Table 1 and the laboratory test results are presented in Attachment B. Table 3 presents the engineering properties of site soils used in the cross section modeled. Table 3. Model Input Material Properties Depth Unit Weight Hydraulic Shear Strength Soil Type Below Crest (lb/ft3) Conductivity Cohesion, Friction Angle, 0 (ft) (cm/s) c(psf) (deg) Embankment Clayey Sand 0-9.5 126 1.00E-04 75 20 Clayey Sand 9.5-16.5 115 5.00E-04 50 25 Lean Clay 16.5-25.5 105 5.00E-06 100 20 Gravel 25.5-31.5 125 1.00E-03 0 28 Claystone Bedrock 31.5-47 135 1.00E-08 200 24 4.3 Analysis The seepage and slope stability analyses were conducted on the most critical two-dimensional cross-section of the proposed embankment (see Figure 2). The most conservative cross-section was considered to include the highest elevation differential, steepest and longest slopes, and/or the weakest materials. As discussed earlier, all interior embankment slopes will be constructed at 3H:1 V and the exterior embankment will be either 5H:1 V or 50H:1 V. Tetra Tech July 12, 2012 8 The analyses were performed using the Seep/W and Slope/W components of GeoStudio 2007 by Geo-Slope International, Ltd (2007). Seep/W was used to conduct steady state finite element seepage analyses. The size of the finite element mesh in the seepage model was set to 1.0 feet. Constant boundary conditions included a potential seepage face, fluid total head elevation, and ground water levels measured in exploratory borings after drilling. A steady state seepage analysis implies that the seepage occurred over a period of time sufficient enough to fully define the phreatic surface and provide continuous seepage magnitudes at all locations through and under the embankments. The static condition describes the normal, long term operating levels of the pit. Rapid drawdown occurs when the pit has achieved a steady state and constant phreatic surface, and then the water surface elevation is rapidly lowered such that the saturated embankment is no longer supported by hydrostatic pressures. The pseudo-static condition adds an additional horizontal loading condition occurring due to seismic loading. The pseudo-static magnitude was determined using a U.S. Geologic Survey (USGS) seismic risk maps for the area. 4.3.1 Seepage Seepage analyses were performed on the critical cross sections of the pit embankment to evaluate the performance of the embankment, and estimate seepage flux, or volume of seepage per time, on the downstream side of the embankment, and to estimate pore pressure conditions within the embankment for use in slope stability analyses. The HDPE liner was neglected in the analysis for conservatism, as discussed above. The fluid level was modeled at the freeboard elevation and at the maximum embankment height, which are approximately 13 ft and 15 ft above the base of the earthen impoundment, respectively. These surface elevations were selected for modeling because they represent the critical design water elevations for this facility. For this pit the fluid was assumed to be fresh water with a specific gravity of 1.0. An alteration in the fluid specific gravity will have little effect on the final results. A fluid specific gravity up to 1.25 provides factors of safety above the required limits (Table 2). Boundary conditions equal to the respective water heights were applied on the upstream face of the embankment while the boundary condition of a potential seepage face was applied to the downstream face of the embankment. 4.3.2 Slope Stability Stability was analyzed using limit equilibrium principles. Potential failure surfaces were analyzed using the Spencer method, which satisfies both force and moment equilibrium in and between slices. The Slope/W program incorporates a search routine to locate the failure surface with the lowest factor of safety within user defined search limits. Trial failure surfaces were defined with "entry and exit" parameters, resulting in a range of possible locations to search for the critical potential failure surface (lowest factor of safety). Analyses were performed using Mohr-Coulomb failure criteria for the soil materials. For the pore pressure conditions, the steady state seepage files from SEEP/W were used as the parent analysis for the analyses' input data, except for the rapid drawdown case where the phreatic surface was drawn manually to indicate the dividing line between saturated and unsaturated conditions, as discussed above. Slope stability analyses were performed for both Tetra Tech July 12, 2012 9 upstream and downstream side slopes, assuming static and pseudo-static seismic loading conditions, for fluid at freeboard elevation and at the maximum embankment elevation, and for the upstream, static, rapid drawdown scenario as described above. 4.4 Seepage Analyses Results Detailed computer output illustrating the results of seepage analyses for the pit embankment at maximum design (freeboard) elevation and at crest elevation are included in Attachment C. The seepage flux was determined at the downstream toe of the modeled embankment, at the location most susceptible to piping. The results of seepage modeling are presented in Table 4, below. Table 4. Liquid flux at the downstream toe of the modeled pit embankment and topsoil stockpile Cross-Section Scenario Liquid Flux(ft /s) Pit Embankments Crest Elevation 6 8E-06 Pit Embankments Freeboard Elevation 5.0E-06 The results shown in Table 4 imply that the volume of seepage through the embankment, per foot of length of embankment, is negligible and will not yield problematic piping. Seepage analyses were conducted for the embankments assuming a no liner condition, simulating a total liner failure which is an unexpected and conservative assumption. The seepage flux was approximately equal for both water surface elevations modeled. These results indicate minimal risk of seepage related failures, even for unlined embankments. The hydraulic gradient of the downstream slope at the toe of the embankment (the location most susceptible to piping) was calculated to be 0.354. According to methodology recommended by the USACE, the factor of safety against piping caused by an excessive hydraulic gradient can be calculated as the critical hydraulic gradient divided by the measured hydraulic gradient. The critical hydraulic gradient is the ratio of the buoyant unit weight of soil to the unit weight of water. For our calculations, a conservative moist unit weight of 126 pcf was applied at the toe of the embankment resulting in a critical hydraulic gradient of 1.7. Thus, the factor of safety against piping was calculated as 4.9. These calculations indicate a low risk of embankment distress or failure due to seepage. 4.5 Stability Analysis Results The stability analyses incorporated the pore pressure results from the seepage analyses described in the previous section. Table 5 presents the results of the slope stability modeling for the critical portion of the pit embankment. Upstream and downstream slopes were analyzed for pit embankments. Conditions analyzed for slope stability included the following scenarios: • Downstream at freeboard elevation, static • Downstream at freeboard elevation, pseudo-static • Upstream at freeboard elevation, static • Upstream at freeboard elevation, pseudo-static • Downstream at crest elevation, static • Downstream at crest elevation, pseudo-static • Upstream at crest elevation, static • Upstream at crest elevation, pseudo-static Tetra Tech July 12, 2012 10 • Upstream from crest elevation with rapid drawdown, static Table 5. Summary of Factors of Safety for Slope Stability Scenario Cross- Factor of Section Location Seismicity Horizontal Seismic Safety Coefficient End of Construcion Upstream Static - 2.2 Downstream Static — 2.7 Upstream Pseudo-static 0.05 1.9 Downstream Pseudo-static 0.05 2.3 Crest Elevation Upstream Static - 2.4 Downstream Static — 1.6 Upstream Pseudo-static 0.05 1.8 Downstream Pseudo-static 0.05 1.3 Rapid Draw Down from Crest Elevation Upstream Static - I 1.9 Freeboard Elevation Upstream Static - 2.2 Downstream Static — 1.8 Upstream Pseudo-static 0.05 1.7 Downstream Pseudo-static 0.05 1.5 The results of the analyses indicate that the embankment slopes meet or exceed the minimum factors of safety recommended by NRCS for small earthen dams. The highest factors of safety were calculated for static conditions; the lowest factor of safety, 1.3, was produced by the downstream, pseudo-static, crest elevation scenario. The psuedo-static results also meet or exceed the minimum factors of safety. These results indicate that for the conditions modeled, the design embankment slopes are stable. Detailed computer output illustrating the results of the slope stability analyses for the pit are presented in Attachment C. 5.0 CIVIL ENGINEERING DESIGN A location was identified by Anadarko and investigated as described above to determine the suitability for construction of a facility to be used for storage of water. A minimum capacity of 250,000 barrels was specified by Anadarko, but a preference was specified to maximize the design capacity to the extent possible given site conditions. The final design capacity is approximately 500,000 barrels assuming 2 feet of freeboard is maintained. The design was prepared in accordance with the Colorado Oil and Gas Conservation Commission requirements and generally accepted engineering practices. 5.1 Layout and Capacity As designed, the Gobbler site pit is a rectangular structure with interior dimensions of approximately 350 feet by 770 feet. The interior slopes are 3H:1 V. To balance the excavation and fill quantities as closely as possible, the crest was set at approximately 5 to 9.5 feet above Tetra Tech July 12, 2012 11 existing grade and exterior slopes are either 5H:1 V or 50H:1 V. The pit floor slopes at one percent towards the northeast, and a 22 feet by 22 feet by 3 feet sump is planned at the northeast side midpoint to collect seepage through the primary liner. The pit will have an overall depth from the crest to the floor of the pit of approximately 15 feet. The crest elevation does not exceed 10 feet above existing grade in any location. A depth versus capacity curve is provided on the drawings. After construction of the embankments, an adequate fence and gate system should be installed around the embankment perimeter. Anadarko has indicated they plan to install a 5 strand barbed wire fence. Weather and UV-resistant safety lines with floats should also be planned for as a safety feature in the event of accidental entrance into the impounded water by workers. Geotechnical investigation of the site encountered minimal topsoil in all four of the borings. Prior to excavation and fill, the upper 6 inches of soil should be stripped from the ground surface below the facility footprint. This material should be temporarily stockpiled as topsoil at the location shown on the drawings. Following construction and grading of the embankment, the topsoil can be temporarily placed 11 inches thick on the exterior slopes of the embankment. During closure the topsoil should again be moved to a temporary stockpile then replaced as the final ground surface. 5.2 Earthwork Prior to placing fill, the bases of those areas to receive fill should be scarified, moisture treated to within two percent of optimum water content, and compacted to at least 90 percent of standard Proctor maximum dry density (ASTM D 698). Fill should be mixed to a uniform consistency, placed in maximum loose lifts not to exceed 12 inches, moisture treated to within three percent of optimum water content and compacted to at least 95 percent of standard Proctor maximum dry density (ASTM D 698). Based on exploratory drilling, we anticipate that materials excavated from the pit will be primarily silty, clayey sand, and lean clay. A geotechnical engineer or their designated representative should observe the construction process to identify material types, test for percent compaction and moisture, and provide recommendations during construction. Fill used in embankment construction should be compacted to a minimum of 95 percent of their maximum dry density and within three percent of their optimum water content based on standard Proctor compaction testing. 5.3 Geomembrane Liner For impoundments of this size and planned use, COGCC regulations require a geomembrane liner at least 24 mil thickness that is installed by a certified contractor. Tetra Tech recommends a liner system incorporating a 60 mil HDPE secondary (lower) liner, overlain by a HDPE geonet, overlain by a 60 mil primary (upper) liner for this site. The liner material must be compatible with the intended fluid storage and should provide UV protection for the intended design life of the facility. The liners should be installed as a continuous system; all seams should be welded or extruded according to manufacturer recommendations. Seams should not be sewn. The geomembrane liner will be anchored at the crest of the embankment using an anchor trench 18 inches deep and constructed in accordance with COGCC 904.c.(1). A depth measurement system is proposed that will provide markings at one foot intervals and large (2 foot) white numerals every 3 feet extruded on to the black liner material such that the depth of the fluid in the pit is easily discernible. If it is desirable to reduce evaporative losses, a Tetra Tech July 12, 2012 12 white primary liner could be used. In this case, black letters and markings would be extruded onto the white liner surface. 5.4 Freeboard An important aspect of embankment stability and performance is maintaining the appropriate freeboard (the vertical distance from the water surface to the crest of the embankment). If the freeboard is insufficient, the embankment could overtop, leading to excessive erosion and possible failure. COGCC regulations require a minimum freeboard of 2 feet for the proposed pit. Calculations were performed in order to determine the freeboard for this facility and to verify that 2 feet is adequate to protect the pit from overtopping due to wind and wave action. Since the pit is considered to be a small water body and will have a water surface length less than 1 mile, "standard" calculations for determining the wave height were not considered appropriate. Therefore, the wave height was calculated based on methods described by Julien (2006). A maximum wave height of 1.1 feet for standard operation was calculated. Wave run-up and wave set-up were calculated based on figures and equations provided in "Hydraulics of Dams and Reservoirs" (Sent(irk, 1994) and were determined to be insignificant (<0.1 feet). A design wind speed of 90 mph was suggested by the Bureau of Reclamation for determining the operational design freeboard and a wind speed of 50 mph for determining the minimum freeboard. In determining the operational freeboard, total heave or settlement (discussed below) was incorporated in the freeboard analysis, and indicate that the operational freeboard should be at least 2 feet at any given time. Therefore the COGCC minimum requirement of 2 feet was determined to be appropriate and was used in the design. 5.5 Settlement of Embankment Materials Settlement of embankment material is an important aspect of embankment stability and total fluid storage potential. Consolidation-swell tests were conducted on representative samples of embankment material to provide differential strain measurements upon inundation and with differing applied vertical stresses. Consolidation-swell testing provides measurements of swell and compressibility. Testing indicated that embankment materials were non-expansive. These values are used to estimate the amount of settlement that can be expected in the embankment materials post compaction. As discussed in Section 3, consolidation-swell samples were compacted to 95 percent of the maximum dry density and at the optimum moisture content based on standard Proctor compaction testing, which will provide a valid representation of the swell-compression behavior given the boundaries specified for embankment compaction (greater than 95 percent of the maximum dry density and within ±3 percent of the optimum moisture content). The behavior of the soils at the site was analyzed in accordance with volume change theory and general settlement calculations (Budhu, 2011). The embankment and foundation soils were subdivided into layers according to similar consolidation characteristics and material classifications. The differential vertical height change of each layer was calculated based on laboratory test results, experience with similar materials, and overburden soil and water pressures. The net vertical height change was analyzed for the embankment height relative to existing grade to determine potential discrepancies in storage due to differential settlements. The total settlement of the entire facility to a depth of 50 feet below the final crest elevation was calculated to be 3.8 inches. The differential settlement of the embankment portion was Tetra Tech July 12, 2012 13 calculated as less than 0.1 inches and will not have insignificant effects on the overall facility storage system. The freeboard calculations for the pit are based on embankment subgrade with no allowance for a road base. 5.6 Permitting and Closure A permit application Form 2A should be filed with the COGCC in accordance with COGCC regulations prior to construction. Upon approval of the application, construction in accordance with COGCC regulations and the design drawings is recommended. At the completion of the facility life cycle, closure is required. 6.0 CONCLUSIONS Geotechnical and civil engineering investigations indicate the proposed Gobbler site is suitable for construction of the proposed facility as described herein. The design and investigation were based on four soil borings, and variation in subsurface conditions should be anticipated. Construction should be conducted in accordance with COGCC regulations, the design drawings, and this report. We believe this investigation was conducted in a manner consistent with generally accepted geotechnical and civil engineering principles and according to methods normally used in the vicinity of the project at this time. No warranty is made, express or implied. Should additional information become available that could alter the analyses, conclusions, or recommendations in this report, Tetra Tech should be contacted to review the design documents in the light of that information to determine if revisions are needed. Tetra Tech July 12, 2012 14 7.0 REFERENCES Budhu M., 2011. Soil Mechanics and Foundations. John Wiley& Sons Inc., Hoboken, NJ. Geo-Slope International, Ltd. (GEO-SLOPE). 2007. "Geostudio 2007" Version 7.13. Calgary, Alberta, Canada. Julien, 2006. River Mechanics. Cambridge University Press, New York. 395pp. National Resources Conservation Service (NCRS). 2005. Earth Dams and Reservoirs TR-60. Nelson and Miller, 1992. Expansive Soils, John Wiley & Sons, Inc., New York. 99pp. Senturk, 1994. Hydraulics of Dams and Reservoirs. Water Resources Publications, Colorado. 420pp. U.S. Geologic Survey (USGS). 2010. Earthquake Hazards Program. Seismic Hazard Map, http://earthquake.usgs.gov/earthquakes/states/texas/hazards.php. Viewed April 20, 2010. Tetra Tech July 12, 2012 15 FIGURES Tetra Tech July 12, 2012 M Weld Co. Fort Collins. Greeley 1 • I. .F.,.... .... \ DENVER \ io zs W Colorado Springs 1 Colorado r Pueblo / / ' / 1 / / J Weld County N Q , O N o \--. , r` 1 , l • w o• O 's ttl� Jo ir � 11 ai o 2 f OBBLER, a o 66 ITE 6 N CJ s !I! 1521 . cs f EE O N I 2 Issued by: Prepared for. File Name: Anadarko Gobbler-Location.d�vg p q Figure 1 TETRA TECH `Project: Project Number: N IMI 3801 Autom ation Way,Suite 100 Greater DJ Basin 114-182241 Gobbler Water Storage Facility N Fort Collins,Colorado 80525 (970)223-9600 I i Proect Location: Date of Issue: General Location Map 970 223-7171 faK j Platteville,CO 7/12/2012 \L) L)-445) SECTION 23 E D /Q -N, R66W � /,// ti 5125oll)11-1 f CNI , �o S- Cr4,W/LA' I ,mss I! -X h < \"5 �I�/ PERT METE fE� f _ AI j }} (5 ST AND ABA �EED=-WfR � � ii M M -_- - 145x / 4i/ 1, �� / 5150 / (,1 11} Ø C/ , T �1IyyI ;k / / 5 , 1ti� , \ ACCESS n - ig ' �_� • ,_ _ - r ti'1'y,ti1yj1 � I 5 �. 1,115 — 4c5//// ! WATST0R • E p1 .� _) ILITY � i ` X a }I � ��4-k. PROPOSED tc, x STORAGE N ,11}} , � — , x X AC I L TY x F -------------E_17_, l N }} a _ x`.1 4 // i ! \, _ � �-� � � � 7 �iSTA��i pro � ' f:_,-)� / Erxdti�zOVERH _ID � , /2R9P YJ �N 4 ', I I L� TF� C coo " \a�J I •—9 --P FP ELI JL'r I �`�� - /� IN ____,y -------------- - 2 LEGEND 1�T o 11EE =R TING CON ��`— \-\\:\ POSD C / t I I +� .A y • , \Z3 — — — — ION LINE c) DI f i --TT/2N- NR ----- PIPELINE EASEMENT IP �� \ I 1/4 SECTION CORNER o 1 �.. SCALE I I l Il MODEL SECTION 100' zoo' -/ CONTOUR INTERVAL 1 FT. cs 'I 2 Issued by: Prepared for: File Name: Anadarko Figure2•Uw9_I el Figure 2 TETRA TECH Project: Protect Number: N 380fAatomaaonWay,Sudefoo Greater DJ Basin 114-182241 Gobbler Water Storage Facility N For:Collins,Colorado 80525 J ( J Project Location: Nate of Issue: Site Layout 970 223�fi00 970 223.7777 fax j Platteville,CO 7/12/2012 I ATTACHMENT A BORING LOGS Tetra Tech July 12, 2012 ,___ ___________________ \,Ni \ i ,,r) -SECTION 23 r1 I \ N, R6i?W \ 1 I tf �i in / //, �� I 5125- �° // / Ili s, II �j / i�II 47 1 mot,, _- f —X- �"�-) I\, s I -E-E r,I '' ( 1 } / �4P ` ----1—'77::::::::": •�} xa— x ' _ x �11 / _ - 145— �x�\ �, I ", 1} 150 (ii'li'l-ll'ivi'::i 1 l}1' } l/h � - -� � � ~ 1,1 1 P 'c//�;% �F� �J��5 , ,1',,tiyy'1}} f 1 rX Lo 55 r � \\,\\ ,�,'` _ 'z / \��(\ IC)� Tt,7 r' " WAT - TOR E ��titi�� ILITY / ) / 71 • t- /I } X 1� •; 1 �� i t-p ;` / I Q 1} f - � x PROPOSED N I x STORAGE \ 11 x , �. x x 1 -_FACILITY /�11 _ .-------'7' __/i 1 / I II / i 7 � � 7 EX1,6TYN R A� I \ �\ \� / �}. Q bl ��C �\ / \ II I G-761-1--17,'PE-) I __� - yy < ii -A-5, MEN .4_ _.7 ____7__ _______--------__ -ffrc- r----1---- _,_ - �i ,III � LEGEND 1' �� • BOREHOLE LOCATION ��` EXISTING CONTOUR 1 ��-- \ , PROPOSED CONTOUR I ( /I "'1`/--~~ T 23 - - - - SECTION LINE c.) D I/ I f -�c2N\ R 7tI I r�\�, 1 L, PIPELINE EASEMENT cs\ I 0- 1/4 SECTION CORNER SCALE 1 JJ A• 1 100' o .100' zoo' -9 I CONTOUR INTERVAL 1 FT. 12 Issued by: Prepared for: File Name: Anadarko Figure1-Attdwg Attachment A - Figure 1_I Ell TETRA TECP Pro]ect: ProJec1 Number: N 3801 Automation Way,Suite 100 Greater DJ Basin 114-182241 Gobbler Water Storage Facility N Fort Collins,Colorado 80525 (970)22343S00 (970)223.7171 fax PraJ.ct Location: Date of lane: Borehole Locations Platteville,CO 7/12/2012 Tetra Tech MM BOREHOLE ID: Tt-5 350 Indiana Street,Suite 500 PAGE 1 OF 1 'Kt TETRA TECH Golden,CO-80401 Telephone: 303-217-5700 Fax: 303-217-5705 CLIENT Anadarko PROJECT NAME Greater DJ Water Gathering(Gobbler Site) PROJECT NUMBER 114-182241 PROJECT LOCATION Weld County,CO DATE(S)OF DRILLING:04/20/2012 ELEVATION:5144 ft* METHOD:HSA CONSULTANT:Tetra Tech LATITUDE:040.126661 N* LOGGED BY:Lance Heyer DRILLING CONTRACTOR:Drilling Engineers LONGITUDE:104.736342 W* DRILLED BY:Andy Notes:Recorded by hand-held GPS W o F- 2 ui ~ W = J O TESTS U• O MATERIAL DESCRIPTION o � O O j �� Q O W m O 0 1.0 TOPSOIL 5143.0 - - l •• \ clayey sand, loose,dry, light brown - - CLAYEY SAND - - ,: moist, loose, low plasticity, light brown 5- 7N1MC 100 3-4 MC=7.3% 7.A _ _ 8.0 5136.0 LEAN CLAY - 1• 0 MC 100 12-14 MC=8.1% moist,stiff, light brown, calcareous,with sand DD=91.9 pcf LL=35.0 — — PL=18.0 CL Fines=55.2% — 1• 5 MC 100 26-44 14.5 5129.5 CLAYEY SAND _ _ • dry,stiff, medium plasticity, light brown _ 111190 5125.0 MC=2.2°i° J ` GRAVELLY SAND 2• 0 MC 100 15-24 DD=129.7pcf Fines=22.8% dry,dense,grey to pink,with trace fines o � 0- - w J J I — 24.5 5119.5 25 MC 100 14-27 WEATHERED CLAYSTONE BEDROCK Q_ _ moist,very stiff, high plasticity,grey to black, iron oxide staining �- - 0 z E- _ 29.0 5115.0 30 MC 100 17-37 CLAYSTONE BEDROCK moist, hard, high plasticity,grey to black, iron oxide staining 0- - w- - J CO - ° 35 MC 100 12-27 0 Q- - z - - H 40 } MC 100 16-39 40.0 5104.0 Bottom of hole at 40.0 feet. 0 0 W 0 Tetra Tech MM BOREHOLE ID: Tt-6 350 Indiana Street,Suite 500 PAGE 1 OF 1 'Kt TETRA TECH Golden,CO-80401 Telephone: 303-217-5700 Fax: 303-217-5705 CLIENT Anadarko PROJECT NAME Greater DJ Water Gathering(Gobbler Site) PROJECT NUMBER 114-182241 PROJECT LOCATION Weld County,CO DATE(S)OF DRILLING:04/20/2012 ELEVATION:5140 ft* METHOD:HSA CONSULTANT:Tetra Tech LATITUDE:040.126314 N* LOGGED BY:Lance Heyer DRILLING CONTRACTOR:Drilling Engineers LONGITUDE:104.736692 W* DRILLED BY:Andy Notes:Recorded by hand-held GPS W o F- 2 u5 ~ W O = J > U TESTS U• O MATERIAL DESCRIPTION o o_ O O j gJ Q W m0 O 0 1.0 TOPSOIL 5138.5 \ clayey sand, loose,dry, light brown LEAN CLAY - - stiff, moist, light brown, calcareous - 5 MC 100 10-16 MC=14.0% DD=98.8pcf CL LL=36.0 — — PL=24.0 I Fines=59.3% — ,9.0 5130.5 1• 0 MC 100 12-16 MC=4.0% CLAYEY SAND DD=88.9 pcf moist, medium stiff, low to medium plasticity, light brown LL=22.0 p y, 9 - - PL=15.0 SC ,•: Fines=24.2% _ _ ,•,13.0 5126.5 GRAVELLY SAND 1• 5 MC 100 16-18 dry,dense,grey/pink,with trace fines _ _ _ 19.0 5120.5 2• 0 MC 100 16-16 MC=18.7% WEATHERED CLAYSTONE BEDROCK DD=109.8pcf m LL=60.0 weathered claystone bedrock, moist,very stiff, high plasticity,grey to o- - PL=27.0 CH black, iron oxide staining 0 w- - Fines=95.9% 24.0 5115.5 25 MC 100 10-17 CLAYSTONE BEDROCK claystone bedrock, moist,very stiff to hard, high plasticity,grey to - - black, iron oxide staining - - 0 z E- - a 30 MC 100 21-46 0 0- - w- - CO CO ° 35 MC 100 21-50/4" 0 a Q- - z - - H 40 } MC 100 15-32 40.0 5099.5 Bottom of hole at 40.0 feet. 0 0 W 0 Tetra Tech MM BOREHOLE ID: Tt-7 350 Indiana Street,Suite 500 PAGE 1 OF 1 "Et TETRA TECH Golden,CO-80401 Telephone: 303-217-5700 Fax: 303-217-5705 CLIENT Anadarko PROJECT NAME Greater DJ Water Gathering(Gobbler Site) PROJECT NUMBER 114-182241 PROJECT LOCATION Weld County,CO DATE(S)OF DRILLING:04/20/2012 ELEVATION:5141 ft* METHOD:HSA CONSULTANT:Tetra Tech LATITUDE:040.126969 N* LOGGED BY:Lance Heyer DRILLING CONTRACTOR:Drilling Engineers LONGITUDE:104.736761 W* DRILLED BY:Andy Notes:Recorded by hand-held GPS W o>- F- 2 u5 ~ Lu = J O U TESTS U• O MATERIAL DESCRIPTION Lu a o_ O O j g_i Q O W m O 0 1.0 TOPSOIL 5140.0 • •• \ clayey sand, loose,dry, light brown NI MC 100 3-4 CLAYEY SAND ,.: very loose to loose, moist, low plasticity, light brown,with silt - 5 MC 100 3-2 , _ _ . ..• 6.0 5135.0 LEAN CLAY soft to medium stiff, moist, low to medium plasticity, light brown, - - calcareous - 10 MC 100 1-10 Fines=16.6% 10.0 5131.0 POORLY GRADED SAND moist, medium dense, low plasticity, light brown, <5%fines,with trace - - fines - 15 MC 100 5-8 15.0 5126.0 WEATHERED CLAYSTONE BEDROCK weathered claystone bedrock,moist,stiff to hard, high plasticity,grey - - to black, iron oxide staining 12-41 20 MC=14.7%MC 100 DD=111.4 pcf LL=58.0 — — PL=22.0 Fines=92.6% Q- - CH ,u2 25 -NI MC 100 13-24 — - 0 z _ / 0 30 MC 100 50/3" 30.0 5111.0 0 -- 31.0 SANDSTONE 5110.0 - \ dry,very dense, medium plasticity, red, iron oxide staining,with clay - - CLAYSTONE BEDROCK LIJ - - moist,very stiff to hard, high plasticity,grey to black, iron oxide _ _ staining ° 35 0 a Q- - Z - - H 40 MC 100 12-34 140.0 5101.0 Bottom of hole at 40.0 feet. 0 0 W 0 CO Tetra Tech MM BOREHOLE ID: Tt-8 350 Indiana Street,Suite 500 PAGE 1 OF 1 'Kt TETRA TECH Golden,CO-80401 Telephone: 303-217-5700 Fax: 303-217-5705 CLIENT Anadarko PROJECT NAME Greater DJ Water Gathering(Gobbler Site) PROJECT NUMBER 114-182241 PROJECT LOCATION Weld County,CO DATE(S)OF DRILLING:04/20/2012 ELEVATION:5138 ft* METHOD:HSA CONSULTANT:Tetra Tech LATITUDE:040.126717 N* LOGGED BY:Lance Heyer DRILLING CONTRACTOR:Drilling Engineers LONGITUDE:104.735581 W* DRILLED BY:Andy Notes:Recorded by hand-held GPS W o I— I >- o~ D u5 U W = a_= J > O U TESTS U• O MATERIAL DESCRIPTION o o_ O O j g_i Q W m0 ( O 0 .0 TOPSOIL 5136.5 - - .W 1 \ clayey sand, loose,dry, light brown - NIMC=8.2% CLAYEY SAND MC 100 4-6 DD=109.0 pcf SC loose to medium dense, moist, low plasticity, brown,well-graded,with LL=24.0 '' - PL=18.0 4.0 , trace clay 5133.5 5 MC 100 7-14 Fines=30.3% // LEAN CLAY moist, medium dense, medium plasticity, light brown,with sand- - //- 10 N MC 100 7-14 MC=11.4% CL DD=97.1 pcf LL=32.0 4 — — PL=17.0 Fines=77.0% 14.0 5123.5 - 15 N MC 100 14-22 GRAVELLY SAND _ - dry,dense, low plasticity,white to pink,with trace fines 20 }4 MC 100 18-24 `c_ — �� 21.0 5116.5 o Pt.'...79, POORLY GRADED SAND O- - moist,very dense, low plasticity,grey to pink,poorly graded,with - - � trace fines a A - 1 •4k W 25 MC 100 16-50/5" 25.0 5112.5 a WEATHERED CLAYSTONE BEDROCK o- - moist, hard, high plasticity,grey to black, iron oxide staining .- - 0 z E- - a 6 30 N MC 100 36-50/5" 0 - - 7 Depth of water measured 24 hours after drilling 0- - w- - m CO_ - ° 35 0 Y .- - 0 37.0 5100.5 zCLAYSTONE BEDROCK - - H_ CH moist, hard, high plasticity,grey to black, iron oxide staining 40 MC 100 24-50"/1" MC=17.6% DD=117.0 pcf , 40.0 5097.5 w LL=62.0 Bottom of hole at 40.0 feet. ri PL=25.0 F- Fines=92.8% w J 0 I 0 CO ATTACHMENT B LABORATORY TESTING RESULTS Tetra Tech July 12, 2012 PERMEABILITY TEST REPORT TEST DATA: SAMPLE DATA: Specimen Height (cm) : 6.02 Sample Identification : Tt-7 9 ' -10 'A Specimen Diameter (cm) : 4.93 Dry Unit Weight (pcf) : 101 . 1 Visual Description : Moisture Before Test (%) : 2.4 Moisture After Test (%) : 0.0 Remarks: Run Number : 1 • 2 1 Cell Pressure (psi ) : 65.0 Maximum Dry Density (pcf) : Optimum Moisture Content (%) : Sat . Pressure (psi ) : 60.0 Diff . Head (psi ) : 1 .0 Percent Compaction : Permeameter type: Flexwall Perm. (cm/sec) : 4.47x 10--4 Sample type : Undisturbed TIME - t (sec) 0 250 500 750 1000 0 \\*\ 10 20 0 30 0 40 50 N• 1 x 10^-3 \ 8 x 10^-4 E 6 x 10^-4 4 x 10^-4 H • 2 x 10^-4 07 W w 1 x 10^-4 10 15 20 25 30 AVERAGE HYDRAULIC GRADIENT - dH/L (cm/cm) Project : Greater DJ Water Gathering Gobbler Project No. : 114-182241 Location : File No . : 23. 7 Date: 5/9/2012 Lab No . : Tested by : PERMEABILITY TEST REPORT Checked by : TETRA TECH Test : FH - Fa l I i ng head C Particle Size Distribution Report o00•C C C C .C ! O O O O O O 7 O (O C') N " 0 M rt Tk N 4k a # 4. 4k 4k 100 0 I I I I 90 10 I t I 80 ; I 20 70 30 W m W 60 40 0 z m m z z 50 50 n W O U D ii 40 1 60 � I 1 m 30 - 70 I I I 20 - 80 I I I I I I I 10 I I I I I 90 I I I I 0 J I I I 100 100 10 1 0.1 0.01 0.001 GRAIN SIZE-mm. %Gravel %Sand %Fines %+3„ Coarse Fine Coarse Medium Fine Silt Clay 0.0 0.0 0.0 0.0 10.2 73.2 16.6 SIEVE PERCENT SPEC.* PASS? Material Description SIZE FINER PERCENT (X=NO) #20 100.0 #40 89.8 #80 47.1 Atterberg Limits #200 16.6 PL= LL= P 1= Coefficients D90= 0.4270 D85= 0.3741 D60= 0.2302 D50= 0.1907 D30= 0.1172 015= 010= Cu- Cc= Classification USCS= AASHTO= Remarks * (no specification provided) Source of Sample: Tt-7 Depth: 9'-10'A Date: Tetra Tech, Inc. Client: Project: Greater DJ Watering Gathering Gobbler Billings, MT Project No: 114-182241 Figure GRAIN SIZE DISTRIBUTION TEST DATA 5/11/2012 Project: Greater DJ Watering Gathering Gobbler Project Number: 114-182241 Location:Tt-7 Depth:9'-10'A Dry Cumulative Cumulative Sample Pan Sieve Weight and Tare Tare Tare Weight Opening Retained Percent Percent (grams) (grams) (grams) Size (grams) Finer Retained 92.47 0.00 0.00 #20 0.00 100.0 0.0 #40 9.39 89.8 10.2 #80 48.88 47.1 52.9 #200 77.09 16.6 83.4 Gravel Sand Fines Cobbles Coarse Fine Total Coarse Medium Fine Total Silt Clay Total 0.0 0.0 0.0 0.0 0.0 10.2 73.2 83.4 16.6 D10 D15 D20 D30 D50 D60 D80 D85 D90 D95 0.0845 0.1172 0.1907 0.2302 0.3350 0.3741 0.4270 0.5181 Fineness Modulus _ 0.89 Tetra Tech, Inc. PERMEABILITY TEST REPORT TEST DATA: SAMPLE DATA: Specimen Height (cm) : 7. 50 Sample Identification : Tt-8 14' -21 ' Specimen Diameter (cm) : 7.07 Dry Unit Weight (pcf) : 122.4 Visual Description : Moisture Before Test (%) : 7.8 Moisture After Test (%) : 0 .0 Remarks: Run Number : 1 • 2 A Cell Pressure (psi ) : 65.0 Maximum Dry Density (pcf) : 128 . 8 Optimum Moisture Content (%) : 8.8 Sat . Pressure (psi ) : 60.0 ASTM(D698) Diff . Head (psi ) : 1 . 1 Percent Compaction : 95. 0% Permeameter type: Flexwall Perm. (cm/sec) : 1.67 x 10--5 Sample type : Remolded TIME - t (sec) 0 2500 5000 7500 10000 0 O r-, 1O 20 O 30 . li 40 50 1 x 10--4 U 1 x 10--5 J - Q 2 1 x 10^-6 10 15 20 25 30 AVERAGE HYDRAULIC GRADIENT - dH/L (cm/cm) Project : Greater DJ Water Gathering Gobbler Project No . : 114-182241 Location : File No . : 239 Date : 5/11/2012 Lab No . : Tested by : PERMEABILITY TEST REPORT Checked by : TETRA TECH Test : FH - Fa l I i ng head C / i o i I 0 2 4 6 8 10 12 Normal Stress, ksf 6 I Sample No. 1 2 3 Water Content, ')/0 8.8 8.8 8.8 5 Dry Density, pcf 122.4 122.4 122.4 Tu.. Saturation, % 63.0 63.0 63.0 cn 4 Void Ratio 0.3770 0.3770 0.3770 cn 3 Diameter, in. 2.50 2.50 2.50 a I Height, in. 1.00 1.00 1.00 A3 i i Water Content, % 9.4 8.6 7.4 '6 i Dry Density, pcf 123.1 123.2 123.5 2 - 2 0 Saturation, % 68.4 63.1 54.9 Q Void Ratio 0.3696 0.3682 0.3647 Diameter, in. 2.50 2.50 2.50 1 1/.-- - Height, in. 0.99 0.99 0.99 Normal Stress, ksf 1.00 2.00 5.00 o Fail. Stress, ksf 1.51 2.06 3.66 0 1 2 3 4 Strain, % 1.2 1.2 3.2 Strain, % Ult. Stress, ksf Strain, % Strain rate, in./min. 0.01 0.01 0.01 Sample Type: Remolded Client: Description: Project: Greater DJ Watering Gathering Gobbler Assumed Specific Gravity=2.70 Source of Sample: Tt-8 Depth: 14'-21' Remarks: Proj. No.: 114-182241 Date Sampled: DIRECT SHEAR TEST REPORT Tetra Tech, Inc. Figure Billings, MT 6 Results C, ksf 0.98 (I), deg 28 _ Tan( ) 0.54 4 - En I v; cn (175 2 0 III lilt II II 0 2 4 6 8 10 12 Normal Stress, ksf 6 I Sample No. 1 2 3 Water Content, % 8.8 8.8 8.8 5 Dry Density, pcf 122.4 122.4 122.4 I m Saturation, % 63.0 63.0 63.0 4 I I c Void Ratio 0.3770 0.3770 0.3770 y . 3 Diameter, in. 2.50 2.50 2.50 a I Height, in. 1.00 1.00 1.00 in 3 Water Content, % 9.4 8.6 7.4 Dry Density, pcf 123.1 123.2 123.5 cr) 2 2 0 Saturation, % 68.4 63.1 54.9 1 Q Void Ratio 0.3696 0.3682 0.3647 Diameter, in. 2.50 2.50 2.50 1 I Height, in. 0.99 0.99 0.99 Normal Stress, ksf 1.00 2.00 5.00 0 I Fail. Stress, ksf 1.51 2.06 3.66 0 1 2 3 4 Strain, % 1.2 1.2 3.2 Strain, % Ult. Stress, ksf Strain, % Strain rate, in./min. 0.01 0.01 0.01 Sample Type: Remolded Client: Description: Project: Greater DJ Watering Gathering Gobbler Assumed Specific Gravity= 2.70 Source of Sample: Tt-8 Depth: 14'-21' Remarks: Proj. No.: 114-182241 Date Sampled: DIRECT SHEAR TEST REPORT Tetra Tech, Inc. Figure Billings, MT PERMEABILITY TEST REPORT TEST DATA: SAMPLE DATA: Specimen Height (cm) : 7. 50 Sample Identification : Tt-5 & Tt-7 0-7' Specimen Diameter (cm) : 7.07 Dry Unit Weight (pcf) : 113 .4 Visual Description : Moisture Before Test (%) : 9 .3 Moisture After Test (%) : 0.0 Remarks: Run Number : 1 • 2 • Cell Pressure (psi ) : 65.0 Maximum Dry Density (pcf) : 119 .4 Optimum Moisture Content (%) : 10. 3 Sat . Pressure (psi ) : 60.0 ASTM(D698) Diff . Head (psi ) : 1 .0 Percent Compaction : Permeameter type: Flexwall Perm. (cm/sec) : 2.06 x 10^-4 Sample type: Remolded TIME - t (sec) 0 250 500 750 1000 0 O 1O U > 20 w J O 30 O J 40 50 - U• 1 x 10^-3 8 x 10^-4 E 6 x 10^-4 4 x 10^-4 H J • • 2 x 10^-4 gAtikor 1 x 10^-4 0 5 10 15 20 AVERAGE HYDRAULIC GRADIENT - dH/L (cm/cm) Project : Greater DJ Water Gathering Gobbler Project No . : 114-182241 Location : File No . : 238 Date: 5/10/2012 Lab No . : Tested by : PERMEABILITY TEST REPORT Checked by : TETRA TECH Test : FH - Fa l I i ng head C i 0 0 2 4 6 8 10 12 Normal Stress, ksf 6 I I i Sample No. 1 2 3 Water Content, % 10.3 10.3 10.3 5 I Dry Density, pcf 113.5 113.5 113.5 A. Saturation, % 57.3 57.3 57.3 4 I 3 Void Ratio 0.4852 0.4852 0.4852 e Diameter, in. 2.50 2.50 2.50 m Height, in. 1.00 1.00 1.00 cn 3 Water Content, % 15.8 14.3 12.0 L a Dry Density, pcf 114.5 114.5 114.6 2 — Saturation, % 90.3 81.9 68.8 2 Q Void Ratio 0.4723 0.4720 0.4708 1 Diameter, in. 2.50 2.50 2.50 1 Height, in. 0.99 0.99 0.99 Normal Stress, ksf 1.00 2.00 5.00 0 /I I I Fail. Stress, ksf 1.12 1.76 3.90 0 1.5 3 4.5 6 Strain, % 1.6 3.2 4.0 Strain, % Ult. Stress, ksf Strain, % Strain rate, in./min. 0.01 0.01 0.01 Sample Type: Remolded Client: Description: Project: Greater DJ Watering Gathering Gobbler Assumed Specific Gravity= 2.70 Source of Sample: Tt-5&Tt-7 Depth: 0-7' Remarks: Proj. No.: 114-182241 Date Sampled: DIRECT SHEAR TEST REPORT Tetra Tech, Inc. Figure Billings, MT GRAIN SIZE DISTRIBUTION CLIENT Anadarko PROJECT NAME Greater DJ Water Gathering(Gobbler Site) PROJECT NUMBER 114-182241 PROJECT LOCATION Weld County,CO U.S.SIEVE OPENING IN INCHES U.S.SIEVE NUMBERS HYDROMETER 6 4 3 2 1.5 1 1/23/8 3 4 6 810 1416 20 30 40 50 60 100 140 200 100 I I I I III I I I 95 • 90 85 80 75 70 H 65 x O 60 w >- 55 W 50 z LL H 45 Z W m 40 W a 35 • 30 25 20 15 10 5 0 100 10 1 0.1 0.01 0.001 GRAIN SIZE IN MILLIMETERS COBBLES GRAVEL SAND SILT OR CLAY coarse fine coarse medium fine ID Depth (ft) Classification LL PL PI Cc Cu • Bulk(0-7 ft) 0.0 SILTY, CLAYEY SAND(SC-SM) 21 15 6 ID Depth (ft) D100 D60 D30 D10 %Gravel %Sand %Silt %Clay • Bulk(0-7 ft) 0.0 19 0.299 8.4 59.6 32.1 GRAIN SIZE DISTRIBUTION CLIENT Anadarko PROJECT NAME Greater DJ Water Gathering(Gobbler Site) PROJECT NUMBER 114-182241 PROJECT LOCATION Weld County,CO U.S.SIEVE OPENING IN INCHES U.S.SIEVE NUMBERS HYDROMETER 6 4 3 2 1.5 1 1/23/8 3 4 6 810 1416 20 30 40 50 60 100 140 200 100 I I 1 ill III I I I 95 90 85 80 75 70 H 65 x O 60 w • >- 55 W 50 z LL H 45 Z W m 40 W a 35 - 30 25 20 15 10 5 0 100 10 1 0.1 0.01 0.001 GRAIN SIZE IN MILLIMETERS COBBLES GRAVEL SAND SILT OR CLAY coarse fine coarse medium fine ID Depth (ft) Classification LL PL PI Cc Cu • Bulk(14-21 ft) 14.0 SILTY, CLAYEY SAND(SC-SM) 22 16 6 ID Depth (ft) D100 D60 D30 D10 %Gravel %Sand %Silt %Clay • Bulk(14-21 ft) 14.0 19 0.457 3.7 59.0 37.4 GRAIN SIZE DISTRIBUTION CLIENT Anadarko PROJECT NAME Greater DJ Water Gathering(Gobbler Site) PROJECT NUMBER 114-182241 PROJECT LOCATION Weld County,CO U.S.SIEVE OPENING IN INCHES U.S.SIEVE NUMBERS HYDROMETER 6 4 3 2 1.5 1 1/23/8 3 4 6 810 1416 20 30 40 50 60 100 140 200 100 I I I I I III I I I 95 90 85 80 75 70 65 O 60 >- 55 • 50 LL H 45 W m 40 W a 35 30 25 20 15 10 5 0 100 10 1 0.1 0.01 0.001 GRAIN SIZE IN MILLIMETERS COBBLES GRAVEL SAND SILT OR CLAY coarse fine coarse medium fine ID Depth (ft) Classification LL PL PI Cc Cu • Tt-5 9.0 SANDY LEAN CLAY(CL) 35 18 17 X Tt-5 19.0 ID Depth (ft) D100 D60 D30 D10 %Gravel %Sand %Silt %Clay • Tt-5 9.0 19 0.111 7.0 37.8 55.2 X Tt-5 19.0 19 1.28 0.181 9.0 68.2 22.8 GRAIN SIZE DISTRIBUTION CLIENT Anadarko PROJECT NAME Greater DJ Water Gathering(Gobbler Site) PROJECT NUMBER 114-182241 PROJECT LOCATION Weld County,CO U.S.SIEVE OPENING IN INCHES I U.S.SIEVE NUMBERS I HYDROMETER 6 4 3 2 1.5 1 1/2 3 4 6 810 1416 20 30 40 50 60 100 140 200 100 -1N-.. i 95 90 85 80 • 75 70 65 H x • 60 w m 55 m m w 50 z LL H 45 • z W 40 ce a 35 30 25 EQ 20 15 10 5 0 100 10 1 0.1 0.01 0.001 GRAIN SIZE IN MILLIMETERS COBBLES GRAVEL SAND SILT OR CLAY coarse fine coarse medium fine ID Depth (ft) Classification LL PL PI Cc Cu • Tt-6 4.0 SANDY LEAN CLAY(CL) 36 24 12 X Tt-6 9.0 SILTY,CLAYEY SAND with GRAVEL(SC-SN) 22 15 7 • Tt-6 19.0 FAT CLAY(CH) 60 27 33 ID Depth (ft) D100 D60 D30 D10 %Gravel %Sand %Silt %Clay • Tt-6 4.0 9.5 0.082 1.7 39.1 59.3 X Tt-6 9.0 19 1.318 0.158 23.6 52.3 24.2 • Tt-6 19.0 0.075 95.9 GRAIN SIZE DISTRIBUTION CLIENT Anadarko PROJECT NAME Greater DJ Water Gathering(Gobbler Site) PROJECT NUMBER 114-182241 PROJECT LOCATION Weld County,CO U.S.SIEVE OPENING IN INCHES U.S.SIEVE NUMBERS HYDROMETER 6 4 3 2 1.5 1 3/4 1/23/8 3 4 6 810 1416 30 40 50 60 100 140 200 100 I I III II II I I I 95 • I 90 85 80 75 70 H 65 x O 60 w >- 55 W 50 z LL H 45 W m 40 W a 35 30 25 20 15 10 5 0 100 10 1 0.1 0.01 0.001 GRAIN SIZE IN MILLIMETERS COBBLES GRAVEL SAND SILT OR CLAY coarse fine coarse medium fine ID Depth (ft) Classification LL PL PI Cc Cu • Tt-7 9.0 X Tt-7 19.0 FAT CLAY(CH) 58 22 36 ID Depth (ft) D100 D60 D30 D10 %Gravel %Sand %Silt %Clay • Tt-7 9.0 0.841 0.262 0.119 0.0 83.4 16.6 X Tt-7 19.0 0.075 92.6 GRAIN SIZE DISTRIBUTION CLIENT Anadarko PROJECT NAME Greater DJ Water Gathering(Gobbler Site) PROJECT NUMBER 114-182241 PROJECT LOCATION Weld County,CO U.S.SIEVE OPENING IN INCHES U.S.SIEVE NUMBERS HYDROMETER 6 4 3 2 t5 1 3/4 1/2 3 6 81,2 14 6 20 30 40 50 60 100140200 100 I I I I I I 95 • • 90 • 85 80 • 75 • 70 65 O 60 w m 55 50 LL H 45 ° 40 W a 35 • 30 25 20 15 10 5 0 100 10 1 0.1 0.01 0.001 GRAIN SIZE IN MILLIMETERS COBBLES GRAVEL SAND SILT OR CLAY coarse fine coarse medium fine ID Depth (ft) Classification LL PL PI Cc Cu • Tt-8 2.0 SILTY, CLAYEY SAND(SC-SM) 24 18 6 X Tt-8 9.0 LEAN CLAY with SAND(CL) 32 17 15 ♦ Tt-8 39.0 FAT CLAY(CH) 62 25 37 ID Depth (ft) D100 D60 D30 D10 %Gravel %Sand %Silt %Clay • Tt-8 2.0 2 0.2 0.0 69.7 30.3 X Tt-8 9.0 9.5 0.2 22.8 77.0 ♦ Tt-8 39.0 0.075 92.8 Tetra Tech MM MOISTURE-DENSITY RELATIONSHIP 350 Indiana Street,Suite 500 Golden,CO-80401 Telephone: 303-217-5700 Fax: 303-217-5705 CLIENT Anadarko PROJECT NAME Greater DJ Water Gathering(Gobbler Site) PROJECT NUMBER 114-182241 PROJECT LOCATION Weld County,CO 135 130 125 Source of Material Bulk(0-7 ft)0.0 Description of Material SILTY,CLAYEY SAND(SC-SM) 120 Test Method ASTM D698 Method A 115 TEST RESULTS Maximum Dry Density 119.4 PCF 110 Optimum Water Content 10.3 O 0 ATTERBERG LIMITS w 105 0 >- LL PL PI a 21 15 6 100 Curves of 100% Saturation for Specific Gravity Equal to: 2.80 95 \ 2.70 2.60 F- 90 ❑ (/) 7 F 85 0_ a CD s w 0 0 80 0 0 75 0 5 10 15 20 25 30 35 40 45 a 2 WATER CONTENT,% Tetra Tech MM MOISTURE-DENSITY RELATIONSHIP 350 Indiana Street,Suite 500 Golden,CO-80401 Telephone: 303-217-5700 Fax: 303-217-5705 CLIENT Anadarko PROJECT NAME Greater DJ Water Gathering(Gobbler Site) PROJECT NUMBER 114-182241 PROJECT LOCATION Weld County,CO 135 130 • 125 Source of Material Bulk(14-21 ft) 14.0 Description of Material SILTY,CLAYEY SAND(SC-SM) 120 Test Method ASTM D698 Method A 115 TEST RESULTS Maximum Dry Density 128.7 PCF 110 Optimum Water Content 9.0 O 0 ATTERBERG LIMITS w 105 0 >- LL PL PI a 22 16 6 100 Curves of 100% Saturation for Specific Gravity Equal to: 2.80 95 \ 2.70 2.60 F- 90 ❑ (/) 7 F 85 0_ a CD s w 0 0 80 0 0 75 0 5 10 15 20 25 30 35 40 45 a 2 WATER CONTENT,% One-Dimensional Consolidation Testing Embankment Material @ from 0-7' -1.0 0.0 1.0 c R 2.0 R V d J 3.0 4.0 5.0 10 100 1,000 10,000 100,000 Effective Vertical Stress (psf) Consol BuIkTT-5 and TT-7, 0-7ft.xls One-Dimensional Consolidation Testing Embankment Material @ from 14-21' -1.0 0.0 1.0 2.0 c R N 3.0 m V d > 4.0 5.0 6.0 7.0 10 100 1,000 10,000 100,000 Effective Vertical Stress (psf) Consol BuIkTT-8, 14-21 ft.xls ATTACHMENT C SEEP/VV AND SLOPE/VV RESULT FIGURES Tetra Tech July 12, 2012 Greater DJ Water Gathering Pit Embankments - Gobbler Site Anadarko Petroleum Corporation Name:Embankment Sandy Clay Model:Saturated/Unsaturated Vol.WC.Function:Embankment Sandy Clay Seepage Modeling - Full Water Height Created B : He er Lance Name:Sandy Clay Y Y Model:Saturated/Unsaturated Date: 6/25/2012 Vol.WC.Function:Sandy Clay Method: Method: Steady-State Name:Lean Clay Model:Saturated/Unsaturated Vol.WC.Function:Lean Clay Name:Sandy Gravel Model:Saturated!Unsaturated Vol.WC.Function:Sandy Gravel V N co 5.16 Name:Claystone Bedrock co Model:Saturated/Unsaturated c Vol.WC.Function:Claystone Bedrock ,o d, _ ,0 5.15 O r 5.14 . 5.13 C O - Rf 5.1 2 N W 5.11 • 5.10 I I 0 50 100 150 200 Distance (ft) Project No: 114-182241 June, 2012 U Seepage Analysis - Embankments Greater DJ Water Gathering, Gobbler Site Weld County, Colorado Greater DJ Water Gathering Pit Embankments - Gobbler Site Anadarko Petroleum Corporation Name:Embankment Sandy Clay Model:Saturated/Unsaturated Vol.WC.Function:Embankment Sandy Clay Seepage Modeling - Freeboard Water Height Created B : He er Lance Name:Sandy Clay Y Y Model:Saturated/Unsaturated Date: 6/25/2012 Vol.WC.Function:Sandy Clay Method: Method: Steady-State Name:Lean Clay Model:Saturated/Unsaturated Vol.WC.Function:Lean Clay Name:Sandy Gravel Model:Saturated!Unsaturated Vol.WC.Function:Sandy Gravel m Co Name:Claystone Bedrock 5.16 o Model:Saturated/Unsaturated Vol.WC.Function:Claystone Bedrock CO M 5.15 .• -. o O . - - d b b a b--c--•s, O O r 5.14 5.13 c a{ 5.12 N 5.11 • 5.10 0 50 100 150 200 Distance (ft) Project No: 114-182241 June, 2012 U Seepage Analysis - Embankments Greater DJ Water Gathering, Gobbler Site Weld County, Colorado Greater DJ Water Gathering Pit Embankments - Gobbler Site Name:Embankment Sandy Clay Unit Weight:126 pcf Anadarko Petroleum Corporation Cohesion:75 psf End of Construction - Static (Downstream) Phi:20° Created By: Heyer, Lance Name:SandyClay Date: 6/25/2012 Unit Weight:115 pd Cohesion:50 psf Method: Spencer Phi:25° Material Model: Model: Mohr-Coulomb ■ Name:Lean Clay Horizontal Seismic Coefficient: 0 Unit Weight:105 pcf Cohesion:100 psf Phi:25° ■ Name:Sandy Gravel Unit Weight:125 pcf Cohesion:0 psf Phi:28° 5.16 2.7 I ■ Name:Claystone Bedrock .1 Unit Weight:135 pcf Illlllll�lllllllllllllllllll`Illhlp... Cohesion:200 psf 5.15 O Phi:24° O al c> r 5.14 it 5.13 ' c O 5.12 I _N W 5.11 5.10 Il 0 50 100 150 200 Distance (ft) Project No: 114-182241 June, 2012 U Slope Stability Analysis - Embankments Greater DJ Water Gathering, Gobbler Site Weld County, Colorado Greater DJ Water Gathering Pit Embankments - Gobbler Site Name:Embankment Sandy Clay Unit Weight:126 pcf Anadarko Petroleum Corporation Cohesion:75 psf End of Construction - Pseudostatic (Downstream) Pn.2o° Created By: Heyer, Lance Name:SandyClay Date: 6/25/2012 Unit Weight:115 pd Cohesion:50 psf Method: Spencer Phi:25° Material Model: Model: Mohr-Coulomb ■ Name:Lean Clay Horizontal Seismic Coefficient: 0.05 Unit Weight:105 pcf Cohesion:100 psf Phi:25° ■ Name:Sandy Gravel Unit Weight:125 pcf Cohesion:0 psf Phi:28° 5.16 2.3 ■ Name:Claystone Bedrock Unit Weight:135 psf 5.15 Cohesion:200 psf O - — IIIIIhq,• Phi:24° O r 5.14 X 5.13 c O 5.12 N W 5.11 5.10 0 50 100 150 200 Distance (ft) Project No: 114-182241 June, 2012 U Slope Stability Analysis - Embankments Greater DJ Water Gathering, Gobbler Site Weld County, Colorado Greater DJ Water Gathering Pit Embankments - Gobbler Site Name:Embankment Sandy Clay Unit Weight:126 pcf Anadarko Petroleum Corporation Cohesion:75 psf End of Construction - Static (Upstream) Pn.2o° Created By: Heyer, Lance Name:SandyClay Date: 6/25/2012 Unit Weight:115 pd Cohesion:50 psf Method: Spencer Phi:25° Material Model: Model: Mohr-Coulomb ■ Name:Lean Clay Horizontal Seismic Coefficient: 0 Unit Weight:105 pcf Cohesion:100 psf Phi:25° ■ Name:Sandy Gravel Unit Weight:125 pcf Cohesion:0 psf Phi:28° 5.16 2,2 fIC ■ Name:Claystone Bedrock Pr Unit Weight:135 psf 5.15 - Cohesion:200 psf Phi:24° r 5.14 X 5.13 c O 5.12 N W 5.11 5.10 0 50 100 150 200 Distance (ft) Project No: 114-182241 June, 2012 U Slope Stability Analysis - Embankments Greater DJ Water Gathering, Gobbler Site Weld County, Colorado Greater DJ Water Gathering Pit Embankments - Gobbler Site Name:Embankment Sandy Clay Unit Weight:126 pcf Anadarko Petroleum Corporation Cohesion:75 psf End of Construction - Pseudostatic (Upstream) Phi:20° Created By: Heyer, Lance Name:SandyClay Date: 6/25/2012 Unit Weight:115 pd Cohesion:50 psf Method: Spencer Phi:25° Material Model: Model: Mohr-Coulomb ■ Name:Lean Clay Horizontal Seismic Coefficient: 0.05 Unit Weight:105 pcf Cohesion:100 psf Phi:25° ■ Name:Sandy Gravel Unit Weight:125 pcf Cohesion:0 psf Phi:28° 5.16 1.9 • Name:Claystone Bedrock Unit Weight:135 psf Cohesion:200 psf 5.15 - Phi:24° O o .,duly r 5.14 X it 5.13 c O 5.12 _N W 5.11 5.10 0 50 100 150 200 Distance (ft) Project No: 114-182241 June, 2012 U Slope Stability Analysis - Embankments Greater DJ Water Gathering, Gobbler Site Weld County, Colorado Greater DJ Water Gathering Pit Embankments - Gobbler Site Name:Embankment Sandy Clay Unit Weight:126 pcf Anadarko Petroleum Corporation Cohesion:75 psf Full Water Height- Static (Downstream) Pn.2o° Created By: Heyer, Lance Name:SandyClay Date: 6/25/2012 Unit Weight:115 pd Cohesion:50 psf Method: Spencer Phi:25° Material Model: Model: Mohr-Coulomb ■ Name:Lean Clay Horizontal Seismic Coefficient: 0 Unit Weight:105 pcf Cohesion:100 psf Phi:25° ■ Name:Sandy Gravel Unit Weight:125 pcf Cohesion:0 psf Phi:28° 5.16 1.6 ■ Name:Claystone Bedrock Unit Weight:135 pcf 5.15 — Cohesion:200 psf 24° O r 5.14 X it 5.13 c O 5.12 N W 5.11 5.10 0 50 100 150 200 Distance (ft) Project No: 114-182241 June, 2012 U Slope Stability Analysis - Embankments Greater DJ Water Gathering, Gobbler Site Weld County, Colorado Greater DJ Water Gathering Pit Embankments - Gobbler Site Name:Embankment Sandy Clay Unit Weight:126 pcf Anadarko Petroleum Corporation Cohesion:75 psf Freeboard Water Height- Pseudostatic (Downstream) Phi 20° Created By: Heyer, Lance Name:SandyClay Date: 6/25/2012 Unit Weight:115 pd Cohesion:50 psf Method: Spencer Phi:25° Material Model: Model: Mohr-Coulomb ■ Name:Lean Clay Horizontal Seismic Coefficient: 0.05 Unit Weight:105 pcf Cohesion:100 psf Phi:25° ■ Name:Sandy Gravel Unit Weight:125 pcf Cohesion:0 psf Phi:28° 5.16 1.5 ■ Name:Claystone Bedrock Unit Weight:135 pcf 5.15 — ______Dili Cohesion:200 psf Phi:24° O MEIr 5.14 X it 5.13 c O 5.12 N W 5.11 5.10 0 50 100 150 200 Distance (ft) Project No: 114-182241 June, 2012 U Slope Stability Analysis - Embankments Greater DJ Water Gathering, Gobbler Site Weld County, Colorado Greater DJ Water Gathering Pit Embankments - Gobbler Site Name:Embankment Sandy Clay Unit Weight:126 pcf Anadarko Petroleum Corporation Cohesion:75 psf Freeboard Water Height- Static (Upstream) Phi 20° Created By: Heyer, Lance Name:SandyClay Date: 6/25/2012 Unit Weight:115 pd Cohesion:50 psf Method: Spencer Phi:25° Material Model: Model: Mohr-Coulomb ■ Name:Lean Clay Horizontal Seismic Coefficient: 0 Unit Weight:105 pcf Cohesion:100 psf Phi:25° ■ Name:Sandy Gravel Unit Weight:125 pcf Cohesion:0 psf Phi:28° 5.16 2.2 fIC ■ Name:Claystone Bedrock pr Unit Weight:135 pcf 5.15 - Cohesion:200 psf Phi:24° O mills MEI r 5.14 X it 5.13 c O 5.12 N_ 0 5.11 5.10 0 50 100 150 200 Distance (ft) Project No: 114-182241 June, 2012 U Slope Stability Analysis - Embankments Greater DJ Water Gathering, Gobbler Site Weld County, Colorado Greater DJ Water Gathering Pit Embankments - Gobbler Site Name:Embankment Sandy Clay Unit Weight:126 pcf Anadarko Petroleum Corporation Cohesion:75 psf Freeboard Water Height- Pseudostatic (Upstream) Phi 20° Created By: Heyer, Lance Name:SandyClay Date: 6/25/2012 Unit Weight:115 pd Cohesion:50 psf Method: Spencer Phi:25° Material Model: Model: Mohr-Coulomb ■ Name:Lean Clay Horizontal Seismic Coefficient: 0.05 Unit Weight:105 pcf Cohesion:100 psf Phi:25° ■ Name:Sandy Gravel Unit Weight:125 pcf Cohesion:0 psf Phi:28° 5.16 1.7 ■ Name:Claystone Bedrock Unit Weight:135 pcf 5.15 `+ 'l10i Ph Cohesion:200 psf —MEP r 5.14 'ulIIMEI 5.13 ' c O 5.12 N_ 0 5.11 5.10 0 50 100 150 200 Distance (ft) Project No: 114-182241 June, 2012 U Slope Stability Analysis - Embankments Greater DJ Water Gathering, Gobbler Site Weld County, Colorado Greater DJ Water Gathering Pit Embankments - Gobbler Site Name:Embankment Sandy Clay Unit Weight:126 pcf Anadarko Petroleum Corporation Cohesion:75 psf Full Water Height- Static (Downstream) Pn.2o° Created By: Heyer, Lance Name:SandyClay Date: 6/25/2012 Unit Weight:115 pd Cohesion:50 psf Method: Spencer Phi:25° Material Model: Model: Mohr-Coulomb ■ Name:Lean Clay Horizontal Seismic Coefficient: 0 Unit Weight:105 pcf Cohesion:100 psf Phi:25° ■ Name:Sandy Gravel Unit Weight:125 pcf Cohesion:0 psf Phi:28° 5.16 1.6 ■ Name:Claystone Bedrock Unit Weight:135 pcf 5.15 — Cohesion:200 psf 24° O r 5.14 X it 5.13 c O 5.12 N W 5.11 5.10 0 50 100 150 200 Distance (ft) Project No: 114-182241 June, 2012 U Slope Stability Analysis - Embankments Greater DJ Water Gathering, Gobbler Site Weld County, Colorado Greater DJ Water Gathering Pit Embankments - Gobbler Site Name:Embankment Sandy Clay Unit Weight:126 pcf Anadarko Petroleum Corporation Cohesion:75 psf Full Water Height - Pseudostatic (Downstream) Phi 20° Created By: Heyer, Lance Name:SandyClay Date: 6/25/2012 Unit Weight:115 pd Cohesion:50 psf Method: Spencer Phi:25° Material Model: Model: Mohr-Coulomb ■ Name:Lean Clay Horizontal Seismic Coefficient: 0.05 Unit Weight:105 pcf Cohesion:100 psf Phi:25° ■ Name:Sandy Gravel Unit Weight:125 pcf Cohesion:0 psf Phi:28° 5.16 1.3 ■ Name:Claystone Bedrock Unit Weight:135 psf 5.15 — Cohesion:200 psf 24° O r 5.14 X it 5.13 c O 5.12 N W 5.11 5.10 0 50 100 150 200 Distance (ft) Project No: 114-182241 June, 2012 U Slope Stability Analysis - Embankments Greater DJ Water Gathering, Gobbler Site Weld County, Colorado Greater DJ Water Gathering Pit Embankments - Gobbler Site Name:Embankment Sandy Clay Unit Weight:126 pcf Anadarko Petroleum Corporation Cohesion:75 psf Full Water Height- Static (Upstream) Phi:20° Created By: Heyer, Lance Name:SandyClay Date: 6/25/2012 Unit Weight:115 pd Cohesion:50 psf Method: Spencer Phi:25° Material Model: Model: Mohr-Coulomb ■ Name:Lean Clay Horizontal Seismic Coefficient: 0 Unit Weight:105 pcf Cohesion:100 psf Phi:25° ■ Name:Sandy Gravel Unit Weight:125 pcf Cohesion:0 psf Phi:28° 5.16 2.4 • Name: soc k Unit W eight:Clay 135tone pcfBedr �--. 5.15 - Cohesion:200 psf Phi:24° o nlil0lN r 5.14 X it 5.13 c O 5.12 N_ 0 5.11 5.10 0 50 100 150 200 Distance (ft) Project No: 114-182241 June, 2012 U Slope Stability Analysis - Embankments Greater DJ Water Gathering, Gobbler Site Weld County, Colorado Greater DJ Water Gathering Pit Embankments - Gobbler Site Name:Embankment Sandy Clay Unit Weight:126 pcf Anadarko Petroleum Corporation Cohesion:75 psf Full Water Height - Pseudostatic (Upstream) Phi:20° Created By: Heyer, Lance Name:SandyClay Date: 6/25/2012 Unit Weight:115 pd Cohesion:50 psf Method: Spencer Phi:25° Material Model: Model: Mohr-Coulomb ■ Name:Lean Clay Horizontal Seismic Coefficient: 0.05 Unit Weight:105 pcf Cohesion:100 psf Phi:25° ■ Name:Sandy Gravel Unit Weight:125 pcf Cohesion:0 psf Phi:28° 5.16 1.8 • Name:Claystone Bedrock Unit Weight:135 pcf �--. 5.15 - 1 Cohesion:200 psf Phi:24° O O nll�� r 5.14 X it 5.13 c O 5.12 _N W 5.11 5.10 0 50 100 150 200 Distance (ft) Project No: 114-182241 June, 2012 U Slope Stability Analysis - Embankments Greater DJ Water Gathering, Gobbler Site Weld County, Colorado Greater DJ Water Gathering Pit Embankments - Gobbler Site Name:Embankment Sandy Clay Unit Weight:126 pcf Anadarko Petroleum Corporation Cohesion:75 psf Full Water Height - Rapid Draw Down Phi:20° Created By: Heyer, Lance Name:SandyClay Date: 6/25/2012 Unit Weight:115 pd Cohesion:50 psf Method: Spencer Phi:25° Material Model: Model: Mohr-Coulomb ■ Name:Lean Clay Horizontal Seismic Coefficient: 0 Unit Weight:105 pcf Cohesion:100 psf Phi:25° ■ Name:Sandy Gravel Unit Weight:125 pcf Cohesion:0 psf Phi:28° 5.16 1.9 ■ Name:Claystone Bedrock i �J Unit Weight:135 pcf �"�"�" Cohesion:200 psf 0 5.15 — Phi:24° 0 O r 5.14 X it 5.13 C O 5.12 _N W 5.11 5.10 0 50 100 150 200 Distance (ft) Project No: 114-182241 June, 2012 U Slope Stability Analysis - Embankments Greater DJ Water Gathering, Gobbler Site Weld County, Colorado Hello