LSAR 9 II B explor_rept_REV_0508.pdf

Los Angeles District Geotechnical Branch

Field investigation of foundations for sheet-pile, roadway “levee”, and river-channel realignments Lower Santa Ana River Project, Reach “9 II B” Orange and Riverside Counties, CA

Left, Project area looking upstream (east) 8 April 2008. Visible are Santa Ana River, the CalTrans bike path (lower right of frame), the 91 Freeway (right center of frame). The Green River Golf Club is below the tall trees in the left center of frame.

Refer to fig.1 in the report for more on these locations.

by US Army Corps of Engineers

Geotechnical Branch, Geology and Investigations Section 915 Wilshire Blvd., 13th floor, Los Angeles, CA 90017

POC: ph. (213) 452-3585 mark.chatman@usace.army.mil

2 May 2008

Background. Geotechnical field investigations (drilling, borehole logging and sampling of soils, laboratory testing of soil samples) was requested of the US Army Corps of Engineers Geotechnical Branch, Geology & Investigations Section, Los Angeles (hereafter, “Geotech”) at the end of January 2008 for the segment of Lower Santa Ana River Reach 9 planned improvements that has come to be known as “Reach 9 II B” (as shown on fig. 1). The first actions that were taken were that the US Army Corps of Engineers Geotechnical Branch, Soils Design & Materials Section, Los Angeles, at the beginning of February 2008 conducted a search of archived Corps of Engineers data from previous drilling projects along the river and requested of CalTrans that they also search for logs they generated during the construction of the 91 Freeway, which adjoins this project for a linear distance of about 6,000 ft. The Corps files contained one log (TH87- 6, as shown on fig. 1) that was pertinent to this project. No usable, pertinent logs could be supplied by CalTrans. Subsequently, in early March 2008, Geotech and the Soils Design & Materials Section consulted and selected new boring locations for this investigation (fig. 1) and decided upon the testing regime. The borings have been drilled.

The findings of this investigation and methods employed are the subject of the report that follows.

The work. The borings were made with a CME 75 model drill rig equipped with hollow-stem auger drilling tools (see fig. 2). The rig was owned and operated by J.E.T.

Drilling, Inc., of Signal Hill, CA. The work was awarded to J.E.T. via an existing modification to a contract for work on and around the general Prado Dam area. This was contract number W912PL-07-P-0028, modification P0001, issued in 30 Sept. 2007.

How the work tasks were accomplished. A geologist from Geotech took care of locating the holes in the field, coordinating and scheduling access with the Green River Golf Club (for the three golf course holes) and with the Orange County Flood Control District; initiated the underground utility clearances tickets for the borings and verified that all were free of underground utility conflicts as per the locator personnel for the various utility providers; directed the field work; logged and sampled the borings; assured that all site cleanup and pavement patching was done to standards; hand delivered the samples to the laboratory for testing. J.E.T. Drilling personnel were responsible for drilling and backfilling the borings. Soils lab technicians affiliated with Geotech tested the samples. Right-of-entry approvals were in place long prior to planning any of this field exploration, but during the coordinating and scheduling of the work in late March 2008, the Orange County Flood Control District added the requirement that the Corps obtain an encroachment permits. After discussion, Orange County personnel took care of initiating the application and securing the permit for the Corps of Engineers, ultimately waiving the requirement of a permit.

Land ownership and access. The project land is in split ownership. A small parcel in the river bed and on the banks west of Green River Rd. bridge over the Santa Ana River is private land and was pointedly avoided. Land east of and including the Green River Rd. crossing of the Santa Ana River is in Riverside County (see fig. 1), is reportedly

TH08-03

Green River Rd.

boring B1

TH87-6

boring B4

91 freeway TH98-6

OCSD dirt access road

Green River Golf Club

CalTrans bike path 91 freeway

NORTH

Santa Ana River

91 freeway

Fig. 1.—The project area (yellow, dotted outline), showing the locations of completed borings TH08-01, -02, and -03 (marked in green). Older borings, from previous work, are shown as white circles. Corps of Engineers boring TH87-6 was fortuitously located and of sufficient depth to eliminate the need for “sheet-pile depth” drilling at the eastern edge of this project, and thus one drill hole was eliminated because the TH87-6 data are available. Corps of Engineers test hole TH98-6 is too shallow for project objectives (sheet-pile placement), but is included in this report for information on higher-elevations subsurface materials. CalTrans penetrometer borings B4 and B1 are too distant and too shallow to meet project sheet pile information needs (17 and 32 ft deep, respectively) and were deemed to be located probably on different materials (in a highway fill, at least in part). Further, they are illegible.

Note: No scale available for fig. 1. For a rough approximation of scale, the Green River Golf Club clubhouse facility, the tan-tile-roofed structure that dominates the south-central part of this photograph, is approximately 175 ft long in the north-to-south direction. The project features (the bright blue lines shown above) are in total, 5,830 ft long, at the maximum.

Fig. 2.—The drilling equipment used (this is boring location TH08-03, looking west-northwest, 8 April 2008 owned by Orange County, and was determined by the golf club management to be part of the golf club. It was accessed for this job under the approval of the golf course management (that includes location for boring no. TH08-01, as shown on fig. 1). The Green River Golf Club to the west of the Green River Rd. crossing of Santa Ana River (see fig. 1) all is in Orange County and owned by the County (figs. 3, 4). The bike path that is between the 91 Freeway to the south and the Santa Ana River to the north (see fig.

5) is owned by CalTrans, while that bike path is maintained and operated by Orange County.

In summary, boring TH08-01 is in Riverside Co., CA, and all the rest are in Orange Co., CA. Two holes are on the golf course, and one hole on a street area controlled by the golf course.

Samples. Samples were tested at the US Army Corps of Engineers Prado Dam Sample Testing Laboratory, located on the Prado Dam facility, in Corona, CA.

From the three borings that were completed, a total of 32 soil samples were collected.

Two of the samples were grab-type, taken from cuttings of the first 5 ft of the borings, but all the rest were drive samples, taken from inside of a SPT-type split spoon sampler.

A total of 11 samples were collected from boring TH08-01; nine from TH08-02, and 12 from TH08-03. Each was subjected to gradation analysis, and all but one were tested for moisture content.

Fig. 3.—Green River Golf Club, Orange Course, looking southeast from near boring location TH08-03, 8 April 2008. See also fig. 1 for an aerial photograph of the Golf Club.

bike path

Santa Ana River

Fig. 4.—One part of the Green River Golf club inside the project area perimeter (between the yellow arrows), looking east-northeast from the bike path on the opposite (south) side of the Santa Ana River, 8 April 2008. River flow is from upper right frame to lower left frame (westward flow) bike path

Santa Ana River

91 Freeway embankment

Fig. 5.—The CalTrans bike path, looking west, 8 April 2008. The 91 Freeway embankment and the Santa Ana River are located at the far left and right-center frame, respectively. River flow is from foreground to the far horizon distance (westward flow).

The logs of borings TH08-01, -02, and -03 are at the back of this report (Attachment 1), as are the logs of one pertinent older Corps of Engineers exploration (TH87-6), and the logs of one other Corps boring in the vicinity (TH98-6).

SPT testing. The standard penetration test was run every 5 ft in these borings, and all but two of the soil samples from this job were taken from the split-spoon sampler used in the standard penetration test.

The drilling and subsurface observations from the field. The drilling was started at 0700 hrs on 7 April, and holes TH08-01 and -02 were completed that day. The water tank on the drill rig (the water is needed to make the drilling mud that, in turn, helps keep the borehole open during drilling) was refilled, a two-hour process, after completing boring TH08-02. The drill was set up at site TH08-03 at the end of the work day on 7 April, so that hole could started early on 8 April. It subsequently was completed by mid-morning on 8 April. Holes were backfilled with cuttings immediately after completion, and a bentonite-chip fill was added at the top to help seal the hole and prevent any caving at the surface. The sod was paced on the very top of hole TH08-02 as it was backfilled (it was drilled on the golf course playing surface). Hole TH08-01, because it was drilled on the pavement of a small turn out area of Green River Rd., was topped with three inches of cold-patch asphalt, immediately after backfilling. There was a small amount of cuttings excess at location TH08-02, which were distributed around a nearby golf course landscaping location. There was no excess drilling mud to be disposed of.

Hole selection. Holes TH08-01 and -03 were located and advanced to depths that show what materials sheet pile would have to be driven through. An older Corps of Engineers boring, TH87-6, was fortuitously located and of sufficient depth (48 ft) that it revealed what sheet pile would encounter at the east end of this job, so no new hole was drilled there and the log of TH87-6 has been included in Attachment 1 of this report. These holes, as well as hole TH08-02, also are indicative of the materials that will have to be excavated for the relocation of Santa Ana River channel northward (in the event that the 91 freeway is expanded by adding additional lanes on the north side of the highway, which would in turn force the river northward and onto the golf course). Further, they are indicative (especially TH08-02) of materials that would be encountered when a temporary construction bypass channel for the Santa Ana River is excavated even farther north into the golf course.

Boring re-numbered. Boring TH08-03 was drilled as number TH08-05, and was re-numbered for the release and publication of the data.

The subsurface. There was consistency in the three holes drilled. Each had a groundwater table at -17 ft to -20 ft below ground surface (the three holes were within a very few vertical feet of each other, at the surface). Each had silty sands from the surface down to near the groundwater table, and each had a coarse sand at the groundwater table and continuing downward, with varying amounts of gravel and cobbles in among the sand at deeper elevations. Bedrock was encountered only in boring, TH08-03, and that was near the bottom of the hole (-43.75 ft below ground surface). That bedrock was a very weakly indurated sand and gravel, which was readily penetrated with the hollow stem auger, although it was difficult to penetrate with the split-spoon sampler. Thus, bedrock problems are not anticipated with the driving of sheet piles in this project. There were very few cohesive soils, and those were very thin, a matter of a few inches in nearly all cases. They were sandwiched in among much coarser sands, gravels, and cobbles.

The sampler was a steel tube with a 1-1/2 inch diameter annulus, and so, cobbles could not be retrieved in samples. Their presence was surmised based on the fluvial environment, the history of the Santa Ana River, drill action, and the knowledge gained from examining other drill logs from along this river.

Heaving sands. Sands at the water table are coarse-grained, angular-grained, and not very dense, so they heave up in the drill stem quite readily. At hole TH08-01, water was used to control these sands, with little success. Later, mud was added to that boring, but once the sands start heaving it is difficult to get them back “under control” and the boring was slow to complete. At subsequent borings, mud was added at ever shallower elevations so as to exert pre-emptive control on the sands (the weight of the dense mud holds these sands down and does not let them rise in the inside the drill stem). The water (or the mud) being added does alter the moisture content of the samples that are collected below the point where water is added. This is particularly so because of the coarse-grained nature of the materials: added water, with or without mud, can readily penetrate them in the downward direction before the drill bit or sampler reaches them. There are a few exceptions, as can be seen in the logs, where non-saturated samples were obtained below the point in the boring where water and mud were added, but such locations are few and most of the moisture content results are of limited to no use due to the added water.

Attachment 1

Logs of borings TH08-01, -02, and -03 (from this job), and logs of older borings from previous work (Corps of Engineers borings

TH87-5, 98-6).

Well-graded sand w/ gravel

Poorly-graded sand w/ gravel

Well-graded sand w/ silt, gravel, cobbles

Poorly-graded sand w/ silt, gravel

Bedrock

Well-graded sand w/ silt, gravel

Poorly-graded sand w/ gravel, cobbles

Silty sand with gravel west entrance to CalTrans bike trail

Bridge over Santa Ana River

Green River Rd.

TH08-01 boring location

Fig. A1-01.—Drill site TH08-01, looking north-northwest on 8 April, 2008. The hole was drilled on the paved area in a small turnout on Green River Road immediately south of the bridge over Santa Ana River that leads north and uphill into the Green River Golf Club.

Boring TH08-02

Santa Ana River

Fig. A1-2.—Drill site TH08-02, looking north, 8 April 2008. The hole was bored into the flat golf course playing surface on the opposite bank of the Santa Ana River from where the photographer is standing. Photo taken from the opposite (south) bank of the Santa Ana River. This is the “Orange Course” of the Green River Golf Club and it was closed for the day by management of the Golf Club, specifically so that we could have unencumbered access to expediently complete this boring. The river flows from the right of this frame to the left (westward flow).

Fig. A1-3.—The drill site of TH08-03, looking northwest, on 8 April 2008. The Green River Golf Club playing surface can be seen on the right half of the frame and the drill site on the left half. The large piles that are visible are of wood chips, made when disposing of tree trimmings. We chose to drill among those piles rather than risk marring the playing surface with the drilling activities.

Attachment 2

Laboratory test data of samples from borings TH08-01, -02, and -

Percent Passing by Weight Gravel (inches) Sand (sieve no.) Fines %W boring-sample# Depth 3 1-1/2 3/4 3/8 4 8 16 30 50 100 200 Classification

TH08-01-1 0-5 100 100 97 84 71 64 53 40 29 21 15.5 8.4 SM-Silty Sand W/Gravel

TH08-01-2 5-6.5 100 100 96 92 84 80 75 65 53 42 31.3 28.6 SM-Silty Sand W/Gravel

TH08-01-3 10-11.5 100 100 100 100 100 98 96 93 88 78 53.8 30.1 ML-Sandy Silt

TH08-01-4 15-16.5 100 100 88 72 58 46 30 16 10 7 4.6 4.9 SP-Poorly Graded Sand W/Gravel

TH08-01-5 20-21.5 100 100 95 90 78 66 46 30 21 15 11.1 12.0

SP-SM Poorly Graded Sand W/Silt and Gravel

TH08-01-6 25-26.5 100 100 84 73 62 50 34 21 15 12 8.8 10.9 SW-SM Well-Graded Sand W Silt and Gravel

TH08-01-7 30-31.5 100 100 86 79 62 49 31 15 8 5 4.0 18.3 SP-Poorly Graded Sand W/Gravel

TH08-01-8 35-36.5 100 100 100 100 100 86 59 30 16 10 7.1 11.0 SW-SM Well-Graded Sand W Silt

TH08-01-9 40-41.5 100 100 93 85 77 68 51 30 18 11 7.4 10.1 SW-SM Well-Graded Sand W Silt and Gravel

TH08-01-10 45-46.5 100 100 87 65 50 40 31 24 19 15 10.4 9.4

GP-GM Poorly Graded Gravel W/Silt and Sand

TH08-01-11 50-51.5 100 100 87 75 54 38 25 18 13 10 7.6 10.7 SW-SM Well-Graded Sand W Silt and Gravel

TH08-02-1 0-1.5 100 100 100 100 100 99 95 80 54 34 23.4 2.7 SM-Silty Sand

TH08-02-2 5-6.5 100 100 100 100 100 100 99 94 47 15 8.2 4.7 SP-SM Poorly Graded Sand W/Silt

TH08-02-3 10-11 100 100 100 100 100 100 100 98 83 40 23.6 9.3 SM-Silty Sand

TH08-02-4 11-11.5 100 100 100 100 100 100 100 100 99 95 62.7 43.6 ML-Sandy Silt

TH08-02-5 15-16.5 100 100 83 72 63 57 46 31 19 12 8.1 7.0

SP-SM Poorly Graded Sand W/Silt and Gravel

TH08-02-6 20-21.5 100 100 93 78 60 45 27 14 7 5 4.4 11.1 SP-Poorly Graded Sand W/Gravel

TH08-02-7 25-26.5 100 100 92 83 69 49 25 13 7 4 3.2 18.3 SW- Well-Graded Sand W Gravel

TH08-02-8 30-31.5 100 100 93 76 61 51 39 28 20 15 11.2 12.7

SP-SM Poorly Graded Sand W/Silt and Gravel

TH08-02-9 35-36.5 100 100 94 85 74 67 57 40 28 22 17.8 15.6 SM-Silty Sand W/Gravel

TH08-03-1 0-1.5 100 100 100 99 98 97 96 92 74 45 28.1 6.7 SM-Silty Sand

TH08-03-2 5.6.5 100 100 100 100 100 100 99 99 94 56 20.4 9.3 SM-Silty Sand

TH08-03-3 10-11.25 100 100 87 83 74 67 52 35 21 11 6.5 4.5 SW-SM Well-Graded Sand W Silt and Gravel

TH08-03-4 11.25-11.50 100 100 84 82 73 56 33 16 7 4 2.2 9.0 SW-Well Graded Sand W/Gravel

TH08-03-5 15-16.5 100 100 100 98 97 94 85 57 29 15 7.3 13.3 SW-SM Well-Graded Sand W Silt

TH08-03-6 20-21.5 100 100 99 86 74 61 41 24 15 9 5.6 11.6 SW-SM Well-Graded Sand W Silt and Gravel

TH08-03-7 25-26 100 100 93 75 60 48 35 26 20 15 11.7 15.4

SP-SM Poorly Graded Sand W/Silt and Gravel

TH08-03-7A 26-26.5 100 100 100 100 97 95 94 93 92 90 82.6 ML-Silt W/Sand

TH08-03-8 30-31.5 100 100 92 83 72 61 45 30 22 14 10.6 12.8

SP-SM Poorly Graded Sand W/Silt and Gravel

TH08-03-9 35-36.5 100 100 86 80 64 52 35 23 15 10 7.2 12.9 SW-SM Well-Graded Sand W Silt and Gravel

Percent Passing by Weight Gravel (inches) Sand (sieve no.) Fines %W boring-sample# Depth 3 1-1/2 3/4 3/8 4 8 16 30 50 100 200 Classification

TH08-03-10 40-41.5 100 100 100 99 88 70 44 23 12 7 5.1 9.9 SW-SM Well-Graded Sand W Silt and Gravel

TH08-03-11 45-46.5 100 100 86 75 61 48 32 18 12 8 5.5 11.0 SW-SM Well-Graded Sand W Silt and Gravel

Note: Atterberg limits not requested

TH08-03

TH08-03

TH08-03

TH08-03

2 May 2008