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EA 2014-1002 La Quinta Square - Evaluation of Drywell Percolation RatesACM La Quinta IV-B LLC c/o The Magellan Group, Inc. 1800 Avenue of the Stars, Suite 105 Los Angeles, California 90067 Evaluation of Drywell Percolation Rates Proposed Retail Development SWC Highway 111 & Simon Drive La Quinta, California August 25, 2014 Submitted By: Earth Systems Southwest 79811B Country Club Drive Bermuda Dunes, California 92203 © 2014 Earth Systems Southwest Unauthorized use or copying of this document is strictly prohibited without the express written consent of Earth Systems Southwest. File No.: 12287-01 Doc. No.: 14-08-742 RECEIVED AUG 2 7 2014 CITY OF LA QUINTA COMMUNITY DEVELOPMENT Earth Systems Southwest August 25, 2014 ACM La Quinta IV-B LLC c/o The Magellan Group, Inc. 1800 Avenue of the Stars, Suite 105 Los Angeles, California 90067 Attention: Mr. Billy Yeung Subject: Evaluation of Drywell Percolation Rates Project: Proposed Retail Development Southwest Corner of Highway 111 and Simon Drive La Quinta, California 79-811B Country Club Drive Bermuda Dunes, CA 92203 (760) 345-1588 (800) 924-7015 FAX (760) 345-7315 File No.: 12287-01 Doc. No.: 14-08-742 Earth Systems Southwest [Earth Systems] is pleased to submit this report concerning our evaluation of drywell percolation rates at the site referenced above. This project was performed at the request of the client to evaluate the anticipated performance of drywells proposed to be installed at the site. Note that the limitations presented at the end of this document are vital to understanding the applicability of the results. We appreciated the opportunity to assist you with this matter. If we can be of further service, please contact us at your convenience at (760) 345-1588. Sincerely, EARTH SYSTEMS SOUTHWEST Scot A. Stormo, PG 4826, CHG 204 Associate Hydrogeologist sas/kp Distribution: 1/Client, via email 1/BD File r STORIIAO (PJV"k CERTIFIED :t 1 HYDROGEOLOGIST RG 4826 � HG 204 f �� EARTH SYSTEMS SOUTHWEST August 25, 2014 TABLE OF CONTENTS File No.: 12287-01 Doc. No.: 14-08-742 1.0 Introduction................................................................................................................. 1 2.0 Purpose, Scope of Work and Methods......................................................................... 1 3.0 Findings........................................................................................................................4 3.1 Soil Types................................................................................................................ 4 3.2 Conductivity [K] Evaluation..................................................................................... 4 3.3 Drywell Evaluation.................................................................................................. 4 4.0 Sensitivity Evaluation................................................................................................... 6 5.0 Conclusions and Recommendations............................................................................. 7 5.1 Capacity...................................................................................................................8 5.2 Design......................................................................................................................8 5.3 Other Considerations.............................................................................................. 9 6.0 Limitations................................................................................................................. 10 References Appendix A - Figures and Tables Appendix B - Boring Logs, Photos, Lab Data and SizePerm Printouts EARTH SYSTEMS SOUTHWEST August 25, 2014 - 1 - File No.: 12287-01 Doc. No.: 14-08-742 1.0 Introduction Earth Systems Southwest [Earth Systems] is pleased to present this report concerning an evaluation of water percolation rates in drywells proposed to be installed at the site. The site I consists of a proposed commercial development on the southwest corner of Highway 111 and Simon Way in La Quinta, California. We understand that the drywells will be used to assist in ( the percolation of storm water, with the goal of percolating a 10-year storm event in 2 days or I less. Figures depicting the site location and proposed layout are presented in Appendix A. This evaluation was particularly interested in the presence of sandy soils classified as SP (sand), I SP-SM (sand with silt) or GP (gravel) in the Unified Soil Classification System [USCS]. These soil types are defined as having less than 12 percent "fines" (silt and clay -size particles), which coincides with the amount of fines at which percolation rates become reasonably fast. For the purposes of this report, SP, SP-SM, and GP layers are referred to as "sandy." Soils with more r than 12 percent fines (SM = silty sand; MIL = silt; CL = clay; and GM = silty gravel on the USCS) Iare referred to as "fine grained" or "silty." I 2.0 Purpose, Scope of Work and Methods The purpose of this project is to evaluate geologic conditions with respect to the subsurface disposal of "clean" water, specifically as it relates to the use of drywells. "Clean" water refers to water free of significant dissolved or suspended oil, chemicals, sediments or debris. This report is not applicable to sewage or "grey" water disposal. The scope of work and methods are summarized below. 1. Two exploratory borings (DW-1 and DW-2) were drilled to a depth of about 60 feet to identify the vertical distribution of soil types conducive to subsurface water disposal. The boring locations were selected to coincide with the anticipated locations of the drywells, though we understand that the proposed drywell locations have been moved. The borings were drilled on August 4, 2014, using a hollow -stem -auger drilling rig. Soil samples were collected at nominal 2-foot intervals using an SPT split -spoon sampler. The sampler was not equipped with rings to allow unobstructed observation of soil distributions. Samples of selected materials were retained in plastic baggies for potential laboratory analysis, with care being taken to avoid comingling soils from different layers. Each interval was photographed and logs of the borings were prepared to document the vertical distribution of soil types. The logs and selected photos are presented in Appendix B. 2. Thirteen soil samples were tested in the laboratory for grain size distribution in general accordance with ASTM C-136-06. The testing focused on sandy layers that appeared capable of percolating water, and included samples from each of the thicker sandy intervals. EARTH SYSTEMS SOUTHWEST ( August 25, 2014 -2- File No.: 12287-01 I Doc. No.: 14-08-742 3. The sieve analyses were used to estimate the hydraulic conductivity [K] of the tested soils. The grain size distribution has empirically been found to be an indicator of the conductivity of a soil, as originally described by Hazen (Hazen, Allen, 1893). The Hazen formula is still the most widely recognized method of its type but other equations have also been published (see Kasenow 2010 for an in depth discussion of twelve methods, and Vukovich and Soro, 1992, for a comparison of these methods to K values derived with pumping tests). Most of the formulas are based on the grain -size diameter of the smallest 10 percent of the material (referred to as the D10) but some formulas use the D17 or D20, the D60 to evaluate uniformity, and the relative compaction. For this evaluation, K values were obtained with the aid of the computer program SizePerm developed by EasySolve Softwear LLC in 1998. The program calculates K values using equations from ten different authors along with the uniformity [n] of the soil (defined as the D60/Dlo). For this project, the Beyer method appeared to be the most applicable (Dlo ranging from 0.06 to 0.6 mm and n between 1 and 20) and was used consistently P for all intervals. An advantage of the Beyer method is that relative compaction is not a Ivariable, reducing the need for manual estimations. The program output for each sample is presented in Appendix B. 4. Observations of soil distributions and the results of the SizePerm analysis were used to develop hypothetical water percolation rates for each sandy interval identified in the borings. The water percolation evaluation considers the thickness of each sandy interval, the depth of each sandy interval below the water inlet (head = i), the drywell radius (R = 2 feet), and the radius of influence of the percolating water (Ro, which is a function of K and i). For this project, the most conservative flow regime was used, where each interval was assumed to be bound by upper and lower confining layers that were impervious, so that the flow rate is described by the equation for a confined aquifer around a point source/sink: Q = Kbi / 528 Log (Ro/R) (Driscoll, 1995) Where; Q = Flow in gallons per minute K = Hydraulic Conductivity in gallons per square foot per day i = Head in feet b = Thickness of interval in feet Ro = Radius of influence in feet R = Radius of drywell in feet The value for Ro is=3i*(k^0.5) (from NAVFAC P-418), with k in 10-4 cm/sec and i in feet. These formulae have been incorporated into a spreadsheet, presented as Table 1. 5. The cumulative percolation rate in a drywell installed to various depths was evaluated by importing the Q obtained for each sandy interval into tables that include consideration of impermeable interbeds (Tables 2 and 3). If distinct interbeds of clay or EARTH SYSTEMS SOUTHWEST August 25, 2014 - 3 - File No.: 12287-01 FDoc. No.: 14-08-742 silt are present within a sandy interval, the Q is reduced by the percentage of each interval comprised of interbedded clay or silt layers (referred to as the Clay/Silt Modified). For this site, clay and silt interbeds were not present, so the Clay/Silt Modifier was 0% for all intervals. The cumulative rate assumes that water will percolate I into each of the soil layers above that interval. This evaluation assumed a Maxwell -style drywell design would be installed, including the following: o Upper portion consists of concrete chamber with sediment filtration system. o Lower portion backfilled with gravel or sand that is much more permeable than surrounding soil. o Filter fabric between the soil and gravel/sand backfill. o No impermeable barrier between soil and drywell backfill. o Diameter of deep boring, 4 feet. o Depth of inlet to deep part of drywell (below current ground surface), 5 feet. o Head at bottom of each drywell interval is the depth to bottom of interval minus the inlet depth. o Head used for percolation rates is the head at bottom of interval minus Yz thickness of the interval. 6. The cumulative percolation rates were compared to the hypothetical storm events the drywells are intended to percolate to estimate the number of days it would take to percolate the target quantity of water using a drywell installed to the indicated depths. At the time of this evaluation, the site was divided into three hydrologic areas (A, B and C) for water control purposes, each with a proposed drywell. The borings drilled as part of this evaluation were not located in close proximity to the currently proposed drywell locations, so the comparison values in Tables 2 and 3 is the maximum volume of water in the three hydrologic areas for both the 10-year and 100-year storm events. 7. The sensitivity of this method to the inherent uncertainties was evaluated and is discussed in Section 4.0. The results of this evaluation are summarized in Tables 1, 2 and 3. The last two tables provide information on the observed layering in the left columns, information on the estimated K values and hypothetical percolation rates in the center columns, and the cumulative percolation capacity estimates in the right columns. EARTH SYSTEMS SOUTHWEST August 25, 2014 - 4 - File No.: 12287-01 Doc. No.: 14-08-742 3.0 Findings r 3.1 Soil Types 1 Soils encountered in the borings consisted of interbedded sand, silt and clay layers. In both borings, fine grained soils were predominant from the surface to a depth of about 22 feet. From 22 to 27 feet, sandy soils classified as SP-SM were present and interbedded with silty soils. Fine-grained soils were again dominant from the base of the upper sandy layer to about 36 (DW-1) to 40 feet (DW-2). Another layer of sandy soil with interbedded silts was present from 36 to 55 feet in boring DW-1, and from 40 to 44 feet in boring DW-2. Each layer of sandy material is considered individually in Tables 2 and 3, and therefore the Clay/Silt modifier is 0%. The sandy layers were predominantly fine-grained, well sorted sands that appear to be aeolian in origin. One cobble was encounter at a depth of 28 feet in DW-2, indicating a high-energy fluvial deposit, but the cobble plugged the sampler and prevented the remainder of the soil from that depth to be evaluated. A sieve analysis of the material from that interval was performed but was discarded as unreliable. A comparison to the other two deep borings drilled onsite as part of the geotechnical report (B- 1 and B-3) found sandy intervals in B-1 from 25 to 30 feet and from 35 to 50 feet, and in B-3 from 20 to 35 feet and from 40 to 50 feet (the maximum depth explored). Therefore, the sandy layers tested from DW-1 and DW-2 appear to be relatively continuous across the site. 3.2 Conductivity [K] Evaluation For the purposes of this evaluation, the sandy layers in DW-1 were divided into eight intervals and in DW-2 they were divided into four intervals, corresponding to the samples on which sieve analyses were performed (note that one interval in DW-2 had two samples analyzed). Interval 3 in DW-1 and interval 1 in DW-2 were actually silt (shown in the tables for comparison purposes), but the other layers were similar to each other with K values ranging from a low of 5.87 x 10-3 cm/sec to 9.10 x 10-3 cm/sec (average 7.0 x 10-3 cm/sec) in DW-1 and 1.86 x 10-3 cm/sec to 7.29 x 10 3 cm/sec (average 5.4 x 10-3 cm/sec) in DW-2. This is a fairly narrow range for K values, considering that natural materials can differ by 10 orders of magnitude. Print-outs of the sieve analyses and the SizePerm program are presented in Appendix B. I 3.3 Drywell Evaluation 1� The drywell evaluation focused on the hypothetical percolation capacity under ideal conditions Lof the sandy intervals discussed. The results of this evaluation, not including a factor of safety, are summarized by location in Tables 2 and 3 and discussed below. L EARTH SYSTEMS SOUTHWEST August 25, 2014 -5- File No.: 12287-01 I Doc. No.: 14-08-742 3.1.1 DW-1 In DW-1, the soil layers were divided into eight intervals for the purposes of this evaluation, coinciding with the number of grain -size analyses performed. Interbedded fine-grained soils I were present to a depth of 22 feet, so the sandy intervals evaluated were as follows: Interval 1— 22 to 25.5 feet Interval 2 — 26.5 to 27.5 feet Interval 3 — 27.5 to 31.5 feet (SM soil, included here mostly for comparison purposes) Interval 4 — 36 to 40 feet Interval 5 — 40 to 44.5 feet Interval 6 — 46.5 to 49.5 feet Interval 7 — 51 to 53 feet Interval 8 — 54 to 55 feet These intervals, except interval 3, were SP-SM soil types with silt concentrations between 5 and 12 percent. For a drywell installed to less than 36 feet (intervals 1 through 3), the cumulative hypothetical percolation rate totals less than 15,000 gpd and would require 5 days to percolate a 10-year storm event. Intervals 4 and 5 are basically a continuous SP-SM layer from 36 to 44.5 feet, and the cumulative hypothetical percolation rate for a drywell installed to 45 feet exceeds 70,000 gpd and is estimated to percolate a 10-year event in about 1 day. Intervals 6 and 7 are also anticipated to be able to percolate a reasonable amount of water, while interval 8 is about one-third the rate of intervals 6 or 7. The hypothetical percolation rate for a drywell installed to 55 feet totals over 100,000 gpd and would percolate at 10-year storm event in less than a day. Note that these values do not contain a factor of safety. Soils from 55 to 60 feet (the total depth explored) did not appear to be able to percolate an appreciable amount of water. 3.1.2 DW-2 In DW-2, the sandy intervals were thinner and less frequent than in DW-1, so the soil layers were divided into four intervals for the purposes of this evaluation. The deepest interval had two grain -size analyses while the others each had one. Interval 1 was an SM soil with a very low percolation rate. Sandy soils started at a depth of 22.5 feet so the intervals anticipated to percolate a reasonable amount of water were as follows: Interval 2 — 22.5 to 23.5 feet Interval 3 — 27 to 30 feet Interval 4 — 40 to 44.5 feet The cumulative hypothetical percolation rate for intervals 2 and 3 totals about 7,500 gpd, which is fairly low. We estimate it would take almost 10 days to percolate a 10-year storm event with L_ I EARTH SYSTEMS SOUTHWEST L August 25, 2014 - 6 - File No.: 12287-01 Doc. No.: 14-08-742 a drywell installed to only 30 feet. The hypothetical percolation rate of interval 4 is almost 30,000 gpd, and the cumulative hypothetical percolation rate for a drywell installed to 44.5 feet is over 35,000 gpd, which we estimate would percolate a 10-year storm event in 2 days. Note that these values do not contain a factor of safety. Soils below 44.5 feet did not appear to be conducive to storm water percolation. 4.0 Sensitivity Evaluation The potential for bias was evaluated by considering the obvious sources of potential error, as discussed below. ' 1. This evaluation is based on empirically derived relationships between grain -size distributions and hydraulic conductivity. Those relationships were derived using engineered soils of a known composition that had been mixed together for that purpose. The natural world is highly variable, and it is likely that the grain -size distribution will vary over short distances both vertically and laterally (particularly in r fluvial sediments, but less so in aeolian deposits). The K value is based on the D10 of the Isoil, not the average grain size, and therefore the inclusion of thin silt interbeds into the grain size analyses will substantially lower the K value derived from that sieve analysis. For example, if a well sorted medium sand with a K of 1x10-1 cm/sec was combined with I, a silt layer 10% its' thickness, the calculated K for the entire interval would be 5x10-3, a reduction of 95%. Since some variability is undoubtedly present, the K values derived f from a sample interval will be biased to underestimate the K values of any well sorted t layers within the sample intervals. Since the K values are based on the square of the effective diameter, this bias can be significant if dissimilar soil types are combined in the I sieve analyses. The net effect is for the K values of mixed soils to be too low, which will results in a Q that underestimates the actual percolation rate for the entire interval. The magnitude of this error could be significant if the soils are heterogeneous within the Lscale of the sampling interval. This results in a low bias that could be significant. 2. The hypothetical percolation rates assume the drywell would operate ideally with no plugging of the soil pores during or after drywell installation. Some plugging is likely, but the degree to which this will affect flow rates is unknown. This results in the Q value being too high by the degree to which plugging will occur. This results in a high bias that could be significant depending on how the drywell is constructed and maintained. 3. The silt and clay layers are assumed to have percolation capacities of 0. While low, the rate will be somewhat higher than 0 and may be appreciable if thin sandy layers are present in the silty intervals. This results in a low bias that is not likely to be significant. 4. At this site, samples were collected every 2 feet using an 18-inch sampler resulting in the observation of a maximum of only 75% of the soil horizons. Layers between the EARTH SYSTEMS SOUTHWEST I August 25, 2014 - 7 - File No.: 12287-01 Doc. No.: 14-08-742 sampled intervals are assumed to be a continuation of the soil above or below the sampled interval, but could be either sandier or siltier than the layers that were observed. This results in an uncertainty of 25% regarding the actual soils present, but it is unlikely the error would be in only one direction. Given that the K value of the most conducive sandy layer is 500% of the least conducive sandy interval, 25% uncertainty in the layering is within the degree of error for other components of the evaluation. This may result in a high or low bias, but is not considered significant. 5. The sandy intervals are assumed to be laterally continuous and extensive enough to store the flow from a 10-year storm event. As observed from the two borings on the site, the layering is not uniform across the site but was similar to a reasonable degree. In other portions of the site, the sandy intervals may be more or less frequent than observed at DW-1 and DW-2. The significance of this will be related to whether the sandy intervals are large enough to store the flow from a design storm event. For this site, the design storm event is only 142,000 gallons per drywell, which is about 19,000 cubic feet of water. The porosity of sandy soils ranges from 26 to 45 percent, depending on the sorting (with better sorting resulting in higher porosity). Using a porosity of 33%, 19,000 cubic feet of water would occupy the pose space of 57,000 cubic feet of soil. The thickness of the sandy layers in DW-1 totaled 19 feet while in DW-2 they totaled 8.5 feet. For DW-1, 57,000 cubic feet of soil would extent to a radius of 30 feet while in DW-2, 57,000 cubic feet would extent to a radius of 46 feet. The continuity of the sandy intervals to these radii appears reasonable. This is not considered to be a bias for the evaluation. 6. The silt and clay intervals that surround the sandy intervals might prevent the water from draining between storm events. However, once the water is stored in the sandy intervals, the surface area available for further percolation is quite large. For example, if the saturated zone extends outward to a distance of 30 feet, the surface area for percolation totals over 2,800 square feet, which is 100 times the surface area (at the radii of the drywell) of a layer 2.2 feet thick. Therefore, as the water spreads out, the surface area for percolation increases dramatically, and the presence of the confining layers becomes less significant. This is not considered a significant bias for the evaluation. 7. Water from one storm event may still be in the soil surrounding the drywell when another storm even occurs. This is not considered an issue because the flow rates were based on saturated conditions. This would negatively affect the flow rate only if the sandy intervals are much less extensive than anticipated. 5.0 Conclusions and Recommendations Based on the results of this evaluation, our conclusions and recommendations are summarized below. EARTH SYSTEMS SOUTHWEST r I August 25, 2014 - 8 - File No.: 12287-01 Doc. No.: 14-08-742 5.1 Capacity Soil conditions at the site consist of interbedded silts and sands with minor amounts of clay. The sandy intervals appear to be wind -blow aeolian deposits that are very well sorted and contain 5 to 12 percent silt interbedded with silty sand and silt layers. • At DW-1, percolating a 10-year storm event in 2 days will require a drywell installed to a depth of at least 40 feet. If a drywell is installed to 55 feet, percolating a 10-year storm event may be possible in 2/3 of a day. Note that this rate does not include a factor of safety. If the factor of safety used as this location is 3 or less, one drywell appears to be capable of percolating the design storm event. As discussed below, the factor of safety is related to how comprehensively the water is filtered before reaching the drywell, so a comprehensive filtration system may pay for itself in reduced drywell costs. • At DW-2, percolating a 10-year storm event in 2 days will require a drywell installed to a depth of 44.5 feet. Installing a deeper drywell is not likely to increase the rate unless it extends beyond 60 feet and encounters sandy soils located beyond the maximum depth of this evaluation. Note that this rate does not include a factor of safety. With a factor of safety added, one drywell will not be adequate at this location. The capacities identified in this evaluation are hypothetical and apply to the locations evaluated. We understand that the drywells may actually be installed in other portions of the site. Sandy layers were found in both borings between 22 and 44 feet, and at similar depths in borings B-1 and B-3 from the geotechnical study, which suggest that similar layers may be present in other portions of the site. Given that the quantity of water to be infiltrated is not very large, drywells in other parts of the site may be able to meet the performance criteria. However, the hypothetical percolation capacities did not exceed the design targets by very much, so it may be prudent to confirm the presence of suitable sandy layers before installing a drywell at a particular location. 5.2 Design Drywells are typically constructed by drilling a large boring to the depth of the receiving layer, and backfilling most of that borehole with gravel. Due to the fine-grained nature of the soil at this site, the gravel backfill will likely be invaded by silt and sand from the surrounding soil, which will: (1) reduce the percolation rate of the drywell, and (2) result in settlement around the drywell. We recommend that filter -fabric or a fine-grained backfill material (such as well - sorted medium -grained sand) be used to keep the native soils out of the drywell backfill. If a fine-grained backfill is used, the specifications for the grain -size distribution should be based on an establish protocol, such as presented in Driscoll's Groundwater and Wells, pages 447 to 448 and 476 to 483 (Driscoll, 1995), or other guidelines as appropriate. EARTH SYSTEMS SOUTHWEST August 25, 2014 - 9 - File No.: 12287-01 Doc. No.: 14-08-742 Typical drywell designs do not allow the level of water in the lower portion of a drywell to be measured, which makes it difficult to evaluate the performance of the drywell over time. If the performance of a drywell needs to be evaluated in the future, or if the drywells are 1 performance tested, it may be valuable to install a small perforated pipe into the gravel at the bottom of the drywell to allow measurement of the water level in the lower part of the drywell. r 5.3 Factor of Safety As discussed in Section 4.0, high and low biases are inherent in this evaluation. The values presented in this report are estimates, and we believe the precision of the hypothetical percolation rates is on the order of ±50 percent. While a low bias may result in a slight over - design of the drywell system, a high bias may result in a water disposal system that does not meet the target criteria. Therefore, we recommend that the drywell be over -designed, such as installing the drywell to the deepest sandy interval, even if the target percolation capacity appears achievable with a shallower drywell. While we were careful not to intentionally overestimate the hypothetical percolation rates of the sandy intervals, we do not guarantee that those percolation rates can be achieved in practice. The presence of fine-grained soil particles is the controlling factor, and fine-grained particles can plug the available porosity either during construction or during use. Maintenance of drainage systems and infiltration structures can be the most critical element in determining the success of a design. They must be protected and maintained from sediment -laden water both during and after construction to prevent clogging. The potential for clogging can be reduced by pre -treating inflow in maintainable forebays, biofilters, oil traps, and sedimentation chambers. Sediment, leaves and other debris must be removed from inlets and traps on a regular basis. Since these and other factors will affect the rate of water percolation over the design life of the structure, it is imperative to apply an appropriate factor of safety to lower the hypothetical water percolation rates presented herein. The value of the FOS is a reflection of both (1) the uncertainty of the analysis, and (2) the potential for clogging after the drywell is installed, and should be selected by the project drainage engineer. 1. Testing the performance of the drywell after installation to quantify the uncertainty of the analysis can serve as the basis for selecting an appropriate FOS. This is particularly true if the drywell's ability to meet its performance target is a critical component of the water infiltration system. If performance testing is performed, we recommend a smaller I perforated pipe (sounding tube) be added to the design to allow measurement of the water level in the lower part of the drywell. 2. A lower FOS can be justified if a comprehensiveness filtration system is used. With a comprehensive filtration system, including bio-swales and siltation basins, a FOS of 3 EARTH SYSTEMS SOUTHWEST August 25, 2014 - 10 - File No.: 12287-01 Doc. No.: 14-08-742 may be appropriate. Without a filtration system, a FOS of 12 may not be sufficient for long-term reliability. C5.4 Other Considerations The Riverside County Design Handbook for Low Impact Development Best Management Practices (2011) contains design recommendations for storm water infiltration. Dry wells are not included because they are technically classified as a Class V injection well regulated by the US EPA Region 9 (and allowable as a "permit by rule"), but they are similar in function to an Infiltration Trench. The Riverside County set -back requirements for an infiltration trench include having at least a 10 foot separation between the bottom of the trench and historic high groundwater. The presence of groundwater does not limit the hypothetical flow rates presented here because the direction of flow is horizontal, but the depth of the drywell may be limited by a regulatory agency to minimize the potential for groundwater contamination. If a 10-foot limit is used, the maximum drywell depth would be 65 feet because historic high groundwater was 75 feet below the current ground surface. (Note that the US EPA Region 9 does not appear to preclude drywells from being installed into groundwater, but a discussion of the regulatory status of drywells is beyond the scope of this study). Percolation of water into the subsurface may result in other deleterious effects, such as hydro - collapse of susceptible soils. This issues should be evaluated as part of the soil engineering report, but at a minimum we recommend that drywells not be installed so close to a building that the soil under the building will become saturated during a single design storm event (approximately 45 feet at this site). After application of the FOS, a single drywell may not be sufficient for one or more areas. Multiple drywells can be used in each area but should be spaced at least 50 feet apart to �. minimize interference across the radius of influence. 6.0 Limitations This report has been prepared for the exclusive use of ACM La Quinta IV-B LLC. The conclusions and recommendations rendered in this report are opinions based on readily available information obtained to date within the scope of the work authorized by the client. The scope of work for this project was developed to address the needs of the client and may not meet the needs of other users. Any other use of or reliance on the information and opinions contained in this report without the written authorization of Earth Systems is at the sole risk of the user. The results contained in this report are based upon the information acquired during the evaluation. It is possible that variations exist beyond or between points explored during the course of the evaluation, and that changes in conditions can occur in the future due to factors not apparent at the time of the field investigation. Note that the hydraulic conductivity of soil EARTH SYSTEMS SOUTHWEST August 25, 2014 - 11- File No.: 12287-01 Doc. No.: 14-08-742 is very sensitive to factors that are highly variable over short distances. Therefore, an appropriate factor of safety should be used in applying the results presented herein. 1 This report does not address permitting requirements by the city, county, state or other 1 jurisdiction. { This evaluation considered subsurface soil and groundwater conditions present at the site at 1 the time of the study. The influence(s) of post -construction changes to these conditions, such as the addition of other sources of subsurface water, may influence future performance of the proposed project. It should be recognized that definition and evaluation of subsurface conditions are difficult; conclusions and recommendations are based on incomplete knowledge of the subsurface due to the limited data obtained from field studies. The availability and broadening of knowledge and professional standards applicable to engineering services are continually evolving. As such, our services are intended to provide the client with a source of r professional advice, opinions and recommendations based on the information obtained within Ithe scope of work at the time the services were performed. If the proposed construction changes, the conclusions and recommendations in this report are not considered valid unless the changes are reviewed and are either modified or approved in writing by Earth Systems. The recommendations provided in this report are based on the assumption that Earth Systems I will be retained to provide observation during construction to evaluate our recommendations in relation to the apparent site conditions at that time. If we are not provided with this opportunity, Earth Systems assumes no responsibility for the suitability of our recommendations. In addition, if there are any changes in the field to the plans and specification, the Client must obtain written approval from Earth System' engineer that such changes do not affect our recommendations. Earth Systems should be provided the opportunity for a general review of final design and specifications in order that earthwork and foundation recommendations may be properly i interpreted and implement in the design and specifications. If Earth Systems is not accorded l the privilege of making this recommended review, we can assume no responsibility for misinterpretation of our recommendations. The owner or the owner's representative has the f responsibility to provide the final plans requiring review to Earth System's attention so that we l may perform our review. The services performed by Earth Systems have been conducted in a manner consistent with the level of care and skill ordinarily exercised by members of our profession currently practicing under similar conditions in the site vicinity. No warranty, express or implied, is offered. �1T011 EARTH SYSTEMS SOUTHWEST r August 25, 2014 - 12 - File No.: 12287-01 Doc. No.: 14-08-742 REFERENCES Bouwer, Herman, 2002, Artificial Recharge of Groundwater: Hydrogeology and Engineering, Hydrogeology Journal, Volume 10, pages 121-142. Driscoll, Fletcher, D, 1995, Groundwater and Wells, Second Edition, published by Johnson Screens, St. Paul, Minnesota, 55112 EasySolve Software LLC, 1998, SizePerm computer program. Hazen, Allen, 1893, Some Physical Properties of Sand and Gravels, Massachusetts State Board of Health, 241h Annual Report. Kasenow, Michael, 2010, Determination of Hydraulic Conductivity from Grain Size Analysis. Water Resources Publications, LLC, Highlands Ranch, Colorado. NAVFAC, DM 7.1 Soil Mechanics, 1986, Tables 14 and 15 (after Horslev, 1949). NAVFAC P-418, 1983, Dewatering and Groundwater Control, page 4-24. Riverside County Flood Control and Water Conservation District, 2011, Design Handbook for Low Impact Development Best Management Practices. Vokovic, Milan. and Soro, Andjelko., 1992, Determination of Hydraulic Conductivity of Porous Media from Grain Size Distribution. Water Resources Publications, LLC, Highlands Ranch, Colorado. Zanger, Carl, 1953, Theory and Problems of Water Percolation, Engineering Monographs No. 8, US Bureau of Reclamation. EARTH SYSTEMS SOUTHWEST APPENDIX A FIGURES AND TABLES EARTH SYSTEMS SOUTHWEST ��" tom• t `S 1 *�(3 ti9aM • tt.• a l a•w � ♦ 1 ti V •. I - L Via.+• �t It Approximate Site ocation a' . 7Ma.•1� I 1 � - - �:.- � i-� � '^" __ � r:..�. '•� � � ' _ sa ..,. .� .tee.. // d7 im 91 i..J�ma •.- 1 ' Figure 1 LEGEND Site Location Ma Proposed Retail Development Approximate Site Location Highway 111 & Simon Drive La Quinta, Riverside County, California Approximate Scale: V = 1 Mile Earth Systems Southwest 0 1 Mile 2 Miles I 8/25/2014 File No.: 12287-01 LEGEND Approximate Drywell Boring Locations DW-2 0 Approximate Percolation Test Locations P-3 Approximate Scale: 1" = 75' 0 75' 150' TA A -I ci Figure 2 Test Location Ma Proposed Retail Development Highway 111 & Simon Drive La Quinta, Riverside County, California rfikkt Earth Systems Southwest 8/25/2014 File No.: 12287-01 Table 1 - Hypothectical Water Percolation Rates Location ID Interval (feet) Thickness (b) (feet) Average Head (i) (ft) Conductivity (K) Radius of Influence (Ro) (feet) Percolation (Q) Top Bottom cm/sec in/hr gpd/ft^2 gpm gpd AF/day 22.0 25.5 3.5 22.25 5.99E-03 8.5 127 517 7.8 11,184 0.03 26.5 27.5 1.0 23 6.44E-03 9.1 137 554 2.4 3,508 0.01 27.5 31.5 4.0 28.5 5.63E-05 0.1 1 64 0.2 246 0.00 DW-1 36.0 40.0 4.0 37 9.10E-03 12.9 193 1059 19.9 28,597 0.09 40.0 44.5 4.5 41.75 7.26E-03 10.3 154 1067 20.1 28,925 0.09 46.5 49.5 3.0 46 6.05E-03 8.6 128 1073 12.3 17,689 0.05 51.0 53.0 2.0 49 8.16E-03 11.6 173 1328 11.4 16,388 0.05 54.0 55.0 1.0 50.5 5.87E-03 8.3 124 1161 4.3 6,203 0.02 9.0 15.5 6.5 13.75 1.10E-04 0.2 2 43 0.3 426 0.00 DW-2 22.5 23.5 1.0 19 7.13E-03 10.1 151 481 2.3 3,290 0.01 27.0 30.0 3.0 26.5 1.86E-03 2.6 39 343 2.7 3,828 0.01 40.0 44.5 4.5 41.75 7.29E-03 10.3 155 1069 20.2 29,035 0.09 Drywell Radius 2 Depth of Inlet 5 Design (feet) (R) (feet) Notes: Conductivities are based on sieve analyses Radius of Influence (Ro) is = 3'i'(KA0.5) with K in 10-4 cm/sec and i in feet Capacity (gpm) = Kib / 528 Log (Ro/R) 1 12287-01 Drywell Tables.xlsx Earth Systmes Southwest r Table 2 - Boring DW-1 Hypothetical Water Percolation Capacity Using a Drywell Z Top 22 feet Soil Type SP-SM Cumulative Hypothetical Percolation Rate Comparison to Design Storm Events (Days to Infiltrate) Bottom 25.5 feet Thickness 3.5 feet K Value (From Beyer) 5.99E-03 cm/sec Clay/Silt Modifier 0% percent 127 d/ft2 gpd gpm 10 year 100 year c Apparent Thickness 3.50 feet Hypothetical Water Percolation Rate* 11,184 gpd 11,184 7.8 6.55 12.70 Percolation Surface Area 44 sq. ft. 7.8 gpm N °? Top 26.5 feet Soil Type SP-SM Cumulative Hypothetical Percolation Rate Comparison to Design Storm Events (Days to Infiltrate) Bottom 27.5 feet Thickness 1 feet K Value (From Beyer) 6.44E-03 cm/sec Clay/Silt Modifier 0% percent 137 d/ft2 gpd gpm 10 year 100 year c Apparent Thickness 1.00 feet Hypothetical Water sq. ft. Percolation Rate* 3,508 gpd 14,692 10.2 4.99 9.67 Percolation Surface Area 13 2.4 gpm Top 27.5 feet Soil Type SM Cumulative Hypothetical Percolation Rate Comparison to Design Storm Events (Days to Infiltrate) Bottom 31.5 feet Thickness 4 feet K Value (From Beyer) 5.63E-05 cm/sec Clay/Silt Modifier 0% percent 1 d/ft2 gpd gpm 10 year 100 year C Apparent Thickness 4.00 feet Hypothetical Water Percolation Rate* 246 gpd 14,938 10.4 4.91 9.51 Percolation Surface Area 50 sq. ft. 0.2 gpm 2 0) Top 36 feet Soil Type SP-SM Cumulative Hypothetical Percolation Rate Comparison to Design Storm Events (Days to Infiltrate) Bottom 40 feet Thickness 4 feet K Value (From Beyer) 9.10E-03 cm/sec Clay/Silt Modifier 0% percent 193 d/ft2 gpd gpm 10 year 100 year c Apparent Thickness 4.00 feet Hypothetical Water Percolation Rate* 26,597 gpd 43,535 30.2 1.68 3.26 Percolation Surface Area 50 s . ft. 19.9 gpm r Q Top 40 feet Soil Type SP-SM Cumulative Hypothetical Percolation Rate Comparison to Design Storm Events (Days to Infiltrate) Bottom 44.5 feet Thickness 4.5 feet K Value (From Beyer) 7.26E-03 cm/sec Clay/Silt Modifier 0% percent 154 d/ft2 gpd gpm 1 o year 100 year C Apparent Thickness 4.50 feet Hypothetical Water Percolation Rate* 28,925 gpd 72,460 50.3 1.01 1.96 Percolation Surface Area 57 sq. ft. 20.1 QDM Z Top 46.5 feet Soil Type SP-SM 14Cumulative Hypothetical Percolation Rate Comparison to Design Storm Events (Days to Infiltrate) Bottom 49.5 feet Thickness 3 feet K Value (From Beyer) 6.05E-03 cm/sec Clay/Silt Modifier 0% percent 128 d/ft2 gpd gpm 10 year 100 year c Apparent Thickness 3.00 feet Hypothetical Water Percolation Rate* 17,689 gpd 90,149 62.6 0.81 1.58 Percolation Surface Area 38 sq. ft. 12.3 gpm F7- op 51 feet Soil Type SP-SM Cumulative Hypothetical Percolation Rate Comparison to Design Storm Events (Days to Infiltrate) ttom 53 feet kness 2 feet K Value (From Beyer) 8.16E-03 cm/sec lt Modifier 0% percent 173 d/ft2 gpd gpm 10 year 100 year t Thickness 2.00 feet Hypothetical Water Percolation Rate* 16,388 gpd 106,537 74.0 0.69 1.33 Surface Area 25 s . ft. 11.4 g m W Q) E Top 54 feet Soil Type SP-SM Cumulative Hypothetical I Percolation Rate Comparison to Design Storm Events (Days to Infiltrate) Bottom 55 feet Thickness 1 feet K Value (From Beyer) 5.87E-03 cm/sec Clay/Silt Modifier 0% 1 percent 124 d/ft2 gpd gpm 10 year 100 year Apparent Thickness 1.00 feet Hypothetical Water Percolation Rate* 6,203 gpd 112,740 78.3 0.65 1.26 Percolation Surface Area 13 sq. ft. 4.3 gpm I Notes: K values obtained from SizePerm program * Hypothetical water percolation rate considers the K of the soil, diameter of the drywell, the head of water for that interval, the thickness of the interval, the presence of interbedded clay and silt layers, and the decrease in head as the water moves radially away from the drywell. The hypothetical percolation capacities do not include a "factor of safety" and assumes ideal "clean water" infiltration conditions. 10-year storm event, in Acre Feet = 0.225 10-year storm event, in gallons = 73,282 100-year storm event, in Acre Feet = 0.436 100-year storm event, in gallons = 1 142,068 Abbreviations: gpd = gallons per day; gpm = gallons per minute, gpd/ft2 = gallons per day per square foot 12287-01 Drywell Tables.xlsx Earth Systems Southwest r r Table 3 - Boring DW-2 Hypothetical Water Percolation Capacity Using a Drywell Top 9 feet Soil Type SM Cumulative Hypothetical Percolation Rate Comparison to Design Storm Events (Days to Infiltrate) Bottom 15.5 feet Thickness 6.5 feet K Value (From Beyer) 1.10E-04 cm/sec Clay/Silt Modifier 0% percent 2 d/ft2 gpd gpm 10 year 100 year Apparent Thickness 6.50 feet Hypothetical Water Percolation Rate* 426 gpd 426 1 0.3 172.07 333.59 Percolation Surface Area 82 sq. ft. 0.3 gpm N Top 22.5 feet Soil Type SP-SM Cumulative Hypothetical Percolation Rate Comparison to Design Storm Events (Days to Infiltrate) Bottom 23.5 feet Thickness 1 feet K Value (From Beyer) 7.13E-03 cm/sec Clay/Silt Modifier 0% percent 151 d/ft2 gpd gpm 10 year 100 year c Apparent Thickness 1.00 feet Hypothetical Water Percolation Rate* 3,290 gpd 3,716 2.6 19.72 38.23 Percolation Surface Area 13 sq. ft. 2.3 gpm CO Z d Top 27 feet Soil Type SP-SM Cumulative Hypothetical Percolation Rate Comparison to Design Storm Events (Days to Infiltrate) Bottom 30 feet Thickness 3 feet K Value (From Beyer) 1.86E-03 cm/sec Clay/Silt Modifier 0% percent 39 d/ft2 gpd gpm 10 year 100 year c Apparent Thickness 3.00 feet Hypothetical Water Percolation Rate* 3,828 gpd 7,544 5.2 9.71 18.83 Percolation Surface Area 38 sq. ft. 2.7 gpm Top 40 feet Soil Type SP-SM Cumulative Hypothetical Percolation Rate Comparison to Design Storm Events (Days to Infiltrate) Bottom 44.5 feet Thickness 4.5 feet K Value (From Beyer) 7.29E-03 cm/sec Clay/Silt Modifier 0% percent 155 d/ft2 gpd gpm 10 year 100 year C Apparent Thickness 4.50 feet Hypothetical Water sq. ft. Percolation Rate* 29,035 gpd 36,579 25.4 2.00 3.88 Percolation Surface Area 57 20.2 m Notes: K values obtained from SizePerm program using Beyer formula * Hypothetical water percolation rate considers the K of the soil, diameter of the drywell, the head of water for that interval, the thickness of the interval, the presence of interbedded clay and silt layers, and the decrease in head as the water moves radially away from the drywell. The hypothetical percolation capacities do not include a "factor of safety" and assumes ideal "clean water" infiltration conditions. 7-1 10-year storm event, in Acre Feet = 0.225 10-year storm event, in gallons = 73,282 100-year storm event, in Acre Feet = 0.436 100-year storm event, in gallons = 1 142,068 Abbreviations: gpd = gallons per day; gpm = gallons per minute; gpd/ft= gallons per day per square foot 1 12287-01 Drywell Tables.xlsx Earth Systems Southwest F I L APPENDIX B BORING LOGS, PHOTOGRAPHS, LAB DATA AND SIZEPERM PRINTOUTS EARTH SYSTEMS SOUTHWEST r r Earth Systems Southwest 79-811 B Country Club Drive, Bennuda Dunes. CA 92203 Phone (760) 345-1588, Fax (760) 345-7315 Boring No: DW-1 Drilling Date: August 4, 2014 Project Name Proposed Retail, Hwy I I I & Simon Dr., La Quinta Drilling Method: 6" USA Project Number: 12287-01 Drill Type: Mobile Drill, Model B-61 Boring Location: See Figure 2 Logged By: Rich liowe Sample Type Penetration °w'' Description of Units Resistance q a •o y Note: The stratification lines shown represent the � Q Y q (Blows/6") c approximate boundary between soil and/or rock types be N Ca U and the transition may gradational. -5 - ]0 - 15 - 20 - 25 - 30 - 35 - 40 - 45 - 50 - 55 - 60 - 65 - 70 - 75 - 80 Page 1 of 1. Graphic Trend Blow Dry Count Density SM SILTY SAND: brown, loose, moist, fine grained sand, interbedded sandy silt, each layer was relatively uniform 2, 2, 2 3, 3, 5 CL SILTY CLAY: gray, stiff, moist 3, 3, 4 3, 4, 4 ML SANDY SILT: gray brown, medium dense, moist, fine grained 3, 3, 5 sand E CL SILTY CLAY: gray brown, stiff, moist, uniform 4, 6, 6 SM 5, 6, 7 SILTY SAND: brown, medium dense, moist, fine grained sand, Sp-SM 7, 10, 13 uniform 9, 11, 11 7, 12, 12 POORLY GRADED SAND WITH SILT: brown, dense, moist, fine grained sand, uniform SM/ML El 10, 12, 12 SP-SM INTERBEDDED SILTY SAND/SANDY SILT: brown, dense, El 719,13 damp, fine grained sand SDI 8, 9, 9 6, 8, 9 POORLY GRADED SAND: brown, dense, damp, fine grained sand �1L 8, 11, 11 Sp-SM SILTY SAND: as above 12, 15, 15 SANDY SILT: brown to yellow brown, dense, damp, 9, 12, 13 interbedded with thin SM layers El 12, 14, 19 POORLY GRADED SAND WITH SILT: as above El 8,12,15 ll, 19, 19 SM SILTY SAND: as above SP-SM POORLY GRADED SAND WITH SILT: as above 11, 19, 20 El 13, 22, 28 SM SILTY SAND: as above EJ 7, 10, 10 SP-Sm POORLY GRADED SAND WITH SILT: as above 9, 11, 12 SANDY SILT: as above 7, 7,9 EJ 8, 9, 9 ESP-Simi POORLY GRADED SAND WITH SILT: as above 7, 8, 10 ML SANDY SILT: as above Suring completed at 61 1/2 feet Back lilled with native, Patched with AC cold patch No groundwater encountered I I Earth Systems 1� Southwest 79-811 B Country Club Drive. Bennuda Dunes, CA 92203 Phone(760)345-1588.Fax (760)345-7315 Boring No: DW-2 Drilling Date: August 4, 2014 Project Name Proposed Retail, Hwy I I I & Simon Dr., La Quinta Drilling Method: 6" HSA Project Number: 12287-01 Drill Type: Mobile Drill, Model B-61 Boring Location: See Figure 2 Logged By: Rich Howe _ Sample Type Penetration 2 Description of Units Page 1 of 1 Resistance p ¢ •= aci Note: The stratification lines shown represent the o E Cn Cn o approximate boundary between soil and/or rock types Graphic Trend p m C) (Blows/6") � Q U and the transition may be gradational. Blow Dry Count Density ML SILT: brown, medium dense, moist, with interbeded fine grained sandy silt 5 2, 3, 4 SM SILTY SAND: light gray brown, medium dens,e moist, fine 10 4, 4, 6 grained sand, uniform 3, 4, 5 15 4, 4, 5 MUCL SILT AND CLAY: light gray, loose, damp 3, 3, 3 4, 6, 7 oo 20 4, 5, 6 7, 10, 11 Sp-SM POORLY GRADED SAND WITH SILT: yellow brown, dense, 25 5 4 7 damp, fine grained sand CL SILTY CLAY: brown, stiff, damp 6, 10,13 SP-SM ]2, 12, 12 30 POORLY GRADED SAND WITH SILT: yellow brown, dense, SM 5, 8, 9 damp, fine grained sand 4, 5, 8 ML SILTY SAND: brown, stiff, damp 35 5, 6, 7 SANDY SILT: as above 4,5,6 5, 8, 10 SM SILY SAND: as above 40 7, 10, 13 SP-SM POORLY GRADED SAND WITH SILT: as above 8, 14, 16 45 8, 12, 14 SM SILTY SAND: as above 9, 11, 13 ML SILT: as above 8, 9, 10 50 6 10 12 SM SILTY SAND: as above 6, 8, 8 ML SILT: brown, dense, damp 55 .7, 11, 9 6, 7, 8 8, 9, 10 60 6, 8, 12 65 70 75 Boring completed at 61 1/2 feet BacktIlled with native, Patched with AC cold patch No groundwater encountered an g1 4 5 6 g .:.j Photo 1: Close-up of soil sample from 26 to 27.5 feet in DW-1. Bottom of sampler is on the left side of photo. Note sandy layer in middle and tighter silt layer at left. Photo 2: Close-up of soil sample from DW-1 at 42 feet. Note fine well -sorted sand on white -board. Bottom of sampler is on the left side of the photo. jft Earth Systems Southwest 08/25/ 4 7 File No.: 12287-01 Page 1 of 2 Photographs Proposed Retail Development Highway III and Simon Drive La Quinta, riverside County, California 'Y S �-�i'}• F V Photo 3: Close-up of soil sample from 22 feet from DW-2. Bottom of sampler is on left side of photo. Note uniform grain size. Photo 4: Close-up of soil sample from 28 feet in DW-2. Note large cobble that plugged sampler. Bottom of sampler is on the left. 0 %, Earth Systems Southwest 08/25/14 File No.: 12287-01 Page 2 of 2 Site Photographs Proposed Retail Development Highway 111 and Simon Drive La Quinta, riverside County, California File No.: 12287-01 August 13, 2014 PARTICLE SIZE ANALYSIS ASTM D-422-63 Reapproved 2007 Job Name: Proposed Retail Center Sample ID: DW-1 @ 22 feet Description: Sand w/Silt (SP-SM) 100 90 80 70 AO c 00 c §0 a> a 30 20 10 0 Sieve Percent Size Passing 1-1 /2" 100 l" 100 3/4" 100 1 /2" 100 3/8" 100 #4 100 #8 100 #16 99 #30 94 #50 63 #100 28 #200 10 % Gravel: 0 % Sand: 90 % Silt: 6 % Clay (3 micron): 4 (Clay content by short hydrometer method) 100 10 1 0.1 Particle Size ( rum) 0.01 0.001 EARTH SYSTEMS SOUTHWEST I File No.: 12287-01 August 13, 2014 PARTICLE SIZE ANALYSIS ASTM D-422-63 Reapproved 2007 Job Name: Proposed Retail Center Sample ID: DW-1 @ 27 Description: Sand w/Silt (SP-SM) 100 90 80 70 §,0 040 §0 30 20 10 0 Sieve Percent Size Passing 1-1 /2" 100 1" 100 3/4" 100 1 /2" 100 3/8" 100 #4 100 #8 100 #16 98 #30 86 450 52 #100 22 #200 9 % Gravel: 0 % Sand: 91 % Silt: 4 % Clay (3 micron): 5 (Clay content by short hydrometer method) 100 10 1 0.1 Particle Size ( mm) 0.01 0.001 EARTH SYSTEMS SOUTHWEST Idle No.: 12287-01 August 13, 2014 PARTICLE SIZE ANALYSIS ASTM D-422-63 Reapproved 2007 Job Name: Proposed Retail Center Sample ID: DW1 @ 30 feet Description: Silty Sand (SM) Sieve Percent Size Passing 1 I 1-1/2" 100 1" 100 3/4" 100 1/2" 100 3/8" 100 #4 100 l l #8 100 #16 100 % Gravel: 0 #30 99 % Sand: 82 450 91 % Silt: 12 # 100 56 % Clay (3 micron): 6 • 4200 18 (Clay content by short hydrometer method) 100 90 80 70 90 c 0 c -10 a� a 30 20 10 0 100 10 1 0.1 Particle Size (MM) 0.01 0.001 EARTH SYSTEMS SOUTHWEST File No.: 12287-01 August 13, 2014 PARTICLE SIZE ANALYSIS ASTM D-422-63 Reapproved 2007 Job Name: Proposed Retail Center Sample ID: DWl @ 38 Description: Poorly Graded Sand w/Silt (SP-SM) 100 90 80 70 90 c 0 c $10 a> a 30 20 10 0 Sieve Percent Size Passing 1-1 /2" 100 1" 100 3/4" 100 1 /2" 100 3/8" 100 #4 100 #8 100 #16 100 #30 100 #50 77 #100 22 4200 6 % Gravel: 0 % Sand: 94 % Silt: 2 % Clay (3 micron): 4 (Clay content by short hydrometer method) 100 10 1 0.1 Particle Size ( rnrn) 0.01 0.001 EARTH SYSTEMS SOUTHWEST File No.: 12287-01 August 13, 2014 PARTICLE SIZE ANALYSIS ASTM D-422-63 Reappro�'ed 2007 Job Name: Proposed Retail Center Sample 1D: DWl @ 42 feet Description: Poorly Graded Sand w/Silt (SP-SM) Sieve Percent Size Passing l-1/2" 100 1" 100 3/4" 100 1 /2" 100 3/8" 100 #4 100 1 #8 100 #16 100 % Gravel: 0 #30 100 % Sand: 92 1 1 #50 82 % Silt: 4 #100 29 % Clay (3 micron): 4 t #200 8 (Clay content by short hydrometer method) El L L 100 90 80 70 90 c 040 c §0 a) a 30 20 10 0 100 10 1 0.1 Particle Size (rnrn) EARTR SYSTEMS SOUTHWEST 0.01 0.001 File No.: 12287-01 PARTICLE SIZE ANALYSIS August 13, 2014 ASTM D-422-63 Reapproved 2007 Job Name: Proposed Retail Center Sample ID: DWI @ 48 feet Description: Poorly Graded Sand w/Silt (SP-SM) Sieve Percent Size Passing 1-1 /2" 100 1" 100 3/4" 100 1 /2" 100 3/8" 100 #4 100 #8 100 #16 100 % Gravel: 0 #30 97 % Sand: 90 #50 66 % Silt: 7 #100 28 % Clay (3 micron): 3 #200 10 (Clay content by short hydrometer method) 0.01 0.001 EARTH SYSTEMS SOUTHWEST File No.: 12287-01 PARTICLE SIZE ANALYSIS August 13, 2014 ASTM D-422-63 Reapproved 2007 Job Name: Proposed Retail Center Sample 1D: DWI @ 52 feet Description: Poorly Graded Sand w/Silt (SP-SM) Sieve Percent Size Passing 1-1/2" 100 1" 100 3/4" 100 1 /2" too 3/8" 99 #4 99 #8 99 # 16 99 % Gravel: 1 #30 95 % Sand: 93 #50 63 % Silt: 3 #100 22 % Clay (3 micron): 4 #200 7 (Clay content by short hydrometer method) 0.01 0.001 EARTH SYSTEMS SOUTHWEST r r r r r File No.: 12287-01 August 13, 2014 PARTICLE SIZE ANALYSIS :\ST\i D-422-63 Reappro\ed 2007 Job Name: Proposed Retail Center Sample ID: DWI @ 54 feet Description: Poorly Graded Sand w/Silt (SP-SM) Sieve Percent Size Passing 1-1 /2" 100 1" l00 3/4" 100 1 /2" 100 3/8" l00 #4 100 #8 100 #16 100 % Gravel: 0 #30 96 % Sand: 90 #50 58 % Silt: 6 #100 28 % Clay (3 micron): 4 #200 10 (Clay content by short hydrometer method) 100 90 80 70 90 C 040 C _$0 N a 30 20 10 0 100 10 1 0.1 Particle Size ( mm) 0.01 0.001 EARTI I SYSTEMS SOUTHWEST l File No.: 12287-01 August 13, 2014 PARTICLE SIZE ANALYSIS ASTM D-422-63 Reapproved 2007 t Job Name: Proposed Retail Center Sample ID: DW2 @ 14 feet Description: Silty Sand (SM) l Sieve Percent Size Passing l 1-1/2" 100 1" 100 3/4" 100 I 1 /2" 100 3/8" 100 #4 100 #8 100 #16 100 % Gravel: 0 #30 100 % Sand: 83 #50 98 % Silt: 12 #100 70 % Clay (3 micron): 5 ##200 17 (Clay content by short hydrometer method) 100 90 80 70 A0 c in 0 c §0 a) o_ 30 20 10 0 100 10 1 0.1 0.01 0.001 Particle Size (mm) EARTH SYSTEMS SOUTHWEST 1 1 1 1 1 1 1 1 I 1 1 1 1 I File No.: 12287-01 August 13, 2014 PARTICLE SIZE ANALYSIS ASTM D-422-63 Reapproved 2007 Job Name: Proposed Retail Center Sample ID: DW2 @ 22 feet Description: Poorly Graded Sand w/Silt (SP-SM) 100 90 80 70 510 c U) ciao 80 CL 30 20 10 0 Sieve Percent Size Passing 1-1/2" 100 1" 100 3/4" 100 1 /2" 100 3/8" 100 #4 100 #8 100 #16 99 #30 93 450 58 #100 24 #200 8 % Gravel: 0 % Sand: 92 % Silt: 3 % Clay (3 micron): 5 (Clay content by short hydrometer method) 100 10 1 0.1 Particle Size (mm) 0.01 0.001 EARTH SYSTEMS SOUTHWEST File No.: 12287-01 August 13, 2014 PARTICLE SIZE ANALYSIS ASTM D-422-63 Reapproved 2007 Job Name: Proposed Retail Center Sample ID: DW2 @ 27 feet Description: Poorly Graded Sand w/Silt (SP-SM) Sieve Percent Size Passing 1-1 /2" 100 I" 100 3/4" 100 1 /2" 100 3/8" 100 #4 100 #8 100 # 16 99 % Gravel: 0 #30 94 % Sand: 89 #50 66 % Silt: 6 #100 31 % Clay (3 micron): 5 #200 11 (Clay content by short hydrometer method) 0.01 0.001 EARTH SYSTEMS SOUTHWEST 1 1 1 1 1 File No.: 12287-01 August 13, 2014 PARTICLE SIZE ANALYSIS ASTM D-422-63 Reapproved 2007 Job Name: Proposed Retail Center Sample ID: DW2 @ 40 feet Description: Poorly Graded Sand w/Silt (SP-SM) Sieve Percent Size Passing 1-1 /2" 100 1" 100 3/4" 1.00 1 /2" 100 3/8" 100 #4 100 #8 100 #16 100 % Gravel: 0 #30 100 % Sand: 92 #50 78 % Silt: 4 #100 28 % Clay (3 micron): 4 #200 8 (Clay content by short hydrometer method) 100 90 80 70 90 C 0 C §0 (D 30 20 10 0 100 10 1 0.1 Particle Size ( mrTi) 0.01 0.001 EARTH SYSTEMS SOUTHWEST 1 1 1 1 1 I I I F Ile No.: 12287-01 PARTICLE SIZE ANALYSIS August 13, 2014 ASTM D-422-63 Reapproved 2007 Job Name: Proposed Retail Center Sample ID: DW2 @ 42 feet Description: Poorly Graded Sand w/Silt (SP-SM) Sieve Percent Size Passing l-l/2" 100 l" 100 3/4" 100 l /2" 100 3/8" 100 #4 100 #8 100 #16 100 % Gravel: 0 #30 100 % Sand: 92 #50 69 % Silt: 4 #100 25 % Clay (3 micron): 4 #200 8 (Clay content by short hydrometer method) 100 90 80 70 &0 c a0 §0 a) a 30 20 10 0 100 10 1 0.1 Paitide Size (nun) 0.01 0.001 EARTH SYSTEMS SOUTHWEST Earth Systems Southwest Bermuda Dunes, California Sample ID: DW-I @ 22' Sample Date: August 4, 2014 Interval: 22 HYDRAULIC CONDUCTIVITY CALCULATED FROM SIEVE ANALYSIS SIEVE ANALYSIS BEYER METHOD Percent Diameter K = g • C • rp(n) • d? where: g = 9.81 m/s' v v = 1.14 mmz/s 4 0.003 K = 5.99E-03 cm/sec 500 10 0.074 C = 0.06 • log 28 0.15 77 63 0.3 rp(n) =1 0.68 n=0.255•(1+0.837 94 q = d601 dio 100 2.36 de = dlo SIZE DISTRIBUTION VARIABLES K - I lydraulic conductivity (cm/s) Percent Size g -Acceleration due to gravity m/s 0 0 +3" Gravel v -Viscosity (mmz/s) 90 Sand C - Coefficient — 6 Silt (p(n) - Function of porosity — 4 Clay n - Porosity * — 77 - Uniformity — d, - Effective grain diameter (mm) d,o - Diameter at 10% (mm) d60 - Diameter at 60% (mm) * May substitute measured porosity EasySol ve Software LLC W�P.O. Box 3247, Eagle, Colorado 81631 www.easysolve.com (970) 319-1591 8/14/2014 1 1 I 1 1 Earth Systems Southwest Bermuda Dunes, California Sample ID: DW-1 @ 27' Sample Date: August 4, 2014 Interval: 27 HYDRAULIC CONDUCTIVITY CALCULATED FROM SIEVE ANALYSIS SIEVE ANALYSIS BEYER METHOD Percent Diameter K = g • C • (p(n) • d? where: g = 9.81 m/sz 0.001 v v = l .14 mmz�s 50 0.003 K = 6.44E-03 cm/sec 500 9 0.074 C = 0.06 • log 22 0.15 77 52 0.3 (p(n) = 1 86 0I.68 n = 0.255 • (I + 0.83" 98 = d601dio 100 2.36 de = d10 SIZE DISTRIBUTION VARIABLES K - Hydraulic conductivity (cm/s) Percent Size g - Acceleration due to gravity (m/s2 0 0 +3" Gravel v - Viscosity (mm2/s) 91 Sand C - Coefficient — 4 Silt (p(n) - Function of porosity — 5 Clay n - Porosity * — q - Uniformity — de - Effective grain diameter (mm) dlo - Diameter at 10% (mm) d60 - Diameter at 60% (mm) * May substitute measured porosity EasySolve Software LLC Fc-nwCJ' P O. Box 3247, Eagle, Colorado 81631 www.easysolve.com (970) 319-1591 8/14/2014 1 1 I 1 I I I 1 1 1 1 1 J I Earth Systems Southwest Bermuda Dunes, California Sample ID: DW-I @ 30' Sample Date: August 4, 2014 Interval: 30 HYDRAULIC CONDUCTIVITY CALCULATED FROM SIEVE ANALYSIS SIEVEANALYSIS BEYER METIIOD Percent Diameter K = S • C • �9(n) • d z where: g = 9.81 m/s z v v = 1.14 mm 2 /s 6 0.003 K = 5.63E-05 cm/sec 500 18 0.074 C = 0.06 • log 56 0.15 77 91 0.3 (p(n) = 1 n=0.255-0+0.83") 199 10.6 = d6o 1dlo de = d10 SIZE DISTRIBUTION VARIABLES Percent Size K - Hydraulic conductivity (cm/s) g - Acceleration due to gravity m/s2 0 83 Gravel Sand v -Viscosity (MmZ/s) 11 Silt C - Coefficient — 6 Clay (p(n) - Function of porosity — n - Porosity * — 77 - Uniformity — d, - Effective grain diameter (mm) d10 - Diameter at 10% (mm) d60 - Diameter at 60% (mm) * May substitute measured porosity EasySol ve Software LLC wCv' P O. Box 3247, Eagle, Colorado 81631 www.easysolve.com (970) 319-1591 8/13/2014 Earth Systems Southwest Bermuda Dunes, California Sample ID: DW-I @ 38' Sample Date: August 4, 2014 Interval: 38 HYDRAULIC CONDUCTIVITY CALCULATED FROM SIEVE ANALYSIS SIEVE ANALYSIS BEYER METHOD Percent Diameter K 2g • C • rp(n) • d2 where : g = 9.81 m/s2 v v =1.14 mm 2 /s 4 0.003 K = 9.10E-03 cm/sec 500 6 0.074 C = 0.06 • log 22 0.15 77 77 0.3 rp(n) = 1 100 0.6 n = 0.25541 + 0.83'7) q = d601dl0 SIZE d, = d,o DISTRIBUTION Percent Size VARIABLES 0 +3" K - Hydraulic conductivity (cm/s) g - Acceleration due to gravity @/s2 94 2 Sand Silt v -Viscosity (mm2/s� 4 Clay C - Coefficient — (p(n) - Function of porosity — n - Porosity * — 77 - Uniformity — de - Effective grain diameter (mm) d,o - Diameter at 10% (mm) d60 - Diameter at 60% (mm) * May substitute measured porosity. �` EasySol ve Software LLC WP.O. Box 3247, Eagle, Colorado 81631 lkj www.easysolve.com (970) 319-1591 8/13/2014 Earth Systems Southwest Bermuda Dunes, California Sample ID: DW-I @ 42' Sample Date: August 4, 2014 Interval: 42 HYDRAULIC CONDUCTIVITY CALCULATED FROM SIEVE ANALYSIS SIEVE ANALYSIS BEYER METHOD Percent Diameter K = S C • (p(n)• dz where: g = 9.81 m/s2 0 0.001 v v =1.14 mm 2 /s 4 0.003 K = 7.26E-03 cm/sec 500 8 0.074 C = 0.06 • log 29 0.15 77 82 0.3 (p(n) = l 100 0.6 n=0.255-0+0.831) 77 = d60 Idlo SIZE d, = dto 1 DISTRIBUTION J Percent Size 0 +3" 0 Gravel 92 Sand 4 Silt 4 Clay 1 1 VARIABLES K - Hydraulic conductivity (cm/s) g - Acceleration due to gravity (m/s2 v - Viscosity (mm 2/s) C - Coefficient — rp(n) - Function of porosity — n - Porosity * — 77 - Uniformity — d, - Effective grain diameter (mm) d,o - Diameter at 10% (mm) d60 - Diameter at 60% (mm) * May substitute measured porosity. I EasySolve Software LLC Cn C�P.O. Box 3247, Eagle, Colorado 81631 www.easysolve.com (970) 319-1591 8/ 13/2014 I 1 I I I I 1 Earth Systems Southwest Bermuda Dunes, California Sample ID: DW-I @ 48' Sample Date: August 4, 2014 Interval: 48 HYDRAULIC CONDUCTIVITY CALCULATED FROM SIEVE ANALYSIS SIEVE ANALYSIS BEYER METHOD Percent Diameter K = g C • (p(n) • d z where: g = 9.81 m/s' 0 0.001— v v =1.14 mm2�s 3 0.003 K = 6.05E-03 cm/sec 500 10 0.074 C = 0.06 • log 28 0.15 q 66 0.3 (p(n) = 1 n=0.255•�1+0.83n 197 10.6 .18 77=d601dlo de = d10 SIZE DISTRIBUTION VARIABLES Percent Size K - I lydraulic conductivity (cm/s) g - Acceleration due to gravity m/s2 0 90 Gravel Sand v -Viscosity (mm Z/s� 7 Silt C - Coefficient — 3 Clay �9(n) - Function of porosity — n - Porosity * — q - Uniformity — d, - Effective grain diameter (mm) dlo - Diameter at 10% (mm) d60 - Diameter at 60% (mm) * May substitute measured porosity EasySolve Software LLC wCv' P O. Box 3247, Eagle, Colorado 81631 www.easysolve.com (970) 319-1591 8/13/2014 1 Earth Systems Southwest I Bermuda Dunes, California Sample ID: DW-I @ 52' Sample Date: August 4, 2014 Interval: 52 HYDRAULIC CONDUCTIVITY CALCULATED FROM SIEVE ANALYSIS I SIEVEANALYSIS BEYER METIIOD Percent Diameter K = g C • (p(n) • d 2 where: g = 9.81 m/s' 1 v v = 1.14 mmZls 4 0.003 K = 8.16E-03 cm/sec 500 7 0.074 C = 0.06 • log 63 0.35 (p(n) =1 n=0.255•(1+0.837) 95 10.6 = d60 Idto 100 12.7 de = dlo SIZE DISTRIBUTION VARIABLES K - Hydraulic conductivity (cm/s) 1 Percent Size g - Acceleration due to gravity (m/s2 0 +311 Gravel v -Viscosity �mmZ/s) 1 92 Sand C - Coefficient — 3 Silt (p(n) - Function of porosity — 4 Clay 1 n -Porosity — r/ - Uniformity — d, - Effective grain diameter (mm) d,o - Diameter at 10% (mm) d60 - Diameter at 60% (mm) J* May substitute measured porosity. J J J EasySolve Software LLC P.O. Box 3247, Eagle, Colorado 81631 (� www.easysolve.com (970) 319-1691 8/13/2014 j Earth Systems Southwest Bermuda Dunes, California Sample ID: DW-I @ 54' Sample Date: August 4, 2014 Interval: 54 HYDRAULIC CONDUCTIVITY CALCULATED FROM SIEVE ANALYSIS SIEVEANALYSIS BEYER METHOD Percent Diameter K = S C • rp(n) • d? where: g = 9.81 m/s' v v = 1.14 mm2/s 4 0.003 K = 5.87E-03 cm/sec 500 10 0.074 C = 0.06 • log 28 0.15 77 58 0.3 (p(n) =1 n=0.255•�1 +0.831) 196 ]0.68 77 = d601dlo de = dlo SIZE DISTRIBUTION VARIABLES Percent Size K - Hydraulic conductivity (cm/s) 0 +3" g - Acceleration due to gravity rm/s2 0 90 Gravel Sand v -Viscosity (mm 2/s) 6 Silt C - Coefficient — 4 Clay r+) - Function of porosity — n - Porosity * — 77 - Uniformity — d, - Effective grain diameter (mm) d,o - Diameter at 10% (mm) d60 - Diameter at 60% (mm) * May substitute measured porosity IUJ%.EasySolve Software LLC i P.O. Box 3247, Eagle, Colorado 81631 www.easysolve.com (970) 319-1591 8/13/2014 1 Earth Systems Southwest I Bermuda Dunes, California Sample ID: DW-2 @ 22' Sample Date: August 4, 2014 Interval: 22 HYDRAULIC CONDUCTIVITY CALCULATED FROM SIEVE ANALYSIS SIEVE ANALYSIS BEYER METHOD Percent Diameter K = g • C • (p(n) • d? where: g = 9.81 m/s' 0.001— v v = 1.14 mm��s 50 0.003 K = 7.13E-03 cm/sec 500 8 0.074 C = 0.06 • log 1 24 0.15 77 58 0.3 (p(n) = 1 93 0.6 n = 0.255 - (I + 0.83" 99 1.18 77 = d60I dio 100 2.36 d, = dlo 1 SIZE DISTRIBUTION VARIABLES K - Hydraulic conductivity (cm/s) Percent Size g - Acceleration due to gravity @s2 0 0 +3" Gravel v -Viscosity @mz/s� 1 92 Sand C - Coefficient — 3 Silt (p(n) - Function of porosity — 5 Clay n -Porosity — 77 - Uniformity — de - Effective grain diameter (mm) 1 d,o - Diameter at 10% (mm) d60 - Diameter at 60% (mm) * May substitute measured porosity. _3 J EasySolve Software LLC Vn—�� P O. Box 3247, Eagle, Colorado 81631 www.easysolve.com (970) 319-1691 8/13/2014 Earth Systems Southwest Bermuda Dunes, California Sample ID: DW2 @ 27 feet Sample Date: August 4, 2014 Interval: 27 HYDRAULIC CONDUCTIVITY CALCULATED FROM SIEVE ANALYSIS SIEVEANALYSIS BEYER METHOD Percent Diameter K = S C • (p(n)• de where: g = 9.81 m/s' 0 0.001 v v = l .14 mmz�s 5 0.003 K = 1.86E-03 cm/sec 500 11 0.074 C = 0.06 • log 31 0.15 77 66 0.3 p(n) =1 n=0.255•+0.831) �1 l94 10.6 >7 = d601dlo d, = djo SIZE DISTRIBUTION VARIABLES Percent Size K - Hydraulic conductivity (cm/s) g - Acceleration due to gravity @/s2 0 89 Gravel Sand v -Viscosity (mmZ/s) 6 Silt C - Coefficient — 5 Clay (p(n) - Function of porosity — 17 - Porosity * — 77 - Uniformity — de - Effective grain diameter (mm) d,o - Diameter at 10% (mm) d60 - Diameter at 60% (mm) * May substitute measured porosity Ej EasySolve Software LLC P.O. Box 3247, Eagle, Colorado 81531 www.easysolve.com (970) 319-1591 8/13/2014 Earth Systems Southwest Bermuda Dunes, California Sample ID: DW-2 @ 40' Sample Date: August 4, 2014 Interval: 40 HYDRAULIC CONDUCTIVITY CALCULATED FROM SIEVE ANALYSIS SIEVEANALYSIS BEYER METHOD Percent Diameter K = S • C • (p(n)• d2 where: g = 9.81 m/s2 v v = 1.14 mm2/s 4 0.003 K = 7.26E-03 cm/sec 500 8 0.074 C = 0.06 • log — 28 0.15 77 78 0.3 (p(n) = 1 100 0.6 n = 0.25541 + 0.83"' ) i = d601dto SIZE de = dio DISTRIBUTION Percent Size VARIABLES 0 +3" K - Hydraulic conductivity (cm/s) g - Acceleration due to gravity (m/s2 ) 900 4 Sandel Silt v -Viscosity (in 4 Clay C - Coefficient — rp(n) - Function of porosity — n - Porosity * — q - Uniformity — de - Effective grain diameter (mm) d,o - Diameter at 10% (mm) d60 - Diameter at 60% (mm) * May substitute measured porosity. EasySol ve Software LLC Fcn—W� P.O. Box 3247, Eagle, Colorado 81631 www.easysolve.com (970) 319-1691 8/13/2014 Earth Systems Southwest Bermuda Dunes, California Sample ID: DW-2 @ 42' Sample Date: August 4, 2014 Interval: 42 HYDRAULIC CONDUCTIVITY CALCULATED FROM SIEVE ANALYSIS SIEVE ANALYSIS BEYER METHOD Percent Diameter K = g C • (p(n) • de where: g = 9.81 m/sz v v =1.14 mm2 /s 4 0.003 K = 7.31E-03 cm/sec 500 8 0.074 C = 0.06 • log 25 0.15 77 69 0.3 �9(n) = 100 0.6 n=0.25541+0.83°) 77 = d60 Idlo SIZE do = dio DISTRIBUTION Percent Size VARIABLES 0 +3" K - I lydraulic conductivity (cm/s) g - Acceleration due to gravity @/s2 ) 900 4 Sand Silt v -Viscosity �mm2/ls� 4 Clay C - Coefficient — (p(n) - Function of porosity — n - Porosity * — q - Uniformity — d, - Effectiv e gra in diameter (mm) d,o - Diameter at 10% (mm) d60 - Diameter at 60% (mm) * May substitute measured porosity. MSEasySolve Software LLC P O. Box 3247, Eagle, Colorado 81631 www.easysolve.com (970) 319-1591 8/13/2014