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Home My WebLink AboutCUP 260D; PALOMAR TRANSFER STATION; PERCOLATION TESTING REPORT; 2019-11-01~ll.z, REPUBLIC a.il' - PERCOLATION TESTING REPORT PALOMAR TRANSFER STATION 5960 EL CAMINO REAL CARLSBAD, CALIFORNIA NOVEMBER 2019 PREPARED FOR: Republic Services, Inc. 8514 Mast Blvd Santee, California 92071 PREPARED BY: Geo-Logic Associates 11415 West Bernardo Court, Suite 200 San Diego, California 92127 (858) 451-1136 RECORD COPY Ottt}~3, Initial RECEIVED DEC O 9 2019 LAND DEVELOPMENT ENGINEERING CUP 260(D) Percolation Testing Report, Palomar Transfer Station, Carlsbad, CA 1. INTRODUCTION 1.1 GENERAL This report presents the results of geotechnical investigation, field percolation testing, and geotechnical evaluation of subsurface material to evaluate the feasibility of onsite soil percolation of stormwater at 5960 El Camino Real in Carlsbad, CA, (see Site Plan, Figure 1). This report presents GLA's planning-level geotechnical recommendations for site infiltration. These recommendations are based on subsurface information collected during GLA investigation. The conclusions and recommendations in this report should not be extrapolated to other areas or used for other projects without our review. 1.2 PROJECT UNDERSTANDING GLA understands that the project involves the feasibility of onsite stormwater. Based on conversations with representatives of Republic, shallow percolation beds/trenches or deeper gallery-type vaults may be considered for the northern (re-fueling) parking lot and/or the southern "employee" parking lot. The general site conditions are presented in Figure 1. 1.3 INFORMATION PROVIDED The approximate limits of each parking lot were provided to us by representatives of Republic Services and are approximately shown on Figure 1. 1.4 PURPOSE AND SCOPE OF SERVICES The purpose of this investigation was to evaluate subsurface conditions at the site to develop planning-level geotechnical recommendations for the design of the proposed infiltration facilities. The following work was performed. • Review of information provided by Republic and a site reconnaissance to observe surface site conditions at the locations for each site delineated by Republic. • Utility location clearance by Underground Service Alert (USA) and our third-party geophysical underground utility locating subcontractor (South West Geophysics). • Coordination of our subsurface exploration with onsite representatives of the Transfer Station. • Subsurface exploration by means of two exploratory borings and six in-situ percolation tests, as discussed in Section 2.2 of this report. Obtain representative soil samples from the borings. • Engineering evaluations and preparation of this percolation report. ---------------------·----····' Percolation Testing Report, Palomar Transfer Station, Carlsbad, CA 2. SITE INVESTIGATION 2.1 GENERAL Field investigation consisted of a site reconnaissance (including utility location clearance) and a subsurface exploration. The subsurface exploration is discussed below. The interpretation of encountered subsurface conditions is presented in Section 3.1. 2.2 SUBSURFACE EXPLORATION Our subsurface exploration program included advancement of two borings across the site (B-2 and B-6) for soil sampling and six percolation borings (P-1 through P-6) for the performance of percolation testing. The approximate locations of borings and percolation test holes are shown in Figure 2. The borings were advanced using a truck-mounted drill rig and a 7-inch diameter hollow-stem auger. The borings were advanced from 6 to 20 feet below the existing ground surface. Representative soil samples were recovered by driving a Standard Penetration Test (SPT) soil sampler up to 18 inches into the soil by means of a 140-pound automatic hammer falling 30 inches. The number of blows required to drive the samplers was recorded for each 6-inch penetration interval. The number of blows required to drive the sampler for the last 12 inches of penetration is presented as blows per foot (i.e., blow count) on the borehole log. Visual classification of soil encountered in B-2 and B-6 was performed by our field personnel in accordance with the Unified Soil Classification System (ASTM D 2487 and D 2488). A Key to Soil Classification is included in Appendix A along with the boring logs. The borings were backfilled prior to our representative leaving the site. The percolation test holes were left open overnight and covered with orange construction cones for the required testing pre-soaking. 2.3 GEOTECHNICAL LABORATORY TESTING Geotechnical samples were obtained from the two soil borings on the site. Since the soil conditions are mostly fine-grained clay, geotechnical laboratory tests were not deemed to be necessary at this time, but will be retained for 60 days for future testing, if necessary. Project 5018.1210 November 2019 2 Geo-Logic Associates Percolation Testing Report, Palomar Transfer Station, Carlsbad, CA 3. FINDINGS 3.1 SUBSURFACE CONDITIONS Northern Re-Fueling Parking Lot: Boring B-2 was advanced in the southern portion of the northern parking lot and encountered a surficial layer of 2 to 4 inch diameter gravel underlain by 5 feet of Fill soils consisting of stiff, silty clay with trace of sand and some medium angular to sub-angular to 3 inches in diameter extending to a depth of 5 feet below the existing ground surface. At a depth of 5 feet, the Pt. Loma Formation (Kennedy and Tan, 2005) was encountered to the total depth explored of 20 feet. The Pt. Loma Formation was described as slightly weathered, slightly cemented, grey-brown, sandy to clayey siltstone to silty claystone with iron-staining and caliche stringers. Southern Employee Parking Lot: Boring B-6 was advanced in the southern portion of the southern employee parking lot and encountered a surficial layer of 2 to 4 inch diameter gravel underlain by 3 feet of Fill soils consisting of stiff, silty clay to clayey silt with a trace of fine sand and coarse angular gravel to 2 to 10+ inches in diameter. At a depth of 3 feet, the Lusardi Formation (Kennedy and Tan, 2005) was encountered to the total depth explored of 6 feet. At depth of 6 feet, practical refusal on large boulders was encountered. Three separate attempts were needed to advance the borehole to a depth of 6 feet. The Lusardi Formation was described as slightly weathered, slightly cemented, brown, sandy to silty claystone with angular gravel and cobbles ranging in size from 4 to 12+ inches. Soil Survey: Review of the USDA Web Soil Survey indicates the site is underlain by the Las Flores loamy fine sand generally consisting of a surficial layer (upper 12-14 inches) of loamy fine sand overlying sandy clay to clay. The Hydrological Soil Group is "D" with a capacity to transmit water ranging from very low to moderately low (0.00 to 0.06 inches per hour). Group D soils typically have very slow percolation rates when thoroughly wet. They are clays that have a high shrink-swell potential, soils that have a high permanent water table, soils that have a clay layer at or near the surface, or soils that are shallow over nearly impervious material. The rate of water transmission for group D soils is very slow (San Diego County, 2016). 3.2 GROUNDWATER Groundwater was not encountered at a depth of 20 feet below the existing ground surface in Boring B-2 and at a depth of 6 feet in Boring B-6. Based on boring logs near the site (Geotracker, 2018), groundwater below the site is on the order of 50 + feet below the ground surface across the site. 3.3 VARIATIONS IN SUBSURFACE CONDITIONS Our interpretations of subsurface and groundwater conditions, as described in this report, are based on data obtained from this investigation. Our conclusions and geotechnical recommendations are based on interpretation of this data. Careful observations should be made during construction to verify our interpretation. Should variations from our interpretations be found, GLA should be notified to evaluate whether any revisions should be made to the recommendations herein. Project 5018.1210 November 2019 3 Geo-Logic Associates Percolation Testing Report, Palomar Transfer Station, Carlsbad, CA 4. PERCOLATION TESTING 4.1 SOIL PERCOLATION TESTING Six borings were advanced to facilitate percolation testing in the approximate locations and depths directed by representatives of site, our experience with similar sites, and vehicle/underground utility constraints to estimate the infiltration rate across the two parking lots at various depths. The borings were advanced on November 9, 2018 and the percolation testing was performed on November 10, 2018 after the required pre-soaking due to clayey soils. The approximate locations of the percolation tests (P-1 through P-6) are presented on Figure 2. The conditions encountered at each of the testing locations follow: Table 1-Percolation Test Summary Test Soil Conditions Encountered as Measured Below Existing Depth to Bottom of Percolation Test From Number Ground Surface, ft Existing Ground Surface, ft P-1 Stiff, dry to moist, silty clay with some fine sand and small 4.0' gravel to 3 inches in diameter, moderately plastic (CL) P-2 Stiff, dry to moist, silty clay with trace fine sand and small 3.0' gravel to 2 inches in diameter, moderately plastic (CL) P-3 Stiff, dry to moist, silty clay with trace fine sand and small 5.0' gravel to 2 inches in diameter, moderately plastic (CL) P-4 Stiff, dry to moist, silty clay with trace fine sand and small 3.0' gravel to 3 inches in diameter, moderately plastic (CL) P-5 Medium stiff to stiff, dry, clayey silt with trace of sand and 3.0' gravel to 4+ inches in diameter (ML) P-6 Medium stiff to stiff, dry, clayey silt with some fine to 4.0' coarse sand and gravel to 8+ inches in diameter (ML) Note: Depth measured below existing ground surface. Percolation testing was performed in all six percolation borings in accordance with the recommendations set forth by the County of San Diego "Model BMP Design Manual, San Diego Region", dated February 2016, Appendix C and D using the borehole percolation test method (as described in Appendix D, Section D.3.3.2). A reduction factor was applied to the field percolation rate to calculate the raw (vertical) infiltration rate which is corrected for non-vertical flow in accordance with the procedures described in the "County of Los Angeles Department of Public Works, Geotechnical and Materials Engineering Division, Guidelines for Geotechnical Investigation and Reporting, Low Impact Development Stormwater Infiltration, Administrative Manual GS200.2", dated 6/30/17, Page 9 of 17. Project 5018.1210 November 2019 4 Geo-Logic Associates Percolation Testing Report, Palomar Transfer Station, Carlsbad, CA The raw (vertical) infiltration rates are reported for each test location in the table below. The raw infiltration rate is converted into the Design Infiltration Rate using an applied safety factor of 4 (to account for "site suitability" and system "design" in accordance with Appendix D, Worksheet D.5-1 of the "San Diego County Model BMP Design Manual") in the table below. Table 2 -Design Infiltration Rates from Percolation Testing Percolation Test Raw Vertical Infiltration Rate, Design Infiltration Rate (with Safety Number (Figure 2) (inches/hour) Factor=4), (inches/hour) P-1 0.47 0.1 P-2 0.04 0.01 P-3 0.019 0.005 P-4 0.03 0.008 P-5 0.3 0.07 P-6 0.4 0.1 Note: Depth measured below existing ground surface, safety factor from Form 1-9. The results of the percolation testing across the site indicate that the upper five feet (below existing grades) is comprised of clayey silt to silty clay soils above the weathered bedrock for both the north (re-fueling) parking lot and the south (employee) parking lot. The boring on the north parking lot (B-2) encountered Pt. Loma/Santiago Formation comprised of sandy to silty claystone with gravel at a depth of 5 feet below the existing ground surface. The boring on the south parking lot (B-6) encountered Lusardi Formation comprised of sandy to silty claystone and clayey siltstone at a depth of 3 feet below the existing ground surface. Practical drilling refusal was encountered in Boring B-6 at a depth of 6 feet below the existing ground surface. Since the County of San Diego Low Impact Development Handbook, 2014 (Appendix A, Table A.1-1) recommends underdrains in areas where the design infiltration rate is less than 0.5 inches per hour, the test results indicate that all the six tested locations (P-1 through P-6) are not suitable for direct onsite water infiltration. Additional design guidelines for infiltration feasibility (San Diego, 2016) are presented below: • The ability to infiltrate stormwater is limited in areas with a high groundwater table. A 10- foot separation distance is required from the bottom of the infiltration facility to the seasonal high groundwater level. • Native soils that are Hydrologic Soil Group (HSG) A or B are suitable for infiltration without amendments. Other concerns with regard to infiltration of stormwater to soils are the potential for liquefaction during earthquakes, expansion of clay soils, or compression of fill or alluvium. All of these conditions can cause damage to structures and pavements. • Stormwater infiltration is not recommended on hillsides (slopes of 20 percent or more) because of the risk of downhill seepage that creates surficial slope instability (increased potential of erosion, slumps, or slides). Project 5018.1210 November 2019 5 --------------·-· . Geo-Logic Associates Percolation Testing Report, Palomar Transfer Station, Carlsbad, CA • Stormwater should not be infiltrated in areas adjacent to improvements that could be damaged by the presence of groundwater. Infiltration facilities should be set back 10-25 feet from building foundations, basements, footings, and retaining walls to prevent the zone of saturation from undermining structures. • Infiltration is not appropriate within 100 feet of water supply wells. • Infiltrating practices might also be restricted in stormwater hotspots such as industrial and high-traffic. Infiltration (San Diego, 2016) is typically not permitted if: • Soil contamination is expected or is present. • Runoff could unintentionally be received from a stormwater hotspot. • The groundwater table is within 10 feet of the proposed subgrade. • The site is within 100 feet of a water supply well or septic drain field. • The site is within 10 feet of a structure or foundation. • Infiltrated water could interfere with utilities. • Underlying geology presents risks for sinkholes or liquefaction. • The site is within 50 feet of a steep, sensitive slope. Project SO18.1210 November 2019 6 Geo-Logic Associates Percolation Testing Report, Palomar Transfer Station, Carlsbad, CA 5. CONCLUSIONS Based on the very poor site infiltration rates and considering the shallow depth to dense, relatively impermeable formational materials across both the north and south parking areas, it appears that the use of this site for onsite stormwater infiltration into the (un-amended) onsite clayey soils is relatively impractical. See County of San Diego Form 1-8 in Appendix C for more information. Project SO18.1210 November 2019 7 Geo-Logic Associates Percolation Testing Report, Palomar Transfer Station, Carlsbad, CA 6. LIMITATIONS In preparing the findings and professional opinions presented in this report, Geo-Logic Associates (GLA) has endeavored to follow generally accepted principles and practices of the engineering geologic and geotechnical engineering professions in the area and at the time our services were performed. No warranty, express or implied, is provided. The conclusions and recommendations contained in this report are based, in part, on information that has been provided to us. In the event that the general development concept or general location are modified, our conclusions and recommendations shall not be considered valid unless we are retained to review such changes and to make any necessary additions or changes to our recommendations. Subsurface exploration is necessarily confined to selected locations and conditions may, and often do, vary between these locations. Should conditions different from those described in this report be encountered during project development, GLA should be consulted to review the conditions and determine whether our recommendations are still valid. Additional exploration, testing, and analysis may be required for such evaluation. Should persons concerned with this project observe geotechnical features or conditions at the site or surrounding areas which are different from those described in this report, those observations should be reported immediately to GLA for evaluation. It is important that the information in this report be made known to the design professionals involved with the project, that our recommendations be incorporated into project drawings and documents, and that the recommendations be carried out during construction by the contractor and subcontractors. It is not the responsibility of GLA to notify the design professionals and the project contractors and subcontractors. The findings, conclusions and recommendations presented in this report are applicable only to the specific project development on this specific site. These data should not be used for other projects, sites or purposes unless they are reviewed by GLA or a qualified geotechnical professional. Report prepared by, Geo-Logic Associates Jose G. F~ ervising Geotechnical Engineer REAR OF TEXT Vicinity Map Figure 1 Figure 2 Appendix A Appendix B Boring/Percolation Testing Location Map Boring Logs County of San Diego Forms 1-8 and 1-9 Project 5018.1210 November 2019 8 Geo-Logic Associates Percolation Testing Report, Palomar Transfer Station, Carlsbad, CA 7. REFERENCES Cal Vada Surveying, 2016, Topographic Survey, 5960 El Camino Real, Carlsbad, CA, 4 Sheets, dated March 23, 2016. County of Los Angeles, Department of Public Works, 2014, GS200.1, Administrative Manual, Geotechnical and Materials Engineering Division Guidelines for Design, Investigation, and Reporting Low Impact Development Stormwater Infiltration, dated June 2014. County of Los Angeles, Department of Public Works, 2011, GS200.1, Administrative Manual, Geotechnical and Materials Engineering Division, Low Impact Development Best Management Practice Guideline For Design, Investigation, and Reporting, dated June 2011 Geotracker, 2018, State of California Water Resources Control Board website: https:// geotracker. waterboards.ca.gov / Kennedy, M. P. and Siang S. Tan, 2005, Geologic Map of the Oceanside 30' X 60' Quadrangle, California, Compiled by: Kelly R. Bovard, Rachel M. Alvarez and Michael J. Watson Los Angeles County, 2009, Low Impact Development Standards Manual, dated January 2009. Los Angeles County, Department of Public Works, Geotechnical and Materials Engineering Division, Guidelines for Geotechnical Investigation and Reporting, Low Impact Development Stormwater Infiltration, Administrative Manual GS200.2, dated 6/30/17. Peabody, A.W., 2001, Control of Pipeline Corrosion, NACE International-The Corrosion Society, edited by Ronald Bianchetti. San Diego County, 2016, County of San Diego Model BMP Design Manual San Diego Region, February 2016. San Diego County, 2014, County of San Diego Low Impact Development Handbook, July 2014. USDA, 2018, We Soil Survey, https://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx Project SO18.1210 November 2019 9 Geo-Logic Associates lj ~ IJ j fill .... t I :<l ~ j t : ~I ~ ~I ii ~I i ll ii s■ - ~~ ... --n:.o.•-,-.;;;;,.~·-_,,...,,,...~ EXPLANATION SPIUKIT ORAINAGE FLOW OIRECTION STORM ORAIN INLET TRENCH ORAIN -------CURB ----STORM ORAIN PIPE -• • • • • • -OVERFLOW TRENCH DRAIN .,,._,,__,, ORAINAGE AREA -NON-INDUSTRIAL DISCHARGE AREAS ~ IMPERVIOUS AREA SW-1 ♦ SAMPLE LOCATION -FENCE PROPERTY BOUNDARY (((((((((((( DRAINAGE DITCH ccaxxxxxax, STRAWWATTLE ~WINDFENCE • ORAINAGE AREA DISCHARGE LOCATION i§],_:_ ~-~·- Caldwell. i PALOMAR TRANSFER STATION 5960 EL CAMINO REAL CARLSBAD, CALIFORNIA Reference: Google Earth. 2018. 8-6 0 Approximate Location of Exploratory Boring LEGEND Geo-Loaic AISOCIATis::J Draft JGF Date NOV 2018 Protect No ,s 1201 00 P-6 ■ Approximate Location of Percolation Test BORING/PERCOLATION TEST LOCATION MAP PALOMAR TRANSFER STATION, CARLSBAD, CA FIGURE 2 Percolation Testing Report, Palomar Transfer Station, Carlsbad, CA APPENDIX A BORING LOGS Geo-Logic Associates Highlv Omanlc Soils . Silts and Chlw Liquid Limit >50% UNIFIED SOIL CLASSIFICATION mo o. 200 sieve ~ 0 ~ 40----+-t--+-..-f---+--+---l~+--+--t ~ 0 ~ 52111---1---,1.~....g~~-l--'--+~I--I Q. LABORATORY CLASSIFICATION CRITERIA GW and SW: Cu = D90 /010 greater lhan 4 for GW, greater lhan 6 for SW Cc = c.,,,2/D'° x D10 between 1 and 3 GP and SP: Clean gravel or sand not meeting requirements for GW and SW GM and SM: Atterberg Limits below "A" LINE and Pl less lhan 4 GC and SC: Atterberg Limits above "A" LINE and Pl greater than 7 Fine Medium Coarse Fine Sand Sand Sand Gravel Boulder Classification of ,arth materials is b45ed on field lns~ction and should not be construed to impiy laboratory analysts unless so stated MATERIAL SYMBOLS CONSISTENCY CLASSIFICATION FOR SOILS ~ ~ [IJ ~ ~ § ~ m § Asphalt Concrete Conglomerate Sandstone Silty Sandstone Clayey Sandstone Siltstone Sandy Siltstone ClaYell Siltstone ,~1ny Claystone Claystone/Shale ~ ~ ~ § ~ m -m3 Calcaerous Sandstone Marl Limestone Dolostone Breccia Volcanic Ash/Tuff Metamorphic Rock Quartzite Extrusive Igneous R Intrusive Igneous R Accordina to the Standard Penetration Test Blows / Foot* Granular Blows / Foot* Cohesive 0-5 Very Loose 0-2 Very Soft 6-10 Loose 2-4 Soft 11 -30 Medium Dense 4-8 Medium Stiff 31-50 Dense 8-15 Stiff 50 Very Dense 15-30 Very Stiff >30 Hard • using 140-lb. hammer with 30• drop "" 350 ft-lb/blow LEGEND OF BORING Bulk Sample Driven Samp Water Level 'Sl.. "NSR" indicates NO SAMPLE RECOVERY JOB NO.: SITE LOCATION: S018.1210.00 Geo-Logic Associates Boring Log PALOMAR TRANSFER STATION BORING NO.: 8-2 PAGE: 1 OF 1 GW DEPTH: N/ A CAVING DEPTH: N/A DRIWNG METHOD: J9 f HOLLOW STEM AUGER DATE STARTED: 11/9/2018 DATE FINISHED: 11/9/2018 ELEVATION: 313 FT MSL {CAL VADA. 2016) LATITUDE: 33.135438' TOTAL DEPTH: 20 FEET NOTES: 140 POUND AUTO-HAMMER (!) 0~ CL~ 0:: CONTRACTOR: PACIFIC DRIWNG LOGGED BY: JGF ~t;:' ~~ E'::--:-........ LJJ d LJJ ~t N,-.. V) t: 0:: iii ~ z ~iii z . ~g LJJ 01!! LJJ ::, 9 !z '!I :I: 0~ ....I ~-0.. 0 0.. 0..0 ~~ 0 ID :::> ~5 ::I: ~ 0 0 ~ ::I: 0 ~ 0 ....... - 10 1.4 25 1.4 2 22 1.4 3 12 1.4 4 15 1.4 5 - ;JI, LONGITUDE: 117 .267813" -,_ .... ..... ......... ,_ ......... '-1 ..... 1-,_ -......... ..... '-2 -..... ..... ---,_ 3 ..... .... ,_ ..... --.__ 1-4 ......... - .......... -1-5 .__ --..._ ---~I: ..._ -----_ ..... '-7 --- ----8 -------'-'-9 ,-'- '- '-,- '-'-'-10 '-'-._ ,-'-.... ,_ '-'-15 .... .......... .......... --16 --~ '== =-= .__:.= =-= _:.= .__ :.= =-= -:.= == == .__ :.= =-= =-= =-= =-= == == =-= -_-, VISUAL FIELD DESCRIPTION CL FILL: 2 TO 4 INCHES OF CRUSHED GRAVEL, OVER BROWN, DRY TO SLIGHTLY MOIST, STIFF, SILTY CLAY WITH TRACE OF FINE SAND, ROOTLETS, SOME MEDIUM ANGULAR TO SUB-ANGULAR GRAVEL TO 3 INCHES IN DIAMETER. PT. LOMA FORMATION: GRAY-BROWN, MOIST, SANDY TO CLAYEY SILTSTONE TO SILTY CLAYSTONE, IRON-STAINED, CALICHE STRINGERS, MODERATELY WEATHERED, SLIGHTLY CEMENTED. 12 INCH VOID ENCOUNTERED IN FORMATION AT 15.5 FEET • NOTES: 1. TOTAL DEPTH = 20 FEET. 2. NO GROUNDWATER ENCOUNTERED AT TIME OF DRILLING. 3. NO CAVING DURING DRILLING. 4. BORING BACKFILLED WITH BORING CUTTINGS ON 11 /9 / 18. The data presented on this log is a simplification of actual conditions encountered and applies only at the location of this boring and at the time of drilling. Subsurface conditions may differ at other locations and may change with the passage of time. JOB NO.: SITE LOCATION: S018.1210.00 Geo-Logic Associates Boring Log PALOMAR TRANSFER STATION BORING NO.: 8-6 PAGE: 1 OF 1 DRIWNG METHOD: 7" I HOLLOW STEM AUGER DATE STARTED: 11/9/2018 DATE FINISHED: 11/9/2018 ELEVATION: 304.5 FT MSL {CAL VADA, 2016) LATITUDE: 33.134696" GW DEPTH: N/A CAVING DEPTH: N/A TOTAL DEPTH: 6 FEET (!) 0~ il:~ 0:: CONTRACTOR: PACIFIC DRIWNG LOGGED BY: JGF ~ ~~ e:::--:-w 1/l l:i: 0:: ~~ v,-z . ~g !t2 (/) w:::, ~~ 0~ a..O ~~ 0 i5 0 N~ ::::E a.. 0 ........ ........ ~t g !z m ::> 0 u ........ 10 100+ w N...--. vi ~ ~ ::i:: a.. u ~5 1.4 1.4 0 z w ..J a.. ::::E i7i 2 LONGITUDE: 117 .267 485° NOTES: 140 POUND AUTO-HAMMER i!:t:i a..lJJ WLL.. VISUAL FIELD DESCRIPTION 0 ,_ '--DARK BROWN, DRY TO SLIGHTLY MOIST, STIFF, SILTY CLAY TO CLAYEY SILT, WITH TRACE OF FINE SAND, SOME MEDIUM TO ::_, =:: COARSE ANGULAR GRAVEL TO 2 TO 1 O+ INCHES IN -= [L FILL: 2 TO 4 INCHES OF CRUSHED GRAVEL, OVER '---._ -DIAMETER. !,_ ........ ::, ~ ........ L=u""SAR=D1'""F'-O-R_MA_JI_O_N_: _B_R_O-WN-,-M-0-IST-, _HAR_D_SAN_D_Y_T_O-SI-LTY----1 CLAYSTONE WITH ANGULAR GRAVEL TO 1 INCH IN SAMPLER, SLIGHTLY WEATHERED, SLIGHTLY CEMENTED, COBBLES FROM 4 TO 12+ INCHES IN DIAMETER. PRACTICAL DRIWNG REFUSAL ON LARGE ROCK AT 6 FEET. --2 ..... _ ..... --,__ h 3 -'---.......... -..... _ -4 ,_- '-- 1. ..... ---5 -..... -,_ - '--- 2( .... -6 - '----,__ ,---7 -.... _ 2 ... -.. ........ 9 .... .......... ,_ ,_ .,_ 10 ,>;: -,_ .. .............. ,, ,_'- '-..... ......... ..... -'-14 '-........ \ V NOTES: 1. TOTAL DEPTH = 6 FEET, PRACTICAL DRIWNG REFUSAL AUGER GRINDING ON LARGE ROCKS IN FIRST TWO ATTEMPTS TO ADVANCE HOLE AT FIRST TWO LOCATIONS. 2. NO GROUNDWATER ENCOUNTERED AT TIME OF DRILLING. 3. NO CAVING DURING DRIWNG • 4. BORING BACKFILLED WITH BORING CUTTINGS ON 11/9/18. The data presented on this log is a simplification of actual conditions encountered and applies only at the location of this boring and at the time of drilling. Subsurface conditions may differ at other locations and may change with the passage of time. Percolation Testing Report, Palomar Transfer Station, Carlsbad, CA APPENDIX B CATEGORIZATION OF INFILTRATION FEASIBILITY CONDITION (FORM 1-8) AND SAFETY FACTOR CALCULATION (FORM 1-9) Geo-Logic Associates Appendix I : Forms and Ch ecklists Categorization of Infiltration Feasibility Form 1-8 Condition Part 1 -Fun Infiltration Feasibility Screeoine Criteria Would infiltration of the full design volume be feasible from a physicaJ perspective without any undesirable consequences that cannot be reasonably mitigated? Criteria Screening Question Is the estimated reliable infiltration rate below proposed facility locations greater than 0.5 inches per hour? The response to this Screening Question shall be based on a comprehensi,·e evaluation of the factors presented in 1\ppendix C.2 and .Appendix D. Provide basis: Yes No X Six percolation tests were completed across the site. The calculated infiltration rates (with an applied factor of safety of 4) ranged from 0.005 to 0.1 inches per hour. The results of the testing indicate that full on-site percolation of storm water is not feasible. Please note: although the infiltration rates referenced are of nearby areas, the results may apply to the proposed BMP site locations based on the comprehensive geotechnical evaluation. Summarize fmdings of studies; proVJde reference to studies, calculaaons, maps, data sources, etc. Provide narrallve discussion of study/ data source applicability. 2 Can inJiltradtlo greater than 0.5 inches per hour be allowed without increasing risk of geotechnical hazards (slope stability, groundwater mounding, utilities, or other factors) that cannot be mitigated to an acceptable level? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in .t\ppendi.x C.2. Provide basis: X Infiltration galleries in the site soils would likely cause groundwater mounding and/or surface seepage causing other geotechnical issues and site erosion. Based on the comprehensive geotechnical evaluation, full site infiltration is not feasible due to the nature of the site soils and the relatively low infiltration rates encountered in our testing. Summarize findings of studies; provide reference to studies, calculations, maps, data sotl!ces, etc. Provide narrative discussion of study/dara source applicability. 1-3 February 2016 Appendix I: Forms and Checklists Criteri a 3 Form 1-8 Page 2 of 4 Screening Question Can infiltration greater than 0.5 inches per hour be allowed without increasing risk of groundwater contamination (shallow water table, storm water pollutants or other factors) that cannot be mitigated to an acceptable level? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: Yes No X Infiltration rates greater than 0.5 inches per hour cannot be accomplished on this site and therefore, the question is hypothetical. However, since there is no shallow groundwater table at the site, the risk of groundwater contamination is low. Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of sn1dy/data source applicability. 4 Can in.filtration greater than 0.5 inches per hour be allowed without causing potential water balance issues such as change of seasonality of ephemeral streams or increased discharge of contaminated groundwater to surface waters? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in .Appendix C.3. X Provide basis: Infiltration rates greater than 0.5 inches per hour cannot be accomplished on this site and therefore, the question is hypothetical. However, infiltration at the site is not anticipated to cause potential water balance issues and not anticipated to change the seasonality of ephemeral streams since there are no ephemeral streams in the site area. Summarize findings of studies; provide reference to studies, calculations, maps, data sources, ere. Provide narrative discussion of study/ data source applicability. Part 1 Result * If all answers to rows 1 -4 are "Yes" a full infiltration design is potentially feasible. The feasibility screening category is Full In.filtration If any answer &om row 1-4 is "No", infiltration may be possible to some exrenr but would not generally be feasible or desirable to achieve a "full infiltration" design. Proceed to Part 2 No full infiltration t'fo be completed using gathered sire information and best professional judgment considering the definition of MEP in the MS4 Permit. ,s\dditional resting and/ or studies may be required by the City to substantiate findings. 1-4 February 2016 Appendix I: Forms and Checklists Form 1-8 Page 3 of 4 Part 2 -Partial Infiltration vs. No Infiltration Feasibility Screening Criteria Would infiltration of water in any appreciable amount be physically feasible without any negative consequences that cannot be reasonably mitigated? Criteria 5 Screening Question Do soil and geologic conditions allow for infiltration in any appreciable rate or volume? The response to dus Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2 and Appendix D . Provide basis: Yes No X According to Appendix C the lower limit of partial infiltration is 0.05 inches/hour. The average of the infiltration rates determined by testing on the site is less than 0.05 inches per hour, therefore partial infiltration is not considered feasible. Please note: although the infiltration rates referenced are of nearby areas, the results may apply to the proposed BMP site locations based on the comprehensive geotechnical evaluation. Summarize findings of studies; provide reference to smdies, calculations, maps, data sources, etc. Provide narrative discussion of srudy/data source applicability and why it was not feasible to nutigate low infiltration rates. 6 Can Infiltration in any appreciable quantity be allowed without increasing risk of geotechnical hazards (slope stability, groundwater mounding, utilities, or other factors) that cannot be mitigated to an acceptable level? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2. Provide basis: X Infiltration rates greater than 0.05 inches per hour cannot be accomplished on this site and such, the question is hypothetical. As such, partial infiltration into the site soils will likely cause local groundwater mounding and may daylight as seepage causing other geotechnical concerns and site erosion. Based on the comprehensive geotechnical evaluation, partial infiltration is not feasible due to the nature of the site soils and the relatively low infiltration rates encountered in our testing. Swnmarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/ data source applicability and why it was not feasible to nutigate low infiltration rates. 1-5 February 2016 Criteria 7 Appendix I: Forms and Checklists Form 1-8 Page 4 of 4 Screening Question Can Infiltration in any appreciable quantity be allowed without posing significant risk for groundwater related concerns (shallow water table, storm water pollutants or other factors)? The response to this Screening Q uestion shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. Yes No X Provide basis: Infiltration rates greater than 0.05 inches per hour cannot be accomplished on this site and therefore, the question is hypothetical. However, since there is no shallow groundwater table at the site, the risk of groundwater contamination from partial infiltration is low. Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/ data source applicabilit)' and w:hy it was not feasible to mitigate low infiltration rates. 8 Can infiltration be allowed without violating downstream water rights? The response ro this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. X Provide basis: Infiltration at the site is not recommended due to the low infiltration rates. If allowed, partial infiltration is not anticipated to change the seasonality of ephemeral streams since there are no ephemeral streams in the site area. Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/ data source applicability and why it was not feasible to mitigate low infiltration rates. Part 2 Result* lf all answers from row 5-8 are yes then partial infiltration design is potentially feasible. The feasibility screening category is Partial Infiltration. No infiltration is If any answer from row 5-8 is no, then infiltration of any volume is considered to be recommended infeasible within the drainage area. The feasibility screening category isl No Infiltration.I .,.To be completed usmg gathered slte information and best professional Judgment considering the definit:1011 of MEP 111 the MS4 Permit. 1\dditional resting and/or studies may be required by the City to substantiate findings. Joseph Franzone Digitally signed by Joseph Franzone ON· en-Joseph Franzone o-Geo-1 ogic Associates, ou=San Diego Office, email=jfr!~zonr@geo-logic.com, c=US February 2016 Date: 20 19.11 .07 13:44:36 -08'00' .. Appendix I: Forms and Checklists Factor of Safety and Design Infiltration Rate Worksheet Form 1-9 Factoc Category Factor Description Assigned Factor Product (p) Weight (w) Value (v) p =wxv Soil assessment methods 0.25 2 0.5 Predominant soil texture 0.25 2 0.5 Sui ta bili ry Sire soil variability 0.25 2 0.5 _-\ • -\ssessmcn t Depth to groundwater I impervious 0.25 2 0.5 layer Suitability Assessment Safe1y Factor, S.\ = t p 2.0 Level of pretreatmen t/ expected 0.5 sediment loads 2 1 B Design Redundancy/ resiliency 0.25 2 0.5 Compaction during constroction 0.25 2 0.5 Design Safety Factor, So = Ep 2.0 Combined Safety Factor, S,0,a1= S,\ x Sa 4.0 Observed Infiltration Rate, inch/hr, K,b,eneJ (corrected for rest-specific bias) see table in text Design Infiltration Rate, in/hr, K.ie.,811 = K.Jb,erv<'I / Sroral see table in text Supporting Data Briefly describe infiltration rest and provide reference to rest forms: Testing performed in accordance with San Diego County Guidelines, all holes were pre-soaked overnight with testing performed on second day. Reference: San Diego County, 2016, County of San Diego Model BMP Design Manual San Diego Region, February 2016, Appendix I. 1-31 February 2016