Results of Onsite Percolation Testing Ellis Commons Senior Housing Development APN City of Perris, California

Transcription

1 Lansing Companies High Bluff Drive, Suite 150 San Diego, California April 18, 2017 Project No Attention: Subject: References: Mr. Casey Malone Results of Onsite Percolation Testing Ellis Commons Senior Housing Development APN City of Perris, California Riverside County Flood Control District, Design Handbook for Low Impact Development Best Management Practices, dated September Lansing Companies, 2016, Preliminary Project Plan, 4 AC Perris Ellis Commons, Senior Housing Development, dated December 16, 2016, 30-scale, 1 sheet. In accordance with your request and authorization, Leighton and Associates, Inc. (Leighton) is pleased to present this percolation testing report for the proposed storm water basins located within the proposed Ellis Commons development in Perris, California. The proposed residential development (APN ) is located on the southwest corner of Ellis Avenue and A Street in the City of Perris, California (See Figure 1, Site Location Map). PURPOSE AND SCOPE OF WORK The purpose of our testing was to determine general infiltration rates of onsite soils, depth to bedrock and/or groundwater with respect to two proposed storm water quality basin locations as depicted on the referenced plan. Services provided for this study consisted of the following: Drilling, sampling and logging of 2 exploratory deep borings, one in each area of the proposed storm water basins; Field testing of percolation tests in general accordance with the procedures outlined in the above referenced County Design Handbook; and Compilation of this report that presents the results of our percolation/infiltration testing and laboratory test results.

2 Results of Onsite Percolation Testing April 18, 2017 Ellis Commons Senior Housing Development APN , City of Perris, California Project No SITE DESCRIPTION The project site is located northwest of Ellis Road and A Street in the City of Perris, California. The site is approximately 4.2 Acres of vacant land (APN ). The proposed project will consist of 162 senior housing units varying in size from 500 square feet (sf) to 729 sf, a recreation center, covered parking stalls, two water quality basins and associated landscaping and driveways. The western portion of the project site is underlain by granitic bedrock. The eastern portion, including the proposed water quality basins is underlain by dense older alluvium over granitic bedrock. Depth to bedrock was measured to be about 4.5 and 7 feet at the locations of the proposed northeast and central water quality basins, respectively. Grading plans were not available for our review; however, it is anticipated that cuts and fills up to 20 feet will be required to achieve design grades across the site. We anticipate that grade changes will be minimal at the locations of the proposed water quality basins. SUBSURFACE INVESTIGATION Our field investigation consisted of excavating 2 deep exploratory borings up to 20.5 feet deep and 4 percolation test holes (3 to 5 feet deep) on April 6, The borings and test holes were excavated utilizing a truck mounted CME 75 drill rig equipped with an 8-inch-diameter hollow-stem auger. The exploratory borings were continuously logged to a depth of deeper than 10 feet below bottom of the proposed basin. An engineer from our office logged and observed all excavations. The locations of the exploratory boring and percolation test holes are shown on Plate 1. The logs of the exploratory borings and percolation test holes are included in Appendix A. SOIL AND GROUNDWATER CONDITIONS Based on the results of this study, the locations of the proposed water quality basins are underlain by up to 7 feet of older alluvial soil over granitic bedrock. The deepest depth to granitic bedrock encountered during our field exploration at this site is 9 feet at the location of LB-5 in the north-central portion of the site where artificial fill soil was encountered above the granitic rock. The encountered older alluvium is classified as medium dense to dense, silty sand (SM). Groundwater was not encountered to the depth explored of 20.5 feet. Groundwater was encountered at a depth of 39.5 feet within another boring excavated in the southeast corner of the property. -2-

3 Results of Onsite Percolation Testing April 18, 2017 Ellis Commons Senior Housing Development APN , City of Perris, California Project No PERCOLATION TEST RESULTS Percolation tests were performed at the corresponding depths shown in the table below. Percolation tests were performed in accordance with the procedures of Appendix A, Section 2.3 of the Riverside County Design Handbook referenced above. Results reported below are the most conservative reading in minutes per inch drop and converted to inches per hour per the Porchet method. Field test data are included in Appendix A. Summary of Percolation/Infiltration Test Results Test Hole # Ex. Ground Surface Elev. (ft) Depth BGS (ft) Percolation Rate (min/in) Infiltration Rate (in/hr) Soil Description/Notes P P P P N/A 0.00 Silty Sand (SM) Quaternary Alluvium Silty Sand (SM) Quaternary Alluvium Silty Sand (SM) Quaternary Alluvium Silty Sand (SM) Quaternary Alluvium over Granitic Rock CONCLUSIONS AND RECOMMENDATIONS For preliminary design purposes, an infiltration rate of 0.08 in/hr may be used for the portions of the basins excavated within alluvial sand deposits and where a minimum of 5 feet of permeable soil exists below the basin bottom. Based on our percolation testing, the weathered, surficial granitic rock should be considered impermeable. Current project design indicates that the basins will be excavated within alluvial soil where granitic bedrock is anticipated within 5 feet of the basin bottom. No percolation should be assumed for these design conditions. Based on current design configuration, we recommend that detention basins be considered instead of infiltration basins. Other design alternatives may be possible as well, but would likely require additional testing to determine feasibility at this site. Leighton should be contacted to discuss other design alternatives, if desired. -3-

4 Results of Onsite Percolation Testing April 18, 2017 Ellis Commons Senior Housing Development APN , City of Perris, California Project No LIMITATIONS The above findings and recommendations are based on a general interpretation of soil conditions between test locations, utilizing contemporary engineering principles and practice. We make no other warranty, either expressed or implied. Please notify the engineer in the event conditions are encountered that are not reflected in this report. If you have any question, please do not hesitate to contact this office. We appreciate this opportunity to be of service. Respectfully submitted, LEIGHTON AND ASSOCIATES, INC. Kenneth E. Cox, GE 2793 Senior Project Engineer Robert F. Riha, CEG 1921 Vice President / Senior Principal Geologist Attachments: Figure 1 Site Location Map Plate 1 Field Exploration Plan Appendix A Percolation Data Sheets Log of Exploratory Borings Distribution: (1) addressee (PDF copy via ) -4-

5 Approximate Site Boundary ³ 0 2,000 4,000 Project: Scale: 1 " = 2,000 ' Base Map: Bing Maps 2017 Feet Thematic Information: Leighton Author: (mmurphy) Eng/Geol: SIS/RFR Date: April 2017 Map Saved as P:\Drafting\11607\001\Maps\ _F01_SLM_ mxd on 4/4/2017 9:41:29 AM SITE LOCATION MAP Perris Ellis Commons Senior Apartment Project NWC "A" streeet and Ellis Avenue Perris California Figure 1 Leighton

6 Legend LB-4 < P-4 ( Approximate Location of Auger Boring Approximate Location of Percolation/Infiltration Tests Property Boundary ( P-2 ( P-4 < LB-4 < LB-3 ( P-1 ( P-3 0 ³ Feet Project: Eng/Geol: SIS/RFR Scale: 1 " = 60 ' Date: April 2017 Reference: Plan by MLP Consultants for 4 AC Perris - Ellis Commons Senior Housing Development, December 16, Author: (mmurphy) Map S aved as V:\Drafting\11607\001\Maps\ _F03_FE M_ mxd on 4/11/2017 9:50:26 AM FIELD EXPLORATION PLAN Perris Ellis Commons Senior Apartment Project NWC "A" streeet and Ellis Avenue Perris California Plate 1 Leighton

7 Results of Onsite Percolation Testing April 18, 2017 Ellis Commons Senior Housing Development APN , City of Perris, California Project No APPENDIX A Percolation Data Sheets Log of Exploratory Borings

8 Test Hole Number: P-1 Project Perris Ellis Commons Date Excavated: 4/6/2017 Project Number Tested by: BSS Date Tested 4/7/2017 Soil Unit: Qal Depth of Test Hole (in.) USCS Soil Type: SM Diameter (in.) 8 Effective Radius (in) 3.5 t Total Initial Water Depth Final Water Depth Change In Water Level Infiltration Rate* (inches/hour) Peroclation Rate (minute/inch) 10:30:00 10:40:00 10:41:00 10:51:00 10:52:00 11:22:00 11:25:00 11:55:00 11:56:00 12:26:00 12:28:00 12:58:00 12:59:00 13:29:00 13:30:00 14:00: Infiltration Rate (in./hr) * Based on Porchet Method Percolation Project Number: Test Data Project Name: Perris Ellis Commons P-1 Date: Apr-17 Leighton

9 Test Hole Number: P-2 Project Perris Ellis Commons Date Excavated: 4/6/2017 Project Number Tested by: BSS Date Tested 4/7/2017 Soil Unit: Qal Depth of Test Hole (in.) USCS Soil Type: SM Diameter (in.) 8 Effective Radius (in) 3.5 t Total Initial Water Depth Final Water Depth Change In Water Level Infiltration Rate* (inches/hour) Peroclation Rate (minute/inch) 10:32:00 10:42:00 10:43:00 10:53:00 10:54:00 11:24:00 11:26:00 11:56:00 11:57:00 12:27:00 12:29:00 12:59:00 13:01:00 13:31:00 13:33:00 14:03: Infiltration Rate (in./hr) * Based on Porchet Method Percolation Project Number: Test Data Project Name: Perris Ellis Commons P-2 Date: Apr-17 Leighton

10 Test Hole Number: Date Excavated: Tested by: Soil Unit: USCS Soil Type: P-3 Project Perris Ellis Commons 4/6/2017 Project Number BSS Date Tested 4/7/2017 Qal Depth of Test Hole (in.) SM Diameter (in.) 8 Effective Radius (in) 3.5 t Total Initial Water Depth Final Water Depth Change In Water Level Infiltration Rate* (inches/hour) Peroclation Rate (minute/inch) 11:45:00 11:55:00 11:55:00 12:05:00 12:05:00 12:35:00 12:35:00 13:05:00 13:05:00 13:35:00 13:35:00 14:05:00 14:05:00 14:35:00 14:35:00 15:05: Infiltration Rate (in./hr) * Based on Porchet Method Percolation Project Number: Test Data Project Name: Perris Ellis Commons P-3 Date: Apr-17 Leighton

11 Test Hole Number: P-4 Project Perris Ellis Commons Date Excavated: 4/6/2017 Project Number Tested by: BSS Date Tested 4/7/2017 Soil Unit: Qal/Kgr Depth of Test Hole (in.) USCS Soil Type: SM Diameter (in.) 8 Effective Radius (in) 3.5 t Total Initial Water Depth Final Water Depth Change In Water Level Infiltration Rate* (inches/hour) Peroclation Rate (minute/inch) 11:46:00 11:56:00 11:56:00 12:06:00 12:06:00 12:36: N/A N/A N/A Infiltration Rate (in./hr) * Based on Porchet Method Percolation Project Number: Test Data Project Name: Perris Ellis Commons P-4 Date: Apr-17 Leighton

12 Project No. Project Drilling Co. Drilling Method Location Elevation Feet 1460 Depth Feet 0 N Graphic Log S Perris Ellis Commons 2R Drilling Hollow Stem Auger - 140lb - Autohammer - 30" Drop See Field Exploration Plan Attitudes Sample No. B-1 GEOTECHNICAL BORING LOG LB-3 Blows Per 6 Inches Dry Density pcf Moisture Content, % Soil Class. (U.S.C.S.) SM Date Drilled Logged By Hole Diameter Ground Elevation Sampled By SOIL DESCRIPTION Quaternary Alluvium (Qal): SILTY SAND, medium dense, brown, dry to moist, fine sand BSS 8" 1461' BSS This Soil Description applies only to a location of the exploration at the time of sampling. Subsurface conditions may differ at other locations and may change with time. The description is a simplification of the actual conditions encountered. Transitions between soil types may be gradual. Type of Tests R '' SP Granitic Bedrock (Kgr): Poorly graded SAND, very dense, brown, dry to moist, fine to medium sand R '' very dense, light yellowish brown, dry to moist, fine to coarse sand, micaceous R '' very dense, grayish brown, moist, fine to coarse sand, micaceous, some silt R '' very dense, grayish brown, moist, fine to coarse sand, (sample disturbed) Drilled to 20' Sampled to 20.2' Groundwater not encountered Backfilled with soil cuttings (4/6/17) SAMPLE TYPES: B BULK SAMPLE C CORE SAMPLE G GRAB SAMPLE R RING SAMPLE S SPLIT SPOON SAMPLE T TUBE SAMPLE TYPE OF TESTS: -200 % FINES PASSING AL ATTERBERG LIMITS CN CONSOLIDATION CO COLLAPSE CR CORROSION CU UNDRAINED TRIAXIAL DS EI H MD PP RV DIRECT SHEAR EXPANSION INDEX HYDROMETER MAXIMUM DENSITY POCKET PENETROMETER R VALUE * * * This log is a part of a report by Leighton and should not be used as a stand-alone document. * * * SA SE SG UC SIEVE ANALYSIS SAND EQUIVALENT SPECIFIC GRAVITY UNCONFINED COMPRESSIVE STRENGTH Page 1 of 1

13 Project No. Project Drilling Co. Drilling Method Location Elevation Feet 1465 Depth Feet 0 N Graphic Log S Perris Ellis Commons 2R Drilling Hollow Stem Auger - 140lb - Autohammer - 30" Drop See Field Exploration Plan Attitudes Sample No. B-1 GEOTECHNICAL BORING LOG LB-4 Blows Per 6 Inches Dry Density pcf Moisture Content, % Soil Class. (U.S.C.S.) SM Date Drilled Logged By Hole Diameter Ground Elevation Sampled By SOIL DESCRIPTION Quaternary Alluvium (Qal): SILTY SAND, medium dense, light brown, dry, fine sand BSS 8" 1465' BSS This Soil Description applies only to a location of the exploration at the time of sampling. Subsurface conditions may differ at other locations and may change with time. The description is a simplification of the actual conditions encountered. Transitions between soil types may be gradual. Type of Tests R dense, light brown, dry, fine sand, to Sandy SILT Granitic Bedrock (Kgr): R '' SP Poorly graded SAND, very dense, light brownish gray, dry to moist, fine to coarse sand, micaceous R-3 B '' very dense, light gray, dry to moist, fine to coarse sand with fine gravel, micaceous R '' very dense, light gray, dry to moist, fine to coarse sand, (bad recovery) Drilled to 20' Sampled to 20.5' Groundwater not encountered Backfilled with soil cuttings (4/6/17) SAMPLE TYPES: B BULK SAMPLE C CORE SAMPLE G GRAB SAMPLE R RING SAMPLE S SPLIT SPOON SAMPLE T TUBE SAMPLE TYPE OF TESTS: -200 % FINES PASSING AL ATTERBERG LIMITS CN CONSOLIDATION CO COLLAPSE CR CORROSION CU UNDRAINED TRIAXIAL DS EI H MD PP RV DIRECT SHEAR EXPANSION INDEX HYDROMETER MAXIMUM DENSITY POCKET PENETROMETER R VALUE * * * This log is a part of a report by Leighton and should not be used as a stand-alone document. * * * SA SE SG UC SIEVE ANALYSIS SAND EQUIVALENT SPECIFIC GRAVITY UNCONFINED COMPRESSIVE STRENGTH Page 1 of 1