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HomeMy WebLinkAboutPZ - Geotech Addendum November 8, 2021 Atlas No. B211602g Mr. Jackson Lane Lane Development LLC PO Box 608 Eagle, ID 83616 Subject: Addendum #1 — Infiltration Testing Linder & Ustick Mixed-Use 1515 West Ustick Road Meridian, ID Dear Mr. Lane: This addendum report presents infiltration testing results not requested at the time of the previously issued Atlas Geotechnical Engineering Report (B211602g). Descriptions of general site characteristics and the proposed project are available in the previous report. Unless otherwise noted in this addendum, all initial recommendations, limitations, and warranties expressed in the previous report must be adhered to. INFILTRATION TESTING Infiltration testing was conducted using an open test pit method. Test pit areas were selected by Hillcrest Construction and provided to Atlas via a site map. Test pit areas will need to be re- excavated and compacted prior to construction of structures that will be sensitive to settlement. Test locations were presoaked prior to testing. Pre-soaking increases soil moistures, which allows the tested soils to reach a saturated condition more readily during testing. Saturation of the tested soils is desirable in order to isolate the vertical component of infiltration by inhibiting horizontal seepage during testing. Testing was conducted on November 3, 2021. Details and results of testing are as follows: Table 1 — Infiltration Test Results Test Test Depth Stabilized Infiltration Design Infiltration Location (feet bgs) Soil Type Rate Rate (inches/hour) (inches per hour) TP-1 3.2 Poorly Graded Gravel 1.2 0.6 with Clay and Sand TP-2 3.1 Poorly Graded Gravel 1.8 0.9 with Clay and Sand TP-3 3.1 Poorly Graded Gravel 2.16 1.08 with Clay and Sand TP-4 3.3 Silty Clay with Sand 0.48 0.24 Atlas No. B211602g Page11 Copyright©2021 Atlas Technical Consultants rrN+O= 'T�� --1 Appropriate factors of safety have been applied to the stabilized infiltration rates achieved during testing to obtain the design infiltration rates listed above. The reason for the decreased infiltration rate is to account for long term saturation of the soils and the potential for less permeable soils to settle into the bottom of the infiltration facilities. Atlas recommends that all infiltration facilities be constructed in accordance with the local municipality requirements. If you have any questions, please call us at (208) 376-4748. Respectfully submitted, Clinton Wyllie, PG Monica Saculles, PE Staff Geologist Senior Geotechnical Engineer Attachments: Site Map Geotechnical Investigation Test Pit Logs Geotechnical General Notes Atlas No. B211602g Page12 Copyright©2021 Atlas Technical Consultants Site Map Figure 1 ® NOTES: SECTION CORNER �-_,•-��er—ram N�` •Not to Scale 3 112'BRASS CAP \ - _ •eP 1/4 CORNER CP&F No. 09109B99 _ BASIS OF BEARING - - - - - - — 3.25"BRASS CA PLS 35 T.4N_RAW.,B.M. V S 88'4X CP&F No. 5291 1 T.arv.,R-1V�,13,M, _ USTICK ROAD f 36 2017-120066 sal O _ _ O 7995-80' 1 PLS u 12087 rrr�� _ LEGEND CHISELED x 1 5�1_ - _ - MAG NAIL L5 A roximate Site ELEV.=2570.71' C Q 14 ELEV.=2571.52' 1118 pp + Q PL,$ - Boundary 52�1 i r f i ` Approximate Atlas Test 8 1 R y Pit Location lob � TP-2 3 q 104. TP 1 r � 8 L5 112°IRO I St ELEV.=2589.70��y �� 10 l © PLS Linder&Ustick Mixed-Use ti 1 1515 West Us tick Road Meridian,ID Modified by:CCW ' l r November 4,2021 } w \ � � } } Drawing:B211602g 112"IRON PIN TP O ELEV.=2569.36' N B PLS _ _ _ P�S� / y I 11118 - - = �f 91 18 J + /�T ■ -C pLS _ �_ _l�TL7T7� 11118 �Y - � + /4 CORNER 3 112" - 2791 S.Victory View Way Phone: (208)376-4748 BRASS CAP 2 1PL5 Boise,ID 83709 Fax: (208)322-6515 CP&F No. 0561 q Web: oneatlas.com �TrT-G7T�1 GEOTECHNICAL INVESTIGATION TF Test Pit Log #: TP-1 Latitude: 43.633216 Date Advanced: November 2, 2021 Longitude: -116.413126 Excavated by: Turn of the Century Homes Depth to Water Table: Not Encountered Logged by: Nabil Pasha, El Total Depth: 3.2 feet bgs V. Depth eld Description and USCS Soil and Sample Sample Depth ••s)it Sediment Classification • bgs) imm 0.0-2.6 Lean Clay(CL): Brown, slightly moist, medium 0.75-1.0 stiff, with fine to medium-grained sand. Poorly Graded Gravel with Clay and Sand 2.6-3.2 (GP-GC): Brown, slightly moist to moist, dense, with fine to coarse-grained sand, fine to coarse gravel, and 4-inch minus cobbles. Notes:See Site Map for test pit location. Infiltration testing conducted at a depth of 3.2 feet bgs. Atlas No. 13211602g Page14 Copyright©2021 Atlas Technical Consultants �TrT-G7T�1 GEOTECHNICAL INVESTIGATION TF Test Pit Log #: TP-2 Latitude: 43.633171 Date Advanced: November 2, 2021 Longitude: -116.411487 Excavated by: Turn of the Century Homes Depth to Water Table: Not Encountered Logged by: Nabil Pasha, El Total Depth: 3.1 feet bgs V. Depth eld Description and USCS Soil and Sample Sample Depth 11 � • ••s)I& Sediment Classification • •• 0.0-2.8 Lean Clay (CL): Brown, slightly moist, stiff to 2.0-2.5 very stiff, with fine-grained sand. Poorly Graded Gravel with Clay and Sand 2.8-3.1 (GP-GC): Brown, slightly moist to moist, dense, with fine to coarse-grained sand, fine to coarse gravel, and 4-inch minus cobbles. Notes:See Site Map for test pit location. Infiltration testing conducted at a depth of 3.1 feet bgs. Atlas No. 13211602g Page 15 Copyright©2021 Atlas Technical Consultants �TrT-G7T�1 GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log#: TP-3 Latitude: 43.633171 Date Advanced: November 2, 2021 Longitude: -116.411487 Excavated by: Turn of the Century Homes Depth to Water Table: Not Encountered Logged by: Nabil Pasha, El Total Depth: 3.1 feet bgs Depth ieldd Description and USCS Soil and Sample Sample Depth Qp Lab ••s) Sediment Classification • bgs) Test ID iw:i M I Silty Clay with Sand (CL-SM): Brown, moist, 0.0-2.7 medium stiff to stiff, with fine to medium- 1.0-1.5 grained sand. Poorly Graded Gravel with Clay and Sand 2.7-3.1 (GP-GC): Brown, moist, dense, with fine to coarse-grained sand, fine to coarse gravel, and 4-inch minus cobbles. Notes:See Site Map for test pit location. Infiltration testing conducted at a depth of 3.1 feet bgs. Atlas No. B211602g Page 16 Copyright©2021 Atlas Technical Consultants �TrT-G7T�1 GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log#: TP-4 Latitude: 43.632054 Date Advanced: November 2, 2021 Longitude: -116.412447 Excavated by: Turn of the Century Homes Depth to Water Table: Not Encountered Logged by: Nabil Pasha, El Total Depth: 3.2 feet bgs Depth ieldd Description and USCS Soil and Sample Sample Depth Qp Lab ••s) Sediment Classification • bgs) Test ID Silty Clay with Sand (CL-ML): Brown, slightly 0.0-3.3 moist, medium stiff to stiff, with fine-grained 1.0-1.5 sand. Notes:See Site Map for test pit location. Infiltration testing conducted at a depth of 3.3 feet bgs. Atlas No. B211602g Page 17 Copyright©2021 Atlas Technical Consultants �TrT-G7Tdr-W1 GEOTECHNICAL GENERAL NOTES Major Divisions Symbol Soil Descriptions Gravel & GW Well-graded ravels; ravel/sand mixtures with little or no fines Coarse- Gravelly Soils GP Poorly-graded ravels; ravel/sand mixtures with little or no fines Grained < 50% GM Silty gravels; poorly-graded ravel/sand/silt mixtures Soils < coarse GC Clayey gravels; poorly-graded gravel/sand/clay mixtures 50% Sand & Sandy SW Well-graded sands; gravelly sands with little or no fines passes Soils > 50% SP Poorl - raded sands; gravelly sands with little or no fines No.200 coarse SM Silty sands; poorly-graded sand/gravel/silt mixtures sieve fraction SC Clayey sands; poorly-graded sand/gravel/clay mixtures Fine- ML Inorganic silts; sandy, gravellyor clayey silts Grained Silts & Clays CL Lean clays; inorganic, gravelly, sandy, or silty, low to medium- Soils > LL < 50 plasticity clays 50% OL Organic, low-plasticity clays and silts passes Silts & Cl MH Inorganic, elastic silts; sand ravel) or clayey elastic silts ays No.200 CH Fat clays; high-plasticity, inorganic clays sieve LL > 50 OH Organic, medium to high-plasticity clays and silts Highly Organic Soils PT Peat, humus, h dric soils with high organic content ure Content and Cementation Classification Coarse-Grained Soils SPT Blow Counts N Description Field Test VeryLoose: <4 Dr Absence of moisture, dryto touch Loose: 4-10 Slightly Moist Damp, but no visible moisture Medium Dense: 10-30 Moist Visible moisture Dense: 30-50 Wet Visible free water Very Dense: > 50 Saturated Soil is usually below water table Fine-Grained Soils SPT Blow Counts (N) Description Field Test Very Soft: < 2 Weak Crumbles or breaks with handling or Soft: 2-4 slight finger pressure Medium Stiff: 4-8 Moderate Crumbles or breaks with Stiff: 8-15 considerable finger pressure Very Stiff: 15-30 Strong Will not crumble or break with finger Hard: > 30 pressure Boulders: > 12 in. GSI_ L�grab sample Cobbles: 12 to 3 in. LLi uid Limit Gravel: 3 in. to 5 mm Mmoisture content Coarse-Grained Sand: 5 to 0.6 mm NP non-plastic Medium-Grained Sand: 0.6 to 0.2 mm PI Plasticity Index Fine-Grained Sand: 0.2 to 0.075 mm Qp penetrometer value, unconfined compressive Silts: 0.075 to 0.005 mm strength, tsf Clays: < 0.005 mm V vane value, ultimate shearing strength, tsf Atlas No. B211602g Page 18 Copyright©2021 Atlas Technical Consultants