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Lavender Place Sub-Geotech Report V1Consultinq, Soil Evaluations & Data Collection January 11, 2022 Ben Thomas, PE Civil Innovations, PLLC 1043 E. Park Blvd. Ste. 101 Boise, ID 83712 RE: Soil conditions on proposed Lavender Heights Subdivision site HARLEYR. NOE Phone: 208.850.4926 harley.noe@outlook.com Yesterday you contacted me requesting my opinion on soil conditions on the 55-acre Lavender Heights project located north of Lake Hazel Road and east of Locust Grove Road. You provided me with historical data which I collected from this parcel in 2006. That work was part of the larger 1000-acre area then known as the Provence/Springhill subdivision and is attached to this document. Six of the 2006 excavations are included in or adjacent to your Lavender Heights site (map attached for reference). The soil profile descriptions show a 10 to 12 inch thick surface layer of silt loam or silty clay loam overlying weak to strongly cemented hardpan. These pans are quite thick ranging from 12 to 68 inches thick. They dug with slight to moderate difficulty with a wheel rubber tire backhoe. Sands containing 35 to 65 percent gravel & cobbles are present beneath the hardpan. Those pit run materials extend to more than 12 feet below ground level. There are no limitations for these soils for the intended use. Larger excavators will have little difficulty digging in these materials. No bedrock was encountered in the test pits and no free water or evidence of wetness was observed in any of the excavations. I have biweekly groundwater monitoring from the Provence site collected from May 6th through October 1 Oth in 2006. All piezometers remained dry for the 11 readings during the summer season. In 2018 through 2021 we conducted monthly groundwater monitoring from March to October on some 17 locations on properties south and west of this Lavender property. All pipes remained dry to the installed depth of 12 to 17 feet below ground level. The recent data is just additional support for that large field of monitoring. These soils developed over a million years consisting mostly of Pleistocene outwash from glaciers. The data collected in 2006 is still a sound representation of the current soil conditions and is the best available information for your project. Groundwater is not present to more than 14 feet and will remain as indicated in the monitor data. transmitted via e-mail HARLEY R. NOE Professional Soil Scientist 5740 N. APPLEBROOK WAY BOISE, IDAHO 83713 ASSOCIATED EARTH ,SCIENCES, Inc. SEPTIC SOILS EVALUATIONS - STORM DRAIN SOILS DATA - SOIL SURVEYS - SOIL WETLAND INVESTIGATIONS R-VALUE SAMPLING — GEOLOGY INVESTIGATIONS - SITE INVESTIGATION Glen H. Logan 6238 Edgewater Drive Boise, Idaho 83709 Phone: (208) 672-9213 FAX: (208) 672-9214 Cell: (208) 941-7284 Harley R. Noe 5740 N. Applebrook Way Boise, Idaho, 83713 Phone & FAX: (208) 939-8602 Cell: (208) 850-4926 Mark E. Johnson 1886 N. Greenfield Avenue Meridian, Idaho, 83642 Phone & FAX: (208) 898-9541 Cell: (208) 869-9099 May 19, 2006 Kent Brown Bailey Engineering, Inc. 1500 E. Iron Eagle Drive Eagle, ID 83616 RE: Soils evaluation on Provence Subdivision parcels As requested I have conducted a soils evaluation on approximately 960 acres east of Meridian Road, north of Columbia Road and south of Amity Road. The parcels are in Sections 5 and 6 of Township 2 North, Range 1 East and Sections 31 and 32 of Township 3 North, Range 1 East. A large scale map is attached showing approximate boundaries of all four parcels. Also attached is a detailed map of each site showing test hole locations. Soil conditions on the site that were evaluated include: soil textures, depth to and strength of hardpans, depth to underlying sand and gravel or bedrock, slopes, permeability and soil groundwater levels. My approach to this project was to place test holes so that maximum benefit could be accomplished for the entire project area with a minimum number of excavations. By using this approach, soil information from one parcel could be utilized to predict conditions over the entire project area. I utilized an overlay of the Ada County Soil Survey to indicate areas needing investigation and selected potential dig locations. I then visited the sites and adjusted locations based on landscape features and field boundaries. Some of the preliminary dig locations were eliminated once field conditions were considered. A total of 43 test holes were examined and described. Copies of the detailed descriptions are attached. Data from an additional 12 test holes from 2003 was also utilized in the evaluation. Those descriptions were provided to you at an earlier date. No free water or evidence of wetness was observed in any of the test holes. Monitor pipes were placed in 10 excavations, located in low landscape positions, to allow for monitoring to verify presence or absence of groundwater. We will measure and record that information on a biweekly basis and provide you with a report on the results. The field descriptions indicate that there are three different soil groups present on the site. The three areas have been delineated on the attached interpretive map and are as follows: SOIL ZONE A — This group of soils has loam, silt loam, silty clay loam and silty clay textures in the upper horizons. A moderately to strongly cemented hardpan (or series of hardpans) is present at 20 to 40 inches below ground level. Beneath the hardpan are loam or sandy loam soils that are underlain by sand and gravel at depths of from 45 to 150 inches. No bedrock was observed in any profiles in this delineation. This delineation is 67% of the project area. Provence soils —page 2 SOIL ZONE B — These soils have silt loam and silty clay loam surface textures with clay contents of 20 to 35 percent. Hardpans are present below 20 inches and are underlain by basalt bedrock at depths ranging from 94 to 166 inches. This delineation makes up 16% of the project area. SOIL ZONE C — This area has silt loam and silty clay loam upper horizons containing 15 to 40 percent clay. Hardpans are present below a depth of 20 inches with bedrock directly underlying the hardpans at depths of 27 to 70 inches. Some areas have about 10% surface rock fragments. This area comprises 17% of the project area. The majority of this property has no significant soil conditions that would cause problems in development. Slopes are generally 1 to 3 percent with some sideslopes having slopes up to 10 percent. The relatively shallow bedrock present in the south part of Section 6 is the only area with depth limitations due to bedrock and should be an area of concern. The hardpans present over the entire property should dig with limited difficulty with larger excavators. These hardpans have very slow permeability and should be breached removed where storm drain facilities are installed to allow for free drainage. There should be no limitations for standard footings for dwellings. Building lots should be evaluated individually if basements are being considered. It should be noted that in delineations A & B in Section 6 there may be small areas where bedrock is shallower than 20 inches. Inclusions of small areas shallower than 20 inches to hardpan may also be present in the remainder of the project area. If you have questions or need anything additional, please call me at 850-4926. HARLEY R. NOE Professional Soil Scientist cc w/ attachments: Greg Johnson, Springhill, LLC, Meridian, ID Associated Earth Sciences, Inc. Storm Drain Test Hole Description & Evaluation Date Of Evaluation: 5/9/2006 Evaluated by: Harley Noe, Professional soil Scientist Requested By: Springhill, LLC (Westpark Company) Address: P. O. Box 344 Phone: 888-9946 City: Meridian State: ID Zip: 83680 Legal Desc: Part of the Southwest 1/4 of Section 32, Township 3 North, Range 1 East, Boise Meridian, Ada County General Desc: Provence Subdivision site - Section 32 portion, at the NE corner of Lake Hazel and Locust Grove Depth Color Texture Clay % Roots Mottles Est. Permeability Comments (inches) (in/hr) Hole Number & Location: 7-06 6324 0 to 10 10YR 3/3 silt loam 18 to 20 many very fine & fine; few medium none 1 to 2 very friable moist 10 to 21 10YR 7/3 moderately cemented hardpan few very fine & fine in fractures none 0.5 to 1 moderately fractured; digs with little difficulty 21 to 47 Ivariegated weakly cemented very gravelly sand <3 none none 12 to 15 moderately dense in place; 15% cobble 47 to 120+ variegated extremely gravelly sand <3 none none 15 to 20+ loose; 20% cobbles General Notes: Slope 2 to 4 percent. At lower end of pasture. Hole Number & Location: 8-06 6325 0 to 12 10YR 3/3 silt loam 22 to 26 common very fine & fine; few medium none 0.5 to 1 very friable moist 12 to 37 10YR 7/4 strongly cemented hardpan few very fine & fine in upper 10" none <0.5 moderately fractured; roots in fractures only; digs w/ great difficulty 37 to 64 10YR 7/3 weakly cemented sandy loam 10 to 12 none none 0.5 to 1 brittle moist chunks; difficult to texture; dense in place 64 to 144+ variegated extremely gravelly sand <3 none none 15 to 20+ loose; 20% cobbles General Notes: Slope 0 to 2 percent. On ridge position in pasture. Hardpan digs with difficulty. Associated Earth Storm Drain Test Hole Description &Evaluation Sciences, Inc. Continuation Sheet Date Of Evaluation: 5/9/2006 Project: Provence Subdivision site -- Section 32 portion Depth Color Texture Clay % Roots Mottles Est. Perm. Comments (inches) (in/hr) Hole Number & Location: 9-06 6326 0 to 10 10YR 3/3 silty clay loam 28 to 30 many very fine & fine; common medium none 0.2 to 0.6 friable moist 10 to 16 10YR 5/4 silt loam 24 to 26 common very fine, fin & medium none 0.5 to 1 very friable moist 16 to 37 10YR 7/3 moderately to strongly cementec hardpan few very fine & fine in fractures none 1 to 2 moderately to highly fractured; digs without difficulty 37 to 63 10YR 7/3 to variegated weakly cemented very gravelly loamy coarse sand 3 to 5 none none 10 to 12 10% cobbles 63 to 144+ variegated very gravelly sand <3 none none + 15 to 20% cobbles General Notes: Slope 1 to 3 percent. Along canal on upland. No free water or evidence of wetness. Hole Number & Location: 1 0-06 6327 0 to 9 10YR 3/2 silty clay loam 35 to 40 common very fine, fin I&medium none 0.06 to 0.2 firm moist 9 to 25 10YR 3/4 silty clay 40 to 45 few very fine & fine none <0.02 firm moist 25 to 42 10YR 6/3 1& 3/3 silt loam 20 to 22 few very fine & fine none 0.5 to 1 friable moist; 20% fine brittle moist fragments 42 to 50+ 10YR 3/4 & 6/6 strongly cemented hardpan none none 0.2 to 0.6 few fractures; digs w/ great difficulty General Notes: Slope 0 to 2 percent. Fall grain. Pan very hard to dig. Excavation discontinued at 50 ". Associated Earth Storm Drain Test Hole Description &Evaluation Sciences, Inc. Continuation Sheet Date Of Evaluation: 5/9/2006 Project: Provence Subdivision site -- Section 32 portion Depth Color Texture Clay % Roots Mottles Est. Perm. Comments (inches) (in/hr) Hole Number & Location: 1 1 -06 6328 0 to 12 10YR 3/3 silty clay loam 28 to 30 many very fine & fine; common medium & coarse none 0.2 to 0.6 very friable moist 12 to 22 10YR 5/4 silt loam 22 to 24 common very fine & fine; few medium none 0.5 to 1 friable moist 22 to 67 10YR 5/3 silt loam 10 to 12 few very fine, fine & medium none 1 to 2 very friable moist; approaches very fine sandy loam 67 to 144+ grayish variegated very gravelly sand <2 1none none 15 to 20+ loose; 15% cobbles General Notes: Slope 1 to 2 percent. Along canal. No evidence of wetness. Hole Number & Location: 1 2-06 6329 0 to 12 10YR 3/3 silty clay loam 30 to 32 many very fine & fine; common medium; few coarse none 0.2 to 0.6 friable moist 12 to 39 10YR 6/4 strongly cemented hardpan few very fine & fine in upper 12" none <0.5 moderately fractured; roots in fractures; digs w/ difficulty 39 to 80 10YR 4/6 1& 7/4 weakly cemented hardpan none none 1 to 2 highly fractured; brittle moist plates; digs w/ little difficulty 80 to 144+ grayish variegated extremely gravelly sand <3 none none 15 to 20+ loose; 15 to 20% General Notes: Slope 0 to 2 percent. Along canal. Water in canal is above surrounding ground level. No wetness or free water. � '� • pia' �' �.+� CL m t C q . _ �I 4-- 0 O O 0 •• s • Locust Grove Road w N _-- �• i chi r C O - 0 Z � V M Q(n()H 140