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.
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