HomeMy WebLinkAboutSDP 16-07; OLIVENHAIN MUNICIPAL WATER DIST; SUPPLEMENTAL INFILTRATION ASSESSMENT; 2018-05-01SCSI, Inc.
Corporate Headquarters
6280 Piverdale Street
San Diego, CA 92120
T 877.215.4321
P 619.280.4321
619.260.4717
W www.scst.com
SDVOSB . DVBE
May 1, 2018 SCST No. 180197124
Report No. I
David Padilla, P.E.
Project Manager
Infrastructure Engineering Corporation
14271 Danielson Street
Poway, California 92064
Subject: GLJ?PLEMENTAL INFILTRATION ASSESSMENT
OLIVENHAiiMUNICIPAL WATER DISTRICT BUILDING D
1966 OLIVENHAIN ROAD
CARLSBAD, CALIFORNIA
Reference: SCSI, Inc. (2016), Geotechnical Invegtion, Olivenhain Municipal Water District
Building D, 1966 Oliëhhain Road, Encinitas, California, SCST No. 160105P3-1,
March 3.
Dear Dave:
This report presents the results of the supplemental infiltration assessment SCSI, Inc. (SCSI)
performed for the subject project. We understand the project will consist of the design and
construction of a one-story building, pavements, and stormwater BMPs. We previously performed
the referenced geotechnical investigation that included an infiltration assessment for the BMPs
proposed at that time. However, after performing our investigation, a new BMP (Basin 6) was
added in an area we didn't investigate. Our scope of work for this infiltration assessment
consisted of performing supplemental subsurface exploration and percolation testing in the area
of proposed Basin 6. Figure 1 presents a site vicinity map.
SUPPLEMENTAL SUBSURFACE EXPLORATION
Our supplemental subsurface exploration consisted of drilling one boring to estimate the
groundwater depth and two percolation test' borings to assess the infiltration rate. The
groundwater boring was drilled to a depth of about 15 feet below the existing ground surface
using a truck-mounted drill rig equipped with a hollow stem auger. The percolation test borings
were drilled to a depth of about 2 feet below the existing ground surface using a hand auger.
Figure 2 shows the approximate locations of our current borings as well as our previous borings.
An SCSI geologist logged the borings and collected soil samples for laboratory testing. Logs of
the current borings are presented in Appendix I. Soils are classified according to the Unified Soil
Classification System illustrated on Figure I-I. Young alluvial floodplain deposits consisting of
loose to medium dense silty sand with varying amounts of gravel were encountered in the current
borings. Groundwater was encountered at a depth of 11 feet below the existing ground surface.
Infrastructure Engineering Corporation May 1, 2018
Olivenhain Municipal Water District Building D SCST No. 180197P4-1
Carlsbad, California Page 2
LABORATORY TESTING
Selected soil samples obtained from the borings were tested to determine soil classification and
develop geotechnical conclusions. The laboratory testing consisted of particle-size distribution
and Atterberg limits. The results of the laboratory testing and brief explanations of the test
procedures are presented in Appendix II.
PERCOLATION TESTING
We performed two borehole percolation tests at the approximate locations shown on Figure 2 to
assess stormwater infiltration feasibility. Appendix III presents the field data and test results. The
table below presents the tested infiltration rates.
Infiltration Rate Test Results
Test
Location
Test Depth
(feet) Material Type at Test Depth Infiltration Rate
(inch/hour)
P-5 2 Young alluvial flood-plain deposits: Silty Sand 1.2
P-6 2 Young alluvial flood-plain deposits: Silty Sand 0.6
Based on our test results, the feasibility screening category is Full Infiltration.
If you have any questions, please call us at (619) 280-4321.
Respectfully
SCST, INC.
omas B. Canady,
Principal Engineer
TBC:DAS:djm:hu
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(1) Addressee via e-mail: dpadilla@iecorporation.com
Attachments:
Figures
Figure 1 - Site Vicinity Map
Figure 2- Subsurface Exploration Map
Appendices
Appendix I - Subsurface Exploration
Appendix II - Laboratory Testing
Appendix III - Infiltration Rate Test Results
(1) Addressee via email atdpadilla@iecorporation.com
S I
T
0 60 120
-:
OLIVENHAIN ROAD
SCALE - NL
-- ------ \ F
\
'(39/ 00 1
/
SCST LEGEND: P-5
(2)L
B-5 4 Current Boring
(15) (Depth in Feet) 1 (5)-"
Current Percolation / P-6•/
P-6 • Test Boring (2 < 41Mm /
(Depth in Feet)
_Previous Boring
(Depth in Feet)
Previous Percolation
Test Boring - -
(5) (Depth in Feet) N
Proposed Basin 6
14
C SUBSURFACE EXPLORATION MAP Date: May, 2018 Figure:
SCST, Inc. Olivenhain Municipal Water District Building D By: PFL
S H San Diego, California Job No.: 180197P4-1 2
APPENDIX I
APPENDIX I
SUBSURFACE EXPLORATION
Standard Penetration Tests (SPT) were performed using a 2-inch outer diameter and 1%-inch
inner diameter split tube sampler. The SPT samplers were driven by a 140-pound weight
dropping 30 inches. The number of blows needed to drive the samplers the final 12 inches of an
18-inch drive is noted on the boring logs as "Driving Resistance (blows/ft. of drive)." The SPT
penetration resistance was normalized to a safety hammer (cathead and rope) with a 60%
energy transfer ratio in accordance with ASTM 06066. The normalized SPT penetration
resistance is noted on the boring logs as "N60." Disturbed bulk samples were obtained from the
SPT sampler and the drill cuttings.
The soils are classified in accordance with the Unified Soil Classification System as illustrated
on Figure I-I. Logs of the borings are presented on Figures 1-2 through 1-4.
SUBSURFACE EXPLORATION LEGEND
UNIFIED SOIL CLASSIFICATION CHART
SOIL DESCRIPTION GROUP TYPICAL NAMES SYMBOL
COARSE GRAINED, more than 50% of material is larger than No. 200 sieve size.
GRAVELS CLEAN GRAVELS GW More than half of Well graded gravels, gravel-sand mixtures, little or no fines
coarse fraction is GP larger than No. 4 Poorly graded gravels, gravel sand mixtures, little or no fines.
sieve size but GRAVELS WITH FINES GM smaller than 3".
Silty gravels, poorly graded gravel-sand-silt mixtures.
(Appreciable amount of
fines) GC Clayey gravels, poorly graded gravel-sand, clay mixtures.
SANDS CLEAN SANDS SW More than half of Well graded sand, gravelly sands, little or no fines.
coarse fraction IS SP smaller than No. Poorly graded sands, gravelly sands, little or no fines.
4 sieve size. SM Silty sands, poorly graded sand and silty mixtures.
SC Clayey sands, poorly graded sand and day mixtures.
FINE GRAINED, more than 50% of material is smaller than No. 200 sieve size.
SILTS AND CLAYS ML Inorganic silts and very fine sands, rock flour, sandy silt or clayey-silt-
(Liquid Limit less sand mixtures with slight plasticity.
than 50) CL Inorganic clays of low to medium plasticity, gravelly clays, sandy clays,
silty clays, lean days.
OL Organic silts and organic silty clays or low plasticity.
SILTS AND CLAYS MH Inorganic silts, micaceous or diatomaceous fine sandy or silty soils,
(Liquid Limit elastic silts.
greater than 50) CH Inorganic days of high plasticity, fat days.
OH Organic clays of medium to high plasticity.
HIGHLY ORGANIC SOILS PT Peat and other highly organic soils.
SAMPLE SYMBOLS LABORATORY TEST SYMBOLS
- Bulk Sample AL - Atterberg Limits
CAL - Modified California Sampler CON - Consolidation
CK - Undisturbed Chunk sample CDR - Corrosivity Tests
MS - Maximum Size of Particle (Resistivity, pH, Chloride, Sulfate)
ST - Shelby Tube DS - Direct Shear
SPT - Standard Penetration Test sampler El - Expansion Index
MAX - Maximum Density
GROUNDWATER SYMBOLS RV - R-Value
-Water level at time of excavation or as indicated i SA - Sieve Analysis
- Water seepage at time of excavation or as indicated
Olivenhain Municipal Water District Building D
SCSI Inc.arlsbad, California
By: DJM I Date: May, 2018
I II
flC•
Job Number: 180197134-1 Figure: I-I
LOG OF BORING B-5
Date Drilled: 4/19/2018 Logged by: DJM
Equipment: CME 45 with 8-inch diameter Hollow Stem Auger Reviewed by: TBC
Elevation: 114% Feet MSL Depth to Groundwater (ft): 11
-
co SUMMARY OF SUBSURFACE CONDITIONS
SAMPLES u
Z I— Z W
16 0.
I— I
!
I—Cl)
W
-
!
-
- 2
-3
-4
-5
-6
-7
- 8
-9
-10
- 11
- 12
- 13
- 14
- 15
- 4 inches of asphalt concrete over 6 inches of aggregate base. - - -
7
15
-
9
20
- - -
SM YOUNG ALLUVIAL FLOOD PLAIN DEPOSITS (Qva): SILTY SAND,
loose, light brown, moist, fine to medium grained.
Brown.
Medium Dense.
Groundwater at 11 feet.
-
-
-
SPT
-
SPT
- 16
- 17
- 18
- 19
- 20
— BORING TERMINATED AT 15 FEET — — — — — — —
Olivenhain Municipal Water District Building 0
SCST, Inc. Carlsbad, California
By: DJM Date: May, 2018
III Job Number: 180197P4-1 (Figure: 1-3
LOG OF BORING P-5
Date Drilled: 4/19/2018 Logged by: DJM
Equipment: 6-inch diameter Hand Auger Reviewed by: TBC
- Elevation: 1141/2 Feet MSL Depth to Groundwater (ft): Not Encountered
SAMPLES U)
I— z
.9;
I— I
I— CO) w
. S2 I—
>- z co 0 0 W
D SUMMARY OF SUBSURFACE CONDITIONS ' w
zo
I— 0 Cl)
0
- — 4 inches of asphalt concrete over 6 inches of aggregate base. — — — — - — —
- SA YOUNG ALLUVIAL FLOOD PLAIN DEPOSITS (Ova): SILTY SAND, loose,
- 2 — !iqht brown, moist, fine to medium grained. .& BORING TERMINATED AT 2 FEET
-3
-4
-5
-6
-7
-8
-9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
No
Olivenhain Municipal Water District Building D
Carlsbad, California SCST, Inc.
Ion
By: DJM 'Date: May, 2018
Job Number: 180197P4-1 1Figure: 1-4
LOG OF BORING P-6
Date Drilled: 4/19/2018 Logged by: DJM
Equipment: 6-inch diameter Hand Auger Reviewed by: TBC
Elevation: 1141/2 Feet MSL Depth to Groundwater (ft): Not Encountered
SAMPLES
o
I_?
-.
Z LU
s
I- I
I-
w
-
SUMMARY OF SUBSURFACE CONDITIONS Z
-1
4 inches of asphalt concrete over 12 inches of aggregate base.
SA
- 2
-
-4
-5
-6
-7
-8
-9
- 10
- 11
- 12
- 13
-14
- 15
- 16
- 17
- 18
- 19
- 20
SM
\
YOUNG ALLUVIAL FLOOD PLAIN DEPOSITS (Ova): SILTY
SAND, loose, light brown, moist, fine to medium grained.
AL
BORING TERMINATED AT 2 FEET
APPENDIX II
APPENDIX II
LABORATORY TESTING
Laboratory tests were performed to provide geotechnical parameters for engineering analyses.
The following tests were performed:
CLASSIFICATION: Field classifications were verified in the laboratory by visual
examination. The final soil classifications • are in accordance with the Unified Soil
Classification System.
PARTICLE-SIZE DISTRIBUTION: The particle-size distribution was determined on two
soil samples in accordance with ASTM D422. Figures lI-I and 11-2 present the test
results.
ATTERBERG LIMITS: The Atterberg limits were determined on two soil samples in
accordance with ASTM 04318. Figures Il-I and 11-2 present the test results.
Soil samples not tested are now stored in our laboratory for future reference and analysis, if
needed. Unless notified to the contrary, all samples will be disposed of 30 days from the date of
this report.
U.S. Standuid Sims Slzi.
6' 3" 1-W 3/4" 3/8' #4 #8 910 #16 #30 #40#50 #100 #200
100
90
80
E iz 50
2 040
30 N
Is
20
10
1000 100 10 1 0.1 0.01
Grain Size in Millimeters
Cobbles Gravel Sand I Silt or Clay
Coarse I Fine I Coarse I Medium I Fine
SAMPLE LOCATION
P-5 at 1Y2to2 Feet
SAMPLE NUMBER
28519
UNIFIED SOIL CLASSIFICATION: I SM
DESCRIPTION I SILTY SAND
ATERBERG LIMITS
LIQUID LIMIT NP
PLASTIC LIMIT NP
PLASTICITY INDEX NP
I Olivenhain Municipal Water District Building 0
Carlsbad, California I SCST, Inc. By: DJM Date May, 2018
I u lJob Number: 180197124-1 jFigure: li-I I
U.S. Stmidid Sieve Sizes
6' 30 1-W 3/4° 3/8' #4 #8#10 #16 #30 #40#50 0100 #200
100
90
80
.9' 70
if 50
e 40
CL
30
20
10
1000 100 10 1 0.1 0.01
Grain Size in Millimeters
Cobbles Gravel Sand Silt or Clay
Coarse I Fine Coarse r Medium I Fine
SAMPLE LOCATION
P-6at1%t02 Feet
SAMPLE NUMBER
28520
UNIFIED SOIL CLASSIFICATION: I SM
DESCRIPTION I SILTY SAND
ATTERBERG LIMITS
LIQUID LIMIT NP
PLASTIC LIMIT NP
PLASTICITY INDEX NP
I Olivenhain Municipal Water District Building D
SCST, Inc. Carlsbad, California I
I
I IBy: DJM 'Date: May, 2018 I
I u IJob Number: 180197P4-1 IFigure: 11-2 I
APPENDIX III
APPENDIX Ill
INFILTRATION RATE TEST RESULTS
We performed falling head borehole percolation testing at two locations (P-5 and P-6) in general
conformance with Appendix C of the Model BMP Design Manual for San Diego Region. The
percolation test holes were prepared for testing by placing about 6 inches of W gravel in the
bottom of the test hole and then installing a 4-inch diameter solid PVC pipe from the top of the
W gravel to about % to 1 foot above the ground surface. W gravel was placed in the annular
space between the PVC pipe and the percolation test hole sidewall between the depths of about
11/2 feet and 2 feet below the ground surface. Prior to starting the percolation testing, the test
holes were presoaked overnight (approximately 24 hours) by filling the holes with water. The
percolation testing was performed immediately after presoaking by filling the test holes with
clean potable water to approximately 6 inches above the bottom of the PVC pipe and measuring
the drop in the water level every 10 minutes until a constant rate was established. Figures Ill-I
and 111-2 present the results of the testing.
Report of Borehole Percolation Testing
Project Name:
Job Number:
Date Drilled:
Drilling Method:
Drilled Depth (feet):
Test Hole Diameter (inches):
Gravel Pack:
Pipe Diameter (inches):
Storm Water Infiltration
Olivenhain Municipal Water District Building D
180197P4-1
4/19/2018
6-inch diameter Hand Auger
2.0
6
V
4
Test Number: P-S
Tested By: DJM
Date Tested: 4/20/2018
Presoak Time: 24 hours
Trial No. Time
Time
Interval, AT
(mm)
Initial Water
Height, H.
(ft)
Final Water
Height, Hf
(ft)
Change in Water
Height, AH
(in)
Percolation
Rate
(mm/in)
1 8:41 0:10 0.82 0.72 8:51
1.20 8
2 8:52 0:10 0.82 0.72 9:02
1.20 8
3 9:03 0:10 0.82 0.71 9:13
1.25 8
4 9:14 0:10 0.83 0.73 9:24
1.19 8
5 9:25 0:10 0.87 0.75 9:35
1.39 7
6 9:36 0:10 0.75 0.64 9:46
1.36 7
Observed Percolation Rate: 7 mm/in 8.2 in/hr
Gravel Correction Factor: 1.50
Corrected Percolation Rate: 11 mm/in 5.4 in/hr
Tested Infiltatlon Rate, It: 1.2 in/hr
*Tested infiltration rate using the Porchet Method:
- AH(60r)
- AT(r + 2H)
AH = Change in water head height over the time interval [in] = 1.4
= Test hole radius [in] = 3
AT = Time interval [min] = 10
Han = Average water height over time interval = 12(H0 + Hf)/2 [in] = 8.3
I Olivenhain Municipal Water District Building D I
Carlsbad, California
I
SCST, Inc. By: DiM IDate: April, 2018
on
I
IJob No: 180197P4-1 iFigure: Ill-i
Report of Borehole Percolation Testing
Project Name:
Job Number:
Date Drilled:
Drilling Method:
Drilled Depth (feet):
Test Hole Diameter (inches):
Gravel Pack:
Pipe Diameter (inches):
Storm Water Infiltration
Olivenhain Municipal Water District Building D
180197P4-1
4/19/2018
6-inch diameter Hand Auger
2.0
Test Number: P-6
Tested By:DiM
Date Tested: 4/20/2018
Presoak Time:24hours
Trial No. Time
Time
Interval, AT
(mm)
Initial Water
Height, H.
(ft)
Final Water
Height, Hf
(ft)
Change in Water
Height, AH
(in)
Percolation
Rate
(mm/in)
1 9:55 0:10 0.79 0.72 10:05
0.90 11
2 10:06 0:10 0.72 0.66 10:16
0.72 14
3 10:17 0:10 0.82 0.73 10:27
1.08 9
4 10:28 0:10 0.86 0.80 10:38
0.72 14
5 10:39 0:10 0.81 0.74 10:49
0.78 13
6 10:50 0:10 0.87 0.81 11:00
0.72 14
Observed Percolation Rate: 14 mm/in 4.3 in/hr
Gravel Correction Factor: 1.50
Corrected Percolation Rate: 21 mm/in 2.9 in/hr
*Tested Infiltatlon Rate, It: 0.6 In/hr
= 0.7
=3
=10
= 10.0