20201654 Ver 2_Mulberry_Bio-retention Pond_SHWT_07-12-22_20220714

__________________________________________________________________________________
PO BOX 2155 ASHEVILLE, NORTH CAROLINA 28802
Phone: [phone] Fax: [phone] Email: [e-mail]

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aLPHA
Alpha Environmental
Alpha Engineering Services, P.A.

July 12, 2022

Mr. Marvin Mercer, Principle
MDG ENGINEERING
P.O. BOX 1516
WEAVERVILLE, NC 28787

Re: Seasonal High Water Table Report
Mulberry Farms
Marshall, NC 28753

Dear Mr. Mercer:

Alpha has predicted the seasonal high-water table (SHWT) for the above site to be 3.1’ feet below the current undisturbed
surface grade at the proposed bio-retention pond location. Based on the sample from the boring at the approximate center of
the proposed pond, the infiltration rate for the soils is estimated to be less-than 0.2 in/hr.

Discussion: A seasonal high-water table (SHWT) is the shallowest depth to free water that stands in an unlined borehole or
where the soil moisture tension is zero for a significant period (more than a few weeks) (Watts and Hurt, 1991). Although the
published sources of information such as the Soil Conservation Service generally provide reliable preliminary guidance on the
depth to the water table, Alpha conducted a site-specific investigation for comparison to the published data. This consisted of
measuring the stabilized groundwater level in a newly opened borehole, or piezometer at a selected location and time;
evaluating the soil profile in the test hole (i.e., sand, silty sand, clayey sand, etc.), including its redoximorphic features; and by
performing testing of soil samples from the Site.

Conclusion: Alpha’s prediction correlates to The Soil Conservation Service (SCS) of the United State s Department of
Agriculture mapping for the general area as having moderate depth soil and groundwater table conditions of more than 24
inches.

Alpha Environmental greatly appreciates the opportunity to conduct this investigation and provide this study an d looks
forward to working with you on the site development for the project. Please contact us for any additional questions regarding
this report.

Sincerely,
Alpha Environmental

Mark Von Dollen, PE
Engineer
Attachments: Soil Laboratory Results
Piezometer readings
ALPHA Soils and Materials Laboratory
Soil Grainsize Distribution
ASTM D6913 / D422-63
MV Testing Date:7/13/2022 ML
4 0.00 0.00 0.0 100.0
20 8.80 8.80 6.6 93.4
40 17.34 26.14 19.7 80.3
80 23.51 49.65 37.3 62.7
100 3.32 52.97 39.8 60.2
200 0.91 53.88 40.5 59.5
Passing 200 0.00 132.99 100.0 0.0
0.010.00039
United Soil Classification System
4.76
0.84
0.42
0.21
0.149
0.0740.0029
Weight
Retained (g)
Cumulative
Weight
Retained (g)
Amount Washed Through #200 (g)
Very Fine Sand
Fines (Silts/Clays)
Sieve Size
Number
0.187
0.33
0.0165
0.0083
0.0059
Gravel
Grain Size Description
Coarse Sand
Medium Sand
Medium Fine Sand
Fine Sand
Cumulative
% Retained
Cumulative
% Finer
Reported By:
Sieve Opening Size
(inches)
Sieve Opening Size
(millimeters)
132.99
53.88
79.11
Percent passing 200 59.49
Sample Amount Post Wash Dry + Pan (g)
Weigh of Pan Empty/Clean (g)
188.50
134.62
Sample Amount Pre Wash Dry (g)
Sample Amount Post Wash Dry (g)
Sample Field Description (From Bore Logs): Grey sandy silt (ML)
Sample Amount Pre Wash Wet + Pan (g)
Sample Amount Pre Wash Dry + Pan (g)
228.22
267.61
S1
Bio-Retention Pond
5' t 10'
7/1/2022
Client :
Contact:
Mercer Design Group
Marvin Mercer
Sample ID:
Sampled From:
Sample Depth
Sample Date:
Project :
Project Number:
Mulberry Farms
20263.5
0
10
20
30
40
50
60
70
80
90
100
0.010.1110Percent Finer By WeightGrain Size in Millimeters
Grain Size Distribution
ALPHA
Proctor Test
ASTM D698
Project _______Mulberry Farms_______
Project Number:__20263.50___________
Comments:
Method:
5.5 4
ft³
3
Tin ID #
24
1 2 3 4 5 6
6124.9 6231.7 6318.4 6280.1 6235.7
4325.1 4325.1 4325.1 4325.1 4325.1
1799.8 1906.6 1993.3 1955 1910.6
118.9295 125.9868 131.7159 129.185 126.2511
16 18 20 22 24
102.5254 106.7685 109.7632 105.8894 101.8154
Q7 7 3 6 P22
30 30.32 30.07 30.87 30.4
61.22 84.51 64.77 109.57 75.54
58.4 78.81 60.57 98.58 68.6
9.929577 11.755 13.77049 16.23099 18.16754
108.187 112.7348 115.7733 111.1451 106.8408
Field Data
Maximum Dry Density:115.8pcf Optimum Moisture :__13.8%
Tested By: MV Date: 07-13-22
Weight of Hammer:
A
25
Initial Moisture Content (%) Calculation
inchespoundsMold Diameter
Mold Volume: [A] Mold Volume Factor:
101.07 313.7 346.6 15.5
Sample Number: S-1 Proctor Number: Pond -1 Sampled By: ASD Date: 07-01-22
Tin Weight (g.) Tin+Dry Soil (g.) Tin+Wet Soil (g.) Initial Moisture Content (%)
Number of Layers (Lifts): Number of Blows Per Lift:
301/30
Sample Location
Bio-Rentention Pond
Actual Dry Density
Test Number:
[B] Soil + Mold Weight (g)
[C] Mold Weight (g)
[B-C=D] Net Soil Weight (g)
[(D/454)/A]=E Wet Density
[F] Assumed Water Content (%)
Proctor Test Laboratory Worksheet
Actual Moisture Content (%)
Moisture Tin ID
[(E/(1+(F/100))] Assumed Dry Density
[G] Weight of Moisture Tin (g)
[H] Moisture Tin + Wet Soil (g)
[J] Moisture Tin + Dry Soil
Description Including Unified Soil Classification ID: Grey sandy silt
In-Situ Water Content ( % - Moisture ):15.50%
106
108
110
112
114
116
9.8 10.8 11.8 12.8 13.8 14.8 15.8 16.8 17.8
Proctor Test Results
Project No:20263.5
Project Name:
Project Location:
Tested By: MV Date Tested: 7/13/2022 Date Weighed: 7/13/2022
Sample ID. 1
Sample Date 7/1/2022
Sample Description (From Bore
Log)Grey sandy silt (ML)
Boring No. 1
Container No. (cup) 24
Mass of Cup + Wet Soil (A)346.6
Mass of Cup + Dry Soil (B)313.7
Mass of Cup (C)101.07
Mass of Dry Soil (B-C)212.63
Mass of Water (A-B)32.9
Water Content% (A-B/D) x 100 15.5
ALPHA Materials Engineering Division
Water Content Laboratory Analysis
Mulberry Farms
Marshall
SHWT Water Content
Well ID Date Installed
(m/dd/yy)
Date Water
Level
Measured
(m/dd/yy)
Well Casing
Depth
(ft. BGS)
Screened
Interval (x to y
ft. BGS)
Bottom
of Well
(ft. BGS)
Top of
Casing
Elevation
(ft.)
Depth to Water
from ground
surface (ft.)
Free Product
Thickness (ft.)
Groundwater
Elevation (ft.)Comments
MW-1 7/1/2022 7/1/2022 6.80
MW-1 7/1/2022 7/7/2022 5.10
GROUNDWATER MONITORING REPORT
Project No.:
Mulberry Farms
Marshall, NC
20363.5
Site Name:
City/Sate:
aLPHA
Alpha Environmental
Alpha Engineering Services, P.A.