SW6091006_Soils Report_20090710

SOIL & SITE EVALUATION - STORMWATER BASINS
Indoor Firing Range
Proposed Site #2
Fort Bragg
Fayetteville, North Carolina
TCG Job # 7429
Prepared For:
Mr. Brian Dick, PH
Earth Tech I AECOM
701 Corporate Center Drive, Suite 475
Raleigh, NC 27607
Prepared By:
Co teno
Group,
The Catena Group, Inc.
410-B Millstone Drive
Hillsborough, NC 27278
Tel[phone] Fax[phone]
July 10, 2009
Michael Callahan

INTRODUCTION
Fort Bragg is planning the construction of an indoor firing range. As part of this expansion,
several stormwater infiltration basins are being considered to infiltrate runoff from adjacent
impervious surfaces. As part of the application process, a soils investigation detailing soil type,
infiltration rate, and depth to seasonal high water table is required. The Catena Group, Inc
(TCG) has been retained to perform the soil investigations. This report is a follow up to a
previously conducted evaluation on May 9, 2009, and.is being conducted d'ue to a proposed
change in location for the proposed stormwater structure.
INVESTIGATION METHODOLOGY
Prior to the field investigation, the Cumberland County Soil Survey was referenced to get an
overview of the possible soil series located in the study area. Around the site, there are three
mapped units (Table 1). Figure 1 presents the mapped soil series and figure 2 depicts the general
locations of the proposed infiltration basins where soil borings and infiltration tests were
performed.
Table I - Soil Series, Map Unit Symbol, and Taxonomic Class
Map Unit Symbol
Soil Series
Taxonomic Class
BaB
Blaney
thermic Arenic Ha ludult
BaD
Blaney
thermic Arenic Ha ludult
Tr
Johnston
thermic Cumulic Huma ue t
The field investigation for `Infiltration 3" was performed on July 7, 2009. Soil borings were
made with a hand -turned auger at the predetermined locations shown on Figure 2. Observations
of the landscape (slope, drainage patterns, past use, etc.) as well as soil properties (depth, texture,
structure, seasonal wetness, restrictive horizons, etc.) to a depth > 60 inches, when possible, were
recorded. Soil color was determined with a Munsell Soil Color Chart.
The rate of water entry into a soil is referred to as the infiltration rate. The infiltration rate into a
soil decreases with time mainly due to an increase in the soil water content and a decrease in the
hydraulic gradient. As infiltration continues, the rate of water entry into the soil reaches a
constant value (steady state condition), which is considered to be the same as the saturated
hydraulic conductivity (KSA7) of the soil. The KSAr was measured in the field and used to
characterize the infiltration rate for the proposed infiltration basin. KSAJ measurements were
performed at the proposed infiltration basin using a constant -head permeameter (Amoozemeter).
Based on conversations with the designer of the proposed infiltration basins, construction of the
basin would occur either at the current surface or potentially below the surface, no more than two
feet below current grade depending on testing results. Based on this information, and
information gathered during the auger borings, the KsAi measurements were performed around a
depth of 12 inches in order to estimate the infiltration rate at the new soil surface. In addition,
another test was conducted at 37 inches, as the soil profile displayed a change in texture around
30 inches.

RESULTS
Soil Type
All of the soil was in a natural state, and had similar properties to the previous investigation area.
The site was characterized by a sandy loam upper profile and a sandy clay loam subsoil. It is
identified as `Infiltration 3" in figure 2 and in the tables below.
Table 2 presents each boring with a soil series determination. Determination of soil series was
made through a comparison of soil boring descriptions to the Natural Resources Conservation
Service (MRCS) Official Series Description (OSD) for the soil series that were mapped by the
NRCS for this site.
Table 2 - Soil Series Determination and Depth to SHWT
Boring #
Soil Series Determination
SHWT Determination
inches below surface
Infiltration 1
Johnston
6
Infiltration IA
Blaney
24
Infiltration 2
Blaney
60+
Infiltration 3
Blaney
60+
Depth to Seasonal High Water Table
The depth to the seasonal high water table (SHWT) was noted at each boring based on
redoximorphic features, the presence of saturated soil, and best professional judgment.
Infiltration Rate
Saturated. hydraulic conductivity tests were performed at each of the proposed infiltration basin
sites and the results for each test are shown below in Table 3. Since soil is inherently non -
homogeneous, field tests can often misrepresent the aerial hydraulic conductivity of a soil. In
particular, field tests underestimate the saturated hydraulic conductivity of clayey soil and
overestimate it in sandy soils. As a result of this misrepresentation, a "moderation factor" is
suggested to convert point saturated hydraulic conductivity to aerial saturated hydraulic
conductivity for each proposed infiltration basin. Since the soil is typically sandy loam or sandy
clay loam, a moderation factor of 0.75 was used to correct for the potential of overestimating the
infiltration rate. I
Table 3 presents the saturated hydraulic conductivity for each infiltration basin as well as a
moderation factor to get an area infiltration rate for each proposed infiltration basin.
Table 3 - Results of Saturated Hydraulic Conductivity Tests
Soil Type
Test
Location
Test Depth
in
Measured
KSnr in/hr
75% of KSa-r
in/hr
Blaney
1
15
11.311
8.48
Blaney
2
14
19.103
14.33
Blaney
3a
37
10.205
7.65
Blaney
3b
12
32.676
24.51

As shown in Table 3, the proposed basin has an infiltration rate that is greater than the required
minimum of 0.52 inch/hour at both testing depths. This is consistent with the past testing of test
locations I and 2. Both instruments ran out of water within 30 — 40 minutes. Therefore, it is
apparent that the hydraulic conductivity of the soil should not limit its use for a stormwater
infiltration structure, so long as it is designed according to DWQ guidelines.
CONCLUSIONS
The findings presented herein represent TCG's professional opinion based on our site and soils
evaluation. This report is provided to assist in the application for the infiltration basin by
providing the soil information. North Carolina DWQ must issue the final permit. Any
concurrence with the findings in this report would be made at that time.

-. Komi;
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NRCS Soil Map
Indoor

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Figure
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Site Plan
Indoor Firing Range Site
S�,r
Group
Fort Bragg
As Shawn
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Job No.7429
Cumberland County, NC

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DEPARTMENT OF ENVIRONMENT
AND NATURAL RESOURCES
DIVISION OF ENVIRONMENTAL HEALTH
SOIL/SITE EVALUATION
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PROPERTY ID 4:
DATE OF EVALUATION: -/ 3G 0
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HYDRAULIC CONDUCTIVITY STUDY
Bragg Basin
Dale: 4/30/2009
Weather Condition: Sunny
Location: Bragg Basin
Temperature IF): 80
Number: 1
Horizon: B
1cm inches
Depth(inches): 15.0
SET UP
Target Water Level: 17.8 70
cm
Beginning Water Level: 7.6 3,0
Hole Depth (cm):
38.1
15.0
Ending Water Level: 7.6 30
Reference (cm):
+ 12,7
5.0
Head (cm):
- 17.8
7.0
CHT Tube(s) setting:
= 33.0
Hole diameter (cm): 5.0
Hole radius (r): 2.5 inches
Valve Setting:
I x 1
coefficient A: 0.003040
1-ON 2-ON
NOTE: Readings based on Ending Water Level
Coversion Factor (C. F.): 105.0
Water
Reading
change in
water level
Chamber
C. F.
clock
time (min)
Elapsed
(min)
Time
(hr)
O
(cm3mr)
K •
(cm/hr)
K
(in/hr)
K
gal/ft2/day
48.6
0,0
105.0
0,0
43.2
5.4
105.0
5.0
5.00
0.083
6804,0
20.6856
8A439
121,846
36.7
6.5
105.0
10.0
5.00
0.083
8190.0
24,8993
9:8029
146.667
30.5
6.2
105.0
15.0
5.00
0.083
7812.0
23.7501
9,3504
139.897
22.9
7.6
105.0
20.0
5.00
0.083
9576.0
29.1130
11.4618
171.487
18.5
4.4
105.0
23.0
3.00
0.050
9240,0
28.0915
11.0596
165.470
14
4.5
105.0
26.0
3.00
0.050
9450.0
28.7300
11.3110
169.231
9.5
4.5
105.0
29.0
3.00
0,050
9450.0
28.7300
11.3110
169,231
,5
4.5
1050
32.0
3.00
0.050
9450.0
28.7300
11.3110
169.231
0.5
4.5
105.0
35.0
3.00
0.050
9450.0
28.7300
11.3110
169,231
Final Ksat
28.730
11.311
169.231
HYDRAULIC CONDUCTIVITY STUDY
Bragg Basin
Dale: 4/30/2009
Location: Bragg Basin
Number: 2
Horizon: B
1cm
inches
Depth(inches): 14.0
SET UP
Target Water Level: 17.8
7.0
cm inches
Beginning Water Level: 7.6
3.0
Hole Depth (cm):
35.6
Ending Water Level: 7.6
3.0
Reference (cm):
+ 152
E7-1
Head (cm):
- 178
CHT Tube(s) setting:
= 33,0
Hole diameter (cm): FO
Hole radius (r): 2.5
Valve Setting:
7-7
coefficient A: 0.003040
1-ON 2-ON
NOTE: Readings based on Ending Water Level
Coversion Factor (C F.): 105.0
Water
Reading
change in
water level
Chamber
C. F.
clock
time (min)
Elapsed
(min)
Time
(hr)
O
(cm3/hr)
K
(cm/hr)
K
(in/hr)
K
gal/ft2/day
4T5
0.0
105.0
0.0
37.9
9.6
1050
5.0
5.00
0.083
12096.0
36.7743
14,4781
216,615
25.6
12,3
105,0
10.0
5.00
0.083
15498.0
47.1171
18,5500
277.538
18
7.6
105.0
130
300
0.050
15960.0
48.5217
19.1030
285.812
10A
7,6
105,0
16.0
3.00
0.050
15960.0
48,5217
19.1030
285.812
2.8
7.6
105,0
19.0
3.00
0.050
15960.0
48.5217
19.1030
285,812
Final Ksat
48.522
19.103
1 285.812

HYDRAULIC CONDUCTIVITY STUDY
Bragg Basin
Date: 7/7/2009
Location: Bragg Basin
Number: 3b
Horizon: E
-
CM
inches
Depth(inches): 12.0
SET UP
Target Water Level: 15.2
6.0
cm inche;_7
Beginning Water Level: 15.2
6,0
Hole Depth (cm):
30.5
12.0
Ending Water Level: 15.2
6.0
Reference (cm):
+ 15.2
6.0
Head (cm):
- 15.2
6.0
CHT Tube(s) setting:
= 30.5
Hole diameter (cm): 5.0
Hole radius (r): 2.5
Valve Setting:
coefficient A: OA01136
1-ON 2-ON
NOTE: Readings based on Ending Water Level
Coversion Factor ICY.): 105.0
Water
Reading
changein
water level,
Chamber
C.F.
clock
time (min)
Elapsed
(min)
Time
(hr)
Q
(cm3/hr)
K
(cm/hr)
K
(in/hr)
K
gal/ft2tday
47.7
0,0
105.0
8.0
27.2
20.5
105.0
13,0
5.00
0.083
25830.0
78.5285
30.9167
462,564
14.5
12.7
105.0
16.0
3,00
0.050
26670,0
81.0823
31.9222
477S07
102
4.3
105.0
17.0
1,00
0.017
27090,0
82,3592
32A249
485,128
5.7
4.5
105.0
18.0
1,00
0.017
28350.0
86,1899
33.9330
507.692
1.5
4.2
105.0
19.0
1.00
0.017
26460.0
80A439
31.6708
473.846
Final Ksat
82.998
32.676
1 488.889
HYDRAULIC CONDUCTIVITY STUDY
•
Bragg Basin
Date: 7(//2009
Location: Bragg Basin
Number: 3a
Horizon: at
1cm
inches
Deptb(inches): 37.0
SET UP
Target Water Level: 15.2
6.0
cm inches
Beginning Water Level: 15.2
6.O
Hole Depth (cm):
94.0 37.0 1
Ending Water Level: 15.2
6,0
Reference (cm):.
+ 102 4.0
Head (cm):
- 20.3 8.0
CHT Tube(s) setting:
= 83S
Hole diameter (cm): 5.0
'Hole radius (r): 2.5
Valve Setting:
x
coefficient A. 0,001136
1-ON 2-ON
NOTE: Readings based on Ending
Water Level
Coversion Factor (C.F.).
105.0
Water
Reading
change in
water level
Chamber
C.F.
clock
time (min)
Elapsed
(min)
Time
(hr)
Q
(cm3/hr)
K
(cm/hr)
K
(inMr)
K
gal/ft2/day
49.7
0.0
105,0
0.0
39.4
10.3
105.0
5,0
5.00
0.083
12978,0
39.4558
15.5338
232,410
32.6
6.6
105.0
10.0
5M
0,083
8316.0
25.2824
9.9537
148.923
26.5
6.3
105.0
15.0
5.00
0.083
79380
24.1332
9,5012 t
142.154
20.3
6.2
105.0
20.0
,5.00
0.083
78110
23.7501
9.3504
139.897
7.2
13.1
105,0
30.0
10.00
0,167
8253,0
25,0908
9.8783
147.795
4.5
2.7
105.0
32.0
2.00
0.033
8505.0
25S570
10.1799
152.308
1.7
2.8
105,0
34.O
2.00
0.033
88M0
26.8146
10.5569
157.949
Final Ksat
25.921
10.205
152.684