1239 State St-20190206Civil 16439 Briar Street
Omaha, NE 68136-4154
Solutions, LL.402-895-5633
1239 State Street Drainage Study
for Greg McIntosh
Blair, NE
(Revised February 6, 2019)
PROJECT UNDERSTANDING
Greg McIntosh is planning to construct a 62'x64' building at 1239 State Street in Blair, NE. The
lot size is 72'x 80' (0.13 acres).
The City of Blair, NE requires that storm water runoff from the 100 -year storm event on a
developed condition must not exceed the historic condition.
The drainage analysis for the existing site conditions was completed using the Win TR -55 Small
Watershed Hydrology program developed by the Natural Resources Conservation Service
(NRCS). Output data includes storm water runoff for the 10 -yr and 100 -yr storm events.
EXISTING SITE CONDITIONS
From the Natural Resources Conservation Service, it was determined that the soils in this area are
classified as Monona silt loam. The Hydrologic Soil Group for this soil is B. Drainage on the site
is generally from the southwest to the northeast. Storm runoff from the entire site will be used to
design the required storage.
Total area = 0.13 acres = 0.0002 sq. miles
Area = 0.13 acres CN = 79
Pavement/Roof Area = 0.064 acres
Grassed Area = 0.066
Q100 = 0.74 cfs
PROPOSED SITE CONDITIONS
Total area = 0.13 acres = 0.0002 sq. miles
Area = 0.13 acres CN = 92
Pavement/Roof Area = 0.110 acres
Grassed Area = 0.020
Q100 =1.02 cfs
www.civsolutions.com
The storage area will be created by digging a trench around the east, west, and south sides of the
proposed building. A berm will be needed on the east side of the building to maintain the required
trench depth. The top of the berm elevation should be 1178.33. This will allow excess storm
runoff to drain over the berm before reaching the building finish floor elevation of 1178.50.
The storage required for this site is 131 cubic feet.
Storage provide by the trench construction is 330 cubic feet.
ATTACHMENTS
No. l — Site Layout and Grading Plan Sheet (Revised 2/2019)
No. 2 — Soil Description of the Site
No. 3 - Drainage Analysis for Existing Site Conditions (7 pages) (Revised 2/2019)
No. 4 — Google Earth View of Existing Site Showing Current Buildings
No. 5 - Drainage Analysis for Proposed Site Conditions (7 pages) (Revised 2/2019)
No. 6 — Direct Runoff (Q) from the Existing 100 Yr. Storm (Revised 2/2019)
No. 7 — Direct Runoff (Q) from the Proposed 100 Yr. Storm (Revised 2/2019)
No. S — Detention Basin (Storage Volume Calculations) (Revised 2/2019)
www.civsolutions.com
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Soil Map --Washington County, Nebraska
Map Unit Legend
usoA Natural Resources Web Soil Survey 12/20/2018
M" Conservation Service National Cooperative Soil Survey Page 3 of 3
Map Unit Symbol
Map Unit Name
Acres in AOI
Percent of AOI
8083
Monona silt loam, terrace, 0 to
2 percent slopes
0.2
100.0%
Totals for Area of Interest
0.2
100.0%
usoA Natural Resources Web Soil Survey 12/20/2018
M" Conservation Service National Cooperative Soil Survey Page 3 of 3
Map Unit Description: Monona silt loam, terrace, 0 to 2 percent slopes ---Washington County,
Nebraska
Washington County, Nebraska
8083—Monona silt loam, terrace, 0 to 2 percent slopes
Map Unit Setting
National map unit symbol: 2sy5r
Elevation: 1,020 to 1,280 feet
Mean annual precipitation: 29 to 33 inches
Mean annual air temperature: 48 to 51 degrees F
Frost -free period: 145 to 165 days
Farmland classification: All areas are prime farmland
Map Unit Composition
Monona, terrace, and similar soils: 90 percent
Minor components: 10 percent
Estimates are based on observations, descriptions, and transects of
the mapunit.
Description of Monona, Terrace
Setting
Landform: Stream terraces
Landform position (two-dimensional): Summit
Landform position (three-dimensional): Tread
Down-slope shape: Convex
Across -slope shape: Linear
Parent material. Fine -silty loess
Typical profile
Ap - 0 to 7 inches: silt loam
A - 7 to 15 inches: silt loam
Bw - 15 to 30 inches: silt loam
C - 30 to 79 inches: silt loam
Properties and qualities
Slope: 0 to 2 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: Low
Capacity of the most limiting layer to transmit water (Ksat):
Moderately low to moderately high (0. 14 to 1.42 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum in profile: 12 percent
Salinity, maximum in profile: Nonsaline to very slightly saline (0.0
to 2.0 mmhos/cm)
Available water storage in profile: Very high (about 12.9 inches)
Interpretive groups
Land capability classification (irrigated): 1
Land capability classification (nonirrigated): 1
usgn Natural Resources Web Soil Survey 12/20/2018
WM Conservation Service National Cooperative Soil Survey Page 1 of 2
Map Unit Description: Monona silt loam, terrace, 0 to 2 percent slopes ---Washington County,
Nebraska
Hydrologic Soil Group: B
Ecological site: Deep Loess Upland Prairie (R107BY002MO)
Hydric soil rating: No
Minor Components
Corley, terrace
Percent of map unit: 10 percent
Landform: Stream terraces
Landform position (two-dimensional): Toeslope
Landform position (three-dimensional): Dip
Down-slope shape: Concave
Across -slope shape: Concave
Ecological site: Wet Upland Depression Prairie (R107BY0221A)
Hydric soil rating: Yes
Data Source Information
Soil Survey Area: Washington County, Nebraska
Survey Area Data: Version 17, Sep 12, 2018
usDA Natural Resources Web Soil Survey 12/20/2018
Conservation Service National Cooperative Soil Survey Page 2 of 2
Attachment No. 3
Drainage Analysis for Existing Site Conditions
7 Pages
WinTR-55 Current Data Description
Identification Data ---
User:
Dan
Date:
2/6/2019
Project:
Greg McIntosh
Units:
English
SubTitle:
1239 State Street, Blair,
NE (Existing Site)
Areal Units:
Acres
State:
Nebraska
County:
Washington
Filename:
F:\Civil Solutions\Greg McIntosh - Blair\Existing Site Drainage.w55
--- Sub -Area Data
Name Description Reach Area(ac) RCN Tc
------------ -------------
A1 Outlet 0.13 79 .158
Total area: .13 (ac)
--- Storm Data --
Rainfall Depth by Rainfall Return Period
2 -Yr 5 -Yr 10 -Yr 25 -Yr 50 -Yr 100 -Yr 1 -Yr
(in) (in) (in) (in) (in) (in) (in)
----------------------------------------------------------------------------
3.0 3.87 4.6 5.25 5.95 6.55 2.42
Storm Data Source: Washington County, NE (NRCS)
Rainfall Distribution Type: Type II
Dimensionless Unit Hydrograph: <standard>
WinTR-55, Version 1.00.10 Page 1 2/6/2019 11:16:14 AM
Dan Greg McIntosh
1239 State Street, Blair, NE (Existing Site)
Washington County, Nebraska
Storm Data
Rainfall Depth by Rainfall Return Period
2 -Yr 5 -Yr 10 -Yr 25 -Yr 50 -Yr 100 -Yr 1 -Yr
(in) (in) (in) (in) (in) (in) (in)
----------------
3.0 3.87 4.6 5.25 5.95 6.55 2.42
Storm Data Source: Washington County, NE (NRCS)
Rainfall Distribution Type: Type II
Dimensionless Unit Hydrograph: <standard>
WinTR-55, Version 1.00.10 Page 1 2/6/2019 11:16:14 AM
Dan Greg McIntosh
1239 State Street, Blair, NE (Existing Site)
Washington County, Nebraska
Watershed Peak Table
Sub -Area
Peak
Flow by
Rainfall
Return Period
or Reach
10 -Yr
25 -Yr
50 -Yr
100 -Yr
Identifier
(cfs)
(cfs)
(cfs)
(cfs)
-------------------------------------------------------
SUBAREAS
Al
0.44
0.54
0.65
0.74
REACHES
OUTLET 0.44 0.54 0.65 0.74
WinTR-55, Version 1.00.10 Page 1 2/6/2019 11:16:14 AM
Dan Greg McIntosh
1239 State Street, Blair, NE (Existing Site)
Washington County, Nebraska
Hydrograph Peak/Peak Time Table
Sub -Area Peak Flow and Peak Time (hr) by Rainfall Return Period
or Reach 10 -Yr 25 -Yr 50 -Yr 100 -Yr
Identifier (cfs) (cfs) (cfs) (cfs)
(hr) (hr) (hr) (hr)
----------------------------------------------------------------------
SUBAREAS
Al 0.44 0.54 0.65 0.74
11.98 11.97 11.97 11.97
REACHES
OUTLET 0.44 0.54 0.65 0.74
WinTR-55, Version 1.00.10 Page 1 2/6/2019 11:16:14 AM
Dan Greg McIntosh
1239 State Street, Blair, NE (Existing Site)
Washington County, Nebraska
Sub -Area Summary Table
Sub -Area Drainage Time of Curve Receiving Sub -Area
Identifier Area Concentration Number Reach Description
(ac) (hr)
--------------------------------------------------------------------------------
Al .13 0.158 79 Outlet
Total Area: .13 (ac)
WinTR-55, Version 1.00.10 Page 1 2/6/2019 11:16:14 AM
Dan Greg McIntosh
1239 State Street, Blair, NE (Existing Site)
Washington County, Nebraska
Sub -Area Time of Concentration Details
Sub -Area Flow Mannings's End Wetted Travel
Identifier/ Length Slope n Area Perimeter Velocity Time
(ft) (ft/ft) (sq ft) (ft) (ft/sec) (hr)
Al
SHEET 99 0.0240 0.150
SHALLOW 18 0.0240 0.025
0.156
0.002
Time of Concentration .158
WinTR-55, Version 1.00.10 Page 1 2/6/2019 11:16:14 AM
Dan
Sub -Area
Identifier
Al
Greg McIntosh
1239 State Street,
Blair, NE
(Existing Site)
Washington
County, Nebraska
Sub -Area Land Use
and Curve
Number Details
Hydrologic
Sub -Area
Land Use
Soil
Area
Group
(ac)
---------------------------------------------------------------
Open space; grass cover >
750
(good) B
.066
Paved parking lots, roofs,
driveways
B
.064
Total Area / Weighted Curve
Number
.13
Curve
Number
61
98
79
WinTR-55, Version 1.00.10 Page 1 2/6/2019 11:16:14 AM
04
Attachment No. 5
Drainage Analysis for Proposed Site Conditions
7 Pages
WinTR-55 Current Data Description
--- Identification Data
User:
Dan
Date:
2/6/2019
Project:
Greg McIntosh
Units:
English
SubTitle:
1239 State Street, Blair,
NE (Proposed Site)
0.1
Total area:
.13 (ac)
Areal Units:
Acres
State:
Nebraska
County:
Washington
--
Filename:
F:\Civil Solutions\Greg McIntosh - Blair\Proposed Site Drainage.w55
Sub -Area Data
Name
Description
Reach
Area(ac) RCN
Tc
------------------------------------------------------------------------------
A1
Outlet
0.13 92
0.1
Total area:
.13 (ac)
---
Storm Data
--
Rainfall
Depth
by Rainfall
Return Period
2 -Yr
5 -Yr
10 -Yr
25 -Yr
50 -Yr 100 -Yr
1 -Yr
(in)
--------------------------------------------------------------------------------
(in)
(in)
(in)
(in) (in)
(in)
3.0
3.87
4.6
5.25
5.95 6.55
2.42
Storm Data Source: Washington County, NE (NRCS)
Rainfall Distribution Type: Type II
Dimensionless Unit Hydrograph: <standard>
WinTR-55, Version 1.00.10 Page 1 2/6/2019 11:26:00 AM
Dan Greg McIntosh
1239 State Street, Blair, NE (Proposed Site)
Washington County, Nebraska
Storm Data
Rainfall Depth by Rainfall Return Period
2 -Yr 5 -Yr 10 -Yr 25 -Yr 50 -Yr 100 -Yr 1 -Yr
(in) (in) (in) (in) (in) (in) (in)
--------------------------------------------------------------------------------
3.0 3.87 4.6 5.25 5.95 6.55 2.42
Storm Data Source: Washington County, NE (NRCS)
Rainfall Distribution Type: Type II
Dimensionless Unit Hydrograph: <standard>
I
WinTR-55, Version 1.00.10 Page 1 2/6/2019 11:26:00 AM
Dan Greg McIntosh
1239 State Street, Blair, NE (Proposed Site)
Washington County, Nebraska
Watershed Peak Table
Sub -Area
Peak
Flow by
Rainfall
Return Period
or Reach
10 -Yr
25 -Yr
50 -Yr
100 -Yr
Identifier
(cfs)
(cfs)
(cfs)
(cfs)
-----------------------------------------------------------
SUBAREAS
Al
0.69
0.80
0.92
1.02
REACHES
OUTLET 0.69 0.80 0.92 1.02
WinTR-55, Version 1.00.10 - Page 1 2/6/2019 11:26:00 AM
Dan Greg McIntosh
1239 State Street, Blair, NE (Proposed Site)
Washington County, Nebraska
Hydrograph Peak/Peak Time Table
Sub -Area Peak Flow and Peak Time (hr) by Rainfall Return Period
or Reach 10 -Yr 25 -Yr 50 -Yr 100 -Yr
Identifier (cfs) (cfs) (cfs) (cfs)
(hr) (hr) (hr) (hr)
----------------------------------------------------------------------
SUBAREAS
Al 0.69 0.80 0.92 1.02
11.93 11.93 11.93 11.93
REACHES
OUTLET 0.69 0.80 0.92 1.02
WinTR-55, Version 1.00.10 Page 1 2/6/2019 11:26:00 AM
Dan Greg McIntosh
1239 State Street, Blair, NE (Proposed Site)
Washington County, Nebraska
Sub -Area Summary Table
Sub -Area Drainage Time of Curve Receiving Sub -Area
Identifier Area Concentration Number Reach Description
(ac) (hr)
--------------------------------------------------------------------------------
Al .13 0.100 92 Outlet
Total Area: .13 (ac)
WinTR-55, Version 1.00.10 Page 1 2/6/2019 11:26:00 AM
Dan Greg McIntosh
1239 State Street, Blair, NE (Proposed Site)
Washington County, Nebraska
Sub -Area Time of Concentration Details
Sub -Area
Flow
Mannings's
Identifier/
Length
Slope
n
(ft)
(ft/ft)
-----------------------------------------
Al
SHEET
40
0.4167
0.011
SHALLOW
62
0.0050
0.025
SHALLOW
65
0.0100
0.050
End Wetted Travel
Area Perimeter Velocity Time
(sq ft) (ft) (ft/sec) (hr)
-------------------------------------
0.003
0.012
0.011
Time of Concentration 0.1
WinTR-55, Version 1.00.10 Page 1 2/6/2019 11:26:00 AM
Dan
Sub -Area
Identifier
Al
Greg McIntosh
1239 State Street, Blair, NE (Proposed Site)
Washington County, Nebraska
Sub -Area Land Use and Curve Number Details
Hydrologic
Land Use Soil
Group
----------------------------------------------------
Open space; grass cover > 75% (good) B
Paved parking lots, roofs, driveways B
Total Area / Weighted Curve Number
Sub -Area
Area
(ac)
.02
.11
.13
Curve
Number
61
98
92
WinTR-55, Version 1.00.10 Page 1 2/6/2019 11:26:00 AM
ATTACHMENT NO. 8
F% um 6-1 %pproxim ;te de-te-otxnm b,' si:ti muting for rairdh)l types L I.4, Ii. and 'tH STORAGE VOLUME CALCULATIONS
:5
0.202
" 0.726
.1 .2 .3 .4
.$
Peak o>ittlow discharge
Peak inflow discharge qi
rf-? (210 -1I -'CF -i5. and F-rL. June ,30)