HomeMy WebLinkAboutCC - Storm Drainage Calcs DRAINAGE CALCULATIONS
FOR
SPRINGDAY SUBDIVISION N0.1
MERIDIAN, IDAHO
April 8, 2026
ENGINEERING SOLUTIONS, LLP
1029 N. Rosario Street, Suite 100
Meridian, Idaho 83642
(208) 938 -0980
SS�ONAL FN
20305
✓� 4lF 0F
SyvA H.
Job Number: 251114
Springday No.l
Drainage Calculations Report
The project is located in the SW 1/4 of the SE 1/4 of Section 33, T.4N., R.1 W.,
B.M., Meridian, Ada County, Idaho. Springday No.l is comprised of 52
single family lots and 11 common lots on approximately 14.0+/- acres. The
storm drainage from this project will be intercepted by drop inlets, will flow
into sand and grease traps and then into seepage beds.
Assumptions used for this drainage report are as follows:
1. Rational Equation used to estimate storm runoff(Q = CIA)
2. SCS: TR-55 Method used to determine Time of Concentration (Tc)
with a minimum of 10 minutes.
3. A weighted Coefficient of Runoff C of 0.50 was used for single
family large lots.
The rational method was used to determine the peak discharge. This
method uses a "C" value, Time of Concentration (Tc) calculated by SCS
TR-5 5 methods and rainfall Intensity Duration Frequency (IDF) curves
from Appendix A from the ACHD Stormwater Manual 2017. The rainfall
intensity is determined from the IDF curve where "I" is selected at the
calculated Tc and the 100-year return.
Springday No. 1 is divided into 15 runoff collection areas. The contributing
areas are depicted on the Drainage Plan.
The peak discharge is used to determine the capacity of the pipes and drop
inlet. Time of Concentration was determined using ACHD's Stormwater
Design Spreadsheet. Calculated TC is used to select the "I" in the peak
discharge calculations. The volume calculations were determined by using
ACHD's Stormwater Design Spreadsheet.
Proposed Drainage
The proposed drainage system improvements consist of drop inlets, sand
and grease traps, a storm pipe network and seepage beds.
Areas 1 and 2 will be picked up in drop inlets and piped into a manhole. From
the manhole stormwater is piped east in a 12" overflow pipe to 5' into seepage
bed 1.1 and then connects to a 12" perforated pipe that extends through the bed. A
second 12" pipe from the manhole extends north to a 1000 —gallon sand and
grease trap. From the sand and grease trap an 18" pipe extends east 5' into
seepage bed 1.1 and then connects to an 18" top only perforated pipe that extends
through the seepage bed. The seepage bed has 1.5' of filter sand between the
water quality storm side and the 100-year storage. The seepage bed is designed be
built at high groundwater.
Areas 3 and 4 will be picked up in drop inlets and piped into a manhole. From
the manhole stormwater is piped south in a 12" overflow pipe to 5' into seepage
bed 1.2 and then connects to a 12" perforated pipe that extends through the bed. A
second 12" pipe from the manhole extends east to a 1000 —gallon sand and
grease trap. From the sand and grease trap an 18" pipe extends south 5' into
seepage bed 1.2 and then connects to an 18" top only perforated pipe that extends
through the seepage bed. The seepage bed has 1.5' of filter sand between the
water quality storm side and the 100-year storage. The seepage bed is designed be
built at high groundwater.
Areas 5 and 6 will be picked up in drop inlets and piped into a manhole. From
the manhole stormwater is piped west in a 12" overflow pipe to 5' into seepage
bed 1.3 and then connects to a 12"perforated pipe that extends through the bed. A
second 12" pipe from the manhole extends south to a 1000 —gallon sand and
grease trap. From the sand and grease trap an 18" pipe extends west 5' into
seepage bed 1.3 and then connects to an 18" top only perforated pipe that extends
through the seepage bed. The seepage bed has 1.5' of filter sand between the
water quality storm side and the 100-year storage. The seepage bed is designed be
built at high groundwater.
Areas 7 and 8 will be picked up in drop inlets and piped into a manhole. From
the manhole stormwater is piped east to a second manhole where it is piped north
in a 12" overflow pipe to 5' into seepage bed 1.4 and then connects to a 12"
perforated pipe that extends through the bed. A second 12" pipe from the
manhole extends east to a 1000 — gallon sand and grease trap. From the sand and
grease trap an 18" pipe extends north 5' into seepage bed 1.4 and then connects to
an 18"top only perforated pipe that extends through the seepage bed. The
seepage bed has 1.5' of filter sand between the water quality storm side and the
100-year storage. The seepage bed is designed be built at high groundwater.
Areas 9 and 10 will be picked up in drop inlets and piped into a 1000 - gallon
sand and grease trap. An 18" pipe from the sand and grease trap extends west 5'
into seepage bed 1.5. An 18" top only perforated pipe extends through the
seepage bed. The seepage bed has 1.5' of filter sand below it. The seepage bed is
designed to have 3' of separation from high groundwater.
Area 11 will be picked up in a drop inlet and piped east into a manhole. Area 12
will be picked up in a drop inlet and piped south into the manhole where it will
combine with area 11 and be piped south to a drop inlet. Areas 11 and 12 will
combine with area 13 in the drop inlet and then piped into a 1000 - gallon sand
and grease trap. An 18"pipe from the sand and grease trap extends west 5' into
seepage bed 1.6. An 18" top only perforated extends through the seepage bed.
The seepage bed has 1.5' of filter sand below it. The seepage bed is designed to
have 3' of separation from high groundwater.
Areas 14 and 15 will be picked up in drop inlets and piped into a 1000 - gallon
sand and grease trap. An 18" pipe from the sand and grease trap extends east 5'
into seepage bed 1.7. An 18" top only perforated pipe extends through the
seepage bed. The seepage bed has 1.5' of filter sand below it. The seepage bed is
designed to have 3' of separation from high groundwater.
Seepage Beds
The seepage beds are sized for the 100-year storm per ACHD Stormwater
Design Spreadsheet. The seepage beds use clean drain rock wrapped in filter
fabric to facilitate drainage, top half perforated pipes, perforated pipes and
1.5' of sand underneath the clean drain rock (1.5' between the water quality
and 100-year section for sideways beds). The seepage beds also contain a
monitoring well inside the beds and one outside the beds. The seepage beds
were sized using a percolation rate of 1"/hr to 2"/hr through the bottom of
the beds. The seepage bed drains 90% of the 100-year storm within 48
hours. The beds were designed to have a minimum of 3' of separation from
high groundwater based on the geotechnical report provided by GEOTEK.
yo eo 3 �o §0 9 a Ci
"'oo 080 oe� 0 00 y� �m
E2g
888 `R;e 14 51S$ 88« cm 2 !.e e�38 GS R ea S8� gA 8 8a r8", :8 �dlFo Q
to; a a� �z$ a� to; .0 pu a� �zWa
e � e y a yz
o$ R9 `.98 T�8 Sam 819 8 R9 :8� a$ 889 88 �.$ 88r S83 �,� gall
AW
rya A ga S8p V 4 RPT 9Pf9 82 9Q
yo
�m 882 ��m MM.2 a �m W C m$
N �78
9 I .a.am ass m � zsR
ay �mm Hy gN ��
S3 53 S 53 SS� S Si S3 53 53 53
o $oo $88 a,- 8 8 888 8818 81, RPR ° � s.N 888 R boo ebd o
$88 rp
8�0a�o duo 8 a y�g
% V :eaa 889 80 8: � 888 ^.& $ r8A `rRm � S8� �8e v.
N - #
.- a n ♦ tit-i���a��U
8 < a O c v�3 m®9 i
/ r
sod
oar
-- -- ,- —
—
.
I ��µ
it
1 0 N 1,11 I I
I
Nry�=
I I II - yli ' II�f I�ICD I III 1111 ° I I I I i
€ I I' e li II IIIII I ,- _ _ 11�4'II IpIJ Z p = loll l,l 17
I — \
If
fa-
if
— —
L
It I a $$^ @ �_.' °�a lellkl' rII -II'°.IIJ aihllll= IP.. I `3 K n
�'
—
i � 1+u
I•.�' II�I III I - = _ .::µO II r _ - ,P '
--�----
III
IIII �I' - flit I
4 I�--
:I IF
EYi��
fl _
°I l i II� •III n CM,�
- / h IIIII 1,I c
O @ Jd
'I I cn III�I T- tt z
it m
i I I � 'I it I I $ � ,. - � _ •. 1� z
If
Q li i cc &' g
CD
01
Di FTP
I II I NI � .. I � aL
3 p r, 8d I I 13
I -
,a �I
.a as
z ate.rs al
�. -- N"1- -- - q •__ -—-—-—-
w
04 coM O CY)O w r N O N N N M m M_ V N
p p j U O U') M U7 V' N M U) U7 N O M co ON� M W
II II II r N r Cl) N N '�
_ _ 7
— U
U
0)
w h wU- m 7 M Cl) O V 0) O m Cl) m N m U) V O m(O m O
(a U O co m0 co CC co V N 00 co O 0 (O CO V (O'IT m N Ln CO
C U) U) �.., M r m N cn r (`') �n M m r m r CO U) r
U
Q)
ca
O O O
U7 U) U)
O O O
II II II O)
U U U w N O N O CO U) 0000 co N ')ON r U) (O ('M O N IT r U7
W U m N co N co N O O r V Lo r CO m (M V*
cn U) 0 r N cr N (0 co m r- O � N r Cl) r N N N �Y
J E E E V
W Q Q Q
Q N �
2 � r
# «
CO to (0 m U) CO CO m 'IT V f.- CO O M 00(n V' �00 COQ co (V o w Lq U) m U) m 0? O V I? U)V O V'r O O U7 N
2 m Q CJ o O O O O O r 04 Cl) oo O Oo0 C)0
Q Qu
O n
N N �
> > >
CO V M N 7 CD r CD m M O toLn N O CD a) V' U) Il-
M co (O <}' O O r U7 O O m M N O M r M r M �
O O O O O r C) r r O r O O O O O O O O O O
M M M M V OD O N ) Cl)- O U7 U) v O r V LC) OD U)IT m
w r r N . N M rV: U) V M I- r O N r O r N r r N
O O O O O O O O O O O O O O O O O O O O O O X
U)
N
co
O
N
JI
0
c m 00 M co W OO a0 C2 W W OO OO OO CO CO OO O OO O 00
N N N N N N N r N N N N N N N N N N N N N UI
V
N
O3 O7 O N N r r V' C' N N N N N r N N N
LL LL L.L (O V O V tt r V V O M CO CO CO V rt O CO M
0) N N
m m m
C C C
U co U
O O O
U) U) U)
O O O
II II II
U U U Cl) Cl) M M Cl) Cl) Cl) Cl) M M M M
_ CO U') In (O (n U) (n '7 (n UJ (n CO CO CO CO CO(n (n CO CO CO
rn N U O O O O O O O O O O O O O O O 0 0 0 O O O O
E E E
y N
Q Q Q
Q
Q o C
0 0 0 O O O O O O O O O O O O
O Q o (o r r 00 O O O O O O O O
O (D Nr 'r (O r U) OO(o co O O m m M r` r-
J Lr)O O H �_ N U1 U) N U) ui I� r r m m m 64 V r 0 U) U7 O V' -'rLL (O r N N
Y O O 11 0 E
Q II v o
a
f- 00 r N O V V O N N U7 m r-N CO U) O U) U)
C _ _ _
x V '7 t coU) m I� m O U7 m 00 �M I- M r U) O U)V O)
Q CD O R O O O r O r N r N 0 0 0 O O O r O O O
N M
O a*
Z
O O O O o
O LO co Z Z Z Z Z Z Z
•y N N Z -o -o -a a -o
'> .. Q Z N m M V' m U) O m f` 00
LL m m O m r N M m U7 m
'Q O m N 4) N N O N N
7 Z m N (o (m0 OJ CO O7 co
>+ 0
1II U U U U U U
C
'C
!Z
ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These
calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted.
Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab)
User input in yellow cells.
1 Project Name SPRINGDAY SUBDIVISION BED 1.1
2 Is area drainage basin map provided? YES
(map must be included with stormwater calculations)
3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100
4 Enter number of storage facilities(25 max)
Click to Show More Subbasins ❑
Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin
1 Subbasin 2 3 4 5 6 7 8 9 10
5 Area of Drainage Subbasin(SF or Acres) Acres 0.41 0.47
Acres 0.88
6 Determine the Weighted Runoff Coefficient(C) 0.50 0.50
C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.50
7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate
10 Min_ Estimated Runoff Coefficients for Various Surfac
Type of Surface Runoff Coefficients"
Business
Hydraulic Downtown areas 0.70-0.95
Radius Flow Flow Urban neighborhoods 0.50-0.70
Intercept A/Wet Velocity V Time Residential
ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Single Family 0.35-0.50
Multi-family 0.60-0.75
Segment 1:Pipe Flow Residential(rural) 0.25-0.40
a Apartment Dwelling Areas 0.70
Industrial and Commercial
Light areas 0.80
Segment 2:Gutter Shallow Concentrated Flow Heav
y areas 0.90
b 0.006 0.619 372 1.5 4.1 Parks,Cemeteries 0.10-0.25
Playgrounds 0.20-0.35
Segment 3:Overland Sheet Flow By TR-55,<300-ft Railroad yard areas 0.20-0.40
c 0.020 39 0.240 3.6 11.0
Computed Tc= 15.1
User-Entered Tc= 15.1
8 Determine the average rainfall intensity(i)from IDF Curve based on i 2.18 in r
y Calculate the Post-Development peak discharge(QPeak) Qp aA 0.96 cfs
10 Calculate total runoff vol(V)(for sizing primary storage) V 1,521 ft
V=Ci(Tc=60)Ax3600
11 Calculate Volume of Runoff Reduction Vrr
Enter Percentile Storm 1(95th percentile=0.60 in) 95th 0.60 in
Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) V„ 950 ft'
12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs
13 Volume Summary
Surface Storage:Basin Unimproved areas 0.10-0.30
Basin Forebay V 152 ft' Streets
Asphalt 0.95
Primary Treatment/Storage Basin V 1,369 ft Concrete 0.95
Subsurface Storage Brick 0.95
Volume Without Sediment Factor(See BMP 20 Tab) V 1,521 ft' Roofs 0.95
Gravel 0.75
Fields:Sandy soil Soil Type
Slope A B C D
Flat:0-2% 0.04 0.07 0.11 0
Average:2-6% 0.09 0.12 0.15 0
Steep:>6% 0.13 0.18 0.23 0
Adapted from ASCE
\\ES-1\Projects\2025\251114\Correspondence\Calcs\Storm Drain Calc-BED 1.1.xlsm 4/8/2026,1:45 PM
Version 10.5,November 2018
ACHD Calculation Sheet for Sand/Grease Traps
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the
Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must
result in facilities that meet or exceed these calculations in order to be accepted.
�u r 77
User input in yellow cells.
1 Project Name SPRINGDAY SUBDIVISION BED 1.1
2 Enter number of Sand/Grease Traps(25 max) 1
Number of Peak Flow Baffle Throat Velocity Is the
Vault Size Spacing width Area(ft2) 0.5 fps Velocity
S/G Traps Q-cfs
inch inch max. ok?
1000 G 1 0.96 20 48 6.67 0.14
Reference for Throat widths(inch)
ADS
Boise Lar-ken WQU,
Vault BMP 16
1000 G 48.0 50.5 n/a
1500 G 60.0 61.5 n/a
WQU1000 n/a n/a 60
WQU1500 n/a n/a 60
\\ES-1\Projects\2025\251114\Correspondence\Calcs\Storm Drain Calc-BED 1.1.x1sm 4/8/2026, 1:45 PM
Version 10.0, May 2018
ACHD Calculation Sheet for Sizing Vertical Sand Filters
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's
calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that
meet or exceed these calculations in order to be accepted.
Note this spreadsheet pulls information from the"Peak QV"tab
Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab)
User input in yellow cells.
Project Name SPRINGDAY SUBDIVISION BED 1.1
Enter number of Seepage Beds(25 max) 1
Design Storm Unlined Side 100 'Q,V'
Design Storm Lined Side —2 Q,V
rQV TR55
Weighted Runoff Coefficient C 0.50 Link to:
Area A(Acres) 0.88 acres
Approved discharge rate(if applicable) 0.00 cfs
100 Year Storm Volume V 1,521 ft3
2 Year Storm Volume V2 412 ft3
Width of Unlined Side W 14.1 15 ft
Width of Lined Side W2 4.0
Set Total Design Depth of All Drain Rock D 4.5 ft
Rock Only,Do Not Include Filter Sand Depth c D2 4.5 ft
Void Ratio of Drain Rock Voids 0.4
0.4 for 1.5"-2"drain rock and 3/4"Chips
Design Infiltration Rate(8 in/hr max) Perc 1.10 in/hr
Size of Perf Pipe(Perf 3600) Dia pipe 12 in
Design Length of Unlined Side L 60
Design Length of Lined Side L 57 60 ft
Time to Drain Unlined Side 44.2 hours
90%volume in 48-hours minimum
Length of WQ&Overflow Perf Pipes 60 ft
Perf Pipe Checks.Qperf>=Qpeak;
where Qperf=CdxAxV(2xgxH)
ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These
calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted.
7.
Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab)
User input in yellow cells.
1 Project Name SPRINGDAY SUBDIVISION BED 1.2
2 Is area drainage basin map provided? YES
(map must be included with stormwater calculations)
3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100
4 Enter number of storage facilities(25 max)
Click to Show More Subbasins ❑
Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin
1 Subbasin 2 3 4 5 6 7 8 9 10
5 Area of Drainage Subbasin(SF or Acres) Acres 0.51 0.91
Acres 1.42
6 Determine the Weighted Runoff Coefficient(C) 0.50 0.50
C=[(C1xA1)+(C2xA2)+(CnxAn)j/A Weighted AvgJ 0.50
7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate
10 Min. Estimated Runoff Coefficients for Various Surfac
Type of Surface Runoff Coefficients"
Business
Hydraulic Downtown areas 0.70-0.95
Radius Flow Flow Urban neighborhoods 0.50-0.70
Intercept A/Wet Velocity V Time Residential
ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) single Family 0.35-0.50
Multifamily 0-60-0.75
Segment 1:Pipe Flow Residential(rural) 0.25-0.40
a Apartment Dwelling Areas 0.70
Industrial and Commercial
Light areas 0
Segment 2:Gutter Shallow Concentrated Flow Heav
y areas 0.-90
90
b 0.007 0.619 392 1.6 4.0 Parks,Cemeteries 0.10-0.25
Playgrounds 0.20-0.35
Segment 3:Overland Sheet Flow By TR-55,<300-ft Railroad yard areas 0.20-0.40
c 0.020 39 0.240 3.6 11.0
Computed Tc= 15.0
User-Entered Tc= 15.0
8 Determine the average rainfall intensity(i)from IDF Curve based on i 2.18 in r
9 Calculate the Post-Development peak discharge(QPeak) QP.k 1.55 cfs
10 Calculate total runoff vol(V)(for sizing primary storage) V 2,454 ft
V=Ci(Tc=60)Ax3600
11 Calculate Volume of Runoff Reduction Vrr
Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in
Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 1,534 ft
12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs
13 Volume Summary
Surface Storage:Basin Unimproved areas 0.10-0.30
Basin Forebay V 245 W Streets
Asphalt 0.95
Primary Treatment/Storage Basin V 2,208 ft Concrete 0.95
Subsurface Storage Brick 0.95
Volume Without Sediment Factor(See BMP 20 Tab) V 2,454 ft' Roofs 0.95
Gravel 0.75
Fields:Sandy soil Soil Type
Slope A B C 0
Flat:0-2% 0.04 0.07 0.11 0
Average:2-6% 0.09 0.12 0.15 0
Steep:>6% 0.13 0.18 0.23 0
Adapted from ASCE
\\ES-1\Projects\2025\251114\Correspondence\Calcs\Storm Drain Calc-BED 1.2.xism 4/8/2026,1:47 PM
Version 10.5,November 2018
ACHD Calculation Sheet for Sand/Grease Traps
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the
Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must
result in facilities that meet or exceed these calculations in order to be accepted.
yUT�r�. r.t �.be s u i. �
s-
User input in yellow cells.
1 Project Name SPRINGDAY SUBDIVISION BED 1.2
2 Enter number of Sand/Grease Traps(25 max) 1
Number of Peak Flow Baffle Throat Velocity Is the
Vault Size Spacing width Area(ft2) 0.5 fps Velocity
S/G Traps Q-cfs inch inch max. ok?
1000 G 1 1.55 20 48 6.67 0.23
Reference for Throat widths(inch)
ADS
Boise Lar-ken WQU,
Vault BMP 16
1000 G 48.0 50.5 n/a
1500 G 60.0 61.5 n/a
WQU1000 n/a n/a 60
WQU 1500 n/a n/a 60
\\ES-1\Projects\2025\251114\Correspondence\Calcs\Storm Drain Calc-BED 1.2.xlsm 4/8/2026, 1:47 PM
Version 10.0, May 2018
ACHD Calculation Sheet for Sizing Vertical Sand Filters
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's
calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that
meet or exceed these calculations in order to be accepted.
Note this spreadsheet pulls information from the"Peak QV"tab
Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab)
User input in yellow cells.
Project Name SPRINGDAY SUBDIVISION BED 1.2
Enter number of Seepage Beds(25 max) 1
Design Storm Unlined Side 100 'Q,V'
Design Storm Lined Side 2 L Q,y
QV TR55
Weighted Runoff Coefficient C 0.50 Link to:
Area A(Acres) 1.42 acres
Approved discharge rate(if applicable) 0.00 cfs
100 Year Storm Volume V 2,454 ft3
2 Year Storm Volume V2 665 ft3
Width of Unlined Side W 14.8 15 ft
Width of Lined Side W2 4.0
Set Total Design Depth of All Drain Rock D 5.0 ft
Rock Only,Do Not Include Filter Sand Depth c D2 5.0 ft
Void Ratio of Drain Rock Voids 0.4
0.4 for 1.5"-2"drain rock and 3/4"Chips
Design Infiltration Rate(8 in/hr max) Perc 1.30 in/hr
Size of Perf Pipe(Perf 3600) Dia pipe 12 in
Design Length of Unlined Side L 83
Design Length of Lined Side L 83 83 ft
Time to Drain Unlined Side 41.5 hours
90%volume in 48-hours minimum
Length of WQ&Overflow Perf Pipes 83 83 ft
Perf Pipe Checks.Qperf>=Qpeak;
where Qperf=CdxAxV(2xgxH)
ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These
calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted.
Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab)
User input in yellow cells.
1 Project Name SPRINGDAY SUBDIVISION BED 1.3
2 Is area drainage basin map provided? YES
(map must be included with stormwater calculations)
3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100
4 Enter number of storage facilities(25 max)
Click to Show More Subbasins ❑
Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin
1 Subbasin 2 3 4 5 6 7 8 9 10
5 Area of Drainage Subbasin(SF or Acres) Acres 0.70 1.94
Acres 2.64
6 Determine the Weighted Runoff Coefficient(C) 0.50 0.50
C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.50
7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 user Calculate
10 Min. Estimated Runoff Coefficients for Various Surfac
Type of Surface Runoff Coefficients"
Business
Hydraulic Downtown areas 0.70-0.95
Radius Flow Flow Urban neighborhoods 0.50-0.70
Intercept A/Wet Velocity V Time Residential
ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Single Family 0.35-0.50
Multi-family 0.60-0.75
Segment 1:Pipe Flow Residential(rural) 0.25-0.40
a Apartment Dwelling Areas 0.70
Industrial and Commercial
Segment 2:Gutter Shallow Concentrated Flow Hght areas 0.90
vy areas .0
b 0.006 0.619 477 1.5 5.1 Parks,Cemeteries 0.10-0.25
Playgrounds 0.20-0.35
Segment 3:Overland Sheet Flow By TR-55,<300-ft Railroad yard areas 0.20-0.40
c 0.020 64 0.240 3.9 16.3
Computed Tc= 21.4
User-Entered Tc= 21.4
8 Determine the average rainfall intensity(i)from IDF Curve based on i 1.81 in r
9 Calculate the Post-Development peak discharge(QPeak) Qpeak 2.39 cfs
10 Calculate total runoff vol(V)(for sizing primary storage) V 4,562 ft
V=Ci(Tc=60)Ax3600
11 Calculate Volume of Runoff Reduction Vrr
Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in
Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) V'r 2,851 ft
12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs
13 Volume Summary
Surface Storage:Basin Unimproved areas 0.10-0.30
Basin Forebay V 456 ft' Streets
Asphalt 0.95
Primary Treatment/Storage Basin V 4,106 ft' Concrete 0.95
Subsurface Storage Brick 0.95
Volume Without Sediment Factor(See BMP 20 Tab) V 4,562 ft, Roofs 0.95
Gravel 0.75
Fields:Sandy soil Soil Type
Slope A B C C
Flat:0-2% 0.04 0.07 0.11 0
Average:2-6% 0.09 0.12 0.15 0
Steep:>6% 0.13 0.18 0.23 0
Adapted from ASCE
\\ES-1\Projects\2025\251114\Correspondence\Calcs\Storm Drain Calc-BED 1.3.xlsm 4/8/2026,1:49 PM
Version 10.5,November 2018
ACHD Calculation Sheet for Sand/Grease Traps
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the
Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must
result in facilities that meet or exceed these calculations in order to be accepted.
$ 1 ;4'1 i4n1v� �,t� .4;. a��u> +1. y,�,'fli 1�'. i a�, '�"'�> }�� ' �..,a d 5��r.. Ji��. j 7. � 1•, `;�r'+{i)� ri�sn.�.,y,..r'.. .; .. ;PtM,�, *R.. .:.:,o< ?,. : �� � :A., 1 �v'S��'T 3,rC., n��m•.f t a r k' .;1,,. i��;t;:�. ,{ a;� �.. d� r. } (9 -
f,J�a.,1Gu.��)S,.x:u>Lu
User input in yellow cells.
1 Project Name SPRINGDAY SUBDIVISION BED 1.3
2 Enter number of Sand/Grease Traps(25 max) 1
Number of Peak Flow Baffle Throat Velocity Is the
[71000G
Spacing width Area(ft2) 0.5 fps Velocity
S/G Traps Q-cfs
inch inch max. ok?
1 2.39 20 48 6.67 0.36
Reference for Throat widths(inch)
ADS
Boise Lar-ken WQU,
Vault BMP 16
1000 G 48.0 50.5 n/a
1500 G 60.0 61.5 n/a
WQU 1000 n/a n/a 60
WQU1500 n/a n/a 60
\\ES-1\Projects\2025\251114\Correspondence\Calcs\Storm Drain Calc- BED 1.3.x1sm 4/8/2026, 1:49 PM
Version 10.0, May 2018
ACHD Calculation Sheet for Sizing Vertical Sand Filters
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's
calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that
meet or exceed these calculations in order to be accepted.
Note this spreadsheet pulls information from the"Peak QV"tab
Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab)
User input in yellow cells.
Project Name SPRINGDAY SUBDIVISION BED 1.3
Enter number of Seepage Beds(25 max) 1
Design Storm Unlined Side 100 'Q,V'
Design Storm Lined Side 2Q�
Weighted Runoff Coefficient C 0.50 Link to: QV TR55
Area A(Acres) 2.64 acres
Approved discharge rate(if applicable) 0.00 cfs
100 Year Storm Volume V 4,562 ft3
2 Year Storm Volume V2 1,236 ft3
Width of Unlined Side W 22.1 23 ft
Width of Lined Side W2 6.0
Set Total Design Depth of All Drain Rock D 6.0 ft
Rock Only,Do Not Include Filter Sand Depth c D2 6.0 ft
Void Ratio of Drain Rock Voids 0.4
0.4 for 1.5"-2"drain rock and 3/4"Chips
Design Infiltration Rate(8 in/hr max) Perc 1.50 in/hr
Size of Perf Pipe(Perf 360°) Dia pipe 12 in
Design Length of Unlined Side L 86
Design Length of Lined Side L 86 86 ft
Time to Drain Unlined Side 43.2 hours
90%volume in 48-hours minimum OK
Length of WQ&Overflow Perf Pipes 86 86 ft
Perf Pipe Checks.Qperf>=Qpeak; OK
where Qperf=CdxAxV(2xgxH)
ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These
calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted.
Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab)
User input in yellow cells.
1 Project Name SPRINGDAY SUBDIVISION BED 1.4
2 Is area drainage basin map provided? YES
(map must be included with stormwater calculations)
3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100
4 Enter number of storage facilities(25 max)
Click to Show More Subbasins ❑
Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin
1 Subbasin 2 3 4 5 6 7 8 9 10
5 Area of Drainage Subbasin(SF or Acres) Acres 1.50 1.32
Acres 2.82
6 Determine the Weighted Runoff Coefficient(C) 0.50 0.50
C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted AvgJ 0.50
7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate
10 Min. Estimated Runoff Coefficients for Various Surfac
Type of Surface Runoff Coefficients"
Business
Hydraulic Downtown areas 0.70-0.95
Radius Flow Flow Urban neighborhoods 0.50-0.70
Intercept A/Wet Velocity V Time Residential
ID Pipe Size(in) Slope(f/f) Coef. Length Manning n Perm (fps) (min) Single Family 0.35-0.50
Multi-family 0.60-0.75
Segment 1:Pipe Flow Residential(rural) 0.25-0.40
a Apartment Dwelling Areas 0.70
Industrial and Commercial
Segment 2:Gutter Shallow Concentrated Flow Light areas 0.
Heavy areas 0.90
0
b 0.005 0.619 358 1.4 4.3 Parks,Cemeteries 0.10-0.25
Playgrounds 0.20-0.35
Segment 3:Overland Sheet Flow By TR-55,<300-ft Railroad yard areas 0.20-0.40
c 0.020 60 0.240 3.9 15.5
Computed Tc= 19.8
User-Entered Tc= 19.8
8 Determine the average rainfall intensity(i)from IDF Curve based on i 2.18 in r
y Calculate the Post-Development peak discharge(QPeak) Qpeak 3.07 cfs
10 Calculate total runoff vol(V)(for sizing primary storage) V 4,873 ft
V=Ci(Tc=60)Ax3600
it Calculate Volume of Runoff Reduction Vrr
Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in
Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) V« 3,046 ft
12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs
13 Volume Summary
Surface Storage:Basin Unimproved areas 0.10-0.30
Basin Forebay V 487 ft' Streets
Asphalt 0.95
Primary Treatment/Storage Basin V 4,386 ft' Concrete 0.95
Subsurface Storage Brick 0.95
Volume Without Sediment Factor(See BMP 20 Tab) V 4,873 ft' Roofs 0.95
Gravel 0.75
Fields:Sandy soil Soil Type
Slope A B C D
Flat:0-2% 0.04 0.07 0.11 0
Average:2-6% 0.09 0.12 0.15 0
Steep:>6% 0.13 0.18 0.23 0
Adapted from ASCE
\\ES-1\Projects\2025\251114\Correspondence\Calcs\Storm Drain Calc-BED 1.4.xlsm 4/8/2026,1:51 PM
Version 10.5,November 2018
ACHD Calculation Sheet for Sand/Grease Traps
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the
Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must
result in facilities that meet or exceed these calculations in order to be accepted.
-7M
User input in yellow cells.
1 Project Name SPRINGDAY SUBDIVISION BED 1.4
2 Enter number of Sand/Grease Traps(25 max) 1
Number of Peak Flow Baffle Throat Velocity Is the
Vault Size Spacing width Area(ft2) 0.5 fps Velocity
S/G Traps Q-cfs inch inch max. ok?
1000 G 1 3.07 20 48 6.67 0.46
Reference for Throat widths(inch)
Boise ADS
Vault Lar-ken WQU,
BMP 16
1000 G 48.0 50.5 n/a
1500 G 60.0 61.5 n/a
WQU1000 n/a n/a 60
WQU1500 n/a n/a 60
\\ES-1\Projects\2025\251114\Correspondence\Calcs\Storm Drain Calc- BED 1.4.x1sm 4/8/2026, 1:51 PM
Version 10.0, May 2018
ACHD Calculation Sheet for Sizing Vertical Sand Filters
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's
calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that
meet or exceed these calculations in order to be accepted.
Note this spreadsheet pulls information from the"Peak QV"tab
Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab)
User input in yellow cells.
Project Name SPRINGDAY SUBDIVISION BED 1.4
Enter number of Seepage Beds(25 max) 1
Design Storm Unlined Side 100 'Q,V'
Design Storm Lined Side 2 LQV
I QV TR55
Weighted Runoff Coefficient C 0.50 Link to:
Area A(Acres) 2.82 acres
Approved discharge rate(if applicable) 0.00 cfs
100 Year Storm Volume V 4,873 ft3
2 Year Storm Volume V2 1,320 ft3
Width of Unlined Side W 22.1 22.5 ft
Width of Lined Side W2 6.0
Set Total Design Depth of All Drain Rock D 6.0 ft
Rock Only,Do Not Include Filter Sand Depth c D2 6.0 ft
Void Ratio of Drain Rock Voids 0.4
0.4 for 1.5"-2"drain rock and 3/4"Chips
Design Infiltration Rate(8 in/hr max) Perc 1.40 in/hr
Size of Perf Pipe(Perf 3600) Dia pipe 12 in
Design Length of Unlined Side L 92
Design Length of Lined Side L 92 92 ft
Time to Drain Unlined Side 46.3 hours
90%volume in 48-hours minimum
Length of WQ&Overflow Perf Pipes 92 92 ft
Perf Pipe Checks.Qperf>=Qpeak;
where Qperf=CdxAxV(2xgxH)
ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology.These
calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted.
Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab)
User input in yellow cells.
1 Project Name SPRINGDAY SUBDIVISION BED 1.5
2 Is area drainage basin map provided? YES
(map must be included with stormwater calculations)
3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100
4 Enter number of storage facilities(25 max)
Click to Show More Subbasins ❑
Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin
1 Subbasin 2 3 4 5 Subbasin 6 7 8 9 10
5 Area of Drainage Subbasin(SF or Acres) Acres 0.45 0.31
Acres 0.76
6 Determine the Weighted Runoff Coefficient(C) 0.50 0.50
C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg1 0.50
7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 user Calculate
min 10 Min. Estimated Runoff Coefficients for Various Surface
Type of Surface Runoff Coefficients"I
Business
Downtown areas 0.70-0.95
Hydraulic Urban neighborhoods 0.50-0.70
Radius Flow Residential
Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50
ID Pipe Size(in) Slope(ft/ft) Coeff. Length Manning n Perm (fps) (min) Multi-family 0.60-0.75
Residential(rural) 0.25-0.40
Segment 1:Pipe Flow Apartment Dwelling Areas 0.70
a Industrial and Commercial
Light areas 0.90
Segment 2:Gutter Shallow Concentrated Flow Heavy areas 0.90Parks,Cemeteries 0.10-0.25
b 0.008 0.619 183 1.8 1.7 Playgrounds 0.20-0.35
Railroad yard areas 0.20-0.40
Segment 3:Overland Sheet Flow By TR-55,<300-ft
c 0.020 48 0.240 3.7 13.0
Computed Tc= 14.6
User-Entered Tc= 14.6
8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.58 in r
y Calculate the Post-Development peak discharge(QPeak) Qpeak 0.98 cfs
10 Calculate total runoff vol(V)(for sizing primary storage) V 1,313 ft
V=Ci(Tc=60)Ax3600
11 Calculate Volume of Runoff Reduction Vrr
Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in
Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 821 ft'
12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs
13 Volume Summary Unimproved areas 0.10-0.30
Surface Storage:Basin Streets
Basin Forebay V 131 ft' Asphalt 0.95Concrete 0.95
Primary Treatment/StorageBasin V 1,182 ft' Brick 0.95
Subsurface Storage Roofs 0.95
Volume Without Sediment Factor(See BMP 20 Tab) V 1,313 ft' Gravel 0.75
Fields:Sandy soil Soil Type
Slope A B C D
Flat:0-2% 0.04 0.07 0.11 0.
Average:2-6% 0.09 0.12 0.15 0.
Steep:>6% 0.13 0.18 0.23 0.
Adapted from ASCE
\\ES-1\Projects\2025\251114\Correspon den ce\Calcs\Storm Drain Calc-BED 1.5.xlsm 4/8/2026,2:11 PM
Version 10.5,November 2018
ACHD Calculation Sheet for Sand/Grease Traps
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the
Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must
result in facilities that meet or exceed these calculations in order to be accepted.
Steps for Sand/Grease Trap Velocity Calculation
User input in yellow cells.
1 Project Name SPRINGDAY SUBDIVISION BED 1.5
2 Enter number of Sand/Grease Traps(25 max) 1
Number of Peak Flow Baffle Throat Velocity Is the
[71000G
Spacing width Area(ft2) 0.5 fps Velocity
S/G Traps Q-cfs
inch inch max. ok?
1 0.98 20 48 6.67 0.15
Reference for Throat widths(inch)
ADS
Boise Lar-ken WQU,
Vault BMP 16
1000 G 48.0 50.5 n/a
1500 G 60.0 61.5 n/a
WQU1000 n/a n/a 60
WQU1500 n/a n/a 60
\\ES-1\Projects\2025\251114\Correspondence\Calcs\Storm Drain Calc- BED 1.5.x1sm 4/8/2026, 1:53 PM
Version 10.0, May 2018
ACHD Calculation Sheet for Sizing Seepage Bed With Optional Chambers
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the
Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in
facilities that meet or exceed these calculations in order to be accepted.
Note this spreadsheet pulls information from the"Peak QV"tab
Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab)
User input in yellow cells.
1 Project Name SPRINGDAY SUBDIVISION BED 1.5
2 Enter number of Seepage Beds(25 max) 1
3 Design Storm 100
4 Weighted Runoff Coefficient C 0.50 link to: LOV
QV TR55
5 Area A(Acres) 0.76 acres
6 Approved discharge rate(if applicable) 0.00 cfs
7 Is Seepage Bed in Common Lot? Yes V 1,313 ft3 0%Sediment
8 Set Total Design Width of All Drain Rock W 6.0 ft
9 Set Total Design Depth of All Drain Rock D 4.0 ft
Rock Only,Do Not Include Filter Sand Depth or Cover
10 Void Ratio of Drain Rock Voids 0.4
0.4 for 1.5"-2"drain rock and 3/4"Chips
11 Design Infiltration Rate(8 in/hr max) Perc 1.00 in/hr
12 Size of WQ Perf Pipe(Perf 1800) Dia pipe 18 in
13 Size of Overflow Perf Pipe(Perfs 3600),READ if Q100>3.3 cfs in
14 Calculate Total Storage per Foot Spf 10.3 ft3/ft
15 Calculate Design Length L 128 128 ft
Override Value Required for Chambers
16 Variable Infiltration Window L SWL 128 ft
17 Variable Infiltration Window W SWW 6.0 ft
18 Time to Drain 18.5 hours
90%volume in 48-hours minimum
19 Length of WQ&Overflow Perf Pipes 128 ft
20 Perf Pipe Checks.Qperf>=Qpeak;
where Qperf=CdxAxd(2xgxH)
Optional Storage Chambers
Note:This assumes chambers are organized in a rectangular layout.
1-StormTech,
1 Type of Chambers SC740
2 Volume to Store V 0 ft3
3 Installed Chamber Width Cw 4.25 ft
Installed Chamber Depth Cd 2.50 ft
Installed Chamber Height Ch 7.12 ft
4 Chamber Void Factor
5 Chamber Storage Volume,Without Rock,Per Manuf 45.90 ft'/Unit
6 Chamber Storage Volume,With Rock,Per Manuf 74.90 ft3/Unit
7 Total Number of Units Required 0 ea
8 Area of Infiltration Aperc ft2
9 Volume Infiltration Vperc 0 ft3/hr
10 Time to Drain hours
90%volume in 48-hours minimum
\\ES-1\Projects\2025\251114\Correspondence\Calcs\Storm Drain Calc-BED 1.5.xism 4/8/2026,1:53 PM
Version 10.0,May 2018
ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These
calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted.
Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab)
User input in yellow cells.
1 Project Name SPRINGDAY SUBDIVISION BED 1.6
2 Is area drainage basin map provided? YES
(map must be included with stormwater calculations)
3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100
4 Enter number of storage facilities(25 max)
Click to Show More Subbasins ❑
Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin
1 Subbasin 2 3 4 5 Subbasin 6 7 8 9 10
5 Area of Drainage Subbasin(SF or Acres) Acres 0.37 0.12 0.56
Acres 1.05
6 Determine the Weighted Runoff Coefficient(C) 0.50 0.50 0.50
C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg1 0.50
7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate
min 10 Min. Estimated Runoff Coefficients for Various Surfao
Type of Surface Runoff Coefficients"I
Business
Downtown areas 0.70-0.95
Hydraulic Urban neighborhoods 0.50 0.70
Radius Flow Residential
Intercept A/Wet Velocity V Flow Time Single Family 0.35-0.50
ID Pipe Size in Slope ft ft Coeff. Len (fps) min Multi-family 0.60-0.75
p ( ) p ( / ) Length Manning n Perm (p) (min) Residential(rural) 0.25-0.40
Segment 1:Pipe Flow
Apartment Dwelling Areas 0.70
a Industrial and Commercial
Light areas 0.80
Segment 2:Gutter Shallow Concentrated Flow Heavy areas 0.90
Parks,Cemeteries 0.10-0.25
b 0.670 0.619 368 16.6 0.4 Playgrounds 0-20-0.35
Railroad yard areas 0.20-0.40
Segment 3:Overland Sheet Flow By TR-55,<300-ft
c 0.020 60 0.240 3.9 15.5
Computed Tc= 15.9
User-Entered Tc= 15.9
8 Determine the average rainfall intensity(i)from IDF Curve based on Tc I 2.18 in r
V Calculate the Post-Development peak discharge(QPeak) `peak 1.14 cfs
10 Calculate total runoff vol(V)(for sizing primary storage) V 1,814 ft
V=Ci(Tc=60)Ax3600
11 Calculate Volume of Runoff Reduction Vrr
Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in
Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vr, 1,134 ft'
12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs
13 Volume Summary Unimproved areas 0.10-0.30
Surface Storage:Basin Streets
-------------
Basin Forebay V 181 ft Asphalt 0.95
Concrete 0.95
Primary Treatment/Storage Basin V 1,633 ft' Brick 0.95
Subsurface Storage Roofs 0.95
Volume Without Sediment Factor(See BMP 20 Tab) V 1,814 ft' Gravel 0.75
Fields:Sandy soil Soil Type
Slope A B C D
Flat:O-2% 0.04 0.07 0.11 0.
Average:2-6% 0.09 0.12 0.15 0.
Steep:>6% 0.13 0.18 0.23 0.
Adapted from ASCE
\\ES-1\Projects\2025\251114\Correspondence\Calcs\Storm Drain Calc-BED 1.6.xlsm 4/8/2026,2:12 PM
Version 10.5,November 2018
ACHD Calculation Sheet for Sand/Grease Traps
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the
Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must
result in facilities that meet or exceed these calculations in order to be accepted.
User input in yellow cells.
1 Project Name SPRINGDAY SUBDIVISION BED 1.6
2 Enter number of Sand/Grease Traps(25 max) 1
Number of Peak Flow Baffle Throat Velocity Is the
[71000G
Spacing width Area(ft2) 0.5 fps Velocity
S/G Traps Q-cfs inch inch max. ok?
1 1.14 20 48 6.67 0.17
Reference for Throat widths(inch)
Boise ADS
Vault Lar-ken WQU,
BMP 16
1000 G 48.0 50.5 n/a
1500 G 60.0 61.5 n/a
WQU 1000 n/a n/a 60
WQU1500 n/a n/a 60
\\ES-1\Projects\2025\251114\Correspondence\Calcs\Storm Drain Calc-BED 1.6.xlsm 4/8/2026, 1:55 PM
Version 10.0, May 2018
ACHD Calculation Sheet for Sizing Seepage Bed With Optional Chambers
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the
Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in
facilities that meet or exceed these calculations in order to be accepted.
Note this spreadsheet pulls information from the"Peak QV"tab
Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab)
User input in yellow cells.
1 Project Name SPRINGDAY SUBDIVISION BED 1.6
2 Enter number of Seepage Beds(2S max) 1
3 Design Storm 100
4 Weighted Runoff Coefficient C 0.50 Link to: Qv
5 Area A(Acres) 1.05 acres QV TR55
6 Approved discharge rate(if applicable) 0.00 cfs
7 Is Seepage Bed in Common Lot? Yes V 1,814 ft3 0%Sediment
8 Set Total Design Width of All Drain Rock W 15.0 ft
9 Set Total Design Depth of All Drain Rock D 3.2 ft
Rock Only,Do Not Include Filter Sand Depth or Cover
10 Void Ratio of Drain Rock Voids 0.4
0.4 for 1.5"-2"drain rock and 3/4"Chips
11 Design Infiltration Rate(8 in/hr max) Perc 1.50 in/hr
12 Size of WQ Perf Pipe(Perf 180°) Dia pipe 18 in
13 Size of Overflow Perf Pipe(Perfs 3600),READ if Q100>3.3 cfs in
14 Calculate Total Storage per Foot Spf 21.3 ft3/ft
15 Calculate Design Length L 85 85 ft
Override Value Required for Chambers
16 Variable Infiltration Window L SWL 85 85.0 ft
17 Variable Infiltration Window W SWW 15.0 ft
18 Time to Drain 10.2 hours
90%volume in 48-hours minimum
19 Length of WQ&Overflow Perf Pipes 85 ft
20 Perf Pipe Checks.Qperf>=Qpeak;
where Qperf=CdxAxV(2xgxH)
- - .
Optional Storage Chambers
Note:This assumes chambers are organized in a rectangular layout.
1-StormTech,
1 Type of Chambers SC740
2 Volume to Store V 0 ft3
3 Installed Chamber Width Cw 4.25 ft
Installed Chamber Depth Cd 2.S0 ft
Installed Chamber Height Ch 7.12 ft
4 Chamber Void Factor
5 Chamber Storage Volume,Without Rock,Per Manuf 45.90 ft'/Unit
6 Chamber Storage Volume,With Rock,Per Manuf 74.90 ft3/Unit
7 Total Number of Units Required 0 ea
8 Area of Infiltration Aperc ft 2
9 Volume Infiltration Vperc 0 ft3/hr
10 Time to Drain hours
90%volume in 48-hours minimum
\\ES-1\Projects\2025\251114\Correspondence\Calcs\Storm Drain Calc-BED 1.6.xlsm 4/8/2026,1:55 PM
Version 10.0,May 2018
ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology.These
calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted.
Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab)
User input in yellow cells.
1 Project Name SPRINGDAY SUBDIVISION BED 1.7
2 Is area drainage basin map provided? YES
(map must be included with stormwoter calculations)
3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100
4 Enter number of storage facilities(25 max)
Click to Show More Subbasins ❑
Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin
1 Subbasin 2 3 4 5 Subbasin 6 7 8 9 10
5 Area of Drainage Subbasin(SF or Acres) Acres 0.50 0.45
Acres 0.95
6 Determine the Weighted Runoff Coefficient(C) 0.50 0.50
C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg1 0.50
7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate
min 10 Min. Estimated Runoff Coefficients for Various Surface
Type of Surface Runoff Coefficients"I
Business
Downtown areas 0.70-0.95
Hydraulic Urban neighborhoods 0.50-0.70
Radius FlowLFlowTime
Residential
Intercept A/Wet Velocity V Single Family 0.35-0.50
75
ID Pi a Size in Slo e ft ft Coeff. Len th Mannin n Perm f s Multifamily 0.25-0.40p ( ) p ( / ) g g (p) Residential(rural) 0.25-0.40
Segment 1:Pipe Flow Apartment Dwelling Areas 0.70
a Industrial and Commercial
Light areas 0.80
Segment 2:Gutter Shallow Concentrated Flow Heavy areas 0.90
Parks,Cemeteries 0.10-0.25
b 0.430 0.619 278 13.3 1 Playgrounds 0.20-0.35
Railroad yard areas 0.20-0.40
Segment 3:Overland Sheet Flow By TR-55,<300-ft
c 0.020 65 0.240 3.9 16.5
Computed Tc- 16.9
User-Entered Tc= 16.9
8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.18 in hr
y Calculate the Post-Development peak discharge(QPeak) Qpeak 1.04 cfs
10 Calculate total runoff vol(V)(for sizing primary storage) V 1,642 ft
V=Ci(Tc=60)Ax3600
it Calculate Volume of Runoff Reduction Vrr
Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in
Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vr, 1,026 ft'
12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs
13 Volume Summary Unimproved areas 0.10-0.30
Surface Storage:Basin Streets
Basin Forebay V 164 ft' Asphalt 0.95
Concrete 0.95
Primary Treatment/Storage Basin V 1,477 ft' Brick 0.95
Subsurface Storage Roofs 0.95
Volume Without Sediment Factor(See BMP 20 Tab) V 1,642 ft' Gravel Fields:Sandy soil Soil Soil Type
Slope A BLO.23
D
Flat:O-2% 0.04 0.070.
Average:2-6% 0.09 0.120.
Steep:>6% 0.13 0.180.
Adapted from ASCE
\\ES-1\Projects\2025\251114\Correspondence\Calcs\Storm Drain Calc-BED 1.7.xlsm 4/8/2026,1:56 PM
Version 10.5,November 2018
ACHD Calculation Sheet for Sand/Grease Traps
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the
Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must
result in facilities that meet or exceed these calculations in order to be accepted.
User input in yellow cells.
1 Project Name SPRINGDAY SUBDIVISION BED 1.7
2 Enter number of Sand/Grease Traps(25 max) 1
Number of Peak Flow Baffle Throat Velocity Is the
S/G Traps Q-cfs
Vault Size Spacing width Area(ft2) 0.5 fps Velocity
inch inch max. ok?
1000 G 1 1.04 20 48 6.67 0.16
Reference for Throat widths(inch)
ADS
Boise Lar-ken WQU,
Vault BMP 16
1000 G 48.0 50.5 n/a
1500 G 60.0 61.5 n/a
WQU1000 n/a n/a 60
WQU1500 n/a n/a 60
\\ES-1\Projects\2025\251114\Correspondence\Calcs\Storm Drain Calc-BED 1.7.xlsm 4/8/2026, 1:56 PM
Version 10.0, May 2018
ACHD Calculation Sheet for Sizing Seepage Bed With Optional Chambers
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the
Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in
facilities that meet or exceed these calculations in order to be accepted.
Note this spreadsheet pulls information from the"Peak QV"tab
Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab)
User input in yellow cells.
1 Project Name SPRINGDAY SUBDIVISION BED 1.7
2 Enter number of Seepage Beds(25 max) 1
3 Design Storm 100
4 Weighted Runoff Coefficient C 0.50 link to: LOV
QV TR55
5 Area A(Acres) 0.95 acres
6 Approved discharge rate(if applicable) 0.00 cfs
7 Is Seepage Bed in Common Lot? Yes V 1,642 ft3 0%Sediment
8 Set Total Design Width of All Drain Rock W 15.0 ft
9 Set Total Design Depth of All Drain Rock D 3.0 ft
Rock Only,Do Not Include Filter Sand Depth or Cover
10 Void Ratio of Drain Rock Voids 0.4
0.4 for 1.5"-2"drain rock and 3/4"Chips
11 Design Infiltration Rate(8 in/hr max) Perc 1.00 in/hr
12 Size of WQ Perf Pipe(Pert 180°) Dia pipe 18 in
13 Size of Overflow Perf Pipe(Perfs 3600),READ if Q100>3.3 cfs in
14 Calculate Total Storage per Foot Spf 19.4 ft3/ft
15 Calculate Design Length L 85 ft
Override Value Required for Chambers
16 Variable Infiltration Window L SWL 85 ft
17 Variable Infiltration Window W SWW 15.0 ft
18 Time to Drain 14.0 hours
90%volume in 48-hours minimum
19 Length of WQ&Overflow Perf Pipes 85 ft
20 Perf Pipe Checks.Qperf>=Qpeak;
where Qperf=CdxAxV(2xgxH)
Optional Storage Chambers
Note:This assumes chambers are organized in a rectangular layout.
1-StormTech,
1 Type of Chambers SC740
2 Volume to Store V 0 ft3
3 Installed Chamber Width Cw 4.25 ft
Installed Chamber Depth Cd 2.50 ft
Installed Chamber Height Ch 7.12 ft
4 Chamber Void Factor
5 Chamber Storage Volume,Without Rock,Per Manuf 45.90 ft3/Unit
6 Chamber Storage Volume,With Rock,Per Manuf 74.90 ft3/Unit
7 Total Number of Units Required 0 ea
8 Area of Infiltration Aperc ft2
9 Volume Infiltration Vperc 0 ft3/hr
10 Time to Drain hours
90%volume in 48-hours minimum
\\ES-1\Projects\2025\251114\Correspondence\Calcs\Storm Drain Calc-BED 1.7.xlsm 4/8/2026,1:56 PM
Version 10.0,May 2018
YY
•- .. ...- s4ss ...S:• ..
: •• t9T #d E
9
G ..
•..e .•ease•.e.ee.e• ...-... ...-.-. { ....... ....-... SS4Y•Y:':::
'44 ee • •ei..s.Lii4\• ..e •eeaeo .. ��... ,� ��p� , .. ...........................................
Y8 4T%ppC�p�pp 'f�'•iL LW ...ees e.•• ._ :te:: •CY: ••Pt•e e.es.•eeee..e..e .... '[f.
: lA
°r'n� ° .... 'E'
.. `�
Or .�� •........ ...e. �,•4W•'
�- ........•:L::•..._.�..-..mac _ �� .......•..• ::•• -•••:
...-..-. ••Se•L-e.3yy.•.pdR'6g•>4GP<e uur. es•e
..-.._.. .. .....-.-...........-..._......_. _ r
_ _.. _ _ _ ..._ .r. _-__ _.-._. _ - .................. eg a ....... ................
................. ..........
II I I GND=2538.s T . `.�.';- _
4 #2 '
P
GND WTR=2532.7± I I GND=2539.1± T.P.#3 _
I"11 II I I .-
6
..........253g............@LOG%4 I I GND =2529.1�• 4"e BLOCK 11
II 2�4 GND WTR=25W.B± \ 9 .�
I II I 24 23 21 20 �I
I =�=
II II i
I II I � 1�
II 27 fi d► ,
c, BLOCK\11
i
--11 1014 AC I GDAY SUBDIV SIO 0. I I 24 I
26 I I
.2 Vic® I� ► 14 - _ - - - _ _ _ - - = _ _ = _ _ _ - - Y - 23
BLOCK i - � - - - - = =
_ -
I
�. US TC TC - _ - _ - Subdivision No. 1 P FLOW STORM DRAINAGE VOLUME
W.BE CHR ST. C ��1.2 AC. I I Sp ingday Su n
II Il I I - _ _ _ _
u u Water a! Storm
Quality�\ � I f�`:� I Q2-0 50 12A ( C 0 50) Single Family V2 Area�468 (Assumes C 0 50) Wat ; l 0 26
Job . . 25111 �5=0.50125A (Assu C=0.50) Single Farm V25=Area 1242 (Assumes
- III II I I i _• .••'•• •..... -= - - - - - •�-- - - - - - -
25 _ _
I II III I I l� 10 �` \ 1 I 1 I 9-Feb-26 Q,00-0.501,00A (Assumes C=0.50) Single Family V,00=Area 1728 (Assumes C 0.50) I - 0.96�a
.. y
- III I( I i o I i Ii II ►I � •�s :: I 1.1 AC. ---• --.' . " .-'••• I I 22 �•.. ..... .... -' 1 =:�
11 11 F II 11 0 11 `L I I I I I BASIN AREA Tc I I I V V V
III III I 2
II II I I ��. 1 K7 •` ••'. 1 W 28 100 Q2 Q25 Q1(K! 2 2S 100
I II it I i 1130 29 28 27 20 I 24 tih 1 11 II 1 I 1.1 A.C. I I v I 1 18 I NO. acres minutes c#s cfs cfs cubic feet cubic feet cubic feet
II II II 2a � : 21 20 II 19 18 17 181I it
4 5 - III I BLOCKS I I I I
T.P.#13 � •'•.
II II I I I f 1' If 11 BLOCK I I II li I I 11 11 .::
: 1 : GND=2541.5±
a.. GND WTR=253MOt 8 12 1
I I �- I �� ` � 0.41 12.60 0.61 1.62 2.58 .13 0.33 0.53 192 509 708
BUCKS - I 1s I 2 0.47 15.10 0.53 1.41 2.18 0.13 0.33 .51 220 584 812
1 3 TC I I BLOCKb 1 i 1 I I I
a J •
4 v 1 2 3 4 b 8 7 8 9 10 11 12 13 14 _ I I BLOCK 11 I.: �. I See a Bed No. 1.1 0.88 15.10 0.53 1.41 2.18 0.23 0.62 0.96 412 1093 1521
BLOCK �- I 1 1=
5a � II
2
T.P. 2 3 0.51 12.80 0.61 1.62 2.58 0.16 0.41 0.66 239 633 881
I 8 I 14 8 I 1
GND=254o.e+ 254� r 1a. 1 I I t4 I I 4 0.91 15.00 0.53 1.41 2.18 0.24 0.64 0.99 426 1130 1572
• n. rt GRID'ii1iTR=2529.6± ..........-"-•• ..?S42 � .•ems
., U AC. I H H I I
e
". v : ®'S �. "' Seepage Bed No. 1.2 1.42 15.00 .53 1.41 2.18 0.38 1.00 1.55 665 1764 2454
5 15 11 I I I Iv
BLOCK 7 I I I 5 0.70 17.60 0.53 1.41 2.18 0..19 0.49 .76 328 869 1210
��//�� = W.BER ® I !- = 2542--....... I I
/ . W.BE O ST. 1
TC/ • TC ( 1 6 1.94 21.40 0.43 1°14 1.81 0.42 1.11 1.76 908 2409 3352
,. S 1.3 .4 4 4
8 4
e
� I I I ee a Bed W. 2.� 21 0 0. 3 1.1 1,81 0.57 1.50 2.39 1236 3279 4562
']
a- �- ll II 11'....
1 91:�=
R .. -- I III I I I
11 I I I
0.9 . 8 10 I I 1 : :1<_ 7 1.50 19.50 .53 1.41 2.18 0.40 1. 1.64 702 1863 2592
1.5 AC. I I I I Ids• I 8 1.32 19.10 0.53 1.4 2.18 0.35 0.93 1.44 618 1639 2281
% 1 I 17 �!-
3 I I II II 1 I I Seepage Bed No. 1.4 2.82 19.50 0.53 1.41 2.18 0. 15 1.99 3.07 1320 3502 4873
1 I ........'g.Zg4t 18 17 16....... 15 14 13 12 10 7 11 BLEtCK7 11 19
15
11 � I ! I
1 BL®CK3 T.P. 11 ti I:eEa
a a
CiB�9D=2542.7±
m°
0.5 A>C.
II I x 9 0.45 10.80 0.61 1.62 2.58 0.14 0.36 0.58 211 559 778
GND� =253,.2± z I II III- 1 I 10 0.31 14.60 0.61 1.62 2°58 0.09 0.25 0.40 145 385 536
w g asp 18
r
`. � 43 I I I 19 I See a Bed No. 1.5 0.76 14.60 0.61 1.62 2.58 0.23 0.62 0.98 356 944 1313
8 12 � TC f I
1 I BLOCK 11
1 I
12 .1 X
,9
T -
- -� I `• 11 0.37 11.00 0.61 1.62 2.58 0.11 0.30 0.48 173 460 639
°t
12 0.12 10.00 0.61 1.62 2.58 0. 0.1 0.15 56 149 207
9
ASPINSIGIC I 13 0.56 15.90 0.53 1.41 2.18 015 9 61 262 696 968
S RI GDAY SU DVIS14 0. '
_ 8 4 13 W.AsSToE sT.
•
TC
0.3 AC. No 1 6 15 1 0 1 14
0.5 AC. - -
1. .41 4 1 1 Q4 1814
Seepage Bed 05 .90 0.53 2.18 0.28 .74 . 9 3
.
P DAYSUBDIVISION 32 $ 4 $K3 7 _ BLOCKB - - - ®, 14 0.50 10.30 0.61 1.62 2.58 .15 0.41 0.65 234 621RINN14P.*4 , I I
r T.P. 10 0.4 - 543.5± I I e (: 0.36 0.58 211 559 778
R� GND=2544.1�
G�D_2 ---� 15 0.45 14.70 0.61 1.62 2 58 0.14
- ^' GND -2532.0�
GND 2532.ft v 13 2 _ 18 I I I f Seepage Bed No. 1.7 0°95 14.70 0.61 1.62 2. 0.29 0.77 1.23 445 1180 1642
c, F-
. 5 �
CK3 0.6 .
2 1b N
II
1
0.7 AC. T v BLoeKs I
r-
a 1 v
BLOCK1 3 17
iI
n
C, C�
r �m 4. y its W.PBP�ESTONST. _ Sprin day Subdivision No. 2 PEAK FLOW STORM DRAINAGE VOLUME
I I� I 9
r T.�. II 21 - _
T ®e
G&�fD-2543.0_ BLOCK 8
- ---r - u - (Assumes - star Quality Storm
GND 253,.0_ . .. e I I;:::� Q2-0.5012A (Ass C- 0.50) . . Single Fa V2=Area 468 (Ass C- 0.50) W i I 0.26
_ 4 18 11 I. )•I
_ _
-• �` � Job!�. . 000000 Q25-0.50125A (Assumes C- 0.50 Single FamilyV25 Area 1242 Assumes C- 0.50 I 0.69°'
.�
I I 9-Feb-26 Q,00=0.5011ooA (Assumes C= 0.50) Single Family V,00=Area 1728 (Assumes C= 0.50) 1 = 0.96"
1 I I 1.9 !�. I I I I b
• 54� �4: y :5
2
11 I
I I
� BASIN AREA I 1 V V V
•. 11 •
•: = =` ASI AR TC:.-
• 1a 2S 100 Q2 Q2B Q1O0 2 20 100
. ... .........
!I -�---- t NO. (acres) minutes cfe cfs cubic feet cubic feet cubic feet
-2544. .. - '� • ....-.... ::.::::-.:-... ._ II 1 2 3 a •�• Q 7 � I I I I I $��. 1 •I� �'
pa:�P =;r:P:e:;....: 1 iJ 8 9 I-- 10 11 1 6 14 I I 1 I°AA..a AIA. �..... I.1. K TC I AAAA?- }.4• BLOC 10
.. ,yam...
BLocK10 I + 4 1:1i\iiEo •}}.\}ae}. •449468SE::.•':..::::::::::::"
'cT.P..�5 I� •.4. I f
GND=2543.4•± ` `` `: ! I 16 1.86 20.20 0°43 1.14 1.81 0.40 1 1.68 870 2310 3214
0.5 AC. j :
T c.,
GND -25�.9_
i-
C
4d•44e d'
'a
•r fit• as•[ {e PL r d'4 �\ •a^ PI
�l•I- �
II- BLOCK 11 7 14 1. 1 7 1 3 2592
1 1.5 22.70 .4 8 •3 0• 02 86
` 0 0 3 1 0 2 86 •36 l 1
1 0CK2 TC �` 2545`•
BL •
t f v
- 13
7.
I I II .TC.::::::`::�-•�::�::�:::=:::.. .���:=:�:�:::_:::::::::::..-. I I Seepage Bed No. 2.1 3.36 22.70 0.43 1.14 1.81 0.72 1.92 3. 1572 4173 5806
sv TC • ..
�Lo�K, �. TC - - - - LI" :::::_. Y444E:: I I .- -
I I II T.P. I
b GAD=2 .7 13 9 1
.. ......-..
......
.. .,.. �.. ,fe l i
BLOC. GND =2535.2 CK9 �� II _ .. . 18 0.47 16.20 0.53 1.41 2.18 .13 0.33 0.51 220 584 812
I 1 2 3 4 i. ® 7 I I 11 I I I �545.......... I:. . I
-' ll it 11 0.5 AC.0 8 9 10 e '�s�11 1 11 8 12 I I :ra- aE::.I 19 0.47 16.20 0.53 1.41 2.18 0.13 0.33 0.51 220 812
a ... �1 • III a I 'I:
I 1 if 11 II T.P. I l I ( _ See a e Bed No. 2.2 0.94 16.20 0.53 1.41 2.18 0.25 0.66 1.02 1167 1624
�2 I I� • GND=2545.9±
I I II $ II I I 16 11 I lsl..l.l...... GNDWTR=25�.9± I I ........� 5. a _
SUBDIVISION2
• SPRINGY .
v ` �....... I I III 9 ,1 TC l I r-r- -
I1.9 ABC.
j_ _
. S rin da Subdivision No. 3 PEAK FLOW STORM DRAINAGE VOLUME
r . -
TC
a
N �� W.AU3 STQNE . a : . °. Q2=0.5012A (Assumes C°- .5 ) Single Family V2=Area 468 (Assumes C =0.50) Water Quality Storm 1 - 0.26
_ W.ALDER _•
D. TC
AC... .......... - -_ _ - _ - - - - _ - - _ - _ _ _ - -- _ Job No. : 00000 =0.50 I u C = 0.50 Single Fam; V Area* 1242 Assumes C =0.50 I = 0.69"
....... ...
UNPLATTO
-
-
-
-� (Assumes.. _ Qa5 25A 25;
-1
ri 17
9-Feb-26 Q,00=0.5011 u C= 0.50) Single Fa Vic=Area 1728 (Assumes C= 0.50) 1 =0.96"
_
ooA '( •h/
� T.P.#7 � I I ,�.°,
0.5
2g I.' I I GND=2543.2±
1.5 AC.
] i
..._........ I I GND . ± I I BASIN AREA Tc I2 126 I1 Q2 Q2b Q100 N2 V25 �1ao
-•• =2531 2
9
t I I I _ ' �,.[��• NO. acres minutes cfs cfs cf$ cubic feet) cubic feet cubic feet
10 11 12 13 14 15 18 1 17 1 18 19 20 21 22 •�7�- 24 25 28 27 I 1
.....-. ...BLOCK 2 .
I I �
17
29 1T: � 20 1.21 20°20 0.43 1.14 1.81 0.26 0.69 1.10 566 150
......... ... �, BLOCK 2',. I (: BLOCK 2
•-- 21 1.06 20.00 0.43 1.14 1.81 •23 0.60 0.96 496 1317 1832
- T.P. I I I I ' Seepage Bed No. 3.1 2.27 20.20 0.43 1.14 1.81 0.49 1.29 2.05 1062 2819 3923
GND=2538.7_
GND =2533.0+ 17 I I 17
. °
.........................:::
`•`' 23 1.20 19.60 0.53 1.41 2.18 0.32 0.85 1.31 562 1490 2074
................. ...,.........................._....._.
....................................- .-.......• ............--.....................-........... ...-.....
--- ........ See a e Bed No. 3.2 2.33 19.60 0.53 1.41 2.18 0.62 1.64 2.54 1090 2894 4026
- �'d.11STtCKROAD_ W.USTtGKR -•---........ '
- W.l9STtGK W.LMK ROAD
/-- Springday Subdivision No. 4 PEAK FLOW STORM DRAINAGE VOLUME
- Q2=0.5012A (Assumes C= 0.50) Single Family V2=Area*468 (Assumes C = 0.50) Water Quality Storm 1 =0.26"
di n _ Job No. : 00000 025=0.50125A (Assn C= .50) Single Family V25=Area 1242 (Assumes C =0.50) 1 -0,69
I I I-
DRAI GE IN NUMBER i I 9-Feb-26 Q,00=0.5011 (Assumes C= .50) Single Family V1oo=Area 1728 (Assures C= 0.50) 1 =0.96"
3 1.4 AC. W ACRE AND BASIN I ( I I
BOUNDARY E I I f I I I JA Ate SUBDa 90N BASIN AREA TC 6 126 I100 Q2 Q25 0100 V2 'V25 V100
NO. acres minutes cfs cfs cfs cubic feet cubic feet cubic feet
T.P.GND=2W.l:t TEST HOLE NUMBER AND I i z I I
GND =2536•9± GROUND ELEVATION AT T.H. / 24 1.40 20.10 0.43 1.14 1.81 0.30 .8 1.27 655 1739 2419
i
C TC
I 25 1.06 20.10 0.43 1.14 1.81 0.23 0.60 0.96 496 1317 1832
• -- -�- ME OF CONC Ti0 I / See a e Bed No. 4.1 2.46 20.10 0.43 1.14 1.81 .53 1.4 2.23 1151 3055 4251
VALLEY GUTTER I / I 26 0.22 12.80 0.61 1.62 2.58 0.07 0.18 0.28 13 273 380
27 0.39 15.00 0.53 1.41 2.18 0.10 0.27 0.43 183 484 674
STORM DRAINAGE COLLECTION SYSTEM! I Seepage Bed No. 4.2 0.61 15.00 0.53 1.41 2.18 0.16 0.43 0.66 285 758 1054
f - - -=J -1-
STORMDRAIN BED
- -- SURFACE FLOW DIRECTION REVISIONS ENGINEER SPRINGDAY SCALE 1"=80'
SUBDIVISION BOUND ENGINEERING SOLUTIONS, LLP �,gs`GENS '�dV�,� DWG.DATE 04/10/26
Joshua H. Mann, P.E, ®�C �.® �® 'yr�
. ....•... -... 2540' ••.----•... . 5 CONTOUR LINE 80 40 0 80 160 2 1029 N. ROSARIO ST., a �
Ak, D RAINAGE P]11['111)" PROJ. N0. 251 1 14�
Ste.
MERIDIAN, IDAHO 83642 20305 S OF SE j, SECTION 33, T.4N., R.1W•, B.M. SHE 1 OF 1
. ... . .. ... . .25.39' . ......... . 1' CONTOUR LINE Phone (208) 938--0980 J, h�� LLP MERIDIAN, ADA COUNTY, IDAHO
SCALE IN FE9 E-Mail: joshm0engsol.org v ���• ��P� 1029 N. ROSARIO STIR., SUITE 10
Os E OfDRN
THIS DRAWING OR FILE CONTAINS INFORMATION OWNED BY ENGINEERING SOLUTIONS,LLP AND WILL y P� MERIDIAN, IDAHO 83642DFVx'%1N1-%r%.-AE
PI
BE GOVERNED ONLY BY ENGINEERING SOLUTIONS. THESE CONTENTS MAY NOT BE REPRODUCED OR U� H' Phone (208) 938-0980 Fax (208) 938-0941
MAY ONLY BE USED WITH THE PRIOR WRITTEN CONSENT OF ENGINEERING SOLUTIONS,LLP 251114-DRN.DWG