HomeMy WebLinkAbout2001-07-11 Drainage Report DRAINAGE REPORT
ATLANTIC REALTY TRUST
342 NORTH MAIN STREET
MASSACHUSETTS
JULY , 2001
DAL
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MERRIMACK ENGINEERING SERVICES, Inc.
IQ66 Park Street
Andover, Massachusetts 01810
planners 40 engineers 40 surveyors
I
DRAINAGE REPORT
NARRATIVE
SITE DRAINAGE CALCULATIONS
PROPOSED RECHARGE FACILITY
E AND POST DEVELOPMENT
DRAINAGE SS
SUMMARY OF PEAK FLOW RATES
CALCULATIONSFLOODPLAIN FILLING AND
COMPENSATION
NARRATIVE
This project site has been designed to accommodate a multi-bay car wash facility which will
be serviced with existing Town water and sewerage systems. Access to the site will be from
a proposed 25' wide paved driveway from Route 114. On-site parking for up to eight (8)
cars will be provided in the rear of the site.
The site has also been designed with a dual purpose subsurface drainage storage system to
accommodate a detention period of stormwater runoff in order to mitigate a potential
increase in the peak rate of runoff. The size of the drainage storage system is large in order
to provide required compensatory volume to offset the filling proposed within the 100
floodplain (up to El = 236.1).
Also, a subsurface drainage system is proposed to handle all of the roof drainage and to
provide ample recharge to groundwater of this uncontaminated runoff water. The volume of
recharge is based on the `dead storage' capacity within this system. An elevated outlet pipe,
approximately 2 feet above the bottom of the precast concrete structures, will limit the
retainable capacity of the volume to be ultimately recharged, after the storm for
approximately two or three days henceforth.
To ensure that the stormwater runoff from the proposed paved parking areas will not be
creating a potential downstream pollution problem, a series of pollution mitigating treatment
measures will be implemented with the design of the site drainage system. Each catch basin
frame and grate will have a"Fossil Filter" installed to retain petroleum based contaminants
(hydro-carbons) within its "Filter Medium". Each catch basin will have a 4' deep sump for
silt and sand accumulation. The outlet pipe from each basin will have an oil trap or hood to
prevent flotables (grease, oil, and debris) from discharging from the catch basin to the
downstream waters. With these elements of prevention and pollution mitigation in-place and
periodically maintained, the flow of runoff from each catch basin to the subsurface detention
facility will be a significantly cleaner and highly treated runoff discharge. The time of
detention in these subsurface structures will also allow for further treatment of any minimal
pollutants, which get beyond the catch basin treatment measures. Additionally, a
"Stormceptor" oil separator unit will be installed at the outlet of the drainage system, prior to
stormwater discharge into the Restoration and Wetland Replication Areas. A 30" RCP
culvert will be installed at the entrance, adjacent to the existing 30" culvert, to improve
hydraulic capacity for drainage flow beneath the proposed driveway from Route 114.
An "Operation and Maintenance" Plan is proposed to be implemented from the start of
construction, throughout the duration of the construction activity (approximately six months),
and periodically on an inspectional or"as necessary" basis after the work is completed and
the development is opened for business.
PROJECT: PROPOSED ROUTE 114 CAR WASH FACILITY
APPLICANT: ATLANTIC REALTY TRUST
DATE: JULY 6, 2001
SITE DRAINAGE CALCULATIONS USING RATIONAL METHOD
Determine peak flow rates to each catch basins; use 10 year storm, time of concentration
of 5 minutes, rainfall intensity of 5.3 inches/hour
RATIONAL METHOD:
Q =CiA
Q=Peak Flow Rate (in cubic feet per second)
C =Runoff Coefficient
Impervious: 0.9
Lawn/Landscaped: 0.3
Wooded/Vegetated: 0.1
i=Rainfall Intensity(in/hr)
A=Drainage Area(acres)
PIPE FLOW CHARACTERISTICS:
n= 0.015, for RCP
0.013, for C.I.
0.011, for PVC
V=Velocity, in feet per second
d=depth of flow in pipe, in feet
REFER TO "PIPE FLOW CHART", THE "DRAINAGE PLAN", AND SHEETS 4
AND 5 OF THE PLANS FOR ANALYSIS AND DESIGN INFORMATION
1 of 3
A RIE A "A"
(CB #1 to DMH #1) -
C = 0.9 (100% impervious)
A= 1080 S.F. = 0.025 Acres
Q = 0.9x5.3 x0.025 = 0.12CFS
use 12" RCP @ S =0.015 1/1, V= 2.2 FPS, d=0.12 Ft.
AREA "B" (CB #2 to DMH #1)
C = 0.9 (100% impervious)
A= 3420 SF = 0.079 Acres
Q2 = 0.9x 5.3 x0.079 = 0.38 CFS
use 12" RCP @ S = 0.004 1/1, V= 2.0 FPS, d =0.30 Ft.
For: DMH#1 to DMH#2 and DMH#2 to DMH 93
Q = Sum of Flow from CB's #1 and #2
= 0.12 + 0.38 = 0.50 CFS
use 12" RCP @ S = 0.004 Vi, V=2.1 FPS, d = 0.35 Ft.
For: DMH#3 to Detention Facility "C"
Q = sum of flow from CB's 1, 2 and 5
0.12 + 0.38 + 0.53 = 1.03 CFS
use 12" RCP @ S = 0.004 1/1, V=2.5 FPS, d= 0.50 Ft.
AR-EA "C" (CB #3 to Detention Facility "B")
C = 0.9 (100% Impervious)
A= 3840 SF = 0.088 Acres
Q3 = 0.9 x 5.3 x 0.088 = 0.42 CFS
(Note: No over flow from `Recharge' Facility Expected)
use 12" RCP @ S = 0.008 1/1, V= 2.7 FPS, d =0.27 Ft.
2 of 3
AREA "D" (CB #4 to Detention Facility `B")
C = 0.9 (100% Impervious)
A= 12,800 SF = 0.294 Acres
Q4 = 0.9x5.3 x0.294 = 1.40CFS
use 12" RCP @ S = 0.03 1/1, V= 5.8 fps, d = .35 Ft.
1 AREA "E" (CB #5 TO DMH#3)
f
C = 0.9 (100% impervious)
A= 4935 SF = 0.11 Ac
Q = 0.9x5.3 x0.11 = 0.53 CFS
use 12" RCP @ S = 0.006 1/1, V= 2.4 FPS, d = 0.32 Ft.
AREA "F" (Building Roof Drainage to "Recharge" Facility)
C = 0.9 (100% impervious)
A= 5400 SF = 0.124 Ac
Q = 0.9x5.3 x 0.124 =0.59 CFS
use 6" cast iron rain leader @ S = 0.004
where V= 5.3 FPS, full, flow is full at 1.1 CFS
where -q = 0.59 = 0.54; v_= 0.80, v= 0.88 FPS;
Qf 1.1 V
d= 0.61, d= .61 x .5
D = 0Y
Refer to the "Hydraulic Elements for Circular Pipe" Chart and the Hydraulics of
Sewers" Chart
3 of 3
k l E i'-{
10-22 2=2=22= Drainage and Erosion Control
Use L w 5.3 inchcs per hour for I® yr sform
10.0 and 1"C = 5 minUte5
9.0
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5 6 7 8 9 10 15 20 30 40 50 60 2 3 4 5 6 8 10 12 18 24
(MINUTES) DURATION (HOURS)
Figure 1 - . Intensity - Duration - Frequency
Curve for Boston, MA -'
JOB -
MERRIMACK ENGINEERING SERVICES SHEET NO - OF _
Profess! rs • Land Surveyors • Flamers c OATE 4
GALCULATEO BY'
, U1 H10
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SCALE
RECOMMENDED RUNOFF COEFFICIENTS (C)
FOR NAL METHOD
1111Y OVERALL Cj4ARACiER OF )
rDESCRIPTION OF AREA RUNOFF COEFFICIENTS
RESIDEN'nAL
TOWN 0.70 to 7.M
BORHOOD 0.50 to 0.70
AL
E FAM4Y0.30 to 0.50
-FAMILY. DETACHED 0.40 to 0.60
-FAMILY, ATTACHED 0.80 to 0.75(SUBURBAN) OM to 0.40
APARTMENT 0.50 to 0.70
INDUSTRIAL
LIGHT 0.50 to 0.80
HEAVY 0.60 to 0.90
PARKS. CEMETERIES 0.10 to 0.25
PLAYGROUNDS Om to 0•25
RAILROAD YARD ODD to 0.25
UNIMPROVED 0.10 to 0.3
WOODLAND 0.15 to 0.3
CULTIVATED 0.40 to 0.60
SWAMP. MARSH 0.10
TABLE 10-2.02F
RECOMMENDED RUNOFF= COE=F=iCIENTS _(C)_
FOR RATIONAL NIE T HOD
(FOR SURFACE TYPE)
CHARACTER OF SURFACE I RUNOFF COEFFICIENTS
oAVEMF_NT
ASP4ALTIC AND CONCRETE 0.70 to 0.95
9RiCr 0.70 to 0.25
aCCFS 0.75 to 0.95
LAWNS, SANDY SOIL
FLAT, 2 PERCENT 0.05 to 0.10
AVERAGE. 2 TO 7 PERCENT 0.10 to 0.15
S.EBP 7 PERCENT 0.15 to OM
LAWNS. HEAVY SCIL
® FLAT. 2 PERCENT 0.13 to 0.17
AVERAGE. 2 TO 7 ®E_RCENT 0.11 to 0.
SEEP. 7 PERCENT 0Z Fo 0.
ERRIMACK ENGINEERING SERVICES JOB
Professional Englneters o Land Surveyors o Planners SHEET NO. OF —dR 66 Park Street CALCULATED BY DATE ®99
ANDOVERJ�MASSACHUSETTS 01810 FU 7
`F78) 475_3555 CHECKED BY DATE
SCALE
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MERRIMACK ENGINLERING SMWE5, W. JOS
Efti ors • Rmrws SHEET Mo of
66 Paris Sheet
VE , MASSACHUSETTS 0110 CALCULATED 6r .t DATE
(s7®) 475-3555
CHECKED SY DATE_
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FIGURE for fmmuh fr p4c ilow.
PROPOSED "RECHARGE" FACILITY
Determine the Recharge Volume Required, per Standard #3 of the Stormwater Management
Policy.
Total Recharge Volume; based on total proposed impervious pavement area, contributing to
the Site Drainage System.
To CB #1 1,080 sq. ft.
CB #2 3,420
CB #3 3,840
CB 94 12,800
CB #5 4,950
Offsite: Portion of proposed driveway contributing to
41' x 35' 1,435 to existing catch basin on Route 114 which
will not be treated
Total Impervious Area= 27,525 sq. ft. of pavement, which is the net increase in impervious
area.
Minimum Recharge Volume= 27,525 sq. ft. x 0.10" =229.4 cu. ft.
12
Which represents the minimum volume of surface runoff required, by regulations, to be
recharged on the site, based on Hydrologic Soil Group "C", as indicated on the U.S.D.A. Soil
Maps for this site.
PERMEABILITY
Permeability, or rate of infiltration, is based on an actual percolation test rate of 5 minutes per
inch, and using 0.3 inches per hour, to be conservative:
Soil Contact Surface Area of Recharge Facility
bottom: 30' x 12' = 360 s.f
sidewall: say 1' high x 2x(30' +12') = 84 s.f.
444 s.f.
Compute rate of Infiltration, I:
I = 0.3 in/hr x 1 ft./12 in x 444 s.f. x 1 hr./60 min = 0.18 c.f./min
= 1.35 gal/min
Over a period of up to 3 days, the volume capacity of recharge, V, to be expected is
calculated:
V„ = 1.35 gal/min x 60 min/hr x 24 hr/day x 3 days
V„ = 5,824 gallons (778 c.f.)
This number, being the maximum feasible recharging capacity determinant value, for
comparison with the calculated recharge volume to be discharged into the recharge facility
from the building roof top area, is greater that the Minimum Required Recharge Volume of
229.4 c.f. Therefore, the recharge time will be about 1 day. To recharge the "full" volume
(648 c.f., as calculated below) it will take approximately 2.5 days.
The proposed Recharge Facility will consist of just 6 precast concrete"Jumbo" dry wells,
butted together, and will be set at least two feet above the Seasonal High Water Table. These
structures will be H-20 rated, with a 6" thick reinforced concrete top slab.
The capacity of the "Recharge" Facility to be provided is based on storage volume,
infiltration rate and volume, and overflow provisions when evaluating and designing a
Recharge Facility proposed under pavement.
This facility will be capable of storing roof drainage up to a depth of 2' inside the structures,
before any water would be discharged through the outlet pipe proposed. This total volume
would be ultimately recharged over a longer period of time. The Storage Capacity when
"full" is approximated, by calculation, to be:
30' x 12' x0.9x2' = 648 c.f.
In order to achieve this volume of runoff from the roof area, it will require a rainfall of
approximately 0.7 inches, based on the facility being empty or"dry" prior to the storm, not
including the volume absorbed during the storm as infiltration or recharge.
At times, there will be overflow from the recharge facility into the subsurface detention
facility during the higher intensity storm events. From the analysis of the 100 year storm (6.5
inches in 24 hours), it was necessary to provide two (2) 6" C.L.D.I. overflow drain pipes
from the Recharge facility, in order to prevent an overload surcharge within the structure.
Therefore, there should be no occurrence when the capacity of the recharge facility could be
exceeded, given these conditions as designed. Refer to Subcatchment #14 (Roof Drainage)
and Pond #2 (Recharge Facility) in the Post-Development Drainage Analysis for detailed
data from the four(4) storm events.
10'-0"
'
I i
24" DIA INSPECTION COVER
I 1
I F'
_ I
1 L"
..i I
6'-0"
I
i L"
I f_
I F�
1
I L"
1 I
I 1
.-77'1 7-r-T-r-T-r-T-r-----T---T-P-T-,..,-T-'.-T-r-T-�.-T-♦•-T-r-T-TJ•
J 1 l 1 I \ J / \ / 1 ! \ I , J
PLAN VIEW
1" TAPER
4" TOP 6" H-20
�; (4) 6" DIA INLET
(3'-0" H-20) `Q, I- IOt 1 Q, ,QI
, 2'-0"
3 � DRAINAGE HOLES 4" TO 2 1/2" DIA TAPER
SECTION VIEW
ITEM NO. DW-JDW STANDARD
DW-JDWH H-20
NOTES: < •.
1. CONCRETE: 4,000 PSI MINIMUM AFTER 28 DAYS.
2. ALSO AVAILABLE IN H-20 LOADING. CONCRETE PRODUCTS, INC.
DRY WELL
JUMBO
P.O. BOX 520 - 773 SALEM ST., ROUTE 62 NO. WILMINGTON, MA 01887 PAGE C3
TEL. (508) 658-2645 FAX. (508) 658-0541
SOIL DATA
TEST PIT #1 TEST PIT2
-2 ROOT MAT 236.0 -4 ROOT MAT 236.4
_ _ _ 253.8
0 F.S.L. 0 MIXED FILL OF 236.1
2 MIXED FILL 235.7 BROKEN LEDGE 10%
„ AND 3 DIAM. CONC.
50% BROKEN LEDGE 5 YR 5/3 20 F.S.L. G1 2.5 N 234.4
j TO 2' DIAMETER MOTTLES
48 231.8 36" 5Y 4 4,5Y 4 1 233.1
EVIDENCE OF A&B 231.3 S0 L.S. 5Y 4 1 VERY FINE SAND 231.9
54" / ( 5Y 6/1, W POCKETS
F/M SAND 0 Y65 8 10� �V.F/SAND ND &
/ ( ) 2.5Y 5 6 MOTTLES
84' WATER AT 18" 228.8 78 WATER AT 18" 229.6
(PERCHED) EL.= 234.9
EL.= 234.5
TEST PIT #3 TEST PIT #4
0„ 234.8 0ll MIXED 234.4
MIXED FILL , FILL 232.3
VARIES TO Ap 25 F.S.L.
36 ' 46"(5Y 5/1 AT 36") 231.8 B 48 1 S L? 1 230.4
F/M SAND WITH 10Y 4 4
POCKETS OF F.S.L. 58 V.F. SAND 5Y 5/1 229 6
(ALL M&F) AND C WITH POCKETS OF
RAVELLY SAND M-SAND & F.S.L.
5 5/2 2.5Y 5/6 MOTTLES
' 226.3 102' 225.9
102 WATER AT- 46" (EL=231.0) WATER AT 37" (EL=231.3)
S.H.W.T. AT 56" (EL=231.8) S.H.W.T. AT 26" (EL=232.2)
TEST PIT #5 TEST PIT #6
0" 235.3 0" 235.7
22" FILL 233.5 Ap F.S.L.
A F.S.L. 10Y 2/1 5" 235.3
IB 35" F.S.L. 10Y 5/1 232.4 Bw F.S.L.
42' 231.8
2.5Y 5/6 MOTTLES 12" Cl L.S. 234.7
L.S., 5% GRAVEL 5% COARSE
C 5% COBBLES 36„ FRAGMENTS 232.7
50% - 10Y 5/8 C2 F.S.L.
50% - 5Y 5/1 MASS. & FIRM
108" 226.3 48" 1 MOTTLED 231.7
WATER AT 58" (EL=230.5) NO WATER (EL=---)
S.H.W.T. AT 35" (EL=232.4) S.H.W.T. AT 36" (EL=232.7)
PERC TEST (P-5) LEGEND
F/M FINE TO MEDIUM
0" 235.2 F.S.L. FINE SANDY LOAM
L.S. LOAMY SAND
PERC RATE=M L.V.F. LOAMY VERY FINE
USE 5 MIN./IN.
14 MIN. IN DROP M&F MASSIVE AND FIRM
PERC RATE S.H.W.T. SEASONAL HIGH WATER TABLE
40" 231.8
56" 230.5
WATER AT 52" (EL=230.9)
DEEP TEST HOLE EVALUATIONS CONDUCTED 4/5/99 & 4/12/99 BY LES GODIN, SOIL EVALUATOF
PERC. TESTS CONDUCTED 4-12-99 BY LES GODIN.
I
Data for RTE 114 CAR WASH - NORTH ANDOVER (PRE-D)
TYPE III 24-HOUR RAINFALL= 6.50 IN
Prepared by Merrimack Engineering Services 27 Mar 01
HydroCAD 5 .11 000899 (c) 1986-1999 Applied Microcomputer Systems
WATERSHED ROUTING
1 2
Fil
OSUBCATCHMENT REACH A POND I i LINK
SUBCATCHMENT 1 = RUNOFF TO DESIGN POINT #1 -> REACH 1
SUBCATCHMENT 2 = RUNOFF TO DESIGN POINT #2 -> REACH 1
REACH 1 = SUMMARY OF COMBINED FLOWS - SUBCATS #1 & 2 ->
Data for RTE 114 CAR WASH - NORTH ANDOVER (PRE-D)
TYPE III 24-HOUR RAINFALL= 6.50 IN(100-YR STORM)
Prepared by Merrimack Engineering Services 26 Mar 01
HydroCAD 5 .11 000899 (c) 1986-1999 Applied Microcomputer Systems
SUBCATCHMENT 1 RUNOFF TO DESIGN POINT #1
PEAK= 1.40 CFS Q 12 .22 HRS, VOLUME= .13 AF
PERCENT CN SCS TR-20 METHOD
100 .00 79 EXIST. BRUSH - FAIR - H.S.G. "C" TYPE III 24-HOUR
TOTAL AREA .43 AC RAINFALL= 6.50 IN
SPAN= 10-20 HRS, dt= .1 HRS
Method Comment Tc (min)
TR-55 SHEET FLOW SURFACE RUNOFF 14 .1
Woods: Light underbrush n=.4 L=50 ' P2=3 .1 in s=.015
SHALLOW CONCENTRATED/UPLAND FLOW OVERLAND FLOW TOWARD WETLAND 5.4
Woodland Kv=5 L=200 ' s=.015 ' / ' V=.61 fps
CHANNEL FLOW SWALE TO DESIGN POINT #1 0.0
a=6 sq-ft Pw=.4' r=15 '
s=.02 '/ ' n=.06 V=21.3 fps L=20 ' Capacity=127.8 cfs
Total Length= 270 ft Total Tc= 19.5
SUBCATCHMENT 1 RUNOFF
RUNOFF TO DESIGN POINT #1
1 .4
1 .3 AREA= .43 AC
1 .2 Tc= 19.5 MIN
1 . 1 CN= 79
_ 1 .0 SCS TR-20 METHOD
.9 TYPE III 24-HOUR
U 8 RAINFALL= 6.50 IN
.7
3 .6 PEAK= 1 .40 CFS
012.22 HRS
1 5 VOLUME= . 13 AF
LL 4
.3
.2
1
0.0m N v in �0 m rn m
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (PRE-D)
TYPE III 24-HOUR RAINFALL= 6.50 IN(100-YR STORM)
Prepared by Merrimack Engineering Services 26 Mar 01
HydroCAD 5 .11 000899 (c) 1986-1999 Applied. Microcomputer Systems
SUBCATCHMENT 2 RUNOFF TO DESIGN POINT #2
PEAK= 3 .16 CFS @ 12 .21 HRS, VOLUME= .30 AF
PERCENT CN SCS TR-20 METHOD
15. 00 84 EXIST. BRUSH - FAIR - H.S.G. "D" TYPE III 24-HOUR
85 .00 79 EXIST BRUSH - FAIR - H.S.G. "C" RAINFALL= 6.50 IN
100.00 80 TOTAL AREA = .93 AC SPAN= 10-20 HRS, dt= .l HRS
Method Comment Tc (min)
TR-55 SHEET FLOW OVER VEGETATED SURFACE 14.1
Woods: Light underbrush n=.4 L=50 ' P2=3 .1 in s=.015
SHALLOW CONCENTRATED/UPLAND FLOW TOWARD THE WETLANDS 4.4
Short Grass Pasture Kv=7 L=250' s=.018 '/ ' V=.94 fps
CHANNEL FLOW INTO THE EXISTING WETLAND 0.0
a=6 sq-ft Pw=.4' r=15 '
s=.05 '/ ' n=.06 V=33 .68 fps L=20 ' Capacity=202 .1 cfs
Total Length= 320 ft Total Tc= 18.5
SUBCATCHMENT 2 RUNOFF
RUNOFF TO DESIGN POINT #2
3.0 AREA= .93 AC
2.8 Tc= 18.5 MIN
2.6 CN= 60
2.4
2.2 SCS TR-20 METHOD
2.0 TYPE III 24-HOUR
1 .8 RAINFALL= 6.50 IN
1 .6
1 .4 PEAK= 3. 16 CFS
O 1 .2 @ 12.21 HRS
-1 1 .0 VOLUME= .30 AF
� 8
.6
.4
2
0.0m N r) .T U) �0 r- m rn m
TIME (hour5)
Data for RTE 114 CAR WASH - NORTH ANDOVER (PRE-D)
TYPE III 24-HOUR RAINFALL= 6.50 IN(100-YR STORM)
Prepared by Merrimack Engineering Services 26 Mar 01
HydroCAD 5 .11 000899 (c) 1986-1999 Applied Microcomputer Systems
REACH 1 SUMMARY OF COMBINED FLOWS - SUBCATS #1 & 2
Qin = 4 .56 CFS @ 12.21 HRS, VOLUME= .43 AF
Qout= 4 .54 CFS @ 12 .22 HRS, VOLUME= .43 AF, ATTEN= 1%, LAG= .5 MIN
DEPTH END AREA DISCH
(FT) (SQ-FT) (CFS) 20 ' x 3 ' CHANNEL STOR-IND+TRANS METHOD
0 .00 0 .0 0 .00 SIDE SLOPE= .1 '/ ' PEAK DEPTH= .11 FT
.30 6.9 12 .96 n= .04 PEAK VELOCITY= 1.9 FPS
.60 15 .6 43 .91 LENGTH= 30 FT TRAVEL TIME = .3 MIN
.90 26.1 92 .30 SLOPE= .015 FT/FT SPAN= 10-20 HRS, dt=.l HRS
1.29 42 .4 183 .20
1.80 68.4 354.85
2 .40 105.6 642 .82
3 .00 150 .0 1035 .18
REACH 1 INFLOW & OUTFLOW
SUMMARY OF COMBINED FLOWS - SUBCATS # 1 & 2
4.5
4.0 20' x 3' CHANNEL
SIDE SLOPE= . 1 '/'
3 5 n=.04 L=30' S=.015
j 3.0 STOR-IND+TRANS METHOD
VELOCITY= 1 .9 FPS
`'
u 2.5
TRAVEL= .3 MIN
3 2.0 Qin= 4.56 CFS
O Qout= 4.54 CFS
J 1 .5 LA6= .5 MIN
LL
1 .0
.5
0.0m - N r*) v to �0 r` m rn m
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (PRE-D)
TYPE III 24-HOUR RAINFALL= 4.50 IN (10-yr Storm)
Prepared by Merrimack Engineering Services 26 Mar 01
HVdroCAD 5 .11 000899 (c) 1986-1999 Applied Microcomputer Systems
SUBCATCHMENT 1 RUNOFF TO DESIGN POINT #1
PEAK= .81 CFS @ 12 .23 HRS, VOLUME= .08 AF
PERCENT CN SCS TR-20 METHOD
100 .00 79 EXIST. BRUSH - FAIR - H.S.G. "C" TYPE III 24-HOUR
TOTAL AREA = .43 AC RAINFALL= 4 .50 IN
SPAN= 10-20 HRS, dt=.1 HRS
I
Method Comment Tc (min)
TR-55 SHEET FLOW SURFACE RUNOFF 14.1
Woods: Light underbrush n=.4 L=50 ' P2=3 .1 in s=.015 '/ '
SHALLOW CONCENTRATED/UPLAND FLOW OVERLAND FLOW TOWARD WETLAND 5.4
Woodland Kv=5 L=200 ' s=.015 '/' V=.61 fps
CHANNEL FLOW SWA.LE TO DESIGN POINT #1 0.0
a=6 sq-ft Pw=.4' r=15 '
s=.02 ' / ' n=.06 V=21.3 fps L=20 ' Capacity=127.8 cfs
Total Length= 270 ft Total Tc= 19.5
SUBCATCHMENT i RUNOFF
RUNOFF TO DESIGN POINT #1
.80
75 AREA= .43 AC
.70 Tc= 19.5 MIN
.65 CN= 79
.60
r, .55 SCS TR-20 METHOD
LO .50 TYPE III 24-HOUR
U 45 RAINFALL= 4.50 IN
.40
.35 PEAK= .81 CFS
o .30 C 12.23 HRS
-J 25 VOLUME= .08 AF
20
. 15
. 10
05
0.00� Q� m
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (PRE-D)
TYPE III 24-HOUR RAINFALL= 4.50 IN (10-yr Storm)
Prepared by Merrimack Engineering Services 26 Mar 01
HydroCAD 5 .11 000899 (c) 1986-1999 Applied Microcomputer Systems
SUBCATCHMENP 2 RUNOFF TO DESIGN POINT #2
PEAK= 1.85 CFS @ 12 .22 HRS, VOLUME= .17 AF
PERCENT CN SCS TR-20 METHOD
15 .00 84 EXIST. BRUSH - FAIR - H.S.G. "D" TYPE III 24-HOUR
85.00 79 EXIST BRUSH - FAIR - H.S.G. "C" RAINFALL= 4.50 IN
100.00 80 TOTAL AREA = .93 AC SPAN= 10-20 HRS, dt=.l HRS
Method Comment Tc (min)
TR-55 SHEET FLOW OVER VEGETATED SURFACE 14 .1
Woods: Light underbrush n=.4 L=50 ' P2=3 .1 in s=.015
SHALLOW CONCENTRATED/UPLAND FLOW TOWARD THE WETLANDS 4 .4
Short Grass Pasture Kv=7 L=250 ' s=.018 '/ ' V=.94 fps
CHANNEL FLOW INTO THE EXISTING WETLAND 0 .0
a=6 sq-ft Pw=.4' r=151
s=.05 ' / ' n=.06 V=33 .68 fps L=20 ' Capacity=202 .1 cfs
Total Length= 320 ft Total Tc= 18.5
SUBCATCHMENT 2 RUNOFF
RUNOFF TO DESIGN POINT #2
1 .8
1 .7 AREA= .93 AC
1 .6 Tc= 18.5 MIN
1 .5 CN= 80
1 .4
_ 1 .3 SCS TR-20 METHOD
,n 1 .2 TYPE III 24-HOUR
c,_ . i 1
u .0
RAINFALL= 4.50 IN
.9
3 .8 PEAK= 1 .85 CFS
o .7 G 12.22 HRS
J .6 VOLUME= . 17 AF
LL .5
.4
.3
.2
. 1
O1 m
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (PRE-D)
TYPE III 24-HOUR RAINFALL= 4.50 IN (10-yr Storm)
Prepared by Merrimack Engineering Services 26 Mar 01
HydroCAD 5.11 000899 (c) 1986-1999 Applied Microcomputer Systems
REACH 1 SUMMARY OF COMBINED FLOWS - SUBCATS #1 & 2
Qin = 2 .66 CFS @ 12 .22 HRS, VOLUME= .25 AF
Qout= 2 .64 CFS @ 12 .23 HRS, VOLUME= .25 AF, ATTEN= 1%, LAG= .5 MIN
DEPTH END AREA DISCH
(FT) (SQ-FT) (CFS) 20 ' x 3 ' CHANNEL STOR-IND+TRANS METHOD
0 .00 0.0 0.00 SIDE SLOPE= .1 '/ ' PEAK DEPTH= .06 FT
.30 6.9 12 .96 n= .04 PEAK VELOCITY= 1. 9 FPS
.60 15 .6 43 .91 LENGTH= 30 FT TRAVEL TIME = .3 MIN
.90 26.1 92.30 SLOPE= .015 FT/FT SPAN= 10-20 HRS, dt=.l HRS
1.29 42 .4 183 .20
1.80 68.4 354.85
2 .40 105 .6 642 .82
3 .00 150 .0 1035.18
REACH 1 INFLOW & OUTFLOW
SUMMARY OF COMBINED FLOWS - SUBCATS # 1 & 2
2.6
2,4 20' x 3' CHANNEL
z 2 SIDE SLOPE= . 1 '/'
n=.04 L=30' S=.015
2.0
r, 1 .8 STOR-IND+TRANS METHOD
C4- 1 6 UELOCITY= 1 .9 FPS
v 1 .4
TRAVEL= .3 MIN
:3 1 .2 Qin= 2.66 CFS
O 1 .13 Qout= 2.64 CFS
-i 8 LAG= .5 MIN
6
4
2
0.0CD - N f`"1 V 111 �D I� 8 Q) m
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (PRE-D)
TYPE III 24-HOUR RAINFALL= 3.10 IN
Prepared by Merrimack Engineering Services 26 Mar 01
HydroCAD 5.11 000899 (c) 1986-1999 Applied Microcomputer Systems
SUBCATCHMENT 1 RUNOFF TO DESIGN POINT #1
PEAK= .42 CFS @ 12 .24 HRS, VOLUME= .04 AF
PERCENT CN SCS TR-20 METHOD
100 .00 79 EXIST. BRUSH - FAIR - H.S.G. "C" TYPE III 24-HOUR
TOTAL AREA = .43 AC RAINFALL= 3 .10 IN
SPAN= 10-20 HRS, dt=.l HRS
Method Comment Tc (min)
TR-55 SHEET FLOW SURFACE RUNOFF 14 .1
Woods: Light underbrush n=.4 L=50 ' P2=3 .1 in s=.015
SHALLOW CONCENTRATED/UPLAND FLOW OVERLAND FLOW TOWARD WETLAND 5.4
Woodland Kv=5 L=200' s=.015 1/1 V=.61 fps
CHANNEL FLOW SWALE TO DESIGN POINT #1 0.0
a=6 sg-ft Pw=.4 ' r=15 '
s=.02 '/ ' n=.06 V=21.3 fps L=20 ' Capacity=127.8 cfs
Total Length= 270 ft Total Tc= 19.5
SUBCATCHMENT 1 RUNOFF
RUNOFF TO DESIGN POINT # 1
.40
AREA= .43 AC
.35 Tc= 19.5 MIN
CN= 79
30 SCS TR-20 METHOD
25 TYPE III 24-HOUR
U RAINFALL= 3. 10 IN
.20 PEAK= .42 CFS
� 15 e 12.24 HRS
-I UOLUME= .04 AF
IL
10
.05
0.0 00 _ N rn v rn 0 r, m rn m
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (PRE-D)
TYPE III 24-HOUR RAINFALL= 3.10 IN
Prepared by Merrimack Engineering Services 26 Mar 01
HydroCAD 5 .11 000899 (c) 1986-1999 Applied Microcomputer Systems
SUBCATCHMENT 2 RUNOFF TO DESIGN POINT #2
PEAK= .98 CFS @ 12 .22 HRS, VOLUME= .09 AF
PERCENT CN SCS TR-20 METHOD
15 . 00 84 EXIST. BRUSH - FAIR - H.S.G. "D" TYPE III 24-HOUR
85 .00 79 EXIST BRUSH - FAIR - H.S.G. "C" RAINFALL= 3 .10 IN
100 .00 80 TOTAL AREA = .93 AC SPAN= 10-20 HRS, dt=.l HRS
Method Comment Tc (min)
TR-55 SHEET FLOW OVER VEGETATED SURFACE 14 .1
Woods: Light underbrush n=.4 L=50 ' P2=3 .1 in s=.015
SHALLOW CONCENTRATED/UPLAND FLOW TOWARD THE WETLANDS 4.4
Short Grass Pasture Kv=7 L=250 ' s=.018 '/ ' V=.94 fps
CHANNEL FLOW INTO THE EXISTING WETLAND 0.0
a=6 sq-ft Pw=.4 ' r=15 '
s=.05 ' / ' n=.06 V=33 .68 fps L=20 ' Capacity=202 .1 cfs
Total Length-- 320 ft Total Tc= 18 .5
SUBCATCHMENT 2 RUNOFF
RUNOFF TO DESIGN POINT #2
.95
.90 AREA= .93 AC
,85 Tc= 18.5 MIN
.Be - CN= 80
.75
.70 SCS TR-20 METHOD
LO .65
60 TYPE III 24-HOUR
U .55 RAINFALL= 3. 10 IN
50
45 PEAK= .98 CFS
40
3 .35 C 12.22 HRS
-i .30 UOLUME= .09 AF
LL- .25
.20
. 15
10
05
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (PRE-D)
TYPE III 24-HOUR RAINFALL= 3.10 IN
Prepared by Merrimack Engineering Services 26 Mar 01
HydroCAD 5.11 000899 (c) 1986-1999 Applied Microcomputer Systems
REACH 1 SUMMARY OF COMBINED FLOWS - SUBCATS #1 & 2
Qin = 1.40 CFS @ 12 .23 HRS, VOLUME= .14 AF
Qout= 1.39 CFS @ 12 .24 HRS, VOLUME= .14 AF, ATTEN= 1%, LAG= .5 MIN
DEPTH END AREA DISCH
(FT) (SQ-FT) (CFS) 20 ' x 3 ' CHANNEL STOR-IND+TRANS METHOD
0.00 0 .0 0 .00 SIDE SLOPE= .1 '/ ' PEAK DEPTH= .03 FT
.30 6 .9 12 .96 n= . 04 PEAK VELOCITY= 1.9 FPS
.60 15.6 43 .91 LENGTH= 30 FT TRAVEL TIME _ .3 MIN
.90 26.1 92 .30 SLOPE= .015 FT/FT SPAN= 10-20 HRS, dt=.l HRS
1.29 42 .4 183 .20
1.80 68.4 354.85
2 .40 105.6 642 .82
3 .00 150 .0 1035.18
REACH 1 INFLOW & OUTFLOW
SUMMARY OF COMBINED FLOWS - SUBCATS # 1 & 2 .
1 .4
1 .3 20' x 3' CHANNEL
1 .2 SIDE SLOPE= . 1 '/'
1 . 1 n=.04 L=30' S=.015
_ 1 .0 STOR-IND+TRANS METHOD
LO .9 VELOCITY= 1 .9 FPS
U 8 TRAUEL= .3 MIN
:3 6 Qin= 1 .40 CFS
CD 'S Qout= 1 .39 CFS
LAG= .5 MIN
IL .4
.3
.2
. 1
0.em
TIME (hours)
I
POST-DEVELOPMENT DRAINAGE ANALYSIS
Proposed subsurface stormwater runoff detention facility is designed to mitigate
any increase in the peak rate of runoff due to pre- to post- development ground surface
conditions.
Pond #1 is a proposed subsurface detention system consisting of 66 precast
concrete box culvert structures laid out in two (2) separate groups at the rear of the site,
beneath the proposed pavement within the driveway and parking areas. These structures
will serve a"dual purpose" as an "upper-stage" flood storage facility for the higher
intensity storm events.
The surface runoff from the site to be collected by the site drainage system will be
discharged into these two groups using three pipe connections. For modeling purposes,
the runoff will be handled by one large subsurface detention"pond", combining facilities
"B" and "C" as a single ponding facility. Flood storage facility "A", a"lower-stage"
flood storage facility, will be used solely for accommodation of compensatory flood
storage as necessary to offset the proposed floodplain filling.
The stored water in facility `B" will flow into facility "C", through an 8" pipe.
Then, the combined volume of stored water in facility "C" will be discharged through a
10" pipe, which will have an 8" flap valve installed inside to prevent flood waters from
backing up into facility `B".
The total surface area of the combined detention system is calculated:
Facility "B": 22' x 115' = 2530 SF
Facility"C": 22' x 123' = 2706 SF
5236 SF
Use a factor of 0.9, to account for a 10% reduction in storage volume capacity due
to the volume of the concrete walls.
Therefore, the incremental storage volume is computed to be:
0.9 x 5236 = 4712 cu. ft. per vertical foot. The invert of the 10" outlet pipe from facility
"C" is set at 232.3. Add 0.05' to determine the invert of the 8" flap valve inside the 10"
pipe. Use an invert of 232.35 for the 8" flap valve at the outlet pipe from this structure.
Any potential for infiltration or exfiltration has been neglected from the analysis
due to minimal impact or significance. The structures will be installed with gasketed
joints to prevent or minimize any infiltration or exfiltration.
The roof drainage from the car wash facility will be collected and piped to a
"recharge" facility, and infiltrated over a period of up to three (3) days, depending on the
duration and intensity of the rainfall event.
Data for RTE 114 CAR WASH - NORTH ANDOVER (POST-D) Page 1
TYPE III 24-HOUR RAINFALL= 6.50 IN
Prepared by Merrimack Engineering Services 26 Mar 01
HydroCAD 5.11 000899 (c) 1986-1999 Applied Microcomputer Systems
WATERSHED ROUTING
14
12
1
11 � 13
OSUBCATCHMENT ❑ REACH POND I I LINK
SUBCATCHMENT 11 = DRIVEWAY & PARKING IN FRONT OF BLDG. -> REACH 1
SUBCATCHMENT 12 = DRIVEWAY AND PAVEMEMT AREAS -> POND 1
SUBCATCHMENT 13 = LAND RESTORATION & WETLAND REPLACEMENT -> REACH 1
SUBCATCHMENT 14 = PROPOSED BUILDING ROOF AREA -> POND 2
REACH 1 = COMBINED FLOWS—@ DESIGN POINTS #1 & #2 . . . ->
POND 1 = SUBSURFACE DETENTION FACILITY "B" & "C" -> REACH 1
POND 1 secondary = SUBSURFACE DETENTION FACILITY "B" & "C" -> REACH 1
POND 2 = ROOF DRAINAGE "RECHARGE" FACILITY -> POND 1
Data for RTE 114 CAR WASH - NORTH ANDOVER (POST-D)
TYPE III 24-HOUR RAINFALL= 6.50 IN (100-YR)
Prepared by Merrimack Engineering Services 27 Mar 01
HydroCAD 5.11 000899 (c) 1986-1999 Applied Microcomputer Systems
SUBCATCHMENT 11 PAVEMENT & LANDSCAPING AT ENTRANCE ROAD
PEAK= .64 CFS @ 12 .14 HRS, VOLUME= .06 AF
PERCENT CN SCS TR-20 METHOD
74 .00 74 AREAS TO BE LANDSCAPED & PLANTED TYPE III 24-HOUR
26.00 98 DRIVEWAY ENTRANCE AT RTE.114 RAINFALL= 6.50 IN
100.00 80 TOTAL AREA = .17 AC SPAN= 0-24 HRS, dt=.1 HRS
Method Comment Tc (min)
TR-55 SHEET FLOW TOWARD THE FRONT OF THE SITE 11.0
Grass: Dense n=.24 L=50 ' P2=3 .1 in s=.01 '/ '
SHALLOW CONCENTRATED/UPLAND FLOW FLOW TO DESIGN POINT #1 2 .4
Grassed Waterway Kv=15 L=300 ' s=.02 '/ ' V=2 .12 fps
Total Length= 350 ft Total Tc= 13 .4
SUBCATCHMENT 11 RUNOFF
PAUEMENT & LANDSCAPING AT ENTRANCE ROAD
60LAIUNFAA
. 17 AC
5513,4 MIN
50 = 80
.45 METHOD
.4024-HOUR
u 35 6.50 IN
.30 .64 CFS
3 .25 . 14 HRSOJ 20 = .06 AF
it
15
.05
0.00CD N Q 00 0o m N Q 0 M m N V
N N N
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (POST-D)
TYPE III 24-HOUR RAINFALL= 6.50 IN (100-YR)
Prepared by Merrimack Engineering Services 27 Mar 01
HydroCAD 5.11 000899 (c) 1986-1999 Applied Microcomputer Systems
SUBCATCHMENT 12 DRIVEWAY AND PAVEMEMT AREAS
PEAK= 3 .95 CFS @ 11.99 HRS, VOLUME= .32 AF
PERCENT CN SCS TR-20 METHOD
100 .00 98 AREAS TO BE PAVEMENT TYPE III 24-HOUR
TOTAL AREA = .61 AC RAINFALL= 6.50 IN
SPAN= 0-24 HRS, dt=.l HRS
1
Method Comment Tc (min)
TR-55 SHEET FLOW ACROSS DRIVEWAYS & PAVEMENT AREA .9
Smooth surfaces n=.011 L=50 ' P2=3 .1 in s=.01 ' / '
SHALLOW CONCENTRATED/UPLAND FLOW TO CB'S,THEN TO S.D.F. "B" & "C1T 1.6
Paved Kv=20 .3282 L=200' s=.01 ' / ' V=2 .03 fps
Total Length= 250 ft Total Tc= 2 .5
SUBCATCHMENT 12 RUNOFF
DRIUEWAY AND PAUEMEMT AREAS
3.8
3.6 AREA= .61 AC
3.4 Tc= 2,5 MIN
3.2 CN= 98
3.0
2.8 SCS TR-20 METHOD
� 2. TYPE III 24-HOUR
2.4
U 2.2 LRAALL= 6.50 IN
2.0
1 .8 PEA 3.95 CFS
3 1 .6 Lz 11 .99 HRS
2 LUME= .32 AF
1 ..8
.6
.4
.2
0.Om N V tD N m N V D N m N V
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (POST-D)
TYPE III 24-HOUR RAINFALL= 6.50 IN (100-YR)
Prepared by Merrimack Engineering Services 27 Mar 01
HydroCAD 5 .11 000899 (c) 1986-1999 Applied Microcomputer Systems
SUBCATCHMENT 13 LAND RESTORATION & WETLAND REPLACEMENT
PEAK= 1.44 CFS @ 12 .14 HRS, VOLUME= .13 AF
PERCENT CN SCS TR-20 METHOD
67.00 74 AREA TO BE LANDSCAPED TYPE III 24-HOUR
33 .00 80 AREA TO BE LANDSCAPED RAINFALL= 6.50 IN
100.00 76 TOTAL AREA = .42 AC SPAN= 0-24 HRS, dt=.l HRS
Method Comment Tc (min)
TR-55 SHEET FLOW OVER LANDSCAPED & NATURAL AREAS 11.0
Grass: Dense n=.24 L=50' P2=3 .1 in s=.01 ' / '
SHALLOW CONCENTRATED/UPLAND FLOW IN SWALE,WITHIN REPLACED WETLAND 2 .2
Grassed Waterway Kv=15 L=200 ' s=.01 '/ ' V=1.5 fps
CHANNEL FLOW IN SWALE ,TO DESIGN POINT #2 .2
a=8 sq-ft Pw=5' r=1.6'
s=.006 1 /1 n=.04 V=3 .94 fps L=40 ' Capacity=31.5 cfs
Total Length= 290 ft Total Tc= 13 .4
SUBCATCHMENT 13 RUNOFF
LAND RESTORATION 8 WETLAND REPLACEMENT
1 .4
1 .3LI
.42 AC
1 .213.4 MIN
i 1 = 76
1 .0 METHOD
t 924-HOUR
u .8 6.50 IN
� 61 .44 CFS
. 14 HRS
.5 . 13 AF
Li- .4
3
.2
. 1
O.Om N T tD m m N T tD N m N T
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (POST-D)
TYPE III 24-HOUR RAINFALL= 6.50 IN (100-YR)
Prepared by Merrimack Engineering Services 27 Mar 01
HydroCAD 5.11 000899 (c) 1986-1999 Applied Microcomputer Systems
SUBCATCHMENT 14 PROPOSED BUILDING ROOF AREA
PEAK= .76 CFS @ 11.98 HRS, VOLUME= .06 AF
PERCENT CN SCS TR-20 METHOD
100 .00 98 IMPERVIOUS ROOF SURFACE TYPE III 24-HOUR
TOTAL AREA = .12 AC RAINFALL= 6 .50 IN
SPAN= 0-24 HRS, dt= .1 HRS
Method Comment Tc (min)
TR-55 SHEET FLOW ACROSS MIDDLE OF ROOF .7
Smooth surfaces n=.011 L=50 ' P2=3 .1 in s=.02 1/1
SHALLOW CONCENTRATED/UPLAND FLOW ACROSS ROOF TO GUTTERS .7
Unpaved Kv=16.1345 L=100 ' s=.02 '/' V=2.28 fps
Total Length= 150 ft Total Tc= 1.4
SUBCATCHMENT 14 RUNOFF
PROPOSED BUILDING ROOF AREA
.75
70 AREA= , 12 AC
.65 Tc= 1 .4 MIN
.60 CN= 98
.55
50 SCS TR-20 METHOD
4� 45 TYPE III 24-HOUR
40 RAINFALL= 6.50 IN
.35 PEAK= .76 CFS
0 30 e 11 .98 HRS
J .25 VOLUME= .06 AF
L 20
. 15
. 10
.05
0.00m N V 0 N m N V tD W m N V
^ ^ ^ ^ ^ N N N
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (POST-D)
TYPE III 24-HOUR RAINFALL= 6.50 IN (100-YR)
Prepared by Merrimack Engineering Services 27 Mar 01
HydroCAD 5.11 000899 (c) 1986-1999 Applied Microcomputer Systems
REACH 1 COMBINED FLOWS. .@ DESIGN POINTS #1 & #2. . .
Qin = 3 .59 CFS @ 12 .15 HRS, VOLUME= .55 AF
Qout= 3 .52 CFS @ 12 .17 HRS, VOLUME= .55 AF, ATTEN= 2%, LAG= 1 .1 MIN
DEPTH END AREA DISCH
(FT) (SQ-FT) (CFS) 5 ' x 2 ' CHANNEL STOR-IND+TRANS METHOD
, 0 .00 0 .00 0 .00 SIDE SLOPE= .05 '/ ' PEAK DEPTH= .26 FT
.20 1. 80 1.79 n= .04 PEAK VELOCITY= 1.2 FPS
.40 5 .20 7.61 LENGTH= 20 FT TRAVEL TIME = .3 MIN
.60 10 .20 18.87 SLOPE= .01 FT/FT SPAN= 0-24 HRS, dt=.l HRS
.86 19.09 43 .73
1.20 34.80 97.59
1.60 59.20 198 .42
2 .00 90 .00 347.06
REACH 1 INFLOW 8 OUTFLOW
COMBINED FLOWS . . @ DESIGN POINTS # 1 & #2 . . .
3.6
3.4 5' x 2' CHANNEL
3.2 SIDE SLOPE= .05
3.0 2.8 n=.04 L=20' S=.01
2.6
2.4 STOR-IND+TRANS METHOD
O 2.2 UELOCITY= 1 .2 FPS
U 2.0 TRAVEL= .3 MIN
1 .8
1 .6 Qin= 3.59 CFS
0 1 .4 Qout= 3.52 CFS
J 1 .2 LAG= 1 . 1 MIN
.8
.6
.4
.2
0.0m N V 0 M m N V t0 DJ m N V
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (POST-D)
TYPE III 24-HOUR RAINFALL= 4.50 IN ( 10-YR)
Prepared by Merrimack Engineering Services 27 Mar 01
HydroCAD 5 .11 000899 (c) 1986-1999 Applied Microcomputer Systems
SUBCATCFMENT 11 PAVEMENT & LANDSCAPING AT ENTRANCE ROAD
PEAK= .38 CFS Q 12 .14 HRS, VOLUME= .03 AF
a
PERCENT CN SCS TR-20 METHOD
74 . 00 74 AREAS TO BE LANDSCAPED & PLANTED TYPE III 24-HOUR
26.00 98 DRIVEWAY ENTRANCE AT RTE.114 RAINFALL= 4.50 IN
100. 00 80 TOTAL AREA = .17 AC SPAN= 0-24 HRS, dt=.l HRS
Method Comment Tc (min)
TR-55 SHEET FLOW TOWARD THE FRONT OF THE SITE 11.0
Grass: Dense n=.24 L=50 ' P2=3 .1 in s=.01 1/ '
SHALLOW CONCENTRATED/UPLAND FLOW FLOW TO DESIGN POINT #1 2 .4
Grassed Waterway Kv=15 L=300 ' s=.02 '/ ' V=2 .12 fps
Total Length= 350 ft Total Tc= 13 .4
SUBCATCHMENT 11 RUNOFF
PAUEMENT 8 LANDSCAPING AT ENTRANCE ROAD
.36
.34 LYINFAe
. 17 AC
.323.4 MIN
.3e 88
.28
26 METHOD
4- .24 24-HOUR
20 4.50 IN
3 . 16 .38 CFS
O . 14 . 14 HRS-1 . 12 .03 AF
LL . 1 0
.08
.06
.04
.02
e.eem M m N V LJO N m N
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (POST-D)
TYPE III 24-HOUR RAINFALL= 4.50 IN ( 10-YR)
Prepared by Merrimack Engineering Services 27 Mar 01
HydroCAD 5.11 000899 (c) 1986-1999 Applied Microcomputer Systems
SUBCATCHMENT 12 DRIVEWAY AND PAVE14ETT AREAS
PEAK= 2 .72 CFS Q 11.99 HRS, VOLUME= .22 AF
PERCENT CN SCS TR-20 METHOD
100.00 98 AREAS TO BE PAVEMENT TYPE III 24-HOUR
TOTAL AREA = .61 AC RAINFALL= 4 .50 IN
SPAN= 0-24 HRS, dt=.l HRS
Method Comment Tc (min)
TR-55 SHEET FLOW ACROSS DRIVEWAYS & PAVEMENT AREA .9
Smooth surfaces n=.011 L=50 ' P2=3 .1 in s=.01 '/'
SHALLOW CONCENTRATED/UPLAND FLOW TO CB'S,THEN TO S.D.F."B" & "C" 1.6
Paved Kv=20 .3282 L=200' s=.01 '/ ' V=2 .03 fps
Total Length= 250 ft Total Tc= 2 .5
SUBCATCHMENT 12 RUNOFF
DRIUEWAY AND PAUEMEMT AREAS
2.6
AREA= .61 AC
2.4 Tc= 2.5 MIN
2.2 CN= 98
2.0
1 .6 SCS TR-20 METHOD
i 6 TYPE III 24-HOUR
RAINFALL= 4.50 IN
I .4
� 1 .2 PEAK= 2.72 CFS
0 1 .0 @ 11 .99 HRS
J 8 VOLUME= .22 AF
6
4
.2
O.Om N V lD OJ m N V tD 00 m N V
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (POST-D)
TYPE III 24-HOUR. RAINFALL= 4.50 IN ( 10-YR)
Prepared by Merrimack Engineering Services 27 Mar Ol
HydroCAD 5.11 000899 (c) 1986-1999 Applied Microcomputer Systems
SUBCATCHMENT 14 PROPOSED BUILDING ROOF AREA
PEAK= .52 CFS @ 11.98 HRS, VOLUME= .04 AF
PERCENT CN SCS TR-20 METHOD
100 .00 98 IMPERVIOUS ROOF SURFACE TYPE III 24-HOUR
TOTAL AREA = .12 AC RAINFALL= 4 .50 IN
SPAN= 0-24 HRS, dt=.1 HRS
Method Comment Tc (min)
TR-55 SHEET FLOW ACROSS MIDDLE OF ROOF .7
Smooth surfaces n=.011 L=50 ' P2=3 .1 in s=.02 1 /'
SHALLOW CONCENTRATED/UPLAND FLOW ACROSS ROOF TO GUTTERS .7
Unpaved Kv=16.1345 L=100' s=.02 / ' V=2 .28 fps
Total Length= 150 ft Total Tc= 1.4
SUBCATCHMENT 14 RUNOFF
PROPOSED BUILDING ROOF AREA
.50
AREA= . 12 AC
.45 Tc= 1 .4 MIN
.40 CN= 98
.35 SCS TR-20 METHOD
(n TYPE III 24-HOUR
U 30 RAINFALL= 4.50 IN
.25 PEAK= .52 CFS
3 .20 C� 11 .98 HRS
O
-i 15 VOLUME= .04 AF
. 10
.05
0.0 0� N V l0 O7 m N V 0 00 m N V
N N N
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (POST-D)
TYPE III 24-HOUR RAINFALL= 4.50 IN ( 10-YR.)
Prepared by Merrimack Engineering Services 27 Mar 01
HydroCAD 5 .11 000899 (c) 1986-1999 Applied Microcomputer Systems
POND 1 SUBSURFACE DETENTION FACILITY "B" & "C"
Qin = 2 .73 CFS @ 12 .00 HRS, VOLUME= .25 AF
Qout= 1. 03 CFS @ 12 .28 HRS, VOLUME= .24 AF, ATTEN= 62°%, LAG= 16 .5 MIN
ELEVATION AREA INC.STOR CUM.STOR STOR-IND METHOD
(FT) (SF) (CF) (CF) PEAK STORAGE = 2610 CF
232 .3 0 0 0 PEAK ELEVATION= 233 .2 FT
232 .4 2435 122 122 FLOOD ELEVATION= 238.0 FT
232 .8 2435 974 1096 START ELEVATION= 232 .3 FT
233 .0 4712 715 1810 SPAN= 0-24 HRS, dt=.l HRS
234 .0 4712 4712 6522 Tdet= 51.1 MIN ( .24 AF)
235.0 4712 4712 11234
236.0 4712 4712 15946
236.2 4712 942 16889
236.7 2277 1747 18636
236.8 10 114 18750
238 .0 10 12 18762
# ROUTE INVERT OUTLET DEVICES
1 P 232 .3 ' 8" CULVERT
n=.013 L=6' S=.0051/' Ke=.S Cc=.9 Cd=.6
POND 1 INFLOW & OUTFLOW
SUBSURFACE DETENTION FACILITY ''B" & "C"
2.6
2.4 STOR-IND METHOD
PEAK STOR= 2610 CF
2.2 PEAK ELEV= 233.2 FT
2.0
1 .6 Qin= 2.73 CFS
16 Gout= 1 .03 CFS
U 14 LAG= 16.5 MIN
3 1 .2
O 1 .0
J 8 I \
4 r �
r �
0.0' N V 0 N m I N V 0 00 m N V
N N N
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (POST-D)
TYPE III 24-HOUR RAINFALL= 4.50 IN ( 10-YR)
Prepared by Merrimack Engineering Services 27 Mar 01
HydroCAD 5 .11 000899 (c) 1986-1999 Applied Microcomputer Systems
POND 2 ROOF DRAINAGE "RECHARGE" FACILITY
Qin = 52 CFS @ 11.98 HRS, VOLUME= .04 AF
Qout= .30 CFS @ 12 .13 HRS, VOLUME= .03 AF, ATTEN= 43%, LAG= 8.8 MIN
ELEVATION AREA INC.STOR CUM.STOR STOR-IND METHOD
(FT) (SF) (CF) (CF) PEAK STORAGE = 745 CF
234 .4 0 0 0 PEAK ELEVATION= 236.7 FT
234 .5 324 16 16 FLOOD ELEVATION= 238 .4 FT
235 .5 324 324 340 START ELEVATION= 234 .4 FT
236 .5 324 324 664 SPAN= 0-24 HRS, dt=.l HRS
236.9 324 130 794 Tdet= 174 .2 MIN ( .03 AF)
237 .0 24 17 811
237.4 12 7 818
238.4 2 7 825
# ROUTE INVERT OUTLET DEVICES
1 P 236.5' 6" CULVERT
n=.013 L=10 ' S=.0031/ ' Ke=.5 Cc=.9 Cd=.6
2 P 234.4 ' EXFILTRATION
Q= .01 CFS at and above 234.5'
3 P 236.5 ' 6" CULVERT
n=.013 L=15 ' S=.021/ ' Ke=.5 Cc=.9 Cd=.6
POND 2 INFLOW S OUTFLOW
ROOF DRAINAGE ''RECHARGE'' FACILITY
.50
STOR-IND METHOD
.45 PEAK STOR= 745 CF
40 PEAK ELEV= 236.7 FT
35 Qin= .52 CFS
Qout= .30 CFS
u 30 LAG= 8.6 MIN
`J .25
o .20
J �
. 15 i
10 i
.05 i
0.00C9 N V to CO m N IT 0 Co C9 N V
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (POST-D)
TYPE III 24-HOUR RAINFALL= 3 .10 IN ( 2-YR)
Prepared by Merrimack Engineering Services 27 Mar 01
HydroCAD 5 .11 000899 (c) 1986-1999 Applied Microcomputer Systems
SUBCATCHMENT 11 PAVEMENT & LANDSCAPING AT ENTRANCE ROAD
PEAK= .20 CFS @ 12 .15 HRS, VOLUME= .02 AF
PERCENT CN SCS TR-20 METHOD
74 .00 74 AREAS TO BE LANDSCAPED & PLANTED TYPE III 24-HOUR
26.00 98 DRIVEWAY ENTRANCE AT RTE.114 RAINFALL= 3 .10 IN
100 .00 80 TOTAL AREA = .17 AC SPAN= 0-24 HRS, dt=.l HRS
Method Comment Tc (min)
TR-55 SHEET FLOW TOWARD THE FRONT OF-THE SITE 11.0
Grass: Dense n=.24 L=50 ' P2=3 .1 in s=.01 '/'
SHALLOW CONCENTRATED/UPLAND FLOW FLOW TO DESIGN POINT #1 2 .4
Grassed Waterway Kv=15 L=300 ' s=.02 '/ ' V=2 .12 fps
Total Length= 350 ft Total Tc= 13 .4
SUBCATCHMENT 11 RUNOFF
PAUEMENT & LANDSCAPING AT ENTRANCE ROAD
. 19
18 AREA= . 17 AC
• 17 Tc= 13.4 MIN
16 CN= 80
15
. 14 SCS TR-20 METHOD
�
. 12 TYPE III 24-HOUR
U . 11 RAINFALL= 3. 10 IN
. 10
09 PEAK= .20 CFS
o
.077 C 12. 15 HRS
-1 .06 UOLUME= .02 AF
05
04
.03
.02
01
e.e Om N V tD CO m N V D M m N V
N N N
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (POST-D)
TYPE III 24-HOUR RAINFALL= 3.10 IN ( 2-YR)
Prepared by Merrimack Engineering Services 27 Mar 01
HVdroCAD 5 .11 000899 (c) 1986-1999 Applied Microcomputer Systems
SUBCATCHMENT 12 DRIVEWAY AND PAVEMENT AREAS
PEAK= 1. 86 CFS Q 11.99 HRS, VOLUME= .15 AF
PERCENT CN SCS TR-20 METHOD
100 .00 98 AREAS TO BE PAVEMENT TYPE III 24-HOUR
TOTAL AREA = .61 AC RAINFALL= 3 .10 IN
( SPAN= 0-24 HRS, dt=.l HRS
Method Comment Tc min
TR-55 SHEET FLOW ACROSS DRIVEWAYS & PAVEMENT AREA .9
Smooth surfaces n=.011 L=50 ' P2=3.1 in s=.01 '/ '
SHALLOW CONCENTRATED/UPLAND FLOW TO CB'S,THEN TO S.D.F. "B" & "C11 1.6
Paved Kv=20.3282 L=200 ' s=.01 '/' V=2 .03 fps
Total Length= 25O ft Total Tc= 2 .5
SUBCATCHMENT 12 RUNOFF
DRIUEWAY AND PAUEMEMT AREAS
1 .8
1 .7 AREA= .61 AC
1 .6 Tc= 2.5 MIN
1 .5 CN= 98
1 .4
1 . SCS TR-20 METHOD
- 1 .2 TYPE III 24-HOUR
U 1 .6 RAINFALL= 3. 10 IN
9
3 .8 PEAK= 1 .86 CFS
0 7 C' 11 .99 HRS
-J .6 UOLUME= . 15 AF
LL .5
.4
.3
.2
. 1
N V tD M m N V lD M m N V --
'-
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (POST-D)
TYPE III 24-HOUR RAINFALL= 3 .10 IN ( 2-YR)
Prepared by Merrimack Engineering Services 27 Mar 01
HydroCAD 5.11 000899 (c) 1986-1999 Applied Microcomputer Systems
SUBCATCHMENT 13 LAND RESTORATION & WETLAND REPLACEMENT
PEAK= .38 CFS @ 12 .16 HRS, VOLUME= .04 AF
PERCENT CN SCS TR-20 METHOD
67 .00 74 AREA TO BE LANDSCAPED TYPE III 24-HOUR
33 .00 80 AREA TO BE LANDSCAPED RAINFALL= 3 .10 IN
100 .00 76 TOTAL AREA = .42 AC SPAN= 0-24 HRS, dt=.l HRS
Method Comment Tc (min)
TR-55 SHEET FLOW OVER LANDSCAPED & NATURAL AREAS 11.0
Grass: Dense n=.24 L=50 ' P2=3 .1 in s=.01 '/ '
SHALLOW CONCENTRATED/UPLAND FLOW IN SWALE,WITHIN REPLACED WETLAND 2 .2
Grassed Waterway Kv=15 L=200 ' s=.01 1/1 V=1.5 fps
CHANNEL FLOW IN SWALE ,TO DESIGN POINT #2 .2
a=8 sq-ft Pw=5' r=1.6 '
s=.006 1/ ' n=.04 V=3 .94 fps L=40 ' Capacity=31.5 cfs
Total Length= 290 ft Total Tc= 13 .4
SUBCATCHMENT 13 RUNOFF
LAND RESTORATION 8 WETLAND REPLACEMENT
.38
.36
34 AREA= .42 AC
.32 Tc= 13.4 MIN
30 CN= 76
.28
.26 SCS TR-20 METHOD
24 TYPE III 24-HOUR
.22 RAINFALL= 3. 10 IN
16 PEAK= .38 CFS
. 18
o . 14 e 12. 16 HRS
J . 12 UOLUME= .04 AF
LL 10
.08
.06
.04
.02
0.00� N V iD N m N V iD 0c m N V
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (POST-D)
TYPE III 24-HOUR RAINFALL= 3.10 IN ( 2-YR)
Prepared by Merrimack Engineering Services 27 Mar 01
HydroCAD 5.11 000899 (c) 1986-1999 Applied Microcomputer Systems
SUBCATCHMENT 14 PROPOSED BUILDING ROOF AREA
PEAK= .36 CFS @ 11.98 HRS, VOLUME= .03 AF
PERCENT CN SCS TR-20 METHOD
100 . 00 98 IMPERVIOUS ROOF SURFACE TYPE III 24-HOUR
TOTAL AREA = .12 AC RAINFALL= 3 .10 IN
SPAN= 0-24 HRS, dt=.l HRS
Method Comment Tc (min)
TR-55 SHEET FLOW ACROSS MIDDLE OF ROOF .7
Smooth surfaces n=.011 L=50 ' P2=3 .1 in s=.02 '/'
SHALLOW CONCENTRATED/UPLAND FLOW ACROSS ROOF TO GUTTERS .7
Unpaved Kv=16.1345 L=100 ' s=.02 '/' V=2.28 fps
Total Length= 150 ft Total Tc= 1.4
SUBCATCHMENT 14 RUNOFF
PROPOSED BUILDING ROOF AREA
.34
32 AREA= . 12 AC
.30 Tc= 1 .4 MIN
.28 CN= 98
.26
•24 SCS TR-20 METHOD
.22 TYPE III 24-HOUR
U 20 RAINFALL= 3. 10 IN
. IS
: 16 PEAK= .36 CFS
0 . 12 C 11 .98 HRS
VOLUME= .03 AF
LL . 1 0
.08
'06
.04
02
O.00m N V tD QJ m N V iD N m N V
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (POST-D)
TYPE III 24-HOUR RAINFALL= 3.10 IN ( 2-YR)
Prepared by Merrimack Engineering Services 27 Mar 01
HydroCAD 5.11 000899 (c) 1986-1999 Applied Microcomputer Systems
POND 1 SUBSURFACE DETENTION FACILITY "B" & "C"
Qin = 1.87 CFS Q 11.99 HRS, VOLUME= .16 AF
Qout= .76 CFS Q 12.20 HRS, VOLUME= .16 AF, ATTEN= 60%, LAG= 12 .1 MIN
ELEVATION AREA INC.STOR CUM.STOR STOR-IND METHOD
(FT) (SF) (CF) (CF) PEAK STORAGE = 1700 CF
1 232 .3 0 0 0 PEAK ELEVATION= 233 .0 FT
232 .4 2435 122 122 FLOOD ELEVATION= 238 .0 FT
232 .8 2435 974 1096 START ELEVATION= 232 .3 FT
233 .0 4712 715 1810 SPAN= 0-24 HRS, dt=.l HRS
234 .0 4712 4712 6522 Tdet= 54.7 MIN ( .16 AF)
235 .0 4712 4712 11234
236.0 4712 4712 15946
236.2 4712 942 16889
236.7 2277 1747 18636
236.8 10 114 18750
238 .0 10 12 18762
# ROUTE INVERT OUTLET DEVICES
1 P 232 .3 ' 8" CULVERT
n=.013 L=6' S=.0051/' Ke=.5 Cc=.9 Cd=.6
POND 1 INFLOW & OUTFLOW
SUBSURFACE DETENTION FACILITY "B'' & ''C''
i .s
1 .7 STOR-IND METHOD
1 .6 PEAK STOR= 1700 CF
1 .5 PEAK ELEV= 233 FT
1 .4
1 .3 Qin= 1 .87 CFS
� 1 .2 Gout= .76 CFS
U 1 .0 LAG= 12. 1 MIN
9
3 .8
0 •7
-i •6
LL-
.5
.3
.2 L
0.0m N V 0 M m/ N V 1 D co, m N V
N N N
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (POST-D)
TYPE III 24-HOUR RAINFALL= 3.10 IN ( 2-YR)
Prepared by Merrimack Engineering Services 27 Mar 01
HydroCAD 5.11 000899 (c) 1986-1999 Applied Microcomputer Systems
POND 2 ROOF DRAINAGE "RECHARGE" FACILITY
Qin = .36 CFS @ 11.98 HRS, VOLUME= .03 AF
Qout= .02 CFS @ 13 .40 HRS, VOLUME= .02 AF, ATTEN= 93%, LAG= 84.8 MIN
ELEVATION AREA INC.STOR CUM.STOR STOR-IND METHOD
(FT) (SF) (CF) (CF) PEAK STORAGE = 674 CF
1 234 .4 0 0 0 PEAK ELEVATION= 236.5 FT
234 .5 324 16 16 FLOOD ELEVATION= 238.4 FT
235 .5 324 324 340 START ELEVATION= 234 .4 FT
236.5 324 324 664 SPAN= 0-24 HRS, dt=.l HRS
236.9 324 130 794 Tdet= 251.3 MIN ( .02 AF)
237.0 24 17 811 .
237.4 12 7 818
238 .4 2 7 825
# ROUTE INVERT OUTLET DEVICES
1 P 236.5 ' 6" CULVERT
n=.013 L=10 ' S=.0031/' Ke=.5 Cc=.9 Cd=.6
2 P 234.4 ' EXFILTRATION
Q= .01 CFS at and above 234.5'
3 P 236.5 ' 6" CULVERT
n=.013 L=15 ' S=.021/' Ke=.S Cc=.9 Cd=.6
POND 2 INFLOW & OUTFLOW
ROOF DRAINAGE "RECHARGE'' FACILITY
.34 °
.32 STOR-IND METHOD
„30 PEAK STOR= 674 CF
.28 PEAK ELEV= 236.5 FT
.26
.24 Oin= .36 CFS
Lo
ti- .22 Qout= .02 CFS
u 20 LAG= 84.8 MIN
18
3 16
� . 14
J . 12
LL- . 10
.08
.06
.04
.32 - - ---'
0.00m N V tD OJ m N V 007 -CD- N - �Y
TIME (hour5)
Data for RTE 114 CAR WASH - NORTH ANDOVER (POST-D)
TYPE III 24-HOUR RAINFALL= 2.30 IN ( 1-YR)
Prepared by Merrimack Engineering Services 27 Mar 01
HydroCAD 5.11 000899 (c) 1986-1999 Applied Microcomputer Systems
SUBCATCHMENT 11 PAVEMENT & LANDSCAPING AT ENTRANCE ROAD
PEAK= .11 CFS Q 12 .16 HRS, VOLUME= .01 AF
PERCENT CN SCS TR-20 METHOD
74 .00 74 AREAS TO BE LANDSCAPED & PLANTED TYPE III 24-HOUR
26 . 00 98 DRIVEWAY ENTRANCE AT RTE.114 RAINFALL= 2 .30 IN
i 100 .00 80 TOTAL AREA = .17 AC SPAN= 0-24 HRS, dt=.1 HRS
Method Comment Tc (min)
TR-55 SHEET FLOW TOWARD THE FRONT OF THE SITE 11.0
Grass: Dense n=.24 L=50 ' P2=3 .1 in s=.01 ' / '
SHALLOW CONCENTRATED/UPLAND FLOW FLOW TO DESIGN POINT #1 2 .4
Grassed Waterway Kv=15 L=300' s=.02 '/ ' V=2 .12 fps
Total Length= 350 ft Total Tc= 13 .4
SUBCATCHMENT 11 RUNOFF
PAUEMENT 8 LANDSCAPING AT ENTRANCE ROAD
10 LRAINF
. 17 AC
.09 3.4 MIN
.08 80
.07 METHOD
Ln 4-HOUR
`U .06 .30 IN
U
.05 . 11 CFS
O 04 . 16 HRS03 .01 AF
.02
.01
0.0Om N �T W N m N V 0 (n m N V
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (POST-D)
TYPE III 24-HOUR RAINFALL= 2.30 IN ( 1-YR)
Prepared by Merrimack Engineering Services 27 Mar 01
HydroCAD 5.11_ 000899 (c) 1986-1999 Applied Microcomputer Systems
SUBCATCHMENT 12 DRIVEWAY AND PAVEMENT AREAS
PEAK= 1.37 CFS @ 11.99 HRS, VOLUME= .11 AF
PERCENT CN SCS TR-20 METHOD
100 .00 98 AREAS TO BE PAVEMENT TYPE III 24-HOUR
TOTAL AREA = .61 AC RAINFALL= 2 .30 IN
SPAN= 0-24 HRS, dt=.1 HRS
Method Comment Tc min
TR-55 SHEET FLOW ACROSS DRIVEWAYS & PAVEMENT AREA .9
Smooth surfaces n=.011 L=50' P2=3 .1 in s=.01 '/ '
SHALLOW CONCENTRATED/UPLAND FLOW TO CB'S,THEN TO S.D.F. "B" & "Cl, 1.6
Paved Kv=20 .3282 L=200' s=.01 '/' V=2 .03 fps
Total Length= 250 ft Total Tc= 2 .5
SUBCATCHMENT 12 RUNOFF
DRIUEWAY AND PAUEMEMT AREAS
1 .3
1 .2 AREA= .61 AC
Tc= 2.5 MIN
1 ' 1 CN= 98
1 .0
(n .9 SCS TR-20 METHOD
c, 8 TYPE III 24-HOUR
U 7 RAINFALL= 2.30 IN
� •6 PEAK= 1 .37 CFS
0 5 C' 11 .99 HR5
� 4 VOLUME= . 11 AF
3
.2
. 1
0.0CD N V w Co m N V 0 0o m N V
N N N
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (POST-D)
TYPE III 24-HOUR RAINFALL= 2.30 IN ( 1-YR)
Prepared by Merrimack Engineering Services 27 Mar 01
HydroCAD 5 .11 000899 (c) 1986-1999 Applied Microcomputer Systems
SUBCATCHMENT 13 LAND RESTORATION & WETLAND REPLACEMENT
PEAK= .19 CFS @ 12.18 HRS, VOLUME= .02 AF
PERCENT CN SCS TR-20 METHOD
67 .00 74 AREA TO BE LANDSCAPED TYPE III 24-HOUR
33 .00 80 AREA TO BE LANDSCAPED RAINFALL= 2 .30 IN
1 100 .00 76 TOTAL AREA = .42 AC SPAN= 0-24 HRS, dt=.l HRS
Method Comment Tc (min)
TR-55 SHEET FLOW OVER LANDSCAPED & NATURAL AREAS 11.0
Grass: Dense n=.24 L=50 ' P2=3 .1 in s=.01 ' /'
SHALLOW CONCENTRATED/UPLAND FLOW IN SWALE,WITHIN REPLACED WETLAND 2 .2
Grassed Waterway Kv=15 L=200 ' s=.01 '/' V=1.5 fps
CHANNEL FLOW IN SWALE ,TO DESIGN POINT #2 .2
a=8 sq-ft Pw=5' r=1.6'
s=.006 ' /' n=.04 V=3 .94 fps L=40 ' Capacity=31.5 cfs
Total Length= 290 ft Total Tc= 13 .4
SUBCATCHMENT 13 RUNOFF
LAND RESTORATION 8 WETLAND REPLACEMENT
18
17 LRAINF2
.42 AC
16 3.4 MIN
. 15 76
. 14
r . 13 METHOD
12 4-HOUR
u . 10 .30 IN
`J 09
.08 . 19 CFSO 07 . 18 HRS-J 06 .02 AF
.05
.04
03
.02
.01
0.0 0m N V 0 co m N Co m N V
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (POST-D)
TYPE III 24-HOUR. RAINFALL= 2.30 IN ( 1-YR)
Prepared by Merrimack Engineering Services 27 Mar 01
HydroCAD 5.11 000899 (c) 1986-1999 Applied Microcomputer Systems
SUBCATCHMENT 14 PROPOSED BUILDING ROOF AREA
PEAK= .26 CFS Q 11.98 HRS, VOLUME= .02 AF
PERCENT CN SCS TR-20 METHOD
100 .00 98 IMPERVIOUS ROOF SURFACE TYPE III 24-HOUR
TOTAL AREA = .12 AC RAINFALL= 2 .30 IN
SPAN= 0-24 HRS, dt=.l HRS
Method Comment Tc (min)
TR-55 SHEET FLOW ACROSS MIDDLE OF ROOF .7
Smooth surfaces n=.011 L=50 ' P2=3 .1 in s=.02 '/ '
SHALLOW CONCENTRATED/UPLAND FLOW ACROSS ROOF TO GUTTERS .7
Unpaved Kv=16.1345 L=100' s=.02 '/' V=2 .28 fps
Total Length= 150 ft Total Tc= 1.4
SUBCATCHMENT 14 RUNOFF
PROPOSED BUILDING ROOF AREA
.26
•24 AREA= . 12 AC
.22 Tc= 1 .4 MIN
.20 CN= 98
. 18 SCS TR-20 METHOD
LO . 16 TYPE III 24-HOUR
ti-
14 RAINFALL= 2.30 IN
12 PEAK= .26 CFS
O . 10 @ 11 .98 HRS
-� O8 UOLUME= .02 AF
.06
.04
.02
0.00, N V 0 CC) m N V 0 W m N V
N N N
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (POST-D)
TYPE III 24-HOUR RAINFALL= 2.30 IN ( 1-YR)
Prepared by Merrimack Engineering Services 27 Mar 01
HydroCAD 5.11 000899 (c) 1986-1999 Applied Microcomputer Systems
REACH 1 COMBINED FLOWS. .@ DESIGN POINTS #1 & #2. . .
Qin = .86 CFS Q 12 .18 HRS, VOLUME= .15 AF
Qout= . 86 CFS Q 12.20 HRS, VOLUME= .15 AF, ATTEN= 0%, LAG= 1.0 MIN
.DEPTH END AREA DISCH
(FT) (S -FT) (CFS) 5 ' x 2 ' CHANNEL STOR-IND+TRANS METHOD
' 0 .00 0.00 0.00 SIDE SLOPE= .05 '/ ' PEAK DEPTH= .10 FT
.20 1. 80 1.79 n= .04 PEAK VELOCITY= 1 .0 FPS
.40 5.20 7.61 LENGTH= 20 FT TRAVEL TIME = .3 MIN
.60 10.20 18.87 SLOPE= .01 FT/FT SPAN= 0-24 HRS, dt=.1 HRS
. 86 19.09 43 .73
1.20 34 .80 97.59
1.60 59.20 198.42
2 .00 90.00 347.06
REACH 1 INFLOW & OUTFLOW
COMBINED FLOWS . . @ DESIGN POINTS # 1 & #2 . . .
.85
.80 5' x 2' CHANNEL
.75 SIDE SLOPE= .05 '/'
.70 n=.04 L=20' S=,01
.65
.60 STOR-IND+TRANS METHOD
n .55 VELOCITY= 1 FPS
U .45 TRAUEL= .3 MIN
40 Qin= .86 CFS
0 39 Qout= .86 CFS
25 LAG= 1 MIN
.20
. 15
. 10
05
0.0 Om N r7 0 co m N P D 00 m N V
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (POST-D)
TYPE III 24-HOUR RAINFALL= 2.30 IN ( 1-YR)
Prepared by Merrimack Engineering Services 27 Mar 01
HydroCAD 5.11 000899 (c) 1986-1999 Applied Microcomputer Systems
POND 1 SUBSURFACE DETENTION FACILITY "B° & "CH
Qin = 1.38 CFS @ 11.99 HRS, VOLUME= .12 AF
Qout= .57 CFS Q 12 .19 HRS, VOLUME= .12 AF, ATTEN= 59%, LAG= 11. 9 MIN
ELEVATION AREA INC.STOR CUM.STOR STOR-IND METHOD
(FT) (SF) (CF) (CF) PEAK STORAGE = 1290 CF
1 232 .3 0 0 0 PEAK ELEVATION= 232 .9 FT
232 .4 2435 122 122 FLOOD ELEVATION= 238.0 FT
232 . 8 2435 974 1096 START ELEVATION= 232 .3 FT
233 .0 4712 715 1810 SPAN= 0-24 HRS, dt=.l HRS
234 .0 4712 4712 6522 Tdet= 58 .4 MIN ( .12 AF)
235 .0 4712 4712 11234
236.0 4712 4712 15946
236.2 4712 942 16889
236.7 2277 1747 18636
236.8 10 114 18750
238.0 10 12 18762
# ROUTE INVERT OUTLET DEVICES
1 P 232 .3 ' 8" CULVERT
n=.013 L=6' S=.0051/ ' Ke=.5 Cc=.9 Cd=.6
POND 1 INFLOW & OUTFLOW
SUBSURFACE DETENTION FACILITY ''B" & ''C''
1 .3 STOR-IND METHOD
1 .2 PEAK STOR= 1290 CF
1 . 1 PEAK ELEU= 232.9 FT
1 .0
c3 Qin= 1 .38 CFS
� Qout= .57 CFS
U 8 LAG= 11 .9 MIN
.7
:3 .6
O 5 �'
lL •4 i i
.3 i
.2 i
0. 0 QJ m I N OJ ® N V
TIME (hours)
Data for RTE 114 CAR WASH - NORTH ANDOVER (POST-D)
TYPE III 24-HOUR RAINFALL= 2.30 IN ( 1-YR)
Prepared by Merrimack Engineering Services 27 Mar 01
HydroCAD 5 .11 000899 (c) 1986-1999 Applied Microcomputer Systems
POND 2 ROOF DRAINAGE "RECHARGE" FACILITY
Qin = .26 CFS @ 11.98 HRS, VOLUME= .02 AF
Qout= .01 CFS @ 9.90 HRS, VOLUME= .01 AF, ATTEN= 96%, LAG= 0 .0 MIN
ELEVATION AREA INC.STOR CUM.STOR STOR-IND METHOD
(FT) (SF) (CF) (CF) PEAK STORAGE = 482 CF
234 .4 0 0 0 PEAK ELEVATION= 235.9 FT
234 .5 324 16 16 FLOOD ELEVATION= 238 .4 FT
235.5 324 324 340 START ELEVATION= 234.4 FT
236.5 324 324 664 SPAN= 0-24 HRS, dt=.1 HRS
236.9 324 130 794 Tdet= 271.7 MIN ( .01 AF)
237.0 24 17 811
237.4 12 7 818
238.4 2 7 825
# ROUTE INVERT OUTLET DEVICES
1 P 236.5' 6" CULVERT
n=.013 L=10 ' S=.0031/' Ke=.5 Cc=.9 Cd=.6
2 P 234.4 ' EXFILTRATION
Q= .01 CFS at and above 234.5 '
3 P 236.5 ' 6" CULVERT
n=.013 L=15 ' S=.021/' Ke=.5 Cc=.9 Cd=.6
POND 2 INFLOW & OUTFLOW
ROOF DRAINAGE "RECHARGE" FACILITY
.26
.24 STOR-IND METHOD
22 PEAK STOR= 482 CF
20 PEAK ELEU= 235.9 FT
. 18 Qin= .26 CFS
4- . 16 Qout= .01 CFS
u ' 14 LAG= 0 MIN
v
12
O . 10
LL .08
.06
.04
.02
- - - - - - - - --- - - - - - - -
0.00m N V to co m N V tD 00 m N V
TIME (hour5)
SUMMARY
As a result of the Pre and Post-Development Analysis, there is a net decrease or reduction in
the peak rate of runoff from the overall site for the 2, 10, and 100 year storms.. This is in
compliance, therefore, with Standard #2 of the Stormwater Management Policy and, in
addition, the Planning Board's Site Plan Regulations and Requirements.
The Pre-Development Analysis was done without the Floodway Analysis since the site runoff
would be discharging into the wetland or areas subject to flooding, regardless of the
floodplain elevation at any given time during the design storm event.
The Post-Development Analysis was done in conjunction with the Floodway Analysis in order to
determine the outlet flow from the subsurface drainage facilities while affected by the rise of
water in the floodplain, which results in a tail water effect, thereby reducing outlet flow capacity.
The following chart illustrates the resultant peak flow rates which occur during each storm
event at each Design Point and the Total, in summation:
PEAK FLOW RATES (CFS)
PRE-D POST-D DIFFERENCE
DESIGN DESIGN DESIGN DESIGN DESIGN DESIGN
STORM POINT POINT POINT POINT POINT POINT
EVENT #1 #2 TOTAL #1 #2 TOTAL #1 #2 TOTAL
100 Year 6.5") 1.4 3.16 4.56 0.64 2.88+/- 3.52 -0.76 -0.28+/- -1.04
10 Year 4.5" 0.81 1.85 2.66 0.38 1.77+/- 2.15 -0.43 -0.08 -0.51
2 Year(3.1") 0.42 0.98 1.4 0.2 1.13+/- 1.33 -0.22 +0.15+/- -0.07
1 Year 2.3") 0.22 0.54 0.76 0.11 0.75+ 0.86 -0.11 +0.21+/- +0.10
100 YEAR FLOODPLAIFN ELEVATION ANALYSIS
The calculated 100 year floodplain level between Route 114 and Chestnut Street, inclusive of
the property at 740 Turnpike Street, has been determined, by hydrological analysis, to be at an
elevation of 236.10, based on the results of the HEC-2 Floodway Analysis. The 100 year
floodplain elevation on the southerly side of Route 114 adjacent to Jasmine Plaza has been
previously determined to be at elevation 236.74. This difference in elevation of 0.64' is
indicative of a hydraulic gradient which occurs in order to maintain continuous flow through
the existing 42" RCP culvert under Route 114, during the peak of the 100 year storm event.
The culvert is functional during the submergence and tailwater condition, resulting in a
reduced rate of flow through the pipe at the peak of the area wide flooding.
FLOODPLAIN FILLING AND COMPENSATORY PLACEMENT VOLUME
The proposed volume of Floodplain Filling is based on calculation of the difference of the
grades between existing conditions and proposed development conditions. The existing
grades are determined based on an actual field survey of the property. The"Existing
Conditions" plan shows the spot shot elevations and the elevation contours. The development
plans show the filling required associated with the building siting and parking areas, confined
within proposed retaining walls. On this plan there is also a strip of land which is proposed to
excavated and reconstructed for both wetland replacement and land restoration, which will
provide a more aesthetic and natural appearance between the developed portion of the parcel
f and the existing wetland.
Within the 100 year floodplain, up to Elevation 236.1, an overall net increase of filling versus
removal volumes has resulted in provisions for on-site floodplain compensatory storage being
designed as part of the proposed site development.
The following chart shows a breakdown of areas indicative of the difference between pre and
post conditions on a vertical increment basis, as determined by planimetered and AutoCAD
measurements.
ELEVATION AREA(SO. FT.)
237 37,240 Filling
236 25,338 Filling
235 7,661 Filling
4,875 Removal 2,786 Filling
234 10,010 Removal
233 Not Computed
232 4,800 Removal
231.6 No Alteration
The following graph indicates a plot or depiction of the charted information, obtained from
the measurements indicated above, used to compute the volumes of wetland filling and
compensatory replacement. This is necessary in order to determine the size and number of
structures which will be needed for the placement of the flood storage facilities on the site.
JOB
ERI C ENGINEERINGVICES --
Professional Engineers • or
Land Sme s • SHEET NO. OF
66 Park Street y Planners �—�
ANDOVER, MASSACHUSETTS 01810 CALCULATED BY — oATE_ Feb Z 31 5 S 5
(508) 475-3555 CHECKED BY DATE
_ SCALE
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DETERMINE SIZE AND CAPACITY OF STAGED FLOOD STORAGE
FACILITIES FOR COMPENSATORY FLOODPLAIN REPLACEMENT
EL 236.1 - 235.3 (Upper Stage)
Volume= 0.8' x 27,000 + 16,000 = 17.200 Cu. Ft.
2
El = 235.3 - 234.74 (Lower Stage)
Volume= 0.55' x 1.6,000 + 1,000 = 4,675 Cu. Ft.
2
Upper Stage - Based on Concrete Systems Inc.
# of twin cell box culvert structures required @ 4' inside height by 2 F-10" overall width
invert of structures @ 232.3
invert of 6" PVC outlet pipe @ 232.4
each structure is 7' - 3 1/2" long, effective width of 19.83'
Determine Linear Feet of Twin Cell
Box Culverts and # of Structures Required:
17,200 Cu. Ft. = 19.83' x L 9236.1 - 232.4)
L =235'
Use 4 End Sections @ 6' - 6 '/2" Each (26.2')
and 29 Open Section @ 7' - 3 1/2" (211.5')
Total Area=21.83' x 239.4' = 5226.1 Sq. Ft.
Lower Stage - Based on Concrete Systems, Inc.
Use 4' inside height structures,
21'-10" overall width(9' - 4" outside width)
invert of structures at 232.3
invert of 6" PVC outlet pipe @ EL = 232.4
Determine Liner Feet of Twin Cell
Box Culvert System and Total Number of Structures Required:
4675 Cu. Ft. = 19.83' X L x (235.3 - 232.4)
L= 82'
Use 2 End Sections @ 6' - 6 1/2" Ea. (13.l')O and
10 Open Sections @ 7' - 3 1/2" Ea. (73')
Total Length= 86.F
Total Area= 21.83' x 86.P = 1880 Sq. Ft.
THE HAESTAD'S FLOW-MASTER I PROGRAM WAS USED FOR DETERMINATION
OF FLOW CHARACTERISTICS AT THE STORMWATER DETENTION AND FLOOD
STORAGE FACILITIES.
(Refer to the "Outflow Capacities" Charts for the resultant flow characteristics).
I. The outflow from these facilities will be discharged through a 12" RCP drain pipe into
a rip-rap area, then into and through a 3' wide grass-lined treatment swale to the
wetland.
A. The 12" RCP pipe is 9 feet in length, with a slope of 0.5%, and n= 0.015, full flow
capacity is 2.34 cfs, with V= 3.11 FPS, and Depth= 0.91 feet.
From the post-development analysis, the outflow from these facilities reached a
maximum flow rate of 0.90 cfs, which occurred during the 10 year storm.
B. The grass swale is 3' wide with 4:1 side slopes and a slope of 0.5%, and n= 0.15
(short grass). At a maximum computed flow rate of 0.90 cfs, the velocity will be 0.36
FPS, at a depth of 0.52' in the swale.
II. The Flood Storage Facilities will be filled to capacity as the floodplain level rises
during the 100 year storm event. There will be 2-12" RC pipes provided for this
purpose, at each facility i.e. "high" and"low" stage. The "low" stage has 2 pipes at
slope= 0.6%, approximately 12 LF each. At full flow, the peak inflow rate is 2.40 cfs,
or 4.8 cfs for both pipes.
The "high" stage has 2 pipes at slope = 1.2%, approximately 17 LF each. At full flow,
the peak inflow rate is 3.60 cfs, or 7.2 cfs for both pipes.
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SOIL. TYPES
PARENT DEPTH
MATERIAL TO HIGH HYDROLOGIC
PERMEABILITY WATER SOIL
SYMBOL NAME TEXTURE (IN/HR) (FT) GROUP
MC Medisaprists - - - D
(deep)
RdA Ridgebury F.S.L. <0.2 0-1.5 C
Wg Whitman F.S.L. <0.2 0-0.5 D
WrC Woodbridge F.S.L.. <0.2 1-3 C
MC SO11L- Consists of nearly level, very poorly drained deposits of organic material, extends
to depth of 64 inches or more, generally is black to very dark grayish brown decomposed
organic matter. Permeability is moderate to rapid, frequently flooded, with a seasonal high
water table at or near the surface.
RdA 5OM - Consists of cheep, nearly level, poorly drained soil along drainageways. Subsoil
is fine sandy loam, olive and olive brown, mottled, and firm, to a depth of 60 inches or'more,
slow permeability in substratum, seasonal high water at or near surface.
Wg S01L, -,Consists of deep, nearly level, very poorly drained sandy loam to a depth of 60
inches or more, subsoil is firm, gray, and mottled. Slow permeability in substratum. Seasonal
high water table at or near surface.
WrC SOIL. - Consists of deep, moderately well drained subsoil of friable fine sandy loam,
yellowish brown to olive brown, mottled, slow permeability in the substratum, with a seasonal
high water table at 1.5 to 3 feet.
rr. Appendix A. RUNOFF CURVE NUMBERS
0
Runoff curve numbers for urban areas,
Cover descriptio Curve numbers for
description Curve
soil group_
Average percent
Cover, type and hydrologic condition iMpervious area= A
C D
Fully developed urban areas (vegetation established)
Open space (lawns, parks, golf courses, cemeteries, Pf�E_D
e tc.)3:
Poor condition (grass cover < 60%) ............. 68
Fair condition (grass cover 50% to 75%)........... 79 8 - S9
Good condition (grass cover > 75% 49 '9 79 81
Impervious areas:
Paved parking lots, roofs, driveways, etc. 5T'-D
(excluding right-of-way). ..................:.. ... 98 98 Streets_and roads: 98 98
Paved; curbs and storm sewers (excluding
right-of-way). 98
Paved; open ditches (including right-of-way) . 98 98 95
Gravel (including right-of-way) ............ ...... 83 89 92 93
Dirt (including right-of-way) ... .... 76 85 89 91
Western desert urban areas: 72 82 87 89
Natural desert landscaping(pervious areas only)a...
Artificial desert landscaping 63 77 85 88
p' g (impervious weed
barrier, desert shrub with 1- to 2-inch sand
or gravel mulch and basin borders). ............. 96
Urban districts: 96 96 96
Commercial and business....... ............. 85 89
Industrial. . 92 94 95
Residential districts by average lot size: ?2 81 88 91 93
118 acre or less (to%v-n houses)................ 65 77
1/4 acre ..... 85 90 92
113 acre ......................................... 38 61 75 83 S7
1/2 acre .... ................................ .... 30 57 72 81 86
1 acre .................. 25 54 70 80 85
20
2 acres .......................................... 12 51 68 79 84
46 65 77 82
Developing urban areas
Newly graded areas (pervious areas only,
no vegetation)s. 77
Idle lands (CN's are determined using cover types 8G 91 94
similar to those in table 2.20.
'Average runoff condition,and I, s 0.2S.
Me average percent impervious area shown was used to develop the composite CN's.Other assumptions are as follomw im.pervious ar•ew
are directly connected to the drainage system, impervious areas have a CN of 98, and perviou:c areas are considered equivalent to open
Space in goal hydrologic condition.C\^s for other combinatiors of condiLlons nray W menputed using figure 21 or 2-4.
'CN's shown Are equivalent to those of pasture. Composite CN's may be computed for other combinations of open space cover type.
'Composite CN's for natural desert landscaping should be computed using figures 2-3 or 24 based on the impervious area per•centarge(CN
98)and the pervious area CN.The pervious area CN's are assumed equivalent to desert shrub in pour hydrologic condition.
'Composite CN's to use for the design of temporary measur•gs during grading and construction should be computed using fignr•e 2.3 or 24,
based on the degree of development(impervious area percentage)and the CN's for the newly graded pervious areas.
This appendix reprinted from S.C.S. fR-55, revind 1986.
A-1
�v
o
O VALVEe Or THE ROVOHNEss ComrrrCIENT n (continued)
-"s VALUES Or TIIE 110VOHPfCEE CoCrrICIE VT n (continued) C1
bType of channel and descriptionTMinimum7NormalimumType of channel and description ,MinimumA°ormnl .Maximum
er C. E:cwvATEa oR DREoota ^a. Earth,straight and uniform b. Alountnin streams, no vegetation in z
I. Clean,recently completed020 channel, banks usually steep, trees2. Clem,alter weathering . .0290.025 and brush along banks submerged at z
3. Gravel,uniform section,clean 0.022 0.025 Q_Q3® high stage--
um 0
4. With short i. Bottom:'gravcla, cobbles, and fen 0.430 0.010
grass,few weeds 0.022 0.027 0.033 boulders 0.050
b. Earth,winding and sluggish
1. No vegetation Bottom:cobbles with large boulders 0.040 0.050
0.023 0.025 0.030 D-2. Flood plains 0.070
z 2. Grass,some weeds 0.025 0.030 0.033
3. Den weeds or aquatic plants in 0.030
Den." 0.035 0.040 a• pasture,no brush
e
I.. Short grate (�" deep channels 0025 0
4. Earth bottom and rubble sides 2• High grass 0.035
0.028 0.030 0.035 . .030 b.'Cultivated areas 0.030 0.035 0.050 5. Stony bottom and weedy banks 0.025 0.035 0.040
6. Cobble bottom and clean sides I. M crop 0.020
0.030 0.040 0.050 2: 17attire row crops ' 0-030 0.0-l0 W
C. Dragline�cavated or dredged ���� 0.0_3 0.035 O.OaS r[° 1. No vegetation 3. P.fature field crops riq
0.025 0.028 0.033 c. Brush 0.030 0.040 1 0.050
0 2. Light brush on banks 0.035 0.050 0.080 .-.
d. Rock cuts 1. Scattered brush,heavy needs 0.035
2. Light brush and trees, in winter 0.050 0.070
>e I. Smooth and uniform 0.025 0.035 0.040 0-:bt35 0.030 0.060 �.2. Jagged and irregular 0.035 0.090 0.050 3• Light brush and trees,in summer
4. Medium to dense brush,in winter 4' 0.030
a. Channels not maintained, weeds and O.OaS 0.070 0.110
brush uncut S. Medium to dense brush,in summer 0.070 a t d. Trees 0.100 0.160
1. Dense weeds,high as flow depth 0.050 0.080 0.120 1. Ucnsc willows,summer,straight 0,110
f9 2. Clean bottom,brush on sides 0.040 0.150
3. Same,highest s 0.050 0.080 2. Cleared land with tree stun 0.200
050
E g cage of Bow 0.045 0.070 0.110 sprouts pa, no 0.0.30 O.OaO 0.050 4. Dense brush,high stage 0.0$0 0.100 0.190
D. NATURAL STREAUS D. Same assbove,ut but with heavy 0.050 0.060 0.050
,t D-1. Minor streams (top width at flood stage growth of sprouts
3 trees,little undergrowth,
<100 ft) 4• Heavy stand of timber,a few down
0.080 0.100 0.120
W a. Streams on plain flood stage
1. Clean,straight,full stage,no rifts or 0.025 0.030 0.033 below branches
deep pools 5. Same as above,but with flood stage
2. Same as above,but more atones and teaching branches g 0 Y00 0.120 0.I C0
`ems weeds 0.0.10 0.035 .0.040 s� major streams (top width at flood stage
3. Clean, winding, some pools and 0 a 100 ft). The n value is less than that
shoals .033 0.040 0.015 for minor streams of similar description,
4. Same as above,but some weeds and 0.035 0.045 because banks offer leas effective resistance.
E stones 0.050 a• Regular section with no boulders or 0.025
= b. Same as above lower a brush 0.060
E , more 0.040 0.048 0.055 b. Irregular and rough section
ineffective elopes and sections 1 0.035 0.100
6. Same as 4,but more stones 0.045 3.050 ! 0.060
1r. 7. Sluggish reaches,weedy,deep PAL+ 0.M 0.070 .! r 080
8. Very weedy reaches,deep pools,or 0.075 0.100 i 0.150
v+ floodways with heavy stand of tim- i
ber and underbrush I
Appendix A: RUNOFF CURVE LUMBERS (continued)
Runoff curve numbers for grid and semiarid rangeland,'
Curve number: for
Covet description hydrologic soil group_
Hydrologic
Cover type conditionz A3 g C D
--herbaceous—mixture of grass, weeds, and Poor 80 87 93
1mv-growing brush, with brush the Fair 71 81
minor element. Good 62 74 89
Oak-aspen—mountain brush mixture of oak brush, Poor 66 74 79
aspen, mountain mahogany, bitter brush, maple, Fair 48 57 63
and other brush. Good 30 41 48
Pinyon-juniper—pinyon,juniper, or both; Poor 75 85 $9
gra:,s umlerstory. Fair
5S 73 80
Good 41 61 71
sagr.brusl; %with grass understory. Poor 67 80 85
Fair 51 63 70
Good 35 47 55
Desert shrub—major plants include saltbush, Poor 63 77 85 88
greasewood, creosotebush, blackbrush, bursage, Fair 55 72 81 86
palo verde, mesquite, and cactus. Good 49 68 79 84
Avea age runoff condition, and Ia = 0.25. For range in humid regions, use table 2-2c.
'Pw r: <30q ground cover(litter,grass,and brus', overstory).
Fair: .30 to 70% ground cover.
l,rwl: >70% grotzsr(I cover•.
'Curet., numbers for group A have been develop!:I only for-desert shrub.
This appendix reprinted from S.C.S. TR-55, revised 1986.
A-4
Appendix A: RUNOFF CURVE NUMBERS (continued)
Runoff curve numbers for other agricultural lands,
Curve numbers for
Cover description hYdrulogic soil group_
Hydrologic
Cover type condition q B
C D
Pasture, grassland, or range—continuous
Poor
forage for g-razing.2 68 79 86 89
Fair 49 69 19 n rT7--)
Good 39 61 80
Meadow—continuous grass, protected from — 30
58
grazing and gener ally moved for hay. 71 78
Brush—brush-weed-grass mixture with brush Poor
the major element.o 48 U7 77 83
Fair 35 56 70 77
Good 48 65 73
Woods—grass combination (orchard Poor
or tree farm).S 57 73 82 86
Fair 43 65 16 82
Good 32 58 72 79
Woodsy
Poor 45 66 77 93
Fair 36 60 73 79
Good 430 55 70 77
Farmsteads—buildings, lanes, driveways, — 59 74
and surrounding lots. 82 86
'Average runoff condition,and I = 0.2S.
2/'uu «Ok ground cover or heavily grazed with no mulch.
Fair: 50 to 75% ground cover and not heavily grazed.
Good: >75%ground cover and lightly or only occasionally grayed.
'four. <50%,ground cover.
F"air: 50 to 75%ground cover.
Gaud: >75%ground cover•.
'Actual curve number is less than 30; use CN =30 for runoff computations.
'CN's shown were computed for areas with SVI, %voucls and 50%grass(pasture)cover. Other combination:of conditions may be computed
from the CN's fur woods and pasture.
"Poor. Forest litter, .mall trees, and brush are destroyed by heavy grazing or regular burning.
Farr: woods are gnazed but not burned,and some forest litter covers the soil.
Guwk Woods are protected from grazing,and litter and brush adequately cover the soil.
This appendix reprinted from S.C.S. TR-55, revised 1996.
A-3
Appendix A: RUNOFF CURVE NUMBERS
Runoff curve numbers for urban arensr
Cure numbers for
Cover description hydrologic soil gr•uup—
Average percent
Cover type and hydrologic cmi-dition impervious areal A PS C D
Fully developed urban areas (vegetation established)
Open space (lawns, parks, golf courses, cemeteries, pRq-D
etc.)":
Poor condition (grass cover < 50%) .......,.,_, S8 79 8
ss
Fair condition, (grass cover 50% to 7590)........... 49 r39 79 S4 j Good condition (grass cover > 75%) ........ 39 GI
Impervious areas:
Paved parking lots, roofs, driveways, etc. 5r-p
.(excluding right-of-way).
Streets and toads: ......................... 98 98 98 98
Paved; curbs and storm sewers (excluding
right-of-way).................................. 98 98 9S
Paved, open ditches (including right-of-way) ....... 9S
Gravel (including right-of-way) ................... 83 89 92 93
Dirt (including right-of-way) .......... t0 91
Western desert urban areas 72 82 87 89
ANatural desert landscaping(pervious areas only)'... 63 77 85 38
rtificial desert landscaping(impervious weed
barrier, desert shrub with 1• to 2-inch sand
or gravel mulch and basin borders). .............. 96 96
Urban districts: 96 96
Commercial and business.......................... 85 89 92
Industrial. 94 95
Residential districts by average lot size: 72 81 88 91 93
1/8 acre or. less (town houses)......... ....... 65 77 85 90 1/4 acre ....................................... 38 61 75 92
1/3 acre 83 S7
1/2 acre ....
1 acre ....... ....... O 54 70 80 85
2 acres ........................................ 12 46 65 77 82
Developing urban areas
Newly graded areas (pervious areas only,
no vegetations. 77 86 91 94
Idle lands(CN's are determined using cover types
similar to those in table 2-20.
'Average runoff condition, and 1. - 0.2S.
°The average percent impervious area shown was used to develop the composite CN's. Other assumptions are as follows-impervious areas
are directly connected to the drainage system, impervious areas have a CN of 98, and pervious areas are considered equivalent to open
space in good hydrologic condition. C\";for other combinations of ecandiliuns nuay tie computed using figure 243 or 2.4.
°CN's shown are equivalent to those of pasture. Composite CN's may be computed for other combinations of open space cover type.
`Composite CN's for natural desert landscaping should be computed using figures 23 or 24 based on the impervious area percentage(CN
a 98)and the pervious area CN. The pervious area CN's are assumed equivalent to desert shrub in pour hydrologic condition.
'Composite CN's to use for the design of temporary measures during grading and construction should be computed using fipire 23 or 24.
based on the degree of development(impervious area percentage)and the CN's for the newly graded pervious areas.
This ameradix reprinted from S.C.S. TR-SS, revised 1996.
-1
Appendix G: VELOCITY FACTORS
The TR-55 Shallow Concentrated Flow procedure and the NEH-4 Upland Method are both published as
a chart of velocity vs. slope for various surfaces. Both charts are based on the same equation (see page
4) and make use of a velocity factor, Kv, determined by the surface type. HydroCAD provides the
following predefined surface types for use with this equation.'
The first two surfaces (paved and unpaved) are the basis for TR-55 Figure 3-1, and the factors are taken
from TR-55, Appendix F [11 p.F-11. The remaining surfaces are taken from NEH-4 Figure 15.2
[10 p.15-81 with the factors derived from that chart. (Some descriptions have been abbreviated.) For
other surfaces or conditions, HydroCAD also allows the direct entry of K,
Surface Description Kv
Paved 20.3282
Unpaved 16.1345
Grassed Waterway 15.0
Nearly Bare & Untilled 10.0
Cultivated Straight Rows 9.0
Short Grass Pasture 7.0
Woodland 5.0
Forest w/Heavy Litter 2.5
Thew factors am for a fractional slope(rise/run) and a velocity in fed per second.
A-19
Appendix F: SHEET FLOW ROUGHNESS COEFFICIENTS
When using the TR-55 Sheet Flow procedure for calculating time of concentration [I I p.3-3], HydroCAD
provides the following table of roughness coefficients. This information is taken directly from TR-55
Table 3-1, with slight abbreviation of the descriptions. If you decide to substitute other roughness
coefficients, note that these values are specifically for sheet flow, and may be larger than the regular
Manning's number for a comparaMe surface.
Surface Description n
Smooth surfaces .011
Fallow .05
Cultivated: Residue< =20% .06
Cultivated: Residues 20% .17
Grass: Short .15
Grass: Dense .24
Grass: Bermuda .41
Range 13
Woods: Light underbrush .40
Woods- Dense underbrush .80
A-18
Trapezoidal Channel Analysis & Design
Open Channel - Uniform flow
Worksheet Name : Grass-lined Swale
Description: Outflow from Drainage Facilities to Wetland
Solve For Discharge
Given Constant Data,
Bottom Width. . . . . . . 3 .00
Z-Left . . . . . . . . . . . . . 4 . 00
Z-Right . . . . . . . . . . . . 4 . 00
Marinings 'n' . . . . . . . 0 . 150
Channel Slope . . . . . . 0 . 0050
Variable Input Data Minimum Maximum Increment- Jay
Channel Depth 0-.0OF 0.70 0 . 10
VARIABLE COMPUTED COMPUTED
Bottom Z-Left Z-Right Mannings Channel Channel. �-Channel
_Velocity
Width (H:V) (H:V) 'n' Slope Depth Discharge fps
ft ft/ft ft cfs
Unable to compute this instance .
3 . 00 4 .00 4 . 00 0 .150 0 . 0050 0 . 10 0 .05 0 . 14
3 . 00 4 . 00 4 .00 0 .150 0 .0050 0 .20 0 . 16 0 . 21
3 . 00 4 .00 4 .00 0 .150 0 . 0050 0 . 30 0 . 33 0 .26
3 . 00 4 . 00 4 . 00 0 .150 0 . 0050 0 .40 0 . 57 0 . 31
3 . 00 4 .00 4 . 00 0 .150 0 .0050 0 .50 0 . 87 0 . 35
3 . 00 4 . 00 4 . 00 0 .150 0 . 0050 0 . 60 1 . 25 0 .39
3 . 00 4 . 00 4 . 00 0 .150 0 . 0050 0 . 70 1 . 70 0 .42
/Q /))dXiMurrl oLcfT/aGtJ /a / C ,9CFS
Gvocc/d resu.lr- in
P•S• In Me Swa/eJ uih/C/7 12OS a
perm 1sSi 6/e Ve%c//Y o f S fPS
Open Channel Flow Module, Version 3 . 16 (c)
Haestad Methods, Inc . * 37 Brookside Rd * Waterbury, Ct 06708
Circular Channel Analysis & Design
Solved with Manning' s Equation
Open Channel - Uniform flow
Worksheet Name : Outflow Capacities
Description: Inflow from Floodplain to Storage Facilities
Solve For Actual Depth
Given Constant Data,
Diameter. . . . . . . . . . . 1 . 00
Slope . . . . . . . . . . . . . . 0 . 0060 "LOW) STAGE
Mannings n. . . . . . . . . 0 . 015
Variable Input Data Minimum Maximum Increment By
Discharge 0. 00 z 4OF --__0 30 =
VARIABLE COMPUTED COMPUTED COMPUTED
Diameter Charmer Mannings Discharge Depth Velocity Capacity
ft Slope 'n' cfs ft fps Full
ft/ft cfs
Unable to compute this instance.
1..00 0 .0060 0 .015 0 . 30 0 .24 2 .08 2 .39
1.00 0 _0060 0 .015 0 .60 Q_34 2 .53 2.39
1 . 00 0 .0060 0 .015 0 . 90 0 .43 2 .83 2 .39
1 .00 0 .0060 0 . 015 1 . 20 0 .50 3 . 05 2 .39
1 . 00 0 .0060 0 .015 1 . 50 0 .57 3 .22 2 .39
1 .00 0 .0060 0 .015 1 _80 0 .65 3 .34 2 .39
1 . 00 0 .0060 0 .015 2 . 10 0 .73 3 .43 2 .39
1 .00 0 .0060 0 .015 2 .40 0 . 82 3 .47 2 .39
Open Channel Flow Module, Version 3 . 16 (c)
Haestad Methods, Inc . * 37 Brookside Rd * Waterbury, Ct 06708