HomeMy WebLinkAboutBLD2004-00449 Stormwater Management Plan w
STORM DRAINAGE REPORT
Owner:
- Daniel and Victoria O'Donnell -
3016 38th Ave. SW
Seattle, WA 98126
Subject Property:
333 Fager Hill Rd.
Port Townsend, WA 98368
•
November 18, 2004 DEC 1 3 2004
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i _ f _ D A.D.A. ENGINEERING �1' !����f��N
Armstrong DeGroot&Associates,L.L.C. �,�,�!�
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P.O. Box 847 ' A
Poulsbo, WA 98370
• Phone: (360)779-6633
Bainbridge Island Phone: (206)842-6123
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Introduction
The project site is located Southwest of Port Townsend on Fager Hill Road. It is in the
NE V4 of Section 13, Township 29 N, Range 2 W, WM, Jefferson County. Access to the
site is via Fager Hill Road. This drainage report details the location and distribution of
stormwater resulting from development, and outlines the design of stormwater quality
and quantity control.
Pre-Development Condition
In the pre-developed state the lot totals 0.317 Acres. The subject lot includes sloping
terrain with established second growth timber. The drainage path for the site is
southeasterly on slopes that range up to 8.5%. Stormwater converges at the southeast
portion of the site where stormwater enters a roadway ditch(see"Downstream Analysis"
for a more detailed drainage path).
Post-Development Condition
The proposed development for the site will include developing the site for a single-family
residence. Stormwater will be collected from driveway and roof impervious areas and
transported to the catch basins sized per 2004 WSDOT Standard Specifications for Road,
Bridge, and Municipal Construction.
Theory of Analysis
The enclosed drainage computations were calculated using WaterWorks 4.13. The Santa
Barbara Urban Hydrograph method was used. The data inputs were determined per
Department of Ecology Stormwater Ordinances.
Pre-developed and post-developed areas are shown in Exhibit A. Pre-development site
conditions are established secondary growth timber. The soils analysis enclosed in this
report indicates that the soils are hydrologic group C.
Hydrograph Routing
WaterWorks 4.13 allows up to 20 hydrographs to be run. Basin ID's and their resultant
hydrograph numbers are included in the WaterWorks outputs (see Exhibit D—
Hydrological Analysis).
Conclusions
Stormwater runoff from the residence shall be tightlined to pipes located along the west
side and eastside of the residence. Stormwater runoff from driveway impervious areas
shall be collected into a catch basin. Flows from the driveway impervious areas shall
pass through an oil separator tee, which will treat flows for water quality. Flows shall be
transported in the pipes to a catch basin. From the catch basin stormwater shall be
tightlined to a level spreader where flows shall be released per Department of Ecology
Stormwater Management Design Criterion.
S
• EXHIBIT A
SITE MAPS
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SEE: FREEWIN-NELSON
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i SURVEYED1982 ( BY/82 TS )
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(VOL 7 PC. 200 ROS)
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EXHIBIT B
•
SOILS CLASSIFICATION
•
DEPARTMENT OF AGRICULTURE r• � ;
4110 CONSERVATION SERVICE
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SYMBOL NAME .1.,•
Medium Intensity ,=a
AgB Agnew silt loam,0 to 8 percent slopes _ �,„,
AgE Agnew silt loam,30 to 50 percent slopes '�n -
AhF Ahl very gravelly loam,50 to 70 percent slopes i a 'r�'•-i _
AkF Ahl-Rock outcropcomplex,50 to 90 x
P percent slopes - ;
AIC Alderwood gravelly sandy loom,0 to 15 percent slope! _
AID Alderwood gravelly sandy loam, 15 to 30 percent slopes�' � ' -
. c
AIE Alderwood gravelly sandy loam, 30 to 50 percent slopes �r,�'x -
AmC Alderwood gravelly loam,0 to 15 percent slopes
AmD Alderwood gravelly loam, 15 to 30 percent slopes p z
AuC Alderwood-Quilcene complex,0 to 15 percent slopes •-
r
BaD Beausite gravelly sandy loom, 15 to 30 percent slopes + w
BoE Beausite gravelly sandy loom,30 to 50 percent slopes T�-'"y-..... •_ -
BdD Beausite-Alderwood complex,0 to 30 percent slopes a ',% +i•.
BdE Beausite-Alderwood complex,30 to 50 percent slopes • c�`,,gi h
- J
BeE Beausite-Rock outcrop complex,0 to 50 percent slopes F'T t -
Bf Belfast fine sandy loom `` t° ' -
0 Bg Belfast silt loam � - - d
Bh Belfast silt loom,heavy variant r* x�`*
Bk Belfast silt loam,wet variant -
Bm Belfast silty clay loom,wet variant 3 N"
CaC Carlsborg gravelly loamy sand, 0 to 15 percent slopes
CoD Carlsborg gravelly loamy sand, 15 to 30 percent slopes t ,• 'k
CdB Casey fine sandy loom,0 to 8 percent slopes
CeB Casey silt loam,0 to 8 percent slopes -? vZ"c: -+
CfC Cassolory sandy loam,0 to 15 percent slopes
� 1 � � r
CfD Cassolory sandy loam, 15 to 30 percent slopes ° s r + s
CfE Cassolory sandy loom, 30 to 50 percent slopes f t w. �e4 t
ChC Cassolory-Everett complex,0 to 15 percent slopes f 1 s a y,"` * .,,a'� ;,�,,�,,,•
ChD Cassolary_Everett complex, 15 to 30 percent slopes t: .r a° `4 '� °cr‘i r
CkC Cassolory-Kitsop complex,0 to 15 pr•rront slopes ' sge;r"s 4"=� '"•-
CkD Cassolory-Kitsap complex, 15 to 30 percent slopes ti3I' °43w� � �"xf ..
CItE Cassolory-Kitsap complex,30 to 50 percent slopes +t u
CIC Cathcart gravelly silt loam,0 to 15 percent slopes i %,,?ic- �k',p f"`{ r+_
CID Cathcart gravelly silt loom, 15 to 30 percent slopes •yy,,•" to rr;r _
CIE Cathcart gravelly silt loom, 30 to 50 percent slopes *`"'�
i ._ r CmC Clallom gravelly sandy loam,0 to 15 percent slopes n,, ''tO ;r
•` tCmD - Clallom oravelly sgndv_loom, 15 to 30 percent slopes ? SSµ
Z.., ,i _ Co Coastal beaches r
. Cu Cut and fill land ) "e
' , ;Mr t DaC Dabob very gravelly sandy loam,0 to 15 percent slopes F," Z t
` DaD Dabob very gravelly sandy loam, 15 to 30 percent slopes 4 �C
'j^p DcC Dick loamy sand,0 to 15 percent slopes �a ,r ''
t EvC Everett gravelly sandy loam,0 to 15 percent slopes *A` °1
s EvD Everett gravelly sandy loam, 15 to 30 percent slopes �� Lac' s
. EvE Everett gravelly sandy loam,30 to 50 percent slopes c: ' '' r #`,rya
4 r
SK '-k'.,1.i GoC Grove very gravelly loamy sond,0 to 15 percent slopes r q
` L GoD Grove very gravelly loamy sand, 15 to 30 percent slopes k
r rf '; GoE Grove very gravelly loamy sand,30 to 50 percent slopes +c" - t
?+ �•�v. ', GrC Grove very gravelly sandy loom,0 to 15 percent slopes v r _
,�S pr`�✓k'S"►r Gr.!) Grove very gravelly sandy loam, 15 to 30 percent slopes g '
r
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III Table 2.3
Runoff Curve Numbers for Selected Agricultural, Suburban, and Urban Areas
(Sources:TR 55, 1986,andStonnwater Management Manual, 1992.See Section 2.1.1 for explanation)
CNs for hydrologic soil group
Cover type and hydrologic condition. A B C D _
Curve Numbers for Pre-Development Conditions
Pasture,grassland,or range-continuous forage for grazing:
Fair condition(ground cover 50%to 75%and not heavily grazed). 49 69 79 84
Good condition(ground cover>75%and lightly or only occasionally grazed) 39 61 74 80 _
Woods:
Fair(Woods are grazed but not burned,and some forest litter covers the soil). 36 60 73 79
Good(Woods are protected from grazing,and litter and brush adequately cover the soil). 30 55 ® 77
Curve Numbers for Post-Development Conditions
Open space(lawns,parks,golf courses,cemeteries,landscaping,etc.)
Fair condition(grass cover on 50%-75%of the area). 77 85 90 92
Good condition(grass cover on>75%of the area) 68 80 6 90
Impervious areas:
Open water bodies: lakes,wetlands,ponds etc. 100 100 100 100
Paved parking lots,roofs',driveways,etc. (excluding right-of-way) 98 98 0 98
Porous Pavers and Permeable Interlocking Concrete(assumed as 85%impervious and 15%lawn)
Fair lawn condition(weighted average CNs). 95 96 97 97
Good lawn condition(weighted average CNs). 94 95 96 97
Paved 98 98 98 98
Gravel(including right-of-way) 76 85 89 91
Dirt(including right-of-way) 72 82 87 89
Pasture,grassland,or range-continuous forage for grazing:
Poor condition(ground cover<50%or heavily grazed with no mulch). 68 79 86 89
Fair condition(ground cover 50%to 75%and not heavily grazed). 49 69 79 84
• Good condition(ground cover>75%and lightly or only occasionally grazed) 39 61 74 80
Woods:
Poor(Forest litter,small trees,and brush are destroyed by heavy grazing or regular burning). 45 66 77 83
Fair(Woods are grazed but not burned,and some forest litter covers the soil). 36 60 73 79
Good(Woods are protected from grazing,and litter and brush adequately cover the soil). 30 55 70 77
Single family residential3: Should only be used for Average Percent
Dwelling Unit/Gross Acre subdivisions>50 acres impervious area3.4
1.0 DU/GA 15 Separate curve number _
1.5 DU/GA 20 shall be selected for
2.0 DU/GA 25 _pervious&impervious
2.5 DU/GA 30 portions of the site or
3.0 DU/GA 34 basin
3.5 DU/GA 38
4.0 DU/GA 42
4.5 DU/GA 46
5.0 DU/GA 48
5.5 DU/GA 50
6.0 DU/GA 52
6.5 DU/GA 54
7.0 DU/GA 56
7.5 DU/GA 58
PUD's,condos,apartments,commercial %impervious Separate curve numbers shall
businesses,industrial areas& must be be selected for pervious and
&subdivisions<50 acres computed impervious portions of the site _
For a more detailed and complete description of land use curve numbers refer to chapter two(2)of the Soil Conservation Service's Technical
Release No.55,(210-VI-TR-55,Second Ed.,June 1986).
'Composite CN's may be computed for other combinations of open space cover type.
'-Where roof runoff and driveway runoff are infiltrated or dispersed according to the requirements in Chapter 2,the average percent impervious
area may be adjusted in accordance with the procedure described under"Flow Credit for Roof Downspout Infiltration"and"Flow Credit for Roof
Downspout Dispersion"in Chapter 2.
'Assumes roof and driveway runoff is directed into street/storm system.
• 'All the remaining pervious area(lawn)are considered to be in good condition for these curve numbers.
August 2001 Volume lii-Hydrologic Analysis and Flow Control BMPs 2-23
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IIIA-2 Volume III-Hydrologic Analysis and Flow Control BMPs August 2001
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•
A-4 Volume Ill—Hydrologic Analysis and Flow Control BMPs August 2001
11/18/04 9 : 40 : 24 am A.D.A. Engineering page 1
RICHARD BERG
11/18/04
BASIN SUMMARY
BASIN ID: PRE1 NAME : PRE DEV 6M0
SBUH METHODOLOGY
TOTAL AREA • 0. 32 Acres BASEFLOWS: 0 . 00 cfs
RAINFALL TYPE TYPE1A PERV IMP
PRECIPITATION • 1. 15 inches AREA. . : 0. 32 Acres 0. 00 Acres
TIME INTERVAL 10.00 min CN • 70. 00 0. 00
TC • 42. 72 min 0 . 00 min
ABSTRACTION COEFF: 0. 20
TcReach - Sheet L: 170. 00 ns : 0. 8000 p2yr: 1. 80 s : 0 . 0850
PEAK RATE : 0 . 00 cfs VOL: 0 . 00 Ac-ft TIME: 1320 min
BASIN ID: PRE2 NAME: PRE DEV 2YR
SBUH METHODOLOGY
TOTAL AREA • 0. 32 Acres BASEFLOWS : 0 . 00 cfs
RAINFALL TYPE • TYPE1A PERV IMP
PRECIPITATION • 1. 80 inches AREA. . : 0. 32 Acres 0 . 00 Acres
TIME INTERVAL • 10 . 00 min CN • 70 . 00 0. 00
TC • 42. 72 min 0. 00 min
ABSTRACTION COEFF: 0.20
TcReach - Sheet L: 170 . 00 ns : 0 . 8000 p2yr: 1.80 s :0. 0850
PEAK RATE : 0. 00 cfs VOL: 0 . 00 Ac-ft TIME: 960 min
BASIN ID: PRE3 NAME: PRE DEV 10YR
411 SBUH METHODOLOGY
TOTAL AREA • 0. 32 Acres BASEFLOWS: 0. 00 cfs
RAINFALL TYPE • TYPE1A PERV IMP
PRECIPITATION • 2. 00 inches AREA. . : 0. 32 Acres 0. 00 Acres
TIME INTERVAL • 10 .00 min CN • 70.00 0. 00
TC • 42 . 72 min 0. 00 min
ABSTRACTION COEFF: 0 . 20
TcReach - Sheet L: 170 . 00 ns :0. 8000 p2yr: 1.80 s : 0. 0850
PEAK RATE : 0 . 01 cfs VOL: 0 . 01 Ac-ft TIME: 960 min
BASIN ID: PRE4 NAME: PRE DEV 100YR
SBUH METHODOLOGY
TOTAL AREA • 0. 32 Acres BASEFLOWS : 0 . 00 cfs
RAINFALL TYPE • TYPE1A PERV IMP
PRECIPITATION • 3.80 inches AREA. . : 0.32 Acres 0.00 Acres
TIME INTERVAL • 10 .00 min CN • 70. 00 0. 00
TC • 42. 72 min 0. 00 min
ABSTRACTION COEFF: 0. 20
TcReach - Sheet L: 170 . 00 ns : 0 . 8000 p2yr: 1. 80 s : 0 . 0850
PEAK RATE : 0.04 cfs VOL: 0 . 03 Ac-ft TIME: 490 min
•
11/18/04 9 : 40 : 24 am A.D.A. Engineering page 3
RICHARD BERG
11/18/04
• HYDROGRAPH SUMMARY
PEAK TIME VOLUME
HYD RUNOFF OF OF Contrib
NUM RATE PEAK HYDRO Area
cfs min. cf\AcFt Acres
1 0 . 001 1320 _ 22 cf 0 . 32
2 0 .004 960 196 cf 0 . 32
3 0. 006 960 277 cf 0 . 32
4 0 . 036 490 1379 cf 0 . 32
5 0. 023 480 489 cf 0.32
6 0. 056 480 1032 cf 0 . 32
7 0 . 067 480 1215 cf 0. 32
8 0. 180 480 3032 cf 0. 32
•
• Upstream Summary
Stormwater from neighboring properties flows away from the subject property. This is
evident by the topography map on the following page.
Downstream Summary
Flows from the subject property flow into the existing ditch along Freeman Lane. Once
into the ditch stormwater is conveyed southerly until it crosses the road towards the east.
From this point flows follow natural sloping terrain and disperse into the natural ravine.
Please refer to the following page for more detail.
Sediment and Erosion Control
During the construction phase it may be possible that Erosion could occur resulting in the
transportation and deposit of sediments. This shall be prevented by conducting
construction during the summer months when rain fall is less likely, installing silt fencing
around the down gradient boundaries, spreading straw over disturbed areas that
construction has concluded in, and finally reseeding all disturbed areas. If these
measures are installed and properly maintained, sedimentation and erosion will be
• eradicated.
• EXHIBIT F
CALCULATIONS
•
•
. .
�
A.D.A. ENGINEERING, L.L.C.
Engineering & Surveying SHEET NO. or -
Lindvig Way P.O. Box 847
WV\ 9837O CALCULATED BY . o^rs
(360) 779-6633 ( ��� l23
FAX (360) 779_7031 oweono,o, DATE
� SCALE �
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• 02/09/2005 15:59 3604528498 NTI JLS GROUP PAGE 02
NORTHWESTERN TERRITORIES, INC.
A JLS GROUP COMPANY
• 717 SOUTH PEABObY STREET,PORT ANGELES,WA 98382
0 Engineers 0 Land Surveyors 0 Geologists •
NTIO Construction Inspection o Materials Testing
(380)45243491 FAX 452-8490 www.ntiau,com E•Mall:infoent14u,com
JLS GROUP,
INC. '
February 9, 2005
Jefferson County Department of Community Development
Attn: Fred Slota
Re: Dan O'Donnell Project
Dear Fred:
Per our phone conversation today, it is OK for Mr. O'Donnell to begin construction on
the retaining wall at this time. If unsuitable soil is encountered as mentioned in
recommendation #4 of the geotechnical report, the soil should be over excavated down
to firm unyielding soil and replaced.with suitable structural fill placed in --8" lifts and
compacted to 95% of the modified proctor value.
If you have any further questions regarding this matter,
9 9 , please feel free to call us.
Sincerely,
NORTHWESTERN TERRITORIES, INC. (jai
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Bill Payton, L.F.G. ;�,
Engineering Geologist �`� .
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• FEB r 9. 2005