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Technical Information Report
Enebrad
Short Plat
357 Lind Avenue NW
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Prepared: February 5, 2003
DCI Project: 02968
Duncanson Company, Inc.
1445W 155`�Street,Suite 201
Seattle,Washington 98166 DEVELOPMENT PLANNING
(2(�244-4141 � C�TY OF RENTON
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02968-Enebrad Short Plat 02/OS/03
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Table Of Contents
Project Overview
Technical Information Report Worksheet
Preliminary Conditions Summary
Off-Site Analysis
Off-Site Analysis Drainage System Table
Figure I.1- SCS Soil Survey Map
Figure III.1-Off-Site Analysis Map
Figure III.2-Assessors Map
Figure III.3- Wetland
Figure III.4- Stream Map
Figure III.S-Erosion Hazard Map -
Figure III.6- Landslide Hazard Map
Figure III.7- Seismic Hazard Map
Figure III.B- Basin Map �
Fib re III.9-Drainage complaints
Retention/Detention Analysis and Design
Figure IV.l Predeveloped Conditions
� Figure IV.3 Postdeveloped Conditions
Postdeveloped Calculations
Conveyance Systems Analysis and Design
Special Reports and Studies ,
Other Permits
ESC Analysis and Design
Bond Quantities VVorksheet
�
I. Project Overview �
02968-Enebrad Short Plat 02/OS/03
1
Page 1 of 2
King County Building and Land De�elopment Division
� TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
- . . � - . . .
. s � � •
Project Owner y» �,�i ES�A.� Project Name c�✓C �2iP
Address 8��. � � . � � �F- !n 5T. Location
Phone 20�� — ?'7 2-' �'5��� Township 2 �_
Project Engineer �dyb(� �L S�ti� Range 0 S�
Section ! -�._
Company�a.t���� �� � ���.�. Project Size o, �3 AC
Address Phone L��' S l�! /5��. #/0 2 Upstream Drainage Basin Size �.4�3AC
��4rrr� �Y-�lG�,;��...—Z�Sf �/ S//
• • o
C Subdivision � DOF/G HPA 0 Shoreline Management
[� Short Subdivision 0 COE 404 � Rockery
0 Grading � DOE Dam Safety � Structural Vaults
� Commercial 0 FEMA Floodplain � Other
Cj Other � COE Wetlands 0 HPA
. �� � �
' Corr�unity
�
I ,�,Tf�i�!'T"v/lf
Drainage Basin
L c.►�� �4 s�-1�tiLC�'��.l
-� ..
; i River �J Floodplain
O Stream � Wetlands
0 Critical Stream Reach 0 Seeps/Springs
� Depressions/Swales � High Groundwater Table
� Lake 0 Groundwater Recharge
0 Steep Slopes 0 Other '
0 Lakeside/Erosion Hazard
I,
•�
I
Soil Tvpe Slopes Erosion Potential Erosive Velocities i
G io - ��/ �Y1m n��.�v-rE �/.�
I � Additional Sheets Attatched
1/90
Page 2 of 2
King County Building and Land Development Division
� TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
� , . � ..
I REFERENCE LIMITATION/SITE CONSTRAINT
� Ch.4-Downstream Analysis �1../��lE"
a
a
0
a
a
' ,�1 Additional Sheets Attatched
�
i MINIMUM ESC REC�UIREMENTS MINIMUM ESC REC�UIREMENTS j
DURING CONSTRUCTION FOLLOWING CONSTRUCTION i
I � 0 Sedimentation Facilities �l Stabili�e Exposed Surface '
I� Stabilized Construction Entrance [� Remove and Restore Temporary ESC Facilities
[�] Perimeter Runoff Control 0 Clean and Remove All Silt and Debris ,
� Clearing and Grading Restrictions � Ensure Operation of Permanent Facilities
� Cover Practices � Flag Limits of NGPES
� Construction Sequence � Other
� Other
�
i
' � Grass Lined Channel 0 Tank C Infiltration Method of Analysis
� Pipe System 0 Vault � Depression
[�] Open Channel � Energy Dissapator � Flow Dispersal Compensation/Mitigation
� Dry Pond � Wetland � Waiver of Eliminated Site Storage
� Wet Pond 0 Stream � Regional Detention
Brief Description of System Operation /l!o ��T.Qii�TL/��� ��_�s���_
Facility Related Site Limitations � Additional Sheets Attatched
Reference Facility Limitation
l
. � �, _ �
C Drainage Easement �
Ci Cast in Place Vault I� Other � Access Easement �I
[� Retaining Wall 0 Native Growth Protection Easement �
C� Rockery>4'High 0 Tract
� Structural on Steep Slope ! � Other I
�
• - � •
I or a civil engineer under my supervision have visited the site. Actual
site conditions as observed were incorporated into this worksheet and the �
attatchments. To the best of my knowledge the information provided ' �
here is accurate. s;�,Kav.r�
1/90
.
I. Project Overview
The proposed 357 Lind Avenue NW site involves the short platting a 0.33-Acre single-
family parcel into three new lots. Single family residences adjoin the site to the north, south
and west.
The existing site contains an exisring house and gravel drive/parking area. The remainder of
the site consists of�ass and a few trees. The soil is a brown sandy loam to a depth of five to
six feet then weathered bedrock. No indications of saturated soil were observed above five
feet. This is consistent with the King County Soil Survey map, Figure I.1. The Site slopes
to the east at approximately 20%. A few low rockeries (less than two feet) provide teiracing.
Runoff flows off the Site's east boundary as sheet flow onto Lind Avenue. Refer to the off-
site analysis for a complete description of the storm drain systems.
02968-Enebrad Short Plat 02/OS/03
2
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DUNCANSON COMPANY, INC.
Ci��l Engineering � Sun�eying � I.and Planning
- - � 145 S[�'1 SSth STREET,102
, Seattle, Washington 98166
� Phone 206.244.4141
-' Nax 206.244.4455
Figure I.l Soil Survey Map
Scale:N/A Drawn: ��,'� r�h tr,. ���Fe
I 3
II. Preliminary Condition Summary
02968-Enebrad Short Plat 02/05/03 II
�
II. Preliminary Conditions Sumrnary
T'he Proposed Enebrad Short Plat includes the subdivision of 0.33 acres of developed
land into three single family residential building lots. The Site is located in the Lake
Washington Basin northeast of Lind Avenue NW and vacated NW 3`� Place intersection.
The Site is cunendy developed with a 1,670 square foot single family home which is
intended to remain. A portion of the �arage will be removed to meet building setbacks.
The e�sting surface conditions are shown and tabulated on Fig. 3
The project will require street improvements and these offsite new unpervious areas are
included in the hydrologic analysis. The improvements will be designed to 1990 King
County Surface Water Manual standards. The total project area is 0.43 Acres. With less
than 0.1 CFS increase in post-developed runoff for the 100-year storm, no flow control
improvement are proposed.
The net increase of 0.06 CFS for the 10, 25 and 100-year storm event will not have an
adverse impact on downstream conveyance. A downstream analysis of the conveyance
system with such a small increase in runoff is limited to an inspection of the facilities for
existing problem.
With less than one acre of new impervious surface, no water qualiry faciliry is proposed.
�
02968-Enebrad Short Plat 02/OS/03
5
III. Offsite Analysis
02968-Enebrad Shon Plat 02/OS/03
�
III. Off-Site �nalvsis
Task 1 - Study Area De�nition & �Iaps
The Site and more detailed mapping of the downstream draina�e components are shown
on Figure III.1 - Off-Site Analysis Map. This off-site analysis investigates the condition
of the downstream runoff conveyance system as prescribed by the 1990 King County
Surface Water Design Manual.
Task 2 - Resource Review
This section discusses applicable findings from a review of available resources.
1. Basin Reconnaissance Sunzmcary Reports and Maps
The applicable pages of the Basin Reconnaissance Summary Report are included as
Figures III.8. -
2. Critical Drainage Area Maps
No critical drainage area requirements apply to this Site.
3. FEMA M�ps
FEMA Map indicates no flood plain in or around the Site. The FEMA Map is not
included.
4. Otlzer Off=Site Analysis
No other off-site analyses have been reviewed.
5. Sensitive Area Maps
The sensitive area maps showing the Site are included as Figures III.3, III.4, III.�,
III.6, and III.7.
6. SWM Division Drainage Investigntion Section Problem�Ylaps
The King County Drainage Investigation Unit provided a list of reported complaints
based on an address search around the Si�e
7. USDA-SCS Soil Survey Ma��s
The SCS Soil Survey Map. Fi�,ur� l.l, indicates u :�l�i�iti����o� S�il T.�p� that
classified as Hydrologic Group C. No drainage problems were identified in the soi'�
survey.
8. Wetland Inventory Maps
This site is not located upstream from any wetlands according to the King County
Wetland Inventory Maps.
02968-Enebrad Short Plat 02/OS/03
7
� Task 3 - Field Reconnaissance
A field reconnaissance was conducted on December 13, 2002. Weather conditions were
moderate rain with heavy rain the previous two days. The downstream conveyance
system was followed from the Site to a point over 1/4 downstream.
Task 4 - Drainage System Description And Problem Screening
Component A — Sheet Flow across Lind Ave. NW(0—60')
Runoff sheet flows off the property's east boundary, across Lind Avenue NW to a
thickened pavement edge. Runoff collects along this curb line and flows north at
approximately 5% until parallel to the property's northeast corner.
Component B— Open Channel Flow (60'—2I0')
Runoff continues along the Lind Avenue east thickened edge curb line for 150 feet at
a slope of approximately 10%. The flow line turns east at NW 4�' Street.
Component C—Open Channel Flow (2I0'—410')
Runoff continues east in a thickened edge curb, along the south edge of NW 4�'
Street, for 200 feet and at a slope of approximately 15%.
Component D— Catch Basin (410')
The runoff discharges into a Type 1 Catch Basin at the southwest corner of the NW
4�'Street and Maple Avenue NW. The catch basin discharges east.
Component E—I2"Pipe Flow (4I0'— 690') '
Runoff from Component D outfalls to a 12" concrete pipe flowing east 280 feet with
1 SIO� CSt1ITlai��j �'1T ���'� -('}l� niri� ��ic�l;�il•�-;� i�� 1 T��j��' TT ���T�h T�l� ;��'_h h.i�i�,
discharges eas�
Component F— Catcja Basin (690')
Runoff from Component E out falls into a Ty�pe II Catch Basin at the southwest
corner of the intersection of NW 4�` Street and Taylor Avenue NW. Runoff enters
from the west and discharges to the south.
Component G—Pipe Flow (690'-7I0')
Runoff from Component E outfalls to a 12" concrete pipe flowing south 20 feet to a
Type I catch basin.
Component H— Catch Basin (710')
Runoff from Component G discharges to a Type I Catch Basin located on the west
edge of pavement of Taylor Avenue NW. Runoff enters from the north and
discharges to the south.
Component I- Pipe Flow (7I0'-770')
02968-Enebrad Short Plat OJOS/Q3
�
.
� Runoff outfalls from Component H to a 12" concrete pipe flowing south 60 feet to
component J.
Component J— Catch Basin (770')
Runoff from Component I discharges to a Type I Catch Basin located on the west
ed�e of pavement of Taylor Avenue NW. Runoff enters from the north and
discharjes to the south.
Component K-Pipe Flow (770'-810')
Runoff outfalls from Component J to a 12" concrete pipe flowing east 40 feet under
Taylor Avenue to component L.
Component L— Catch Basin (8l0')
Runoff from Component K discharges to a Type I**�`Catch Basin located on the west
edge of pavement of Taylor Avenue NW. Runoff enters from the north and
discharges to the south.
Component M-Pipe Flow (810'-IIIS')
Runoff outfalls from Component K to a 12" concrete pipe flowing south 305 feet to
component N.
Component N— Catch Basin (IIIS')
Runoff from Component M dischazges to a Type I�`�"` Catch Basin located on the
east edge of Taylor Avenue NW and the center of NW 3`d Place. Runoff enters from
the north and discharges to the east.
Component O- Pipe Flow (1115'-1375') ,
Runoff outfalls from Component N to a 12" concrete pipe flowing east 260 feet to
component N.
This completes the one-quarter mile downstream analysis. According to Renton
Public Works records, this pipe flow continues east to the W Perimeter Road
conveyance system flowing north.
Task 5 - Conclusion I'!
There were no observed problems in any of the off-site components. Project I
Development is anticipated to create negligible impact in the study area.
02968-Enebrad Short Plat 02/OS/03
9
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Q o /�
Z 0�93 2 � 2 Go N �/ w 6 q0�3p J� CivilEngineering • Surveying • LandPlanning
�'��_' p ^ Z�� Z � 200 �40 1 P °� � 145 S6V ISSth Street Suite 102
� Q � m v ��� Seattle, Washington98166
�..�[.�7E0 �: -ii-i945 � � ,� W v�c. � oRo• 324G ,� � Nw Phone 106.144.4141
m � m �Ac. oRo. 4259 �
c aRa.� ��.�- u �'—� W — — �a� Fax 206.149.4455
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Figure III.1 -OFFSITE ANALYSIS I
Scale: 1"=100' Drawn: WO Job No. 02968
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DUNCANSON COMPANY, INC.
, Civil Enginoering � Survtying - I.and Plauning
! 145 SW ISSth STREET, 102
I
� Seattle, Wasbington 98166
/ Phone 106.244.4141
� �� Fax 206.244.4455
Figure III3 Wet(and Map
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DUNCANSON COMPANY, INC.
Civil Engineering Sun•eying • Land Planning
- - � I45 SW ISSth S7REET, 101
i Seattle, Rjashingion 98166
� Phone 206144.4I41
- � haz ?06.244.4455
Figure III.4 Stream Map
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DUNCANSON COMPANY, INC.
Civil Engineering Sun•eying - Iand Plaming
l45 Sf3'I SSth STREET, 102
i � Seattle, Washington 98166
�� Phone ?06.244.4141
Fax ?06.?44.44�5
Figure III.6 Landslide Hazard Map
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DUNCANSON COMPANY, INC. '
i Civil Engiaeering Surveyiog - Land Plaming
— — � l45 SiV ISSth STREET,101
Seadle. Washington 981 G6
�� Phone Z06.Z44.4141
- �' Fax Z06.244.4455
Figure III.7 Seismic Hazard Map
Scale:N/A Drawn:WO Job No.02968
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DUNCANSON COMPANY, INC.
Civil Engineering � Swveying - Land Planning
j /45 SI�'155th STREET, l02
� Seattle. Washington 98166
Phone 2�6.144.4141
� "� Fax 206.249.44�5
Figure III.8 Basiu Map
Scale:N/A Drawn: WO Job No. 02968
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IV. Retention/Detention Analysis and
Design
02968-Enebrad Short Plat 02/05/03
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ASPHALT 5A0 SF
TOTAL B�APERVIOUS 4,760 SF (OJ09 Ac)
TOTAL PEVIOUS AREA 14,155 SF(0.325 Ac)
DUNCANSON COMPANY, INC.
EX�1�.7 ���M\ Civil Engiueering • Surveying • Land Planuing
�fV1� a7V1l�A�� Seatt� �hingt�98 662
Phone 206.Z44.4141
GRAVEL DFlIVEWAY �,�rJ � Far 206.244.4455
CONCHETE DRNEWAY 285 SF
ASPHALT ROAD �p � Figure IV.1 EJcisting Site Conditions
TOTAL PGS 2,310 SF Scale: 1"=30' Drawn:WO Job No. 02968
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RETAINING WALL, STRUCTUAL 20' THICKENED EDGE ASP
DESIGN BY OTHER TAPER
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STA�+50.00 BEGIN SIDEWALK
Se8'+r,'ta'E ;oo.oc' CURB & GUTTER
�1�k ADJUST RIM TO FINAL GRADE
PtR ORDINAN�NSo T2tos�Q�O��RETAINING WALL, STRUCTUAL
��ryo DESIGN BY OTHER I 5' CONCRETE TRANSITION RAA
30.00' 35' THICKENED EDGE ASPHAL
GRAPHIC SCAI.E TAPER
PROP'OSED 3�TE COND�TIONS
TOTAL AREA OF 14,565 ACF�S
WITFi 9 DU/ACRE, ASSUME 60% IMPB3VIOUS AREA
TOTAL IMPB�VIOUS - 0.60 X 14,565-11,350 SF
TOTAL PEVIOU.S AREA �,� - tI,3JO ' 7,J�O SF D U N C A N S 0 N C 0 M P A N Y, I N C.
i Civil Eogineering • Surveying • Iaod Plaming
�W �L�� - - /45 SW ISSth STREET, 102
^�,��w �y ,p� i I Seattle, Washington 98166
�I�Gf7lY� �7Vflf�'A�S / Phone 106.244.4141
- � Faz 206.144.4455
ASPHLT DRNEWAY 2,675 SF
ASPHALT ROAD 2,Q15 SF Figure N.2 Developed Site Conditions
TOTAL PGS 4,680 SF Scale: 1"=30' Drawn:WO Job No. 02968
/9'
� IV.Retention/Detention Analysis and Design
Part A—E�sting Hvdrolo�y
The Site includes one subbasin defined by topo�aphical relief. Overall relief across the
property slope east at an average of 20%. Site runoff flows east in an overland fashion.
Runoff flows across the east boundary of the property onto and across Lind Avenue NW.
Refer to the off-site analysis for a complete description of the offsite storm drain systems to
� the Lake Washington Basin
A small "run-on"basin(12,500 SF±)exists between the Site's eastern property and Stevens
Avenue NW. This area is developed residential property. Runoff from this area appears to
flow through the Site as sheet flow and will not be altered. This offsite runoff will be
addressed in the downstream conveyance analysis
F'igure IV.1 -Predeveloped Conditions show the approximate basin delineation.
For identification purposes Basin ,Ex�cx, refers to Existing Site condirions and the
associated storm event (year x�c). Runoff from this Basin sheet flows to the east
boundary of the Site. The Site azea includes the short plat property and the area between
the property's east boundary and the centerline of Lind Avenue NW, 0.43 Acres.
Hydrologic parameters and peak runoff rates are summarized on the Basin Summary
sheets below. Detailed area calculations are included on the following pages.
Pre-develo ed conditions: 'I
Impervious area:
gravel drive: 1,430 SF
buildings: 1,670 SF
concrete: 1,070 SF
asphalt: 570 SF
Total: 4.760 SF �
Pervious area:
Till Grass: 14,155 SF
Water Works Input Parameters
Pre-developed Land Cover SF Acres
Impervious 4,760 0.109
Grass (Till) 14,155 0.325
Time of Concentration 7.13 Min.
02968-Enebrad Short Plat 02/OS/03
2G
Part B -Developed Site Hvdrology
For identification purposes Basin, D�cx, refers to Developed Site conditions and the
associated storm event (year�x). Runoff from this Basin sheet flows to the east boundary
of the Site. The Site area includes the short plat property and the azea between the
property's east boundary and the centerline of Lind Avenue NW, 0.43 Acres. Hydrolob c
parameters and peak runoff rates are summarized on the Basin Summary sheets below.
Detailed area calculations are included on the following pages.
Post-developed conditions:
Impervious area:
Estimated at 60% w/9 du/acre 11,350 SF
Pervious area:
Remaining grass: 18,915 - 11,350 7,570 SF
Water Works Input Parameters
� Post-developed Land Cover SF Acres
Impervious 11,350 0.260
Grass 6,325 0.174
Time of Concentration 6.39 Min.
Part C -Hvdrolo 'i�lvsis
Hydrologic analysis of the Site was conducted with the Water Works software in accordance I
with 1990 KCSWDM. Pre-developed and Post-developed runoff peak values are tabulated
below. �
Basin, Event Year Peak Runoff
Existin , 10- ear 0.14 CFS
Existin , 25- ear 0.18 CFS ,
Existin , 100- ear 0.22 CFS
Develo ed, 10- ear 0.20 CFS
Develo ed, 25- ear 0.24 CFS
Develo ed, 100- ear 0.28 CFS
02968-Enebrad Short Plat 02/OS/03
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« 12/29/02 Duncanson Company Incorporated page 1
Enebrad Short Plat
BASIN SUMMARY
BASIN ID : DO10 NAME : Developed 10-yr event
SBUH METHODOLOGY
TOTAL AREA. . . . . . . : Q .43 Acres BASEFLOWS : 0 . 00 cfs
RAINFALL TYPE . . . . : TYPElA PERVIOUS AREA
PRECIPITATION. . . . : 2 . 90 inches AREA. . : 0 . 17 Acres
TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 50 . 00
TIME OF CONC. . . . . : 6 . 39 min IMPERVIOUS AREA
ABSTRACTION COEFF : 0 . 20 AREA. . : 0 . 26 Acres
CN. . . . . 98 . 00
PEAK RATE : 0 . 20 cfs VOL: 0 . 07 Ac-ft TIME : 480 min
BASIN ID : D025 NAME : Developed 25-yr event
SBUH METHODOLOGY
TOTAL AREA. . . . . . . : 0 .43 Acres BASEFLOWS : 0 . 00 cfs
RAINFALL TYPE . . . . : TYPElA PERVIOUS AREA
PRECIPITATION. . . . : 3 . 40 inches AREA. . : 0 . 17 Acres
TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 80 . 00
TIME OF CONC. . . . . : 6 . 39 min IMPERVIOUS AREA
ABSTRACTION CaEFF : 0 . 20 AREA. . : 0 . 26 Acres
, CN. . . . . 98 . 00
PEAK RATE : 0 . 24 cfs VOL: 0 . 09 Ac-ft TIME : 480 min
BASIN ID : D100 NAME : Developed 100yr
SBUH METHODOLOGY
^'OTAL AREA. . . . . . . : 0 .43 Acres BASEFLOWS : 0 . 00 cfs
RAINFALL TYPE . . . . : TYPElA PERVIOUS AREA
PRECIPITATION. . . . : 3 . 90 inches AREA. . : 0 . 17 Acres
TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 80 . 00
TIME OF CONC. . . . . : 6 . 39 min IMPERVIOUS AREA ,
ABSTRACTION COErF : 0 . 20 AREA. . : 0 . 26 Acres
CN. . . . : 95 . 00
PEAK RATE : 0 . 28 cfs VOL : 0 . 11 Ac-ft TIME : 480 min
�2
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12/29/02 Duncanson Company Incorporated page 2
- Enebrad Short Plat
BASIN SUMMARY
BASIN ID: E010 NAME: Existing 10-yr event
SBUH METHODOLOGY
TOTAL AREA. . . . . . . : 0 .43 Acres BASEFLOWS : 0 . 00 cfs
RAINFALL TYPE . . . . : TYPElA PERVIOUS AREA
PRECIPITATION. . . . : 2 . 90 inches AREA. . : 0 . 33 Acres
TIME INTERVAL . . . . : 10 . 00 min CN. . . . : 80 . 00
TIME OF CONC. . . . . : 7 . 13 min IMPERVIOUS AREA
ABSTRACTION COEFF: 0 . 20 AREA. . : 0 . 11 Acres
CN. . . . . 98 . 00
PEAK RATE : 0 . 14 cfs VOL: 0 . 06 Ac-ft TIME : 480 min
BASIN ID : E025 NAME : existing 25-yr storm event
SBUH METHODOLOGY
TOTAL AREA. . . . . . . : 0 . 43 Acres BASEFLOWS : 0 . 00 cfs
RAINFALL TYPE. . . . : TYPElA PERVIOUS AREA
PRECIPITATION. . . . : 3 .40 inches AREA. . : 0 . 33 Acres
TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 80 . 00
TIME OF CONC. . . . . : 7 . 13 min IMPERVIOUS AREA
ABSTRAC'�ION COEFF: 0 . 20 AREA. . : 0 . 11 Acres ,
CN. . . . . 98 . 00
FEAK RATE : 0 . 18 cfs VOL : C . C�7 Ac-�t '?'TME : 480 mi�
BASIN ID: E100 NAME: Existing 100yr
SBUH METHODOLOGY
TOTAL AREA. . . . . . . : 0 .43 Acres BASEFLOWS : 0 . 00 cfs
RAINFALL TYPE . . . . : TYPElA PERVIOUS AREA
PRECIPITATION. . . . : 3 . 90 inches AREA. . : 0 . 33 Acres
TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 80 . 00
TIME OF CONC. . . . . : 7 . 13 min IMPERVIOUS AREA
ABSTRACTION COEFF: 0 . 20 AREA. . : 0 . 11 Acres
CN. . . . . 98 . 00
PEAK RATE: 0 . 22 cfs VOL: 0 . 09 Ac-ft TIME : 480 min
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Part D - Retention/Detention Svstem
Curiously, the net increase for each of the three storm events is 0.06. With less than a
0.5 CFS increase in runoff for the 100-year event, control is not required for this basin
according to KCSWDM Core Requirement#3: Negligible Peak Runoff Rate Increase '
Exemption. I
Part E—Water Qualitv Svstem
The existing pollution �eneratin� surface area is 2,310 SF and the developed conditions
propose 4,680 SF of PGS. This will result in an increase of 2,370 SF of new PGS. With less
than 5,000 SF of new PGS, the project is below the threshold requiring a water quality
structure, per Sec. 1.2.3 of 1990 KCSM. No water qualiry facility is proposed.
02968-Enebrad Short Plat 02/OS/03
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V. Conveyance System Analysis and
Design
�
02968-Enebrad Short Plat 02/OS/03
2.5
V. Conveyance System Analysis and Design
The Site currently discharges offsite east as sheet flow across Lind Avenue NW to the
thickened edge asphalt pavement. This channel conveys the site's and the small area
adjacent to the site (approx. 16,SQ0 SF) runoff north to the intersection of Lind and NW 4�'
Sireet. The runoff then turns east and flows to a catch basin at the southwest comer of the
Maple Ave. NW and NW 4`'' Street intersection. The area direcdy south of the site flows
south and the azea east of the site discharge east. The only area contriburing to the site's
conveyance channel is the site, approximately 12,000 SF of area west of the site and a
portion of the Lind Ave. ROW, approximately 4,500 SF.
A catch basin at the center and west edge of the Lind Ave and NW 4�' St. intersection picks
up the majority of the offsite runoff between the site and NW 4`'' St. intersection. This
intemediate runoff is conveyed to the catch basin in the�Maple and 4�' Street intersection via
12-inch concrete pipe.
No evidence of conveyance problems was found in our course of investigation. With the
increase of 0.06 CFS for the 100-year storm due to development, no significant increase in
conveyance capacity will be required.
,
02968-Enebrad Short Plat 02/05/03
2�o
VI. Special Reports and Studies
. �
02968-Enebrad Short Plat 02/OS/03
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vII. Basin and Community Plan Areas
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VII. Basin and Community Plan Areas
N/A
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VIII. Other Permits
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VIII. Other Permits
N/A
3l
IX.
Temporary Erosion and Sediment
Control Analysis and Design
,
02968-Enebrad Short Plat 02/OS/03
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IX. Temporary Erosion and Sedunent Control Analysis and Design
With the small area to be developed, 0.33 Acres, temporary erosion and sediment control
is provided with a silt fence located on all downslope boundaries. A construction
entrance is proposed to prevent the transport of sediment offsite.
02968-Enebrad Short Plat 02/05/03
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X. Bond Quantities
,
02968-Enebrad Short Plat 02/OS/03
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a
♦ ,.
X. Bond Quantities
N/A, no detention/retention facilities proposed.
02968-Enebrad Short Plat 02/OS/03
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♦ `
XI. Maintenance Manual
02968 -Enebrad Short Plat OZ/05/03
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XI. Maintenance Manual
N/A, no permanent structures proposed.
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