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� �h CONCEPT ENGINEERING, INC.
� Q 455 Rainier Boulevard North�`�f -� ..��'
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� �r � Issaquah,Washington 98027
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BREMERTON TOWNHOMES
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TECH1vICAL INFORMATION REPORT
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� Applicant:
_ Isola Homes LLC
� 555 South Renton Village Place
� Renton WA 98057
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Barry R. Constant,P.E.
� Job No.31125
January 2013
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CIVIL ENGINEERINGi SURVE"IVG;'LA�'D JSE PI�Nf�WG
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Bremerton Townhomes January 2013
ITechnical Information Report
TABLE OF CONTENTS
� TABLE OF CONTENTS...........................................................................I �
LIST OF FIGURES.................................................................................I
I. PROJECT OVERVIEW............................................................................1
II. CONDITIONS &REQUIlZEMENTS SUMMARY............................................6
III. OFFSITE ANALYSIS..............................................................................8
� N. FLOW CONTROL & WATER QUALITY ANALYSIS::::::::::::::::::::::::::::.:..:..:.12
A. Existing Site Hydrology.. .12
B. Developed Site Hydrology...................................................................12
-� C. Performance Standards........................................................................14
D. Flow Control System.. .14
E. Water Quality System.........................................................................15
� V. CONVEYANCE SYSTEMS ANALYSIS AND DESIGN..................................15
� VL SPECIAL REPORTS AND STUDIES.........................................................15
� VII. OTHER PERMI'I'5.................................................................................15
� VIII. CSWPPP ANALYSIS AND DESIGN..........................................................16
� IX. BOND QUANTITIES, FACILITIES SL�`�I:MARIES &DECLARATION OF
COVENANT.......................................................................................16
� X. MAINTENANCE AND OPERATIONS MANUAL..........................................16
i
� LIST OF FIGURES
jFigure 1 - Lake V�'ashington % Cedar River w'atershed........................................3
Figure 2-iMap Aerial Photograph of project site.............................................4
Figure 3 -Project Site Map........................................................................5
Figure 4-Downstream Drainage Map.........................................................11
Figure 5 -King County Precipitation Map.....................................................13
APPENDICES
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; Appendix A-KCTRS Runoff Calculations...................................................17
Appendix B -KCBW Backwater Runoff Calculations.......................................
Appendix C-Storm Water Pollution Prevention Plan.......................................26
� SWPPP Appendix A-F
Appendix D-Geotechnical Report..............................................................67
Appendix E-Drainage Complaint Results....................................................99
Appendix F-Bond Quantity Form........................................................... 101
�
P�r �] ]25 :eneineering i...r' word!TIR:�Final-Re�ised TIR ]0-26-201?.doc
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I
• Bremerton Townhomes January 2013
Technical Information Reporf
I. PROJECT OVERVIEW
� The proposed Bremerton Ave Townhome Plat is 26 lot ingle family attached residential
subdivision situated on 2 existing lots with a total area of�1.84 acr (see Figure 1, Site Plan). It
I `
is located at 320 and 330 Bremerton Ave NE; on the east sides of Bremerton Ave approximately
I 300' south of NE 4th St, TPs 152305-9193 and—9035.
�
The project was granted preliminary plat approval in 2006 (LUA06-133) and on March 26,
� 2007 the Conditional Use Permit (CUP), SEPA Environmental Review and the Site Plan
, Review were approved for the subject parcels. Both the original CUP and Site Plan Review
Ihave expired, but a reapplication of the project to the City of Renton on February 9, 2012 and _
I detenl]]nP,(�t(l hP ['-L11Y11'1�PtP �n FPhn�arv 16 2012 resulted in the annrov�n_fthP Ariminicrrat;.,P
Site Plan and the Conditional Use Permit on May 21, 2012 (LUA12-008).
Due to the Washington States Vested Rights Doctrine, RCW 58.17.033, development standards
, in place at the time of the Preliminary Plat was determined to be complete, would be the
development standards applicable to the subject Preliminary Plat. LUA06-133 was determined
� to be a complete application on October 27, 2006. The standards used to design this Plat are the
King County Storm Water Design Manua12009 version and the City of Renton standards at the
time.
According to the KCSWDM, this project is required to provide a Level 2 do���nstream
protection to the surrounding area, which includes adding Flow Control BMP's to the drainage
design. Following the flow chart for BMP lot requirements, this project has 58.7%o impervious
i
large lot requirements as shown in the lower left hand corner. According to this requirement,
this site will provide the lesser of the two standards; 20% site impervious area(9,409 s� or 40%
of target impervious surface (18,817 s�. We will provide the 9409 sf of item number 5 in the
� list, permeable paving, on access driveways inside the pla see A endix G r table indicating
I
separate permeable paving area square footage (with the total) and an Exhibit Map.
P:/31125 /engineering!...l word/TIR!Final-Revised TIR 10-26-2012.doc
. �
� Bremerton Townhomes January 2013
Technical Information Report
The site is zoned CA and is within the NE 4`h St Corridor Business District. The proposed
product will be attached townhomes with a mixture of 2 and 3 unit buildings. Each unit w�ill
have its own lot. Sunounding properties to the north, east and west are similarly zoned CA, the
property to the south of the Triplex buildings is zoned R-8. The site currently has 2 existing
residences. Both houses and all garages/sheds will be removed. Both houses have driveways
connected to Bremerton Ave NE. Recent residential construction borders the site on the �vest
(plat of Ridgeview Court), east(Hillcrest Village Condominiums) and south (plat of
Laurelhurst). A US Bank corporate outlet is adjacent to the north.
Proposed use of the property as a 26 lot attached townhome residential subdivision that will be
� consistent with surrounding development. Proposed lots will range in size from the minimum of
1535 sq. ft to a maximum of 4596 sq. ft (including access and drainage easements). Density of
the plat is 20.0 units per acre. Access to the new lots will be from a new internal public street
that runs east/west and is connected to Bremerton Ave NE. Within the plat, the public road
forms a modified hammerhead with a short leg to the north and a longer leg to the south, leading
to a short private road extension to serve the southerly 4 lots.
The public street is to be 32' wide within a 42' right-of-way. Thc reduced ROW w�ill be wide
enough to accommodate the street and sidewalks on both sides. The reduced ROW width was
originally needed to keep the net lot area at a maximum to stay under maximum density,
although density requirements may have since relaxed. Three joint use driveways and four
private alleys, all in easements, will be used to access most of the two unit buildings.
r'
Ridgeview Court subdivision has improved Bremerton Ave NE on the west side but not on the
� east side. This proposed plat would construct the east side of the street to complete the full road
section. New water and sewer mains will be installed in the plat street and will connect to
.��` existing mains in Bremerton Ave NE. The water main will run through the site and connect to a
� water main stub in the Hillcrest Condos. The City of Renton provides water and sewer service.
� This drainage basin is known as the Lower Cedar River drainage basin with all surface waters
eventually entering Lake Washington near the southern end of the lake. Stormwater will be
collected in a catch basin system, located in the public and private streets, and collected in an
P:�31125 ensineerine ��...� word � TIR�� Final-Re��ised TIR 10-�6-201?.doc
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Bremerton Townhomes January 2013
� Technical information Reporf
underground vault located near the northern property line. Drainage will discharge at the
� northeast corner of the site into an existing 12" stub provided by the Hillcrest Condominiums to
the east.
I
As part of the second review comments, from the City of Renton, an investigation was
jconducted by Concept Engineering,Inc. regarding the outlet pipeline. It was discovered
that the outlet pipeline was installed from the westside of the Hillcrest Village
I
� Condominiums property to the east property line of the site. And no further than that.
We performed a television inspection of the pipeline to the east from an existing manhole
� (as shown on the original site drawings) and discovered that the pipe was stubbed to the
property line and capped. Essentially, there is no outlet for this pipeline or for the current
� project, but this pipe will be installed during coostruction of the plat infrastructure.
Further inquiries to the original contractor and supervisor of the Hillcrest Village
� Condominiums were successful. It was determined that the sub-contractor hired to install
that particular pipeline walked off the job and never completed the installation. The road
� was saw cut,the area excavated for the installation and the manhole was onsite but the job
was never completed, for whatever reason.
IIn the current submittal, for further review of the Bremerton Townhome project, we will ,
Iinclude the revised design of this pipeline to complete the outlet for the storm drainage I
into the original planned downstream outlet. We will also include a series of KCRTS ,
Istorm water AND backwater calculations to prove that this outlet pipe can safely handle
the 100-year storm flows from this site and the surrounding tributary areas (it can). This
� pipeline will be included as part of the permit package for construction of the Bremerton
' Townhomes project(see plans). �
The site will require substantial grading for the proposed road. The depression along the I!
western property line will need to be filled for approx. 8' in depth. The building pads for the �
lots will also require some minor grading but nothing over 4 feet in depth. The main grading
activity will be associated with the excavation for the detention vault and the fill for the
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Bremerton Townhomes January 2013
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depression. The estimated amount of grading is 500 CY for cut and 4000 CY for fills. It is
anticipated that the site will use some of the cut material on-site, but the majority will be �I
' imported. There are no wetlands, steep slopes or any sensitive/critical areas on this site. There
' is a low depression along the north property line. This depression is approx. 10' deep and
,
extends off-site to the north,with slopes up to the adjacent Bank drive-through driveway. This
jdepression will be filled. The depression was originally a borrow site for filling of the property
to the north(along the bank) and east (the grading for Hillcrest Village Condominiums).
I
_ Along the northern property line of the subject site are three separate properties that will
1 require temporary easements for construction grading and permanent easements for
I future maintenance and storm drainage pipelines. On the western and middle property,
I parcel numbers 7227000000 and 2050500010 easements were recorded in 2008 for the
above easements. These are recording numbers 20080104001145 and 20080104001146.
The final easement was obtained from the property owner on the east for temporary
+ construction access and a permanent easement for future maintenance and the storm
� drainage pipeline in January of 2013 (Recording Number 20130108001739).
IBetween the northern property line of the subject site and the two properties adjacent to it on the
north, is a closed depression that was manmade from previous developments to the north and
east. The detention system from the western property leaves the control structure and outlets '
onto a rock pad that cannot flow anywhere due to the closed depression. The property on the
east has its own detention system that outlets much further to the east in the existing Duvall
� Street conveyance system (therefore we don't have to make any provisions for this tributary
area). We plan to fill this entire closed depression so the grades on the north and south sides
, will essentially be the same.
;
We show on our drawings where we will consh-uct our detention vault and conveyance system
that outlets and flows to the east. At the outlet of the control structure to the north we will
� install a new pipeline from it to our new outlet manhole to tie the underground CMP detention
I
system into our outlet system to Duvall Street. This additional flow in the outlet pipe is
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included in our backwater analysis for the Duvall street corridor to show that we will not create
Iany street flooding from the additional outlet flows from our site.
� The revised location for the detention vault near the northern property line was a new I�
requirement from the City of Renton and required a considerable re-location of �I
I
j underground utilities. The vault will be located in Tract A, please see the drawing set. We
are fully aware that the City requires minimum cover for certain types of pipe materials,
� minimum spacing between utility pipeline underground and other details. We want to be
_, perfectly clear that all of these requirements have been taken into consideration and are
�
� shown in detail on the engineering drawings.
�
I II. CONDITIONS AND REQUIREMENTS SUMMARY
� The SWDM's eight Core Requirements and five Special Requirements are addressed as
' follows:
ICORE REQUIREMENTS:
1. Dischar�e at the Natural Location
� The northern portion of the site currently sheets flow to the north and into the on-site
closed depression by the northern property line and adjacent land to the north. The
southern half of the site is fairly flat, but sheet flows to the southeast corner and recently
developed offsite lots. The local collection point of all of this drainage, prior to recent
, construction, was the existing drainage system in Duvall Ave. NE, east of the site less
than 1/4-mile downstream.
The proposed drainage system will collect runoff in a vault located at the northeast �
' property corner and discharge it through a control structure into an outlet pipe that runs
to the northeast corner of the site. At this point, it will connect to the off-site pipe placed
in an easement (Recording numbers 20080104001145, 20080104001146 and ',
201301080Q1739) and connect into the existing drainage system on the east side of ',,
, Duvall Ave NE. This is the same drainage system into which the existing and
proposed site runoff eventually discharges less than 1/4-mile downstream.
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I Bremerton Townhomes January 2013
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2. Off-Site Analysis
No frontage dedication is required for this project but frontage and street improvements
are a requirement. Frontage gross area is 3010 square feet of which 440 sf will be
1 removed as old asphalt roadway(the existing roadway requires sawcutting about 1.5-
feet back to present a clean edge for the curb and gutter and asphalt roadway entrance).
IThis resolves to 2570 sf(0.4590-acres) of new surfaces in the right of way. The new
impervious surfaces in the right of way consist of 1507 sf(0.0346-acres) of curb and
Igutter and sidewalk. The remaining area is pervious and it totals 1063 sf(0.0244-ac).
�
FRONTAGEIMPROVEMENTS
1
, ' SQUAREFOOTAGE IACREAGE
TOTAL AREA 3010 0.0691
� EXISTING AREA IMPERVIOUS 440 0.0101
IMPROVED AREA TOTAL SF 2570 0.0590 NUMBERS MATCH
iCURB & GUTTER (IMPERVIOUS AREA) 1507 0.0346
LAWN (PERVIOUS AREA) 1063 0.0244 �
I TOTAL AREAS 2570 0.059 NUMBERS MATCH '
1
IAdding the total acreage(0.0590-acres)to the detention calculations mitigates (accounts
for) this total area and any increase in runoff attributed to the frontage will be contained
( and detained in the total vault volume. Please refer to the new KCRTS runoff
calculations below. Essentially, this figure combined with the credits for the rain garden
and permeable pavement result in no net change to the vault volumes.
!� An upstream and downstream drainage analysis is detailed in section III of this report.
I
There are no `Downstream Drainage Problems Requiring Special Attention' or apparent
Idownstream flooding or erosion issues that have been reported per Mr. Gary Fink,
surface water engineer for the City of Renton as of July 24t", 2012. See Appendix D
I
t
i
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� �
j Also,no `Downstream Water Quality Problems Requiring Special Attention' as listed in ,
I � the 2009 Core Requirement No. 2. Such as Bacteria, Dissolved Oxygen, Temperature, ',
Metals, Phosphorus, Turbidity or High pH problems reported. '
�
1
�
3. Flow Control
� This project is a not in a Basic Flow Control Area but is subject to the Full Drainage
Review procedure. This project provides detention to the 2009 King County Leve12
flow control using site specific BMP's from the SWDM to meet the Flow Control
, Duration Standard(for Forested Site Conditions). This Leve12 performance standard
I
� matches flow duration's from one half the 2-year through the 50-year storm event and
, peak flows for the 2- and 10-year events, assuming a predeveloped forested landcover.
i Detention will be provided in a vault with an orifice type flow restrictor(with down-
� turned elbows).
� The fmal interior vault size is controlled by the deck panel width. Therefore the vault is
i
' slightly larger than required. Calculated length is 116.25 feet and the deck panels at 4
� feet wide have the final vault length at 124 feet (31 deck panels @ 4 feet wide). This
Iincreases the vault size about 1418 cubic feet or about 6.4 percent. Concerning the 10
percent Factor of Safety contained in the vault volumes (per the Renton Code), we added
certain BMP's to the project site (permeable paving) that are greater in square footage
I than is required by the Drainage Code. The end result is that the credit we applied to the
� KCRTS drainage calculations for the BMP's and frontage exactly offset the ten percent
� Factor of Safety requirement. In other words, the credits for the BMP's reduced the
� vault size ten percent and then we added back the ten percent for the Factor of
Safety...ie, no net change in volume, see runoff calculations in Appendix A.
4. Conveyance Svstem
The proj ect will provide new conveyance piping and concrete structures for the street
drainage and the roof downspouts (per Code these will be perforated pipe). The main
� conveyance piping will be sized to convey the 100-year developed storm event.
�
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Bremerton Townhomes January 2013
Technical Information Reporf
5. Erosion and Sedimentation Control Plan
I
; An erosion control plan has been prepared and included with the engineering plans.
This erosion control system will include silt fencing along the west, south and east
1 property lines, a construction entrance, seeding &mulching and clearing limits. A
� sediment trap will be designed as part of the initial grading and development of the site
; near the northeast corner of the site and sized as specified in the SWDM. A site log will
be kept with the construction supervisor for the site to record any instances of erosion or
� sediment discharge.
� 6. Maintenance and Operation
� The public road will be dedicated to the City and maintained by the City. The
� Homeowners Association will maintain the private road,joint driveways, alleys and
� drainage vault. Maintenance& Operations cut sheets will be provided in the appendix
as appropriate for this site and the equipment therein.
� 7. Bonds and Liabilitv
1 Appropriate bonding and insurance forms will be secured prior to any construction on
the site.
' 8. Water Quality
I The project is for single family's residential project and will provide �vater quality
` treatment per the Basic Water Quality menu. Proposed treatment is a wetvault, utilizing
I `dead storage' for water quality sediment settling and sediment storage to be combined
with the flow control detention vault.
�
I
Special Draina e Requirements - There are five special drainage requirements that may apply to
Iany project; however, none apply to this project. Note the site is in a Streamflow Source Area
but not an A uifer Protection Area so S ecial Re uirement 5 does not a lv.
� ,
�
q P 9 PP ,
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III. OFFSITE ANALYSIS
� Upstream/ Onsite Flows—The bank on the property to the north (parcel No.'s 7227000000 and
2050500010) is within the subject site due to proposed grading. It has a paved parking azea
�
� with perimeter curbing and drainage that is collected by the pavement/curbing and piped into a
detention tank (subsurface, oversized pipe). The outlet from this detention tank is at the
southeast corner of the bank property. This is adjacent to and flows into the existing on-site
__� depression. The bank drainage discharges to the on-site depression that has no outlet since the
property to the east was recently filled creating the closed depression(apparently the City of
� Renton missed this). The proposed site drainage system will include a separate drainage bypass
pipe that will intercept the discharge from the bank and convey it to the off-site discharge pipe
Iat the northeast corner. A drainage easement has been granted by the landowner.
I From the north end of Bremerton Avenue NW, near 4th Street, the surface drainage flows south
down both east and west curb lmes and mto the catch basins located in Bremerton Avenue, in
� the right of way, at the extreme northwest corner of this site. T'hese flows enter the detention
I pipe for the bank, as noted above. None of these directly affect this site but will be detained and
released into the bypass and thence into the downstream conveyance system offsite. See
backwater analysis for flooding concerns below. '�,
There is minimal flows from Bremerton Avenue NW onto the site, only that which flows off the
extreme eastern edge of the pavement. The contour lines for the street mostly flow towards the
catch basins located near the mid-point of the project site on the west. These flows enter the
; underground drainage system for the development to the west(Ridgeview Court) and are II
delivered downstream away from this site. No changes are proposed to these catch basins and ',
; all frontage improvements, in the right of way, will be conveyed to the west. !
I Downstream - Drainage from the site «-i11 be discharged from the detention vaultiwetvault near
the northeast property corner and into a new 12"conveyance pipe that will run about 10' to the
Inorth property line. At this point, it«ill conriect«-ith the up-stream (bank) drainage bypass
�
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Bremerton Townhomes January 2013
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pipe. It will then turn to the east and run for 50' along the north property line to the northeast
1 corner of the site. At this point, the drainage will exit the property in a 12"pipe to the east (see
I
Figure 2, Downstream Drainage Map). Additional engineering design will be required to
connect the existing underground pipeline to the main conveyance system on the east side of
Duvall Street (see engineering drawings). Locations on the map are keyed to the following
drainage features:
I1. The off-site drainage pipe is located within a drainage easement within the Hillcrest
_� Village Condominiums. The 12"pipe runs approx. 350' due east at 0.40% and across
Duvall Ave. NE.
i 2. The pipe discharges via a Type 2 manhole to a 12"pipe flowing south in the east
I shoulder of Duvall Ave. NE. This 12"pipe runs to the south in the east shoulder of
Duvall Ave NE for approx. 50' to another type 2 manhole.
�
� 3. This type 2 CB has an 18-inch diameter outlet pipe that runs east and into the mini-
storage complex. The drainage will flow through the conveyance system within the
mini-storage complex. There is approx. 650' of piping that runs along the west and
south side of the mini-storage.
4. The piping system discharges into drainage ponds within the mini-storage complex, in
the southeast comer.
' S. The mini-storage drainage pond discharges into a stream located approx. 70' east of the �
� mini-storage site. This stream is a tributary to Maplewood Creek. The pond discharge ,
�
point is approx. 300' south of NE 4th St. The stream is part of a stream/wetland complex
located within the Alder Crossing NGPA.
j 6. The stream flows south���ithin the \iGPA and into a diversion pond constructed by King
i
County. The pond was constructed to divert a portion of the stream flow away from the
I original stream. The original stream flo��� was causing do��-nstream floodinQ problems in
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�
the older Puget Colony Homes Plat. The County installed a new 36"pipe in Field Ave
j NE to provide a diversion route for the stream flow.
� 7. The 36"pipe runs due south within the Field Ave NE ROW. At NE 15` CT, this ROW
becomes part of an area along the eastern boundary of the Laurelhurst Div. 2 plat that
Iwas landscaped and left open as a buffer strip. Recent landscaping and retaining walls
� seem to have hidden some of the drainage structures within the Field Ave ROW. The
36" CPEP pipe continues south to approx. 100' north of NE ls` St.
1 8. At this point, the 36"pipe turns to the southeast and runs through a vacant lot and into
� the cul-de-sac bulb at the west end of NE 1 S` St, in the Puget Colony Homes subdivision.
The 36"pipe then turns to the east and runs along the south side of NE 1 St St. There are
I two type 2 catch basins that were found along this run. The pipe crosses Hoquiam Ave
SE to a type 2 CB in the east shoulder of that road.
I „
9. The 36 i e then turns and runs to the south alon the e t
as ed e of the road avement.
PP g g P
IThere is seven type 2 CB's along this run, from NE lst St to SE 2°a St. These seven CB's
were found m the field.
( 10. There is also a lar e ditch within the east shoulder of Ho uiam Ave SE that flows to the
g q
I south. This ditch displayed running water during a dry period and has signs of high
l flows. The 36"pipe discharges into this ditch just south of SE 136`h St. At this point, the
Iditch flows into a well-defined tributary of Maplewood Creek.
I
Summarv- With the 2009 King County Leve12 detention performance standard in place for this
Iproject, developed runoff from the site should not have an impact on the downstream drainage
� system. By assuming a predeveloped forest landcover, this flow control standard actually ;
� reduces flow durations and peak flows, compared to the existing site, and mitigates impacts of I�,
developed runoff on the downstream system. According to the backwater analysis, no flooding '
� for the 100-year storm event should occur on Duvall Street at the low point by 4`h Avenue.
IP:;'31125 !engineerine;...!'�;�ord r'TIR!Final-Revised TIR 10-26-2012.doc
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Technical information Report
IV. FLOW CONTROL & WATER QUALITY ANALYSIS & DESIGN
I
�
Drainage analysis was performed using the KCRTS hydrology soflware as detailed in the 2009
' King County Surface Water Drainage Manual. Input, output and facility sizing data sheets are
located below.
�
�
A. Existin Sg ite Hvdrology-Drainage from the northern half of this site currently sheet flows
� towards the low depression along the north property line and to the southeast corner. On the
� southern half of the site, surface runoff sheet flows to the southeast. Long pasture grasses, scrub
� shrubs with a few trees and two houses characterize the existing site area, although landcover is
assumed to be entirely till forest for this analysis. There are no drainage improvements on the
� site as it exists now. The existing frontage along Bremerton Ave NE is improved on the west
side only with curb, gutter& sidewalk. Since all developed site drainage will leave at the
northeast corner, the entire 1.84-acre site was used as the single tributary drainage basin.
i
� Total area breakdown:
� Pervious area: 1.84 acres
Ground cover: Till, forest
i2-year peak flow: 0.05 cfs
� 10-year peak flow: 0.09 cfs
' 100-year peak flow: 0.15 cfs ,
� Predeveloped land cover is assumed as forested for these calculations.
�
� B. Developed Site Hydrolo�y - The developed project will include a combination
detention/wetvault located near the southeast corner of the site, under the proposed private road.
� It will be located within a drainage easement and designed to accommodate traffic loading. Site
�
drainage will be routed into the vault using catch basins and pipes located within the new roads.
' Each building will be furnished with a piped drainage stub that will be connected to the street '
�
P:- 31125 /engineering!.../word/TIR/Final-Revised TIR 10-26-2012.doc
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Notes Legend
None Structure s Catchbasin-Type 2 MH
� Catchbasin•Type 1 „ Access Riser
■ Catchbasin-Type1 L Utiliry Vault
� � Concrete/Curb Inlet-Type 4 .« Cleanout
� Drop Inlet Other
� Catchbasin-Type 2 MH . Unknovm Strudure �
1:2,515 � �5� w Catchbasin-Type 1
�210 0 105 21 O Feel � �lity Vault y Catchbasin-Type 2 MH
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North_FIPS_4601 a Catchbasin-Type 1 P� RenOon Maintained
Information TeChnobgy•GIS This map is a user generated static output from an Intemet mapping site and
Cl�Of ��� is for reference mry.Data layers that appear on this map may a may not be
On'`�;,� RentonMapSupport(a�Rentonwa.gov acwrete,cunenl,a otherwise rNiable.
Finance&IT Division 2/27/2013 THIS MAP IS NOT TO BE USED FOR NAVIGATION
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Bremerton Townnomes �anuary ��.
Technical Information Report
drainage system via a perforated downspout connection. The areas used to calculate the flo���
Iwere the same as those areas used in the predeveloped drainage calculations. The impervic�
surfaee was calculatec� n�in� 4nr�(�'�T� n�lti�lines and the de�i�r, area �fthe h�iildin�7s_ narN�.
1
j Total area: 1.� -
Pervious area: 0.76 acrc
IGround cover: till grass
- I
! Imper��ious area: l.U� acres
i Ground co�-er: impervious
I
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2-year peak flo«: U.33 cfs
10-year peak flow: 0.40 cfs
100-year peak flo«�: 0.6? cfs
I
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� Calculating the difference in�-ault size�s ��hen �ve add the 10°�o Factor of Safety back into the
' vault, it was back to the original size, resulting in no net change of volumes. Subtracting about
8 feet and then adding it back on.
C. Performance Standards - Detention Vault - The vault was sized to meet the King County
Leve12 detention performance standard. This standard requires that developed flow durations
match existing flow durations for the range of flows from 50% of the 2-year storm through the
50-year storm. Additionally, developed 2- and 10-year peak flows cannot exceed existing 2-
and 10-year peak flo���s.
�
This results in a detention vault that is 88 feet long by 42 feet wide and 6 feet deep, a volume of
22,176 cubic feet. The 10% Factor of Safety for this vault is 2217 cubic feet, increasing the
� vault length by 8.8 feet. Using the SWDM, and the ability to add BMP's for a credit to the
volume calculation, we revie�ved the procedure and based on the requirements we decided on
� P:'=,112� ;engiueering i...i ���ord'TIR'Final-Revised TIR 10-26-2012.doc
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Bremerton Townhomes January 2013
Technical Information Report
permeable paving for concrete areas in the private portion of the development (nothing in the
' public right of way at all). We followed the flow chart for determining lot BMP requirements
using Figure 5.2.1.A.
1
Using the square foot areas in the table in Appendix G, the total square footage we used was
028-acres or 12,197 square feet of area. Applying the credit to the vault resulted in a
reconfigured vault size of 80 feet long by 42 feet wide and 6 feet deep. The credit was applied
in the usual manner of taking the 0.28 acre and applying 50% as Till Grass and the other _50°��
,..,._ ... _,., , ,, . . . .L-.?..�. .,:? ,, -?,-. T.'r'T?Tc „ ,,,rr .�t;,�,' ,r,,,,� ;,, 1r,,, l,-: ,1 1,_�1-.
Total area: 1.84 acr�
�,
Pervious area: 0.90 acrc,
I Ground cover: till grass
Impervious area: 0.94 acre�
Ground cover: imper�ious
� The new vault to the north is has been reconfigured(due to the right of way width and the
I required setbacks) and that makes the new vault 30 feet wide and 124 feet long. The same
depth of detained runoff will keep the orifice elevations at the same relative elevations.
I The vault sized to this standard contains about 22;692 CF ot storage. The inside dimensions are
I 124 feet long by 30 feet wide(two 15 foot wide cells)with 6.1 feet of live storage (elevation
i� 400' to 406.1'). Duration curves and other vault physical and performance data are below.
i D. Flow Control Svstem - The flow control system designed for this detention system is a
I vertical control structure with 3 orifices (2 upper orifice are down facing with elbows) and the
; `third orifice' is an overflow (at the top of the control structure) for extreme storm events. The
bottom orifice is located on the lowest end of the structure in a horizontal face and is sized per
the KCRTS results to match the release rate of one half the 2-year storm event. The upper
orifice is sized according to the KCRTS and have a different size and elevation location (see
drawings or below in calculated resultsl.
i
P:r'31125 i�engineering?...!word'TIR i Final-Revised TIR 10-26-2012.doc
( Bremerton Townhomes January 2013
Technical Information Report
First Orifice Size 0.70-inch diameter
First Orifice Elevation 398.00 (two feet below outlet elevation in control structure)
' Second Orifice Size 1.40-inch diameter
Second Orifice Elevation 404.10 feet
Overflo�� Elevation 406.10 feet
E. Water Quality Vault—Water quality dead storage will be located under half the detention
_� live storage; i.e., the vault will be an additional5 feet deep under most of its length(not
� including sediment storage). The required dead storage volume is a function of rainfall,
i landcover and a multiplier as follows:
�
V = f(0.9A; + 0.25 A��R
( f=multiplier= 3
A; = area impervious= 1.08 ac(47049 s fl
� At�= area till grass= 0.76 ac (33106 s�
R=precipitation for mean annual storm= 0.041 ft
V = 6,226 cf
i
The dead storage volume provided in the vault is inside dimensions 122 feet by 15 feet by 5 feet
� deep or 9,150 cf.
; V. CONVEYANCE SYSTEMS ANALYSIS AND DESIGN
I
The conveyance system is based on required elements for the City of Renton and
� according to our experience. Actual storm water flows from the site will be at the
calculated release rates and will be of minor overall volumes considering the rainfall
� amounts in this area(larger events do occur and the wet vault is sized accordingly). The
I 12-inch diameter pipes throughout the site are more than adequate to convey the surface
�� P:- 31 125 ; engineering r...:��vord i TIR!Final-Revised TIR 10-26-2412.doc
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Bremerfon Townhomes January 2013
Technical Information Report
runoff and are a requirement from the City of Renton (see backwater calculations below
! for confirmation).
i
� BACKWATER ANALYSIS
This analysis consists of a number of basins that are delineated by property boundaries
�
j and their respective detention systems and the area on Duvall Street. This area is
bounded on three sides by major streets in the area, on the west by Bremerton Avenue;
! on the north by 4th Street and on the east by Duvall Street. Major projects in this area
and built-out with approved and installed detention systems are used as basin tributary
i areas. At the north and west we created Basin 4, which consists of two parcels of land
and one medium sized development project, it is1.8-acres in size. Basin 3 is a large
�� development consisting of three-strip mall shopping areas and a 9-unit townhouse
development (we include all this area because the runoff drainage leaves the site in one
pipe). Basin 3 is 4.2-acres.
�
� Basin 2 is an undeveloped parcel of land and part of Duvall Street, this area is 1.1-acres.
Basin 1 is the remaining portion of Duvall Street by the 18-inch diameter outlet pipe for
the entire tributary drainage area. The final Basin is the Bremerton Townhouse project,
which is 1.84-acres total. All basins have been calculated using the 100-year storm '�
event as the base flow. As you can see from the color plate in Figure 6 below, «-c ha�e
shown the basins and the pipelines connecting them all. Each pipe is labeled and
corresponds to the calculations from the KCBW modeling program printouts in the
Appendix below. All nodes have elevation, ,��s��ciatc�� «�it1� the��i h�,�ed �r. th� curr;�n:
survey form the site and surroundin`� ��r��:.
l_)I)C� i�',� ,.']�.:\�l� ',��1� C�`�111���1.I�'. �t � �lllV�� C�_�Il;j�;?i'��j :��� �l� .'l��l ti..,�l'<l �� �i , �'
�� �:' ��,C1 ��1110I1
' in a structure or a pipe to the lowest elevation point of a catch basin rim where draina«
runoff could exit. The highest runoff elevation in a structure or pipe is 396.60 feet anc
i the lowest rim elevation is 397.35 feet, the difference is 0.75 feet or a 9-inch differential.
� Therefore, we believe and are showing that no overtopping of the lowest catch basin rim
i
I P: �ll 2� - engineering;...� �vord i TIR'Final-Revised TIR 10-26-201�.doc
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I Bremerton Townhomes January 2013
Technical Information Reporf
will occur for the 100-year storm. This is further proven by the fact that no flooding
jproblems have ever been called in as a complaint to King County for Duvall Street.
fSee Backwater Analysis calculations in Appendix B below I
iVI. SPECIAL REPORTS AND STUDIES ;
In addition to the Technical Information Report (TIR), a geotechnical report was created
from the previous owners of the site and will be located in the Appendix.
' I VII. OTHER PERMITS AND EASEMENTS �
An Administrative Site Plan and a Conditional Use Permit (CUP) was originally
! I� submitted and approved for this small sub-division but due to factor beyond anyone's
I
I control, it expired. The Site Plan and CUP was re-submitted this year and approved on
May 21, 2012. Within the CUP are additional reports and exhibits such as the Hearing
I Examiners report and decision and other pertinent information. The City of Renton
produced this document therefore it is not included in this document. Existing
Ieasements associated with this project are included in this report in the Appendix
IVIII. CSWPPP ANALYSIS AND DESIGN
The Temporary Erosion and Sedimentation Control Plan as shown in the engineering
� plan set is sufficient for stabilizing this project. If, for any reason, the project becomes
' stalled by time or weather all measures for controlling the erosion and sedimentation
i should be closely followed and shown in the SWPPP. Additionally, the contractor
� •
should perform a site visit during or after every major storm event to minimize and
Ieffects from the rainfall.
� IX. BOND QUANTITIES, FACILITY SUMMARIES AND DECLARATION OF
COVENANT
This portion of the TIR will not be calculated or provided until after the first review
comments come back from the City of Renton.
I P:;� �112� �enoineerine -"...;'word i TIR I Final-Revised TIR 10-26-2012.doc
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IBremerton Townhomes January 2013
� Technical Information Reporf
X. OPERATIONS AND MAINTENANCE MANUAL
See Appendix for relevant O &M tables from the SWDM.
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Bremerton Townhomes January 2013 ',
Technical Information Report �i
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1 APPE�V�IX A
I KCRTS RUNOFF CALCULATIONS I
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ITill�vrest 1.84 acr�s.
Tii["Pasture tt:0� acres�
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(�utwash forest f1.00 acres.
It3u#wasb Pa�ture [�'.00 acras
Outwas� Grass Q=OQ acr�s:
� V�letlantl �:QO ac�e�.
Impervia�ts �;:00 �t�e�:
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1.84 acres
� Sca[e Factor: 1.II0 Hnu Red�ed
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Flow Frequency Analysis
Time 5eries File:�re.tsf
� Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
� (CF5) (CFS) Period
0.116 2 2/09/O1 18:00 q.148 1 100.00 0.990
0.032 7 1/06/02 3: 00 0.116 2 25.00 0. 960
l 0.086 4 2/28/03 3:00 0.089 3 10.00 0. 900
0.003 8 3/24/04 20:00 0.086 4 5.00 0.800
0. 051 6 1/05/05 8.00 0.075 5 3.00 0. 667
0.089 3 1/18/06 21: 00 0.051 6 2.00 0.500
l 0. 075 5 11/24/06 4:00 . 32 7 1.30 0.231 ,
� 0.148 1 1/09/08 9:00 0.003 8 1. 10 0.091
� Computed Peaks 0.138 50. 00 0. 980
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Area ..___ __ . � ..::1
I Till Faresf 0.00 acres; �.C_ '�
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- TiII Pasture 0.00 acres'
� Till Grass' 0.90 acres
Ou#►assh Farest' �.�0 acres'
I 0.00 acres
��utwash Rasture'�
Outwash Grass Q.00 acresi
I 1hlefland' O.Oa acresii
Impervious' 0.94 acres',
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To#al _..
' 1.84 acres:
Scate Factor : 1.00 Hourly� Reduced � �
Time Series: DEV� »
ICampute Time Series (
. Madify User Input �
� _ ____: _...-- ___.: __ . _ ___ . __..__ _..__ _____
File for computed Time Series [.TSF�
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Retention/Detention Facility
Type of Facility: Detention Vault
--� Facility Length: 80.00 ft
Facility Width: 42.00 ft
Facility Area: 3360. sq. ft
, Effective Storage Depth: 6.00 ft
l Stage 0 Elevation: 400.00 ft
Storage Volume: 20160. cu. ft
Riser Head: 6.00 ft
I Riser Diameter: 12.00 inches
Number of orifices : 2
Full Head Pipe
------111 Orifice # Height Diameter Discharge Diameter
I (ft) (in) (CFS) (in)
� 1 0.00 0.70 0.033
2 3.45 1.20 0.062 4 .0
� Top Notch Weir: None
Outflow Rating Curve: None
l Stage Elevation Storage Discharge Percolation
� (ft) (ft) (cu. ft) (ac-ft) (cfs) (cfs)
0. 00 400.00 0. 0 .000 0.000 0 .00
I 0 .01 400.01 34. 0.001 0.002 0.00
j 0 .02 400.02 67. 0.002 0.002 0.00
0. 03 400.03 101. 0.002 0.002 0.00
0. 04 400.04 134. 0.003 0 .003 0.00
I 0.05 400.05 168. 0.004 0 .003 0. 00
0.06 400.06 202. 0.005 0.003 0. 0a
0. 16 400.16 538. 0.012 0.005 0. 00
I 0.26 400.26 874. 0.020 0.007 0.00
0.36 400.36 1210. 0.028 0.008 0.00
0.46 400.46 1546. 0.035 0.009 0.00
0.56 400.56 1882. 0.043 0.010 0.00
I 0.66 400.66 2218. 0.051 0.011 0 . 00
0.76 400.76 2554. 0.059 0 .012 0 . 00
0.86 400.86 2890. 0.066 0.012 0. 00
0.96 400 .96 3226. 0.074 0. 013 0. 00
I 1.06 401.06 3562. 0.082 0. 014 0. 00
1. 16 401.16 3898. 0 .089 0. 014 0.00
1.26 401.26 4234. 0 .097 0.015 O.QO
I 1.36 401.36 4570. 0.105 0.015 0.00
1.46 401.46 4906. 0.113 0.016 0 .00
1.56 401.56 5242. 0.120 0.017 0 .00
1 .66 401.66 5578. 0.128 0 .017 0. 00
I 1.76 401.76 5914. 0.136 0.018 0.00
1.86 401.86 6250. 0.143 0.018 0 . 00
1. 96 401.96 6566. 0 .151 0 .019 0 . 00
2 .06 402 .06 6922. 0 .159 0 .019 0 . 00
2 . 16 402 .16 7258. 0 .167 0 . 020 0. 00
2 .26 402 .26 7594. 0.174 0. 020 0.00
2.36 402.36 7930. 0.182 0. 020 O. CO
I 2 .46 402 .46 8266. 0.190 0.021 0.00
2 . 56 402 .56 8602 . 0.197 0.021 0 . 00
� G .76 402 .�6 9274 . G .213 0.022 0 . �I
2 .86 402.86 9610. 0.221 0.022 0 . '
� 2 .96 402.96 9946. 0.228 0.023 0.
3.06 403 .06 10282. 0.236 0 .023 0.
� 3 .16 403 .16 10618. 0.244 0 .024 0.00
3 .26 403.26 10954. 0 .251 0.024 0.00
3 .36 403 .36 11290. 0.259 0 .024 0.00
I 3 .45 403 .45 11592. 0.266 0 .025 0.00
3 .46 403 .46 11626. 0.267 0.025 0. 00
3 .48 403 .48 11693 . 0.268 0.026 0. 00
3 .49 403.49 11726. 0.269 0.027 0.00
I 3.50 403 .50 11760. 0.270 0.030 0.00
3.51 403 .51 11794 . 0.271 0. 032 0. 00
3 .53 403 .53 11861. 0.272 0. 036 0.00
3 .54 403.54 11894. 0.273 0.037 0.00
� 3 .55 403 .55 11928. 0.274 0.037 0.00
3 .65 403 .65 12264 . 0.282 0. 043 0.00
3.75 403 .75 12600. 0.289 0. 047 0.00
I 3 .85 403 .85 12936. 0.297 0.051 0.00
3 .95 403 .95 13272. 0.305 0.054 0.00
4.05 404.05 13608. 0.312 0.057 0.00
4.15 404.15 13944. 0.320 0.060 0.00
I 4 .25 404.25 14280. 0.328 0.062 0.00
4 .35 404 .35 14616. 0 .336 0.065 0.00
4.45 404 .45 14952. 0.343 0 .067 0.00
I 4.55 404.55 15268. 0.351 0 .069 0.00
4 .65 404.65 15624. 0.359 0.071 0.00
4 .75 404 .75 15960. 0.366 0.074 0.00
4 . 85 404 .85 16296. 0.374 0.075 0.00
I 4. 95 404 .95 16632. 0.382 0.077 0. 00
5.05 405.05 16968. 0.390 0. 079 0. 00
5.15 405.15 17304. 0.397 0. 081 0.00
I 5.25 405.25 17640. 0.405 0.083 0.00
5.35 405.35 17976. 0.413 0.085 0.00
5.45 405.45 18312. 0.420 0.086 0.00
5 .55 405.55 18648. 0.428 0.088 0.00
I 5.65 405 .65 18964. 0.436 0 .090 0.00
5.75 405 .75 19320. 0.444 0 .091 0.00
5.85 405.85 19656. 0.451 0 .093 0.00
5.95 405.95 19992 . 0.459 0 . 094 0.00
I 6. 00 405.00 20160. 0.463 0. 095 0. 00
6. 10 406.10 20496. 0.471 0.404 0. 00
6.20 406.20 20832. 0.478 0.969 0. 00
I 6.30 406.30 21168. 0.486 1. 700 0. 00
6.40 406.40 21504. 0.494 2 .490 0. 00
6.50 406.50 21840. 0.501 2 .780 0. 00
6.60 406.60 22176. 0.509 3 . 030 0. 00
I 6.70 406.70 22512. 0 .517 3 .270 O. CC
6.80 406 .80 22848. 0.525 3 .490 0. 00
6.90 406 .90 23184. 0.532 3 .700 0. 00
I 7.00 407.00 23520. 0.540 3 . 690 0 .00
7.10 407.10 23856. 0.548 4 . 080 0 .00
7.20 407.20 24192 . 0.555 4 .250 0.00
7.30 407 .30 24528 . 0.563 4 .420 0.00
7.40 407 .40 24864. 0.571 4 .590 0.00
7.50 407.50 25200. 0.579 4 . 750 0. 00
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7 .60 407.60 25536. 0.586 4.900 0.00
7.70 407.70 25872. 0.594 5.050 0.00
I 7.80 407.80 26208. 0.602 5.190 0.00
7. 90 407.90 26544. 0.609 5.330 0.00
-� Hyd Inflow Outflow Peak Storage
Target Calc Stage Elev (Cu-Ft) (Ac-Ft)
1 0.63 0.15 0.39 6.10 406 . 10 20480. 0.470
2 0.31 ******* 0.09 5.79 405 .79 19460 . 0.447
I 3 0 .37 ******* 0.08 4.86 404 . 86 16341. 0.375
4 0.31 ******* 0.08 4. 93 404 .93 16569. 0.380
� 5 0.33 ******* 0.06 4.09 404 . 09 13736. 0.315
6 0.19 ******* 0.04 3.58 403 .58 12028 . 0.276
j I 7 0.24 ******* 0.02 3 .20 403 .20 10762 . 0.247
8 0.25 ******* 0.02 2.01 402 .01 6743 . 0.155
----------------------------------
� Route Time Series through Facility
Inflow Time Series File:dev.tsf
IOutflow Time Series File:rdout
I� Inflow/Outflow Analysis
� Peak Inflow Discharge: 0.635 CFS at 6:00 on Jan 9 in Year 8
( Peak Outflow Discharge: o.389 CFS at 10 :00 on Jan 9 in Year 8
Peak Reservoir Stage: 6.10 Ft
Peak Reservoir Elev: 4�6.10 Ft
� Peak Reservoir Storage: 20480. Cu-Ft
0.470 Ac-Ft
Flow Frequency Analysis
Time Series File:rdout.tsf
I � Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
I Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
(CFS) (CFS) (ft) Period
0.093 2 2/09/Ol 21:00 0.389 6.10 1 100 .00 0. 99G
I 0.024 7 1/07/02 4:00 0 .093 5.87 2 25.00 0. 960
0.075 4 3/06/03 22:00 0 .077 4.93 3 10.00 0. 900
0.019 8 8/26/04 8:00 0 .075 4.87 4 5.00 0. 800
' 0.039 6 1/08/05 1:00 0 .058 4 .09 5 3 .00 0.667
I 0.058 5 1/19/06 1:00 0 .039 3 .56 6 2 . 00 0.500
0 .077 3 11/24/06 9:00 0 .024 3 .24 7 1.30 0.231
0 .389 1 1/09/08 10 :00 0 .019 2 .01 S 1.10 0 . 091
Computed Peaks 0.290 6.06 50 .00 0. 980
I F1 w D n f
o uratio rom Time Series File:rdout.tsf
Cutoff Count Fre uenc CDF Exceedence Probabilit
q Y _ Y
1 �FS � � �
0.001 30903 50.396 50.396 49.604 0.496E+00
0.004 7200 11.742 62 .138 37.862 0.379E+00
0.007 4506 7.348 69.486 30.514 0.305E+00
0.009 4879 7.957 77.443 22.557 0 .226E+00
0.012 3476 5.669 83 .112 16.888 0.169E+00
0 .014 4276 6. 973 90.085 9. 915 0. 992E-01
I 0 .017 1633 2 .663 92.748 7.252 0 .725E-01
0 .020 1575 2 .568 95.316 4 .684 0 .468E-01
O . C22 �415 2 . 308 9�.524 2 .3�6 0 .238E-01
0 .025 911 1.486 99.110 0. 890 0.890E-02
0.027 110 0. 179 99.289 0.711 0 .711E-02
0.030 16 0 .026 99.315 0.685 0 .685E-02
0.033 27 0.044 99.359 0.641 0.641E-02
_� 0.035 11 0.018 99.377 0.623 0.623E-02
0.038 30 0.049 99.426 0.574 0.574E-02
0.040 28 0.046 99.472 0.528 0.528E-02
I 0.043 24 0.039 99.511 0.489 0.489E-02
I 0.045 28 0.046 99.556 0.444 0.444E-02
0.048 33 0.054 99.610 0.390 0.390E-02
0. 051 20 0.033 99.643 0.357 0.357E-02
I 0.053 21 0.034 99.677 0.323 0.323E-02
0.056 20 0.033 99.710 0.290 0.290E-02
0.058 22 0.036 99.746 0.254 0.254E-02
0.061 27 0.044 99.790 0.210 0.210E-02
� 0.064 21 0.034 99.824 0.176 0.176E-02
0.066 7 0.011 99.835 0.165 0.165E-02
0.069 15 0.024 99.860 0.140 0.140E-02
I0.071 12 0.020 99.879 0.121 0.121E-02
I 0.074 9 0.015 99.894 0.106 0.106E-02
0.077 23 0.038 99.932 0.068 0.685E-03
0. 079 5 0.008 99.940 0.060 0.603E-03
I 0.082 4 0.007 99.946 0.054 0 .538E-03
0.084 8 0.013 99.959 0.041 0 .408E-03
0.087 10 0.016 99.976 0.024 0.245E-03
� 0.090 4 0.007 99.982 0.018 0.179E-03
0.092 6 C.O10 99.992 0.008 O . B15E-04
Discharge Volume
IDischarge Volume from Time Ser�es
rdout.tsf
I between io/oi/oo oo:oo ana io/3o/00 23 :59
24642 . Cu-Ft or 0.570 Ac-Ft in 30 .0 days ��� �`��� :��
L,�;_�.:,�,; --�-�.`..
Duration Comparison Anaylsis �` �'�'�'/�: �°j,�,^
Base File: pre.tsf y ~� `- C'.�=;;-,
I New File: rdout.tsf �� `_�
Cutoff Units: Discharge in CFS
-----Fraction of Time----- ---------Check of Tolerance------- `
I Cutoff Base New �Change Probability Base New �Change �
0. 025 � 0.99E-02 0.85E-02 -13 .7 � 0.99E-02 0.025 0.024 -2.0
0. 032 � 0 .64E-02 0.65E-02 1.8 I 0 .64E-02 0.032 0 .032 1. 8 ��.`` �,
I 0. 039 I 0.50E-02 0 .55E-02 10.4 � 0 .50E-02 0.039 0. 042 8. 1 ,
0.046 � 0 .38E-02 0.44E-02 15.5 � 0 .38E-02 0.046 0.049 5.9 � �"
0.053 � 0 .29E-02 0.33E-02 14 .2 � 0 .29E-02 0.053 0.056 6.3 -, ��= �.
0.060 � 0 .22E-02 0.23E-02 5.1 � 0.22E-02 0.060 0 .060 0. 7 ��'S ��
1 0.067 I 0.15E-02 0.15E-02 1.1 ( 0.15E-02 0.067 0 .067 0.5 �� �'�
0.074 � O .10E-02 0. 11E-02 6.3 I O.10E-02 0.074 0.074 0.7 � �
0.081 I 0 .62E-03 0.55E-03 -10 .5 I 0.62E-03 0.081 0.078 -3 .0 "��=='`'
, 0.088 I 0 .34E-03 0.23E-03 -33.3 I 0 .34E-03 0.088 0 .085 -2 .6 ,,.�
� 0.095 � 0.23E-03 O.00E+00 -100.0 � 0 .23E-03 0. 095 0 .088 -7 .1 ��,
� 0.102 I 0 . 16E-03 O.00E+00 -100.0 � 0 . 16E-03 0. 102 0.090 -11.5 r
0.109 � 0 . 11E-03 O.00E+00 -100.0 � 0. 11E-03 0.109 0.091 -15.9 -
0 . 116 I 0 . 16E-04 O .00E+00 -100 . 0 j 0 . 16E-0� 0 .116 0 . 093 -19.5 �/�
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I Maximum positive excursion = 0.003 cfs ( 10.0�) �— a '/''�lm VM '�_,�i';�1 V� g;���2 �
occurring at 0 . 034 cfs on the Base Data:pre.tsf � ���-�
j and at 0 .037 cfs on the New Data:rdout.tsf /��S�l` �:: Li.-_,�� �
'�� �� �`,.7 'Cj�
Maximum negative excursion = 0.023 cfs (-19.5�) ,� �
__{ occurring at 0 .116 cfs on the Base Data:pre.tsf G,�,��
� and at 0.093 cfs on the New Data:rdout.tsf ?
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HOW TO SIZE A LEVEL 2 (STREAM PROTECTION� FACILITY
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I The routine compares the flow durations of both time series and displays
� this table in the Help/Files - KCRTS w-indo��-:
� _
. �' = ,y�J
- � Durati�n-Comparison_Anaylsis v �
t Base File: predev.tsf
� New File: rdout.tsf
� �Cutoff Units__Discharge in CFS _----- .
� --Fraction of Time---- - --Check of Tolerance-------
�= Cutoff Base New %Change Probability Base New iChange
�� �.160 � 0.69E-02 0.71E-02 -20.1 � 0.89E-02 0.160 0.156 -2.4
0.199 � 0.62E-02 0.43E-02 -31.7 � 0.62E-02 0.199 0.166 -16.8
( � 0.238 � 0.49E-02 0.35E-02 -27.9 I 0.49E-02 0.238 0.186 -21 8
� 0.277 � 0.37E-02 0.30E-02 -17.8 � 0.37E-02 0.277 0.228 -17 8
� 0.316 � 0.28E-02 0.29E-02 1.2 � 0.28E-02 0.316 0.322 1 9
� 0.355 � 0.22E-02 0.29E-02 12.8 � 0.22E-02 0.355 0.375 S i
� :; 0.394 � 0.15E-02 0.19E-02 26.1 � 0.15E-02 0.394 0.412 4.6
0.433 � O.10E-02 0.11E-02 7.B � O.10E-02 0.433 0.441 1.8
0.472 � 0.64E-03 0.75E-03 17.9 I 0.64E-03 0.472 0.491 3 9
" 0.512 I 0.38E-03 0.34E-03 -8.7 � 0.38E-03 0.512 0.510 -0 2
�' 0.551 � 0.21E-03 0.23E-03 7.7 � 0.21E-03 0.551 0.555 0 9
I ? 0.590 � 0.15E-03 0.33E-04 -77.8 I 0.15E-03 0.590 �.570 -3 3
� 0.629 � 0.98E-04 0.33E-04 -66.7 � 0.98E-04 0.629 0.580 -7 S
D.668 � 0.16E-04 0.16E-04 0.0 � 0.16E-04 0.668 0.700 4 8
I iMaximum positive excursion = 0.048 cfs ( 7 3i)
;occurring at 0.652 cfs on the Base Data:predev r,f �
iand at 0.700 cfs on the Nev Data:rdout.tsf
= J �
� ��- ��_ � , _ _.' : ►J.,
� The cutoff values selected by the routine are shown in the first column.
The corresponding fraction of time exceeded of each time series is
1 displayed in Columns 2 and 3 with the percent change in time exceeded
displayed in Column 4. The right half of the table compares the duration
curves vertically. Column 8 (last column) is the check of allowable
I tolerance.
The following conditions must be met:
-- _.�-�--�_l---�.�_`�_�_,�'`
STEP 22. ■ First cutoff must have a percent change (last column)
equal to or less than 0.0.
i ■ The remaining cutoffs must have a value less than
positive 10.0 percent.
� ■ At least one-half of the cutoffs must have a zero or
I negative percent change.
■ Note the absolute maximum positive and negative
vertical excursions found at the bottom of the table.
■ The maximum positive excursion must be less than
positive 10.0 percent.
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November 1, 2009 ��� ::CRTS lise:'s Guide tiTl-29
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I 100-year discharge
Worksheet for Circular Channel
Project Description ( i �j �
Project File untitled.fm2 � �A
Worksheet �oc �
� � L �.
Flow Element Circular Channel
Method Manning's Formula
SoNe For Channel Depth
I Input Data ,
Mannings Coefficient 0.009 -
Channel Slope 0.007400 ft/ft
Diameter 12.00 in
� Discharge 0.39 cfs t j
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I Resutts
� Depth 0.20 ft
Flow Area 0.11 ftz � - -r. -::
I Wetted Perimeter 0.93 ft
Top Width 0.80 ft
Critical Depth 0.26 ft
I Percent Full 20.03 ;
Critical Slope 0.002701 ft/ft
Velocity 3.47 ft/s
I Velocity Head 0.19 ft
Specific Energy 0.39 ft
Froude Number 1.63
� Maximum Discharge 4.76 cfs
Full Flow Capacity 4.43 cfs
Full Flow Slope 0.000057 ft/ft
IFlow is supercritical.
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10l26/12 FlowMaster v5.11
01:40:57 PM Haestad Methods, Inc. 37 Brookside Road Vlhaterbury,CT 06708 (203)755-1666 Page 7 of 1
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� Bremerfon Townhomes January 2013 ,
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� Technical Information Reporf
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APPENDIX B
I KCRTS BACKWATER CALCULATIONS
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BACKWATER COMPUTER PROGRAM FOR PIPES
Pipe data from file:Pl.bwp
Surcharge condition at intermediate junctions
_� Tailwater Elevation:394.5 feet
Discharge Range:3.4 to 3 .5 Step of 0.02 [cfs]
Overflow Elevation:406.1 feet
Sharp Crested Weir: Length:l. feet, Height:6. 1 feet
( Upstream Velocity:l. feet/sec
� PIPE N0. 1: 20 LF - 18"CMP Q 0.35� OUTLET: 394.50 INLET: 394 .57 INTYP: 2
JUNC N0. l: OVERFLOW-EL: 402.16 BEND: 90 DEG DIA/WIDTH: 4 .0 Q-RATIO: 0 .07
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
� *************************************,r*****************************************
3 .40 1.28 395. 65 * 0.024 0 .71 1.25 0. 00 0 . 71 1.02 1.28 1. 10
3 .42 1.28 395.85 * 0.024 0.71 1.26 0.00 0. 71 1 .02 1.28 1. 10
�����P 3 .44 1.29 395. 86 * 0.024 0 .71 1.27 0.00 0. 71 1.03 1.29 l.11
� �'r4lL-ivtjt�{�-�
3 .46 1.30 395.87 * 0.024 0.72 1.29 0 .00 0.72 1.03 1.30 1. 12
3 .50 1.30 395.87 * 0.024 0.72 1.30 0 .00 0.72 1.03 1.30 1. 12
� PIPE NO. 2 : 47 LF - 12"CP � 0 .09� OUTLET: 394 . 66 INLET: 394 .70 INTYP: 2
JUNC NO. 2 : OVERFLOW-EL: 401.85 BEND: 90 DEG DIA/WIDTH: 4 . 0 Q-RATIO: 2 .74
lQ(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
*******************************************************************************
I3 .18 1. 86 396.56 * O.D12 0.77 1.00 1.19 1.19 1.47 1. 86 1.32
�p�;_ r 3 .20 1. 87 396.57 * 0.012 0.77 1.00 1.19 1.19 1.48 1. 87 1.33
�,���.3��� a 3 .21 1. 89 396.59 * 0.012 0.77 1.00 1.20 1.20 1.49 1. 89 1 .33
) 3 .25 1. 91 396.61 * 0.012 0 .78 1.00 1.21 1.21 1.50 1. 91 1 .35
I 3 .27 1. 92 396.62 * 0.012 0.78 1.00 1.21 1.21 1.51 1. 92 1.36
I PIPE NO. 3 : 85 LF - 15"CP Q 0.02$ OUTLET: 394 .70 INLET: 394 .72 INTYP: 2
� JUNC NO. 3 : OVERFLOW-EL: 404.82 BEND: 0 DEG DIA/WIDTH: 4 . 0 Q-RATIO: 0.00
� Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
*******************************************************************************
0. 85 1. 86 396.58 * 0.012 0 .37 0 .84 1.86 1. 86 1 . 86 1.85 0 .48
0. 85 1. 86 396.58 * 0.012 0.37 0.85 1.87 1.87 1 . B6 1.86 0.48
�'�'p"�F 0. 86 1. 88 396.60 * 0.012 0.37 0. 85 1.89 1.89 1.88 1.88 0.48
�,s�.;��� ?
0 . 87 1.91 396.63 * 0.012 0.37 0 . 86 1.91 1.91 1 . 91 1.90 0.48
_I 0. 87 1.92 396.64 * 0.012 0.37 0 . 86 1.92 1.92 1.92 1.91 0.48
PIPE NO. 4 : 262 LF - 12"CP @ 0.38$ OUTLET: 396. 97 INLET: 397. 97 INTYP: 2
IJLTNC N0. 4 : OVERFLOW-EL: 407. 00 BEND: 0 DEG DIA/WIDTH: 4 . 0 Q-RATIO: 0 . 00
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
1 *******************************************************************************
0.65 0 .57 398.54 * 0.012 0 .39 0 .42 0. 00 0. 39 0 .42 0.57 0 .52
i . .
' 0. 85 0 .58 398.55 * 0.012 0.39 0 .42 0.00 0.39 0 .42 0.58 0.52
�DO-yr 0.86 0 .58 398.55 * 0.012 0.39 0 .42 0.00 0.39 0 .42 0.58 0.52
U3���?�
0. 87 0.58 398.55 * 0.012 0.40 0.42 0.00 0.40 0.42 0.58 0.53
0. 87 0 .58 398.55 * 0.012 0.40 0 .42 0 .00 0.40 0 .42 0 .58 0 . 53
�
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' PIPE NO. 5 : 76 LF - 12"CF .. 0.50E OUTLET: 397 . 9? �N�ET: 398 .35 INTYF : 1
JUNC NO. 5 : OVERFLOW-EL: 409.00 BEND: 90 DEG DIA/WIDTH: 4.0 Q-RATIO: 1. 10
� Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
Yc�F Yr****W*�t****�FYt******1t*Yt*Yt�F*�t�t*�tir�F*Yt*�tY[tF*Yf*yt***�t*�t�t�t*Yt�t�t*Yr****�t**Yc*Yc:tYt�k�t******
I 0.85 0 .66 399.01 * 0.012 0.39 0.39 0 .57 0.57 0.39 0.66 0.57
�r 0.85 0 .66 399.01 * 0.012 0.39 0.39 0 .58 0.58 0.39 0.66 0.57
�� � 0. 86 0.67 399.02 * 0.012 0. 39 0.39 0 .58 0.58 0.39 0.67 0.57
(,t3�f���
� 0. 87 0.58 398. 93 * 0.012 0.40 0 .39 0 .58 0.58 0.40 ***** 0 . 58
0. 87 0 .58 398. 93 * 0.012 0.40 0.39 0 . 58 0 .58 0.40 ***** 0 .58
� PIPE NO. 6 : 9 LF - 12"CP C 18. 33� OUTLET: 398 .35 INLET: 400 .00 INTYP: 1
(
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
I ******************************************,r************************************
0.40 0 .27 400.27 * 0.012 0.27 0.11 0 .66 0.66 0.27 ***** 0 .26
0.41 0.27 400.27 * 0.012 0.27 0.11 0 .66 0.66 0.27 ***** 0.26
��'�1` �ja� 0.41 0.27 400.27 * 0.012 0.27 0.11 0.67 0.67 0.27 ***** 0.26
I� _` -� 0.41 0 .27 400.27 * O.C12 0.27 0 . 11 0 .58 0 .56 0 .27 ***** 0 .27
0 .42 0 .27 400.27 * C .012 0 .27 0 . "�l 0 . 58 0 .58 � .27 **"'** 0 .2?
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Area------_ _ . ?�
I Till Forest' 0.00 acres:
Ti[I Pasture 0.00 acres;
1 TiIF Grass 0.00 acres,
Ou#wash Forest �•DO acres' '
� Outwash Pasture 0.00 acres;
' Outv►ash Grass' 0.00 acres
I V�le#land' 0.00 acres'
Impervious, 0.20 acres,:
� ;-Total_.__ .. �_�
0.20 acres'
I Scale Factor : 1.00 15-Min Reduced
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Time Series: B11 >? 1
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� Flow Frequency Analysis
Time Series File:bl.tsf
I Project Location:Sea-Tac ,
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---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
I Flow Rate Rank Time of Peak --Peaks-- Rank Return Prob I
(CFS) (CFS) Period
0.095 6 8/27/0118:00 0.236 1 100.00 0.990
0.066 8 9/17/0217:45 0.180 2 25.00 0.960 !,
I 0.180 2 12/08/0217:15 0.129 3 10.00 0.900 I
0.077 7 8/23/0414:30 0.107 4 5.00 0.800
0.101 5 10/28/0416:00 0.101 5 3.00 0.667
0.107 4 10/27/OS 10:45 a.095 6 2.00 0.500
I 0.129 3 1Or25/06 22:45 0.077 7 130 0.231 I
0.236 1 1/09/08 6:30 0.066 8 1.10 0.091
Computed Peaks 0.217 50.00 0.980 I
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Till Forest 0.00 acres
; Till Pasture' 0.00 acres
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' Till Grass 0.00 acres'
Outwash Forest 0.00 acres;
dutwash Pasture 0.00 acres'
Outwash Grass 0.00 acres'
� Wetland 0.00 acres;
Impervious 1.10 acres'
_-------
� ;--Total _ _____,
', 1.10 acres'
, _._ ____ ___----.
� Scale Factor : 1.U0 15-Min Reduced
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Flow Frequency Analysis
Time Series File:b2.tsf
I Project Location:Sea-Tac
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� ---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak --Peaks-- Rank Retum Prob
i I (CFS) (CFS) Period
0.524 6 8/27/0118:00 1.30 1 100.00 0.990
I 0.366 8 9/17/0217:45 0.991 2 25.00 0.960
j 0.991 2 12/08/0217:15 0.711 3 10.00 0.900
I 0.422 7 8/23/0414:30 0.586 4 5.00 0.800
0.555 5 10/28/0416:00 0.555 5 3.00 0.667
0.586 4 10/27/0510:45 0.524 6 2.00 0.500
` 0.711 3 10/25J06 22:45 0.422 7 130 0.231
� 1.30 1 1/09/08 6:30 0366 8 1.10 0.091
Computed Peaks 1.20 50.00 0.980
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' Till Forest 0.00 acres
� Till Pasture U.00 acres
Till Grass O.dO acres
I Ouiwash Fore$t', 0.00 acres
Outwash Rasture! D.00 acres
Outwash Grass; 0.00 acres� �
� Wetlandj 0.00 acres'
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Impervious� 1_40 acres
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! Scale Factor : 1.00 Hourly Reduced
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File for computed Time Series [.TSFJ
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Flow Frequency Analysis
Tune Series File:b3.tsf
I Project Location:Sea-Tac
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---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
I Flow Rate Rank Time of Peak --Peaks -- Rank Return Prob
(CFS) (CFS) Period
0.896 6 2/09/O1 2:�0 1.77 1 100.00 0.990
0.763 8 1/OS/0216:00 1.25 2 25.00 0.960
I 1.07 3 12/08/02 18:00 1.07 3 1�.00 0.900
{ 0.862 7 8/26/04 2:00 1.03 4 5.00 0.800
1.03 4 10/28/0416:00 0.955 5 3.00 0.667
I 0.955 5 1/18/0616:00 0.896 6 2.00 0.500
1.25 2 10/26/06 0:00 0.862 7 1.30 0.231
1.77 1 1/09/08 6:00 0.763 8 1.10 0.091
Computed Peaks 1.60 50.00 0.980
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' Till Forest 0.00 acres'
_� Till Pasture 0.00 acres'
Till Grass 0.40 acres'
Outwash Forest O.UU acres'
( Outwash Pasture 0.00 acres'
Outwash Grass O.OQ acres'
IWetland 0.00 acres'
Impervious 1.40 acres'
� _ ______ _ _ __
- Total-
1.80 acres
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I Scale Fa�ctor : 1.00 Haurly Reduced
Time Series: B4 ?>
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Time Series File:b4.tsf
Project Location:Sea-Tac
I ---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
! Flow Rate Rank Time of Peak --Peaks-- Rank Return Prob
(CFS) (CFS) Period
I 0.375 6 2/09/O1 2:00 0.746 1 100.00 0.990
0.317 8 1/OS/0216:00 0.518 2 25.00 0.960
0.448 3 12/08/0218:00 0.448 3 10.00 0.900
0.356 7 8/26/04 2:00 0.426 4 5.00 0.800
I 0.426 4 10/28/0416:00 0.399 5 3.00 0.66?
0.399 5 1/18/0616:00 0.375 6 2.00 0.500
0.518 2 10/26/06 0:00 0356 7 1.30 0.231
( 0.746 1 1/09/08 6:00 0317 8 1.10 0.091
Computed Peaks 0.670 50.00 0.980
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�fe8`��----_ � '?
+ Till Forest 0.00 acres�
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Till Pasture 0.00 acres�
ITill Grass 0.76 acres
Outwash Forest O.OU acres�'
� Outwash Pasture 0.00 acres�
Outwash Grass� 0.00 acresi
� Wetland U.00 acres�
� Impervious 1.08 acres!
I Total... _.. _.
� 1.84 acres;
_____._..____. .
I Scale Factor : 1.OU Hourly Reduced
Time Series: dev »
Compu#e Time Series L�
� Modify User Input �
,----- - ---____.._---------_...___�.�__.___..._,.--- --_.
� File for computed Time Series [.TSFJ
Flow Frequency Analysis
I Time Series File:dev.tsf
Pro�ect Location:Sea-Tac
J
i I ---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - -Peaks - - Rank Return Prob
(CFS) (CFS) Period
I 0330 6 2/09/�1 2:00 0.671 1 100.00 0.990
� 0.265 8 1/05/0216:00 0.412 2 25.00 0.960
0.397 3 2/27/03 7:00 0.397 3 10.00 0.900
f 0.284 7 8/26/04 2:00 0.350 4 5.00 0.800
� 0.342 5 10/28/0416:00 0.342 S 3.00 0.667
0.350 4 1/18/0616:00 0.330 6 2.00 0.500
I 0.412 2 10/26/06 0:00 0.284 7 1.30 0231
0.671 1 1/09/08 6:00 0.265 8 1.10 0.091
Computed Peaks 0.585 50.00 0.980
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Retention/Detention Facility
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Type of Facility: Detention Vault
� Facility Length: 88. 00 ft
Facility Width: 42.00 ft
Facility Area: 3696.00 sq. ft
Effective Storage Depth: 6.00 ft
I Stage 0 Elevation: 399. 00 ft
Storage Volume: 22176. 00 cu. ft
Riser Head: 6. 00 ft
I Riser Diameter: 12 .00 inches
Number of orifices: 2
Full Head Pipe
Orifice # Height Diameter Discharge Diameter
� (f t) (in) (CFS) {in)
1 0. 00 0.70 0.033
2 4. 10 1.40 0.073 4 .0
� Top Notch Weir: None
Outflow Rating Curve: None
f
----------------------------------
I Route Time Series through Facility
Inflow Time Series File:dev.tsf
Outflow Time Series File:rdout
� Inflow/Outflow Analysis
) Peak Inflow Discharge: 0.671 CFS at 6:00 on Jan 9 in Year 8
Peak Outflow Discharge: �� CFS at 10 :00 on Jan 9 in Year 8 �
1 Peak Reservoir Stage: 6.10 Ft
Peak Reservoir Elev: 405.10 Ft
Peak Reservoir Storage: 22414. Cu-Ft �' 6 �'!� G�
. �. 515 Ac-Ft �`O�
I �V. � 1�0� yr I�V
Flow Frequency Analysis /♦�uv�t`(��
Time Series File:rdout.tsf ` �
Project Location:Sea-Tac
---Annual Peak Flow Rates--- -----Flow Frequency Analysis-------
Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob
I (CFS) (CFS) (ft) Period
� 0. 103 2 2/09/O1 20 :00 0 .4 6 .10 1 100. 00 0.990
0. 024 7 1/07/02 4 :00 0 .103 5.89 2 25.00 0. 960
I 0. 087 3 3/06/03 22 :00 0 .087 5.24 3 10.00 0.900
; 0. 020 8 8/26/04 7 :00 0.082 5 .06 4 5.00 0. 800
� 0.026 6 1/08/05 5 :00 0.045 4 .22 5 3 .00 0.667
0.045 5 1/19/06 2 :00 0.026 3 .72 6 2 .00 0.500
j 0.082 4 11/24/06 B :Oa 0 .024 3 .33 7 1.30 0.231
i 0.410 1 1/09/08 10:00 0 .020 2 . 18 8 1.10 0.091
Computed Peaks 0 .308 6.07 50 .00 0. 980 I
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Bremerton Townhomes October 2012
iTechnical Information Report
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I APPENDIX B
I STORM WATER POLLUTION PREVENTION PLAN
(with appendig' included)
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� Bremerton Townhomes January 2013
� Technical Information Report
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APPENDIX C
STORM WATER POLLUTION PREVENTION PLAN
� (with appendiz' included)
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Stormwater Pollution Prevention Plan
IFor
IBremerton Townhomes
Prepared For
I Washington State Department of Ecology
Northwest Regional Office
3190 - 160th Avenue SE
Bellevue, WA 98008-5452
J 425-649-7000
' Owner Developer Engineer
" Isola Homes LLC Isola Homes LLC Concept Engineering, Inc.
,� 555 S. Renton Village Pl. 555 S. Renton Village Pl. 455 Rainier Blvd. N
� Renton, WA 98059 Renton, WA 98059 Issaquah, WA 98027
�
Project Site Location:
� 320 and 330 Bremerton Ave NE in Renton, WA
Certified Erosion and Sediment Control Lead
� TBD Before Construction
SWPPP Prepared By
� John Abenroth Jr., P.E.
Concept Engineering, Inc.
455 Rainier Blvd. N
� Issaquah, WA 98027
1 SWPPP Preparation Date
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07/19/2012
, Approximate Project Construction Dates
5/01/13-8/Ol/13
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l Contents
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1 1.0 Introduction....................
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2.0 Site Description ........................................................................................................................3
2.1 Existing Conditions...........................................................................................................3
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2.2 Proposed Construction Activities......................................................................................3
3.0 Construction Stormwater BMPs...............................................................................................5
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3.1 The 12 BMP Elements.......................................................................................................5
3.1.1 Element#1 —Mark Clearin�Limits ................................................................5
1 3.1.2 Element#2—Establish Construction Access...................................................5
3.1.3 Element#3 —Control Flow Rates....................................................................5
I 3.1.4 Element #4—Install Sediment Controls..........................................................6
3.1.5 Element #5 —Stabilize Soils............................................................................7
3.1.6 Element#6—Protect Slopes............................................................................8
I 3.1.7 Element#7—Protect Drain Inlets....................................................................9
3.1.8 Element#8— Stabilize Channels and Outlets..................................................9
3.1.9 Element#9—Control Pollutants....................................................................10
I 3.1.10 Element#10— Control Dewaterin�.................................:::.:::.:::.:::.:::.:::.:::::.12
3.1.11 Element#11 —Maintain BMP's............................. .12
3.1.12 Element #12—Mana�e the Project.................................................12
1 3.2 Site Specific BMPs.............................
.............................................................................15
3.3 Additional Advanced BMPs...................:........................................................................15
I4.0 Construction Phasin�and BMP Implementation ...................................................................15
5.0 Pollution Prevention Team ......................................................................................................18
I 5.1 Roles and Responsibilities..........................................................
_ .....................................18
5.2 Team Members................................................................................................................19
l 6.0 Site Inspections and Monitorin�.............................................................................................21
I6.1 Site Ins�ection.. .............................................................................................................21
6.1.1 Site Inspection Frequency..............................................................................21
I 6.1.2 Site Inspection Documentation......................................................................22
6.2 Stormwater Quality Monitoring......................................................................................22
6.2.1 Turbidi ........................................................................................................22
I6.2.2 pH...................................................................................................................23
7.0 Reporting and Recordkeeping ................................................................................................24
� 7.1 Recordkeepin�. ..............................................................................................................24
7.1.1 Site Lo�Book................................................................................................24
7.1.2 Records Retention..........................................................................................24
� 7.1.3 Access to Plans and Records.............................. ...............24
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; 7.1.4 lipdatin�the SWPPP.....................................................................................24
I7.2 Reportin�.........................................................................................................................25
7.2.1 Discharge Monitorin�Reports.......................................................................25
7.2.2 Notification of Noncompliance......................................................................25
_._1 7.2.3 Permit Application and Changes ...................................................................25
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AppendixA—Site Plans.........................................................................................................26
Appendix B—Construction BMPs.........................................................................................27
AQpendix C—Alternative BMPs............................................................................................28
Appendix D—General Permit ................................................................................................31
AQpendix E—Site Inspection Forms (and Site Log)..............................................................32
� Appendix F—Engineering Calculations.................................................................................41
� Appendix A Site plans
� ■ Site plan with TESC measures
Appendix B Construction BMPs
j Appendix C Alternative Construction BMP list
� Appendix D General Permit
Appendix E Site Log and Inspection Forms
( Appendix F Engineering Calculations
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IStormwater Pollution Prevenfion Plan
� 1.0 Introduction
�
� This Stormwater Pollution Prevention Plan (SWPPP) has been prepared as part of the NPDES
stormwater permit requirements for the Bremerton Ave Townhome Plat project in Renton,
I Washington. The site is located just west at 320 & 330 Bremerton Ave, in Renton Washington.
The existing site is a 1.8 acre parcel containing two ta�c parcels (152305-9035 & -9193). The
existing parcel contains two homes, driveways, and garage buildings, all of which will be
� demolished to allow for site development. The development proposes to divide the tax parcel
into a total of 26 lots, along with a road tract, recreation tract, and private drainage tract.
� Construction activities will include demolition, excavation, grading,relocation/extension of
services/utilities, and construction of 415 feet of public street (32 foot wide), and a 42' x 88'
detention vault. The purpose of this SWPPP is to describe the proposed construction activities
I and all temporary and permanent erosion and sediment control (TESC)measures pollution
� prevention measures, inspection/monitoring activities, and recordkeeping that will be
implemented during the proposed construction project. The objectives of the SWPPP are to:
� 1. Implement Best Management Practices (BMPs)to prevent erosion and
sedimentation, and to identify, reduce, eliminate or prevent stormwater
Icontamination and water pollution from construction activity.
1 2. Prevent violations of surface water quality, ground water quality, or
sediment management standards.
( 3. Prevent, during the construction phase, adverse water quality impacts
including impacts on beneficial uses of the receiving water by controlling
peak flow rates and volumes of stormwater runoff at the Permittee's
( outfalls and downstream of the outfalls.
This SWPPP was prepared using the Ecology SWPPP Template downloaded from the Ecology
I website on January 26, 2007. This SWPPP was prepared based on the requirements set forth in
the Construction Stormwater General Permit, Stormwater Management Manual for Western
Washington (SV'J]NaVIWW 2005)and in the Stormwater Management Manual for Eastern
j Washington(SV�NIMEW 2004). The report is divided into seven main sections with several
� appendices that include stormwater related reference materials. The topics presented in the each
of the main sections are:
� ■ Section 1 —INTRODUCTION. This section provides a summary
. description of the project, and the organization of the SWPPP document.
I ■ Section 2— SITE DESCRIPTION. This section provides a detailed
description of the existing site conditions, proposed construction activities,
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� Stormwater Pollution Prevention Plan
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I and calculated stormwater flow rates for existing conditions and post—
construction conditions.
{ ■ Section 3 —CONSTRUCTION BMPs. This section provides a detailed
i description of the BMPs to be implemented based on the 12 required
elements of the SWPPP (SWMIVIEW 2004).
I ■ Section 4—CONSTRUCTION PHASING AIv"D BMP
IlVIPLEMENTATION. This section provides a description of the timing
� of the BMP implementation in relation to the proj ect schedule.
■ Section 5 —POLLUTION PREVENTION TEAM. 'This section identifies
� the appropriate contact names (emergency and non-emergency),
monitoring personnel, and the onsite temporary erosion and sedimentation
I control inspector
� ■ Section 6—INSPECTION AND MONITORING. This section provides a
description of the inspection and monitoring requirements such as the
lparameters of concern to be monitored, sample locations, sample
frequencies, and sampling methods for all stormwater discharge locations
Ifrom the site,
■ Section 7—RECORDKEEPING. This section describes the requirements
� for documentation of the BMP implementation, site inspections,
monitoring results, and changes to the implementation of certain BMPs
due to site factors experienced during construction.
( Supporting documentation and standard forms are provided in the following Appendices:
� I Appendix A— Site plans
Appendix B —Construction BMPs
Appendix C—Alternative Construction BMP list
I Appendix D —General Permit
l Appendix E— Site Log and Inspection Forms
Appendix F—Engineering Calculations
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IStormwater Poflution Prevention Plan
� 2.0 Site Description
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� 2.1 Existing Conditions
IThe proposed site is located at 320 & 330 Bremerton Ave in Renton, Washington. A site
vicinity map and coordinates are provided in Appendix A. The site is 1.84 acres in size and
I includes two existing single-family residences, garages, sheds, and driveways, which will all be
demolished by this project. An outfall to the public storm system was provided at the NE corner
of the site. On-site soils are classified as Alderwood AgC (hyd. Group C).
IThe proposed runoff from the site will discharge into a closed pipe conveyance system that
discharges into the proposed detention vault. From this point, flows discharge towazds the
Inortheast. This stormwater travels several hundred feet in the public storm system, eventually
discharging to a tributary of Maplewood Creek.
JThere are no critical areas on site.
I 2.2 Pro osed Construction Activities
P
The proposed development includes platting of two CA zoned parcels into 26 individual building
lots, road tract, a drainage tract and a recreational tract, and a private stormwater tract. There will
be 415 feet of public street (32 foot wide), and a 42' x 88' detention/treatment vault constructed
Iand a standard piped conveyance system will serve the new lots. New sanitary sewer, water,
electrical and communication utilities will also be constructed.
IConstruction activities will include site preparation, TESC installation, demolition of the existing
house, installation of utilities and stormwater facilities, and asphalt paving. The schedule and
� phasing of BMPs during construction is provided in Section 4.0.
Stormwater runoff volumes were calculated using the King County Runoff Time Senes
� (KCRTS), which is a continuous simulation hydrologic model based on the EPA's HSPF
(Hydrologic Simulation Program-Fortran)program, and is similar to the Western Washington
Hydrology Model ('VVWHM) used by Washington State Department of Ecology. The site of the
I vault may be used as temporary sedimentation trap or the constructed vault may also be used.
The combined detention and water quality vault was designed using (KCRTS).
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Stormwater Pollution Prevention Plan
The following summarizes details regarding site areas:
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Total site area: 1.84 acres
� ■ Percent impervious area before construction: about 5%
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I ■ Percent impervious area after construction: about 60%
■ Disturbed area during construction: 1.84 acres
I ■ Disturbed area that is characterized as impervious (i.e., access
roads, staging, parking): 1.08 acres
I ■ 2-year stormwater runoff peak flow prior to construction
(existing): 0.051 cfs
I ■ 10-year stormwater runoff peak flow prior to construction
(existing): 0.089 cfs
I ■ 2-year stormwater runoff peak flow during construction: 0.330 cfs
( ■ 10-year stormwater runoff peak flow during construction: 0.397 cfs • '
■ 2-year stormwater runoff peak flow after construction: 0.026 cfs
( ■ 10-year stormwater runoff peak flow after construction: 0.087 cfs
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IStormwafer Pollution Prevention Plan
I3.0 Construction Stormwater BMPs
1 3.1 The 12 BMP Elements
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3.1.1 Element#1 —Mark Clearing Limits
` To protect adjacent properties and to reduce the area of soil exposed to construction, the limits of
� construction will be clearly marked before land-disturbing activities begin. Trees that are to be
preserved, as well as all sensitive areas and their buffers, shall be clearly delineated, both in the
( field and on the plans. In general, natural vegetation and native topsoil shall be retained in an
undisturbed state to the maximum extent possible. The BMPs relevant to marking the clearing
limits that will be applied for this project include:
• BMP C 103 - Orange plastic construction fencing and/or high visibility filter
Ifabric fence along all clearing limit edges.
3.1.2 Element#2 —Establish Construction Access
IConstruction access or activities occurring on unpaved areas shall be minimized, yet where
necessary, access points shall be stabilized to minimize the tracking of sediment onto public
Iroads, and wheel washing, street sweeping, and street cleaning shall be employed to prevent
sediment from entering state waters. All wash wastewater shall be controlled on site. The
specific BMPs related to establishing construction access that will be used on this project
include:
I • BMP C 105 Minimum 100' long, 25' wide rock spall construction entrance.
I 3.1.3 Element#3—Control Flow Rates
In order to protect the properties and waterways downstream of the pro�ect site, stormwater
discharges from the site will be controlled. The specific BMPs for flow control that shall be used
I on this project include:
1
• BMP C240 Sediment retention trap. The sediment trap shall be properly sized and
I� maintained regularly. The sediment trap shall be equipped with a properly sized
principal spillway and emergency overflow.
In general, dischazge rates of stormwater from the site will be controlled where increases in
impervious area or soil compaction during construction could lead to downstream erosion, or
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IStormwafer Pollufion Prevenfion Plan
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where necessary to meet local agency stormwater discharge requirements (e.g. discharge to
� combined sewer systems).
� 3.1.4 Element#4—Install Sediment Controls
All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal
� BMP before leaving the construction site or prior to being discharged to an infiltration facility.
I The specific BMPs to be used for controlling sediment on this project include:
! • BMP C240 Sediment retention trap. The sediment trap shall be properly sized and
� maintained regularly. The sediment trap shall be equipped with a properly sized
principal spillway and emergency overflow.
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� • BMP C233 Silt Fence
� • BMP C220 Catch basin insert
Alternate sediment control BMPs are included in Appendix C as a quick reference tool for the
� onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate
during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix
� D}. To avoid potential erosion and sediment control issues that may cause a violation(s) of the
NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and
Sediment Control Lead will promptly mitiate the implementation of one or more of the
( altemative BMI's listed in Appendix C after the first sign that existing BMPs are ineffective or
failing.
I In addition, sediment will be removed from paved areas in and adjacent to construction work
areas manually or using mechanical sweepers, as needed, to minimize tracking of sediments on
vehicle tires away from the site and to minimize washoff of sediments from adjacent streets in
� runoff.
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Whenever possible, sediment laden water shall be discharged into onsite, relatively level,
� vegetated areas (BMP C240 paragraph 5, page 4-102).
In some cases, sediment discharge in concentrated runoff can be controlled using permanent
� stormwater BMPs (e.g., infiltration swales, ponds, and trenches). Sediment loads can limit the
effectiveness of some permanent stormwater BMPs, such as those used for infiltration or
biofiltration; however,those BMPs designed to remove solids by settling (wet ponds or detention
I ponds) can be used during the construction phase. When permanent stormwater BMPs will be
� used to control sediment discharge during construction, the structure will be protected from
excessive sedimentation with adequate erosion and sediment control BMPs. Any accumulated
sediment shall be removed after construction is complete and the permanent stormwater BMP
� will be restabilized with vegetation per applicable design requirements once the remainder of the
� site has been stabilized.
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IStormwater Pollution Prevention Plan
The following BMPs will be implemented as end-of-pipe sediment controls as required to meet
permitted turbidity limits in the site discharge(s). Prior to the implementation of these
technologies, sediment sources and erosion control and soil stabilization BMP efforts will be
� maximized to reduce the need for end-of-pipe sedimentation controls.
■ BMP C240 Temporary Sediment Trap ,
i ■ BMP C251 Construction Stormwater Filtration
I ' BMP C 250 Construction Stormwater Chemical Treatment(implemented
only with prior written approval from Ecology).
I3.1.5 Element #5—Stabilize Soils !
I Exposed and unworked soils shall be stabilized with the application of effective BMPs to prevent
erosion throughout the life of the project. The specific BNIPs for soil stabilization that shall be
used on this project include:
I • BMP C130 Surface roughening on slopes steeper than 3:1 and greater than 5 vertical
feet.
I • BMP C121 Mulching on disturbed areas that require cover measures for less than 30
days, as cover for seed during the wet season and during hot summer months, and
I during the wet season on slopes steeper than 3:1 with more than 10 feet of vertical
relief.
� • BMP C122 Nets and blankets for permanent stabilization of slopes 2:1 or greater and
with more than 10 feet vertical relief. Also in conjunction with side for final
stabilization of slope and for drainage ditches and swales.
I • BMP C123 Plastic covering to provide immediate, short-term erosion protection to
slopes and disturbed areas that require cover measures for less than 30 days.
IParticularly useful for protecting cut and fill slopes and stockpiles. Clear plastic
sheeting may be used over newly seeded areas to create a greenhouse effect and
encourage grass growth.
� BMP C120 Temporary and permanent seeding to stabilize exposed soils. To be used
throughout the project on disturbed areas that have reached final grade or that will
remain unworked for more than 30 days. Vegetation-lined channels and detention
ponds shall also be seeded as required.
IAlternate soil stabilization BNIPs are included in Appendix C as a quick reference tool for the
onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate
� during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix
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IStormwafer Pollution Prevention Plan
� D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the
NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and
Sediment Control Lead will promptly initiate the implementation of one or more of the
-� alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or
failing.
I In genera.l, cut and fill slopes will be stabilized as soon as possible and soil stockpiles will be
temporarily covered with plastic sheeting. All stockpiled soils shall be stabilized from erosion,
protected with sediment trapping measures, and where possible,be located away from storm
Idrain inlets,waterways, and drainage channels.
� 3.1.6 Element#6—Protect Slopes
All cut and fill slopes will be designed, constructed, and protected in a manner than minimizes
I erosion. The following specific BMPs will be used to protect slopes for this project:
I
� BMP C130 Surface roughening on slopes steeper than 3:1 and greater than 5 vertical
I feet.
• BMP C121 Mulching on disturbed areas that require cover measures for less than 30
( days, as cover for seed during the wet season and during hot summer months, and
during the wet season on slopes steeper than 3:1 with more than 10 feet of vertical
relief.
I • BMP C122 Nets and blankets for permanent stabilization of slopes 2:1 or greater and
with more than 10 feet vertical relief. Also in conjunction with side for final
i stabilization of slope and for drainage ditches and swales.
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• BMP C123 Plastic covering to provide immediate, short-term erosion protection to
Islopes and disturbed areas that require cover measures for less than 30 days.
Particularly useful for protecting cut and fill slopes and stockpiles. Clear plastic
� sheeting may be used over newly seeded areas to create a greenhouse effect and
� encourage grass growth.
Alternate slope protection BMPs are included in Appendix C as a quick reference tool for the
� onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate
during construction to satisfy the requirements set forth in the General NPDES Permit(Appendix
D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the
NPDES Construction Stormwater pernut (as provided in Appendix D), the Certified Erosion and
Sediment Control Lead will promptly initiate the implementation of one or more of the
I , alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or
j failing.
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� Sformwafer Po/lution Preventton Plan
I 3.1.7 Element #7—Protect Drain Inlets
All storm drain inlets and culverts made operable dunng construction shall be protected to
prevent unfiltered or untreated water from entering the drainage conveyance system. However,
� the first priority is to keep all access roads clean of sediment and keep street wash water separate
from entering storm drains until treatment can be provided. Storm Drain Inlet Protection (BMP
� C220) will be implemented for all drainage inlets and culverts that could potentially be impacted
by sediment-laden runoff on and near the project site. The following inlet protection measures
will be apphed on ttus pro�ect:
I • BMP C220 Storm Drain inlet Protection:
� 1. Filter fabric protection is filter fabric (geotextile)placed over catch basin grates. This
method requires intense maintenance efforts.
I 2. Catch basin inserts are manufactured devices that nest inside a catch basin.
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3. Block and gravel filters, gravel and wire mesh filter barriers and bag barriers filled with
1 various filtering media can be used to form a barrier around an inlet.
4. Excavated drop inlet sediment traps are appropriate where relatively heavy flows are
expected and overflow capability is needed.
If the BMP options listed above are deemed ineffective or inappropriate during construction to
I satisfy the requirements set forth in the General NPDES Permit (Appendix D), or if no BMPs are
listed above but deemed necessary during construction, the Certified Erosion and Sediment
Control Lead shall implement one or more of the alternative BMP inlet protection options listed
� in Appendix C.
i3.1.8 Element#8— Stabilize Channels and Outlets
Where site runoff is to be conveyed in channels, or discharged to a stream or some other natural
drainage point, efforts will be taken to prevent downstream erosion. The specific BMPs for
channel and outlet stabilization that shall be used on this project include:
j • BMP C201 Vegetation-lined channels and detention ponds shall be seeded as
� required. To be used throughout the proj ect on disturbed areas that have reached final
grade or that will remain unworked for more than 30 days.
• BMP C200 Interceptor Dikes and Swales—A ndge of compacted soil or a swale with
vegetative lining located at the top or base of a sloping disturbed area to intercept
storm water runoff from drainage areas above unprotected slopes and direct it to a
' stabilized outlet.
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I • BMP C207 Check Dams—Small dams constructed across a swale or drainage ditch to
reduce the velocity of concentrated flows, reducing erosion of the swale or ditch, and
to slow water velocity to allow retention of sediments.
1 • BMP C 209 Outlet Protection—Structurally lined aprons or other acceptable energy
dissipating devices placed at the outlet of pipes or paved channel sections to prevent
I scour at stormwater outlets and to minimize the potential for downstream erosion by
reducing the velocity of concentrated stormwater flows.
I Alternate channel and outlet stabilization BMPs are included in Appendix C as a quick reference
� tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or
inappropriate during construction to satisfy the requirements set forth in the General NPDES
1 Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a
� violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the
Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or
Imore of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are
ineffective or failing.
� 3.1.9 Element#9 —Control Pollutants
I All pollutants, including waste matenals and demolition debris, that occur onsite shall be
handled and disposed of in a manner that does not cause contamination of stormwater. Good
housekeeping and preventative measures will be taken to ensure that the site will be kept clean,
1 well organized, and free of debris. If required, BMPs to be implemented to control specific
� sources of pollutants are discussed below.
� • Pesticide Control
1. Pesticides to be disposed of through a licensed waste management firm or
Itreatrnent, storage and disposal company.
2. Use up pesticides, or give away to a garden center, landscape service, etc.
I 3. Containers to be tri le rinsed before dis osa1, reuse rinse water as roduct.
P P p
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I • Petroleum Products
1. Stored in weather-resistant sheds when possible.
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; 2. Create shelter around area with cover and wind protection.
3. Line the storage area with double layer of plastic sheeting or similar material.
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� Stormwater Pollufion Prevention P1an
4. Create impen�ious berm around the perimeter of storage area. Capacity should be
110%of the largest container.
{ 5. All products should be clearly labeled.
�
6. Keep tanks off the ground.
I 7. Keep lids securely fastened.
I8. Contact local fire marshal for more information.
9. Post information for procedures in case of spills. Persons trained in handling
1 spills should be on-site or on call at all times.
10. Materials for cleaning up spills should be kept on-site and easily available. Spills
� should be cleaned up immediately and the contaminated material properly
disposed of.
I1 l. Specify staging area for all vehicle maintenance activities. This area should be
located away from all drainage courses.
l12. All storage sheds, dumpsters or other storage facilities should be regularly
, monitored for leaks and repaired as necessary. Remind workers during
� subcontractor or safety meetings about proper storage and handling of materials.
I • Solid Waste
I1. Provide adequate disposal facilities andlor use authorized disposal areas.
2. Salvage and recycle any useful materials on site.
I3. Adhere to all state and local anti-litter ordinances.
I
• Equipment and Vehicle Washing
� 1. Thinners and solvents should not be discharged into sanitary or storm sewers
I2. Use high-pressure and/or high temperature water washes or steam cleaning if
possible
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Stormwater PoUution P�evention Plan
I 3. Washout from concrete trucks should be disposed of into either; a designated area
which will later be backfilled, an area where the concrete wash can harden, be
broken up and put into a dumpster, or a location which is not subject to surface
� water runoff and more than SOft away from stormwater conveyance systems.
The facility does not require a Spill Prevention, Control, and Countermeasure (SPCC) Plan under
� the Federal regulations of the Clean Water Act (CWA).
I3.1.10 Element#10 —Control Dewatering
All foundation, vault, and trench de-watering water, which have similar characteristics to
� stormwater runoff at the site, shall be discharged into a controlled conveyance system prior to
discharge to a sediment trap or sediment pond. Channels must be stabilized, as specified in
Element #8.
� Clean, non-turbid de-watering water, such as well-point ground water, can be discharged to
systems tributary to state surface waters, as specified in Element#8,provided the de-watering
� flow does not cause erosion or flooding of receiving waters. These clean waters should not be
routed through stormwater sediment ponds.
� Other disposal options, depending on site constraints, may include:
1. Infiltration
2. Transport offsite in a vehicle, such as a vacuum flush truck, for legal disposal in a manner
1 that does not pollute state waters,
3. Ecology-approved on-site chemical treatment or other suitable treatment technologies,
4. Sanitary sewer discharge with local sewer district approval, if there is no other option, or
I 5. Use of a sedimentation bag with outfall to a ditch or swale for small volumes of localized
dewatering.
� 3.1.11 Element#11 —Maintain BMP's
� � All temporary and permanent erosion and sediment control BMPs shall be maintained and
repaired as needed to assure continued performance of their intended function. Maintenance
and repair shall be conducted in accordance with BMP specification.
I • All tem orar erosion and sediment control BMPs shall be removed within 30 da s after
P Y Y
I final site stabilization is achieved or after the temporary BMPs are no longer needed.
Trapped sediment shall be removed or stabilized on site. Disturbed soil resulting from
removal of BMPs or vegetation shall be permanently stabilized.
I3.1.12 Element#12—Manage the Project
I • Phasing of Construction.
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Storrnwater Po!lufion Prevention Plan
Development projects shall be phased where feasible in order to prevent soil erosion and, to
the maximum extent practicable, the transport of sediment from the site during construction.
Revegetation of exposed areas and maintenance of that vegetation shall be an integral part of
{ the clearing activities for any phase.
1
Clearing and grading activities for developments shall be permitted if conducted pursuant to
I an approved site development plan(e,g., subdivision approval) that establishes permitted
areas of clearing, cutting, and filling. When establishing these pernutted clearing and
grading areas, consideration should be given to minimizing removal of existing trees and
I minimizing disturbance/compaction of the native soils except as needed for building
oses. These ernutted clearin and adin areas and an other areas re uired to
P�P P g � g Y q
preserve critical or sensitive areas,buffers, native growth protection easements, or tree
1 retention areas as may be required by local jurisdictions, shall be delineated on the site plans
and the development site.
� � Seasonal Work Limitations
I
From October 1 through April 30, clearing, grading, and other soil disturbing activities shall
Ionly be permitted if shown to the satisfaction of the local permitting authority that silt laden
runoff will be prevented from leaving the site through a combination of the following: ,
I1. Site conditions including existing vegetarive coverage, slope, soil type, and proximity to
receiving waters; and
� 2. Limitations on activities and the extent of disturbed areas; and
` 3. Proposed erosion and sediment control measures.
i
Based on the information provided and/or local weather conditions, the local permitting
i authority may expand or restrict the seasonal limitation on site disturbance. The local
� permitting authority shall take enforcement action—such as a notice of violation,
administrative order, penalty, or stop-work order under the following circumstances:
- If, during the course of any construction activity or soil disturbance during the seasonal
limitation period, sediment leaves the construction site causing a violation of the surface
i water quality standard; or
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- If clearing and grading limits or erosion and sediment control measures shown in the
approved plan are not maintained.
The following activities are exempt from the seasonal clearing and grading limitations:
� 1. Routine maintenance and necessary repair of erosion and sediment control BMPs;
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( Stormwafer Pollution Prevenfion Plan
2. Routine maintenance of public facilities or existing utility structures that do not expose
the soil or result in the removal of the vegetative cover to soil; and
� 3. Activities where there is one hundred percent infiltration of surface water runoff within
the site in approved and installed erosion and sediment control facilities.
I • Coordination with Utilities and Other Contractors '
The primary project proponent shall evaluate, with input from utilities and other contractors,
I the stormwater management requirements for the entire proj ect, including the utilities, when
preparing the construction SWPPP.
� • Inspection and Monitoring
All BMPs shall be inspected, maintained, and repaired as needed to assure continued '�
Iperformance of their intended function. Site inspections shall be conducted by a person who I
is lrnowledgeable in the principals and practices of erosion and sediment control. The person I
must have the skills to 1) assess the site conditions and construction activities that could
Iimpact the quality of stormwater, and 2) assess the effectiveness of erosion and sediment
control measures used to control the quality of stormwater dischazges.
IFor construction sites one acre or larger that discharge stormwater to surface waters of the
state, A certified Erosion and Sediment Control Specialist shall be identified in the
I Construction SWPPP and shall be on-site or on-call at all times. Certification may be
obtained through the approved training program that meets the erosion and sediment control
training standards established by Ecology.
lWhenever Inspection and/or monitoring reveals that the BMPs identified in the Construction
SWPPP are inadequate, due to the actual discharge of or potential to discharge a significant
I amount of any pollutant, appropriate BMPs vr design changes shall be implemented as soon
as possible.
( • Maintaining an Updated Construction SWPPP
The Construction SWPPP shall be retained on-site or within reasonable access to the site.
� The SWPPP shall be modified whenever there is a change in the design. Construction,
operation, or maintenance at the construction site that has, or could have, a significant effect
+ on the discharge of pollutants to waters of the state.
�
The SWPPP shall be modified if, during inspections or investigations conducted by the
Iowner/operator, or the applicable local or state regulatory authority, it is determined that the
SWPPP is ineffective in eliminating or significantly minimizing pollutants in stormwater
Idischarges from the site. The SWPPP shall be modified as necessary to include additional or
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Stormwater Pollution Prevention PJan
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I modified BMPs designed to correct problems identified. Revisions to the S WPPP shall be
� completed within seven(7) days following the inspection.
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' 3.2 Site Specific BMPs �
Site specific BMPs are shown on the TESC Plan Sheets and Details in Appendix A. These site I
Ispecific plan sheets will be updated annually.
-1
i 3.3 Additional Advanced BMPs
�
No additional advanced BMPs are anticipated at this time. If need arises,design and installation
( will be coordinated with the local jurisdiction.
I
4.0 Construction Phasing and BMP
` Implementation
I The BMP implementation schedule will be driven by the construction schedule. The following
provides a sequential list of the proposed construction schedule milestones and the corresponding
BMP implementation schedule. The list contains key milestones such as wet season
� construction.
I ■ Mobilize equipment on site:
■ Mobilize and store all ESC and soil stabilization products:
■ Install ESC measures:
■ Install stabilized construction entrance:
■ Begin elearing and grubbing:
■ Remove existing structures:
■ Install drainage system downstrearn of vault:
� ■ Install detention/water quality vault system:
' ■ InstalUconstruct water & sewer urilities:
I ■ Install on-site storm drainage system with catch basin inlet protection
i ■ Install pavement and landscaping
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■ Maintain, install and/or relocate erosion control measures as needed ''
' • Clean and flush stormdrain system, remove sediments from vault and ��
stabilize all disturbed areas
--� ■ Remove all TESC components when the site is stabilized and approval is
received from the clearing and grading inspector.
I
I BMP implementation schedule listed below is keyed to proposed phases of the construction
project, and reflects differences in BMP installations and inspections that relate to wet season
E construction. All site work is intended to be completed during the dry season. The dry season is
considered to be from May 1 to September 30 and the wet season is considered to be from I,
October 1 to April 30.
—f
I ■ Estimate of Construction start date: OS / 15 /2013 I
■ Estimate of Construction finish date: 8 / 30/2013
�
� ■ Mobilize equipment on site: OS / 15 /2013
� ■ Mobilize and store all ESC and soil stabilization products
I (store materials on hand BMP C150): OS / 15 / 2013
I ■ Install ESC measures: OS / 16 /2013
I
■ Install stabilized construction entrance: OS / 17 /2013
I ■ Begin clearing and grubbing: OS /20/2013
■ Demolish existing one-story building structure: OS /20/2013
■ Site grading begins: OS /22/2013
' ' Soil stabilization on excavated sideslopes (in idle, no
work azeas as shown on ESC plans) OS /29 /2013
, ■ Temporary erosion control measures (hydroseeding) OS / 29 /2013
�
� ■ Site inspections reduced to monthly: OS /29 /2013
I
' ■ Excavate and install new utilities and services: 06 /03 /2013
j
� ■ Final landscaping and planting begins: 7 /O1 /2013
, ■ Permanent erosion control measures: 7 / O1 / 2013
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Sformwater Po!lution Prevention Plan
i ■ Begin implementing soil stabilization and sediment '!
Icontrol BMPs throughout the site in preparation for wet '
season(if necessa.ry): 7 / O1 / 2013
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Stormwater Pollution Prevenfion Plan '
� 5.0 Pollution Prevention Team
�
� 5.1 Roles and Responsibilities I,
The pollution prevention team consists of personnel responsible for implementation of the I�
I SWPPP, mcluding the following: I
l ■ Certified Erosion and Sedunent Control Lead(CESCL)—primary . I,
contractor contact, responsible for site inspections (BNIPs, visual
monitoring, sampling, etc.); to be called upon in case of failure of any j
IESC measures. ',
■ Resident Engineer—For proj ects with engineered structures only
(sediment ponds/traps, sand filters, etc.): site representative for the owner
that is the project's supervising engineer responsible for inspections and
I issuing instructions and drawings to the contractor's site supervisor or
representative
i ■ Emergency Ecology Contact—individual to be contacted at Ecology in
case of emergency.
I ■ Emergency Owner Contact—individual that is the site owner or
representative of the site owner to be contacted in the case of an
emergency.
1 ■ Non-Emergency Ecology Contact—individual that is the site owner or
representative of the site owner than can be contacted if required.
I ■ Monitoring Personnel—personnel responsible for conducting water
quality monitoring; for most sites this person is also the Certified Erosion
Iand Sediment Control Lead.
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Stormwater Pollution Prevention Plan
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i 5.2 Team Members
I Names and contact information for those identified as members of the pollution prevention team
aze provided in the following table.
( Title Name(s) Phone Number �
Certified Erosion and Sediment Control Lead(CESCL) TBD TBD
I Resident Engineer Barry Constant,PE (425)392-8055
Emergency Ecology Contact Spills: Paul O'Bnen (425)649-7130
Toxics Cleanup: Steven Alexander (425)649-7054
� Water Quality: Kevin Fitzpatrick (425)649-7033
Puget Sound Field Office(spills only) (206)389-2431
IEmergency Owner Contact Greg Boehme (425)282-0435
Non-Emergency Ecology Contact Water Quality: Kevin Fitzpatrick (425)649-7033
IMonitoring Personnel TBD
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, 6.0 Site Inspections and Monitoring
I
� Monitoring includes visual inspection,monitoring for water quality parameters of concern, and
documentarion of the inspection and monitoring findings in a site logbook. A site logbook will
be maintained for all on-site construction activities and will include:
I ■ A record of the implementation of the SWPPP and other permit
requirements;
I ■ Site inspections; and,
I ■ Stormwater quality monitoring.
For convenience, the inspection form and water quality monitoring forms included in this
I SWPPP include the required information for the site logbook. This SWPPP may function as the
� site logbook if desired, or the forms may be separated and included in a separate site logbook.
However, if separated, the site logbook but must be maintained on-site or within reasonable
Iaccess to the site and be made available upon request to Ecology or the local jurisdiction.
6.1 Site Inspection
l All BMPs will be inspected, maintained, and repaired as needed to assure continued performance
� of their intended function. The inspector will be a Certified Erosion and Sediment Control Lead
(CESCL)per BMP C160. The name and contact information for the CESCL is provided in
ISection 5 of this SWPPP.
Site inspection will occur in all areas disturbed by construction activities and at all stormwater
I discharge points. Stormwater will be examined for the presence of suspended sediment,
turbidity, discoloration, and oily sheen. The site inspector will evaluate and document the
effectiveness of the installed BMPs and determine if it is necessary to repair or replace any of the
I BMPs to improve the quality of stormwater discharges. All maintenance and repairs will be
� documented in the site log book or forms provided in this document. All new BMPs or design
Ichanges will be documented in the SWPPP as soon as possible.
6.1.1 Site Inspection Frequency
Site inspections will be conducted at least once a week and within 24 hours following any
rainfall event which causes a discharge of stormwater from the site. For sites with temporary
stabilization measures, the site inspection frequency can be reduced to once every month.
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IStormwater Pollution Prevention Plan
� 6.1.2 Site Inspection Documentation
� The site inspector will record each site inspection using the site log inspection forms provided in
�
Appendix E. The site inspection log forms may be separated from this SWPPP document, but
� will be maintained on-site or within reasonable access to the site and be made available upon
request to Ecology or the local jurisdiction.
�
I 6.2 Stormwater Quality Monitoring
I
6.2.1 Turbidity
} Turbidity sampling and monitoring will be conducted during the entire construction phase of the
project. Samples will be collected daily at the catch basin located just offsite at the northeast
comer of the project. If there is no flow in this catch basin, the attempt to sample will be
recorded in the site logbook and reported to Ecology in the monthly Discharge Monitoring
Report (DMR) as "No Discharge". Samples will be analyzed for turbidity using the EPA 180.1
} analytical method.
�
The key benchmark turbidity value is 25 nephelometric turbidity units (NT� for the
� downstream receiving water body. If the 25 NTU benchmark is exceeded in any sample
collected from CBS, the following steps will be conducted:
I 1. Ensure all BMPs specified in this SWPPP are installed and functioning as
intended.
I 2. Assess whether additional BMPs should be implemented, and document
� modified BMPs in the SWPPP as necessary.
I3. Sample discharge daily until the discharge is 25 NTU or lower.
If the turbidity exceeds 250 NTU at any time, the following steps will be conducted:
1. Notify Ecology by phone within 24 hours of analysis (see Section 5.0 of ,
this SWPPP for contact information). �
' 2. Continue sampling daily until the dischazge is 25 NTLJ or lower. Initiate
� additional treatment BMPs such as off-site treatment, infiltration, filtration
and chemical treatment within 24 hours, and implement those additional
treatrnent BMPs as soon as possible, but within a minimum of 7 days.
� 3. Describe inspection results and remedial actions taken in the site logbook II
and in monthly discharge monitoring reports as described in Section 7.0 of
I this SWPPP.
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ISampling and morlltonng for pH will occur dunng the phase ot construction when concrete
'� pouring will be conducted until fully cured (3 weeks from pour). Samples will be collected
� weekly at the sedimentation pond prior to discharge to surface water. Samples will be anal��zed
for pH using a calibrated pH meter and recorded in the site logbook.
The key benchmark pH value for stormwater is a maximum of 8.0. If a pH greater than 8.0 is
measured in the sedimentation pond tl�at has the potential to discharge to surface water, the
Ifollowing steps will be conducted:
1. Assess whether additional BMPs should be implemented and whether
associated revisions to the SWPPP are necessary. ''�
�I
2. Stop (detain) all discharges from leaving the site and entering surface ',
� waters or storm drains if the pH is greater than 8.5. ''�,
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3. Sample sedimentation pond the following day, and if the pH exceeds 8.0 '
� for the second consecutive day, implement CO2 sparging treatment. �,
4. Sample and measure pH daily until there are 3 consecutive pH
� measurements less than 8.0.
5. If there are 3 consecutive pH measurements greater than 8.0, notify
i Ecology by phone within 24 hours of the 3rd measurement exceeding a pH
of 8.0 (see Section 5.0 of this SWPPP for contact information) and initiate
discussions with Ecology regarding additional treatment BMPs.
� 6. Describe inspection results and remedial actions that are taken in the site
log book and in monthly dischaxge monitoring reports as described in
Section 7.0 of this SWPPP.
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I 7.0 Reporting and Recordkeeping
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7.1 Recordkeeping
I
' 7.1.1 Site Log Book
( A site logbook will be maintained for all on-site construction activities and will include:
' A record of the implementation of the SWPPP and other permit ,
i requirements;
f
■ Site inspections; and,
■ Stormwater quality monitoring.
lFor convenience, the inspection form and water quality monitoring forms included in this
SWPPP include the required information for the site logbook.
� 7.1.2 Records Retention
I Records of all monitoring information(site log book, inspection reports/checklists, etc.),this
Stormwater Pollution Prevention Plan, and any other documentation of compliance with pernut
requirements will be retained during the life of the construction proj ect and for a minimum of
three years following the ternunation of permit coverage in accordance with permit condition
SS.C.
�
� 7.1.3 Access to Plans and Records
� The SWPPP, General Permit,Notice of Authorization letter, and Site Log Book will be retained
; on site or within reasonable access to the site and will be made immediately available upon
request to Ecology or the local jurisdiction. A copy of this SWPPP will be provided to Ecology
within 14 days of receipt of a written request for the SWPPP from Ecology. Any other
information requested by Ecology will be submitted within a reasonable time. A copy of the
SWPPP or access to the SWPPP will be provided to the public when requested in writing in
accordance with permit condition SS.G.
! 7.1.4 Updating the SWPPP
;
In accordance with Conditions S3, S4.B, and S9.B.3 of the General Permit, this SWPPP will be
modified if the S WPPP is ineffective in eliminating or significantly minimizing pollutants in
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i Stormwater Pollution Prevenfion Plan
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stormwater discharges from the site or there has been a change in design, construction, operation,
or maintenance at the site that has a significant effect on the discharge, or potential for discharge,
of pollutants to the waters of the State. The SWPPP will be modified within seven days of '
� determination based on inspection(s) that additional or modified BMPs are necessary to correct
, problems identified, and an updated timeline for BMP implementation will be prepared.
�
'' 7.2 Reporting
7.2.1 Discharge Monitoring Reports
Discharge Monitoring Report (DMR) forms will not be submitted to Ecology because water
� quality sampling is not being conducted at the site.
�
� 7.2.2 Notification of Noncompliance
1 If any of the terms and conditions of the permit aze not met, and it causes a threat to human
health or the environment, the following steps will be taken in accordance with permit section
SS.F:
!
� 1. Ecology will be immediately notified of the failure to comply.
1 2. Immediate action will be taken to control the noncompliance issue and to
' correct the problem. If applicable, sampling and analysis of any
I noncompliance will be repeated immediately and the results submitted to
Ecology within five (5) days of becoming aware of the violation.
I 3. A detailed written report describing the noncompliance will be submitted
� to Ecology within five (5) days, unless requested earlier by Ecology.
I In accordance with permit condition S2.A, a complete application form will be submitted to
� Ecology and the appropriate local jurisdiction (if applicable)to be covered by the General
Permit.
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; Stormwater Po!lution Prevention Plan
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; Appendix A — Site Plans
� SEE 24" x 36" SITE DEVELOPMENT PLANS
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iSformwater Po!lution Prevention Plan
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� Appendix B — Construction BMPs
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' BMP C103: High Visibility Plastic or Metal Fence
� Purpose Fencing is intended to: (1)restrict clearing to approved limits; (2) prevent
� disturbance of sensitive areas, theu buffers, and other areas required to be
left undisturbed; (3) limit construction traffic to designated construction
�j entrances or roads; and, (4)protect areas where marking with survey tape
� may not provide adequate protection.
Conditions of Use To establish clearing limits, plastic or metal fence may be used:
• At the boundary of sensitive areas, their buffers, and other areas
required to be left uncleared.
• As necessary to control vehicle access to and on the site.
� Design and • High visibility plastic fence shall be composed of a high-density
Installation polyethylene material and shall be at least four feet in height. Posts
Specif:cations for the fencing shall be steel or wood and placed every 6 feet on
I center(maximum) or as needed to ensure rigidity. The fencing shall
be fastened to the post every six inches with a polyethylene tie. On
long continuous lengths of fencing, a tension wire or rope shall be
I used as a top stringer to prevent saggi.ng between posts. The fence
color shall be high visibility orange. The fence tensile strength shall
be 3b0 lbs./ft. using the ASTM D4595 testing method.
I • Metal fences shall be designed and installed according to the
manufacturer's specifications.
1 • Metal fences shall be at least 3 feet high and must be highly visible.
' • Fences shall not be wired or stapled to trees.
� Maintenance • If the fence has been damaged or visibility reduced, it shall be
Standards repaired or replaced immediately and visibility restored.
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IBMP C105: Stabilized Construction Entrance
1 Purpose Construction entrances are stabilized to reduce the amount of sediment
` transported onto paved roads by vehicles or equipment by constructing a
stabilized pad of quarry spalls at entrances to construction sites.
� Conditions of Use Construction entrances shall be stabilized wherever traffic will be leaving
' a construction site and traveling on paved roads or other paved areas
within 1,000 feet of the site.
IOn large commercial, highway, anci road projects, the designer should
include enough extra materials in the contract to allow for additional
I stabilized entrances not shown in the initial Construction SWPPP. It is
diff'icult to determine exactly where access to these projects will take_
place; additional materials will enable the contractor to install them where
I needed.
Design and • See Figure 4.2 for details. Note: the 100' minimum length of the
Installation entrance shall be reduced to the maximum practicable size when the
ISpecifications size or configuration of the site does not allow the full length (100').
• A se aration eotextile shall be laced under the s alls to revent
P P P P
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fine sediment from pumping up into the rock pad. The geotextile
� l shall meet the following standards:
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� Grab Tensile Strength(ASTM D4751) 200 psi min.
I� ` Grab Tensile Elongation (ASTM D4632) 30% max.
Mullen Burst Strength (ASTM D3786-80a) 400 psi min.
� � AOS (ASTM D4751) 20-45 (U.S. standard sieve size)
• Consider early installation of the first lift of asphalt in areas that will
� paved; this can be used as a stabilized entrance. Also consider the
installation of excess concrete as a stabilized entrance. During large
concrete pours, excess concrete is often available for this purpose.
I • Hog fuel (wood-based mulch) may be substituted for or combined with
quarry spalls in areas that will not be used for permanent roads. Hog
I fuel is generally less effective at stabilizing construction entrances and
should be used only at sites where the amount of traffic is very limited.
Hog fuel is not recommended for entrance stabilization in urban areas.
� The effectiveness of hog fuel is highly variable and it generally
requires more maintenance than quarry spalls. The inspector may at
any time require the use of quarry spalls if the hog fuel is not
� preventing sediment from being tracked onto pavement or if the hog
fuel is being carried onto pavement. Hog fuel is prohibited in
permanent roadbeds because organics in the subgrade soils cause
degradation of the subgrade support over time.
• Fencing(see BMPs C 103 and C 104) shall be installed as necessary to
restrict traffic to the construction entrance.
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• Whenever possible, the entrance shall be constructed on a firm,
compacted subgrade. This can substantially increase the effectiveness
Iof the pad and reduce the need for maintenance.
Maintenance • Quarry spalls (or hog fuel) shall be added if the pad is no longer in
� Standards accordance with the specifications.
• If the entrance is not preventing sediment from being tracked onto
pavement, then altemative measures to keep the streets free of
lsediment shall be used. This may include street sweeping, an increase
, in the dir�ensions of the entrance, or the installation of a wheel wash.
• Any sediment that is tracked onto pavement shall be removed by
I shoveling or street sweeping. The sediment collected by sweeping
shall be removed or stabilized on site. The pavement shall not be
cleaned by washing down the street, except when sweeping is
I ineffective and there is a threat to public safety. If it is necessary to
wash the streets, the construction of a small sump shall be considered.
The sediment would then be washed into the sump where it can be
Icontrolled.
• Any quarry spalls that are loosened from tfie pad, which end up on the
I roadway shall be removed immediately.
• If vehicles are entering or exiting the site at points other than the
construction entrance(s), fencing (see BMPs C 103 and C 104) shall be
I installed to control traffic.
• Upon project completion and site stabilization, all construction
accesses intended as permanent access for maintenance shall be
� ermanentl stabilized.
Driveway shall meel the
requiramenis of[he
( permitting apency
It is racommended ihal
the entrance he
crowned so that runoH
� � �� drains oft Ihe pad
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tiy;�st�P i
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Install d�lveway culvert
I N Ihere Is a roaCside
ditch present
4'-8'quarry spa�ls
Geoleztlle
�`o. ,�(\�t�
I `h �
12'min.ldkJcness_� 1�
Provide lull width o'
Ingresslegrass area
Figure 4.2—Stabilized Construction Entrance
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BMP C120: Temporary and Permanent Seeding
l Purpose Seeding is intended to reduce erosion by stabilizing exposed soils. A
well-established vegetative cover is one of the most effective methods of
reducing erosion.
� Conditions of Use ' Seeding may be used throughout the project on disturbed areas that
have reached final grade or that will remain unworked for more than
I 30 days.
• Channels that will be vegetated should be installed before maj or
earthwork and hydroseeded with a Bonded Fiber Matrix. The
I vegetation should be well established (i.e., 75 percent cover)before
water is allowed to flow in the ditch. With channels that will have
high flows, erosion control blankets should be installed over the
fhydroseed. If vegetation cannot be established from seed before water
� is allowed in the ditch, sod should be installed in the bottom of the
ditch over hydromulch and blankets.
I • Retention/detention ponds should be seeded as required.
• Mulch is required at all times because it protects seeds from heat,
Imoisture loss, and transport due to runoff.
• All disturbed areas shall be reviewed in late August to early September
I and all seeding should be completed by the end of September.
Otherwise, vegetation will not establish itself enough to provide more
than average protection.
� • At fmal site stabilization, all disturbed areas not otherwise vegetated or
stabilized shall be seeded and mulched. Final stabilization means the
I completion of all soil disturbing activities at the site and the
establishment of a permanent vegetative cover, or equivalent
permanent stabilization measures (such as pavement, nprap, gab�ons
( or geotextiles) which will prevent erosion.
Design and • Seeding should be done during those seasons most conducive to
Installation gi'owth and will vary with the climate conditions of the region.
I Specifications Local experience should be used to determine the appropriate
seeding periods.
I • The optimum seeding windows for westem Washington are April 1
through June 30 and September 1 through October 1. Seeding that
occurs between July 1 and August 30 will require irngation until 75
I percent grass cover is established. Seeding that occurs between
October 1 and March 30 will require a mulch or plastic cover until
75 percent grass cover is established.
I • To prevent seed from being washed away, confirm that all required
� surface water control measures have been installed.
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� • The seedbed should be firm and rough. All soil should be roughened
no matter what the slope. If compaction is required for engineering
I purposes, slopes must be track wa]ked before seeding. Backblading or
smoothing of slopes greater than 4:1 is not allowed if they are to be
seeded.
� • New and more effective restoration-based landscape practices rely on
deeper incorporation than that provided by a simple single-pass
I rototilling treatment. Wherever practical the subgrade should be
initially ripped to improve long-term permeability, infiltration, and
water inflow qualities. At a minimum,permanent areas shall use soil
I amendments to achieve organic matter and permeability performance
defined in engineered soiUlandscape systems. For systems that are
deeper than 8 inches the rototilling process should be done in multiple
I lifts, or the prepared soil system shall be prepared properly and then
placed to achieve the specified depth.
� • Organic matter is the most appropriate form of"fertilizer" because it
provides nutrients (including nitrogen, phosphonis, and potassium) in
the least water-soluble form. A natural system typically releases 2-10
I percent of its nutrients annually. Chemical fertilizers have since been
formulated to simulate what organic matter does naturally.
• In general, 10-4-6 N-P-K(nitrogen-phosphorus-potassium) fertilizer
I can be used at a rate of 90 pounds per acre. Slow-release fertilizers
should always be used because they are more efficient and have fewer
environmental impacts: It is recommended that areas being seeded for
1 fmal landscaping conduct soil tests to determine the exact type and
quantity of fertilizer needed. This will prevent tYie over-application of
fertilizer. Fertilizer should not be added to the hydromulch machine
I and agitated more than 20 minutes before it is to be used. If agitated
� too much, the slow-release coating is destroyed.
I • There are numerous products available on the market that take the
place of chemical fertilizers. These include several with seaweed
extracts that are beneficial to soil microbes and organisms. If 100
I percent cottonseed meal is used as the mulch in hydroseed, chemical
fertilizer may not be necessary. Cottonseed meal is a good source of
long-term, slow-release, available nitrogen.
� • Hydroseed applications shall include a minimum of 1,500 pounds per
acre of mulch with 3 percent tackifier. Mulch may be made up of 100
percent: cottonseed meal; fibers made of wood, recycled cellulose,
� hemp, and kenaf; compost; or blends of these. Tackifier shall be plant-
based, such as guar or alpha plantago, or chemical-based such as
� polyacrylamide or polymers. Any mulch or tackifier product used
shall be installed per manufacturer's instructions. Generally, mulches
come m 40-50 pound bags. Seed and fertilizer are added at time of
application.
� 4-14 Volume 11—Construcfion Stormwater Pollutron Prevenfion February 2005
( • Mulch is always required for seeding. Mulch can be applied on top of
the seed or simultaneously by hydroseeding.
� • On steep slopes, Bonded Fiber Matrix (BFM) or Mechanically Bonded
Fiber Matrix MBF roducts should be used. BFMIMBFM
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_ products are applied at a minimum rate of 3,000 pounds per acre of
� mulch with approximately 10 percent tackifier. Application is made
so that a minimum of 95 percent soil coverage is achieved. Numerous
I products are available commercially and should be installed per
manufacturer's instructions. Most products require 24-36 hours to
cure before a ramfall and cannot be installed on wet or saturated soils.
Generally,these products come in 40-50 pound bags and include all
necessary ingredients except for seed and fertilizer.
� BFMs and MBFMs have some advantages over blankets:
� • No surface preparation required;
I • Can be installed via helicopter in remote areas;
� • On slopes steeper than 2.5:1, blanket installers may need to be roped
and hamessed for safety;
� • They are at least $1,000 per acre cheaper installed.
I In most cases, the shear strength of blankets is not a factor when used on
� slopes, only when used in channels. BFMs and MBFMs are good
alternatives to blankets m most situations where vegetation establishment
� is the goal.
• When installing seed via hydroseeding operations, only about 1/3 of
the seed actually ends up in contact with the soil surface. This reduces
the ability to esta.blish a good stand of grass quickly. One way to
overcome this is to increase seed quantities by up to 50 percent.
• Vegetation establishment can also be enhanced by dividing the
hydromulch operation into two phases:
1. Phase 1-Install all seed and fertilizer with 25-30 percent mulch
Iand tackifier onto soil in the first lift;
2. Phase 2- Install the rest of the mulch and tackifier over the first lift.
i An altemative is to install the mulch, seed, fertilizer, and tackifier in one
� lift. Then, spread or blow straw over the top of the hydromulch at a rate of
i about 800-1000 pounds per acre. Hold straw in place with a standard ;
tackifier. Both of these approaches will increase cost moderately but will �
greatly improve and enhance vegetative establishment. The increased cost
may be offset by the reduced need for:
j 1. Irrigation
2. Reapplication of mulch
I 3. Repair of failed slope surfaces
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� This technique works with standard hydromulch (1,500 pounds per acre
minimum) and BFM/MBFMs (3,000 pounds per acre minimum).
• Areas to be permanently landscaped shall provide a healthy topsoil
that reduces the need for fertilizers, improves overall topsoil quality,
� provides for better vegetal health and vitality, improves hydrologic
characteristics, and reduces the need for irrigation. This can be
accomplished in a number of ways:
� Recent research has shown that the best method to improve till soils is
to amend these soils with compost. The optimum mixture is
I approximately two parts soil to one part compost. T'his equates to 4
inches of compost mixed to a depth of 12 inches in till soils. Increasing
the concentration of compost beyond this level can have negative
� effects on vegeta.l health, while decreasing the concentrations can
reduce the benefits of amended soils. Please note: The compost should
meet specifications for Grade A quality compost in Ecology
lPublication 94-038.
Other soils, such as gravel or cobble outwash soils, may require
� different approaches. Organics and fines easily migrate through the
loose structure of these soils. Therefore, the importation of at least 6
inches of qua.lity topsoil,underlain by some type of filter fabric to
� prevent the migration of fines, may be more appropriate for these soils.
Areas that already have good topsoil, such as undisturbed areas, do not
� require soil amendments.
• Areas that will be seeded only and not landscaped may need compost
� or meal-based mulch included in the hydroseed in order to establish
vegetation. Native topsoil should be re-installed on the disturbed soil
surface before application.
� • Seed that is installed as a temporary measure may be insta.11ed by hand
if it will be covered by straw, mulch, or topsoil. Seed that is installed
� as a permanent measure may be installed by hand on small areas
(usually less tha.n 1 acre) that will be covered with mulch, topsoil, or
erosion blankets. The seed mixes listed below include recommended
! mixes for both temporary and permanent seeding. These mixes, with
{ the exception of the wetland mix, shall be applied at a rate of 120
pounds per acre. This rate can be reduced if soil amendments or slow-
i release fertilizers are used. Local suppliers or the local conservation
f district should be consulted for their recommendations because the
appropriate mix depends on a variety of factors, including location,
� exposure, soil type, slope, and expected foot traffic. Altemative seed
mixes approved by the local authority may be used.
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ITable 4.1 represents the standard mix for those areas where just a
temporary vegetative cover is required.
� Table 4.1
Tem ora Erosion Control Seed Mix
°/a Wei ht %Puri °/a Germination
Chewings or annual blue grass 40 98 90
I � Festuca rubra var. commutata or Poa anna
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Perennial rye- 50 98 90
( Lolium erenne
Redtop or colonial bentgrass 5 92 85
A rostis alba or A ostis tenuis
I White dutch clover 5 98 90
Tri olium r ens
Table 4.2 provides just one recommended possibility for landscaping seed.
� Table 4.2
Landsca in Seed Mix
%Wei ht %Puri % Germination
� Perennial rye blend 70 98 90
� Lolium erenne
Chewings and red fescue blend 30 98 90
I Festuca rubra var. commutata
or Festuca rubra
This turf seed mix in Table 4.3 is for dry situations where there is no need
` for much water. The advantage is that this mix requires very little
� maintenance.
� Table 4.3
Low-Growin Turf Seed Mix
% Wei ht %Puri %Germination
Dwarf tall fescue(several varieties) 45 98 90
Festuca arundinacea var.
Dwarf perennial rye(Bazclay) 30 98 90
Lolium erenne var. barcl
I Red fescue 20 98 90
� Festuca rubra
Colonial bentgrass 5 98 90
A ostis tenuis
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i Table 4.4 presents a mix recommended for bioswales and other
intermittently wet areas.
ITable 4.4
Bioswale Seed Mix'
°/a Wei ht %Purit %Germination
Tall or meadow fescue 75-80 98 90
Festuca arundinacea or Festuca elatior
Seaside/Creeping bentgrass 10-15 92 85
� A ostis alustris
Redtop bentgrass 5-10 90 80
' A ostis alba or A oslis ' antea
*Modified Briargreen, Inc.Hydroseeding Guide Wetlands Seed M'ix
', February 2005 Volume !!— Construction Sformwater Pollution Prevention 4-17
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IThe seed mix shown in Table 4.5 is a recommended low-growing,
relatively non-invasive seed mix appropriate for very wet areas that are
Inot regulated wetlands. Other mixes may be appropriate, depending on
the soil type and hydrology of the area. Recent research suggests that
bentgrass (agrostis sp.) should be emphasized in wet-area seed mixes.
� Apply this mixture at a rate of 60 pounds per acre.
Table 4.5
! Wet Area Seed Mix•
I °/a Wei ht %Puri °/a Germination
Tall or meadow fescue 60-70 98 90
i Festuca arundinacea or
` Festuca elatior
Seaside/Creeping bentgrass 10-15 98 85
_� A ostis alustris
Meadow foxtail 10-15 90 80
Ale ocurus ratensis
Alsike clover 1-6 98 90
� Tri olium h bridum
Redtop bentgrass 1-6 92 85
A ostis alba
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I *Mod�ed Briargreen,Inc. Hydroseeding Guide Wetlands Seed M'zx
The meadow seed mix in Table 4.6 is recommended for area� that ��i l l be
maintained infrequently or not at all and where colonization by native
� plants is desirable. Likely applications include rural road and utility right-
of-way. Seeding should take place in September or very early October in
order to obtain adequate establishment prior to the winter months. The
` appropriateness of clover in the mix may need to be considered, as this can
� be a fauly invasive species. If the soil is amended, the addition of clover
may not be necessary.
} Table 4.6
; Meadow Seed Mix
� I %Wei ht %Puri %Germination
Redtop or Oregon bentgrass 20 92 85
A ostis alba or A ostis ore onensis
Red fescue 70 98 90
( Festuca rubra
White dutch clover 10 98 90
Tri olium re ens
! Maintenance • Any seeded areas that fail to establish at least 80 percent cover (100
Standards percent cover for areas that receive sheet or concentrated flows) shall
'I be reseeded. If reseeding is ineffective, an alternate method, such as
sodding, mulching, or nets/blankets, shall be used. If winter weather
prevents adequate grass growth, this time limit may be relaxed at the
� discretion of the local authority when sensitive areas would otherwise
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� • After adequate cover is achieved, any areas that experience erosion
shall be reseeded and protected by mulch. If the erosion problem is
� drainage related, the problem shall be fixed and the eroded area
� reseeded and protected by mulch.
� • Seeded areas shall be supplied with adequate moisture, but not watered
to the extent that it causes runoff.
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121: M Ichin
BMP C u
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I Purpose The purpose of mulching soils is to provide immediate temporary
protection from erosion. Mulch also enhances plant establishment by
conserving moisture, holding fertilizer, seed, and topsoil in place, and
� moderating soil temperatures. There is an enormous variety of mulches
that can be used. Only the most common types are discussed in this
section.
IConditions of Use As a temporary cover measure, mulch should be used:
� • On disturbed areas that require cover measures for less than 30 days.
• As a cover for seed during the wet season and during the hot summer
months.
� • During the wet season on slopes steeper than 3H:1 V with more than 10
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feet of vertical relief.
I • Mulch may be applied at any time of the year and must be refreshed
periodically.
I Design and For mulch materials, application rates, and specifications, see Table 4.7.
Installation Note: Thicknesses may be increased for disturbed areas in or near
Specifications sensitive areas or other areas highly susceprible to erosion.
IMulch used within the ordinary high-water mark of surface waters should
be selected to minimize potential flotation of organic matter. Composted
i organic materials have higher specific gravities (densities) than straw,
wood, or chipped material.
Maintenance • The thickness of the cover must be maintained.
� Standards
� • Any areas that experience erosion shall be remulched and/or protected
with a net or blanket. If the erosion problem is drainage related, then
Ithe problem shall be fixed and the eroded area remulched.
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4-20 l�ol��me 11 — Ccrs!ructicn Storm��,�ater Pol!u!ion Prel%en?ior Februar�,; 2005
ITable 4.7
Mulch Standards and Guidelines
� Mulch Application
Material uali Standards Rates Remarks
Straw Air-dried;free from 2"-3"thick; 5 Cost-effective protection when applied with adequate
J undesirable seed and bales per 1000 sf thicla�ess. Hand-application generally requires greater
I coarse material. or 2-3 tons per thickness than blown straw.The thickness of straw may be
acre reduced by half when used in conjunction with seeding. In
windy areas straw must be held in place by crimping,using a
I tackifier,or covering with netting. Blown straw always has
to be held in place with a tackifier as even light winds will
blow it away.Straw,however,has several deficiencies that
should be considered when selecting mulch materials. It
I often introduces and/or encourages the propagation of weed
species and it has no significant long-term benefits. Straw
should be used only if mulches with long-term benefits are
� unavailable locally. It should also not be used within the
ordinary high-water elevation of surface waters(due to
flotation).
� Hydromulch No growth Approx.25-30 Shall be applied with hydromulcher. Shall not be used
inhibiting factors. lbs per 1000 sf without seed and tackifier unless the application rate is at
or 1500 -2000 least doubled. Fibers longer than about'/.-1 inch clog
]bs per acre hydromulch equipment. Fibers should be kept to less than'/.
� inch.
Composted No visible water or 2"thick min.; More effective control can be obtained by increasing
Mulch and dust during approx. 100 tons thickness to 3". Excellent mulch for protecting final grades
I Compost handling. Must be per acre(approx. until landscaping because it can be directly seeded or tilled
purchased from 800 lbs per yard) into soil as an amendment. Composted mulch has a coarser
supplier with Solid size gradation than compost.It is more stable and practical
Waste Handling to use in wet areas and during rainy weather conditions.
� Permit(unless
exempt).
Chipped Site Average size shall 2" minimum This is a cost-effective way to dispose of debris from
I Vegetation be several inches. thickness clearing and grubbing,and it eliminates the problems
� Gradations from associated with buming. Generally, it should not be used on
fines to 6 inches in slopes above approx. 10%because of its tendency to be
length for texture, uansported by runoff: It is not recommended within 200
I variation,and feet of surface waters. If seeding is expected shortly after
interlocking mulch,the decomposition of the chipped vegetation may tie
properties. up nutnents important to grass establishment.
I Wood-based No visible water or 2"thick;approx. This material is often called"hog or hogged fuel." It is
Mulch dust during 100 tons per acre usable as a material for Stabilized Construction Entrances
handling. Must be (approx.800 lbs. (BMP C 105)and as a mulch. The use of mulch ultimately
I purchased from a per cubic yard) improves the organic rnatter in the soil. Special caution is
supplier with a Solid advised regarding the source and composition of wood-
Waste Handling based mulches. Its preparation typically does not provide
Permit or one any weed seed control,so evidence of residual vegetation in
I exempt from solid its composition or known inclusion of weed plants or seeds
waste regulations, should be monitored and prevented(or minimized).
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I BMP C123: Plastic Covering
I� Purpose Plastic covering provides immediate, short-term erosion protection to
slopes and disturbed areas.
� Conditions of • Plastic covering may be used on disturbed areas that require cover
Use measures for less than 30 days, except as stated below.
I • Plastic is particularly useful for protecting cut and fill slopes and
stockpiles. Note: The relatively rapid breakdown of most polyethylene
sheeting makes it unsuitable for long-term(greater than six months)
I applications.
I • Clear plastic sheeting can be used over newly-seeded areas to create a
� greenhouse effect and encourage grass growth if the hydroseed was
installed too late in the season to establish 75 percent grass cover, or if
the wet season started earlier than normal. Clear plastic should not be
j used for this purpose during the summer months because the resulting
Ihigh temperatures can kill the grass.
• Due to rapid runoff caused by plastic sheeting,this method shall not be
l used upslope of areas that might be adversely impacted by
� concentrated runoff. Such areas include steep and/or unsta.ble slopes.
� • While plastic is inexpensive to purchase, the added cost of installation,
maintenance, removal, and disposal make this an expensive material,
up to $1.50-2.00 per square yard.
1 • Whenever plastic is used to protect slopes, water collection measures
� must be installed at the base of the slope. These measures include
plastic-covered berms, channels, and pipes used to covey clean
� rainwater away from bare soil and disturbed areas. At no time is clean
runoff from a plastic covered slope to be mixed with dirty runoff from
a project.
l • Other uses for plastic include:
! 1. Temporary ditch liner;
�� � 2. Pond liner in temporary sediment pond;
i 3. Liner for bermed temporary fuel storage area if plastic is not
reactive to the type of fuel being stored;
4. Emergency slope protection during heavy rains; and,
I I 5. Temparary drainpipe ("elephant trunk")used to direct water.
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Design and • Plastic slope cover must be installed as follows:
Installation 1. Run plastic up and down slope, not across slope;
Specifications
2. Plastic may be installed perpendicular to a slope if the slope length
--- is less than 10 feet;
� 3. Minimum of 8-inch overlap at seams;
4. On long or wide slopes, or slopes subject to wind, all seams should
be ta ed•
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I� 5. Place plastic into a small (12-inch wide by b-inch deep) slot trench
� � at the top of the slope and backfill with soil to keep water from
' flowing undemeath;
I 6. Place sand filled burlap or geotextile bags every 3 to 6 feet along
seams and pound a wooden stake through each to hold them in
place;
7. Ins ect lastic for ri s tears and o en seams re larl and re air
I P P P , � P � Y P
immediately. This prevents high velocity runoff from contacting
bare soil which causes extreme erosion;
I8. Sandbags may be lowered into place tied to ropes. However, all
sandbags must be staked in place.
� • Plastic sheeting shall have a minimum thickness of 0.06 millimeters.
• If erosion at the toe of a slope is likely, a gravel berm, nprap, or other
I suitable protection shall be installed at the toe of the slope in order to
reduce the velocity of runoff.
` Maintenance • Torn sheets must be replaced and open seams repaired.
( Standards
• If the plastic begins to deteriorate due to ultraviolet radiation, it must
be completely removed and replaced.
• When the plastic is no longer needed, it shall be completely removed.
' • Dispose of old tires appropriately. '
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4.2 Runoff Conveyance and Treatment BMPs
l BMP C200: Interceptor Dike and Swale
Purpose Provide a ridge of compacted soil, or a ridge with an upslope swale, at the
=j top or base of a disturbed slope or along the perimeter of a disturbed
; construction area to convey stormwater. Use the dike and/or swale to
intercept the runoff from unprotected areas and direct it to areas where
erosion can be controlled. This can prevent storm runoff from entering the
work area or sediment-laden runoff from leaving the construction site.
Conditions of Use Where the runoff from an exposed site or disturbed slope must be conveyed
Ito an erosion control facility which can safely convey the stormwater.
• Locate upslope of a construction site to prevent runoff from entering
� disturbed area.
� • When placed horizontally across a disturbed slope, it reduces the
amount and velocity of runoff flowing down the slope.
I • Locate downslope to collect runoff from a disturbed area and direct it
to a sediment basin.
Design and • Dike and/or swale and channel must be stabilized with temporary or
I� I Installation permanent vegetation or other channel protection during construction.
�i Specifications . Channel requires a positive grade for drainage; steeper grades require
�'� channel,protection and check dams.
i • Review construction for areas where overtopping may occur.
i i • Can be used at top of new fill before vegetation is established.
• May be used as a permanent diversion channel to carry the runoff.
� • -
I Sub basm tnbutary area should be one acre or less.
• Design capacity for the peak flow from a 10-year, 24-hour storm,
iassuming a Type lA rainfall distribution, for temporary facilities.
� I Altematively,use 1.6 rimes the l0-year, 1-hour flow indicated by an
j approved continuous runoff model. For facilities that will also serve
on a permanent basis, consult the local government's drainage
� requirements.
I Interce tor dikes shall meet the followin criteria:
P g
Top Width 2 feet minimum.
Height 1.5 feet minimum on berm.
Side Slope 2:1 or flatter.
I Grade Depends on topography, however, dike system minimum is
0.5%, maximum is 1%.
Compaction Minimum of 90 percent ASTM D698 standard proctor.
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February 2005 Volume I!— Construction Stormwater Pollution Prevention 4-57
IHorizontal Spacing of Interceptor Dikes:
� Average Slope Slope Percent Flowpath Length
20H:1V or less 3-5% 300 feet
(10 to 20)H:1 V 5-10% 200 feet
� (4 to 10)H:1 V 10-25% 100 feet
(2 to 4)H:1 V 25-50% 50 feet
Stabilization depends on velocity and reach
l Slopes<5% Seed and mulch applied within 5 days of dike
� construction(see BMP C121, Mulching).
Slopes 5-40% Dependent on runoff velocities and dike materials.
1 Stabilization should be done immediately using either
sod or riprap or other measures to avoid erosion.
• The upslope side of the dike shall provide positive drainage to the dike
� outlet. No erosion shall occur at the outlet. Provide energy dissipation
measures as necessary. Sediment-laden runoff must be released
through a sediment trapping facility.
! • Minimize construction traffic over temporary dikes. Use temporary
cross culverts for channel crossing.
� Interceptor swales shall meet the following criteria:
Bottom Width 2 feet minimum; the bottom shall be level.
� Depth 1-foot minimum.
Side Slope 2:1 or flatter.
Grade Maximum 5 percent, with positive drainage to a
� suitable outlet (such as a sediment pond).
Stabilization Seed as per BMP C120, Temporary and Permanent
Seeding, or BMP C202, Channel Lining, 12 inches
I thick of riprap pressed into the bank and extending
at least 8 inches vertical from the bottom.
• Inspect diversion dikes and interceptor swales once a week and after
Ievery rainfall. Immediately remove sediment from the flow area.
• Damage caused by construction traffic or other activity must be
I repaired before the end of each working day.
Check outlets and make timely repairs as needed to avoid gully formation. When
the area below the temporary diversion dike is permanently stabilized, remove the
dike and fill and stabilize the channel to blend with the natural surface.
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I 4-58 Vofume ll— Construcfron Stormwater Pollution Prevention February 2005
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BMP C207: Check Dams
IPurpose Construction of small dams across a swale or ditch reduces the velocity of
concentrated flow and dissipates energy at the check dam.
� Conditions of Use �ere temporary channels or permanent channels are not yet vegetated,
channel lining is infeasible, and velocity checks are required.
I • Check dams may not be placed in streams unless approved by the State
Department of Fish and Wildlife. Check dams may not be placed in
wetlands without approval from a permitting agency.
I • Check dams shall not be placed below the expected backwater from
any salmonid bearing water between October 1 and May 31 to ensure
that there is no loss of high flow refuge habitat for overwintering
l juvenile salmonids and emergent salmonid fry.
� Design and Whatever material is used, the dam should form a triangle when viewed
I Installation from the side. This prevents undercutting as water flows over the face of
Specifications the dam rather than falling directly onto the ditch bottom.
Check dams in association with sumps work more effectively at slowing
1 flow and retaining sediment than just a check dam alone. A deep sump
� should be provided immediately upstream of the check dam.
I • In some cases, if carefully located and designed, check dams can
remain as permanent installations with very minor regrading. They
may be left as either spillways, m which case accumulated sediment
y would be graded and seeded, or as check dams to prevent further
Isediment from leaving the site.
• Check dams can be constructed of either rock or pea-gravel filled bags.
I Numerous new products are also available for this purpose. They tend
to be re-usable, quick and easy to install, effective, and cost efficient.
� • Check dams should be placed perpendicular to the flow of water.
• The maximum spacing between the dams shall be such that the toe of
the upstream dam is at the same elevation as the top of the downstream
� dam.
• Keep the maximum height at 2 feet at the center of the dam.
I • Keep the center of the check dam at least 12 inches lower than the
� outer edges at natural ground elevation.
I • Keep the side slopes of the check dam at 2:1 or flatter.
• Key the stone into the ditch banks and extend it beyond the abutments
a minimum of 18 inches to avoid washouts from overflow around the
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iFebruary 2005 Volume ll—Construction Sformwater Pollution Prevention 4-75
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I • Use filter fabric foundation under a rock or sand bag check dam. If a I�
blanket ditch liner is used, this is not necessary. A piece of organic or ',
� synthetic blanket cut to fit will also work for this purpose.
- �
• Rock check dams shall be constructed of appropriately sized rock.
The rock must be placed by hand or by mechanical means (no
� dumping of rock to form dam) to achieve complete coverage of the
ditch or swale and to ensure that the center of the dam is lower than
( the edges. The rock used must be large enough to stay in place given
the expected design flow through the channel.
• In the case of grass-lined ditches and swales, all check dams and
I accumulated sediment shall be removed when the grass has matured
sufficiently to protect the ditch or swale -unless the slope of the swale
_ is greater than 4 percent. The area beneath the check dams shall be
1 seeded and mulched immediately after dam removal.
• Ensure that channel appurtenances, such as culvert entrances below
I check dams, are not subject to damage or blockage from displaced
stones. Figure 4.13 depicts a typical rock check dam.
Maintenance Check dams shall be monitored for performance and sediment
IStandards accumulation during and after each runoff producing rainfall. Sediment
shall be removed when it reaches one half the sump depth.
I • Anticipate submergence and deposition above the check dam and
erosion from high flows around the edges of the dam.
• If significant erosion occurs between dams, install a protective riprap
Iliner in that portion of the channel.
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I 4-76 Vofume Il— Construction Stormwater Pollufion Prevenfion February 2005
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� View Looking Upstream 1s° (0.5m)
A �
12" (150mm) j
/\� \� \ \ � � �8 o a o g��o /\ /.' i�//.//
� �//�//�//%� ��°Q���°a,Qoc���2�����' ��,.//,/ 24" (0.6m)
a o . �
NOTE: ��°o� �°oap.go�°
Key stone into channel banks and / / � /
extend it beyond the abutments a \'\� ��\'��\i\�\
minimum of 18" (0.5m)to prevent A
, flow around dam.
I Section A - A
FLOW �
1 24" (0.6m) Q,o�
O o4 00
� /� ,�.° o °p� pp=O
/'�, � � `bo ° , oOoo pO.QaO�
0
� �\�/%\// ' /% ./ e a\�/ �/•�/ / ' a
, ��,�\�,�\i\��j,\��/�������i\�j\�j /\/�
%�//�// /\��/
I
I 8'(2.4m)
, Spacing Between Check Dams
'L'=the distance such that points'A'and
I 'B'are of equal elevation.
I ��'
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go� ° �''�o• POINT'B'
O1 �°��.gY,° • � i�POINT'A' �
/��/��������� �� � �
I ���%�/j�/i�/i�/��/%�/��/ / '' �� ° �000...0
�\ �\ �\�\�\ \ \ \ °
� \\\��\�%�%�/\\%\��\/���/��/�\/�� �c ,a
� ,/����������j/��j��
i
; NOT TO SCALE
� Figure 4.13—Check Dams
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February 2005 Volume f!— Construction Sformwafer Pollufion Prevention 4-77
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� BMP C220: Storm Drain Inlet Protection
iPurpose To prevent coarse sediment from entering drainage systems prior to
� permanent stabilization of the disturbed area.
� Conditions of Use Where storm drain inlets are to be made operational before permanent
stabilization of the disturbed drainage area. Protecrion should be provided
for all storm drain inlets downslope and within 500 feet of a disturbed or
I construction area, unless the runoff that enters the catch basin will be
conveyed to a sediment pond or trap. Inlet protection may be used
anywhere to protect the drainage system. It is likely that the drainage
Isystem will still require cleaning.
Table 4.91ists several options for inlet protection. All of the methods for
-� storm drain inlet protection are prone to plugging and require a high
frequency of maintenance. Drainage areas should be limited to 1 acre or
less. Emergency overflows may be required where stormwater ponding
I would cause a hazard. If an emergency overflow is provided, additional
� end-of-pipe treatment may be required.
Table 4.9
I Storm Drain Inlet Protetion
Applicable for
Type of Inlet Emergency Paved/Earthen �
� Protection Overflow Surfaces Conditions of Use
Dro Inlet Protection
Excavated drop inlet Yes, Earthen Applicable for heavy flows. Easy '
( protection temporary to maintain. Large area
flooding will Requirement: 30'X 30'/acre
occur
Block and gravel drop Yes Paved or Earthen Applicable for heavy concentrated ,
I inlet protection flows. Will not pond.
Gravel and wire drop No Applicable for heavy concentrated
inlet protection flowa. Will pond. Can withstand
I traffic.
�
� Catch basin filters Yes Paved or Earthen Fre uent maintenance re uired. '
Curb Inlet Protection
( Curb inlet protection Small capacity Paved Used for sturdy, more compact �
with a wooden weir overflow installation.
Block and gravel curb Yes Paved Sturdy, but limited filtration.
inlet protection �
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Culvert Inlet Protection
Culvert inlet sediment 18 month expected life.
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4-82 Volume U— Construction Stormwater Pollutron Prevention February 2005
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Design and Excavated Drop Inlet Protection -An excavated impoundment around the
i Installation storm drain. Sediment settles out of the stormwater prior to entering the
� Specifications storm drain.
_ �
De th 1-2 ft as measured from the crest of the inlet structure.
P
� Side Slopes of excavarion no steeper than 2:1.
.
� I Minimum volume of excavation 35 cubic yards.
j • Shape basin to fit site with longest dimension oriented toward the
longest inflow area.
• Install provisions for draining to prevent standing water problems.
I Clear the area of all debris.
III •
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l • Grade the approach to the inlet uniformly.
� • Drill weep holes into the side of the inlet.
• Protect weep holes with screen wire and washed aggregate.
� • Seal weep holes when removing structure and stabilizing area.
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• It may be necessary to build a temporary dike to the down slope side
� of the structure to prevent bypass flow.
� Block and Gravel Filter-A barrier formed around the storm drain inlet
� with standard concrete blocks and gravel. See Figure 4.14.
1 • Height 1 to 2 feet above inlet.
� • Recess the first row 2 inches into the ground for stability.
� • Support subsequent courses by placing a 2x4 through the block I
opening. I
• Do not use mortar. I
I • Lay some blocks in the bottom row on their side for dewatering the
pool.
I • Place hardware cloth or comparable wire mesh with '/�-inch openings
aver all block openings.
• Place gravel just below the top of blocks on slopes of 2:1 or flatter. '
l • An alternative design is a gravel donut.
• Inlet slope of 3:1.
� Outlet slope of 2:1.
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i • 1-foot wide level stone area between the structure and the inlet.
' I • Inlet slope stones 3 inches in diameter or larger.
� • Outlet slope use gravel '/2- to 3/4-inch at a minimum thickness of 1-foot.
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February 2005 Volume Il— Consfruction Stormwater Pollution Prevention 4-83
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� Plan View q
Drain �a
Grate .o,uob��4�.�o o. ���o��o�
1 a��'OQ O �Q� 04_�b°�'o
�'p p�'✓,oGl opoGl�jpo. �o f�oO��� a
aJ �f�J
��'� O O� o��� Q� O :��` •O�
- �° ��� � D°c�o��
_� d��o; a:Oq o0o Concrete
�—�� d�o �• �a oo Block
.�.JO�o^o ����� O O�
0
;D'• o�C' o' p.
d.��.�.nQ Q� � o
� ��a�a o° ��L10�0 � o�aoo
Q a •, d�b �
Q,�°��°o a �° Gravel
d•fJ a'��1'o �' od �o Backfill
�O°Q � �����o
� �a�OO �o o ��Q,C-�O1
�J'��°�'Oa �'`o�_r-Ptt•0°O'O .°�o'�p��b°�'O �C
C�a��"'$o p���,q a�0o�c����j�oo
�� ��o 00 0�4000 �� o oa
} a� o oC•
I �,5`'��oQ� �- �1
�.��,
� A
Section A � l�i Cancrete Black Wire Screen or
Fifter Fabric
� Gravel Backfill �Overflow
Water Ponding Height
o,o ,o
°o•
� � Wa?er� o p
I /\/\\/\\ \\ \\ \\ \\ — \\ \\ \\ \\ \\/\\/\\//
�i��/i�/\//\//\//\//\ \//\//\//\//\//\/\/,
��\\�����\��\�� Drop Inlet \\����\\�\\��\
�,.//i.�//���//��// ��//��/\��/��/i
I ��%/j .��/i�/
Notes:
1 1. Drop inlet sediment barriers are to be used for small,nearly level drainage areas.(less than 5%)
2. Excavate a basin of sufficient size adjacent to the drop inlet.
3.The rop of the structure(ponding height)must be well below the ground elevaRon downslope to prevent
runoff from bypassing the inlet. A temporary dike may be necessary on the dowslope side of the structure.
IFigure 4.14—Block and Gravel Filter
Gravel and Wire Mesh Filter- A gravel barrier placed over the top of the
i inlet. This structure does not provide an overflow.
• Hardware cloth or comparable wire mesh with %z-inch openings.
I • Coarse aggregate.
• Height 1-foot or more, 18 inches wider than inlet on all sides.
� • Place wire mesh over the drop inlet so that the wire extends a
minimum of 1-foot beyond each side of the inlet structure.
• If more than one strip of inesh is necessary, overlap the strips.
� • Place coarse aggregate over the wire mesh.
• The depth of the gravel should be at least 12 inches over the entire
� inlet opening and extend at least 18 inches on all sides.
I4-84 Volume I!—Consfruction Stormwater Po!lution Prevention February 2005
� Maintenance • Catch basin filters should be inspected frequently, especially after
Standards storm events. If the insert becomes clogged, it should be cleaned or
lreplaced.
• For systems using stone filters: If the stone filter becomes clogged
_1 with sediment, the stones must be pulled away from the inlet and
i cleaned or replaced. Since cleaning of gravel at a construction site
may be difficult, an altemative approach would be to use the clogged
I stone as fill and put fresh stone around the inlet.
• Do not wash sediment into storm drains while cleaning. Spread all
excavated material evenly over the surrounding land area or stockpile
f and stabilize as appropriate.
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4-86 Volume!!—Consfrucfion Sformwater Pollution Prevention February 2005
�lan View
li
Badc of Sidewalk A Catch Basin
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' J� 2x4 Wood Stud
i
Back of Curb Concrete Block
�
Curb Inlet
�ao
'..��, gfl^.�;���:
•�. � ,�
�a�e � a ���� �
J��p O G�
. `�-��, ' '� '��°��
, _;K,�p�. , � I 4�0��^8 i.
I � o� ocd,�°o'�y , ! �b.ep��� �°'
� �.� ���� � ; ��,a��„���"'�
,��"'4'-'l-�•.(.i� .�Ru �� 9u R.� 4. cS�'�/ 94��i•�...
0 00 �1 0�'0, 'Joo.o:�,_.�p� Q; qo.��.
� o � • Vot'. � � e� '. o c°�-��i � �e p
�� �� ��• � ° �' o -�� �
�
b o >o� o .�4��� r���
Rq�yO�?C�{���J..l' �q�(�"�0�4/�^Qq�j�'-> q�r o, ,��;j- oaq�,�.
j �Qo� ° ���;��o�p ��� � .
J°W-� J�•'J.h�9-Y1-O QpoQ,��.. �� V`Y;� �1!^ .�.` u:��' J'� �o
^Q pd�� �,7 ('j�J
��J+ c�,�' �� "�+^��_,�. ��.�4 ��J.R�-.� •Coa.�,�ArP�-iV��' p•
v C.>o �
Wire Screen r
� Filter Fabric A Concrete Block
Section A - A 3�,"Drain Gravel
(20mm)
i '/,"Drain Gravel
� (20mm)
Ponding Height
Concrete Block
OverFl
� : °`°'. ��`'� �, 1 C
' '- Curb Inlet
�' i ':
Wire Screen or
Filter Fabric �
4 Wood Stud ';
Catch Basin �
(100x50 Timber Stud)
I
NOTES:
1.Use block and gravel type sediment barrier when curb inlet is located in gently sloping street segment,
where water can pbnd and allow sediment to separate from runoff.
2.Barrier shail allow for overflow from severe storm event.
3. Inspect barriers and remove sediment after each storm event. Sediment and gravel must be removed
from the traveled way immediately.
Figure 4.15— Block and Gravel Curb Inlet Protection
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February 2005 Volume ll— Construction Stormwafer Pollution Prevention 4-87
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Plan View
�
Back of Sidewalk
�
Burlap Sacks to Catch Basin
� _ _ Overlap onto Curb
Curb Inlet
1 Back of Curb
� t �
i ��'I 1
�VI
� RUNOFF ��
� ��_.-;�
��, _- ,
RUNOFF SPILLWAY ��
I �i�'�
� �,
;� ��
_�' � //
/ ' �
, �
�,
.,
��\ / Gravel Filled Sandbags
������. Stacked Tightly
l `�\�—.
I �_
NOTES:
I 1.Place curb type sediment barriers on gently sloping street segments,where water can pond and allow
sediment to separate from runoff.
2. Sandbags of either burlap or woven'geotextile'fabric,are filled with gravel,layered and packed tightly.
( 3.Leave a one sandbag gap in the top row to provide a spillway for overflow.
4.Inspect barriers and remove sediment after each storm event. Sediment and gravel must be removed from
the traveled way irnmediately.
� Fi ure 4.16-Curb and Gutter Barrier
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4-88 Volume ll- Construction Stormwater Pollution Prevention February 2005
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BMP C233: Silt Fence
,
Purpose Use of a silt fence reduces the transport of coarse sediment from a
construction site by providing a temporary physical barrier to sediment
1 and reducing the runoff velocities of overland flow. See Figure 4.19 for
� details on silt fence construction.
I
Conditions of Use Silt fence may be used downslope of all disturbed areas.
I • Silt fence is not intended to treat concentrated flows, nor is it intended
i to treat substanrial amounts of overland flow. Any concentrated flows
must be conveyed through the drainage system to a sediment pond.
I I The only circumstance in which overland flow can be treated solely by
a silt fence, rather than by a sediment pond, is when the area draining
- 1 to the fence is one acre or less and flow rates are less than 0.5 cfs.
� • Silt fences should not be constructed in streams or used in V-shaped
ditches. They are not an adequate method of silt control for anything
deeper than sheet or overland flow.
Joints in filter fabric shall be spliced at
I posts.Use staples,wire rings or 2^x2"by 14 Ga.wire or I
i equivalent to attach fabric to posts equivalent,ii standard
strength fabric used
I ! I
I � I I Filter fabric — ,
I c
I II I i N
,'
II � � � � �
� — 7�s�m�= — == —� � i , ��
I � Minimum 4'x4'trench
J � ' "
� I Backfill trench with native soil I
I Post spacing may be increased or 3/4"-1.5"washed gravel J�
to 8'if wire backing is used �
2"x2"wood posts,steel fence
posts,or equivalent
I
� Figure 4.19—Silt Fence
I Desi n and • Draina e area of 1 acre or less or in combination with sediment basin
g g
I, Installation in a larger site.
ISpecifications
• Maximum slope steepness (normal (perpendicular) to fence line) l:l.
• Maximum sheet or overland flow path length to the fence of 100 feet.
I
• No flows greater than 0.5 cfs.
I • The geotextile used shall meet the following standards. All geotextile
properties listed below are minimum average roll values (i.e., the test
result for any sampled roll in a lot shall meet or exceed the values
' shown in Table 4.10):
� 4-94 Volume 1!— Consfrucfion Stormwater Po!lution Prevenfion February 2005
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! Table 4.10
Geotextile Standards
1 Polymeric Mesh AOS ; 0.60 mm maximum for slit film wovens(#30 sieve). 0.30
(ASTM D4751) mm maximum for all other geotextile types(#50 sieve).
0.15 mm minimum for all fabric rypes(#100 sieve).
� Water Permittivity 0.02 sec minimum
(ASTM D4491)
Grab Tensile Strength 1801bs.Minunum for extra strength fabric.
� (ASTM D4632) 1001bs minimum for standard strength fabric. �
Grab Tensile Strength 30%maximum
1 (ASTM D4632)
IUltraviolet Resistance 70%minimum
(ASTM D4355) I
1 • Standard strength fabrics shall be supported with wire mesh, chicken
wire, 2-inch x 2-inch wire, safety fence, or jute mesh to increase the
I strength of the fabric. Silt fence materials are available that have
1 synthetic mesh backing attached.
• Filter fabric material shall contain ultraviolet ray inhibitors and
Istabilizers to provide a minimum of six months of expected usable
construction life at a temperature range of 0°F. to 120°F.
I • 100 percent biodegradable silt fence is available that is strong, long
lasting, and can be le$in place after the project is completed, if
permitted by local regulations.
` • Standard Notes for construction plans and specifications follow. Refer
to Figure 4.19 for standard silt fence details.
I The contractor shall install and maintain temporary silt fences at the
locarions shown in the Plans. The silt fences shall be constructed in
the areas of clearing, grading, or drainage prior to starting those
I activities. A silt fence shall not be considered temporary if the silt
i fence must�function beyond the life of the contract. The silt fence
shall prevent soil carried by runoff water from going beneath, through,
� or over the top of the silt fence, but shall allow the water to pass
through the fence.
� The minimum height of the top of silt fence shall be 2 feet and the
maximum height shall be 2'/z feet above the original ground surface.
The geotextile shall be sewn together at the point of manufacture, or at
I an approved location as determined by the Engineer, to form geotextile
� lengths as required. All sewn seams shall be located at a support post.
Alternatively, two sections of silt fence can be overlapped, provided
� the Contractor can demonstrate, to the satisfaction of the Engineer, that
' the overlap is long enough and that the adjacent fence sections are
close enough together to prevent silt laden water from escaping
i through the fence at the overlap.
i February 2005 Volume ll— Construction Stormwater Pollution Prevention 4-95
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The geotextile shall be attached on the up-slope side of the posts and
support system with staples, wire, or in accordance with the
� manufacturer's recommendations. The geotextile shall be attached to
the posts in a manner that reduces the potential for geotextile tearing at
the staples,wire, or other connection device. Silt fence back-up
� support for the geotextile in the form of a wire or plastic mesh is
dependent on the properties of the geotextile selected for use. If wire
I or plastic back-up mesh is used, the mesh shall be fastened securely to
the up-slope of the posts with the geotextile being up-slope of the
mesh back-up support.
! T'he geotextile at the bottom of the fence shall be buried in a trench to
� a minimum depth of 4 inches below the ground surface. The trench
shall be backfilled and the soil tamped in place over the buried portion
� of the geotextile, such that no flow can pass beneath the fence and
scouring can not occur. When wire or polymeric back-up support
mesh is used, the wire or polymeric mesh shall extend into the trench a
� minimum of 3 inches.
The fence posts shall be placed or driven a minimum of 18 inches. A
I minimum depth of 12 inches is allowed if topsoil or other soft
subgrade soil is not present and a minimum depth of 18 inches cannot
be reached. Fence post depths shall be increased by 6 inches if the
I fence is located on slopes of 3:1 or steeper and the slope is
perpendicular to the fence. If required post depths cannot be obtained,
the posts shall be adequately secured by bracing or guying to prevent
� overturning of the fence due to seciiment loading.
Silt fences shall be located on contour as much as possible, except at
the ends of the fence, where the fence shall be tumed uphill such that
Ithe silt fence captures the runoff water and prevents water from
flowing around the end of the fence.
� If the fence must cross contours, with the exception of the ends of the
fence, gravel check dams placed perpendicular to the back of the fence
shall be used to minimize concentrated flow and erosion along the
I back of the fence. The gravel check dams shall be approximately 1-
foot deep at the back of the fence. It shall be continued perpendicular
to the fence at the same elevarion until the top of the check dam
I intercepts the ground surface behind the fence. The gravel check dams
shall consist of crushed surfacing base course, gravel backfill for
walls, or shoulder ballast. The gravel check dams shall be located
I every 10 feet along the fence where the fence must cross contours.
The slope of the fence line where contours must be crossed shall not
be steeper than 3:l.
Wood, steel or equivalent posts shall be used. Wood posts shall have
minimum dimensions of 2 inches by 2 inches by 3 feet minimum
� length, and shall be free of defects such as knots, splits, or gouges.
i
! 4-96 Volume !1— Construction Stormwater Pollution Prevention February 2005
i ' �
� Steel posts shall consist of either'size No. 6 rebar or larger, ASTM A
120 steel pipe with a minimum diameter of 1-inch, U, T, L, or C shape
I steel posts with a minimum weight of 1.35 lbs./ft. or other steel posts
having equivalent strength and bending resistance to the post sizes
listed. The spacing of the support posts shall be a maximum of 6 feet.
� Fence back-up support, if used, shall consist of steel wire with a
maximum mesh spacing of 2 inches, or a prefabricated polymeric
I mesh. The strength of the wire or polymeric mesh shall be equivalent
to or greater than 1801bs. grab tensile strength. The polymeric mesh
must be as resistant to ultraviolet radiation as the geotextile it supports.
I • Silt fence installation using the slicing method specification details
follow. Refer to Figure 4.20 for slicing method details.
I The base of both end posts must be at least 2 to 4 inches above the top
of the silt fence fabric on the middle posts for ditch checks to drain
properly. Use a hand level or string level, if necessary, to mark base
� points before installation.
� Install posts 3 to 4 feet apart in critical retention areas and 6 to 7 feet
� apart in standard applications.
Instal] posts 24 inches deep on the downstrearn side of the silt fence,
and as close as possible to the fabric, enabling posts to support the
Ifabric from upstream water pressure.
Install posts with the nipples facing away from the silt fence fabric.
` Attach the fabric to each post with three ties, all spaced within the top
� 8 inches of the fabric. Attach each tie diagonally 45 degrees through
the fabric, with each puncture at least 1 inch vertically apart. In
( addition, each tie should be positioned to hang on a post nipple when
tightening to prevent sagging.
Wrap approximately 6 inches of fabric around the end posts and secure
` with 3 ties.
No more than 24 inches of a 36-inch fabric is allowed above ground
� level.
The rope lock system must be used in all ditch check applications.
' The installation should be checked and corrected for any deviation
� before compaction. Use a flat-bladed shovel to tuck fabric deeper into
the ground if necessary.
� Compaction is vitally important for effective results. Compact the soil
� immediately next to the silt fence fabric with the front wheel of the
tractor, skid steer, or roller exerting at least 60 pounds per square inch.
Compact the upstream side first and then each side twice for a total of
four trips.
February 2005 Volume 11— Construcfion Stormwater PoNution Preventron 4-97 II'
i
� . •
I • Any damage shall be repaired immediately. I�
Maintenance If concentrated flows are evident uphill of the fence, they must be
( Standards • intercepted and conveyed to a sediment pond.
• It is important to check the uphill side of the fence for signs of the
-{ fence clogging and acting as a barrier to flow and then causing
� channelization of flows parallel to the fence. If this occurs, replace the
fence or remove the trapped sediment.
I • Sediment deposits shall either be removed when the deposit reaches
approximately one-third the height of the silt fence, or a second silt
� fence shall be installed.
• If the filter fabric (geotextile) has deteriorated due to ultraviolet
breakdown it shall be re laced.
� rena�nyh.igAe �OiTlPACiNG�
mnc 2i' T m�x.es�p�a runi
.............. .. ........._....Top d Fatsic
I . �{'11M7L�11 r/Mfl�1�YN�
AtfaeM labtle b ��
1��ff�M iIO�O��M� ' �n� -
O
f"L�N—�
w,...,�..0 w..r � �oaT��n�:
I NK i.nc�1�e 49aMs �. As aeeA L�Iv�v p�und �
������RM4 � as f.�Aa�w�wM
eo P.�'1.K Y� %
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� douOlet�ny[tt
I \\/�\\/\� \�/\\\/\\//\\//\\ _ -_ - � .
/��\��//�\\� �/�)//�/��,/�
��i ��/ ���� �%�������i�\ . '
%\i�� .� � ��\������
// �j � ���/\�� ATfACFM�lENTOESA�ti[
I //\�j/\�j� � \j��\\/\\��� •c�«labec ae pwts.�nesasd.
�j\�j/�j/// ����\��\//�\//�\\ •uuue ures ues par poe�,er we�,�ap e•a e�ne.
////j//%// � �j��j\j�\�� •��.m.a��w ed�o�y.w,cw�o now�y
I \\\\\ \\ \\�\��\\
•Manp sach th on a t�ost Np�h and qyA►Mf secuetY•
No more then 24"of a 36'iabric ura�.e�s w.(sae�a.�oa�..
is aoowed abovs grarnd.
Rol ot sR lence
4�■ �P��
�
�raeea
. arte�
� compactlon
FaGdc
i /�� $$F@nCe �
I �''
.x-"'--y"----` --'�.,�"f`�
♦ . ,� . \\�� ,a\`\�'�n 'A�.,,,,'
/. �4j�' ✓ i /. �. ` �'0.�Y
,��a����l�o �. 2Q0.�Ornm��'`5°�0 0� �/�,\/\\
.. �. ����!cicfi.H,.�{'i � -. .. .. -�� �r. y�i• �' �,
' �' ', �0��'c'.•i. .ii ������� �.P%i �
�������r�!�J`\'Q;\.\�r�. . . .�r.% i ii
:;i����iy���l\r,\`%\�s�i..i4i�H�:�i�� .'�i`��i�����.� ..�.� � �. . � \��'��, . �i,
>,�y
���P� Slchg wacle
(t B rivii wldlh) Completed Instnletlon �
Yibratary pbw b not accepiable because of hoAwnEa!ct►mpacdon
Figure 4.20—Silt Fence Installation by Slicing Method
i
� 4-98 Volume II—Construction Stormwater Pollution Prevention February 2005
� � .
I BMP C240: Sediment Trap
1 Purpose A sediment trap is a small temporary ponding area with a gravel outlet
used to collect and store sediment from sites cleared and/or graded during
construction. Sediment traps, along with other perimeter controls, shall be
� installed before any la.nd disturbance takes place in the drainage area.
Conditions of Use Prior to leaving a construction site, stormwater runoff must pass through a
� sediment pond or trap or other appropriate sediment removal best
management practice. Non-engineered sediment traps may be used on-site
� prior to an engineered sediment trap or sediment pond to provide
additional sediment removal capacity.
It is intended for use on sites where the tributary drainage area is less than
I 3 acres,with no unusual drainage features, and a projected build-out time
� of six months or less. The sediment trap is a temporary measure (with a
design life of approximately 6 months) and shall be maintained until the
� site area is permanently protected against erosion by vegetation and/or
structures.
� Sediment traps and ponds are only effective in removing sediment down
to about the medium silt size fraction. Runoff with sediment of finer
grades (fine silt and clay)will pass through untreated, emphasizing the
� need to control erosion to the maximum extent first.
Whenever possible, sediment-laden water shall be discharged into onsite,
I relatively level, vegeta.ted areas (see BMP C234—Vegetated Strip). This i
is the only way to effectively remove fine particles fr�m runoff unless �
chemical treatment or filtration is used. This can be particularly useful I
� after initial treatment in a sediment trap or pond. The areas of release 'I
must be evaluated on a site-by-site basis in order to determine appropriate
locations for and methods of releasing runoff. Vegetated wetlands shall
� not be used for this purpose. Frequently, it may be possible to pump water
from the collection point at the downhill end of the site to an upslope
vegetated area. Pumping shall only augment the treatment system, not
I replace it, because of the possibility of pump failure or runoff volume in
� excess of pump capacity.
1 All projects that are constructing permanent facilities for runoff quantity
control should use the rough-graded or final-graded permanent facilities
for traps and ponds. This includes combined facilities and infiltration
� facilities. When permanent facilities are used as temporary sedimentation
facilities, the surface area requirement of a sediment trap or pond must be
met. If the surface area requirements are larger than the surface area of
! the permanent facility, then the trap or pond shall be enlarged to comply
j with the surface area requirement. The permanent pond shall also be
divided into two cells as required for sediment ponds.
4-902 Volume !1— Constructron Stormwater Pollution Prevention February 2005
II .
Either a permanent control structure or the temporary control structure
I (described in BMP C241,Temporary Sediment Pond) can be used. If a
permanent control structure is used, it may be advisable to partially restrict
the lower orifice with gravel to increase residence time while still allowing
_� dewateri.ng of the pond. A shut-off valve may be added to the control
structure to allow complete retention of stormwater in emergency
situations. In this case, an emergency overflow we�r must be added.
IA skimmer may be used for the sediment trap outlet if approved by the
Local Permitting Authority.
IDesign and • See Figures 4.22 and 4.23 for details.
Installation . If permanent runoff control facilities are part of the project, they
- I Specifications
should be used for sediment retention.
• To determine the sediment trap geometry, first calculate the design
I surface area(SA) of the trap, measured at the invert of the weir. Use
� the following equation:
SA = FS(Q2/VS)
I where
QZ = Design inflow based on the peak discharge from the
Ideveloped 2-year runoff event from the contributing
drainage area as computed in the hydrologic analysis. The
10-year peak flow shall be used if the project size, expected
Itiming and duration of construction, or downstream
conditions warrant a higher level of protection. If no
hydrologic analysis is required, the Rarional Method may
Ibe used.
VS = The settling velocity of the soil particle of interest. The
I 0.02 mm (medium silt) particle with an assumed density of
� 2.65 g/cm3 has been selected as the particle of interest and
has a settling velocity (VS) of 0.00096 ft/sec.
IFS = A safety factor of 2 to account for non-ideal settling.
I Therefore, the equation for computing surface area becomes:
1 SA = 2 x Qzl0.00096 or
2080 square feet per cfs of inflow
Note: Even if permanent facilities are used, they must still have a
surface area that is at least as large as that derived from the above
formula. If they do not, the pond must be enlarged.
• To aid in determining sediment depth, all sediment traps shall have a
� staff gauge with a prominent mark 1-foot above the bottom of the trap.
IFebruary 2005 Volume N—Construction Stormwater Pollution Prevention 4-103
• Sediment traps may not be feasible on utility projects due to the
limited work space or the short-term nature of the work. Portable
Itanks may be used in place of sediment traps for utility projects.
Maintenance • Sediment shall be removed from the trap when it reaches 1-foot in
-{ Standards depth.
� • Any damage to the pond embankments or slopes shall be repaired.
1 urface area etermined 4�� Mi� �
at top of weir �----�_�
1' Min. Overtlow
•,— � - - T - - - - - - - - 1' Min. ��
l \`•��G 3.5'-5' %' � :•'��� :: ;�:�:���. �\:`: :. 1' Min.
���, 1.5'Min. �
\+ Flat Bottom ' ��"-1.5' \�� 2'\o� RipRap�`..,
I Washed gravel \ '
Note:Trap may be formed by berm or by �eocexciie
partial or complete excavation
I Discharge to stabilized
conveyance, outlet, or
level spreader
I
IFigure 4.22 Cross Section of Sediment Trap
�
(
� I 6' Min.
_���-���—���—���—I I�-���", 1' Min. depth overflow spillway -i��I�-��1=�I�—�I�—��i—�
I � _i�—i i i—i i i—iTi=1'I,_I'� � `I I I-Ti—i:i—�Ti—i i—i i r
—; �— =1
Native soil or /�'_.i� � � .. ��=I Min. 1' depth
compacted backfill '���� ' ��. • � � • —��� 2"-4"'rock
I �I�=�!.I i� ��� .���=��� ��I ��;=1��_� Min. 1' depth 3/4"-1.5"
Geotexti�e -1 I I-'';I-;I I-1'I-1 I i-!i I-1 I I-1 I I-1� washed gravel
I
IFigure 4.23 Sediment Trap Outlet
l
_l
I4-104 Volume!1— Construction Stormwater Pollution Prevention Fe,bruary 2005
. .
A.PPENDIX A-DEFINITIONS
IAKART is an acronym for "all known, available, and reasonable methods of prevention, control,
and treatment."AKART represents the most current methodology that can be reasonably
� required for preventing, controlling, or abating the pollutants and controlling pollution associated
with a discharge.
� Applicable TNIDL means a T1VIDL for turbidity,fine sediment, high pH, or phosph�rus, which
was completed and approved by EPA before January 1, 2011, or before the date tbe operator's
complete permit application is received by Ecology, whichever is later.
I A licant means an o erator seeking coverage under this permit.
�_
� Best Mana�ement Practices (BMPs) means schedules of activities, prohibitions of practices,
maintenance procedures, and other physical, struciural and/or managerial practices to prevent or
reduce the pollution of waters of the State. BMPs include treatrnent systems, operating
� procedures, and practices to control: stormwater associated with construction activity, spillage
or leaks, sludge or waste disposal, or drainage from raw material storage.
lBuffer means an area designated by a local jurisdiction that is contiguous to and intended to
protect a sensitive area. '
fBypass means the intentional diversion of waste streams from any portion of a treatment facility.
� Calendar Day A period of 24 consecutive hours starting at 12:00 midnight and ending the
following 12:00 midnight.
I Calendar Week(same as Week)means a period of seven consecutive days starting at 12:01 a.m.
(0:01 hours) on Sunday.
Certified Erosion and Sediment Control Lead (CESCL) means a person who has current
� certification through an approved erosion and sediment control training program that meets the
minimum training standards established by Ecology(see BMP C160 in the SW1bIlvI).
lClean Water Act (CWA) means the Federal Water Pollution Control Act enacted by Public Law
92-500, as amended by Public Laws 95-217, 95-576, 96-483, and 97-117; USC 1251 et seq.
JCombined Sewer means a sewer which has been designed to serve as a sanitary sewer and a
storm sewer, and into which inflow is allowed by local ordinance.
JCommon Plan of Development or Sale means a site where multiple separate and distinct
construction activities may be taking place at different times on drfferent schedules and/or by
I different contractors, but still under a single plan. Examples include: 1)phased projects and
projects with multiple filings or lots, even if the separate phases or filings/lots will be constructed
under separate contract or by sepazate owners (e.g., a development where lots are sold to separate
� builders); 2) a development plan that may be phased over multiple years, but is still under a
I
�
IConstruction Stormwater General Permii-December 1, 2010
Page 46
t •
� consistent plan for long-term development; 3) projects in a contiguous area that may be
unrelated but still under the same contract, such as construction of a building extension and a
new pazking lot at the same facility; and 4) linear projects such as roads,pipelines, or utilities. If
the project is part of a common plan of development or sale, the disturbed area of the entire plan
_� must be used in determining permit requirements.
Composite Sample means a m�xture of grab samples collected at the same sampling point at
I different times, formed either by continuous sampling or by mixing discrete samples. May be
"time-composite" (collected at constant time intervals) or "flow-proportional" (collected either as
a constant sample volume at time intervals proportional to stream flow, or collected by
I increasing the volume of each aliquot as the flow increases while maintaining a constant time
interval between the aliquots.
� Concrete wastewater means any water used in the production, pouring and/or clean-up of
concrete or concrete products, and any water used to cut, grind, wash, or otherwise modify
concrete or concrete products. Examples include water used for or resulting from concrete
� truck/mixer/pumper/tooUchute rinsing or washing, concrete saw cutting and surfacing(sawing,
coring, grinding, roughening, hydro-demolition,bridge and road surfacing). When stormwater
comingles with concrete wastewater, the resulting water is considered concrete wastewater and
Imust be managed to prevent discharge to waters of the state, including ground water.
Construction Activitv means land disturbing operations including clearing, grading or excavation
( which disturbs the surface of the land. Such acrivities may include road construction,
construction of residential houses, office buildings, or industrial buildings, and demolition
activity.
IContaminant means any hazardous substance that does not occur naturally or occurs at greater
than natural background levels. See defmirion of"hazardous substance" and WAC 173-340-200.
IDemonstrabl�quivalent means that the technical basis for the selection of all stormwater BMPs
is documented within a SWPPP, including:
I1. The method and reasons for choosing the stormwater BMPs selected.
2. The pollutant removal performance expected from the BMPs selected.
I3. The technical basis supporting the performance claims for the BMPs selected, including
any available data conceming field performance of the BMPs selected.
I 4. An assessment of how the selected BMPs will comply with state water quality standards.
� 5. An assessment of how the selected BMPs will satisfy both applicable federal technology-
� based treatment requirements and state requirements to use all known, available, and
I reasonable methods of prevention, control, and treatment (AKART).
Department means the Washington State Deparnnent of Ecology.
Detention means the temporary storage of stormwater to improve quality and/or t�reduce the
mass flow rate of discharge.
Constrzrction Stormwater General Permit—December 1, 2010
� Page 47
i . .
� Dewaterin�means the act of pumping ground water or stormwater away from an active
construction site.
� Director means the Director of the Washington Department of Ecology or his/her authorized
representative.
i Dischar�er means an owner or operator of any facility or activity subject to regulation under
I Chapter 90.48 RCW or the Federal Clean Water Act.
I Domestic Wastewater means water carrying human wastes, including kitchen,bath, and laundry '
wastes from residences, buildings, industrial establishments, or other places, together with such
ground water infiltration or surface waters as may be present.
I Ecologv means the Washington State Department of Ecology.
I En�ineered Soils means the use of soil amendments including, but not limited, to Portland �
� cement treated base (CTB), cement kiln dust (CKD), or fly ash to achieve certain desirable soil
characteristics.
IEquivalent BMPs means operarional, source control, treatment, or innovative BMPs which result j
in equal or better quality of stormwater discharge to surface water or to ground water than BMPs
i selected from the SWMM.
�
Erosion means the wearing away of the land surface by running water, wind, ice, or other
Igeological agents, including such processes as gravitational creep.
Erosion and Sediment Control BMPs means BMPs intended to prevent erosion and
I sedimentation, such as preserving natural vegetarion, seeding, mulching and matting, plastic
� covering, filter fences, sediment traps, and ponds. Erosion and sediment control BMPs are
synonymous with stabilization and structural BMPs.
� Final Stabilization (same as fully stabilized or full stabilization) means the establishment of a
permanent vegetative cover, or equivalent permanent stabilization measures (such as riprap,
gabions or geotextiles) which prevents erosion.
Ground Water means water in a saturated zone or stratum beneath the land surface or a surface
Iwater body.
I Hazardous Substance means any dangerous or extremely hazardous waste as defined in RCW
70.105.010 (5) and (6), or any dangerous or extremely dangerous waste as designated by rule
under chapter 70.105 RCW; any hazardous sub-stance as defined m RCW 70.105.010(14) or any
� hazardous substance as defined by rule under chapter 70.105 RCW; any substance that, on the
effective date of this section, is a hazardous substance under section 101(14) of the federal
cleanup law, 42 U.S.C., Sec. 9601(14); petroleum or petroleum products; and any substance or
Icategory of substances, including solid waste decomposition products, determined by the director
IConstruction Stormwater General Permit—December 1, 2010
Page 48
i ,
�
�
Iby rule to present a threat to human health or the environment if released into the environment.
The term hazardous substance does not include any of the following when contained in an
� underground storage tank from which there is not a release: crude oil or any fraction thereof or
petroleum, if the tank is in compliance with all applicable federal, state, and local law.
� Iniection Well means a well that is used for the subsurface emplacement of fluids. (See Well.)
I Jurisdiction means a political unit such as a city,town or county; incorporated for local self-
government.
! National Pollutant Discharge Elimination S sv tem (NPDES) means the national program for
( issuing, modifying, revoking and reissuing, terminating, monitoring, and enforcing permits, and
imposing and enforcing pretreatment requirements, under sections 307, 402, 318, and 405 of the
I Federal Clean Water Act, for the discharge of pollutants to surface waters of the State from point
sources. These permits are referred to as NPDES permits and, in Washington State, are
administered by the Washington Department of Ecology.
INotice of Intent(NOI) means the application for, or a request for coverage under this general
permit pursuant to WAC 173-226-200.
� Notice of Termination (NOT) means a request for termination of coverage under this general
permit as specified by Special Condition S 10 of this permit.
I Operator means any party associated with a construction project that meets either of the
following two criteria:
i � The party has operational control over construction plans and specifications, including
the ability to make modifications to those plans and specifications; or
I • The party has day-to-day operational control of those activities at a project that are
necessary to ensure compliance with a SWPPP for the site or other permit conditions
(e.g., they are authorized to direct workers at a site to carry out activities required by the
SWPPP or comply with other permit conditions).
Permittee means individual or entity that receives norice of coverage under this general permit.
� �H means a liquid's measure of acidity or alkalinity. A pH of 7 is defined as neutral. Large
variations above or below this value are considered harmful to most aquatic life.
I H monitorin eriod means the time eriod in which the H of stormwater runoff from a site
P P
� must be tested a minimum of once every seven days to determine if stormwater pH is between
6.5 and 8.5.
I Point source means any discemible, confined, and discrete conveyance, including but not limited
to, any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, and container from which
pollutants are or may be discharged to surface waters of the State. This term does not include
return flows from irrigated agriculture. (See Fact Sheet for further explanation.)
� Construction Stormwater General Permit—December 1, 2010
' Page 49
�
i ' •
Pollutant means dredged spoil, solid waste, incinerator residue, filter backwash, sewage,
lgarbage, domestic sewage sludge (biosolids), munitions, chemical wastes, biological materials,
radioactive materials,heat, wrecked or discarded equipment,rock, sand, cellar dirt, and
� industrial, municipal, and agricultural waste. This term does not include sewage from vessels
within the meaning of section 312 of the CWA, nor does it include dredged or fill material
discharged in accordance with a pemvt issued under section 404 of the CWA.
IPollution means contamination or other alteration of the physical, chemical, or biological
properties of waters of the State; including change in temperature, taste, color, turbidity, or odor
I of the waters; or such discharge of any liquid, gaseous, solid, radioactive or other substance into
any waters of the State as will or is likely to create a nuisance or render such waters harmful,
detrimental or injurious to the public health, safety or welfare; or to domestic, commercial,
' I industrial, agricultural, recreational, or other legitimate beneficial uses; or to livestock, wild
animals, birds, fish or other aquatic life.
Process wastewater means any water which, during manufacturing or processing, comes into
direct contact with or results from the roduction or use of an raw material intermediate
� ,
P Y
product, finished product,byproduct, or waste product(40 CFR 122.1).
IReceivin water means the water body at the point of discharge. If the discharge is to a storm
sewer system, either surface or subsurface, the receiving water is the water body to which the
� storm system discharges. Systems designed primarily for other purposes such as for ground
water drainage, redirecting stream natural flows, or for conveyance of irrigation water/return
flows that coincidentally convey stormwater are considered the receiving water.
� I Representative means a stormwater or wastewater sample which represents the flow and
� characterisrics of the discharge. Representative samples may be a grab sample, a rime-
' I proportionate composite sample, or a flow proportionate sample. Ecology's Construction
��� Stormwater Monitoring Manual provides guidance on representarive sampling.
�
ISanita� sewer means a sewer which is designed to convey domestic wastewater.
Sediment means the fragmented material that originates from the weathering and erosion of
� rocks or unconsolidated deposits, and is transported by, suspended in, or deposited by water.
Sedimentation means the depositing or formation of sediment.
� Sensitive area means a water bod , wetland, stream, a uifer rechar e area, or cl�a�el m��rat�on
Y 9 � b
zone. j
I , �I
� SEPA (State Environmental Policy Act) means the Washington State Law, RCW 43.21 C.020, '�
� intended to prevent or eliminate damage to the environment.
I� �
Si�nifica.nt Amount means an amount of a pollutant m a discharge that is amenable to available
Iand reasonable methods of prevention or treatment; or an amount of a pollutant that has a
� Construction Stormwater General Permit—December 1, 2010
� ' Page 50
I reasonable potential to cause a violation of surface or ground water quality or sediment
management standards.
� Si ificant concrete work means eater than 1000 cubic ards oured concrete or rec cled
� � Y P Y
� concrete over the life of a project.
Sigmficant Contnbutor of Pollutants means a facility determmed by Ecology to be a conmbutor
of a significant amount(s) of a pollutant(s)to waters of the State of Washington.
� Site means the land or water area where any "facility or activity" is physically located or
conducted.
� Source control BMPs means physical, structural or mechanical devices or facilities that are
intended to prevent pollutants from entering stormwater. A few examples of source control
jBMPs are erosion control practices, maintenance of stormwater facilities, constructing roofs over
� storage and working areas, and directing wash water and similar discharges to the sanitary sewer
� or a dead end sump.
Stabilization means the application of appropnate BMPs to prevent the erosion of soils, such as,
� temporary and permanent seeding,vegetative covers, mulching and matting, plastic covering and
�
sodding. See also the definition of Erosion and Sediment Control BMPs.
I Storm drain means any drain which drains directly into a storm sewer system, usually found
along roadways or in parking lots.
� Storm sewer s, s�� tem means a means a conveyance, or system of conveyances (including roads
with drainage systems,municipal streets, catch basins, curbs, gutters, ditches, manmade
channels, or storm drains designed or used for collecting or conveying stormwater. This does
� not include systems which are part of a combined sewer or Publicly Owned Treatment Works
(POTV� as defined at 40 CFR 122.2.
� Stormwater means that portion of precipitation that does not naturally percolate into the ground
or evaporate, but flows via overland flow, interflow,pipes, and other features of a stormwater
drainage system into a defined surface water body, or a constructed infiltration facility.
� Stormwater Management Manual (SWMM1 or Manual means the technical Manual published by
Ecology for use by local governments that contain descriptions of and design criteria for BMPs
� to prevent, control, or treat pollutants in stormwater.
Stormwater Pollution Prevention Plan �SWPPP�means a documented plan to implement
1 measures to identify, prevent, and control the contamination of point source discharges of
stormwater.
I Surface Waters of the State includes lakes, rivers, ponds, streams, inland waters, salt waters, and
all other surface waters and water courses within the jurisdiction of the state of Washington.
)
! Construction Stormwater General Permit—December 1, 2010
Page 51
� i � -
ITemporary Stabilization means the exposed ground surface has been covered with appropriate
materials to provide temporary stabilization of the surface from water or wind erosion. Materials
l include,but are not limited to,mulch, riprap, erosion control mats or blankets and temporary
cover crops. Seeding alone is not considered stabilization. Temporary stabilization is not a
substitute for the more permanent"fmal stabilization."
� Total Maximum Dail Load TNIDL means a calculation of the maximum amount of a ollutant
�
that a water body can receive and still meet state water quality standards. Percentages of the
Itotal maximum daily load are allocated to the various pollutant sources. A TMDL is the sum of
the allowable loads of a single pollutant from all contributing point and nonpoint sources. The
I TMDL calculations must include a "margin of safety" to ensure that the water body can be
protected in case there are unforeseen events or unknown sources of the pollutant. The
calculation must also account for seasonable vananon m water quality.
ITreatment BMPs means BMPs that are intended to remove pollutants from stormwater. A few
examples of treatment BMPs are detention ponds, oiUwater separators, biofiltration, and
� constructed wetlands.
Transparency means a measurement of water clarity in centimeters (cm), using a 60 cm
� transparency tube. The transparency tube is used to estimate the relative clarity or transparency
of water by noting the depth at which a black and white Secchi disc becomes visible when water
is released from a value m the bottom of the tube. A transparency tube is sometimes referred to ',
� as a"turbidity tube." I,
Turbidi means the clarity of water expressed as nephelometric turbidity units (NT`U) and '
Imeasured with a calibrated turbidimeter.
Uncontaminated means free from any contaminant, as defined in MTCA cleanup regulations.
ISee definition of"contaminant" and WAC 173-340-200.
I Waste Load Allocation (WLA� means the portion of a receiving water's loading capacity that is
allocated to one of its existing or future point sources of pollution. WLAs constitute a type of
water quality based effluent limitation(40 CFR 130.2[h]).
I Water qualitv means the chemical, physical, and biological characteristics of water, usually with
respect to its suitability for a particular purpose.
��
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I Waters of the State includes those waters as defined as waters of the United States in 40 CFR
Subpart 122.2 within the geographic boundaries of Washington State and "waters of the State" as
defined in Chapter 90.48 RCW, which include lakes, rivers, ponds, streams, inland waters,
( underground waters, salt waters, and all other surface waters and water courses within the
- � jurisdiction of the state of Washington.
I Well means a bored, drilled or driven shaft, or dug hole whose depth is greater than the largest
surface dimension. (See Injection well.)
I
i Consti�uction Stormwater General Pe��mit—December 1, 2010
Page 52
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I Wheel wash wastewater means an water used in or resultin from the o eration of a tire bath
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or wheel wash (BMP C106: Wheel Wash), or other structure or practice that uses water to
Iphysically remove mud and debris from vehicles leaving a construction site and prevent track-
out onto roads. When stormwater comingles with wheel wash wastewater, the resulting water is
� considered wheel wash wastewater and must be managed according to Special Condition S9.D.9.
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Constrzrction Stormx-ater General Per-mit— December- 1, ?01 J
Page 53
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APPENDIX B—ACRONYMS
I
AKART All Known, Available, and Reasonable Methods of Prevention, Control, and
� Treatment
BMP Best Management Practice
ICESCL Certified Erosion and Sediment Control Lead
CFR Code of Federal Regulations
I CKD Cement Kiln Dust
cm Centimeters
CTB Cement-Treated Base
� CWA Clean Water Act
DMR Discharge Monitoring Report
� EPA Environmental Protection A enc
g Y
IESC Erosion and Sediment Control
FR Federal Register
1 NOI Notice of Intent
NOT Notice of Termination
NPDES National Pollutant Discharge Elimmation System
I NTLT Nephelometric Turbidity Unit
� RCW Revised Code of Washington
lSEPA State Environmental Policy Act
SWMM Stormwater Management Manual
� SWPPP Stormwater Pollution Prevention Plan
TMDL Total Maximum Daily Load
lUIC Underground Injection Control
USC United States Code
� USEPA United States Envirorunental Protection Agency
WAC Washington Administrative Code '
WQ Water Quality
i WWHM Western Washington Hydrology Model
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Constr�ction Storn�water General Permit—December 1, 2010
Page 54
R •
Stormwater Pollution Prevention Pfan
Appendix E — Site Inspection Forms (and Site Log)
� The results of each inspection shall be summarized in an inspection report or checklist
that is entered into or attached to the site log book. It is suggested that the inspection
report or checklist is included in this appendix to keep monitoring and inspection
Iinformation in one document, but this is optional. However, it is mandatory that this
SWPPP and the site inspection forms be kept onsite at all times during construction, and
lthat inspections be performed and documented as outlined below.
At a minimum, each inspection report or checklist shall include: ,
Ia. Inspection date/times ,
b. Weather information: general conditions during inspection, ,
Iapproximate amount of precipitation since the last inspection, and ',
approximate amount of precipitation within the last 24 hours. '
Ic. A summary or list of all BMPs that have been implemented, �,I
including observations of all erosion/sediment control structures or ,
practices.
Id. The following shall be noted:
Ii. locations of BMPs inspected,
ii. locations of BMPs that need maintenance,
Iiii. the reason maintenance is needed,
iv. locations of BMPs that failed to operate as designed or
Iintended, and
v. locations where additional or different BMPs are needed, and
the reason(s) why
Ie. A description of stormwater discharged from the site. The presence
of suspended sediment, turbid water, discoloration, and%or oil
fsheen shall be noted, as applicable.
I
f. A description of any water quality monitoring performed during
Iinspection, and the results of that monitoring.
g. General comments and notes, including a brief description of an_y�
BMP repairs, maintenance or installations made as a result of the
inspection.
I h. A statement that, in the judgment of the person conducting the site
inspection, the site is either in compliance or out of compliance
with the terms and conditions of the SWPPP and the NPDES
G��D=_SIGNER\AI;TOCAD`.PROJECTS'��011`J11=5��,Engineering'.Analys�,s-Ca�cs�Docunxms`•N'ord'�311?snpdes-SN'PPPdec �2
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Sformwater Pollution Prevention Plan �
1 permit. If the site inspection indicates that the site is out of
compliance,the inspection report shall include a sumtnary of the
remedial actions required to bring the site back into compliance, as
� well as a schedule of implementation.
i. Name, title, and signature of person conducting the site inspection;
� and the following statement: "I certify under penalty of law that
this report is true, accurate, and complete, to the best of my
knowledge and belieP'.
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� When the site inspection indicates that the site is not in compliance with any terms and
conditions of the NPDES permit, the Permittee shall take immediate action(s) to: stop,
n ncom liance•
contain and cle
an u the unauthonzed dischar es or otherwise sto the o
, P g , P P �
correct the problem(s); implement appropriate Best Management Practices (BMPs),
Iand/or conduct maintenance of existing BMPs; and achieve compliance with all
a licable standards and permit conditions. In addition, if the noncompliance causes a
PP
� threat to human health or the environment, the Permittee shall comply with the
Noncompliance Notification requirements in Special Condition SS.F of the permit.
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Stormwater Pollution Prevention Plan I
( Site Inspection Form ,
General Information
� Project Name:
� Inspector Name: Title:
CESCL # :
Date: Time:
� Inspection Type: ❑ After a rain event
❑ Weekly
I ❑ Turbidity/transparency benchmark exceedance
❑ Other
Weather
l Precipitation Since last inspection In last 24 hours
� Description of General Site Conditions:
�
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' Inspection of BMPs
Element 1: Mark Clearing Limits
I BMP:
� Inspected Functioning
Location �, N Y N � Problem/Corrective Action
�I �
� BMP:
� Inspected Functioning
, Location �, N I, N � Problem/Corrective Action �
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I Element 2: Establish Construction Access
BMP: I
Location �spected Functioning problem/Corrective Action I''�
I Y N Y N NIP
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BMP:
Location �spected Functioning problem/Corrective Action
� Y N Y N NIP
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Element 3: Control Flow Rates
�
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Stormwater Pollution Prevention Plan
I
BMP:
I Inspected Functioning
Location �, N I, N � Problem/Corrective Action
�
BMP:
I Inspected Functioning
Location I, N �, N � Problem/Conective Action
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I Element 4: Install Sediment Controls
BMP:
Inspected Functioning
Location �, N I, N � Problem/Corrective Action
I
I BMP:
Location �spected Functioning problem/Corrective Action
I Y N Y N NIP
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Blv�:
ILocation �spYctN Y NioN� Problem/Corrective Action
I
BMP:
I Location �spected Functioning problem,�Corrective Action
Y N Y N NIP
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BMP:
ILocation �spected Functioning problenv'Corrective Action
Y N Y N NIP
�
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Stormwater Pollufion Prevention Plan
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Element S: Stabilize Soils
BMP:
Location �spected Functioning problem/Conective Action '
--{ Y N Y N NIP
�
I BMP:
Inspected Functioning
ILocation �, N Y N � Problem/Corrective Action
I
BMP:
ILocation �spYctN Y NioN� problem/Corrective Action '
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BMP:
I Inspected Functioning ��
Location I, N ; Y N NIP Problem/Corrective Action
II
I Element 6: Protect Slopes
BMP:
Location �spected Functioning problem/Corrective Action
IY N Y N N1P
I BMP:
Inspected Functioning
Location �, N Y N � Problem/Corrective Action
� BMP:
I Location �spYctN Y NioN� Problem/Corrective Action
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Stormwater Pollution Prevention Plan
I
�
IElement 7: Protect Drain Inlets
BMP:
� Inspected Functioning
Location 1, N Y N �p Probleriv'Corrective Action
l
BMP:
� Inspected Functioning
Location 1, N Y N �� Problem/Correcti�-e Action
I
� BMP: .
Inspected Functioning �, ,.. , ,. , , .
Location �, N Y N I�,g,
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� Elenr��rrt ��: .Slrrl�rlr.-.�� C�Ifunnrl� �r�1�! nr�tl��t�
Bl�1I'
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Locauon �,Y. �N Y N NIP " ,; � ,,,..;. � ��:.
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BMP:
I Inspected Functioning
Location Y N Y N NII' �'i�oblcm�Correct���c :�ction
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BMP:
� Location �spected Funetioning p1.�,�1em�Cor_-ecti��e _action
Y N Y N NIP
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I BMP: ^ ,
Insp�ctcd Funct�onin;�
Location Y N Y � N NIP ProblcmiCon-�cti��� .�1ct�on
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Stormwater PoUution Prevention Plan
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II
Element 9: Control Pollutants
l� BMP:
�� Inspected Functioning
Location y N Y N NIP Problem/Corrective Action
I
_�, B�:
Inspected Functioning
Location Y N Y N � Problem/Corrective Action
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1IElement 10: Control Dewatering
BMP:
l Inspected Functioning
� Location y N Y N NIP Problem/Conective Action
l;
i BMP:
I''I Location �spected Functioning problem/Corrective Action
Y N Y N NIP
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� B�:
Inspected Functioning
Location Y N I, N � Problem/Corrective Action
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l Water uali -Monitorin
Q ri
1 Was any water quality monitoring conducted? ❑ Yes ❑ No
IIf water quality monitoring was conducted, record results here: '
1
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If water quality monitoring indicated turbidity 250 NTli or greater; or transparency 6 �
� cm or less was Ecolo notified b hone within 24 hrs? �
, �
gY Y P �
❑ Yes ❑ No
IIf Ecology was notified, indicate the date, time, contact name and phone number
I�I below:
� j Date:
� Time:
Contact Name:
Phone #:
lGeneral Comments and Notes
Include BMP r airs, maintenance, or installations made as a result of the ins ection. �
I Were Photos Taken? ❑ Yes ❑ No ',
If hotos taken, describe hotos below:
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Stormwater Pollution Prevention Plan
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� Appendix F — Engineering Calculations
IDeveloped peak flowrates:
2 year peak flowrate=0.330 cfs
� 10 year peak flowrate=0.397 cfs
25 yeaz peak flowrate= 0.412 cfs
I
100 ear eak flowrate=0.671 cfs
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IThe sediment trap minimum size is 70o square feet of surface area. (the proposed
stormwater vault greatly exceeds this minimum size).
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Bremerton Townhomes January 2013
Technical Information Report
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APPEi�1DIX D
GEOTECHNICAL REPORT
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��.P�I�.�I�Yj��E Praposed sU�ure,
I Geotechnkal engineers strudure tl�eir se�vices to meet Bie speafic needs of � corr�pOsition of the design team,or
t�eir dier�.A geo�cttnical enginee�ing study cor�ed far a civil engl-- • pro�ect aurtiership.
neer may not fulflll the r�eeds�a construaion cor�rador a even arMotl�er
civil engineer.Beause each geotechnial engir�eering sh�dy�unique,�ach As a generaf r�le,alHays inform yaur geofechniCal engineer of project
geotechniral engineering report's�i�e,prepared solelyfor the dlent No charges�,wen mina or�.s�ar�d request an assessrnent of their impad.
one�ept you should�eiy on yo�r geo6echnial engine�ing r�eport withart Ge�hniral engir�rs rdnrwf aacept r�sponsibility ar liabilfty for problems
fir�t conferring w�h the geotechnial engineer who prepared it Artd nv or�e Cr�oacur b�ue thelr repnrL�do not cortsid�de�elo/xr�enLs o!which
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exc�the one originalty cont�ripta�d.
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RCBd�118 fil0� A geo�chnical enginee�ing report is based on conditions that aasted at
ISetious problans Irave occurred because those relyinp on a geotechnical t�e time Et�e sh�dy vras perfom�etl.Do not rely ort a g�oferhnla!errginear-
enpinee�ing report dd n�read it ail.Do not rely on an e�ive summary. u9����Q�Y R�l+have been�t�ted by:the passage of
Do not read selec�d elem�ts only. time;by rt�an-made even�,such as c�r�struction on or adjacer�Uo the si�;
I a by r�rinal eyeNs,s�x�as floods,earthquakes,or groundHrater fluct�a-
A u�q6P�#��IIiC���R�Ort IS BSSEd 00 tions.Alwa�sr�r�tact the geo�echnical engincer be(ore apPh��9���
FBC�'8 to d�ermine if ft is stlll re�iabfe.A minor amount af additionat testing a
I Geo�chnical enginee�s c�nsider a numbe�of unlque,projed-specific fac- analysis could prevent major probl�ns.
to�rvhe�establishing the scope of a study.Typial iactors incfude:tlie
cI'�Ys goals,objechves,�d risk rnar�gement preierences;the peneral MQSt 6EOtOC�� Ai'0 pt'O�P.S�
r�ah�re of the structure imrolved,i�size,and c:onflg�ra�ion;the loation of OpII110DS
� the strix�re on the site;and ott�er pla�ned or exfsting s�e imp�o+rements, Site explorafion identifies subsu�ace c�nditions only a�thase poir�s where
�uch as access.roa�s,parking lots,and unde�gmund u�litiess.Unless I�e subsuriace tests are conducted a samples are 1al�n.Geotechnical engi-
geokechnica)engineer who conducted the study speci�alty indiates ottt- neas review 6e1d and laboratory da�a and then apply iheir professional
� erwise,do not rely on a geoiechniaf enginee�ir�g report that v►ras: judgmer�to render an opinion about subsurface conditiorts throughoui the
• nof prepared!a you, si�.Ac�al subsur#ace cond'�tions may di�er---sometimes significantly—
• not prepared ia your project, from�ose indicated in your report Reraining tlie qeotechn9cal engi�eer
� not prepared for the specific si�ezplored,or who.develaped your repod to provide construdion observation is the
I • comple�ed bafare irr�ortant project changes were made. _ .most effe�ve method of marnging the risl�associated with unanticfpated
conditEons.
Typica!changes lha#can erode the rel�biliry of an exi�ing geotechnical
engir�erinp report include those that aifec� A Re�t's Reeom� Me Ab[�I
• the fundion of the proposed stnx�ure,as when it's changed from a Do not overreEy on the constn�ction recommendations included in your
parking garage t�an o�ice building,or from a fight industrial Plant report fiaserecor�unenda�ons a�e not 6naf,because geotechnical engi-
to a refrigerated warehouse, • , neers develop them principally from judgment and opinion.Geotechnica[
Iengineers can firra[¢e ttieir recommendations only by observinp actual
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! ES-0521
•CeoLechnical Errgineering
•Consiruction Monitoring
I� Seattle Redevelopment, LLC •Environmenbl Sciences
P.O. Box 2566
Re�ton, Washington 98056
IAttention: Mr. Marc Rousso
� Dear Mr. Rousso: .
Earth Sotutions NW, LLC (ESNW} is pleased to present this report tifled "Geatechnical
IEngineering Study, 334- Bremerton Avenue Southeast, Renton,Washington".
Based on results of our fiefdworic, the site is underlain prirnarily by native soils consisting of
Iloose to very dense sitty sand with gravel glacial tiU deposits with the exc�fion of the northem
portion of the site, where about three to four feet of loose fill is underlain by native sand and
I gravel deposits. Groundwa#er was encountered in the northem portion of the site, at depths of
between seven and one-half and eight feet below exis�ng grade. As s�ch, iacalized zones of
grounQwater seepage could be encountered during site grading operations, deperx{ing of the
� time of year and depth of excavations.
In our opinion, the proposed residential structures can be supported on competent or
recompacteol nafive soils or structural fill used to maJify existing site grades, as appropria#e.
l We antiapate competent native soif capable af providing adequate foundation support witl be
encountered at depths of between two to four feet belaw existing grades. Where loose or
unsuitable soil conditions are exposed at foundation subgrade elevations, oompactian of the
I soils to tfie specifrcations of structural fill, or overexcavation and teplac�ment with structural fi11,
� may be necessary. ESNW should have an opportunity to review the final site designs to
provide supplemental geotechnicai recommendations, as necessary.
IThe opportunit�r to be of service to you is appreaated. If you have any questior�s regarding the
content of this geotechnicaf engineering study, please call.
�
i Sincerely,
� EARTH I S , 4LC
I CC
ymond A. Coglas, P�
Principal
I 2881 152nd Avenue NE •Redmond,WA 98052 • (42�) �84-3300 • FAX(4Z5'r 284-2855 •Toll Free f866)336-8?1��
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TABLE OF CONTENTS
1 ES-0529
I PAGE
I1NTRODUCTION ........................................................................ 1
General ........................................................................... 1
Proiect Descriq�on .......................................................... . 2
ISurtace............ ....., .......................................................... 2
, Subsurface. ....................................................................... 3
Geologic Setdng........................................................ 3
IGroundwater. ..................................................................... 4
� DISCUSSION AND RECOMMENDATIONS....................................... 4
General. ........................................................................... 4
Site Preparatton and Earthworlc. .......................................... 5
` In�situ SolEs............................................................:. 5
I Structural Fill Placement......................................... . 5
Excavatfons and Sloues ..................................................... 6
I Rockeries and Modular Block Walls..................................... 6
Utiliri Trench Backfill........................................................... 7
Pavement Sections. ............................................................ 7
I Foundations ..................... ................. ............................. 8
Slab-on-Grade Floors..... . .. 8
RetaininaWalls.................................................................. 9
I Draina�e............................................ ................................. 9
Seismlc Considerations.. 10
I LfMlTAT{ONS.............................................................................. 10
Additional Services.... 10
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TABLE OF CONTENTS
� Cont'd
I ES-0521
GRAPHICS
PLATE 1 V{CINITY MAP
PLATE 2 TEST PIT LOCATION PLAN
I PLATE 3 . RETAINING WALL DRAINAGE DETAIL
PLATE 4 F�OTlNG DRA1N DETAIL
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I APPENDICES
Appendix A Field Exploration
Feld Logs
I Appendix B Laboratory Test�ata
, Sieve Anafyses
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; GEOTECHNICAL ENGINEERING STUDY
330 - BREMERTON AVENUE NORTHEAST
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RENTON, WASHINGTON
f ES-05Z1
I INTRODUCTtON
General
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, I This geotechnical engineering study was prepared for the proposed townhome developmen#to
be constrvcted at 330 - Bremertan Avenue Nartheast in Ren#on, Washington. The purpose of
I this study was to excavate a series of test pits throughout the site to characterize soil and
, groundwater conditions, perform appropriate geotechnical analyses and develop geotechnical
recommendations for the proposed developmer�t. Our scope of services for completing this
; geotechnica( engineering study included the following: .
I
� Excavating a series af test pits throughout the subject properiy using a nabber tired
� backhoe for purposes of characterizing the soil and graundwater condi�tions;
• Providing geotechnical recommendations for earthwork, structural fill reguirements,
` pavements,�and drainage faalities;
• Assessing the suitability of site soils for use as structurai fill;
,� • Providing recommencfations for soil bearing capacity, subgrade preparation, and
recommendations for faundation support, and;
,� • Providing additional geotechnical recommendations, as appropria#e.
` The following dacuments were reviewed as part of preparing this GeotecE�nica! Engineering
1 Study:
I • Autocad site map e-mailed by the Jaeger Engineering, undated;
� • Composite geafogic map of the King Area, Booth, D.B., 2006, and;
/ • King County Soil Survey {SCS).
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Proiec�Description
� We understand the site will be redeveloped with a series of townhornes and associated
' improvements. Due to the shallow topographic relief throughout the site, we anticipate minimal
grading consisting of cuts and filfs of less than approximately eight feet wilf be required to
j achieve design eleva#ions. Based on our understanding of the proposed project, the majority
af the fills will oacur in the narthem�portion af the site, in a topographic low area, where grades
� may be raised by up to eight feet.
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' The proposed residential structures will like�y cons"sst of relatively iigh�y loaded wood framing
I supported on conventional foundabans. We anticipate the majoriEy af the residential structures
� wil) incorporate crawl spave and slab-on-grade garage floors. Based o� our experience with
similar developments, we an#icipate wall loads on the order of two to four kips per lineal foot
� and slab-on-grade bading of 154 pounds per square foot (psfl.
� If the abave design assumptions are incorrec� or change, ESNW should be contacted to review
� the recommendations in this repart. ESNW shauld review the frnal design to verify that our
� geotechnical recommendations have been incorporated into the p(ans.
, Su�face
The site ls Iocated along the east side of Bremerton Avenue Northeast south of Northeast 4�'
Street in Renton, Washington. The approximate location of the subject properiy is illustrated on
the Vicinity Map (Plate 1). The site consists of an irregularly sl�aped property with a gross area
of approximate 1.9 acres that includes twa separate tax parcels. The approximate limits of the
I property are illustrated an the Test Pi# Location Plan (Plate 2).
�� The property is developed with residentia) buildings and associated structures, which will be
removed as part af the p(anned development and is surrounded by residerrtial properties.
�) The overall site topography is relative�y Ievel, except far the northem portion, where gradients
gentfy descend approximately eight feet to a topographic low creating a basin feature.
,I Ve etation throu hout tr�e site consists rimaril of relatirie rnature landsca in suRoundin
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the existing residential s#ructures.
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� ' Subsurface
� A total of five test pits were excavated throughout the subject site for purposes of assessing soil
conditions, and €or characterizing and classifying the site soils. Our test pit locations were
, fargety controlled by the presence of existing sfructures, underground utilities and relativety
extensive site development. However, our subsurFace explorations revealed relatively
' consistent soil and groundwater conditions across much of the site. Please refer to the test pit
logs pravided in Appendix A for a more detailed description of the subsurface conditions.
( To soi! was encountered at a11 of the test sites and was on the arder of four to twefve inches
P
, thick. However, based on the variable topography throughout the site, deeper areas of topsoil
� may be encountered during mass grading activities. The topsoil can be considered for use in .
- landscape or non-structural areas, �f desired.
I� Ex#ensive areas of filf were not encountered during the fieldworlc. However, test pits TP-4 and
TP-5 encountered thr�ee to four feet of loose sitt�r sand with grave[ (Unified Soil Classification
SM}fifl containing trace to moderate amounts of debris and organics.
IUnderlying the topsoil and fi11, native soils were encountered consisting primarily of silty sand
and silty sand with gravel soils (SM) in the topographically highsr areas, and�sand and gravel
I (SP, SP-SM, GP-GM) in the northem, topographically lower areas.
Geologlc Sett[ng
.� Qur review of tf�e referenced geologic map identi�ies gtacia(ly consolidated till deposifs (Qvt)
throughout the site and surrounding area. Tiil soils cons�st primarily of a non-so�ted mixture of
i compact silt, sand and gravel and are in a oonsolidated condition at depth. I
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The Ki�g County Soil Survey (SCS) indicates the presence of Alderwood gravelly sandy loam,
I six to ftfteen percent slopes (AgC} gl2cial till deposits throughout the majorrty of the site. The
, SCS describes these soils as having slow to rnoderate runoff with a modera#e erosion hazard.
I Ti�e soi! conditions encountered during our fieldwork generalfy correlate with the geologic map
, designations and the SCS classificatian, with the exception of the nortfiem portion of the
property. This area forms a basin wtiich consists of up to approximately nine feet or more of
Irecessional oufwash type sand and gravel deposits.
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I Groundwater
�
Groundwater was encountered at depths of abo�t seven and one-half to eight feet below
� existing grade in test si#es 7P-4 and TP-5, at the time of the fieldwork {July 200B). Based on
' our understanding of the proposed site grading, this area will likely be raised by up to
approximate�y eight feet. Hawever, the presence of groundwater seepage shoufd be
` anticipated in the deeper site ex�vations within this area, particula�ly for u�i�ity trench
alignments. Gro�ndwater seepage rates anc! e(evations fluctua#e depending on many factors,
including precipitation duration and intensity, the time of year, and soil conditions. In general,
Igroundwater flow rates are higher during t�e wetter, wirrter months.
�The soil deposi�,s in the rtorthern portion of the site are consistent with recessional oufwash
I soils, which typically are underlain by glacial till deposits. Therefore, the groundwater observed
during our fieldwork is likely con#ined to the northem portion of the si#e, and we anticipate any
groundwater that may be encountered within the glacial till deposits will be perched and
` relativety light to moderate.
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DISCUSS[Otd AND RECOMAAENDATIONS
IGerteral
I Based on the results of our study, construction of the proposed townt�wme development af the
subject s�te is feasible #rom a geotechnical standpoint. The primary geotechnical
considera�ons associated with the proposed devebpment Enclude site grading and earthwork,
� foundation support, structural fill placemer�t, appropriate erosion contro! and the suitability of the
on-s�te soils far use as structural fill.
Based on the resu�ts of our study, the proposed residential stnactures can be supparted on
I conventional spread and continuous foundations bearing on competent native soils or structural
fiA, as appropriate. We anticipate competent seil capable of providing adequate foundation
support wifl be encourrtered at depths of approximately two to four feet below existing grades in
I areas where cuts will likely occur. Where loose or unsuitable soil conditions are exposed at
foundation subgrade elevations, compaction of tfie soils to the s�ecifications of structural fili, or
overexcavation and replacemer�t with structuraf fil! may be necessary.
IIn our opinion, the soils generated from cuts tMroughout the site shouid generally be suitable for
use as structural fi() �rovided they are close to o�timum moisture. The site soils encountered at
I our exploration sites will generally exhibit goad soil strength when compacted to structural fill
specc�fications.
f The presence of groundwater seepage in deeper ufiility and site excavations made in the
� northem partion of the site should be anticipated. Supplemental recommandations for
controlling groundwater seepage should be provided by the geotechnical engineer during the
grading activ�ties, as appropriate. However, based on #he data obtained fram t�e test sites, and
our overaA character'txation of subsurface conditions, extensive site dewatering will likely not be
necessary for the proposed site development.
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This study has been prepared for the exclusive use of Seattle Redevelopment, LLC, and their
representatives. No warranty, expressed ar implied, is made. This study has been prepared in
1 a manner consistent with the level af care and skill ordinarily exercised by other members of ifie
profession curren�ly practicing under similar cortditions in this area. ESNW shoukl have an
Iopportunity to review final site plans to provide supplemental recommendations, as appropriate.
Site Preaaration and Earthworic
IThe primary geotect�nical consideraaons during the proposed site preparation and earthwork
activities will involve structural fft placement and compaction, site drainage and erosion control.
Iln-situ Soils �
I From a geotechnical standpoint, the silty sand and sand soils encountered at the test sites are
generally suitable for use as structural fiil. Due ta the generaffy granular nature of#he native
soils, use of these soifs throughout the structural fill and permanerrt filf slope areas of the site is
feasible from a geotechnical standpoint. The moisture sensitiv'rty of the natnre so�ls can be
generally characterized as modera#e to high. Because the native soils are moderately to higf�ly
sensfive to moisture, successful use of the on-site soils will fargely be dictated 6y the moisture
I content of the soils at the time of placement and compaction. Soifs encountered during site
excavations that are excessively over the optimum moisture content may require moisture
conditioning prior to placement and compaction. Conversely, if the native soils are found to be
dry at the time of placement, moisture conditioning through the applicahon of water may be
Inecessary prior to compaccting the soil.
1f the on-site soils cannot be successfully compacted, the use Qf an imported soil may be
necessary. Imparted soil intended for use as structurai fill should consist of a well graded
granular soi! with a maximum aggregate grain size of four inches, and a rnoisture content that is
at ar near the optimum Ievel. During wet weather conditions, imported soil intended for use as
� structural fill should consist of a well graded granular soil with a fines content of f�ve percent or
less defined as the percent passing the #200 sieve, based on the minus three-guarter inch
fracfion.
IStructural Fi11 Placement
I In general, areas #o receive structt.�ral fill should be sufficiently stripped af organic matter and
other deleterious mateRal. The observed topsoil layer throughout the majarity of the site is
relatively thin, but is also moderately compressible in its present condition. As such, the
geotechnical engineer should observe cleared and stripped areas of the site prior to structura!
� fill placement. In our opinion, areas to receive at least four feet of fill will not require stripping
prior to piacement. However, areas where no stripping will occur shauld be mowed as low as
� possible prior to placing any fill.
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Struc#uraf filf is defined as compacEed soil ptaced in foundation, slab-on-grade, and roadway
--i areas. �ifls placed to const�vct permanent slopes and throughout retaining wa(I and u#ility
� trench backfill areas are also consf�ered structura! fiFl. Soils placed �n structural areas shau[d
be compacted to a relative compaction of ninety percent, in gener�l accordance with the
maximum dry density as determined by the Madified Proctor Method (ASTM D-�557-02) �nd
placed in maximum twelve inch lif�s. In pavement areas, the upper twehre inches of the
s#ructural fill should be compacted to a relative compaction of at least 95 percent and be in
� stable non-yielding condition.
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Excavations and Stopes
IThe FederaE and state Occupation Safefy and Health Administration (�SHA/WISHA) classifies
soils in terms af minimum safe slape incfinations. Based on the soil conditions encountered
j during our feldwork, the site soifs enc�un#ered to depths of up to four f�et and the reiativeiy
cohesionless sand and gravel deposits observed in test sit�s TP-3 through TP-5, would be
classified by OSHA/VIIISHA as Type C. Temporary slopes over four feet in height.in Type C
I sails should be sloped no steeper than 1.5H:1V (Horizontal:Vertical). The glac�al tilf soils
encour�ered to depths of greater than four feet across the semainder of the site would generaify
be classfied by OSHA/W{SHA as Type A and B. Temporary slopes over four feet in height in
I Type A and Type B soils should be sloped at an inclination no steeper than 0.75H:1V and
1H:1V, respec�ively. If appropriate slapes cannot be achieved, temporary shoring may be
necessary to support the excavations.
IPermanent sbpes should maintain a gradient of 2H:1V, or flafter, and sho�ld be planted with an
appropriate species of vegetati�to e�hance stability and to minimize erosion.
IThe geotechnical engineer should observe temp�rary and permanent slopes to verify that the
inclination is appropriate, and to provide additional grading recommendations, as n�:cessary.
IRockeries and Modular Block Walls
1� our opinion, the use of rockeries or modular bloc[c walfs at this site is feasible fram a
geotechnical sfandpoint. Rockeries or maiular b[ock walls over four feet in heigfit will require
an engineered design. ESNW can provide engineered rockery and modufar block wall designs,
upon rec�uest. The geo#echnacal engineer shou(d review the final wall alignments and wall
Iheights with respect to the proposed site grading. ,
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Utilitv Trench Backfill
� ln our opinion, the soils observed at the test sites are generally suitable for support of utilfies.
Organic or highJy c�mpressible soils encountered in the trench excavations should not be used
I far supporting utilities. (n general, the native soils observeci at the test sites should generally be
sui�able for use as structural backfilE in the u�lity trench excavations, provided the soil is at or
near the op#imum maisture content at #he time of placement and compaction. Moisture
conditioning of the soils may be necessary at some[ocations prior to use as stnrctural fill. Utility
) trench badcfill should be placed and compacted to the specfications of structural fill pro�ided in
this report, ar#o the applicable specifications of the City of Renton, as appropriate.
IPavement Sections .
I The perFarmance of site pavements is largefy related to the conciition of the underlying
subgrade. To ensure adequate pavement perfoRnance, the subgrade should be in a firm and
unyielding condition when subjected to proofrolling with a loaded dump truck. Structural fill in
pavement areas should be campacted to the specfications detaifed in the Site Pr�parafion aRd
IEarthwork section of this repart. )t is possible that soft, wet, or otherwise unsuitable subgrade
areas may still exist after base grading activities. Areas of unsui#abte or yielding subgrade will
require remedial measures such as overexcavation and thicker crushed rock or structural fill
Isections prior to pavement.
For relatively lightly Ioaded pa�ements subjected to autom�biles artd occasiana! truck traffrc,
� the following pavement sections can be considered:
• Two inches of asphalt cancre#e (AC) placed over four inches of crushed rock base
I {CRB), or,
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• Two inches of AC placed over three inches of asphalt treated base (ATB).
IThe AC,ATB and CRB materials should conform to WSDOT specificat9ons.
l Heavier truck-traffic areas generally require thicker pavement sections depending on site
� usage, pavement I€fe expectancy, and site traffic. ESNW can provide appropriate pavement
section design recommendations for trudc traffic areas and right-of-way improvements, as
{ necessary. Additionally, Ehe city of Renton Road Standards may supersede the
� recommendations provided in this report
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� FoundaHons
1 Residential structures for this site ca� be supported on conventional sprea� and continuous
foundatians bearing an competent native soils or structural fill, as appropriate. We anticipate
I competent nafive soil suitable for supp�r�of fo�ndatians will genera�ly be exposed at depths of
� between two to four feet. Where loose or unsuitable sQil canditions are expased at foundafion �I,I
subgrade eleva�o�s, compactio� of the soils to the specifrcations of structural fitl, or �,
overexcavation and replacement with structural fili may be necessary. '
Assuming the foundations are supported an campefent, undis#urbed native soils or suitabfe
structural fll, the following parameters should be used for foundation design:
� • Allawable Soil Bearing Capacity 2,500 psf
j • Fridion 0.40
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• Passi�e Resistance 350 pcF{equivalent fluid)
� For short term wind anc� seismic (oading, a one-third increase in the allowable so�l bearing
capacity can be assumed. A factor-of-safety of 1.5 has beert applied to the friction and passive
� resistan�e values.
With structural loading as expected, tota! setttement in the range of ane mch is antiapated, with
� differentiai settlement of about one-half inch or tess. The majority of the settlements should
occur during constructian, as dead loads are applied.
� Slab-On-Grade Floors
I Slab-on-grade flaors for the proposed buildings shoukf be supported an a ficm and non-yielding
I subgrade consisfing of competent na�ve soil or structural fill. Unstabfe or yielding areas of the
� subgrade should be reoornpacted or overexcavated and re�faced with suitable structuraf fill
prior to construction o#the slab. A capilla�y break consisting of a minimum af four Enches of free
t�raining crushed rodc or gravel should be placed belaw the slab. The free draining materia!
should have a fines content of five percent or less (peroen# passing the #200 sieve, based on
the minus three-quarter inch fraction}. In areas where slab moisture is undesirable, installation
o#a vapor barrier below the slab should be considered.
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Retaininq Wails
1 If retaining wall wiil be utilized at this site, they should be designed to resist earth pressures and
any applicable surcharge {oads. For design, the following parame#ers can be assumed far
Iretaining wall design:
• Active Earth Pressure(Yielding Wall) 35 pcf(equivalent fluid)
I • At-Rest Earth Pressure (Restrained Wall} 5Q pcf
I • Traffic Surcharge(Passenger Vehicles) 70 psf(rectangular distribution)
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• Passive Resistance 350 pcf(equivalent fluid)
i • CoefF�cierrt of Fricction 0.40
I Additional surcharge loading from foundations, sloped backfill, or other loading sho�ld be
included in the retaining wall design, as apprflpriate. Drainage shauld be provided behind
retaining walls such that hydrostatic pressures do no# develop. if �rainage is not provided,
� hydrostatic pressures should be included in the wall design, as appropriate. ESNW shoufd
� review retaining wall designs to verify that appropriate earth pressure values and drainage have
been incorporated into design, and to provide additional recommendations, as necessary. ;
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� Retaining walls should be backflled with free draining material that extends along the height of i
the wall, and a distance of at least eighteen inches behind the wall. The upper one foot of the ;
wall backfiil can oonsist of a less permeable (surfac� sean soil, if desired. A rigid, perforated
� drain pipe shauld be placed along the base of the wall, and connected to an appropriate 'I
discharge Iocation. A typical retaining wall and drainage de#ail is illustrated on Plate 3 of this I
report. . Other drainage methods may be considered, and recommended by ESNW, as
lappropriate. ,
Draina�e �'�
I Groundwater tabEe was observed at de ths ef between seven and one-haff and ei ht feet below I
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existing grades in the northem portion of the si�e, at the time of our fieldwo�lc (July 2006). As I
Isuch, localized zones of graundwater seepage cauid be encoun#ered in the site excavatians in i,
this area, particularfy during the wetter winter montF�s. Localized zones af perched seepage
may aiso be encountered in deeper excavations within the gfacial tifl soif deposits. Temporary �
measures to control groundwater seepage and surface water runoff during constru�tEon would
likely involve interceptor trenches and sumps, as necessary.
iIn our opinion, perimeter drains should be installed at or below the invert of building footings. A j
typical footing drain detai! is provided on Plate 4 of this report.
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Seismic Considerations
I The 2003 lntemational Suilding Code specifies severaf soil profiles that are used as a basis for ��
� seismic design af structures. Based on the soil conditions observed at the test sites, Site Class '
� C, from table 1fi'15.1.1, should be used for design. '
I In our opinion, liquefaction susceptibility at this si#e can generalfy be characterized as low. The
l relative density of the site soils and the absence of a uniform, shallow groundvvater table is the
primary basis for this designation.
� LIMI7ATIONS
The recommendations ar�d conclusions provided in this geotechnical engineering stucly are
, professional opinions consistent vrr�th the (evel of care and skill tf�at is typical af other member�
� in the profession curren#iy practicing under similar candFtions in this area. A warranty is no#
expressed or irrtplied. Variations in the soil and grourtdwater oonditions observed at the tes#
sites rnay exist, and may not become evident until construction. ESNW should reeval�ate the
Icanclusians in th�s geotechnical engineering s#udy�f variations are encountered.
Additional S�rvices
ESNW should have an opportunity to r+e�iew the final design with respect to the g�otechnical
recommer�dations provided in this report. ESMN should afso be retained ta provide testing and
Iconsultation seTvices during canstruction.
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INORTH , ..'_.f�::� E � 1
i ..�
Reference: - .
I Kng Courrty -
� Map 656 ' ,�
By Thomas Brothers Maps Vcinity Map
�ated 2007 Bremerton Avenue Townhomes
' Renton, Washington
�
� NO'�:This pl�e may contain areas d co�r.ESNW cannot be Dtwn. GLS Date 07/17/2006 Ptoj. IVo. 0521
i responslble fa any subsequeM m�interpretation of the nfonnation
� resu�ing irwn�ladc&whfte repioduc6ons of this plate. Chedced SSR Date July 2006 Plate 1
i . .
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- ----- -� _� �__.__ .— __J---
I '<�z_`.'
LEGEND i �
i
I TP-1—+�—Approximate Locafion a# . �
� ESNW Test Pit, Proj. No.
ES-0521, July 2d06
� j Sub'ed S�te �.F�r i �
I_�. _j � - -
�
N07E:The graphics shown an this p}�e are not ir�ended for design �` �'
purposes or predse scale meaeunements,but anty ta�a�e the �� .
approX;mate t�bc�ons rebtive oo a,e appro�arnate bc�or►s of Test Pit Location Plan
existing and 1 a proposed sile fealues.The infa'ma�m NM�strab�d
�S��y e��d on da�a�n�zt►e�c�c me cirr�ot o�r Bremerton Avenue Townhomes
study.ESNW cannot be responsibleforsubsequerrt design changes Renton, Washington
or htterpreta�on of Uie data by ot�s.
NOTE:Tfrs plate may oontah areas dcobr.ESNW cainat be D�. GLS Date 07117I20Q6 Proj.No. Q521
respons�'ble fa any subsequent misinterpretafion of the inform�ion
' resufdng from bladc d�wh�e reproductians of this pl�e. Checked SSR Dafe Juty 2006 Plate 2 !
I
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rt��R�iw•.,c .. •�'s:�.fcf.•..
I �
�PerForated Drain Pipe
NOTE3• (Surround in Drain Rock)
I � • Free Draining Badcfill si�oufd consist
of soil having less than 5 peroent fines.
� Peroent passing#4 should be 25 to
75 percent
• Sheet Drain may be feasible in lieu SCHEMATiC ONLY-NOTTO SCALE ;
i of Free Draining Backfsll,per ESMN NOTA CONSTRUCTION DRAWING
�ecommenda�ons.
• Drain Pipe should oonsist of perforated,
I rigid PVC Pipe surrounded with 1"
� Drain Rock
I
I LEGEND: - ,:�
� Surfaoe Seal;Native So�or other
' �t ! 1
Low Pe�dity Materiat
pep' O
0 oaeo Free Dtaining SfiKtural Backfill RETAINiNG WALL Di�AINAGE DETAIL
Bremerton Avenue Townhomes
I f��r��' 1 inch Drain Rodc R2I1tOn, Washington
1�=L�L
Drwn. GLS Date 07/19/2006 Proj. No. 0521
IChecked SSR Date July 200fi Plate 3
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APPENDIX A
1 SUBSURFACE EXPLOR,4TION
I ES-0521
IThe subsurFace cond�tions at the site were explored by excavating a total of f�ve test pits. The
approximate test pit locations are iliustrated on Plate 2 of this repart. The test pit logs are
I provided in this Appendix. The subsurface explorafion was completed in July 2006.
� Logs of the test pits are presented in Appendix A. The stratiflca�on fines on the, logs represent
#he appro�amate boundaries between soil ty�es. In actuaiity, the transitions may be more
� gradual.
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I Earth SoluUona t3W,LLC
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Earth So�utions NWu.�
I SQIL CLASS�FICATlON CHART
MAJQR DIVISlONS SYMBOLS TYPICAL
,GRAPH LETTER DESCRlPTIONS
� - cLEIW •��•� w�-r,Raoen c.R.avEts.cw�v��.-
GRAVEt GRAYELS ���� GW ���T�S,LRTLE OR NO
AND
I GRAVEI.LY ,a. ;�. POORlY-6RADED GRAVELS,
so��s �,E OR NO F�IES} a�o,o4 GP ����5.�
00
COARs� °
G O�� t��xaN�o% G�FlNES�TM •Q o b GM sit�u�s'GR'�`vE1-So,ND- ,
I OF CQARSE ,
FRACTIDN ;
REfANI�ON N0.
� 4 SIEVE U�P�►BlE � CLAYEY GRRVELS�GRAVEL-SMID-
AMOi1N'T OF FlNHS) CLAY M�(TURES
�p CLEAIV SANDS SW g,e�,�pg,URLE OR MOSFIlIES LLY
� ���� AHD
� ��� SANdY
� �o.20o s� SOILS pooRtr-sr�r�n srwos,
s¢E �.rrnF oR No Fw� SP c,w�vEu.r saria.urnE oe No
�s
f � ...: `-� .
f SAl�t�s wm-! `��: ::,• ��;�: SM siLTr sw�os,saNc-siu
uo�rtwr�sox FlNES .:`:• .:.,.�`: �S
o�co� -
FRacnaN
I PA55fNG DN N0.
4StEVE �NfT F10F�t�..5� SC CLA�.SAND-CUY
INORGANIC SIt75 AND VERY FINE
� S/W09,ROCK fLOIJR SILTY OR
{ � CUYEY FiNE SANDS OR CIAYEY
i SIL1'S WRH SL]GliT PLA.S7ICITY
SiLTS 1NOFtG4NIC GLAYS OF LOVY TO
FiNE qNp ��� C� �owa�.nsixxrr,c.w�veur
{ GfiA1NED L6s5�tuw so - - cuYs.sumr cuYs,S�LTr
` CLAYS cuYs,tFaH curs
SOILS
_= 0� o�w�c sars�uw oac�w�c
— — — sn.rr cuvs oF�ow�wsncm
� —
� —
� uo��rwN sosc iraRc�nrc�c sa.Ts.�ecac�ous oa
OF IAATERUIL 15 M}{ DNFOMACEOUS FlIYE SANO OR
5MALLER 7}iNi SILTY S�iLS
IiO.200 Sf�VE
4 S� Siv�io ��auia�rr CH u�o�cuYs oF wcH
• CLAYS GREA7ER 7HAli 50 PLASTiCITY
� � ORQANIC dAYS 0�hED1UM TO
FII�H PlASfICiTY.ORGANIC SRTS
u
� HIGHLY OFtGANIC 501LS ���'"`�'"`, PT HIGHT�o�c�t�►�s�M
DUAL SYMBOLS are used to ind�ca�e bo�erline soii das5ifications.
� The discussion 9n the text of this repart is necessary far a proper uncierstanding of ttse nature
of the rrrater�al pr�sertted in the attad�ed logs.
;
t 3
�art�sow,aons t�w,u.c TEST PIT NUWIBER TP-1
2881 952nd Avenua N.E PAGE 1 OF 1
( Redmond,WA 88052
7elephone: 4252843300
Fax 4251642855
I CL�IT Sea�tfe Redevebpmc�rt PROJECT NAME Bremertan Avenue Fownhomes
pRO,IECT Nl1AIBER 0521 PROJECT LOCATION ReMon.Washirx�ton
DATE STAR'f� 7111/08 COA�PLE7FD 7119lOB (iFaOtl�D ELEVA7tON 410 ft TEST PR Sl�
� EXGIVATt01�1 CONIRAC"TnR NW�xcava�a (�ROtA�WATER LEYELS:
IXCAVATION 11ET1�IOD AT TIAI�OF F�(CAVAI'ION —
LOGf,`�BY W�F2 d�BY SSR AT B�D OF IXCAVAt10N —
N07FS Deatl10€ToDsdl�Sod 6':sod AFTER IXCAVATION --
w
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I �� �� �s�s N �g r�,zEwu�scwPnoH
o a
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0
–i Rad�ish broxm silty SAND with gravel.loose to medium denss,moist
i
SM :-
�
I :25 407.5
Brown sdty SAND wRh gravel,medium dense ro dense.moist
FAC='1.50°k
l Fn�=21`809b �.
� ' .'. -trace cabbles 4"ta T
5 '
� SM
,
i -Posa�ble seePage
j
-becomes wet
�ewmes dertse
i MC a 12.2Q96 �''B.0 401.0
Test pit terminated a!9.0 feet below ebstimg grade.Possble grou�dwater seepage at
7.D feet during excavadon.
Bottom of test pR at 9.0 feet.
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ee�,s�►aw,�c TEST PIT N�IMBER TP-2
� 288t 152nd Avenue N.E.
I + ' Redmond,WA 98052 PAGE 1 OF 1
I Telephone: 425284330Q
Faoc: .4252842855
� GYJENT Seattk Redevelopment PROJECT lIAl1E Br�nertoe Avenue Townitomes
PROJECT NUMIBER 0521 PROJECT LACA7'!OW Renton.Washl�ton
�4TE STAFtl'9) 7/11106 COI�L.ETED 7H 1J06 C3ROUND ELEYATfON 416 tt 7ESi'PIT St�
� D(CAVATION(�OMRACTOR NW 6ccavatina C'ROUND WATQt LEYEL3:
E7CCAVA7fON NETHOD AT'�OF D(CAVA170N --
LOO�ED BY WLR CHECI�BY 55R AT B�ID OF IXCAVATION —
I NOTE3 Deflth of T.opsod&5od 6':sod AFTQt IXCAYA710N —
i '
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�� y U
I �� a? TE5T5 y g O NLATERIAL DESCRIPTiON
� �z � �
i � . Reddsh brown sity SAND wRh gravel,ioose ro medtum dense,rtwist
I -
I 51u1 =�:
�
�
I AAC=6.60% • '�4.0 4oa.
Gray sllry SAND with gravd,med'wm dense to dense�moist
! I
i
I � ; -cobbks up to B'
i
-bacomes very dense
,:;ao �becomas wet 402.0
AAC=9.109G
( 7esl pitberminabed at 8.0 teet beEow e�attr�prade.No groundwater encourttered during
excava6on.
� Barttam of tes!p@ at 8.0 feet.
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��r'S°r�'°�''"'','lc TEST PIT NUMBER TP�
2881 152nd Avenue N.E. PAGE 1 OF 1
iRedmor�d.WA 98Q52
� Telephone:.4252843300
Fa�c 4252842855
I CiIENT SeaEtk Redeveloomerrt PROJECT NA6E BromerMn Aven�Tamhames _
PROJECT NU�IBFJt p521 PROJECT LOCA71dN ReRton.Washin9ton
DATE STARTID 711'1/06 COMPLET� 7N 1/06 GROItND ElEVAT10N 420 ft TES�PfT S�
� D(CAVATION COHTRACTOR NW ExcavaHna GROUI�WATfR LEV9..9:
D(CAVA?lON NE'�}i0D AT TINIE OF DCCAVATION —
LOi�SY WLR CNECKED BY SSR AT EMD OF DCCAVA7'!ON --
I NOiFS Devfh of ToosoN&5od 12':sod�blackbem busF�ea AFTER IXCAVATION --
w
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I �c �� 7ESTS y �O MATFRIAL bESCRIPTION
1 � �z � n
0
-� &own s�ty SAND w�9r�v�ef,loose�mokt
I � ,:;. .•; -cobbles up to 6"
1 .
l �;3.5 �18.5
{ MC=3.30% �Y P�Y 9�d SAND withh sAt and gravel.rt�edium den�e,moist
I Fines=9.10%
5 � �- ;:: �
` SM
I s.o a�a.o
�_ a
G�'aY P��Y�GRAVEL w@h sand,bose to medium dense,moist
� '�y� O
M�s�.�x 7.5 4125
Test pit tertninated at 7.5 feet below e�ting grade.No grour�dwater encauntered dufing
excavaUon.
� Botbrn d test pit at 7.5 feet
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��,s�n�r,w,LLC TEST P�'T t�UMBER TP-4
� 2881 152nd Avenue N.E.
� � , Redmond,WA 98052 PAC� 1 OF 1
, 'Pelephor�: 4252843300
Fax 4252842855
� CI.IENT Seattle Redeyebqmer�t PROJECT NAIVI� Bremerdonllvenue 7owN�omes �
'� PROJEC7 NUMBER 0521 PROJEC'f LOC�ATlON _Renton.Washinaton
DATE STAR7ED 7171106 OONPLEi� 7l11106 G�tOU[�O ELEVATION 400 ft TFST Pff S�
� IXCAVAT10k CONiRAC7�OR NW Excavaflna GROUND WASBi��c.
DCCJIYATION METH00 S AT T�IIE OF D(CAVATION 7.5 ft/Elev 392.5 R
LD(30ED 6Y WLR pf�Q�B1f SSR AT 9�D OF IXCAVA710N —
l NOTeS Denfh o[Topsol&Sod 4",sod AF[ER IXGVATION ---
I
�� N �c�
� w
w v �� TESTS � �O #AA7ERIAL DESCRIPTION
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m
I , Brown silty SAND with grevel,Iaose,maist(Fdl}
MC=8.1 D9i
� SM
I
I4.0 ?96.0
Brown pooriy graded fine to medium SAND with silt,loose,wet
5 �
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BoBom of test pR at 8.5 faet.
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��'�'°"s"'"�"-� TES7 P[T NUMBER TP-5
2881 152nd Avenue N.E.
I Redmond,WA 98052 PAGE 1 OF 1
Telephone: 4252843300
Fa�c 42528428�
CUENT Seattle RedQve�oRment PkOJECT NAAiE &emercon Avenue Tw�rt�homes
IPROJECT NUMBER 0521 PRO,�CT LOCATION Renton.Washtnaton
DW1'E STARTED 7/t 1H06 COI�PLET� TJt 1/06 GROl1ND aEVAI'!OH 400 ft '1'EST P(T Si�
� IXCAVATION COM'RACT'OR FtW Ezprvatlr� GROIMD WAY6t L£VELS:
DCCAVATIOlt 1dETHOD AT T1NIE OF IXCAVATfON --
LOGGED BY WLR d�ECl�D SY SSR AT Q�D OF IXCAVATION —
N07ES Deotih ot TopsoN�Sod 4":sod AFTER D(CAVATIOl1 —
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8oltom of test pit at 10.0 fceL
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LABORATORY TEST DATA
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REPORT DtSTRIBUTiON
1 ES-0521
I4 COPiES Seattle Redevelapment, LLC
P.O. Box 2�6
IRenton, Washingbon 98056
Atbentlon; Mr. Marc Rousso
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I1COPY Jaeger Engineering
9419 South 204�' Place
iKent, Washington 98031
Attention: Mr. Jim Jaege�
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Eerth Soludons NW,LLC
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� Bremerton Townhomes January 2013 II
� Technical Information Reporf
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APPENDIX E
j DRAINAGE CO�VINPLAINT RESULTS
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� P:l 3112� �eneineering!...i���ord i TIR%Final-Revised TIR 10-26-2012.doc
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From: Gary Fink<GFink@Rentonwa.gov>
I i To: "'Barry@ConceptEng.com"'<Barry@ConceptEng.com>
� Date sent: Mon, 30 Jul 2012 14:10:42 -0700
i Subject: Review of Drainage Issues -320 �330 Bremerton Ave NE, Renton
-� Barry,
�
My apologies for the delay getting back to you. I have reviewed the area around the site at 320
& 330 Bremerton Ave NE, along with the area of drainage course described in your telephone
� call, including Duvall Ave, Field Ave, SE 1St, & Hoquiam Ave SE. Records do not indicate any
instance of significant flooding, erosion or other drainage issues within this area.
l
�
� Thank you for your inquiry. Please feel free to contact me If you have further question. ,
� I
�
Best Regards,
� Gary Fink
i
� City of Renton
� Utility Systems Division -Surface Water Utility
� Phone:(425)430-7392/ Fax:(425)430-7241
GFink@RentonWa.gov
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Printed for , 30 Jul 2012, 14:18 Page 1 of 1
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Bremerton Townhomes January 2013 I
�
Technical Information Reporf i,
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APPENDIX F I�
BOND QUANTITY WORKSHEET
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P:%�1125 !engineering i...!word i TTR i�Fina1-Re.ised TIR 10-26-2012.doc
Web date: 12/02/2008
Site Improvement Bond Quantity Worksheet
� King County �
Department of Development & Environmental Services
900 Oakesdale Avenue Southwest
Renton, Washington 98057-5212 For alternate formats, call 206-296-6600.
206-296-6600 TTY 206-296-7217
Project Name: BREMERTON TOWNHOMES Date: 29-Oct-12
�ocation: 320 & 330 Bremerton Ave NE, Renton, WA Project No.: U-120093
Activity No.:
Note: All prices include labor, equipment, materials, overhead and
Clearing greater than or equal to 5,000 board feet of timber? profit. Prices are from RS Means data adjusted for the Seattle area
or from local sources if not included in the RS Means database.
_ yes XXX no
If yes, ,
Forest Practice Permit Number: �
(RCW 76.09)
Page 1 of 9
Unit prices updated: 02/12/02
Version: 11/26/2008
KC Bond Quantity Worksheet-10-29-2012 Report Date: 10/29/2012
_-– --- - _- —__ —_ �___ ------- �
Site Improvement Bond Quantity Worksheet Webdate: 12/02/2008
Unit #of �
Reference# Price Unit Quantity Applications Cost
EROSION/SEDIMENT CONTROL Number
F3acktill �� cr�m���action �mh,�nkmcnt ESC-1 $ .`i fi; CY
Gheck dams,4"minus rock ESG2 SWUM 5.4.6.3 $ 67.51 Each 9 1 608
Crushed surfacing 1 1/4"minus ESC-3 WSDOT 9-03.9(3) $ 85.45 CY
Ditching ESC-4 $ 8.08 CY 35 1 283
Excavation-bulk ESC-5 $ 1.50 CY
Fence, silt ESC-6 SWDM 5.4.3.1 $ 1.38 LF 1275 1 1760
Fence,Temporary(NGPE) ESC-7 $ 1.38 LF 300 1 414
Hydroseeding ESC-8 SWDM 5.4.2.4 $ 0.59 SY
Jute Mesh ESC-9 SWDM 5.4.2.2 $ 1.45 SY
Mulch, by hand,straw, 3"deep ESC-10 SWDM 5.4.2.1 $ 2.01 SY
Mulch, by machine, straw, 2"dee ESC-11 SWDM 5.4.2.1 $ 0.53 SY
Piping, temporary, CPP, 6" ESC-12 $ 10.70 LF
Piping,temporary, CPP, 8" ESC-13 $ 16.10 LF
Piping, temporary, CPP, 12" ESC-14 $ 20.70 LF 55 1 1139
Plastic covering,6mm thick,sandbagged ESC-15 SWDM 5.4.2.3 $ 2.30 SY
Rip Rap, machine placed; slopes ESC-16 WSDOT 9-13.1(2) $ 39.08 CY
Rock Construction Entrance, 50'x15'x1' ESC-17 SWDM 5.4.4.1 $ 1,464.34 Each
Rock Construction Entrance, 100'x15'x1' ESC-18 SWDM 5.4.4.1 $ 2,928.68 Each 1 1 2929
Sediment pond riser assembly ESC-19 SWDM 5.4.5.2 $ 1,949.38 Each 1 1 1949
Sediment tra , 5' high berm ESC-20 SWDM 5.4.5.1 $ 17.91 LF 110 1 1970
Sed.trap, 5'high,riprapped spillway berm section ESC-21 SWDM 5.4.5.1 $ 68.54 LF
Seeding, by hand ESC-22 SWDM 5.4.2.4 $ 0.51 SY
Sodding, 1"deep, level ground ESC-23 SWDM 5.4.2.5 $ 6.03 SY
Sodding, 1"deep, sloped ground ESC-24 SWDM 5.4.2.5 $ 7.45 SY
TESC Supervisor ESC-25 $ 74.75 HR 8 1 598
Water truck, dust control ESC-26 SWDM 5.4.7 $ 97.75 HR 24 1 2346
1I1�F�� ,, . , � ,.� .� ,... �u���
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Each
ESC SUBTOTAL: $ 13,994.55
30°/a CONTINGENCY&MOBILIZATION: $ 4,198.37
ESC TOTAL: $ 18,192.92
COLUMN: A
Page 2 of 9
Unit prices updated: 02/12/02
Version: 11/26/ZOOf3
KC Bond Quantity Worksheet-iQ-29-2012 Report Date: 10/29/2012
-.- -- --
Site Improvement Bond Quantity Worksheet � � "'e��T� ,v°�`°� ,
Existing Future Public Private Quantity Completcd ,
Right-of-Way Right of Way Improvements (Bond Reduction)"
&Drainage Facilities Ouant.
Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Complete Cost
� �
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Backfill&Com action-embankment GI-1 $ 5.62 CY 25 140.50 100 562.00 3875 21,777.50
Backfill&Compaction-trench GI-2 $ 8.53 CY
Clear/Remove Brush,by hand GI-3 $ 0.36 SY
Clearin /Grubbin /Tree Removal GI-4 $ 8,876.16 Acre 0.059 523.69 0.373 3,310.81 1.467 13,021.33
Excavation-bulk GI-5 $ 1.50 CY 975 1,462.50 1803 2,704.50
Excavation-Trench GI-6 $ 4.06 CY
Fencing,cedar,6'high GI-7 $ 18.55 LF
Fencing,chain link,vinyl coated, 6'high GI-8 $ 13.44 LF
Fencing,chain link,gate,vinyl coated, 2 GI-9 $ 1,271.81 Each
Fencing,split rail,3'high GI-10 $ 12.12 LF
Fill 8�compact-common barrow GI-11 $ 22.57 CY
Fill&compact-gravel base GI-12 $ 25.48 CY
Fill&compact-screened topsoil GI-13 $ 37.85 CY
Gabion, 12"deep,stone filled mesh GI-14 $ 54.31 SY
Gabion, 18"deep,stone filled mesh GI-15 $ 74.85 SY
Gabion,36"deep,stone filled mesh GI-i6 $ 132.48 SY
Grading,fine,by hand GI-17 $ 2.02 SY
Grading,fine,with grader GI-18 $ 0.95 SY
Monuments,3'long GI-19 $ 135.13 Each 1 135.13 1 135.13
Sensitive Areas Sign GI-20 $ 2.88 Each
Sodding, 1"deep,sloped ground GI-21 $ 7.46 SY
Surveying,line&grade GI-22 $ 788.26 Da 2 1,576.52 5 3,941.30 8 6,306.08
Surveying,lot location/lines GI-23 $ 1,556.64 Acre 0.059 91.84 0.373 580.63 1.467 2,283.59
Traffic control crew(2 flag ers) GI-24 $ 85.18 HR 24 2,044.32
Trail,4"chi ed wood GI-25 $ 7.59 SY
Trail,4"crushed cinder GI-26 $ 8.33 SY
Trail,4"top course GI-27 $ 8.19 SY
Wall,retaining,concrete GI-28 $ 44.16 SF
Wall,rockery GI-29 $ 9.49 SF 1000 9,490.00
Page 3 of 9 SUBTOTAL 4,512.01 9,992.36 55,583.00
Unit prices updated: 02/12/02
'KCC 27A authorizes only one bond reduction. VefSlOn: 11/26/08
KC E3ond(luantiry Worksheet-10-29-2012 Report Date: 10/29/2012
-.___ -- _..__._... _ .___ i
Site Improvement Bond Quantity Worksheet -� We� ,v°�'� - .-
Existing Future Public Private Bond Reduction* �
Right-of-way Right of Way Improvements
' &Drainaye Facilities Quant.
Unit Price Unit ��2uant. Cost Quant. Cost Ouant Gost Cornplete Cost
�,,. - �,��, � ..,, ,. „ �M, „ ,.,
,� , , ,
ROAU�I'��, � � �r� � : ",� �'° ����, " #�� i '� ���.� �����"' ��� '
AC Grindin ,4'wide machine<1000s RI-1 $ 28.00 SY
AC Grinding,4'wide machine 1000-200 RI-2 $ 15.00 SY
AC Grinding,4'wide machine>2000s RI-3 $ 7.00 SY
AC Removai/Disposal/Repair RI-4 $ 67.50 SY 75 5,062.50
Barricade,type I RI-5 $ 30.03 LF
Barricade,type III(Permanent) RI-6 $ 45.05 LF
Curb&Gutter,rolled RI-7 $ 17.00 LF
Curb&Gutter,vertical RI-8 $ 12.50 LF 210 2,625.00 695 8,687.50
Cur6 and Gutter,demolition and disposa RI-9 $ 18.00 LF
Curb,extruded asphalt RI-10 $ 5.50 LF
Gurb,extruded concrete RI-11 $ 7.00 LF
Sawcut,asphalt,3"depth RI-12 $ 1.85 LF 220 407.00
Sawcut,concrete,per 1"depth RI-13 $ 1.69 LF 220 371.80
Sealant,asphalt RI-14 $ 1.25 LF
Shoulder,AC, (see AC road unit rice) RI-15 $ - SY
Shoulder,gravel,4"thick RI-16 $ 15.00 SY 196 2,940.00
Sidewalk,4"thick RI-17 $ 35.00 SY 103 3,605.00 375 13,125.00 23 805.00
Sidewalk,4"thick,demolition and dispos RI-18 $ 29.50 SY
Sidewalk,5"thick RI-19 $ 38.50 SY
Sidewalk,5"thick,demolition and dispos RI-20 $ 37.50 SY
Sign,handicap RI-21 $ 85.28 Each
Striping,per stall RI-22 $ 5.82 Each
Striping,thermoplastic,(for crosswalk) RI-23 $ 2.38 SF
Striping,4"reflectorized line RI-24 $ 0.25 LF
Page 4 of 9 SUBTOTAL 15,011.30 21,812.50 805.00
Unit prices updated: 02/12/02
"KCC 27A authorizes only one bond reduction. VerSlOn: 11/26/08
KC Bond Quantity Worksheet-10-29-2012 Report Date: 10/29/2012
Site Im rovement Bond Quantit Works — We�� ,v°�°°S
p y heet .
Existing Future Public Private Bond Reduction" `
Right-pf-way Right of Way Improvements
&Drainage Facilities QuanL
Unit Price Unit Quant Gost Quant. Cost C,�uant. Cost Complete Cost
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Fur KCRS'93,(additional 2.5"base)add RS-1 $ 3.60 SY
AC Overlay, 1.5"AC RS-2 $ 11.25 SY
AC Overla ,2"AC RS-3 $ 15.00 SY
AC Road,2",4"rock,First 2500 SY RS-4 $ 21.00 SY
AC Road,2",4"rock,Q .over 2500SY RS-5 $ 19.00 SY
AC Road,3",4"rock,First 2500 SY RS-6 $ 23.30 SY 130 3,029.00 1385 32,270.50
AC Road,3",4"rock,Q .over 2500 SY RS-7 $ 21.00 SY
AC Road,5",First 2500 SY RS-8 $ 27.60 SY
AC Road,5",Qty.Over 2500 SY RS-9 $ 25.00 SY
AC Road,6",First 2500 SY RS-1 $ 33.10 SY
AC Road,6",Qt .Over 2500 SY RS-11 $ 30.00 SY
Asphalt Treated Base,4"thick RS-1 $ 20.00 SY
Gravel Road,4"rock,First 2500 SY S-1 $ 15.00 SY
Gravel Road,4"rock,Qt .over 2500 SY RS-1 $ 8.50 SY
PCC Road,5",no base,over 2500 SY RS-1 $ 27.00 SY
PCC Road, 6",no base,over 2500 SY RS-1 $ 25.50 SY
Thickened Edge RS-1 $ 8.60 LF
Page 5 of 9 SUBTOTAL 3,029.00 32,270.50
Unit prices updated: 02/12/02
'KCC 27A authorizes only one bond reduction. Version: 11/26/08
KC Bond Quantiry Worksheet-10-29-2012 Report Date: 10/29/2012
- --- --_ _. _� ---
Site (mprovement Bond Quantity Worksheet We� ,�'°v�°°�
�
Existing Futurc Public Private Bond Reduction*
Right-of-way Right of Way Improvements
&Drainage Facilities Quant.
Unit Price Unit Quant. Cost CJuanL Cost �uant CosC' Complete Cost
� ,;� �u i
Access Road,R/D D-1 $ 21.00 SY
Bollards-fixed D-2 $ 240.74 Each
Bollards-removable D-3 $ 452.34 Each
`(CBs include frame and lid)
CB Type I D-4 $ 1,257.64 Each 1 1,257.64 5 6,288.20 2 2,515.28
CB Type IL D-5 $ 1,433.59 Each
CB Type II,48"diameter D-6 $ 2,033.57 Each 4 8,134.28
for additional depth over 4' D-7 $ 436.52 FT 22 9,603.44
CB T pe II,54"diameter D-8 $ 2,192.54 Each
for additional de th over 4' D-9 $ 486.53 FT
CB T e II,60"diameter D-10 $ 2,351.52 Each
for additional depth over 4' D-11 $ 536.54 FT
CB Type II,72"diarneter D-12 $ 3,212.64 Each
for additional de th over 4' D-13 $ 692.21 FT
�hrough-curb Inlet Framework(Add) D-14 $ 366.09 Each
Cieanout,PVC,4" D-15 $ 130.55 Each 25 3,263.75
Cieanout,PVC,6" D-16 $ 174.90 Each
Cleanout,PVC,8" D-17 $ 224.19 Each
Culvert,PVC,4" D-18 $ 8.64 LF 878 7,585.92
rulvert,PVC,6" D-19 $ 12.60 LF 211 2,658.60
Culvert,PVC, 8" D-20 $ 13.33 LF
Culvert,PVC, 12" D-21 $ 21.77 LF
Culvert,CMP,8" D-22 $ 17.25 LF
Culvert,CMP, 12" D-23 $ 26.45 LF
Culvert,CMP, 15" D-24 $ 32.73 LF
Culvert,CMP, 18" D-25 $ 37.74 LF
Culvert,CMP,24" D-26 $ 53.33 LF
Culvert,CMP,30" D-27 $ 71.45 LF
Culvert,CMP,36" D-28 $ 112.11 LF
Culvert,CMP,48" D-29 $ 140.83 LF
Culvert,CMP,60" D-30 $ 235.45 LF
Culvert,CMP,72" D-31 $ 302.58 LF
Page 6 of 9 SUBTOTAL 1,257.64 24,025.92 16,023.55
Unit prices updated: 02/12/02
'KCC 27A authorizes only one bond reduction. Version: 11/26/08
KC Bond Quantity Worksheet-10-29-2012 RepOrt Date: 10/29/2012
_ -- -
Site Improvement Bond Quantity Worksheet -- � '"� '�'°�°°a -
Existing Future Public Private Bond Reduction* `
Right-of-way Right of Way Improvements
DRAINAGE CONTINUED &Drainage Facilities Cluant
No. Unil Price Unit (�uanl. CosC C2uant. Cost Quant: Cost Complete Cost
--
-- ---
--- _ --
Culvert,Concretf:,8" D-32 $ 21.02 LF
Culvert,Concrete, 12" D-33 $ 30.05 LF
Culvert,Concrete, 15" D-34 $ 37.34 LF
Culvert,Concrete, 18" D-35 $ 44.51 LF
Culvert,Concrete,24" D-36 $ 61.07 LF
Culvert,Concrete,30" D-37 $ 104.18 LF
Culvert,Concrete,36" D-38 $ 137.63 LF
Culvert,Concrete,42" D-39 $ 158.42 LF
Culvert,Concrete,48" D-40 $ 175.94 LF
Culvert,CPP,6" D-41 $ 10.70 LF
Culvert,CPP,8" D-42 $ 16.10 LF
Culvert,CPP, 12" D-43 $ 20.70 LF 664 13744.8
Culvert,CPP, 15" D-44 $ 23.00 LF
Culvert,CPP, 18" D-45 $ 27.60 LF
Culvert,CPP,24" D-46 $ 36.80 LF
Cutvert,CPP,30" D-47 $ 48.30 LF
Culvert,CPP,36" D-48 $ 55.20 LF
Ditchin D-49 $ 8.08 CY
Flow Dispersal Trench (1,436 base+) D-50 $ 25.99 LF �
French Drain (3'depth) D-51 $ 22.60 LF
Geotextile,laid in trench,pol propylene D-52 $ 2.40 SY
Infiltration ond testing D-53 $ 74.75 HR
Mid-tank Access Riser,48"dia, 6'deep D-54 $ 1,605.40 Each
Pond Overflow Spillway D-55 $ 14.01 SY
Restrictor/Oil Separator, 12" D-56 $ 1,045.19 Each 1 1045.19
Restrictor/Oil Se arator, 15" D-57 $ 1,095.56 Each
Restrictor/Oil Separator, 18" D-58 $ 1,146.16 Each
Riprap,placed D-59 $ 39.08 CY
Tank End Reducer(36"diameter) D-60 $ 1,000.50 Each
Trash Rack, 12" D-61 $ 211.97 Each
Trash Rack, 15" D-62 $ 237.27 Each
Trash Rack, 18" D-63 $ 268.89 Each
Trash Rack,21" D-64 $ 306.84 Each
Page 7 of 9 SUBTOTAL 14789.99
Unit prices updated: 02/12/02
`KCC 27A authorizes only one bond reduction. Ve�Si011: 11/26/08
KC E3ond Quantity Worksheet-10-29-2012 Report Date: 10/29/2012
-- — — —__
--- --- —- --
Site Improvement Bond Quantity Worksheet ---- �� "'�°a'g '�'°"`U`� --
Existing Future Public Private Bond Reduction" "
Right-of-way Right of Way Improvements
&Drainage Facilities Quant.
Unit Price Unit Quant. Price Quant. Cost Cluant. Cost Compiete Cost
Ih�.�� �... �w�� ... -..., .... .,...... . , .... . ._�... . �.F.. .r a--, . . .�.-- ,�.�. � . .
PARKING LOT SURFACING �� � "
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N o.
2"AC,2"to course rock&4"borrow PL-1 $ 21.00 SY
2"AC, 1.5" to course&2.5"base cou PL-2 $ 28.00 SY
4"select borrow PL-3 $ 4.55 SY
1.5"top course rock&2.5"base course PL-4 $ 11.41 SY
U�M����,�, '����. ��.
Utili Pole(s)Relocation UP-1 Lum Sum
Street Light Poles w/Luminaires UP-2 Each 2
�. _ . ,�'�.�`�-' e _� � �� ��„�_
WRITEJN�I�'��INS� ,��,� .
.,� ��
(Such as detention/water quality vaults.) No.
Detention Vault WI-1 � EA 1 145,000.00
Concrete Inlets Yard Drain) WI-2 $ 875.00 EA 4 3,500.00
D.I.Pipe-8-inch diameter WI-3 $ 25.50 LF 42 1071 60 1,530.00
WI-4
WI-5
WI-6
WI-7
WI-8
WI-9
wi-io
SUBTOTAL 1,071.00 146,530.00 3,500.00
SUBTOTAL(SUM ALL PAGES): 24,880.95 249,421.27 75,911.55
30%CONTINGENCY&MOBILIZATION: 7,464.28 74,826.38 22,773.46
GRANDTOTAL: 32,345.23 324,247.66 98,685.01
COLUMN: B C D E
Page 8 of 9
Unit prices updated: 02/12/02
� 'KCC 27A authorizes only one bond reduction. Version: 11/26/08
KC Bond Quantity Worksheet-10-29-2012 Report Date: 10/29/2012
Web date: 12/02/2008 ,
Site Improvement Bond Quantity Worksheet
,
Original bond computations prepared by:
Name: Barry R. Constant, P.E. nate: 10/29/2012
PE Registration Number: 38764 Tel.#: 425-392-8055
F�rm Name: Concept Engineering, Inc.
Address: 455 Rainier Blvd. North, Issaquah, WA 98027 Project No: U-120093
ROAD IMPROVEMENTS&DRAINAGE FACILITIES FINANCIAL GUARANTEE REQUIREMENTS
PERFORMANCE BOND' PUBLIC ROAD&DRAINAGE
AMOUNT BOND'AMOUNT MAINTENANCE/DEFECT BOND'
REQUIRED AT RECORDING OR
Stabilization/Erosion Sediment Control (ESC) (A) $ 18,192.9 TEMPORARY OCCUPANCY"*
Existing Right-of-Way Improvements (B) $ 32,345.2
Future Public Right of Way&Drainage Facilities (C) $ 324,247.7
Private Improvements (D) $ 98,685.0
Calculated Quantity Completed (E) $ -
Total Right-of Way and/or Site Restoration Bond'/`* (A+B) $ 50,538.1
(First$7,500 of bond*shall be cash.)
Performance Bond*Amount (A+B+C+D) = TOTAL (T) $ 473,470.8 T x 0.30 $ 142,041.2 OR
Minimum on amount is 00.
Reduced Performance Bond* Total "' (T-E) $ 473,470.8
Use larger o x o or -
(B+c)X
Maintenance/Defect Bond" Total 0.25 = $ 89,148.2
NAM[O�PERSON PREPARING BOND`REDUCTION: Date:
"NOTE: The word"bond"as used in this document means a financial guarantee acceptable to King Counry.
"NOTE: KCC 27A authorizes right of way and site restoration bonds to be combined when both are required.
The restoration requirement shall include the total cost for all TESC as a minimum,not a maximum. In addition,corrective work,both on-and off-site needs to be included.
Quantities shall reflect worse case scenarios not just minimum requirements. For example,if a salmonid stream may be damaged,some estimated costs for restoration
needs to be reFlected in this amount. The 30%contingency and mobilization costs are computed in this quantity.
"'NOTE: Per KCC 27A,total bond amounts remaining after reduction shall not be less than 30%of the original amount(T)or as revised by major design changes.
REQUIRFD ROND"AMOUNTS ARE SUBJECT TO REVIEW AND MODIFICATION BY DDES
Page 9 of 9 Unit prices updated: 02/12/02
Check out the DDES Web site at www.kingcounty.aov/�zermits Version: 11/26/08
KC Bond Quantity Worksheet-10-29-2012 Report Date: 10/29/2012
y �
I
� Bremerton Townhomes January 2013
Technical Information Report
1
APPENDIX G
PERMEABLE PAVING CALCULATIONS
1
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� P:/31125,'engineering/.../word/TIR?Final-Revised TIR 10-26-2012.doc
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� Bremerton Townhomes January 2013
� Technical Information Report
PERNIEABLE PAVING, DRIVEWAYS & WALHING PATH AREAS
� 1
� Area Len th (ft) X Width ft) Total
A 57 X 12 684
� —I B 57 X 12 684
C 97 X 12 1164
D 97 X 12 1164
� E 57 X 12 684
I� F 57 X 12 684
( G 68 X 12 816
H 41 X 12 492
I 64 X 20 1280
� Unit Drivewa s
1 16 X 5.5 88
2 16 X 5.5 88
I 3 16 X 5.5 88
, 4 16 X 5.5 88
5 16 X 5.5 88
� I 6 22 X 18 396
7 17X4 68 �
8 17 X 7 � 119
� 9 17 X 7 119
10 17 X 7 119 '
11 17 X 7 119
� 12 17 X 7 119
13 14 X 18 252
14 16 X 18 288 �
I 15 16 X 14 224
16 � 16 X 14 224 �
! 17 16 X 18 288 '
� 18 12 X 18 216
19 20 X 7 140
� 20 20 X 7 140
21 20 X 8.5 170
22 20 X 6 120
� 23 20 X 8.5 170
�
' 24 20 X 6 120
25 18 X 5.5 99 i
� 26 18 X 5.5 99
i
Walkin ath SW to Door Av . size 12 X 5 1525
Walkin ath to South 105 X 5 -260*)
i 13,622 SF
13,622 SF > 12196 SF (0.28-acre)= OKAY
i See Exhibit 1VIap below, all hatched areas total to amount above. 0.28-acres figure is credit
� sho��m in vault calcs. * The—260 is acc�ounted for in the drive«-ays for lots 13, 14 and 15
� � P:r 31125 i eneineering I...,` word; TIR -Final-Re��sed TIR 10-26-2012.doc