HomeMy WebLinkAboutF_Vantage Glen Storm Drain Extension_Technical Information Report_171127
Abbreviated Technical Information Memorandum
(For Repair and Maintenance)
Vantage Glen Mobile Home Park
18100 107th Street S.E.
Renton, Washington 98055
Parcel No. 322305-9361
Prepared for:
King County Housing Authority
Attn: Hugh Watkinson
600 Andover Park West
Seattle, WA 98188-3326
October 26, 2017
Innova Architects Job No. 17-030
Prepared by: Jason Hein
Reviewed by: Paul McCormick
“I hereby state that this Abbreviated Technical Information Report for the Vantage Glen Mobile Home
Park, Renton, Washington has been prepared by me or under my supervision and meets the standard of
care and expertise which is usual and customary in this community for professional engineers. I
understand that the City of Renton does not and will not assume liability for the sufficiency, suitability, or
performance of drainage facilities prepared by me.”
10/26/
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7
DEVELOPMENT ENGINEERING
IFitz-James 11/21/2017
SURFACE WATER UTILITY
rstraka 11/27/2017
2
Section 1 – Project Description
The proponent, King County Housing Authority (KCHA), wishes to provide maintenance and
repair to their existing drainage system located on Parcel No.322305-9361. We expect that the
scope of work falls within guidelines of maintenance and repair. This Abbreviated Technical
Information Memorandum (For Repair and Maintenance) is submitted with the Civil Construction
Permit plan package, and is prepared to address the maintenance concerns that exist at the
site.
The project site is located at 104th Avenue SE, as shown on the Site Map (Exhibit 1), which
follows. The site is located within the Vantage Glen development at 18100 107th Place S.E in
Renton, Washington. The proposed work scope is limited to connecting roof drains at Lots 111,
112, 113, 114, 115 and 116 to the existing storm system, and installing two catchbasins and 10-
inch storm line on the east side of 104th Avenue SE, near the point of tangent of the cul-de-sac.
This work is proposed to address ponding on Lots 111, 112, 113, 114, 115 and 116 and on
104th Avenue SE near Lot 111, as shown on the photographs provided as Exhibits 2, 3 and 4.
The original design intent was for lot drainage to flow to the eastern curb line of 104th Avenue
SE. Cul-de-sac drainage was intended to flow to the south along the eastern curb line to a Type
1 catchbasin that conveys drainage to a detention pond, as shown in Exhibit 5. However,
grading in the asbuilt condition allows drainage to pond at the cul-de-sac near Lot 111, and roof
drainage at Lots 111, 112, 113, 114, 115, and 116 pond in the yards. The work proposed is
intended to repair the existing ponding condition.
Section 2 – Existing Site Conditions
As noted in the section above, there is ponding in the yards of Lots 111, 112, 113, 114, 115 and
116, primarily due to roof drainage and low points in the lot yards. Downspouts at these lots are
not tight-lined, and drainage flows from the downspouts to low points within the yards. There is
a low point in the cul-de-sac at 104th Avenue SE, near the point of tangent at the eastern curb
line, causing ponding, as shown in the site photographs, provided as Exhibits 2, 3 and 4. The
original design plans show that the drainage intent was for cul-de-sac drainage to flow to the
south at 1-percent, and to the east at 0.5-percent slope to the curb line. 104th Avenue SE is a
super elevated road section, sloping from the west to the east. Lot drainage, per the original
design, was intended to slope to the roadway curb line.
Section 3 – Adjacent Areas
The site is located between 105th Pl SE to the east and Wells Avenue S to the west, as shown
on the Site Plan provided as Exhibit 1. The entrance to the development, Vantage Glen, is via
SE 180th Street, which is west of the intersection of SE 180th Street and Highway 515.
Section 4 – Proposed Solution
This project proposes only maintenance and repair work. No new impervious or pervious areas
are proposed. Work is limited to utility trenching and installation of 225 lineal feet of 10-inch
storm line on the south side of 104th Avenue SE cul-de-sac, in order to alleviated ponding in the
roadway. Work also includes the installation of 397 lineal feet of 6-inch roof drain and cleanouts
to tight-line roof drainage to alleviate ponding in the yards at Lots 111, 112, 113, 114, 115 and
3
116. The proposed 10-inch storm line in the roadway (104th Avenue SE) will connect to an
existing Type 1 catchbasin. This existing catchbasin has a 12-inch perforated outlet pipe that
conveys drainage to the south to an existing detention pond. Roof drainage from Lots 111, 112,
113, and a portion of the roof drainage for Lots 114, 115 and 116, is proposed to be tight-lined
and connected to the new 10-inch storm line and to an existing 8-inch storm line, which is
located along the eastern side of Lots 114, 115, and 116, as shown on Exhibit 6. Storm line
trenching in the roadway (104th Avenue SE) results in 1,780 square feet of asphalt patching;
and, utilities trenching for the roof drains in the lots results in 963 square feet of grass re-
seeding. Proposed asphalt patching results in less than the 2,000 square foot threshold for
replaced impervious surface, and the project results in less than the 7,000 square foot threshold
of land disturbance. Also as noted above, drainage from the project site area drains to an
existing detention pond, which was sized for the development (Vantage Glen), including
drainage from the subject site area.
The new 10-inch storm line was checked for capacity to flow the 25-year and the 100-year, 24-
hour peak storm event. Flows were determined (for the 25- and 100-year events) using the
Rational Method, as required by the City of Renton. The WSDOT spreadsheet, based on the
Rational Method, was used to calculate the flow through each pipe segment. Both the 25-yar
and 100-year resulting flows were calculated. However, only the 25-year event was used to
check pipe capacity, as required by the City of Renton’s storm water manual.
A tributary drainage map was prepared, which shows the onsite and offsite tributary areas that
ultimately flow to the proposed 10-inch line. Capacity calculations, and velocity checks, are also
provided for two existing 8-inch PVC pipes that are upstream of the proposed 10-inch pipe.
Offsite flows were calculated (spreadsheet calculations provided in Exhibit 6) and these tributary
flows are added in Column 12 of the “Storm Sewer Design” spreadsheets in Exhibit 6. A Tc
minimum of 6.3 was used, per the City’s storm manual, for determining the offsite tributary
flows. In the conveyance calculation spreadsheets (“Storm Sewer Design”), which were taken
from WSDOT’s Hydraulic Manual, a Tc minimum of 5 minutes was used. The rainfall
coefficients (for the 25- and 100-year MRI coefficients) were also taken from WSDOT’s
Hydraulic Manual. Coefficient figures and isopluvial maps are provided in Exhibit 6. The
resulting flows for the proposed 10-inch line and the two existing 8-inch lines show that these
pipe are not flowing full in the 25-year storm (nor in the 100-year storm). Therefore to determine
the minimum velocity given the actual flow with the pipes partially full, flow calculations were
done for a partially full condition, and the resulting velocities determined. Velocities in the 10-
inch line, determined for each segment, range from 2.7 fps to 3.44 fps. For the existing 8-inch
PVC pipes, the velocity ranges between 2.59 fps to 3.15 fps. Although the calculated pipe
velocities fall below the 3.0 fps recommended by the 2017 City of Renton Surface Water Design
Manual (Table 4.2.1.A1), the subject storm system is a private storm system that is maintained
by King County Housing Authority. In addition, pipe velocity of less than 3.0 fps is an existing
condition. See Exhibit 7 for storm conveyance calculation.
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EXIBIT 1
SITE MAP
5
EXHIBIT 2
YARD PONDING AT LOTS
6
EXHIBIT 3
104TH AVENUE SE PONDING (EAST CURB LINE. LOOKING WEST)
7
EXHIBIT 4
104TH AVENUE SE PONDING (EAST CURB LINE, LOOKING NORTH)
8
EXHIBIT 5
ORIGINAL DESIGN PLANS – VANTAGE GLEN DEVELOPMENT
12
EXHIBIT 6
PROPOSED DESIGN PLANS
SURFACE WATER STANDARD PLAN NOTES
SURFACE WATER STANDARD PLAN NOTES
1.THESE NOTES SHALL APPEAR ON PROJECTS FOR THE SURFACE WATER UTILITY.
2.BEFORE ANY CONSTRUCTION OR DEVELOPMENT ACTIVITY OCCURS, A PRE-CONSTRUCTION MEETING MUST BE HELD
BETWEEN THE CITY OF RENTON PLAN REVIEW SECTION AND THE APPLICANT.
3.ALL DESIGN AND CONSTRUCTION SHALL BE IN ACCORDANCE WITH THE RENTON MUNICIPAL CODE (RMC), THE LATEST EDITION
OF THE STANDARD SPECIFICATION FOR ROAD, BRIDGE AND MUNICIPAL CONSTRUCTION PREPARED BY WSDOT AND THE
AMERICAN PUBLIC WORKS ASSOCIATION (APWA) AS AMENDED BY THE CITY OF RENTON PUBLIC WORKS DEPARTMENT. IT
SHALL BE THE SOLE RESPONSIBILITY OF THE APPLICANT AND THE PROFESSIONAL CIVIL ENGINEER TO CORRECT ANY ERROR,
OMISSIONS OR VARIATION FROM THE ABOVE REQUIREMENTS FOUND IN THIS PLANS. ALL CORRECTIONS SHALL BE AT NO
ADDITIONAL COST TO THE CITY.
4.APPROVAL OF THIS ROAD, GRADING, PARKING AND DRAINAGE PLAN DOES NOT CONSTITUTE AN APPROVAL OF ANY OTHER
CONSTRUCTION (E.G. DOMESTIC WATER CONVEYANCE, SEWER CONVEYANCE, GAS, ELECTRIC, ETC.) THE SURFACE WATER
DRAINAGE SYSTEM SHALL BE CONSTRUCTED ACCORDING TO THE APPROVED PLANS, WHICH ARE ON FILE IN WITH THE CITY.
ANY DEVIATION FROM THE APPROVED PLANS WILL REQUIRE WRITTEN APPROVAL FROM THE CITY OF RENTON PUBLIC WORKS
DEPARTMENT, SURFACE WATER UTILITY SECTION.
5.A COPY OF THESE APPROVED PLANS MUST BE ON THE JOB SITE WHENEVER CONSTRUCTION IS IN PROGRESS.
6.GRADING ACTIVITIES (SITE ALTERATION) ARE LIMITED TO THE HOURS OF 7 A.M. TO 7 P.M. MONDAY THROUGH SATURDAY AND
NO WORK ON SUNDAY IS ALLOWED, UNLESS OTHERWISE APPROVED WITH A WRITTEN DECISION BY THE CITY OF RENTON.
7.,76+$//%(7+($33/,&$17¶6&2175$&725¶65(63216,%,/,7<722%7$,1$//&216758&7,21($6(0(1761(&(66$5<
BEFORE INITIATING OFF-SITE WORK. EASEMENTS REQUIRE CITY REVIEW AND APPROVAL PRIOR TO CONSTRUCTION.
8.FRANCHISED UTILITIES OR OTHER INSTALLATIONS THAT ARE NOT SHOWN ON THESE APPROVED PLANS SHALL NOT BE
CONSTRUCTED UNLESS AN APPROVED SET OF PLANS THAT MEET ALL REQUIREMENTS OF CHAPTER 4 OF THE SURFACE
WATER DESIGN MANUAL ARE SUBMITTED TO THE CITY OF RENTON.
9.DATUM SHALL BE NAVD 88 UNLESS OTHERWISE APPROVED BY THE CITY OF RENTON. REFERENCE BENCHMARK AND
ELEVATIONS ARE NOTED ON THE PLANS.
10.ANY DEWATERING SYSTEM NECESSARY FOR THE CONSTRUCTION OF STORMWATER FACILITIES MUST BE SUBMITTED TO THE
CITY FOR REVIEW AND APPROVAL.
11.ALL UTILITY TRENCHES AND ROADWAY SUBGRADE SHALL BE BACKFILLED AND COMPACTED TO 95 PERCENT DENSITY,
STANDARD PROCTOR.
12.OPEN CUTTING OF EXISTING ROADWAYS FOR NON-FRANCHISED UTILITY OR STORM DRAINAGE WORK IS NOT ALLOWED
UNLESS SPECIFICALLY APPROVED BY THE CITY OF RENTON AND NOTED ON THESE APPROVED PLANS. ANY OPEN CUT SHALL
BE RESTORED IN ACCORDANCE WITH THE CITY OF RENTON TRENCH RESTORATION STANDARDS.
13.ALL SEDIMENTATION/EROSION FACILITIES MUST BE IN OPERATION PRIOR TO CLEARING AND BUILDING CONSTRUCTION, AND
THEY MUST BE SATISFACTORILY MAINTAINED UNTIL CONSTRUCTION IS COMPLETED AND THE POTENTIAL FOR ON-SITE
EROSION HAS PASSED.
14.ALL RETENTION/DETENTION FACILITIES MUST BE INSTALLED AND IN OPERATION PRIOR TO OR IN CONJUNCTION WITH ALL
CONSTRUCTION ACTIVITY UNLESS OTHERWISE APPROVED BY THE PUBLIC WORKS DEPARTMENT, SURFACE WATER UTILITY
SECTION.
15.ALL PIPE AND APPURTENANCES SHALL BE LAID ON A PROPERLY PREPARED FOUNDATION IN ACCORDANCE WITH THE
CURRENT STATE OF WASHINGTON STANDARD SPECIFICATION FOR ROAD AND BRIDGE CONSTRUCTION. THIS SHALL INCLUDE
NECESSARY LEVELING OF THE TRENCH BOTTOM OR THE TOP OF THE FOUNDATION MATERIAL, AS WELL AS PLACEMENT AND
COMPACTION OF REQUIRED BEDDING MATERIAL, TO UNIFORM GRADE SO THAT THE ENTIRE LENGTH OF THE PIPE WILL BE
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EXCEPTION OF PVC PIPE.
16.STEEL PIPE SHALL BE ALUMINIZED, OR GALVANIZED WITH ASPHALT TREATMENT #1 OR BETTER INSIDE AND OUTSIDE.
17.ALL DRAINAGE STRUCTURES, SUCH AS CATCH BASINS AND MANHOLES SHALL HAVE SOLID LOCKING LIDS. ALL DRAINAGE
STRUCTURES ASSOCIATED WITH A PERMANENT RETENTION/DETENTION FACILITY SHALL HAVE SOLID LOCKING LIDS.
18.BUILDING AND OTHER STRUCTURES SHALL BE PLACED IN ACCORDANCE WITH TABLE 4.1 EASEMENT WIDTHS AND BUILDING
SETBACKS LINES.
19.ALL CATCH BASIN GRATES SHALL BE DEPRESSED 0.10 FEET BELOW PAVEMENT LEVEL.
20.ALL DRIVEWAY CULVERTS LOCATED WITHIN CITY OF RENTON RIGHT-OF-WAY SHALL BE OF SUFFICIENT LENGTH TO PROVIDE A
MINIMUM 3:1 SLOPE FROM THE EDGE OF THE DRIVEWAY TO THE BOTTOM OF THE DITCH. ROCK FOR EROSION PROTECTION OF
ROADSIDE DITCHES, WHERE REQUIRED, SHALL BE OF SOUND QUARRY ROCK PLACED TO A DEPTH OF ONE (1) FOOT AND
MUST MEET THE FOLLOWING SPECIFICATIONS:
4 - 8 INCH ROCK / 40 - 70% PASSING;
2 - 4 INCH ROCK / 30 - 40% PASSING; AND
LESS THAN 2 INCH ROCK / 10 - 20% PASSING.
21.ALL BUILDING DOWNSPOUTS AND FOOTING DRAINS SHALL BE CONNECTED TO THE STORM DRAINAGE SYSTEM, UNLESS
APPROVED BY THE CITY PLAN REVIEWER OR SURFACE WATER UTILITY SECTION. AN ACCURATELY DIMENSIONED, CERTIFIED
AS-BUILT DRAWING OF THIS DRAINAGE SYSTEM WILL BE SUBMITTED TO THE CITY UPON COMPLETION.
22.DRAINAGE OUTLETS (STUB-OUTS) SHALL BE PROVIDED FOR EACH INDIVIDUAL LOT, EXCEPT FOR THOSE LOTS APPROVED FOR
INFILTRATION BY THE CITY. STUB-OUTS SHALL CONFORM TO THE FOLLOWING:
A. EACH OUTLET SHALL BE SUITABLY LOCATED AT THE LOWEST ELEVATION ON THE LOT, SO AS TO
SERVICE ALL FUTURE ROOF DOWNSPOUTS AND FOOTING DRAINS, DRIVEWAYS, YARD DRAINS,
AND ANY OTHER SURFACE OR SUBSURFACE DRAINS NECESSARY TO RENDER THE LOTS SUITABLE
FOR THEIR INTENDED USE. EACH OUTLET SHALL HAVE FREE-FLOWING, POSITIVE DRAINAGE TO
AN APPROVED STORMWATER CONVEYANCE SYSTEM OR TO AN APPROVED OUTFALL LOCATION.
B. OUTLETS ON EACH LOT SHALL BE LOCATED WITH A FIVE-FOOT-HIGH, 2" X 4" STAKE MARKED
"STORM" OR "DRAIN". THE STUB-OUT SHALL EXTEND ABOVE SURFACE LEVEL, BE VISIBLE, AND
BE SECURED TO THE STAKE.
C. PIPE MATERIAL SHALL CONFORM TO UNDERDRAIN SPECIFICATIONS DESCRIBED IN CHAPTER 4 OF
THE SURFACE WATER DESIGN MANUAL AND, IF NON-METALLIC, THE PIPE SHALL BE PLACED IN
A TRENCH WITH A TRACING WIRE ABOVE OR OTHER ACCEPTABLE DETECTION.
D. PRIVATE DRAINAGE EASEMENTS ARE REQUIRED FOR DRAINAGE SYSTEMS DESIGNED TO
CONVEY FLOWS THROUGH INDIVIDUAL LOTS.
E. THE APPLICANT/CONTRACTOR IS RESPONSIBLE FOR COORDINATING THE LOCATIONS OF ALL STUBOUT
CONVEYANCE LINES WITH RESPECT TO OTHER UTILITIES (E.G. POWER, GAS, TELEPHONE,
TELEVISION).
F. ALL INDIVIDUAL STUB-OUTS SHALL BE PRIVATELY OWNED AND MAINTAINED BY THE LOT HOME
OWNER.
G. STORM DRAINAGE PIPE SYSTEMS SHALL NOT PENETRATE BUILDING FOUNDATIONS, EXCEPT FOR
SUMP PUMP DISCHARGE LINES USED TO DRAIN CRAWL SPACES, PROVIDED THE SUMP PUMP SYSTEM INCLUDES
BACKFLOW PREVENTION OR A CHECK VALVE.
23.ALL DISTURBED PERVIOUS AREAS (COMPACTED, GRADED, LANDSCAPED, ETC.) OF THE DEVELOPMENT SITE MUST
DEMONSTRATE ONE OF THE FOLLOWING: THE EXISTING DUFF LAYER SHALL BE STAGED AND REDISTRIBUTED TO MAINTAIN
THE MOISTURE CAPACITY OF THE SOIL, OR; AMENDED SOIL SHALL BE ADDED TO MAINTAIN THE MOISTURE CAPACITY.
24.PROOF OF LIABILITY INSURANCE SHALL BE SUBMITTED TO THE CITY PRIOR TO CONSTRUCTION PERMIT ISSUANCE.
25.ISSUANCE OF THE BUILDING OR CONSTRUCTION PERMITS BY THE CITY OF RENTON DOES NOT RELIEVE THE OWNER OF THE
CONTINUING LEGAL OBLIGATION AND/OR LIABILITY CONNECTED WITH STORM SURFACE WATER DISPOSITION. FURTHER, THE
CITY OF RENTON DOES NOT ACCEPT ANY OBLIGATION FOR THE PROPER FUNCTIONING AND MAINTENANCE OF THE SYSTEM
PROVIDED DURING CONSTRUCTION.
26.THE CONTRACTOR SHALL BE RESPONSIBLE FOR PROVIDING ADEQUATE SAFEGUARD, SAFETY DEVICES, PROTECTIVE
EQUIPMENT,FLAGGERS, AND ANY OTHER NEEDED ACTIONS TO PROTECT THE LIFE, HEALTH, AND SAFETY OF THE PUBLIC, AND
TO PROTECT PROPERTY IN CONNECTION WITH THE PERFORMANCE OF WORK. ANY WORK WITHIN THE TRAVELED
RIGHT-OF-WAY THAT MAY INTERRUPT NORMAL TRAFFIC FLOW SHALL REQUIRE A TRAFFIC CONTROL PLAN APPROVE BY THE
PUBLIC WORKS DEPARTMENT, TRANSPORTATION SYSTEMS DIVISION. ALL SECTIONS OF THE WSDOT STANDARD
SPECIFICATIONS 1-07-23 TRAFFIC CONTROL SHALL APPLY.
27.PROJECT LOCATED WITHIN THE AQUIFER PROTECTION AREA (APA) SHALL COMPLY WITH SPECIAL REQUIREMENT #6 OF THE
SURFACE WATER DESIGN MANUAL AND AQUIFER PROTECTION REGULATIONS (RMC 4-3-050).
EROSION CONTROL NOTES
1.THESE NOTES SHALL APPEAR FOR ALL PROJECTS - SITE IMPROVEMENTS, SURFACE WATER UTILITY, WASTEWATER
UTILITY, WATER UTILITY, AND TRANSPORTATION PLANS:
2.BEFORE ANY CONSTRUCTION OR DEVELOPMENT ACTIVITY OCCURS, A PRE-CONSTRUCTION MEETING MUST BE
HELD WITH THE CITY OF RENTON, PUBLIC WORKS DESIGN ENGINEER.
3.THE BOUNDARIES OF THE CLEARING LIMITS AND AREAS OF VEGETATION PRESERVATION AS PRESCRIBED ON THE
PLAN(S) SHALL BE CLEARLY FLAGGED BY SURVEY TAPE OR FENCING IN THE FIELD PRIOR TO CONSTRUCTION IN
ACCORDANCE WITH APPENDIX D OF THE SURFACE WATER DESIGN MANUAL AND OBSERVED DURING
CONSTRUCTION. DURING THE CONSTRUCTION PERIOD, NO DISTURBANCE BEYOND THE CLEARING LIMITS SHALL BE
PERMITTED. THE CLEARING LIMITS SHALL BE MAINTAINED BY THE APPLICANT/ESC SUPERVISOR FOR THE DURATION
OF CONSTRUCTION.
4.STABILIZED CONSTRUCTION ENTRANCES SHALL BE INSTALLED AT THE BEGINNING OF CONSTRUCTION AND
MAINTAINED FOR THE DURATION OF THE PROJECT. ADDITIONAL MEASURES, SUCH AS CONSTRUCTED WHEEL WASH
SYSTEMS OR WASH PADS, MAY BE REQUIRED TO ENSURE THAT ALL PAVED AREAS ARE KEPT CLEAN AND TRACK
OUT TO ROAD RIGHT OF WAY DOES NOT OCCUR FOR THE DURATION OF THE PROJECT.
5.ALL REQUIRED SEDIMENTATION/EROSION CONTROL FACILITIES MUST BE CONSTRUCTED AND IN OPERATION PRIOR
TO LAND CLEARING AND/OR CONSTRUCTION TO PREVENT TRANSPORTATION OF SEDIMENT TO SURFACE WATER,
DRAINAGE SYSTEMS AND ADJACENT PROPERTIES. ALL EROSION AND SEDIMENT FACILITIES SHALL BE MAINTAINED
IN A SATISFACTORY CONDITION UNTIL SUCH TIME THAT CLEARING AND/OR CONSTRUCTION IS COMPLETE AND
POTENTIAL FOR ON-SITE EROSION HAS PASSED. THE IMPLEMENTATION, MAINTENANCE, REPLACEMENT AND
ADDITIONS TO EROSION/SEDIMENTATION CONTROL SYSTEMS SHALL BE THE RESPONSIBILITY OF THE PERMITEE.
6.THE EROSION AND SEDIMENTATION CONTROL SYSTEMS DEPICTED ON THIS DRAWING ARE INTENDED TO BE
MINIMUM REQUIREMENTS TO MEET ANTICIPATED SITE CONDITIONS. AS CONSTRUCTION PROGRESSES AND
UNEXPECTED OR SEASONAL CONDITIONS DICTATE, THE PERMITEE SHALL ANTICIPATE THAT MORE EROSION AND
SEDIMENTATION CONTROL FACILITIES WILL BE NECESSARY TO ENSURE COMPLETE SILTATION CONTROL ON THE
PROPOSED SITE. DURING THE COURSE OF CONSTRUCTION, IT SHALL BE THE OBLIGATION AND RESPONSIBILITY OF
THE PERMITEE TO ADDRESS ANY NEW CONDITIONS THAT MAY BE CREATED BY THE ACTIVITIES AND TO PROVIDE
ADDITIONAL FACILITIES, OVER AND ABOVE MINIMUM REQUIREMENTS, AS MAY BE NEEDED, TO PROTECT ADJACENT
PROPERTIES AND WATER QUALITY OF THE RECEIVING DRAINAGE SYSTEM.
7.APPROVAL OF THIS PLAN IS FOR EROSION/SEDIMENTATION CONTROL ONLY. IT DOES NOT CONSTITUTE AN
APPROVAL OF STORM DRAINAGE DESIGN, SIZE NOR LOCATION OF PIPES, RESTRICTORS, CHANNELS, OR RETENTION
FACILITIES.
8.ANY AREAS OF EXPOSED SOILS, INCLUDING ROADWAY EMBANKMENTS, THAT WILL NOT BE DISTURBED FOR TWO
DAYS DURING THE WET SEASON (OCTOBER 1 ST THROUGH MARCH 30TH) OR SEVEN DAYS DURING THE DRY SEASON
(APRIL 1ST THROUGH SEPTEMBER 30TH) SHALL BE IMMEDIATELY STABILIZED WITH THE APPROVED ESC COVER
METHODS (E.G., SEEDING, MULCHING, PLASTIC COVERING, ETC.).
9.WET SEASON SEASONAL EROSION AND SEDIMENT CONTROL REQUIREMENTS APPLY TO ALL CONSTRUCTION SITES
CLEARING BETWEEN OCTOBER 1 ST AND MARCH 30TH INCLUSIVE, UNLESS OTHERWISE APPROVED BY THE CITY
THROUGH AN ADJUSTMENT PROCESS.
10.COVER MEASURES WILL BE APPLIED IN CONFORMANCE WITH APPENDIX D OF THE SURFACE WATER DESIGN
MANUAL.
11.ANY AREA NEEDING ESC MEASURES, NOT REQUIRING IMMEDIATE ATTENTION, SHALL BE ADDRESSED WITHIN SEVEN
(7) DAYS.
12.THE ESC FACILITIES ON INACTIVE SITES SHALL BE INSPECTED AND MAINTAINED A MINIMUM OF ONCE A MONTH OR
WITHIN 24 HOURS FOLLOWING A STORM EVENT.
13.AT NO TIME SHALL MORE THAN ONE (1) FOOT OF SEDIMENT BE ALLOWED TO ACCUMULATE WITHIN A CATCH BASIN.
ALL CATCH BASINS AND CONVEYANCE LINES SHALL BE CLEANED PRIOR TO PAVING. THE CLEANING OPERATION
SHALL NOT FLUSH SEDIMENT-LADEN WATER INTO THE DOWNSTREAM SYSTEM.
14.DURING THE TIME PERIOD OF OCTOBER 1 ST THROUGH MARCH 30TH, ALL PROJECT DISTRIBUTED SOIL AREAS
GREATER, THAT ARE TO BE LEFT UN-WORKED FOR MORE THAN 12 HOURS, SHALL BE COVERED BY MULCH,
SODDING OR PLASTIC COVERING.
15.ANY PERMANENT RETENTION/DETENTION FACILITY USED AS A TEMPORARY SETTLING BASIN SHALL BE MODIFIED
WITH THE NECESSARY EROSION CONTROL MEASURES AND SHALL PROVIDE ADEQUATE STORAGE CAPACITY. IF THE
PERMANENT FACILITY IS TO FUNCTION ULTIMATELY AS AN INFILTRATION SYSTEM, THE TEMPORARY FACILITY MUST
BE ROUGH GRADED SO THAT THE BOTTOM AND SIDES ARE AT LEAST THREE FEET ABOVE THE FINAL GRADE OF THE
PERMANENT FACILITY.
16.PRIOR TO THE BEGINNING OF THE WET SEASON (OCT. 1), ALL DISTURBED AREAS SHALL BE REVIEWED TO IDENTIFY
WHICH ONES CAN BE SEEDED IN PREPARATION FOR THE WINTER RAINS. DISTURBED AREAS SHALL BE SEEDED
WITHIN ONE WEEK OF THE BEGINNING OF THE WET SEASON.A SKETCH MAP OF THOSE AREAS TO BE SEEDED AND
THOSE AREAS TO REMAIN UNCOVERED SHALL BE SUBMITTED TO THE CITY OF RENTON FOR REVIEW.
17.ALL ESC MEASURES MUST BE REMOVED AFTER CONSTRUCTION ACTIVITY IS COMPLETE.HIGHWAY 167108TH AVE SE176TH
STREET
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VICINITY MAP
SITE
PROJECT
LOCATION
CONTACTS
DEVELOPER
KING COUNTY HOUSING AUTHORITY
HUGH WATKINSON
CAPITAL CONSTRUCTION PROJECT MANAGER
600 ANDOVER PARK WEST
SEATTLE, WA 98188
SURVEYOR
TRIAD
GREGORY T. JUNEAU, PLS
20300 WOODINVILLE SNOHOMISH
ROAD NE, SUITE A
WOODINVILLE, WA 98072
PH 425-415-2041
CIVIL ENGINEER
INNOVA ARCHITECTS
PAUL MCCORMIK, PE
950 PACIFIC AVENUE, SUITE 450
TACOMA, WA 98402
PH 253-572-4903
UTILITIES
WATER - SOOS CREEK WATER
AND SEWER DISTRICT
SEWER - SOOS CREEK WATER
AND SEWER DISTRICT
STORM - CITY OF RENTON
TELEPHONE - QWEST / CENTURY LINK
POWER - PUGET SOUND ENERGY
GAS - PUGET SOUND ENERGY
A PORTION OF THE SW 1/4 OF THE NE 1/4 OF SECTION 32, TOWNSHIP 23, RANGE 5 E., W.M.
CITY OF RENTON, KING COUNTY, WASHINGTON
KING COUNTY HOUSING AUTHORITY-VANTAGE GLEN MOBILE HOME PARK
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SITE DETAILS
ADDRESS:18102 107TH PL SE, RENTON, WA
PARCEL:322305-9361
ZONING:RESIDENTIAL
MANUFACTURED HOMES
GROSS SITE AREA: 6) $&5(6
PROJECT SITE AREA:6) $&5(6
AUTOCAD FILE
AUTOCAD DRAWING FILES ARE AVAILABLE FOR SITE
LAYOUT UPON REQUEST.
GENERAL NOTES TAKEN FROM SURVEY
1.) BOUNDARY LINES SHOWN ARE BASED ON RENTON SHORT PLAT #LUA-08-137-SHPL RECORDED IN VOLUME 268 OF
SURVEYS, PAGES 168-170, IN KING COUNTY, WASHINGTON.
2.) INSTRUMENTATION FOR THIS SURVEY WAS A TRIMBLE VX SPATIAL STATION. PROCEDURES USED IN THIS SURVEY
WERE FIELD TRAVERSE, MEETING OR EXCEEDING STANDARDS SET BY WAC 332-130-090.
3.) THE INFORMATION DEPICTED ON THIS MAP REPRESENTS THE RESULTS OF A SURVEY MADE IN MAY 2017 AND CAN
ONLY BE CONSIDERED AS INDICATING THE GENERAL CONDITION EXISTING AT THAT TIME.
4.) SANITARY SEWER AND STORM DRAINAGE FACILITIES HAVE BEEN ASBUILT THROUGH FIELD MEASUREMENTS OF
THE LOCATION OF THE ACCESS STRUCTURES, THE TOP ELEVATION OF THE STRUCTURES, AND THE INVERT
ELEVATIONS OF ANY PIPES ENTERING OR LEAVING THE STRUCTURES. IT IS STANDARD PRACTICE TO SHOW THE PIPES
CONNECTING THESE STRUCTURES AS STRAIGHT LINES. THIS IS ONLY AN ASSUMPTION AND THE ACTUAL LOCATION OF
THE PIPING MUST BE VERIFIED IN THE FIELD BY THE CONTRACTOR PRIOR TO ANY CONSTRUCTION.
5.) NO EASEMENTS, RESTRICTIONS OR RESERVATION OF RECORD WHICH WOULD BE DISCLOSED BY TITLE REPORT
ARE SHOWN.
6.) PIPE ELEVATIONS SHOWN FOR INACCESSIBLE YARD DRAIN STRUCTURES ARE APPROXIMATE TO THE TENTH OF A
FOOT AND SHOULD BE FIELD VERIFIED PRIOR TO ANY CONSTRUCTION ACTIVITY AS NECESSARY.
BASIS OF BEARING
RENTON SHORT PLAT #LUA-08-137-SHPL
RECORDED IN VOLUME 268 OF SURVEYS, PAGES
168-170, IN KING COUNTY, WASHINGTON
LEGAL DESCRIPTION
LOT 2 AND TRACT C-2 OF RENTON SHORT PLAT
#LUA-08-137-SHPL RECORDED IN VOLUME 268 OF SURVEYS,
PAGES 168-170, IN KING COUNTY, WASHINGTON
HORIZONTAL DATUM
NAD83/91 - WASHINGTON NORTH ZONE BASED
ON TIES TO CITY OF RENTON CONTROL POINTS
NOS. 1866 AND 2110
VERTICAL DATUM
NAVD 88
BENCH MARK
ORIGINAL BENCHMARK:
CITY OF RENTON BENCH MARK NO. 2139
TOP OF 3" BRASS DISC SET IN DRILL HOLE OF LUMINARY STAMPED "KING COUNTY
.&)$
($672)ȭ 108TH AVE NE AT THE INTERSECTION WITH SE
3(7529,76.<5'$1'
:(672)%8,/',1*
ELEVATION = 400.99
(NOT SHOWN HEREON)
TBM "A"
TOP OF CHISELED SQUARE AT THE NORTHWEST CORNER OF THE WEST END OF
&21&5(7(6,'(:$/.217+(6287+6,'(2)6(7+67%(,1*
:(672)
7+(,17(56(&7,212)6(7+67$1'7+$9(6($1'
:(672)
CENTERLINE CROSSWALK TO FRED MEYER SHOPPING CENTER.
ELEVATION = 384.73
(NOT SHOWN HEREON)
TBM "B"
TOP OF RAIL ROAD SPIKE SET IN WEST FACE POWER POLE 1.2' ABOVE GRADE ON THE
EAST SIDE OF 105TH PL SE LOCATED AT THE APPROXIMATE EXTENSION OF THE
NORTH PROPERTY LINE.
ELEVATION = 380.33
(NOT SHOWN HEREON)
CIVIL SHEET INDEX
SHEET NO SHEET TITLE
C1.0 COVER SHEET
C1.1 DRAINAGE PLAN AND PROFILE
C1.2 DETAILS
CONSTRUCTION SEQUENCE
1.CONTRACTOR TO ARRANGE AND ATTEND PRE-CONSTRUCTION MEETING.
2.POST SIGN WITH NAME AND PHONE NUMBER OF CSWPP/ESC SUPERVISOR (MAY BE CONSOLIDATED
WITH THE REQUIRED NOTICE OF CONSTRUCTION SIGN.
3.FLAG OR FENCE CLEARING LIMITS.
4.INSTALL CATCH BASIN PROTECTION AND STORMWATER BMP AREA PROTECTION AS SHOWN ON
PLANS.
5.INSTALL SILT FENCE AS SHOWN ON PLANS.
6.MAINTAIN EROSION CONTROL MEASURES IN ACCORDANCE WITH APPENDIX D OF THE CITY OF
RENTON SURFACE WATER DESIGN MANUAL AND MANUFACTURE'S RECOMMENDATIONS.
7.RELOCATE EROSION CONTROL MEASURES OR INSTALL NEW MEASURES SO THAT AS SITE
CONDITIONS CHANGE THE EROSION AND SEDIMENT CONTROL AND POLLUTION PREVENTION IS
ALWAYS IN ACCORDANCE WITH THE CITY'S EROSION AND SEDIMENT CONTROL STANDARDS.
8.COVER ALL AREAS THAT WILL BE UNWORKED FOR MORE THAN SEVEN DAYS DURING THE DRY
SEASON OR TWO DAYS DURING THE WET SEASON WITH STRAW, WOOD FIBER MULCH, COMPOST,
OR EQUIVALENT.
9.STABILIZE ALL AREAS THAT REACH FINAL GRADE WITHIN SEVEN DAYS.
10.SEED OR SOD ANY AREAS TO REMAIN UNWORKED FOR MORE THAN 30 DAYS.
11.CONSTRUCT STORM LINE AS SHOWN ON PLAN. PROVIDE PAVEMENT PATCHING/RESTORATION AS
SHOWN ON PLANS.
12.UPON COMPLETION OF THE PROJECT, ALL DISTURBER AREAS MUST BE STABILIZED AND BMP'S
REMOVED.
IN COMPLIANCE WITH CITY OF RENTON STANDARDS 24Ä4Ä8#06#)').'05614/&4#+0':6'05+10%Ä.7# 1(8#06#)').'05614/&4#+0':6'05+105614/5;56'/':6'05+10
8#06#)').'0/1$+.'*1/'2#4-
-+0)%1706;*175+0)#76*14+6;6'&ÄÄWET SEASON SPECIAL PROVISIONS
1.THE ALLOWED TIME THAT A DISTURBED AREA MAY REMAIN UNWORKED WITHOUT COVER MEASURES
IS REDUCED TO TWO CONSECUTIVE WORKING DAYS, RATHER THAN SEVEN (SECTION D.2.1.2).
2.STOCKPILES AND STEEP CUT AND FILL SLOPES ARE TO BE PROTECTED IF UNWORKED FOR MORE
THAN 12 HOURS (SECTION D.2.1.2).
3.COVER MATERIALS SUFFICIENT TO COVER ALL DISTURBED AREAS SHALL BE STOCKPILED ON SITE
(SECTION D.2.1.2).
4.ALL AREAS THAT ARE TO BE UNWORKED DURING THE WET SEASON SHALL BE SEEDED WITHIN ONE
WEEK OF THE BEGINNING OF THE WET SEASON (SECTION D.2.1.2.6).
5.MULCH IS REQUIRED TO PROTECT ALL SEEDED AREAS (SECTION D.2.1.2.2).
6.FIFTY LINEAR FEET OF SILT FENCE (AND THE NECESSARY STAKES) PER ACRE OF DISTURBANCE
MUST BE STOCKPILED ON SITE (SECTION D.2.1.3.1).
7.CONSTRUCTION ROAD AND PARKING LOT STABILIZATION ARE REQUIRED FOR ALL SITES UNLESS THE
SITE IS UNDERLAIN BY COARSE-GRAINED SOIL (SECTION D.2.1.4.2).
8.SEDIMENT RETENTION IS REQUIRED UNLESS NO OFFSITE DISCHARGE IS ANTICIPATED FOR THE
SPECIFIED DESIGN FLOW (SECTION D.2.1.5).
9.SURFACE WATER CONTROLS ARE REQUIRED UNLESS NO OFFSITE DISCHARGE IS ANTICIPATED FOR
THE SPECIFIED DESIGN FLOW (SECTION D.2.1.6).
10.PHASING AND MORE CONSERVATIVE BMPS MUST BE EVALUATED FOR CONSTRUCTION ACTIVITY
NEAR SURFACE WATERS (SECTION D.2.4.3).
11.ANY RUNOFF GENERATED BY DEWATERING MAY BE REQUIRED TO DISCHARGE TO THE SANITARY
SEWER (WITH APPROPRIATE DISCHARGE AUTHORIZATION), PORTABLE SAND FILTER SYSTEMS, OR
HOLDING TANKS (SECTION D.2.2).P:\2017\17-030 KCHA Vantage Glen MHP\CAD\CIVIL\17-030_C1.0 and C1.1.dwg, 10/26/2017 11:58:47 AM, jhein10/26/2
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SD
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SDEXISTING SURFACE
Know what's
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A PORTION OF THE SW 1/4 OF THE NE 1/4 OF SECTION 32, TOWNSHIP 23, RANGE 5 E., W.M.
CITY OF RENTON, KING COUNTY, WASHINGTON
KING COUNTY HOUSING AUTHORITY-VANTAGE GLEN MOBILE HOME PARK
KEY NOTES:
1 REMOVE DEBRIS FROM EXISTING CATCH BASIN OR YARD DRAIN. SEE GENERAL NOTE 13.
2 PRIOR TO ANY CONSTRUCTION OR ORDERING OF MATERIALS CLEAN EXISTING STORM DRAIN PIPE. CONFIRM
CONDITION AND SERVICEABILITY OF EXISTING STORM DRAIN. CONFIRM POSITIVE PIPE SLOPE FROM EXISTING
CB #12027 TO NEW 10" STORM DRAIN. CONFIRM POSITIVE PIPE SLOPE FROM EXISTING CB# 11582 TO CB#11611
TO YD# 11728 OUT TO EXISTING 12" MAIN IN THE PRIVATE ROADWAY. REPLACE PIPE IF DAMAGED OR POSITIVE
SLOPE CANNOT BE ACHIEVED.
3 PROVIDE NEAT LINE SAWCUT AND PAVEMENT PATCH HOT TAR AND SEAL JOINT.
4 RECONSTRUCT IN-KIND CONCRETE ROLLED CURB AND GUTTER.
5 CONNECT NEW 10" STORM DRAIN TO EXISTING CATCH BASIN. SEE GENERAL NOTES.
6 PROTECT EXISTING UTILITIES AND STRUCTURES. RESTORE ANY DISTURBED AREA IN-KIND.
7 CONNECT EXISTING YARD DRAINS TO NEW 10" STORM LINE WITH WYE CONNECTION.
8 POTHOLE AND LOCATE EXISTING 8" STORM LINE. CONNECT DOWNSPOUTS TO EXISTING 8" STORM.
9 CONNECT EXISTING ROOF DRAIN DOWN SPOUT TO NEW 6" ROOF DRAIN AND PROVIDE CLEANOUT.
10 PROVIDE INLET PROTECTION. SEE DETAIL
11 CONFIRM 6" CMP CONNECTION FROM YARD DRAIN TO EXISTING 12" STORM DRAIN.
12 PROTECT EXISTING RETAINING WALL
1 2
3
1
2
1
1
1
5
46
46
GENERAL NOTES:
1.CONNECT ROOF DOWN SPOUTS AS SHOWN ON PLAN.
2.PROVIDE CB TYPE 1 PER CITY OF RENTON STD. PLAN 200.00.
3.PROVIDE 6" PVC ROOF DRAIN PIPING PER WSDOT STD SPEC 9-05.1(5). PIPE SLOPE
SHALL BE 0.5% MINIMUM.
4.PROVIDE 10" PVC SDR 35 PER WSDOT STD SPEC 9-05.12(1).
5.PROVIDE TOP SOIL AS REQURIED PER WSDOT STD SPEC 9-14.
6.PROVIDE ASPHALT PAVEMENT (HMA CL-1/2 PG 64-22) PER WSDOT STD SPEC 5-04.
7.PROVIDE CONCRETE ROLLED CURB IN-KIND CLASS 4000 PER WSDOT STD SPEC 5-05.
8.PROVIDE COMPACTION FOR ROCK BASE PER WSDOT STD SPEC 4-04.3(5).
9.PROVIDE VANED GRATE PER CITY OF RENTON STD. PLAN 204.20.
10.PROVIDE 6" STORM SEWER CLEAN OUT PER WSDOT STD PLAN B-85.40-00.
11.SEE SHEET C1.0 FOR EROSION CONTROL NOTES.
12.FIELD LOCATE DOWN SPOUTS (DS). CONNECT DOWN SPOUTS IDENTIFIED ON PLAN.
PROVIDE CLEAN OUT AT DOWN SPOUT CONNECTION.
13.CONTACT ENGINEER IF THERE ARE DISCREPANCIES IN CONNECTING ROOF DRAINS
AS SHOWN ON PLANS.
14.PROVIDE INLET PROTECTION PER DETAIL SHOWN ON SHEET 3 FOR THE NEXT
STRUCTURE DOWNSTREAM OF THE CONNECTION POINT.
15.ALL STORM DRAINAGE INFRASTRUCTURE SHOWN ON THIS PLAN WILL
BE PRIVATELY MAINTAINED BY VANTAGE GLEN MOBILE HOME PARK.
8
7
6
9 typ
10
10
IN COMPLIANCE WITH CITY OF RENTON STANDARDS 24Ä4Ä8#06#)').'05614/&4#+0':6'05+10%Ä.7# 1(8#06#)').'05614/&4#+0':6'05+105614/5;56'/':6'05+10
8#06#)').'0/1$+.'*1/'2#4-
-+0)%1706;*175+0)#76*14+6;6'&ÄÄ2
2
2
2
10
4
4
6
6
4
6
2 28
6
8
6
10
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P:\2017\17-030 KCHA Vantage Glen MHP\CAD\CIVIL\3rd Submittal 10.26.2017\17-030_C1.0 and C1.1.dwg, 10/27/2017 11:10:06 AM, jhein10/26/
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Know what's
R
A PORTION OF THE SW 1/4 OF THE NE 1/4 OF SECTION 32, TOWNSHIP 23, RANGE 5 E., W.M.
CITY OF RENTON, KING COUNTY, WASHINGTON
KING COUNTY HOUSING AUTHORITY-VANTAGE GLEN MOBILE HOME PARK
CATCH BASIN TYPE 11 CATCH BASIN INSTALLATION2 CATCH BASIN FILTER3 4 5PIPE COMPACTION DESIGN AND BACKFILL ASPHALT PATCH AND INTERFACE DETAIL
IN COMPLIANCE WITH CITY OF RENTON STANDARDS 24Ä4Ä8#06#)').'05614/&4#+0':6'05+10%Ä.7# 1(8#06#)').'05614/&4#+0':6'05+105614/5;56'/':6'05+10
8#06#)').'0/1$+.'*1/'2#4-
-+0)%1706;*175+0)#76*14+6;6'&ÄÄ*SDR 35 PIPE SHALL BE USED IN PLACE OF CMP AND LCPE AS SHOWN ON DETAIL ABOVE.
RECTANGULAR FRAME RECTANGULAR VANED GRATE7 RECTANGULAR SOLID METAL COVER8 9 SILT FENCE6
P:\2017\17-030 KCHA Vantage Glen MHP\CAD\CIVIL\17-030_C1.2 Details.dwg, 10/26/2017 11:59:38 AM, jhein10/26/201
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EXHIBIT 7
CONVEYANCE CALCULATIONS
STORM SEWER DESIGN (English Units)
This spreadsheet accomplishes a storm sewer design using the rational method. Enter the data in the non-shaded areas only.
Please use one spreadsheet per stormsewer run.
m =6.91 n =0.539 25 0.25 0.24
Location Discharge Drain Design Drain Profile
Drain Located On From Sta.To Sta.Source of
Drainage
Drainage
Area A
(acre)
Runoff
Coeff. C
CA (acre)Sum
CA
(acre)
Tc Across
Area
(minutes)
Total Tc = Col.
8a + Tc across
pipe length
(minutes)
Rainfall
Intensity
(in/hr)
Runoff (cfs)Contrib.
Inflow
(cfs)
Total Flow
(cfs)
Pipe Dia.
(in)
Manning
roughness
coefficient
"n"
Pipe
Slope
(ft/ft)
Velocity Of
Flow
(ft/s)
Pipe
Capacity
(cfs)
Pipe Velocity Check (Desirable
Minimum 3 ft/sec; Desirable
Maximum 10 ft/sec for Column 16)
Pipe Capacity Check (Column 13
vs. Column 17)
Pipe
Length***
(ft)
Elevation
Change (ft)
Upstr.
Invert Elev.
(ft)
Downstr.
Invert Elev.
(ft)
Upstr.
Ground
Elev. (ft)
Downstr.
Ground
Elev.
(ft)
1 2 3 4 5 6 7 8 8a 9 10 11 12 13 14 14a 15 16 17 17a 17b 18 19 20 21 22 23
Offsite North CB 12027 CB-1 Area 6 0.03 0.90 0.02 0.02 5.0 5.0 2.90 0.07 0.32 0.39 8 0.013 0.0100 3.46 1.21 VELOCITY OK ADEQUATE PIPE CAPACITY 70 0.70 337.90 337.20 343.48 340.04
See WSDOT Hydraulic Manual 6-5 for explanation of columns. http://www.wsdot.wa.gov/eesc/design/hydraulics/
Notes: Column 12 represents inflow from a storm sewer line, branch, an offsite source that flows into the trunk line being analyzed.
The conservative assumption is that the flow enters the storm sewer run at the upstream end of the run being analyzed.
For pipe cover calculation, Pipe cover = (Ground or Rim Elevation - Pipe invert elevation) - (pavement thickness) - (top of pipe thickness) - (pipe diameter).
The pipe thickness is based on the pipe diameter per WSDOT Manual Concrete for Shallow Pipe Cover Installations Fill Height Table 8-11.2
Please specify the largest pipe thickness of the storm sewer run being analyzed.
The spreadsheet will only calculate one storm sewer line at a time. Please copy the "Blank Template" and use this for calculating new storm sewer lines.
If analyzing complicated stormsewer system with multiple lateral lines to the trunk line, it is recommended that Stormshed be used to
model the conveyance system. Please contact your region Hydraulic Contact.
WARNING: START YOUR STORMSEWER RUN ON ROW 12. DO NOT SKIP ANY ROWS IN BETWEEN. USE ONE SHEET PER STORMSEWER RUN
Please report any problems to the WSDOT HQ Hydraulics Office.
Design Storm Event =
Project Name:Vantage Glen Stormline Extension Designed By:
Project Office:
Pipe Thickness (inches) =Pavement thickness (ft) =
11/21/2017 3:25 PM 1 of 2 2017-10-19_Storm_rational_25Yr_17030(revised).xls Offsite North
See Note 3
See Note 2 See Note 1
NOTES:
1. Velocity shown is based on pipe flowing full conditions. See Partially Full Pipe calculations for velocity based on anticipated flow condition noted in Column 13 above.
2. This spreadsheet is taken from the WSDOT Hydraulic Manual. Per WSDOT Hydraulic Manual, Tc minimum is 5 minutes for pipe capacity check using Rational Method.
3. "m" and "n" values per WSDOT Hydraulic Manual "index to Rainfall Coefficient," Figure 2-5.4A.
-1
STORM SEWER DESIGN (English Units)
This spreadsheet accomplishes a storm sewer design using the rational method. Enter the data in the non-shaded areas only.
Please use one spreadsheet per stormsewer run.
m =8.77 n =0.545 100 0.25 0.24
Location Discharge Drain Design Drain Profile
Drain Located On From Sta.To Sta.Source of
Drainage
Drainage
Area A
(acre)
Runoff
Coeff. C
CA (acre)Sum
CA
(acre)
Tc Across
Area
(minutes)
Total Tc = Col.
8a + Tc across
pipe length
(minutes)
Rainfall
Intensity
(in/hr)
Runoff (cfs)Contrib.
Inflow
(cfs)
Total Flow
(cfs)
Pipe Dia.
(in)
Manning
roughness
coefficient
"n"
Pipe
Slope
(ft/ft)
Velocity Of
Flow
(ft/s)
Pipe
Capacity
(cfs)
Pipe Velocity Check (Desirable
Minimum 3 ft/sec; Desirable
Maximum 10 ft/sec for Column 16)
Pipe Capacity Check (Column 13
vs. Column 17)
Pipe
Length***
(ft)
Elevation
Change (ft)
Upstr.
Invert Elev.
(ft)
Downstr.
Invert Elev.
(ft)
Upstr.
Ground
Elev. (ft)
Downstr.
Ground
Elev.
(ft)
1 2 3 4 5 6 7 8 8a 9 10 11 12 13 14 14a 15 16 17 17a 17b 18 19 20 21 22 23
Offsite North CB 12027 CB-1 Area 6 0.03 0.90 0.02 0.02 5.0 5.0 3.65 0.09 0.37 0.46 8 0.013 0.0100 3.46 1.21 VELOCITY OK ADEQUATE PIPE CAPACITY 70 0.70 337.90 337.20 343.48 340.04
See WSDOT Hydraulic Manual 6-5 for explanation of columns. http://www.wsdot.wa.gov/eesc/design/hydraulics/
Notes: Column 12 represents inflow from a storm sewer line, branch, an offsite source that flows into the trunk line being analyzed.
The conservative assumption is that the flow enters the storm sewer run at the upstream end of the run being analyzed.
For pipe cover calculation, Pipe cover = (Ground or Rim Elevation - Pipe invert elevation) - (pavement thickness) - (top of pipe thickness) - (pipe diameter).
The pipe thickness is based on the pipe diameter per WSDOT Manual Concrete for Shallow Pipe Cover Installations Fill Height Table 8-11.2
Please specify the largest pipe thickness of the storm sewer run being analyzed.
The spreadsheet will only calculate one storm sewer line at a time. Please copy the "Blank Template" and use this for calculating new storm sewer lines.
If analyzing complicated stormsewer system with multiple lateral lines to the trunk line, it is recommended that Stormshed be used to
model the conveyance system. Please contact your region Hydraulic Contact.
WARNING: START YOUR STORMSEWER RUN ON ROW 12. DO NOT SKIP ANY ROWS IN BETWEEN. USE ONE SHEET PER STORMSEWER RUN
Please report any problems to the WSDOT HQ Hydraulics Office.
Design Storm Event =
Project Name:Vantage Glen Stormline Extension Designed By:
Project Office:
Pipe Thickness (inches) =Pavement thickness (ft) =
11/21/2017 3:25 PM 1 of 2 2017-10-19_Storm_rational_100Yr_17030(revised).xls Offsite North
See Note 3
See Note 2 See Note 1
NOTES:
1. Velocity shown is based on pipe flowing full conditions. See Partially Full Pipe calculations for velocity based on anticipated flow condition noted in Column 13 above.
2. This spreadsheet is taken from the WSDOT Hydraulic Manual. Per WSDOT Hydraulic Manual, Tc minimum is 5 minutes for pipe capacity check using Rational Method.
3. "m" and "n" values per WSDOT Hydraulic Manual "index to Rainfall Coefficient," Figure 2-5.4A.