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HomeMy WebLinkAboutTIR-3910Grant Avenue Townhomes
Denton, Washington
Technical Information Report
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September 14, 2017 Pacific Engineering Job No. 15022
TECHNICAL INFORMATION REPORT
FOR
Grant Avenue Townhomes
RENTON, WASHINGTON
May 30, 2017
PREPARED FOR
Satwant Singh,
Skyline Properties, Inc.
50 116th Avenue SE, Suite 120
Bellevue, WA 98004
Phone: (425) 455-2065
E-mail: pmvrsingh@gmail.com
PREPARED BY
Pacific Engineering Design, LLC.
15445 53rd Avenue S
Seattle, WA 98188
Phone: (206) 431-7970
TABLE OF CONTENTS
Page
I. PROJECT OVERVIEW ............................................................................................... 3
Figure 1 Technical Information Worksheet to Follow ...................................................4
Figure 2 Site Location Map to Follow ...........................................................................
5
Figure 3 Drainage Basin, Subbasin and Site Characteristics .......................................6
Figure4 Soils ...............................................................................................................
7
11. CONDITIONS AND REQUIREMENTS SUMMARY ....................................................
8
Ill. OFF SITE ANALYSIS ...............................................................................................
15
Task 1 Study Area Definition and Maps .....................................................................
16
Task 2 Resource Review ...........................................................................................
17
Task 3 Field Inspection ..............................................................................................
18
Task 4 Drainage System Description and Potential Problems ...................................19
Task 5 Mitigation of Existing or Potential Problems ...................................................19
IV. FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN ...
20
Part A Existing Site Hydrology ...................................................................................
21
Part B Developed Site Hydrology ...............................................................................
22
Part C Performance Standards ..................................................................................
27
PartD Flow Control System .......................................................................................
28
Part E Water Quality System .....................................................................................
36
V. CONVEYANCE SYSTEM ANALYSIS AND DESIGN (REVISED 6/26/2012) ............
40
VI. SPECIAL REPORTS AND STUDIES .......................................................................
46
VII. OTHER PERMITS ...................................................................................................
47
VIII. CSWPPP ANALYSIS AND DESIGN ......................................................................
48
IX BOND QUANTITIES, FACILITY SUMMARIES AND DECLARATION OF
COVENANT...................................................................................................................
52
X. OPERATIONS AND MAINTENANCE MANUAL .......................................................
53
N
I. Proiect Overview
The proposed project will develop 8 townhome buildings (total 36 units) in parcel 202305-
9052. The site is located two parcels north of the northeast corner of the intersection of
South 18th Street and Grant Avenue South. The address of the site is 1600 Grant Avenue
South. The site area is 2.11 acres. The site is a trapezoidal property that is approximately
583' x 158' (average) with frontage on its western short side along Grant Avenue South.
The project site includes onsite development area and offsite improvement area along
the Grant Avenue South frontage. Total project site area is approximately 2.17 acres
including offsite improvement along Grant Avenue South. The site is located in the City
of Renton Residential Multi -Family (RM-F) zone. The site is surrounded by single-family
residents to the east and multi -family residences to the west and south and a Puget Sound
Power and Light Company property to the north. The site is located in the Thunder Hills
Creek drainage sub -basin of the Black River Drainage basin. The site is located in the
Duration with Forested conditions flow control area (Duration flow control with Forested
site conditions) and Enhanced Basic water quality control is required because the
proposed development is a multi -family development.
There is a single family house (built 1946) on the west portion of the site near the Grant
Avenue South. The house will be demolished and removed for the proposed
development. The remainder of the property is covered with grass with some scattered
trees. The site is hilly with average slope of 11 % slopes westerly toward Grant Avenue
South. There is no sensitive area on the site and no difficult conditions for the proposed
development.
For the onsite improvement, new plus replaced impervious area is approximately 1.35
acres, new pervious area is approximately 0.76 acres. Flow control BMPs, Native growth
protection area (2,595 sf.) and pervious concrete sidewalk (8,976 sf.) are used to treat
approximately 33.4% of the 36-lot areas. A combined detention/wet vault is used to
provide the required Duration standard forested site conditions flow control and a
treatment train of wet vault and StormFilter manhole with CSF cartridges is used to
provide the required Enhanced Basic water quality treatment.
The offsite frontage improvement creates approximately 1,760 square feet of new
impervious area (520 square feet of it is pollution generating impervious area) and no
new pervious area. For flow control, the new impervious area created by the offsite
improvement is counted as bypassed target area Per KCSWDM Section 1.2.3.2.E. The
onsite detention vault is oversized, so that the developed onsite detained runoff plus the
offsite bypassed runoff meets the required Duration standard forested site conditions flow
control requirements at the point of convergence (SDMH#1 at Grant Avenue South). For
water quality treatment, new pollution generating area is only 520 square feet and is
counted as untreated discharge per KCSWDM Section 1.2.8.2.D bypassing the water
quality treatment facilities.
3
Figure I Technical Information Worksheet to Follow
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Part 1 PROJECT OWNER AND
PROJECT ENGINEER
Project OwnerSkyline Properties, Inc.
Phone (425) 455-2065
Address 50 116 th Ave. SE . , # 12 0
Bellevue, WA 98004
Project Engineer Jings ong Feng, P.E.
Company Pacific Engr. Design, LLC.
Phone (206) 431-7970
Part 3 TYPE OF PERMIT APPLICATION
❑ Landuse Services
Subdivison / Short Subd. / UPD
® Building Services
M/ Commerical / SFR
® Clearing and Grading
® Right -of -Way Use
❑ Other
Part 2 PROJECT LOCATION AND
DESCRIPTION
Project Name Grant Avenue Townhomes
DDES Permit #
Location Township 23
Range 5
Section 20
Site Address 1600 Grant Ave. S .
Renton, WA 98055
Part 4 OTHER REVIEWS AND PERMITS.
❑
DFW HPA
❑ Shoreline
❑
COE 404
Management
❑
DOE Dam Safety
® StructumL
Rocke cult/
❑
FEMA Floodplain
®
ESA Section 7
❑
COE Wetlands
❑
Other
Park 5 PLAN AND REPORT" INFORMATION
Technical Information Report
Site Improvement Plan (Engr. Plans)
Type of Drainage Review Full Targeted /
Type (circle one): Full Modified /
(circle): arge Site
Small Site
Date (include revision
Date (include revision
dates):
dates):
Date of Final:
Date of Final:
Part 6 ADJUSTMENT APPROVALS
Type (circle one): Standard / Complex / Preapplication / Experimental / Blanket
Description: (include conditions in TIR Section 2)
Date of Approval:
2009 Surface Water Design Manual 1/9/2009
1
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Part 7 MONITORING REQUIREMENTS
Monitoring Required: (yes / No
Start Date:
Completion Date: _
Part 8 SITE COMMUNITY AND DRAINAGE BASIN
Describe:
Community Plan : Soos Creek
Special District Overlays:
DrainageBasin:Thunder Hills Creek sub -basin of Black River Drainage basin.
Stormwater Requirements: Duration with Forest Condition Flow Control
Part 9 ONSITE AND ADJACENT SENSITIVE AREAS
0 River/Stream Thunder Hills Creek ❑ Steep Slope
❑ Lake ® Erosion Hazard
❑ Wetlands 0 Landslide Hazard Moderate
❑ Closed Depression ❑ Coal Mine Hazard
❑ Floodplain ❑ Seismic Hazard
❑ Other ❑ Habitat Protection
Part 10 SOILS
Soil Type Slopes
AgC 8% to 15%
AgD 15% to 30%
❑ High Groundwater Table (within 5 feet) ❑ Sole Source Aquifer
® Other ❑ Seeps/Springs
❑ Additional Sheets Attached
Erosion Potential
Moderate
Severe
2009 Surface Water Design Manual 1/9/2009
2
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Part 11 DRAINAGE DESIGN LIMITATIONS
REFERENCE LIMITATION / SITE CONSTRAINT
❑ Core 2-OffsiteAnalysis Duration with forest condition
❑ Sensitive/Critical Areas
Flow control and Enhanced Basic
0 SEPA Water quality treatment.
❑ Other
Ll Additional Sheets Attached
Part 12 TIR SUMMARY SHEET
provide one TIR Summary Sheet per Threshold Discharge Area)
Threshold Discharge Area: Storm drainage system, at Grant Avenue South
name or description)
Core Requirements (all 8 apply)
Discharge at Natural Location
Number of Natural Discharge Locations: 1 at SDMH# 1
Offsite Analysis
Level: Q/ 2 / 3 dated:
Flow Control
Level: 1 < / 3 or Exemption Number
Incl. facility summary sheet
Small Site BMPs Perforated connections
Conveyance System
Spill containment located at: combined etention wet
vault & StormFilter manhole
Erosion and Sediment Control
ESC Site Supervisor:
Contact Phone:
After Hours Phone:
Maintenance and Operation
Responsibility: Private / ublic
If Private, Maintenance Log Required: Yes / No
Financial Guarantees and
Provided: Yes / No
Liability
Water Quality
Type: Basic / Sens. Lake C Enhanced Basicm Bog
(include facility summary sheet)
or Exemption No.
Landscape Management Plan: GDNo
Special Requirements as applicable
Area Specific Drainage
Type: CDA / SDO / MDP / BP / LMP / Shared Fac. / one
Requirements
Name:
Floodplain/Floodway Delineation
Type: Major / Minor / Exemption /None
100-year Base Flood Elevation (or range):
Datum:
Flood Protection Facilities
Describe: N/A
Source Control
Describe Ianduse: Multi -Family
(comm./industrial Ianduse)
Describe any structural controls:
2009 Surface Water Design Manual 3 1/9/2009
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Oil Control High -use Site: Yes
Treatment BMP:
Maintenance Agreement: Yes
with whom?
Other Drainage Structures
Describe:
Combined detention/wet vault
StormFilter manhole with CSF cartridges.
Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS
MINIMUM ESC REQUIREMENTS
MINIMUM ESC REQUIREMENTS
DURING CONSTRUCTION
AFTER CONSTRUCTION
Clearing Limits
Stabilize Exposed Surfaces
Cover Measures
Remove and Restore Temporary ESC Facilities
Perimeter Protection
0 Clean and Remove All Silt and Debris, Ensure
Traffic Area Stabilization
Operation of Permanent Facilities
Sediment Retention
Flag Limits of SAO and open space
preservation areas
Surface Water Collection
F1 Other
0 Dewatering Control
E) Dust Control
UJ Flow Control
Part 14 STORMWATER
FACILITY DESCRIPTIONS (Note: Include Facility Su mary and Sketch)
Flow Control
Type/Description
Water Quality
Type/Description
Detention
Comb. detention/
❑ Bio-filtration
wet vault
Comb. detention/
❑ Infiltration
0 Wetpool
wet vault
— StormFilter MH
Ll Regional Facility
Media Filtration
w/CSF cartridges
Perforated
J Shared Facility
L) Oil Control
Ul Flow Control
BMPs
connections
preserve ex. tree
Spill Control
Control BMPs
Pervious concrete❑Flow
LJ Other
S i d e Wa I k S
❑ Other
Grasscrete vault
access drivew4
2009 Surface Water Design Manual 4 1/9/2009
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
TECHNICAL INFORMATION REPORT (TIR) WORKSHEET
Part 15 EASEMENTS/TRACTS
Part 16 STRUCTURAL ANALYSIS
O Drainage Easement
a Cast in Place Vault
❑ Covenant
0 Retaining Wall
❑ Native Growth Protection Covenant
0 Rockery > 4' High
❑ Tract
❑ Structural on Steep Slope
❑ Other
® Other
Part 17 SIGNATURE OF PROFESSIONAL ENGINEER
I, or a civil engineer under my supervision, have visited the site. Actual site conditions as observed were
incorporated into this worksheet and the attached Technical Information Report. To the best of my
knowledge the information rovided here is accurate.
'11
2009 Surface Water Design Manual 1/9/2009
Figure 2 Site Location Map to Follow
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Soil Map —King County Area, Washington
Map Unit Legend
King County Area, Washington (WA633)
Map Unit Symbol Map Unit Name
Acres in AOI
Percent ofAO1
AgC Alderwood gravelly sandy loam,
8 to 15 percent slopes
1.2
53.9%
AgD Alderwood gravelly sandy loam,
15 to 30 percent slopes
1.1
46.1 //
Totals for Area of Interest
2.3
100.0% i
USDA Natural Resources Web Soil Survey 11/16/2015
Conservation Service National Cooperative Soil Survey Page 3 of 3
11. Conditions and Requirements Summary
CORE REQUIREMENTS - SECTION 1.2 OF KCSWDM
1.2.1 CORE REQUIREMENT #1: Discharge at the Natural Location
Under existing condition, the site sheet flows westerly to Grant Avenue South. The low
point of Grant Avenue South is located near the northwest corner of the site where there
are two type 1 catch basins at both sides of the street to collect street runoff. The street
drainage system drains to an existing storm manhole (SDMH#1) near the northwest
corner of the site. SDMH#1 has a 15" CMP outfall pipe that discharges westerly to
Thunder Hills Creek. Under developed condition, same drainage pattern will remain. The
outfall of the onsite storm system will be connected to SDMH#1, other than that, the offsite
storm system will remain unchanged.
1.2.2 CORE REQUIREMENT #2: Off -site Analysis
This core requirement has been addressed in Section III of this report.
1.2.3. CORE REQUIREMENT #3: Flow Control
Per SWDM section 1.2.3.3 and 5.2, Flow Control BMPs are required for the onsite
development. Since the site is a PUD with individual lots, the project is required to provide
BMP for minimum 10% of the individual lot areas. The feasibility and applicability of full
dispersion is studied first, the study found full dispersion is not suitable for this site to fully
disperse the new impervious areas and new non-native pervious areas because long
native flow path is not available due to the high impervious area ratio. Full infiltration is
also not suitable for this site because onsite soil is till soil (Alderwood gravelly sandy loam,
6 to 15% slopes, AgC and 15% to 25% slopes, AgD) according to City of Renton Soils
Map.
The following flow control BMPs are used:
1. Native growth retention area (TRACT C, 2,595 square feet, counted as pasture
area). Impervious area credit allowed by this BMP is 2,595/3.5 = 741 square feet.
2. Pervious concrete walkway for all onsite sidewalks (8,976 square feet, credited as
50% impervious area, 50% grass)
3. Grasscrete pavement for vault maintenance access driveway (1972 square feet,
credited as 50% impervious area, 50% grass)
4. Perforated tie lines for downspout connections. (no credit)
Total impervious area treated by flow control BMPs is 11,689 square feet which is
approximately 32.8% (> 10% of the total lot areas of the 36 zero lot line lots (total 35,630
square feet which is 3,563 square feet). Final signed Flow Control BMP Covenant is
required prior permit is issued and will be recorded with the PUD Plat map.
Onsite flow control facility is provided by a combined detention/wet vault to provide the
required Duration standard forested site conditions flow control.
1.2.4 CORE REQUIREMENT #4: Conveyance System
The new conveyance piping will be installed as needed. The new conveyance piping has
been checked to confirm compliance with chapter 4 of the 2009 KCSWDM.
Per City Amendments to the 2009 KCSWDM Section 1.2.4.1:
1. New pipe system shall be designed with sufficient capacity to convey and contain (at
the minimum) the 25-year peak flow with minimum 6 inches of free board, assuming
developed conditions for onsite tributary areas and existing conditions for any offsite
tributary areas.
2. Pipe system structures may overtop for runoff that exceed the 25-year design capacity,
provided the overflow from a 100-year runoff event does not create or aggravate a severe
flooding problem or severe erosion problem as described in Core Requirement #2. Any
overflow occurring onsite for runoff events up to and including the 100-year event must
discharge at the natural location for the project site. In residential subdivision, this
overflow must be contained within an onsite drainage easement, tract, covenant, or public
right-of-way.
3. The upstream end of a pipe system that receives runoff from an open drainage feature
(pond, ditch, etc.) shall be analyzed as a culvert.
The property south of the site (Heritage Village Condominiums) have their own drainage
system to intercept runoff before it reaches the site. For the two properties east of the
site (parcels 739900-0060 and 739900-0070), the roof and front yards of these properties
drain to the Jones drive SE drainage system and the back yards of them sheet flow to the
site (approximately 9,600 square feet). The property north of the site slopes westerly to
Grant Avenue South parallel with the site. The properties west of the site are located at
elevations lower than the site. An intercept storm will be installed near the east property
line of the site to collect the upstream offsite runoff from the east. The new conveyance
system is designed to convey and contain the 25-year peak flow with 6 inches of free
board and the 100-year peak flow and thus meets the requirements listed above. KCBW
is used for Back water analysis following the requirements of City Amendments to 2009
KCSWDM 4.2.1.2 and designed for the 100-year peak flow. The offsite upstream runoff
from the back yards of the two east adjacent properties is also drained to the onsite
combined detention vault, the orifices of the control structures inside the vault are
designed to bypass this offsite runoff. The wet vault and StormFilter manhole are
designed to also treated this additional offsite upstream runoff.
1.2.5 CORE REQUIREMENT #5: Erosion and Sediment Control
Erosion control will be installed as necessary for the frontage improvements and the on -
site improvement. See Section 8 of this report for temporary sediment trap sizing
calculations.
1.2.6 CORE REQUIREMENT #6: Maintenance and Operations
M
Any necessary maintenance of the onsite drainage system will be the responsibility of the
property owner and manager.
1.2.7 CORE REQUIREMENT #7: Bonds and Liability
Necessary bonds will be provided at the time the building permit plans are approved
and the construction started.
1.2.8 CORE REQUIREMENT #8: Water Quality
A treatment train of combined detention/wet vault and StormFilter manhole with CSF
cartridges is used to provide the required Enhanced Basic treatment for the project site
and upstream offsite runoff from the back yards of two east adjacent properties.
The project site includes onsite improvement and frontage improvement along Grant
Avenue. Due to the topographic of the site, the offsite improvement does not drain to
the onsite combined detention wet vault and StormFilter manhole system but water
quality treatment is not required for the sidewalk improvement along the Grant Avenue
frontage because sidewalk is not counted as pollution generating impervious area.
10
SPECIAL REQUIREMENTS - SECTION 1.3 OF KCSWDM
1.3.1 Special Requirement #1: Other Adopted Area Specific Requirements
No other area specific requirements are applicable. The site is not within a CDA, MDP,
BP, SCP, SWCP, LMP, FHRPU or SFDP.
1.3.2 Special Requirement #2: Flood Plain / Floodway Delineation
Not applicable to this site. There is no flood hazard area in the site. The site is not
within a floodplain or floodway. The site is not subject to inundation by the base flood or
channel migration.
1.3.3 Special Requirement #3: Flood Protection Facilities
Not applicable to this site. There is no flood hazard area in the site. The site does not
rely on any flood protection measures.
1.3.4 Special Requirement #4: Source Controls
The site is subject to water quality source control. Dumpsters and recycle bins will be
stored inside the garages of each units.
1.3.5 Special Requirement #5: Oil Control
The estimated ADT of the developed site is approximately 290. The threshold for high -
use site is ADT of 100 or more vehicles per 1,000 square feet of gross building area.
Gross building area of the site is approximately 39,806 square feet. The threshold for
high -use site is ADT of 3981 vehicles. Thus, ADT of the site will be less than the
threshold ADT. Oil control is not required. The flow control riser tees with orifices in the
flow control structures and the StormFilter manhole will provide enough treatment for oil
control, no extra treatment is required.
City of Renton Special Requirement #6: Aquifer Protection Area
Not applicable to this site. The site is not located in the Aquifer Protection Areas
(zone1, zone 1 modified and zone 2) shown on the City of Renton Aquifer Protection
Zones Map.
Ill. Off Site Analysis
15
Task 1 Study Area Definition and Maps
The site is located on the east side of Grant Avenue South, two parcels north of South
18th Street. The address of the site is 1600 Grant Avenue South. The parcel number of
the site is 202305-9052. The onsite area is 2.11 acres. The total project site area is
2.17 acres including the offsite improvement along Grant Avenue South. The site is
located in the Thunder Hills Creek drainage subbasin of the Black River Drainage
Basin. See attached Site Map and Topographical Map.
Task 2 Resource Review
The following resources have been reviewed for existing /potential problems in the
study area.
1) Adopted Basin Plans
Exhibit C, City of Renton Shoreline Master Program Update Restoration Plan, prepared
by City of Renton, dated March, 2010
http://www.ecy.wa.gov/programs/sea/shorelines/smp/mycomments/Renton/restoration
lap n.pdf
2) Finalized Drainage studies
None.
3) Basin Reconnaissance Summary Reports and 1"=400' scale problem summary
maps
City of Renton Shoreline Master Program, Final Shoreline Inventory and Analysis,
prepared by City of Renton, dated March, 2010
http://rentonwa.gov/uploadedFiles/Business/EDNSP/planning/2.3%20FINAL%20Invento
ry%20(3-31-10).pdf?n=2007
4) Critical Drainage Area maps
Do not apply in the City of Renton per City of Renton Surface Water Design Manual.
5) Sensitive Area Folio
See attached Sensitive Area Folio.
6) DNRP Drainage complaints and studies
None.
7) Road drainage problems
There are no road drainage problems within the study area.
8) U.S. Department of Agriculture, King County Soils Survey
The King County Soils Survey map and City of Renton Soils Map show Alderwood soil
on the site (AgD on the west portion of the site and AgC on the east portion of the site).
See attached Soils map.
9) Wetland Inventory
There is no wetland on the site and its adjacent areas.
10) Migrating river studies
There is no migrating river within the study area.
17
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XEN-r
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Renton Municipal Code Creeks For Reference On
Roads Rivers City Boundary I Inch = I Mile
-- I I
Wetlands Lakes Municipality Boundaries
IRenton Wetlands
Task 3 Field Inspection
There is a single family house (built 1946) on the west portion of the site near the Grant
Avenue South. The house will be demolished and removed for the proposed
development. The remainder of the property is covered with grass with some scattered
trees. The site is hilly with average slope of 11 % slopes westerly toward Grant Avenue
South. There is no sensitive area on the site.
Upstream:
The property south of the site (Heritage Village Condominiums) have their own drainage
system to intercept runoff before it reaches the site. The property north of the site
slopes westerly to Grant Avenue South parallel with the site.
The properties west of the site are located at elevations lower than the site. For the two
properties east of the site (parcels 739900-0060 and 739900-0070), the roof and front
yards of these properties drain to the Jones drive SE drainage system and the back
yards of them sheet flow to the site (approximately 9,600 square feet of till grass).
Total upstream drainage area flows to the site = 9,600 sf. = 0.22 acres (till grass).
Downstream:
Under existing condition, the site sheet flows westerly to Grant Avenue South. The low
point of Grant Avenue South is located near the northwest corner of the site where there
are two type 1 catch basins at both sides of the street to collect street runoff. The street
drainage system drains to a storm manhole (SDMH#1) near the northwest corner of the
site. SDMH#1 has a 15" CMP outfall pipe that discharges westerly to Thunder Hills
Creek. See attached City of Renton AS -built drawing R-123402. The 0.25-mile
downstream point is located at the Thunder Hills Creek. The 1 mile downstream point is
located at the city storm drainage system that drains to Springbrook Creek.
No capacity problem, erosion problem and water quality problem were found within 0.25
miles downstream of the site in the field inspection.
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Task 4 Drainage System Description and Potential Problems
There are no unsolved existing and potential drainage problems within 0.25 mile
downstream of the site.
Task 5 Mitigation of Existing or Potential Problems
There are no unsolved existing and potential drainage problems within 0.25 mile
downstream of the site.
For onsite improvement, for the onsite improvement, new plus replaced impervious area
is approximately 1.38 acres, new pervious area is approximately 0.73 acres. Flow
control BMPs, Native growth protection area (2,595 sf.) and pervious concrete sidewalk
(9,291 sf.) are used to treat approximately 33.4% of the 36-lot areas. A combined
detention/wet vault is used to provide the required Duration standard forested site
conditions flow control and a treatment train of wet vault and StormFilter manhole with
CSF cartridges is used to provide the required Enhanced Basic water quality treatment.
Treated runoff will be discharged to its natural discharged location (SDMH#1 at Grant
Avenue South). An intercept storm will be installed near the east property line of the
site to collect the upstream offsite runoff. The offsite upstream runoff from the back
yards of the two east adjacent properties is also drained to the onsite combined
detention vault, the orifices of the control structures inside the vault are designed to
bypass this offsite runoff. The wet vault and StormFilter manhole are designed to also
treated this additional offsite upstream runoff.
For offsite frontage improvement, as discussed in Section 1 of this report, the offsite
improvement will drain to the existing Grant Avenue storm system bypassing the onsite
flow control and water quality treatment facility, no additional flow control or water
quality treatment is required.
The proposed development will not create any adverse impact on the downstream
drainage system.
19
IV. Flow Control and Water Quality Facility Analysis
and Design
m
Part A Existing Site Hydrology
Duration standard forested site conditions flow control requires matching developed flow
duration from 50% of pre -developed 2-year peak to full 50-year peak and matching
peak discharge rates of developed 2 and 10-year peaks with the existing 2 and 10 year
peaks. Existing site condition is forest condition per City of Renton Flow Control
Application Map.
Onsite and offsite improvements
Scale factor = 1.00
Total onsite area = 2.11 acres (assume till forest)
Total offsite area (Grant Avenue South frontage) = 0.06 acres (assume till forest)
Total project site area = 2.17 acres (assume till forest).
Upstream offsite area = 0.22 acres (till grass, from back yards of the two east adjacent
properties)
Total drainage area = 2.39 acres
40. Land Use Summary
r-Area
Till Forest! 2.17 acres
Till Pasture=
0.00 acres
Till Grass'
0.22 acres
Outwash Forest;
0.00 acres
Outwash Pastured
0.00 acres
Outwash Grass:
0.00 acres
Wetland
0.00 acres
Imperviousl
0.00 acres
File for computed Time Series [.TSF]
X
41
Flow Frequency Analysis
Flow Frequency Analysis
Time Series File:pre.tsf
Project Location:Sea-Tac
---Annual
Peak
Flow Rates ---
Flow Rate
Rank
Time of
Peak
(CFS)
0.155
2
2/09/01
18:00
0.045
7
1/05/02
16:00
0.124
3
2/28/03
3:00
0.007
8
3/24/04
19:00
0.071
6
1/05/05
8:00
0.120
4
1/18/06
20:00
0.106
5
11/24/06
4:00
0.210
1
1/09/08
9:00
Computed Peaks
Existing peak flows
Q2y = 0.071 cfs
Q10y = 0.124 cfs
Q100y = 0.210 cfs
Flow Frequency Analysis-------
- - Peaks -
- Rank
Return
Prob
(CFS)
Period
0.210
1
100.00
0.990
0.155
2
25.00
0.960
0.124
3
10.00
0.900
0.120
4
5.00
0.800
0.106
5
3.00
0.667
0.071
6
2.00
0.500
0.045
7
1.30
0.231
0.007
8
1.10
0.091
0.192
50.00
0.980
22
0
rn
co
6
W
U)
W
2
O
z
O
(-
W
V
Q
J
n
H
z
Q
N
CD
(-
W
W
Cn
OFFSITE FRONTAGE AREA = 0.06 ACRES (TILL FOREST)
I � I
I
' 25'007' .
1 5.p' 0
�.�61,
UPSTREAM
TRIBUTARY
AREA
= 0 . 2 2 AC. C 0 10 20 30
TOTAL ONSITE AREA = 2.11 11 AC. (TILL FOREST)
ilri� Tr-
- (TILL
6.50 6383' GRAPHIC SCALE
GRASS) SCALE-1•-W
Found Brass
Mon. W/Punch
In Conc. in Case
7-16-05
R=200.62' r
L=55.53'
Found Brass ...�� --
Mon. W/Punch
In Conc. in Case
7-16-05
g
i = -
\ � _SDMH
` 1 I
'CB 30
M -4
V _
SURVEYOR
\ �_ ��� � 2'• - LEGAL DESCRIPTION tiURVE ORI
TREE TABLE I 11M GRIFFIN
AN UNDIVIDED ON -HALF INTEREST IN THE FOLLOWING DESCRIBED PROPERTY: TYEE SURVEYORS
III TYPE SIZE - DRIPLINE PORTION OF THE NORTHEAST QUARTER OF THE SOUTHWEST QUARTER DF 10007 GREENWOOD AVE. N
i ALDER iBk16
SOMH-2 "" 75 SECTION 20, TOWNSHIP 23 NORTH, ROUGE 5 EAST, W.M., IN KING COUNIM I SEATTLE, WA 98133
2 IE? dr14" 7V WASHINGfON, DESCRIBED AS FOLLOWS:
3 1B"WV' 50' PHONE: (206) 525-3660
4 �� �„ W. BEGINNING ON THE EAST LINE OF SAID SUBDTV SIDN AT A POINT WHICH IS
\ SOUTH 00'OB'49' WEST 475.79 FEET FROM THE NORTHEAST CORNER THEREOF;
5 CHERRY 16" dr14" 40' THENCE NDRTH woe;'49" EAST 158.00 FEET;
6 ALDER 12'•, B", B" 50' THENCE WEST PARALLEL WITH THE NORTH LINE OF SAID SUBDIVISION 654.50
7 1B" iB•• ID" 65, FEEP
Found Brass
Mon. W/"X"
B DECIDUOUS
9 MAPLE
1W. 3 X 6"
18", 12" 10", 1D", 14"
2D'
W.
THENCE SWIM 26'1B'S7" EAST TO THE INTERSECTION WITH A LINE EXTENDING
WESTERLY THROWN THE SAID POINT OF BEGINNING AND PARALLEL WITH THE
SYMBOLS LEGEND:
In Con[. in Case
7-16-05
ID MAPLE
11 LOCUST
ID"
2X74", 2X12", 6X1D", 3XB", B"
30'
10V
NORTH LINE OF SAID SUBDIVISION;
THENCE EAST ALDNG SAID EXTENDED LINE TO THE POINT OF BEGINNING:
EXCEPTION THEREFROM A STRPI OF LAND 30 FEET WIDE, PARALLEL WITH AND
I
❑
CATCH BASIN
`
13 FIT
II, 12"
aw
ADJDINING THE WESTERLY LINE OF SAID TRACT, FOR ROAD PURPOSES:
I
.p.
POWER POLE(AS NOTED)
EXISTING STORM STRUCTURES IN
GRANT AVENUE
,%` 1
14 "
12'
3V
SITUATE IN THE COUNTY OF KING, STATE OF WASHINGTON.
CB-1
SDMH-1 TYPE-2, SOLID LIO
1
-
1S "
16 " "
12"
12"
25'
30'
TAX PARCEL # 2D23059052
°0°0°°°
RDCKERY
RIM = 293.7
RIM = 294.5
I
17 MAPLE
12"
45'
STORM DRAIN MANHOLE
12' CMP S - 290.5
12" CMP N = 290.0 1
1B "
12"
TELEPHONE RISER
8" CPM W = 290.8
12" CMP NE = 289.9
19 "
if'
40•
MERIDIAN
GENERAL NOTES
15" CMP W = 286.6
'CB-5
20 ALDER
13"
35'
ES
WATER METER
RIM 2 293.9
12• CMP SW = 287.1
�,
I
„ ..
21 '• ,.
23 "
13"
14,.
14"
25'
40
40'
ASSUMED
DATUM
i. THE INFORMATION DEPICTED ON THIS MAP REPRESENTS THE RESULTS OF
A SURVEY MADE ON THE DATE INDICATED AND CAN ONLY BE CONSIDERED AS
INDICATING THE GENERAL CONDITION EXISTING AT THAT TIME
WATER VALVE
8" CMP E = 291.3
SDMH-2 TYPE-2, SOLID LIO
24" '•
14"
CONIFER(AS NOTED)
RIM = 313.9 I
25 ••
14"
3p•
30'
NAVD 86
BASED ON
IN THE
EYIOENCE�OF�UTNLIDTI6 (m6P WERE
]IENT�COVERS,
CB-3
36" CMP N = 304.4 /
I
26 "
14"
30'
CONTOUR INTERVAL = 2'
MMICS�SAW
LIDS ErcJ THE CONTRACTOR SWILL VERIFY THE EXACT LOCATION, ELEVATION
f�
�, j
DECIDUOUS(AS NOTED)
RIM = 307.5
12'• CMP SE = 308.5
27 •• ••
"
14"
30'
AND SIZE OF EXISTING UTILITIES PRIOR TO CDNSIRUCTION.
8" CMP = 305.3
CURVE
2e
14"
30'
EQUIPMENT & PROCEDURES
x
FENCE LINE AS NOTED
SDMH-3 TYPE-2, SOLID LID
=5149'25'
29
30 MAPLE
14"
14"
21Y55,
55'
3. TREE SIZES WERE LOCATED do SPECIES DETERMINED RA THE BEST OF
OUR ES TWEE SURVEYORS DOES NOT WARRANT THE ACCURACY
CB-4
RIM = 313.9 _
/
R=125.00'
31
14•
5G
A S' ELECTRONIC TOTAL STATION WAS USED FOR THIS FIELD
&Y. SPECIESSHOWN ANY EKED TO BE
SIZE CI
ICAL
RIM - 307.4
CMP S = 3304.
L=113. �•
T=60.73
32 ALDER
13"
30'
TRAVERSE SURVEY. ACCURACY MEETS OR EXCEEDS WAC.
332-130-090.
CRIB HOULD BE VERED BY AN. �T BORIST.
12 CMP W - 303.2
12" CMP E = 303.2
12"
12'� CMP SW = 304.4
/
33 CHERRY
34 u.OrR
IS,
16"
50,
40'
4. THIS MAP DOES NOT PURPORT TO SHOW EASEMENTS OF RECORD, IF ANY.
/
SDMH-4 TYPE-2, SOLID LIO
35 "
18'
35
BENCHMARKS
S. NO PROPERTY CORNERS WERE SET IN CONJUNCTIDN WITH THIS SURVEY.
Q //�
R-��,/ OO2
CB-5
RIM = 307.9
"
1B'
45'
ORIGINAL BM; FOUND BRASS DISK IN CONCRETE IN THE
RIM = 309.6
8" CMP SW = 303.45
37
38 "
1B"
2D"
45'
45'
INTERSECTION OF S 18TH ST AND GRAND AVE S. WGS
POINT DESIGNATION : RENT7B7.
8" CMP E = 307.5
12" CMP NE = 303.1
39.1
2W
50'
ELEV. _ 317.S7
APPROVED
FOR CONSTRUCTION
8" CMP W = 307.5
12" CMP NW = 302.9
40 " ';
41 ••
�;
V
1'
IBM - A: MSG NAIL IN SEAM 2' WEST OF TOP BACK CURB
SUBJECT TO
ERRORS AND OMISSIONS
42 FIR
V.
35•
35'
ON WEST SIDEWALK OF GRANT AVE S.
ON
43 ALDER
24"
45'
ELEV.308.B7
EXISTING SEWER STRUCTURES NEAR GRANT AVENUE
44 "
24•'
50'
TBM - B: SET HUB + MAG NAIL 2W +/- E OF SE CORNER OF
BY:
DATE: .
SSMH-2 TYPE-2, SOLID LID
45 " „
48 "
24•
24"
50,
40' -TREE IS DYING-
HOUSE
EL. a 31B.93
ELEV.
RIM = 315.6
47 FIR
24"
35'
BY:
DATE: .
8•' CONC IN N
48 " "
24"
35•
8" CONC IN E
BY:
DATE:
8" CONC OUT SW
50 ALDER
3v
5V
.
CTR CHANNEL = 303.4
51 ASH
S2 CEDAR
53 CHERRY
38
3s"
38"
7S'
50,
60'
BY:
DATE: .
„ TIac6fi r�r�J
gDesign, L L
Civil Engi;r" inn a
Pianniny ;;an:.vl't=iraaz;
T. GRIIFFIN 1"-20' 'I"am_ d1 CITY OF GRANT PLACE TOWNHOMES 2016-1
J. HOPPERRENTON
2 SECOND ROUND CITY REVIEW COMMENTS JF 4 JH E MARSHAL
1FIRST ROUND CITY REVIEW COMMENTS AL U242 = -J. HOPPER Planning/Building/Public Works Dept. EXISTING CONDITIONS
NO. REVISION BY DATE APPR f° "m0O Y
CO2
Ln
DO
DO
0
0
0
Ln
Q
J
I
Part B Developed Site Hydrology
Onsite improvement with upstream offsite runoff
Under developed condition, onsite runoffs and upstream offsite runoff from the east will
be collected and conveyed to the onsite detention system.
Onsite impervious area calculation:
Roofs of 8 new townhomes = 22,736 sf.
Public alley, driveway and parking = 24,567 sf.
Asphalt vault access driveway = 571 sf.
Grasscrete vault access driveway = 1,972 sf.
Pervious concrete sidewalk = 8,976 sf.
Total impervious area = 58,822 sf. = 1.35 acres. (roof, driveway, walkway, etc. before
apply flow control BMP credits)
The 8,976 sf. of pervious concrete sidewalk and 1,972 sf. of grasscrete vault access
driveway can be credited as 50% impervious area, 50% grass. After apply the credit,
they can be counted as 5,474 sf, of impervious area and 5,474 sf. of till grass.
The 2,595 square feet Tract C is set aside as Native Growth Protection Area, other than
the removal of dangers trees, this area will remain undisturbed. At least one existing
12" big leaf maple will remain, and 10 new trees will be planted in this area. This area
will be counted as till pasture under developed condition. Total 741 square feet of
impervious area (2,595/3.5 = 741) can be credited by this BMP.
After apply flow control credit
Total onsite impervious area = 58,822 — 5,474 — 741 = 52,607 sf. = 1.21 acres
Total onsite area = 2.11 acres
Total onsite pervious area = 2.11 — 1.21 = 0.90 acres
Native Growth Protection Area Tract C = 2,595 sf. = 0.06 acres (till pasture)
Onsite till grass = 0.90 — 0.06 = 0.84 acres
Upstream offsite drainage area from the east = 0.22 acres (till grass)
Total drainage area to the vault = 2.11 + 0.22 = 2.33 acres.
Total impervious area to the vault = 1.21 acres
Total till pasture to the vault = 0.06 acres
Total till grass to the vault = 1.06 acres
23
Land Use Summary
a_.Are .e.,_._
Till Forests 0.00 acres
Till Pasture 0.06 acres
Till Grass, 1.06 acres
File for computed Time Series [.TSF]
Flow Frequency Analysis
Time Series File:dev.tsf
Project Location:Sea-Tac
---Annual
Peak
Flow Rates ---
Flow Rate
Rank
Time of
Peak
(CFS)
0.391
5
2/09/01
2:00
0.308
8
1/05/02
16:00
0.472
2
2/27/03
7:00
0.321
7
8/26/04
2:00
0.390
6
10/28/04
16:00
0.414
4
1/18/06
16:00
0.467
3
10/26/06
0:00
0.803
1
1/09/08
6:00
Computed Peaks
-----Flow
Frequency
Analysis -------
- - Peaks
- - Rank Return
Prob
(CFS)
Period
0.803
1
100.00
0.990
0.472
2
25.00
0.960
0.467
3
10.00
0.900
0.414
4
5.00
0.800
0.391
5
3.00
0.667
0.390
6
2.00
0.500
0.321
7
1.30
0.231
0.308
8
1.10
0.091
0.693
50.00
0.980
Developed condition peak flows before detention:
Q2y = 0.390cfs
Q 10y = 0.467 cfs
Q100y = 0.803 cfs
24
Offsite improvement Counted as bypass areas
Under developed condition the right of way frontage improvement will create 1,200
square feet (0.03 acres) new plus replaced impervious area.
Total offsite bypass area = 0.06 ac.
Impervious area = 0.030 ac.
Pervious area = 0.030 ac. (till grass)
Land Use Surma yr
,--Area
Till Forest!
0.00 acres
Till Pasture,
0.00 acres
Till Grass}
0.03 acres
Outwash Forest,
0.00 acres
Outwash Pasture�
0.00 acres
Outwash Grass!
0.00 acres
Wetland!
0.00 acres
Impervious,
0.03 acres
Flow Frequency Analysis
Time Series
File:offsite.tsf
Project
Location:Sea-Tac
---Annual
Peak
Flow Rates ---
Flow Rate
Rank
Time of Peak
(CFS)
0.010
5
2/09/01 2:00
0.008
7
1/05/02 16:00
0.012
2
2/27/03 7:00
0.008
8
8/26/04 2:00
0.010
6
10/28/04 16:00
0.011
4
1/18/06 16:00
0.012
3
10/26/06 0:00
-----Flow
Frequency Analysis -------
- - Peaks
- - Rank
Return
Prob
(CFS)
Period
0.020
1
100.00
0.990
0.012
2
25.00
0.960
0.012
3
10.00
0.900
0.011
4
5.00
0.800
0.010
5
3.00
0.667
0.010
6
2.00
0.500
0.008
7
1.30
0.231
25
0.020 1 1/09/08 6:00 0.008 8 1.10 0.091
Computed Peaks 0.018 50.00 0.980
Developed condition offsite bypass peak flows:
Q2Y = 0.010 cfs
Q1 Oy = 0.012 cfs
Q1 OOY = 0.020 cfs
The hydrograph of the onsite detained runoff (detention vault release, include the 0.22
acre upstream tributary area, rdout.tsf) will be added with the hydrograph of the offsite
bypass area (Grant Avenue South frontage improvement, offsite.tsf). The combined
hydrograph (dsout.tsf) is used to compare with the existing hydrograph of the total
combined site (including onsite area 2.11 acres, upstream tributary area 0.22 acres and
Grant Avenue South frontage improvement area 0.06 acres, total 2.39 acres, pre.tsf) at
the point of compliance at existing storm manhole SDMH#1 at Grant Avenue South to
meet the requirements of Level 2 detention.
M
0
m
C'')
O
W
F-
U
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J
z
CC
CD
F-
W
W
U)
---------------------- -------------------
\ /TI E, Unu A
\ oa A
PA
� 15'S1'32'
R=200.62' +.
LOT AREA TABLE
1
1,076 SF
2
846 SF
3
1,025 SF
4
846 SF
5
1,076 SF
6
1,076 SF
7
846 SF
8
1,025 SF
9
1,076 SF
10
1,076 SF
11
846 SF
12
1,025 SF
13
1,076 SF
14
1,083 SF
15
851 SF
16
1,032 SF
17
851 SF
18
1,083 SF
19
1,083 SF
20
851 SF
21
1,032 SF
22
851 SF
23
1,083 SF
24
1,076 SF
25
846 SF
26
1,025 SF
27
1,076 SF
28
1,076 SF
29
846 SF
30
1,025 SF
31
1,076 SF
32
1,076 SF
33
846 SF
34
1,025 SF
35
846 SF
36
1,076 SF
TOTAL
35,630 SF
MIN.
846 SF
MAX.
1,083 SF
AVC.
990 SF
1 12 I 3 I II 4 I 5'
1,076SF1846SFI1 025SF ,W_SF11 0765
�.,...__...,... e _,.
I
I
T,
-
_�a-
I I I I
36 1 35 1 34 1 33 1 32
1,076SF 1846SFI1,025SFi 846SFI1,0765
:0
Y1711T, 0;
6 ' 7 8 9
11 076SF ' 846SFI1,025SF I 1 076SF
I
SD SC
pa ._.--_ 1 a . 1__ a I ..
1 1 1 I
I 31 1 30 1 29 1 28
1.076SF;1,025SFTB46SF,1,076SF
- 544.56' -
s 89ro9'24' w
10 11 12 13
11,076SF1846SFf1,025SF11,076SF1
1 1 1
27 1 26 1 25 p 24
1,076SF;1,025SF; 846SF 11,076SF
14 1 15 1 16 1 17 1 18
1.073SFi843SF11,022SF1843SFj1,073SF
SITE
Ln
00
1 SCALE: 1'=1000' CD
1 1 20 11I 1 - SHEEP INDEX.- 00
8435d 1 022SF 843SF' 1,073SF 1 C01 -COVER Ln
1 073SF CO2 - EXISTINC CONDITIONS
I CO3 - SITE PLAN AND HORIZONTAL CONTROL PLAN ¢
C04 - CONDITIONS OF APPROVAL
� TRACT B - -
(INGRESS, EGRESS,
UTILITY, AND OPEN
I I SPACE) 12,453SF
I
I
I
I
i1w
I N
I $;
•- ,
/
w
- ..�
g S&- I i�
1
-
TRACT C (TREE PRESERVATION)
2,595SF
C06 - TEMPORARY EROSION AND SEDIMENT CONTROL PLAN
C07 - TEMPORARY EROSION AND SEDIMENT CONTROL NOTES AND DETAILS
C08 - CRAOINC ROADWAY AND DRAINAGE PLAN
C09 - ROAD AND STORM PROFILES
C10 - VAULT PLAN
_I
C11 - VAULT SECTIONS
- - - _ _
C12 - STORMFILTER MANHOLE DETAILS
e
C17 - COMPOSITE UTILITY PLAN
LEGEAD:
\ SD STORM MAIN LINE
- - - - - - - - - - - STORM TICHT LINE
-" ® TYPE 1 CATCHBASIN
Q TYPE 2 CATCHBASIN 9TE INFORMATION-
® STORM CLEANOUT
SS SEWER MAIN LINE ADDRESS: 1600 CRANT AVE S
SIDE SEWER LINE PARCEL NUMBER: 202305-9052
IN 1 0 ZONINC: RM-F
SEWER MANHOLE PARCEL AREA: 92,051 SF (2.11AC)
1 SEWER CLEANOUT OISTURBED AREA: B9,451 SF (2.05 AC)
WATER MAIN LINE EXISTINC IMPERVIOUS AREA: 3,900 SF (0.09 AC)
W
I GROSS NEW IMPERVIOUS AREA: 58,866 SF (1.35 AC)
WATER SERVICE LINE NET NEW IMPERVIOUS AREA: 54,966 SF (1.26 AC)
0 WATER METER
�+ WATER TEE
I I H WATER VALVE BUILDING AREAS:
BUILDING 1 3,2B4 SF
*__0 FIRE HYDRANT ASSEMBLY BUILDING 2 Z723 SF
WATER BENDS BUILDINC 3 Z723 SF
BUILDINC 4 31284 SF
/[ WATER CAB W/ 8.0. BULDNC 5 3,284 SF
CL CURVE UTILITY LINES BUILDINC 6 Z723 SF
0=51'49'25' BUILDING 7 2,723 SF
/ R=125.00' 312 2-FOOT CONTOUR LINE BUILDING 8 3,284 SF
Ala / L=113.0§' _ _ TOTAL 24,028 SF
T=60.73 310 10-FOOT CONTOUR LINE
/ oGmGCOGOCm]Om ROCKERY BUILDINC COVERACE: 26%
PROPERTY LINE UTILITY PURVEYORS:
- - LOT LINE
R.O.W. LINE WATER CITY OF RENTON
- - - - - EASEMENT LINE SEWER CITY OF RENTON
STORMWATER CIYT OF RENTON
CURB LINE
BUILDINC LINE
CLIENT/ DEVELOPER: CML ENG JNEER: SURVEYOR:
H JOE HOPPER nM CRIFFTN
TRACT �9,206 �SABLE
F 0.44 AC
TRACT 8 12,453 SF 0.29 AC
TRACT C 2,595 SF 0.06 AC
TOTAL 34,254 SF 0.79 AC
SATWNT SING
A
SKYLINE PROPERTIES, INC. PACIFIC ENGINEERING DESIGN, LLC TYEE SURVEYORS
50 116TH AVE SE, SUITE 120 15445 53RO AVE S., SUITE 100 10007 GREENWOOD AVE. N
8ELIEWE, WA 98004 SEATTLE, WA 98188 SEATTLE, WA 98133
PHONE: (206) 431-7970 PHONE: (206) 525-3660
F.PN M.HQ,00
p5 of SHi F
C18 -WASTEWATER AND WATER UTILITY PLAN
C19 - WASTEWATER AND WATER UTILITY PROFILES
C13 - DETAILS
C14 - DETAILS
C20 - OETATLS
C21 - DETAILS
30 0 10 zo so so C16 - TREE RETENTION PLAN
L100-L101 LANDSCAPE PLANS
L200-L202 IRRIGATION PLANS
GRAPHIC SCALE
SATWNT SING
A
SKYLINE PROPERTIES, INC. PACIFIC ENGINEERING DESIGN, LLC TYEE SURVEYORS
50 116TH AVE SE, SUITE 120 15445 53RO AVE S., SUITE 100 10007 GREENWOOD AVE. N
8ELIEWE, WA 98004 SEATTLE, WA 98188 SEATTLE, WA 98133
PHONE: (206) 431-7970 PHONE: (206) 525-3660
F.PN M.HQ,00
p5 of SHi F
C18 -WASTEWATER AND WATER UTILITY PLAN
C19 - WASTEWATER AND WATER UTILITY PROFILES
C13 - DETAILS
C14 - DETAILS
C20 - OETATLS
C21 - DETAILS
30 0 10 zo so so C16 - TREE RETENTION PLAN
L100-L101 LANDSCAPE PLANS
L200-L202 IRRIGATION PLANS
GRAPHIC SCALE
C18 -WASTEWATER AND WATER UTILITY PLAN
C19 - WASTEWATER AND WATER UTILITY PROFILES
C13 - DETAILS
C14 - DETAILS
C20 - OETATLS
C21 - DETAILS
30 0 10 zo so so C16 - TREE RETENTION PLAN
L100-L101 LANDSCAPE PLANS
L200-L202 IRRIGATION PLANS
GRAPHIC SCALE
SCALE:1'-30'
LEGAL DESCWPON--
GENERAL SURVEY NOTESr
AN UNDIVIDED ON -HALF INTEREST IN THE FOLLOWINC OESCR18ED PROPERTY:
1. THE INFORMATION DEPICTED ON THIS MAP REPRESENTS THE RESULTS OF A
PORTION OF THE NORTHEAST QUARTER OF THE SOUTHWEST QUARTER OF SECTION
SURVEY MADE ON THE DATE INDICATED AND CAN ONLY BE CONSIDERED AS
20, TOWNSHIP 23 NORTH, RANCE 5 EAST, W.M., IN KINC COUNTY, WASHINGTON,
INOICATINC THE GENERAL CONDITION EXISTINC AT THAT TIME.
DESCRIBED AS FOLLOWS:
8ECINNINC ON THE EAST LINE OF SAID SUBOMSION AT A POINT WHICH IS SOUTH
2. UNDERCROUNO UTILITIES WERE LOCATED BASED ON THE SURFACE EVIDENCE
00'08'49" WEST 475.79 FEET FROM THE NORTHEAST CORNER THEREOF;
OF UTILITIES (I.E. PAINT MARKS, SAW CUTS IN PAVEMENT, COVERS, LIDS ETC.)
THENCE NORTH 00'08'49" EAST 158.00 FEET;
THE CONTRACTOR SHALL VERIFY THE EXACT LOCATION, ELEVATION AND SIZE OF
THENCE WEST PARALLEL WITH THE NORTH LINE OF SAID SU8OMSION 654.50 FEET;
EXISTING UTILITIES PRIOR TO CONSTRUCTION.
THENCE SOUTH 26'18'57" EAST TO THE INTERSECTION WITH A LINE EXTENDING
WESTERLY THROUGH THE SAID POINT OF 8ECINNINC AND PARALLEL WITH THE
3. TREE SIZES WERE LOCATED &SPECIES DETERMINED TO THE BEST OF OUR
NORTH LINE OF SAID SUBDIVISION;
ABILITY. HOWEVER, TYEE SURVEYORS DOES NOT WARRANT THE ACCURACY OF SIZE
THENCE EAST ALONG SAID EXTENDED LINE TO THE POINT BEGINNING;
& SPECIES SHOWN HEREON. ANY TREES CONSIDERED TO BE CRITICAL SHOULD
PA
EXCEPTION THEREFROM A STRIP OF LAND 30 FEET WIDE, PARALLEL WITH AND
8E VERIFIED BY A TRAINED AR80RIST.
ADJOININC THE WESTERLY LINE OF SAID TRACT, FOR ROAD PURPOSES;
SITUATE IN THE COUNTY OF KINC, STATE OF WASHINGTON.
4. THIS MAP GOES NOT PURPORT' TO SHOW EASEMENTS OF RECORD, IF ANY.
TAX PARCEL # 2023059052
5. NO PROPERTY CORNERS WERE SET IN CONJUNCTION WITH THIS SURVEY.
MEPoDIAN-
ASSUMED
ALL EXISTING AND PROPOSED IMPROVEMENTS SHALL BE LOCATED AND
DATUM
DIMENSIONED TO CITY OF RENTON SURVEY MONUMENTS, MONUMENT LINES OR
STREET CENTERUNES. DIMENSIONS MUST BE DONE BY STATIONINC AND OFFSET
NAVD 88
FROM THESE CONTROL LINES.
BENCHMARKS
NPDES PERMINi: WAR # (PENDING 30 DAY COMMENT PERI00)
ORICINAL 8M: FOUND BRASS DISK IN CONCRETE IN THE INTERSECTION OF S
18TH ST AND GRANO AVE S. WCS POINT OESIGNATION : RENT787.
NORTHINC = 172,295.95
EASTING = 1,302,573.67
ELEV. = 317.57
R-391001
LWEST OF TOP BACK CURB ON WEST
TBM - A SETMACO
IOEWAG RANT AVE S
APPROVED FOR CONSTRUCTION
ELEV. = 309.81
SUBJECT TO ERRORS AND OMISSIONS
TBM - 8: SET HUB + MAC NAIL 20' +/- E OF SE CORNER OF HOUSE.
ELEV. = 31 B.93
BY: DATE:
C.O.R. 8M: MONUMENT IN CASE IN THE INTERSECTION OF EACLE RIDGE DRIVE
SOUTH AND SOUTH 18TH STREET. RENTON MONUMENT IO #1063
BY; DATE:
NORTHINC = 172,968.69
EASTINC = 1,301,533.10
BY. DATE:
ELEV. = 261.21
BY: DATE:
1E1/4� SWI/4� SEC. 20, T. 23 14, R 5 E, WM
Pacificj u=:.r1rj� ti T. «:�, � 1._,�. �� :�. a� ,� CITY OF
J{ �' Design,
, - 1, ✓ ONA LTE E2 SECOND ROUND CITY REVIEW COMMENTS JF 4 JH "" E. ( RENTON
J'I j1,,1� r 1 FIRST ROUND CITY REVIEW COMMENTS AL 2 1 JH a®m al =�� DATUM Plannin 80din Public Works Dept.
1-� Civil Engineering .'.-/17 . 4 /17 J. !TOPPER 9/ 9/ P
1 ' - Planning Casnsu7:vr,"z N0. REVISION BYDATE APPR• r
.orc iemio�ar
GRANT PLACE TOWNHOMES
COVER
U)
W
0
Z
0
F-
W
U
J
F-
z
¢
cc
0
CS #14 ALL ONSITE WALKWAYS To BE POROUS "` ;- EAFiI'FIW S CALCS
p (HIGH FLOW BYPASS) PAVEMENT, TOTAL 9,D31 SF. 'SEE SHEET CUTE 2, 00 CU YD
r NOTES o ca-11 14LF 12' LCPE / C14 FOR DETAIL (TYP.) PUBLIC WATER EASEMENT FILL- 21200 CU YD
p� FOR NEW STDRM DRAIN RIMS AND INVERTS -- STORMFILTER MANHOLE / (FROM R.O.W. LINE TO PU CB #13 NEf: 1D0 CU,-YD [CUT]
07 SEE PRDFILE AND STRUCTURE TABLE DN i _ SFMH#1W/CSF CARTRIDGES' CS 1D4LF 12" LCPE 1DEILF 12" LCPE BVlm340 s -
c6 #5 87LF 72` LCPE 44LF 12" LCPE-
SHEET CD9 CB#8 -- a ____ ___ _ - --
O 82LF�12' LCPE _ -- -- - - --
• FDR EXISTING STORM DRAINAGE SYSTEM SDLF 2�' LCPE _
ALDNG GRANT AVENUE AND DTHER OFFSITE BW=304312- 8W 3t BW-320 'CB#12 s
354
- - - _ ,
-a
W STDRM DRAINAGE SYSTEM SEE SHEET CD2 ` � n ;- _ \ rL,
-
• FOR STANDARD STORM DRAIN MATERIALS s
I AND DETAILS SEE CITY DF RENTON " - -
w..:
STANDARD DETAIL PLANS. \ - -:: : :: ::: :
..v' ... ..:: x
4 HEIGHT
.. :... :. ..... u II
ALL WALLS EXCEEDINGFEET IN HEI 11 T FF 115 n
WILL REQUIRE SEPARATE BUILDING PERMITS. = W 359
• DETENTION VAULTS WILL REQUIRE SEPARATE INGRESS/EGRESS AND LITY '. 2 12.`: LCPE 1ST Fes- 1'sr FF 11ST FF= S T FF-
(n EASEMENT TO BE OBTAINS ,r " " •• 348 d I D FF I 351E 1 0 ( 354.5
W BUILDING PERMIT. FROM PSE _ I` 1ST FF= r. ND FF- 2ND FF 2ND FF= 2ND FF- 2ND FF- L
• ALL STORM DRAINS IN ALLEY TO BE PUBLIC. , 1ST FF= 1ST FF= 1ST FF= 1ST FF= 1ST FF= 1ST FF= 1ST FF- 1ST FF= IST FF= IST FF= 1ST FF- 1ST FF= 335.D * 358.5' 36D.0 361.5 363.0 364.5 I BW�
34LF 12 LGPE "' 376.0 . 1317.5 I 317.5 1317.5 I 3'9.D 324.D i 325.5 I 325.5 I 327.D 332D 1 333.5 333.5 2ND FF= r.
5LF 12' CPE
SEE SHEET CD3 FOR CITY EASEMENT DN BW 309
'. I I I 345.D I CB #18
O TRACT A FOR VAULT MAINTENANCE, SIGNS 1DWIDE TYPE Cl \ % ' sw C� #15 I I I I I I I 9 ew-35e
AND ONE WAY ARRDWS ON PAVEMENT DRIVEWAY PER RENTON U- T
z ALDNG PUBLIC ALLEY. STD PLAN 1D4 \ _ 'N �� a �`
f Lr
ew=352
0 B #7 C
0 ROW CONTROL BMPS USED: \ � ;: _
EXISTING
ONSITE PERVIOUS CONCRETE SIDEWALK=9,D31 SF. xp s T I 1ST FF= 11 ST FF=I 1ST FF I. BW-352
W 15FF-
348 5 350.D 351.5 353 U 354.E I ,.i
GRASSCRETE VAULT ACCESS DRIVEWAY=1,973 SF. - 2ND FF-'I2ND FF � 2ND FF- 12ND FF� 2ND FF= I
() 121 12' LC E (PRVATE) 1D3LF 1g� LCPEI(PRNAjE) I 1 1ST FF- 358.5- 36D.D
TREE PRESERVATION (TRACT C) = 2,595 SF. VAULT ED PUBLIC D NTION/WE7 I 1 1'
Q VAULT .�1. \ 31 LF 12' PE (PRIVAT(� 1ST FF- 1ST FF 1ST FF- 1ST FF= 1ST: FF= S3 . - 115T:FF=1 D FF : I I 3d 5 1363.0 I 36 .5 ..
J 0• X 1STFF= I7 ST FF-I 15T'FF= 115T FF=1 isT FF- - ( - I -)
� CONSERVATION FLOW CONTROL 8' DEEP LIVE GE j1 FF 316.D 376.D 316.D 317.5 322.0 323.5 1323.5 325.0 33D.5 332.D 332.D 2ND FF=
343.5 '
2B,8DOCF TOT PROVIDED 6� Ln
FACILITY F- 28,767CF R IZED A l z�fl „- gWa3pg. , - C WOOD
00
z 4' DEEP D STORAGE \ 1�/ _ : _ FEN.E::AL p
Q PUBLIC CDMBINED DETENTION/WET VAULT. l3,6DDCF OTAL PROVIDED _ .:
_ N'
7,26DC EQUIRED ,'\ .. W.. ..r m TRACT C LINE :SEEPS O
_ r tax-34t �" - -- - - --JOE7AIL C13
U ENHANCED BASIC WO FACILITY Ex. EEr ucHr To \ \ - = s ss ss s -sr - s -Lb
-
- -- I 1
too;- AJ .
TREATMENT TRAIN OF PUBLIC COMBINED - 66 YD-
DETENTION/WET VAULT AND STORMFILTER D' WIDE TYPE C18 \ "� CB #2 --.. .--__-- BW-338 8N-338
MANHOLE W/CST CARTRIDGES. DRVEWAY PER RENTON \�� TD+t 10 WIDE TYPE C1 CB #3 ___- CB 7D8LF 12' LCPE. 23LF 6' LCRE : --I
S1D PLAN 704.4, 99LF 12' LCPE I
,:' DRIVEWAY PER RENTON 1 IALONG SOOUfH. PROPERTY
9DLF 12' LCPE
SIDEWALK AT DRIVEWAY �..�_. , m STD PLAN 7D4 R.O.W. LINE
CROSSING SHOULD NOT '' LINE, SEE SHEET C13
00 OFFSITE FRONTAGE LOCATIONS DEPRESSED AT / v `a 4. ' v ' TOTAL ONSITE AREA 1 =2 . 11 AC.A UPSTREAM FOR LTRIBU
60LF 12" LCPE
O LOCATIONS WHERE ce 3SD \ q CB #112' LCPE
I- AREA = 0 . 0 6 AC . LANDSCAPING IS MDRE Ex�snr/c cuRe ° TRIBUTARY
THAN s FEET WIDE TOTALIMPERVIOUS AREA �l�_21 C .�, 3D ° '° 2D 3D 6D
w IMPEVIOUS AREA = 0.03 AC.
z v ' v' (AFTER APPLY FLOW CONTROL BMP CREDITS) AREA=0.22 AC.GFIA�HICSCALE
TILL GRASS = 0. 03 AC. SC E:1'-W'
6D' PUBLIC R.O.W. \ -
\s r- TILL GRASS = 1.06 AC., TILL PASTURE = 0.06 AC. (TILL GRASS)
R.O.W. 31.5' PUBLIC 1/2 R.O.W. 2D.5' PUBLIC R.O.W. 2.5' 21' PUBLIC R.O.W. 2.5' 2D.5' PUBLIC R.O.W. 2D.5' PUBLIC R.O.W. 3'
3D' 35' SIDEWALK D' 3 3 3 3
') o I o --__ 2D' TRAVELLED WAY �� o I o B -
1.5' R.D.W. DEDICATIDN i� 5' PRIVATE SIDEWALK 5' PRIVATE SIDEWALK I LAND-
35.87't TRAVELLED WAY (VARIES) B' I � 2D' TRAVELLED WAY I 2D' TRAVELLED WAY 1 �
EXISSIDE AL LANDSCAPE F N F N
' SIDEWALK EXISTING 16.D 4" THICK CONCRETE 4" THICK CDNCRETE I =4" THICK CONCRETE SOAPING' 2D TRAVELLED WAY
CURB (TYPICAL) 6" 41DEWALK o o I o
EXISTING 1D I. 1D [ SIDEWALK = 1D' 1D' = 1D' 1D' 1D' 1D'
PAVEMENT 2% 1.5 i �'li 3 3 ' �SIDEWALK w =
CENTER LINE OF 1 I 0 I it o ( zl
�I PAVE NT D.6't CURB S) I3 B% CURB ex e% 6� B% CURB B% INSTALL WOOD �
0 o MAX. i 2% 2% 11.5 MAX Axi 2q, 2q, �MA MAX. I 2% 2q, , 1.5 MAX. FENCE ALDNG F I I 2�R6 2% 6%
`\\ � PROPERTY LINE w I , �,p,X MAX
EXISTING EXISTING `EXISTING of i 2" A.0 ,,poo QQQ a
0 / WEARING COURSE �) ( WEARING CDURSE a WEARING COURSE
POWER STORM GAS o ( WEARING COURSE J/ 2" A.0 1D" WATER MAIN .11�-IXI 2" A.0 2" A.0
w m 2" A.0 12" STDRM SEWER 5' 1D' 7' BEARING CDURSE
EXISTING EXISTING BEARING COURSE 1D" WATER MAN B' 5 5' B' BEARING CDURSE 6.7't 3.3't BEARING CDURSE
CABLE WATER iD" WATER MAIN 5.4't 4.3't 6" CRUSHED ROCK
12" STDRM S R 6" CRUSHED ROCK 6" CRUSHED RDCK 6" CRUSHED ROCK
NOTE; EXISTING UTILITY DEPTHS ARE ASSUMED SUBGRADE SUBGRADE SUBGRADE B" SANITARY SEWER SUBGRADE
GRANT AVENUE 12" STDRM SEWER B" SANITARY SEWER 12" STORM SEWER 1D" WATER MAIN
CROSS
ROM PAVEMENT THICKNESS PER COR 4-6-D6D.F.5 ROM PAVEMENT THICKNESS PER COR 4-6-D6D.F.5 NOTE: PAVEMENT THICKNESS PER CDR 4-6-D6D.F.5 NOTE" PAVEMENT THICKNESS PER COR 4-6-D60.F.5
CROSS SECTION A FINAL PAVEMENT THICKNESSES PENDING FINAL PAVEMENT THICKNESSES PENDING FINAL PAVEMENT THICKNESSES PENDING FINAL PAVEMENT THICKNESSES PENDING
SCALE. T-V GEOTECHNICAL ENGINEER'S REPORT GEOTECHNICAL ENGINEER'S REPORT GEOTECHNICAL ENGINEER'S REPORT GEOTECHNICAL ENGINEER'S REPORT
1D' GRANT CIRCLE S.E. (PUBLIC ALLEY) PUBLIC ALLEY GRANT CIRCLE (PUBLIC ALLEY) GRANT CIRCLE (PUBLIC ALLEY)
TEMPORARY CROSS SECTION C CROSS SECTION D CROSS SECTION E CROSS SECTION F
CONSTRUCTION SCALE T-V SCALE T-V SCALE T-90' SCALE T-10'
EASEMENT
FROM PSE .5' 2D.5' PUBLIC R.O.W. 3'
1D'
z TEMPDRARY
�I L2D' TRAVELLED WAY v CONSTRUCTION
w
EASEMENT
1n FROM PSE 22.35' w
31 oI I 1D' 1D' I, z i z 5.83' 4' VARIES z
Mqk ai i' Ij�' Z 1 z 4' 15.5'
0
CURB I irl N B.D' lir
4' MAX. HIGH wI I 2% 2% Ia R-391008
NEW ROCKERY 3 0 0 0 0__-
SEE SHT C14 I i I Mqk. a� 3 3 _, a APPROVED FOR CONSTRUCTION
FOR DETAIL 2" A.0 W
WEARING CDURSE B% B% I SUBJECT TO ERRORS AND OMISSIONS
4' 4' MAX. HIGH c
12" STORM SEWER 2 A.0 NEW RDCKERY I 1.5% MAX. MAX. 1.5q, I G
1D" WATER MAIN BEARING COURSE I 4' MAX. HIGH
5' 1D' 7' SEE SHT C14
6" CRUSHED RDCK NEW ROCKERIES BY: DATE.
SUBGRADE FOR DETAIL I I SEE SHT C14 =
B" SANITARY SEWER 4" CONCRETE z
FINAL; PAVEMENT THICKNESS PER CON 4-6-D6D.F.5 4" CDNCRETE SIDEWALK FOR DETAIL BY: DATE:
FINAL PAVEMENT THICKNESSES PENDING SIDEWALK
GEOTECHNICAL ENGINEER'S REPORT
GRANT CIRCLE S.E. (PUBLIC ALLEY) DATE: O
CROSS SECTION G CROSS SECTION H BY: DATE: Uj
CROSS SEC ON B oS�Po M yDAAF SCALE10' T-SCALE T-V
SST-V Q
Pacific 9 ' lJJJ o J. 11oFFFR �n .� wn,:n?..
ti CITY OF GRANT PLACE TOWNHOMES 2016-12-2
RENTON em z
PJ i7 Design, �' `sf �15RE 6\�� 2 SECOND ROUND CITY REVIEW COMMENTS JF 4 JH "�` E. L �__ __ __ DATUM z
Civil Engineering 1 /oNAL Ei' �-I/I� 1 FIRST ROUND CITY REVIEW COMMENTS AL 1 JH =� ,cnl a� I Planning/Building/Public Works Dept. GRADING ROADWAY AND DRAINAGE PLAN <
Plaara;t➢ng onsal8�nis NO. REVISION BY DATE APPR � '0M�"tO01°M°' COB 21
(�
0
r
co
O
d'
W
07
W
2
0
2
Z
0
W
U
Q
J
D_
Z
Q
rr
0
C8 #1 (TYPE 1)
C8 #10 (TYPE 1)
STA=10+10.32, 9.0' L
STA-2+52.48, 9.0' L
RIM ELEV = 305.28
RIM ELEV = 319.05
I.E. 12" LCPE E = 302.28
I.E. 12" LCPE E = 316.05
I.E. 12" LCPE N = 302.28
I.E. 12" LCPE W = 316.05
C8 #2 TYPE I
C8 #11 TYPE I
STA=9+45.62 9.0' L
STA.=3+56.02, 9.0' L
RIM ELEV = 314.03
RIM ELEV = 327.00
I.E. 12" LCPE E = 311.03
I.E. 12" LCPE E = 324.00
I.E. 12" LCPE W = 311.03
I.E. 12" LCPE W = 324.00
C8 #3 (TYPE 1)
C8 #12 (TYPE 1)
STA=8+55.73, 9.0' L
STA.=4+61.81, 9.0' L
RIM ELEV = 317.63
RIM ELEV = 335.09
I.E. 12" LCPE E = 314.63
I.E. 12" LCPE W = 332.09
I.E. 12" LCPE W = 314.63
I.E. 12" LCPE E = 332.09
C8 TYPE I
C8 #13 TYPE I
STA=7+56.80, 9.0' L
STA. 5+00.39, 9.0' L
RIM ELEV = 324.90
RIM ELEV = 340.61
I.E. 10 LCPE E = 321.90
I.E. 12" LCPE S = 336.95
I.E. 10 LCPE W = 321.90
I.E. 12" LCPE W = 336.95
C8 #5 (TYPE 1)
C8 #14 (TYPE 11-48.0)
STA=6+48.87, 9.0' L
HICH FLOW 8YPASS
RIM ELEV = 333.60
STA.=0+54.07, 16.5' L
I.E. 12- LCPE W - - 330.59
RIM ELEV = 296.27
I.E. 12" LCPE E = 288.50
CB #6 (TYPE 1)
I.E. 12" LCPE SE = 288.50
STA: 5+47.27, 10.0' L
I.E. 12" LCPE W = 288.50
RIM ELEV = 344.33
I.E. 12" LCPE E = 341.60
C8#15 (TYPE 1) W/VANED
I.E. 12" LCPE N = 341.60
CRATE (LOCKINC)
RIM ELEV = 315.40
C8 #7 (TYPE 1)
I.E. 12" LCPE E = 312.40
STA=1+21.20, 0.0'
I.E. 12" LCPE SW = 312.40
RIM ELEV = 351.60
I.E. 10 RCP E = 348.88
CB#16 (TYPE 1) W/VANED
I.E. 10 LCPE W = 348.88
CRATE (LOCKINC)
RIM ELEV = 322.10
C8 #8 (TYPE 1)
I.E. 12" LCPE E = 319.10
STA =0+82.93, 9.0' L
I.E. 12" LCPE W = 319.10
RIM ELEV = 303.50
LE 12" LCPE E = 300.50
C8#17 (TYPE 1) W/VANEO
I.E. 12' LCPE S = 300.50
CRATE (LOCKINC)
RIM ELEV = 329.90
CB #9 (TYPE 1)
I.E. 10 LCPE E = 326.90
STA-1+65.07. 9.0' L
I.E. 12" LCPE W = 326.90
RIM ELEV = 315.53
I.E. 12" LCPE E = 312.53
I.E. 12" LCPE W = 312.53
Pacific jna�q.t'IIJj
3jj
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Punning cansujtzanzs
C8 #18 (TYPE 1) W/VANEO
GRATE (LOCKING)
STA-1+35.87 0.0'
RIM ELEV = 355.00
I.E. 12" RCP W = 350.00
STORMMLTER MANHOLE
SFMH#1 (TYPE 11 72 0)
STA.=0+63.24 8.4' L
RIM ELEV = 300.56
I.E. 12" LCPE SE=290.87
I.E. 12" LCPE W = 288.57
W/3-18- HICH (7.5 CPM PER
CARTRIOGE) CSF CARTRIOCES
EX. SOMH-1 2 TYPE
( ) W /
souo uo
STA-0+16.15, 48.4' L
RIM ELEV = 294.54
I.E. 12- LCPE E (NEW)=287.34
I.E. 12' EX CMP N = 290.00
I.E. 12" EX CMP NE = 289.90
I.E. 12" EX CMP SE = 287.10
I.E. 15" CMP W = 286.60
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Part C Performance Standards
The site is located in Duration Flow Control Area (Forest existing condition). Since no
problem has been identified within the site and its downstream area, level 2 flow control
(forest existing condition) is required. Since the project is a multi -family development,
Enhanced basic water quality treatment is required.
Per SWDM section 1.2.3.3 and 5.2, Flow Control BMPs are required for the onsite
development. Since this project is a PUD with individual lots, applying Flow control BMP's
for more than 10% of each lot area is required. The feasibility and applicability of full
dispersion is studied first, the study found full dispersion is not suitable for this site to fully
disperse the new impervious areas and new non-native pervious areas because long
native flow path is not available due to the high impervious area ratio. Full infiltration is
also not suitable for this site because onsite soil is till soil (Alderwood gravelly sandy loam,
6 to 15% slopes, AgC and 15% to 25% slopes, AgD) according to City of Renton Soils
Map.
The following flow control BMPs are used:
1. Native growth retention area (TRACT C, 2,595 square feet, counted as pasture
area). Impervious area credit allowed by this BMP is 2,595/3.5 = 741 square feet
per section C 2.10 of Appendix C of 2009 KCSWDM.
2. Pervious concrete walkway (4" pervious concrete on 2" choker course on 4"
aggregate base, with 2 to 5% slope) for all onsite sidewalks (8,976 square feet,
credited as 50% impervious area, 50% grass).
3. Grasscrete pavement (4" grasscrete, on 2" choker course on 6" crushed stone
base) for vault maintenance access driveway (1972 square feet, credited as 50%
impervious area, 50% grass)
4. Perforated tie lines for downspout connections. (no credit)
Total impervious area treated by flow control BMPs is 11,689 square feet which is
approximately 32.8% (> 10% of the total lot areas of the 36 zero lot line lots (total 35,630
square feet which is 3,563 square feet). Final signed Flow Control BMP Covenant is
required prior permit is issued and will be recorded with the PUD Plat map.
Onsite flow control facility is provided by a combined detention/wet vault to provide the
required.
For onsite improvement, the proposed project will use 10 feet minimum perforated
downspout connection for each building, use a combined detention/wet vault to provide
the required Duration standard forested site conditions flow control at the point of
convergence (at SDMH#1 at Grant Avenue South) and use a treatment train of wet
vault and StormFilter manhole with CSF cartridges to provide the required Enhanced
Basic water quality treatment. Treated runoff will be discharged to its natural
discharged location (SDMH#1 at Grant Avenue South).
See Section 2 of this report regarding special requirements, the only special
requirement applicable to this site is special requirement 1.3.4 for source control.
Dumpsters and recycle bins will be stored in the garages of each units. Since the site is
not a high use site, oil control is not required.
27
The new onsite conveyance system (the pipes are minimum 12-inch diameter LCPE
pipes with minimum slopes of 0.5%) is designed per chapter 4 of the City of Renton
Amendments to the 2009 KCSWDM to convey the 25-year peak with 6 inches of free
board and the 100-year peak flows.
For offsite frontage improvement, as discussed in Section 1 of this report, no flow
control or water quality treatment is required
28
Part D Flow Control System
Flow control facility:
A combined detention/wet vault is used to provide the required Level 2 flow control
(forest existing condition) at the point of convergence. The offsite frontage improvement
is counted as bypassed areas. KCRTS method is used to size the detention system.
Retention/Detention Facility
Type of Facility:
Facility Length:
Facility Width:
Facility Area:
Effective Storage Depth:
Stage 0 Elevation:
Storage Volume:
Riser Head:
Riser Diameter:
Number of orifices:
Detention Vault
90.00 ft
40.00 ft
3600. sq. ft
7.95 ft
0.00 ft
28620. cu. ft
7.95 ft
12.00 inches
3
Full Head Pipe
Orifice
# Height
Diameter
Discharge
Diameter
(ft)
(in)
(CFS)
(in)
1
0.00
0.68
0.035
2
4.65
1.25
0.078
4.0
3
7.20
1.00
0.024
4.0
Top Notch Weir:
None
Outflow
Rating Curve:
None
Stage
Elevation
Storage
Discharge
Percolation
(ft)
(ft) (cu. ft) (ac-ft)
(cfs)
(cfs)
0.00
0.00
0.
0.000
0.000
0.00
0.01
0.01
36.
0.001
0.001
0.00
0.02
0.02
72.
0.002
0.002
0.00
0.03
0.03
108.
0.002
0.002
0.00
0.04
0.04
144.
0.003
0.003
0.00
0.05
0.05
180.
0.004
0.003
0.00
0.06
0.06
216.
0.005
0.003
0.00
0.21
0.21
756.
0.017
0.006
0.00
0.37
0.37
1332.
0.031
0.008
0.00
0.52
0.52
1872.
0.043
0.009
0.00
0.68
0.68
2448.
0.056
0.010
0.00
0.84
0.84
3024.
0.069
0.011
0.00
0.99
0.99
3564.
0.082
0.012
0.00
1.15
1.15
4140.
0.095
0.013
0.00
1.30
1.30
4680.
0.107
0.014
0.00
1.46
1.46
5256.
0.121
0.015
0.00
1.62
1.62
5832.
0.134
0.016
0.00
1.77
1.77
6372.
0.146
0.017
0.00
1.93
1.93
6948.
0.160
0.017
0.00
2.08
2.08
7488.
0.172
0.018
0.00
2.24
2.24
8064.
0.185
0.019
0.00
2.39
2.39
8604.
0.198
0.019
0.00
2.55
2.55
9180.
0.211
0.020
0.00
2.71
2.71
9756.
0.224
0.021
0.00
2.86
2.86
10296.
0.236
0.021
0.00
3.02
3.02
10872.
0.250
0.022
0.00
3.17
3.17
11412.
0.262
0.022
0.00
3.33
3.33
11988.
0.275
0.023
0.00
3.49
3.49
12564.
0.288
0.023
0.00
3.64
3.64
13104.
0.301
0.024
0.00
3.80
3.80
13680.
0.314
0.024
0.00
Me
3.95
3.95
14220.
0.326
0.025
0.00
4.11
4.11
14796.
0.340
0.025
0.00
4.27
4.27
15372.
0.353
0.026
0.00
4.42
4.42
15912.
0.365
0.026
0.00
4.58
4.58
16488.
0.379
0.027
0.00
4.65
4.65
16740.
0.384
0.027
0.00
4.66
4.66
16776.
0.385
0.027
0.00
4.68
4.68
16848.
0.387
0.028
0.00
4.69
4.69
16884.
0.388
0.030
0.00
4.70
4.70
16920.
0.388
0.032
0.00
4.72
4.72
16992.
0.390
0.035
0.00
4.73
4.73
17028.
0.391
0.039
0.00
4.74
4.74
17064.
0.392
0.040
0.00
4.75
4.75
17100.
0.393
0.041
0.00
4.91
4.91
17676.
0.406
0.049
0.00
5.07
5.07
18252.
0.419
0.056
0.00
5.22
5.22
18792.
0.431
0.061
0.00
5.38
5.38
19368.
0.445
0.065
0.00
5.53
5.53
19908.
0.457
0.069
0.00
5.69
5.69
20484.
0.470
0.073
0.00
5.85
5.85
21060.
0.483
0.077
0.00
6.00
6.00
21600.
0.496
0.080
0.00
6.16
6.16
22176.
0.509
0.083
0.00
6.31
6.31
22716.
0.521
0.086
0.00
6.47
6.47
23292.
0.535
0.089
0.00
6.62
6.62
23832.
0.547
0.092
0.00
6.78
6.78
24408.
0.560
0.095
0.00
6.94
6.94
24984.
0.574
0.097
0.00
7.09
7.09
25524.
0.586
0.100
0.00
7.20
7.20
25920.
0.595
0.101
0.00
7.21
7.21
25956.
0.596
0.102
0.00
7.22
7.22
25992.
0.597
0.102
0.00
7.23
7.23
26028.
0.598
0.104
0.00
7.24
7.24
26064.
0.598
0.105
0.00
7.25
7.25
26100.
0.599
0.107
0.00
7.26
7.26
26136.
0.600
0.109
0.00
7.27
7.27
26172.
0.601
0.110
0.00
7.28
7.28
26208.
0.602
0.110
0.00
7.29
7.29
26244.
0.602
0.111
0.00
7.45
7.45
26820.
0.616
0.119
0.00
7.61
7.61
27396.
0.629
0.125
0.00
7.76
7.76
27936.
0.641
0.130
0.00
7.92
7.92
28512.
0.655
0.135
0.00
7.95
7.95
28620.
0.657
0.136
0.00
8.05
8.05
28980.
0.665
0.447
0.00
8.15
8.15
29340.
0.674
1.010
0.00
8.25
8.25
29700.
0.682
1.740
0.00
8.35
8.35
30060.
0.690
2.540
0.00
8.45
8.45
30420.
0.698
2.820
0.00
8.55
8.55
30780.
0.707
3.080
0.00
8.65
8.65
31140.
0.715
3.320
0.00
8.75
8.75
31500.
0.723
3.540
0.00
8.85
8.85
31860.
0.731
3.750
0.00
8.95
8.95
32220.
0.740
3.940
0.00
9.05
9.05
32580.
0.748
4.130
0.00
9.15
9.15
32940.
0.756
4.310
0.00
9.25
9.25
33300.
0.764
4.480
0.00
9.35
9.35
33660.
0.773
4.640
0.00
9.45
9.45
34020.
0.781
4.800
0.00
9.55
9.55
34380.
0.789
4.960
0.00
9.65
9.65
34740.
0.798
5.110
0.00
9.75
9.75
35100.
0.806
5.250
0.00
Hyd Inflow
Outflow
Peak
Storage
Stage
Elev
(Cu-Ft)
(Ac-Ft)
im
1 0.81 0.26 7.99 7.99 28761. 0.660
2 0.40 0.13 7.66 7.66 27581. 0.633
3 0.48 0.09 6.58 6.58 23696. 0.544
4 0.52 0.09 6.51 6.51 23428. 0.538
5 0.42 0.06 5.29 5.29 19055. 0.437
6 0.43 0.04 4.76 4.76 17147. 0.394
7 0.33 0.03 4.67 4.67 16824. 0.386
8 0.36 0.02 2.99 2.99 10776. 0.247
Hyd R/D Facility Tributary Reservoir POC Outflow
Outflow Inflow Inflow Target Calc
1 0.26 0.02 ******** 0.17 0.26
2 0.13 0.01 ******** ******* 0.13
3 0.09 0.01 ******** 0.10 0.09
4 0.09 0.01 ******** ******* 0.09
5 0.06 0.01 ******** ******* 0.07
6 0.04 0.01 ******** 0.06 0.04
7 0.03 0.01 ******** ******* 0.03
8 0.02 0.01 ******** ******* 0.03
----------------------------------
Route Time Series through Facility
Inflow Time Series File:dev.tsf
Outflow Time Series File:rdout
POC Time Series File:ddout
Inflow/Outflow Analysis
Peak Inflow Discharge:
0.806
CFS
at 6:00 on Jan 9 in Year 8
Peak Outflow Discharge:
0.258
CFS
at 11:00 on Jan 9 in Year 8
Peak Reservoir Stage:
7.99
Ft
Peak Reservoir Elev:
7.99
Ft
Peak Reservoir Storage:
28761.
Cu-Ft
0.660
Ac-Ft
Add Time Series:offsite.tsf
Peak Summed Discharge: 0.263 CFS at 11:00 on Jan 9 in Year 8
Point of Compliance File:dsout.tsf
Flow Frequency Analysis
Time Series File:rdout.tsf
Project Location:Sea-Tac
---Annual
Peak
Flow Rates ---
Flow Rate
Rank
Time of
Peak
(CFS)
0.127
2
2/09/01
20:00
0.028
7
1/07/02
4:00
0.091
3
3/06/03
22:00
0.022
8
8/26/04
8:00
0.042
6
1/08/05
3:00
0.063
5
1/19/06
0:00
0.090
4
11/24/06
8:00
0.258
1
1/09/08
11:00
Computed Peaks
Flow Frequency Analysis
Time Series File:dsout.tsf
Project Location:Sea-Tac
---Annual
Peak
Flow Rates ---
Flow Rate
Rank
Time of
Peak
(CFS)
0.130
2
2/09/01
20:00
0.031
7
1/05/02
16:00
0.094
3
3/06/03
21:00
0.027
8
8/26/04
2:00
0.043
6
1/08/05
2:00
-----Flow
Frequency
Analysis-------
- - Peaks
- -
Rank Return
Prob
(CFS)
(ft)
Period
0.258
7.99
1
100.00
0.990
0.127
7.66
2
25.00
0.960
0.091
6.58
3
10.00
0.900
0.090
6.51
4
5.00
0.800
0.063
5.29
5
3.00
0.667
0.042
4.76
6
2.00
0.500
0.028
4.67
7
1.30
0.231
0.022
2.99
8
1.10
0.091
0.214
7.98
50.00
0.980
-----Flow Frequency Analysis-------
- - Peaks -
- Rank
Return
Prob
(CFS)
Period
0.263
1
100.00
0.990
0.130
2
25.00
0.960
0.094
3
10.00
0.900
0.093
4
5.00
0.800
0.065
5
3.00
0.667
31
0.065
5
1/18/06
23:00
0.043
6 2.00
0.500
0.093
4
11/24/06
7:00
0.031
7 1.30
0.231
0.263
1
1/09/08
11:00
0.027
8 1.10
0.091
Computed
Peaks
0.218
50.00
0.980
Flow Duration
from Time
Series File:rdout.tsf
Cutoff
Count
Frequency CDF
Exceedence_Probability
CFS
o
%
%
0.002
28152
45.910
45.910
54.090
0.541E+00
0.005
7792
12.707
58.617
41.383
0.414E+00
0.009
6633
10.817
69.434
30.566
0.306E+00
0.013
6874
11.210
80.644
19.356
0.194E+00
0.016
4170
6.800
87.445
12.555
0.126E+00
0.020
3501
5.709
93.154
6.846
0.685E-01
0.023
2006
3.271
96.425
3.575
0.357E-01
0.027
1574
2.567
98.992
1.008
0.101E-01
0.030
198
0.323
99.315
0.685
0.685E-02
0.034
16
0.026
99.341
0.659
0.659E-02
0.037
8
0.013
99.354
0.646
0.646E-02
0.041
19
0.031
99.385
0.615
0.615E-02
0.044
42
0.068
99.454
0.546
0.546E-02
0.048
32
0.052
99.506
0.494
0.494E-02
0.051
39
0.064
99.569
0.431
0.431E-02
0.055
31
0.051
99.620
0.380
0.380E-02
0.059
33
0.054
99.674
0.326
0.326E-02
0.062
25
0.041
99.715
0.285
0.285E-02
0.066
30
0.049
99.764
0.236
0.236E-02
0.069
17
0.028
99.791
0.209
0.209E-02
0.073
16
0.026
99.817
0.183
0.183E-02
0.076
11
0.018
99.835
0.165
0.165E-02
0.080
14
0.023
99.858
0.142
0.142E-02
0.083
16
0.026
99.884
0.116
0.116E-02
0.087
15
0.024
99.909
0.091
0.913E-03
0.090
16
0.026
99.935
0.065
0.652E-03
0.094
10
0.016
99.951
0.049
0.489E-03
0.097
12
0.020
99.971
0.029
0.294E-03
0.101
5
0.008
99.979
0.021
0.212E-03
0.104
1
0.002
99.980
0.020
0.196E-03
0.108
1
0.002
99.982
0.018
0.179E-03
0.112
1
0.002
99.984
0.016
0.163E-03
0.115
2
0.003
99.987
0.013
0.130E-03
0.119
1
0.002
99.989
0.011
0.114E-03
0.122
2
0.003
99.992
0.008
0.815E-04
0.126
3
0.005
99.997
0.003
0.326E-04
Flow Duration from Time
Series File:dsout.tsf
Cutoff
Count
Frequency CDF
Exceedence_Probability
CFS
o
%
%
0.002
28141
45.892
45.892
54.108
0.541E+00
0.005
7745
12.630
58.523
41.477
0.415E+00
0.009
6603
10.768
69.291
30.709
0.307E+00
0.013
6777
11.052
80.342
19.658
0.197E+00
0.016
4416
7.202
87.544
12.456
0.125E+00
0.020
3369
5.494
93.038
6.962
0.696E-01
0.024
1945
3.172
96.210
3.790
0.379E-01
0.027
1641
2.676
98.886
1.114
0.111E-01
0.031
244
0.398
99.284
0.716
0.716E-02
0.035
34
0.055
99.340
0.660
0.660E-02
0.038
9
0.015
99.354
0.646
0.646E-02
0.042
21
0.034
99.388
0.612
0.612E-02
0.046
43
0.070
99.459
0.541
0.541E-02
0.049
33
0.054
99.512
0.488
0.488E-02
0.053
37
0.060
99.573
0.427
0.427E-02
0.056
28
0.046
99.618
0.382
0.382E-02
0.060
34
0.055
99.674
0.326
0.326E-02
32
0.064
24
0.039
99.713
0.287
0.287E-02
0.067
29
0.047
99.760
0.240
0.240E-02
0.071
20
0.033
99.793
0.207
0.207E-02
0.075
15
0.024
99.817
0.183
0.183E-02
0.078
10
0.016
99.834
0.166
0.166E-02
0.082
15
0.024
99.858
0.142
0.142E-02
0.086
17
0.028
99.886
0.114
0.114E-02
0.089
11
0.018
99.904
0.096
0.962E-03
0.093
19
0.031
99.935
0.065
0.652E-03
0.096
9
0.015
99.949
0.051
0.506E-03
0.100
13
0.021
99.971
0.029
0.294E-03
0.104
4
0.007
99.977
0.023
0.228E-03
0.107
2
0.003
99.980
0.020
0.196E-03
0.111
1
0.002
99.982
0.018
0.179E-03
0.115
1
0.002
99.984
0.016
0.163E-03
0.118
1
0.002
99.985
0.015
0.147E-03
0.122
2
0.003
99.989
0.011
0.114E-03
0.126
2
0.003
99.992
0.008
0.815E-04
0.129
3
0.005
99.997
0.003
0.326E-04
Duration
Comparison
Anaylsis
Base
File: pre.tsf
New
File: dsout.tsf
Cutoff Units: Discharge
in
CFS
-----Fraction
of
Time -----
---------Check
of Tolerance-------
CutoffBase
New
%Change
Probability Base
New %Change
0.030
0.95E-02
0.75E-02
-21.4
I 0.95E-02
0.030
0.028 -6.9
0.038
I 0.64E-02
0.65E-02
1.5
I 0.64E-02
0.038
0.040 4.7
0.046
I 0.50E-02
0.53E-02
7.6
0.50E-02
0.046
0.049 5.6
0.055
0.37E-02
0.40E-02
8.8
I 0.37E-02
0.055
0.057 5.2
0.063
0.29E-02
0.30E-02
4.0
0.29E-02
0.063
0.064 1.8
0.071
0.22E-02
0.21E-02
-6.6
0.22E-02
0.071
0.069 -2.7
0.079
0.15E-02
0.16E-02
5.5
0.15E-02
0.079
0.080 1.3
0.087
0.10E-02
0.10E-02
1.6
I 0.10E-02
0.087
0.088 0.3
0.096
I 0.62E-03
0.52E-03
-15.8
I 0.62E-03
0.096
0.094 -1.9
0.104
0.34E-03
0.23E-03
-33.3
I 0.34E-03
0.104
0.099 -4.6
0.112
( 0.21E-03
0.18E-03
-15.4
I 0.21E-03
0.112
0.107 -4.6
0.120
0.16E-03
0.11E-03
-30.0
I 0.16E-03
0.120
0.116 -3.6
0.129
0.11E-03
0.49E-04
-57.1
I 0.11E-03
0.129
0.123 -4.6
0.137
0.16E-04
0.00E+00
-100.0
0.16E-04
0.137
0.130 -4.9
Maximum positive excursion = 0.003 cfs ( 7.4%)
occurring at 0.038 cfs on the Base Data:pre.tsf
and at 0.041 cfs on the New Data:dsout.tsf
Maximum negative excursion = 0.004 cfs (-12.8%)
occurring at 0.034 cfs on the Base Data:pre.tsf
and at 0.030 cfs on the New Data:dsout.tsf
33
d-9 d.,
o
10 1 lo, 10 -1 10 1 10 -1 10,
Probability Exceedence
Predeveloped duration VS developed duration at point of convergence
Retum Period
I I Io inn
C.m.I.M. Probability
Predeveloped peaks VS developed peaks at point of convergence
34
The hydrograph of the onsite detained runoff (detention vault release, include the 0.22
acre upstream tributary area, rdout.tsf) will be added with the hydrograph of the offsite
bypass area (Grant Avenue South frontage improvement, offsite.tsf). The combined
hydrograph (dsout.tsf) is used to compare with the existing hydrograph of the total
combined site (including onsite area 2.11 acres, upstream tributary area 0.22 acres and
Grant Avenue South frontage improvement area 0.06 acres, total 2.39 acres, pre.tsf) at
the point of compliance at existing storm manhole SDMH#1 at Grant Avenue South to
meet the requirements of Level 2 detention.
Peak combined detention/wet vault release rate (rdout.tsf):
Q2y = 0.042 cfs
Q10y = 0.091 cfs
Q100y = 0.258 cfs
Peak developed peak flows at point of compliance (dsout.tsf):
Due to the peak shift effect of the detention vault the dsout.tsf peaks are less than the
sum of the rdout.tsf peaks plus the offsite.tsf peaks.
Hydrograph dsout,tsf = hydrograph rdout.tsf + hydrograph offsite.tsf
Peaks dsout.tsf < peaks rdout.tsf + peaks offsite.tsf
Q2y = 0.043 cfs < 0.071 cfs (existing site condition, pre.tsf), o.k.
Q10y = 0.094 cfs < 0.124 cfs (existing site condition, pre.tsf), o.k.
Q100y = 0.263 cfs.
The proposed combined detention/wet vault (90' L x 40' W x 8' H live storage) provides
28,800 cubic feet of live storage. Required live storage is 28,761 cubic feet for the 100
year peak flow, o.k.
Two flow control devices are used inside the vault. One is an 8" tee with shear gate, a
0.68" bottom orifice, a solid top and an 8" outfall pipe to the StormFilter manhole which
controls the under 2-year flow to the StormFilter manhole, the other is a 12" riser for
over 2-year flow control. The 12" riser has a 1.25" bottom orifice (used as the 2nd
orifice) and a V orifice at a 4" elbow (used as the 3rd orifice), the top of the riser is used
for overflow for over 100 year storm event. The 12" outfall pipe for the 12" flow control
riser is connected to a type 2 catch basin bypassing the StormFilter manhole. The vault
also has an 8" outfall with shear gate for maintenance dewatering.
Use KCRTS method with 15 minute time step to calculate 100 year peak overflow for
the detention system.
92
40 Land Use Summary
-,area ____.—_�
Till Forest! 0.00 acres
i
Till Pasturei 0.00 acres'
Till Grassi 0.73 acres!
Outwash Forest 0.00 acres
1
Outwash Pasture 0.00 acres
Outwash Grass` 0.00 acres!
Wetland 0.00 acres
Impervious) 1.30 acres;
-Total---I Y�
2.11 acres
Scale Factor: 1.00 15-F in Reduced
Edit Flows Paths
Time Series: dev-15.tsf »,
Compute Time Series
Modify User Input
File for computed Time Series [.TSF]
Flow Frequency Analysis
Time Series File:dev-15.tsf
Project Location:Sea-Tac
---Annual
Peak
Flow Rates ---
Flow Rate
Rank
Time of
Peak
(CFS)
0.657
6
8/27/01
18:00
0.464
8
1/05/02
15:00
1.41
2
12/08/02
17:15
0.529
7
8/23/04
14:30
0.791
4
11/17/04
5:00
0.783
5
10/27/05
10:45
0.916
3
10/25/06
22:45
2.00
1
1/09/08
6:30
Computed Peaks
-----Flow
Frequency
Analysis -------
- - Peaks
- - Rank Return
Prob
(CFS)
Period
2.00
1
100.00
0.990
1.41
2
25.00
0.960
0.916
3
10.00
0.900
0.791
4
5.00
0.800
0.783
5
3.00
0.667
0.657
6
2.00
0.500
0.529
7
1.30
0.231
0.464
8
1.10
0.091
1.80
50.00
0.980
Q100y overflow = 2.00 cfs
12" riser overflow capacity with head = 0.35'
Q orifice = 3.728 * D** (2) * H ** (1/2) = 3.728 * 1 * 0.35 ** (1/2) = 2.21 cfs > 2.00 cfs,
o. k.
The 12" riser has the capacity to handle the 100 year overflow.
36
Since the vault is located at a sloped area, fill over the top of the vault varies from 0.5 to
85, engineering foam (Geofoam EPS46 or equal) is used to reduce the weight loading
to the top of the vault. A service driveway is provided to access to the two 5'x10' grate
openings and other manhole covers. The driveway is designed to support the weight of
a vactor truck (60,000 pounds).
At the southeast corner of the vault, there is up to 8.5' of fill over the top of the vault.
Each Geofoam block is approximately 6' or 8' long x 4' wide x 1" to 3' high. Use 2 row
of Geofoam 3' high blocks and 2.5' of soil on top of the Geofoam blocks. Assume a
person with 300 pounds of weight is standing on top of the ground and the person's
weight is distributed in a 2 square feet area. Density of the Geofoam EPS46 is 2.85
lb/cf. Soil density is 100 lb/cf. Total loading in a square feet area = 300/2 + 6 * 2.85 +
2.5 * 100 = 417.1 pounds. Compressive resistance of the Geofoam EPS 46 is 18.6 psi
= 2,678.4 pounds/square feet at 1 % deformed which is larger than 417.1 pounds, o.k.
4" perforated footing drain will be used near the bottom of the Geofoam blocks to
directed ground water to the vault to prevent buoyancy problem.
For the service driveway on top of the vault, asphalt pavement is used for the north
portion of the driveway (4" min. HMA class 0.5" on 6" min. crushed surface top course)
and grasscrete is used for the south portion of the driveway as a Flow control BMP (4"
thick grasscrete, on 2" choker course on 6" crushed stone base). Minimum 2' of cover
is provided between the top of the driveway to the top of the Geofoam blocks. Rear
axle loading of the 60,000 pounds vactor truck is 40,000 pounds. Assume this load (8
tires) is distributed in a 5'x5' area by the time the load reaches the Geofoam blocks.
Total loading in a square feet area = 40,000/25 = 1,600 pounds. Compressive
resistance of the Geofoam EPS 46 is 18.6 psi = 2,678.4 pounds/square feet at 1 %
deformed which is larger than 1,600 pounds, o.k.
Inside dimension of the vault is 90'Lx40'W (in two 20' wide cells separated by a
structural wall) x 13.5' H (minimum average) to provide 8' deep live storage, 4' deep
dead storage, 0.5' minimum freeboard and 1' minimum average sediment storage.
Outside dimension of the vault is 921 x 43'W x 15.5' H (minimum average). The vault is
designed to support the H-20 traffic loading. The majority of the vault including to two
5'x10' grated access openings are located outside the traffic paths. Only the northeast
corner of the vault (with two 48" diameter access manholes and 24" diameter solid
locking covers) is located in a parking area. Minimum 5' setback to the Grant Avenue
South Right of way and minimum 10' setback to the closest building are provided.
Vault design criteria per 2009 KCSWDM 5.3.3 is met with this design.
Access requirements:
1. Two 5'x10' grated accesses and five 24" diameter solid locking covers are
provided. Access openings are available within 50 feet from any location inside
the vault.
2. 5'x10' removable grated accesses are provided one for each cells of the vault.
3. Both 5'x10' accesses are located outside traffic paths. Two 24" diameter solid
locking manhole covers are provided in the parking area. Access ladders and
hand -holds are provided at inlet and outlet pipe locations.
37
III
A
CONTROL
022:
Foam -Control Geofoam is a cellular plastic material that
is strong, but has very low density (1% of traditional earth
materials). It is a manufactured in block form and meets
ASTM D6817, "Standard Specification for Rigid, Cellular
Polystyrene Geofoam." Foam -Control Geofoam is available
in a range of Types to provide control of structural integrity
and cost effectiveness.
The information given is deemed to be timely, accurate, and
reliable for the use of Foam -Control Geofoam. Each project
using Foam -Control Geofoam should be designed by a
professional engineer. The engineer or project specifications
should be consulted to determine the ASTM D6817 Type
required for your project loading conditions.
Foam -Control Geofoam Properties
ASTM D6817
Property
EPS12
EPS15
EPS19
EPS22
EPS29
EPS39
EPS46
Density', min.
Ib/ft3
0.70
0.90
1.15
1.35
1.80
2.40
2.85
(kg/m3)
(11.2)
(14.4)
(18.4)
(21.6)
(28.8)
(38.4)
(45.7)
Compressive Resistance12
psi
2.2
3.6
5.8
7.3
10.9
15.0
18.6
@ 1% deformation, min.
psf
320
520
840
1050
1570
2160
2680
(kPa)
(15)
(25)
(40)
(50)
(75)
(103)
(128)
Elastic Modulus',
psi
220
360
580
730
1090
1500
1860
min
(kPa)
(1500)
(2500)
(4000)
(5000)
(7500)
(10300)
(12800)
Flexural Strength',
psi
10.0
25.0
30.0
35.0
50.0
60.0
75.0
min.
(kPa)
(69)
(172)
(207)
(240)
(345)
(414)
(517)
Water Absorption' by
Vol. %
4.0
4.0
3.0
3.0
2.0
2.0
2.0
total immersion, max.,
Oxygen Index', min.
Vol. %
24
24
24
24
24
24
24
Buoyancy Force
Ib/ft3
61.7
61.5
61.3
61.1
60.6
60.0
59.5
(kg/m3)
(990)
(980)
(980)
(980)
(970)
(960)
(950)
' See ASTM D6817 Standard for test methods and complete information.
2 Combined live and dead load stresses should not exceed the compressive resistance at 1% deformation.
Foam -Control Geofoam is used in ground fill
applications where a lightweight fill material
is required to reduce stresses on underlying or
adjoining soils/structures.
Ready to Use.
Foam -Control Geofoam maximizes onsite installation
efficiency: material arrives ready to place, no weather delays,
material can be prefabricated or cut at the jobsite, no staging
required, material can be inventoried, production efficiency
improved, and it is easy to handle.
Design Loads.
For most applications, long-term design loads should not
exceed the linear elastic range of Foam -Control Geofoam.
Combined live and dead load stresses should not exceed the
compressive resistance at 1% deformation.
In some specialty compressible applications, the compressive
resistance at 5% and 10% deformation may be applicable.
Please consult Foam -Control Geofoam Technical Bulletins
for additional information.
In general earthwork applications (such as levees, dikes,
berms, etc.) uplift buoyancy force must be counteracted
with overburden or restraint devices, such as geogrids,
geomembranes, hold down devices, etc.
Size and Shape.
Foam -Control Geofoam is produced in block form and is
easily positioned at the work site. Standards sizes:
• 4' (1.2 m) widths
• 8' (2.4 m) up to 16' (4.8 m) lengths
• 1" (25 mm) to 36" (914 mm) thickness
Other sizes and fabrication can be provided by the
manufacturer.
Exposure to Water and Water Vapor.
The mechanical properties of Foam -Control Geofoam are
unaffected by moisture. Exposure to water or water vapor
does not cause swelling.
Temperature Exposure/Flame Retardants.
Foam -Control Geofoam is able to withstand the rigors of
temperature cycling, assuring long-term performance.
Although flame retardants used in the manufacture of
Foam -Control Geofoam provide an important margin
of safety, Foam -Control Geofoam must be considered
combustible.
The maximum recommended long-term exposure
temperature for Foam -Control Geofoam is 165°F (74oC).
Adhesives, Coatings, and Chemicals.
Solvents which attack Foam -Control Geofoam include esters,
ketones, ethers, aromatic, and aliphatic hydrocarbons and
their emulsions, among others. If Foam -Control Geofoam
is to be placed in contact with materials (or their vapors) of
unknown composition, pretest for compatibility at maximum
exposure temperature.
Quality Assurance.
Foam -Control Geofoam meets or exceeds
the requirements of ASTM D6817, "Standard ASSIt&
Specification for Rigid, Cellular Polystyrene UL
Geofoam" Foam -Control Geofoam is monitored
for Quality Control and Listed by Underwriters
Laboratories Inc.
Resistance to Termites, Mold, and Mildew.
Foam plastics have been shown to become termite
infested under certain exposure conditions. Foam -Control
Geofoam with Perform Guard'
provides resistance to termite OPerfformGuard'
E RESISTANT
infestation. Please review literature on
Foam -Control Geofoam with Perform
Guard for complete information.
Foam -Control Geofoam will not decompose and will not
support mold or mildew growth. Foam -Control Geofoam
provides no nutrient value to plants or animals.
Storage and Ballast.
Foam -Control Geofoam stands up well to normal short-term
weather conditions encountered during installation.
Long-term exposure to sunlight causes yellowing and a
slight embrittlement of the surface due to ultraviolet light.
This has little effect on mechanical properties. If stored
outdoors, cover Foam -Control Geofoam with opaque
polyethylene film, tarps, or similar material.
Foam -Control Geofoam should be ballasted to prevent
displacement by wind or high water conditions, both in
storage and during all phases of placement.
Warranty.
Foam -Control Geofoam Licensees offer a product warranty
ensuring physical properties.
'®
cenvexnax_ CONTROL '.
Foam -Control products are manufactured by
AFM Corporation licensees.
Copyright © 2015 AFM Corporation.
All rights reserved. Printed in USA.
Foam -Control, Perform Guard, GeoGripper,
and Control, Not Compromise are
registered trademarks of AFM Corporation,
Lakeville, MN.
ILL logo is a registered trademark of UL LLC
GF05-10/15
4. 48" diameter type 1 manholes with 24" diameter locking manhole covers are
used.
5. Not applied. The vault cells are 20' wide.
6. Maximum depth from the finished grade to the vault invert are within 20 feet.
7. A 5' wide x 7' high wall opening is provided at the south end of the separation
wall between the two cells.
8. The minimum internal height is 13.5' in average which is larger than the required
7'. Minimum internal width is 20' which is larger than the required 4'.
9. One 5'xl0' grated removable access, three 24" diameter locking manhole covers
are provided at four corners for vent.
Part E Water Quality System
On site improvement
A treatment train of combined detention/wet vault and StormFilter manhole with CSF
cartridges is used to provide the required Enhanced Basic Water Quality treatment.
The StormFilter manhole with CSF cartridges will be installed downstream of the
combined detention/wet vault. The combined detention/wet vault is also used as a
pretreatment device for the StormFilter manhole.
Wet vault sizing:
Area to be treated:
Total impervious area = 1.38 acres
Total pervious area = 0.73 acres (till grass)
Total drainage area = 2.11 acres
Mean annual volume:
Vr=(0.9*Ai+0.25*Atg+0.10*Atf+0.01 *Ao)*R
=(0.9*1.38+0.25*0.73+0.10*0+0.01 *0)*43560*0.039
= 2,420 cf.
Required dead storage = 3 * Vr = 7,260 cf.
The proposed combined detention/wet vault is separated into two cells by a concrete wall
in the middle, it provides 90'x40'x8' = 28,800 cubic feet of live storage, and 85' L x 40' W
x 4' H = 13,600 cubic feet (> 7,260 cf, o.k.) of water quality dead storage and minimum 1'
average depth of sediment storage (3,600 cubic feet).
StormFilter sizing:
Flow based sizing:
The design WQ flow is the 2 year release rate from the combined detention/wet vault
Qtreat = Q2y = 0.042 cfs = 18.86 GPM
The capacity of the standard 18" high CSF cartridge is Qcart = 7.5 GPM / cartridge
Nflow = Qtreat /Qcart = 2.51, Use 3 cartridges.
Mass loading sizing:
c:
Annual average rainfall P = 38"
Percent capture = 90%
EMC = 60 mg/L (Seattle area commercial landuse)
Area to be treated:
PGIS = 1.38 acres
PGPS = 0.73 acres (till grass)
Mean annual runoff volume:
Vt = (P in) * C * (A acres) * (43560 cf / 12 in/ft) * (% Capture)
=(38)*(0.9*1.38+0.25*0.73)*(43560/12)*0.9
= 176,846 cf.
Annual mass load:
Mtotal = (Vt cf) * (EMC mg/L) * (28.3 L/cf) * (1 E-6 kg/mg) * (2.2046 Ibs/kg)
= 176,846 * 60 * 28.3 * 1 E-6 * 2.2046
= 662 lbs.
Assume pretreatment efficiency Epre = 80% (downstream of a wet vault designed to
remove 80% TSS)
Mpre = 662 * 0.80 = 529.60 Ibs
Mpass1 = Mtotal — Mpre = 662 — 529.60 = 132.40 Ibs
Assume Filter efficiency Efilter = 72%
Mfilter = Mpass1 * E filter = 132.40 * 0.72 = 95.33 Ibs
Mass load capacity of the standard 7.5 GPM cartridge Mcart = 36 Ibs/cartridge
Nmass = Mfilter / Mcart = 95.33/36 = 2.65, Use 3 cartridges.
Use the maximum number of cartridges calculated by both flow based and mass loading
based sizing methods, three 18" high CSF cartridges with 7.5 gpm/cartridge capacity will
be used. The cartridges will be installed in a 72" diameter StormFilter manhole.
The combined detention/wet vault has two flow control devices as described in Part D,
only the under two year flows drain to the StormFilter manhole, the higher flows are
bypassed to a type 2 catch basin downstream of the StormFilter manhole. The 2 year
release from the vault is 0.042 cubic feet per second which is less than the overflow
capacity (1.5 cubic feet per second) of the StormFilter manhole.
Offsite frontage improvement
The offsite frontage improvement creates approximately 1,440 square feet of new
impervious area (520 square feet of it is pollution generating impervious area) and no
new pervious area. For flow control, the new impervious area created by the offsite
improvement is counted as bypassed target area Per KCSWDM Section 1.2.3.2.E. The
onsite detention vault is oversized, so that the developed onsite detained runoff plus the
offsite bypassed runoff meets the required Duration standard forested site conditions flow
control requirements at the point of convergence (SDMH#1 at Grant Avenue South). For
water quality treatment, new pollution generating area is only 520 square feet and is
counted as untreated discharge per KCSWDM Section 1.2.8.2.D bypassing the water
quality treatment facilities.
39
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1' MIN NATIVE
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\ SOIL BACKFlLL
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FILTER FABRIC ON TOP
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GEOFOAM BLOCKS
4• PVC VERT. PIPE
1' MIN. CEOFOAM BLOCKS
EPS46 OR EQUAL
Fi
GEOFOAM BLOCKS
EPS46 OR EQUAL
5'x10' CRATED LOCKINC
REMOVABLE ACCESS PANEL
(MARKEO GRAIN)
RIM=302.00
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4• PERF. PVC
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4• PERF. PVC
6• MIN. CRAVEL BASE
_______ _-=
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°"FRAME
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STEPS OFFSET. SEE
STEPSNOTE
=
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100-YEAR WATER SURFACE
O
TOP OF VAULT
TOP OF
OVERFLOW EL=299.00-fir
DESIGN EL=299.00
0
EL=358.0
EL=358.VAULT 0
4• ELBOW
ELEV=298.2
°
U
WATER SURFACE
WATER SURFACE
ORIFICELu OIA=1.00'
Q
OESICN EL =358.4
DESIGN EL=358.4
J
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MODULAR CONC.
Z
BLOCK WALL
<
CEOFOAM BLOCKS
EPS46 OR EQUAL
BW; 306.24,
0
FINISHED GRADE
24'0 SOLID LOCKING LIO
24"0 SOLID LOCKING LIO-
W/ FRAME (TYP)
W/ FRAME (TYP)
(MARKED DRAIN}'-
`EXISTING GRADE
(MARKED GRAIN)
RIM=304.00
CD
TOP OF VAULT _
r
EL=300.5
-4• PERF. PVC,
04" PERF. PVC!
.....
W
- -
- -
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0.5' MIN.
=
U
-100-YEAR WATER SURFACE
B,
FREE80AR0
OESICN EL=299.00
LIVE STORACE
20.0'
20.0,
WATER QUALITY
OESICN EL=291.00
SEDIMENT STORACE
4.0'
OESICN EL=287.00
DEAD STORAGE
5.0%
y
INV=286.25
IN
1' MIN. SEDIMENT STORAGE
'5
INV=2
DETENTION VAULT SECTION (B-B)
REMOVABLE WATER-
TIGHT COUPLING
12" MAX 6'
PLATE WITH ORIFICE
OIA=1.00'
4" ELBOW DETAIL
PIPE SUPPORTS (2 MIN):-
3• X .090• ALUMINUM 1'-0•
W/ %- STAINLESS BOLTS MIN.
12' OUTLET PIPE
5'x10' GRATED LOCKING
REMOVABLE ACCESS PANEL
(MARKED GRAIN)
RIM=302.00
Souo
PIPE SUPPORTS (2 MIN):-"�-
3• X .090" ALUMINUM
8' SHEAR GATE W/ %- STAINLESS BOLTS MIN.
till_-
IE=295.65 ,,,, 12" MIN z
0
N
J
RESTRICTOR PLATE WITH e.
ORIFICE ELEV=293.65
DRILL A 1.25• HOLE IN
PLATE WELDED TO FIANCE
OR DRILLED TO CAP .a
FLOW RESTRICTOR TEE DETAIL
NTS
SCALE: 1" - 5'
ASPHALT SERVICE DRIVEWAY
CRASSCRETE SERVICE DRIVEWAY
CEOFOAM BLOCKS
EXISTINC GRADE
EPS46 OR EQUAL
24"0 SOLID LOCKING UO
FINISHED GRADE
W/ FRAME (TYP)
TRIM OR STEPPINC TOP ROW
(MARKED GRAIN)
24"0 SOLID LOCKINC UO
OF CEOFOAM BLOCKS TO _ - --
_-----
FINISHED CRADE
W/ FRAME (TYP)
MATCHFINISHED-GRADE-
(MARKED ORAIN)
5'x10' CRATED LOCKING
________-SLOPE_
RIM=304.00 --"
REMOVABLE ACCESS PANEL TOP OF VAULT
__--'--
-
MAX. DEPTH FROM
RIM=302-00 F1.�.,3Q0,5---- -----------_
_ _ _ _ _
-
_ - _ _
...._.
FINISHED CRADE
__----
-
_.
-
TO VAULT SHALL
- "' "-
-
BE 20 FEET AT
_
-
ACCESS POINTS
----____--._--
---'- 1Y FLOW RESTRICTOR TEE._--
_�--�
_._ _...
SEE DETAIL THIS SHEET
sow
34LF 12' LCPE TO CB #14
EL=298.2
FREE80AR0
(HICH FLOW BYPASS)
ORIFICE OIA.=1.00• 100-YEAR WATER SURFACE
_
8• SHEAR GATE OESICN EL=299.00
-CIE =295.6
FlCE EL=293.65
-
LIVE STORAGE
5'x7' OPENING
1Y FLOW RESTRICTOR TEE -.-----.,WATER
ORIFICE OIA.=1.25'
QUALITY
5'
W/ SOLID TOP
8' SHEAR GATE J OESICN EL.=291.00
/
-
7'
_
SEDIMENT STORAGE
4.0'
289.00
ORIFICE OIA.=0.68• OESICN EL=287.00
-
DEAD STORACE
27LF 12• LCPE
2'
LCPE
TO STORMFILTER
1' MIN. SEOIMENT STORACE
FROM C8
FROM C8 #1
MANHOLE
_.1.675
FRAME &LADDER OR
STEPS OFFSET. SEE
NOTE 8.
To0-YEAR WATER SURFACE
DESIGN EL=299.00
8• SHEAR CATE
_1 27" 0IJTLL7 PIPE
WATER QUALITY
DESIGN EL=291.00
IE=291.00
RESTRICTOR PLATE WITH e.
ORIFICE ELEV=290.00
DRILL A 0.6B' HOLE IN
PLATE WELDED TO FIANCE
OR ORILLEO TO CAP •a
e
e ,
a
FLOW RESTRICTOR TEE DETAIL
\INV.L285.00 Qu M y- UC 1 CIV I IVIV VAUL_ 1 SCC.: 1 IVIV ILA -A)
SCALE- 1' = 5'
r Pacific� r�rJ _ �. « .+ 1•=20. CITY OF
RENTON
�, q 1 J. HOPPER
Design, I ±� ss�pslsiE �� 2 SECOND ROUND CITY REVIEW COMMENTS IF 4 JH - E yApylyy
II F NAL 1 FIRST ROUND CITY REVIEW COMMENTS AL 2 1 JH o� a�� DATUM planning/building/Public Works Dept.
1 rCivil Lnglneerlr�g 1 4 /i/1 J. HOPPER . u ac wo
Planning ConsuJtanss NO. REVISION BY DATE APPR
NTS
R-391011
APPROVED FOR CONSTRUCTION
SUBJECT TO ERRORS AND OMISSIONS
BY:
DATE:
BY-
DATE:
BY-
DATE:
BY-
DATE:
GRANT PLACE TOWNHOMES
VAULT PLAN
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Planning Csnsvl_arris
OUTLET
SUMP
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OUTLET
TYID_MAN
SESLABAC ESS
\Tj
CDVERDETAIL
PLAN VIEW
STANDARD OUTLET RISER
FLDWMT: 42A
CONiRACTORTDGRGUTTO RIM=300.56
FINISHED GRADE
GRADE
RINGIRISERS
FLOATABLES
STDRMFILTER
CARTRIDGE
BAFFLE
INSIDE
INLET PIPE
HYDRAULIC ORDP
(H)INLET INV.
TO DUR.ET INV.
FLOW KR —_
Or,%Qp M. HOpAF
A
_NAILTE
HOPE DUTLET RISER
SECTION A -A
StarmFilter�
12' LCPE
INV. 2BB.57
STORMFILTER DESIGN NOTES
STDRMFILTER TREATMENTCAPACITY IS A FUNCTION OF THE CARTRIDGE SELECTION AND THE NUMBER OF CARTRIDGES. THE STANDARD MANHDLE
STYLE IS SHOWN WRH THE MAXIMUM NUMBER OF CARTRIDGES VI VOLUME SYSTEM IS ALSO AVAILABLE WITH MAXIMUM T CARTRIDGES.
072' MANHOLE STDRMFILTER PEAK HYDRAULIC CAPACITY IS 1.5 CFS. IF THE STIE CONDmDNS EXCEED 15 CFS AN UPSTREAM BYPASS STRUCTURE IS
REQUIRED,
CARTRIDGESELECTION
CARTRIDGE HEIGHT I 2T 16' LOW DROP
RECOMMENDED HYDRAULIC DROP(H) 3D5' 23' 1A.
SPECIFIC FLOW RATE PMS 2 gpmlR' l gp— 1 2 S,m 1 dind"' 2 SIP— 19PmM'
CARTRIDGE FLOW RATE(9Pm) -B 1125 15 TS 10 5
SITE SPECIFIC
DATA REQUIREMENTS
STRUCTURE ID
SF#1
WATER DUALITY FLOW RATE cfs
B092
PEAK FLOW RATE cFs
0.092
RETURNPERIDDDFPEAKFLOW
2
#DFCARTRIDGESREQUIRED
3
CARTRIDGE FLOW RATE
175GMP
MEDIA TYPE CEF, PERLFIE_ Z , GAC, PHS
I CSF
PIPE WTA:
I.E. 1 MATFRA. DIAMETER
INLET PIPE#1
290.87 LCPE
12'
INLET PIPE#2
WA I WA
WA
OUTLET PIPE
26B.S/ LCPE
12'
RIM ELEVATION
3mm
ANT4FLDTATION BALLAST WIDTH
6'
HEIGHT
2'
NOTESISPECIAL REQUIREMENTS:
' PER ENGINEER OF RECORD
GENERAL NOTES
1. CONTECH TO PROVIDE ALL MATER UNLESS NOTED OTHERWISE.
2. DIMENSIONS MARKED WRH () ARE REFERENCE DIMENSIONS. ACTUAL DIMENSIONS MAY VARY.
3. FOR SITE SPECIFIC DRAWINGS WITH DETAILED VAULT DIMENSIONS AND WEIGHTS, PLEASE CDNTACTYOUR CONTECH ENGINEERED SOLUTIONS
LLC REPRESENTATIVE. w+.w,�.=m
4. STORMFILTER WATER QUALITY STRUC E SHALL BE IN ACCORDANCE WTTH ALL DESIGN DATA AND INFDRMATIDN CONTAINED IN THIS
DRAWING.
5. STRU RESHALLMEETAASHTDHS2BLOADRATING,ASSUMINGEARTHCOVEROFT-6ANDGRDUNDWATERELEVATIONAT,DRBELDW,THE
OUTLET PIPEINVENTELEVATIDN. ENGINEEROFRECDRDTOCONFIRMACRIALGRDUNDWATERELEVATION. CASTINGSSHALLMEETAASHTD
M33B AND BE CAST WITH THE CONTECH LOGO.
6. FILTER CARTRIDGES SHALL BE MEDIA-FILLED_PASSIVE. SIPHON ACTUATED, RADIAL FLOW, AND SELF CLEANING. RADIALMEDIADEPTHSHALL
BE 7-INCHES. FILTER MEDIA CDNTACTTIME SHALL BE AT LEAST 39 SECDNDS.
T. SPECIFIC FLDWRATE IS EOUALTD THE FILTERTREATMENTCAPACITY(gpm) DIVIDED BYTHE FILTERCONTACTSUREACEAREA(a t).
INSTALLATION NOTES
i. ANYSUBAASE,BACK lL DEPTH,AND/DRANTFFLOTATIDNPRDVISIONSAREST PECIFICDESIGNCONSIDE nONSANDSHALLBE
SPECIFIED SY ENGINEER DF RECORD.
2. CONTRACTDRTO PROVIDE EQUIPMENT WITH SUFFICIENT LIFTING AND REACH CAPACITY TO LIFT AND SETTHE STORMFILTER STRUCTURE
(LIFTING CLUTCHES PROVIDED).
3.CNTRACTORTDINSTALLJOINTSEALANTBETWEENALLSTRUMN SECnONSANDASSEMBLESTRIJCTURE.
4. CDNTRACTORTDPRDVIDE,INSTALL,ANDGROUTINLETPIPE(S).
5. CDNTRACTORTO PRDVIDEAND INSTALL CONNECTOR TO THE OUTLET RISER STUB. STDRMFILTEREQIJIPPEDWITHADUALDIAMFTERHDPE
OUTLET STUB AND SAND COLLAR. IF OUTLET PIPE IS LARGER THAN B INCHES, CONTRACTOR TO REMDVE THE B INCH OURET STUB AT MDLDED
IN CUT LINE. COUPLING BY FERNCO OR EQUAL AND PROVIDED BY CONTRACTDR
6 CONTRACTOR TO TAKE APPROPRIATE MEASURES TO PROTECT CARTRIDGES FROM CONSTRUCTION -RELATED EROSION RUNOFF.
10- CITY OF cRFFrL 1'-20• B�,B9,1## �� >,-
R EN TO N
2 SECOND ROUND qTY REVIEW COMMENTS JF 4"APPR
E MMSIWL DATUM
1 MRST ROUND qTY REVIEW COMMENTS AL 2 Planning/Building/Public Works Dopt.
N0. REVISION 8Y DAT� 'r"'°f°1°'1°1f
R-391012
APPROVED FOR CONSTRUCTION
SUBJECT TO ERRORS AND OMISSIONS
BY:
DATE: .
BY:
DATE: .
BY:
DATE: .
BY:
DATE: .
GRANT PLACE TOWNHOMES
STORMALTER MANHOLE DETAILS
LO
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V. Conveyance System Analysis and Design
Conveyance system is designed per section 1.2.4.1 of 2009 City of Renton Surface Water
Design Manual Amendment to convey the 25-year developed peak flow with minimum 6
inches of free board and check for overflow for developed 100-year peak flow and shall
not cause downstream property damage in case overflow happens in 100-year storm
event.
Use rational method to calculate the 25 year and 100 year 24 hour peaks
QR=C*IR*A
IR=PR*iR
PR = 3.40 inch for 25 year storm
= 3.90 inch for 100 year storm
iR=aR*TCA(-bR)
Tc = Time of concentration = 6.3 minutes for small areas
aR
bR
iR for Tc = 6.3 minutes
IR for Tc = 6.3 minutes
25 year
2.66
0.65
0.804
2.734
100 year
2.61
0.63
0.819
3.194
Onsite storm network:
The onsite storm can be divided into three pipe networks. King County backwater method
is used to verify the capacity of the proposed conveyance systems.
Network #1 collects and conveys runoff from upstream tributary area east of the site, roof
and sidewalks of the two east buildings, pavements of the east and north public alleys
and landscape areas north of these two alleys.
Total drainage area = 0.886 acres.
Total impervious area = 0.482acres (C = 0.9)
Total pervious area = 0.404 acres (till grass, C = 0.25)
Q25y=C*IR*A=(0.90*0.482+0.25*0.404)*2.734=1.46cfs
Q1 00y = C * IR * A = (0.90 * 0.482 + 0.25 * 0.404) * 3.194 = 1.71 cfs
BACKWATER COMPUTER PROGRAM FOR PIPES
Pipe data from file:Nl.bwp
Surcharge condition at intermediate junctions
Tailwater Elevation:299. feet
Discharge Range:1.46 to 1.71 Step of 0.25 [cfs]
Overflow Elevation:355. feet
Weir:NONE
Upstream Velocity:l. feet/sec
PIPE NO. 1: 24 LF - 12"CP @ 47.92% OUTLET: 289.00 INLET: 300.50 INTYP: 5
JUNC NO. 1: OVERFLOW -EL: 303.50 BEND: 90 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.13
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
***********************************************************************************
Q25y 1.46 0.53 301.03 * 0.012 0.52 0.16 10.00 10.00 0.52 ***** 0.53
Q100 1.71 0.61 301.11 * 0.012 0.56 0.18 10.00 10.00 0.56 ***** 0.61
At CB#8 For 25-year peak 303.50 - 301.03 = 2.47 > 0.5, o.k.
For 100-year peak 303.50 - 301.11 = 2.39 > 0.0, o.k.
PIPE NO. 2: 82 LF - 1211CP @ 14.67% OUTLET: 300.50 INLET: 312.53 INTYP: 5
SUNC NO. 2: OVERFLOW -EL: 315.53 BEND: 0 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.14
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
***********************************************************************************
Q25y 1.29 0.59 313.12 * 0.012 0.49 0.20 0.53 0.53 0.49 ***** 0.59
Q100 1.51 0.65 313.18 * 0.012 0.53 0.22 0.61 0.61 0.53 ***** 0.65
At CB#9 For 25-year peak 315.53 - 313.12 = 2.41 > 0.5, o.k.
For 100-year peak 315.53 - 313.18 = 2.35 > 0.0, o.k.
PIPE NO. 3: 87 LF - 1211CP @ 4.05% OUTLET: 312.53 INLET: 316.05 INTYP: 5
SUNC NO. 3: OVERFLOW -EL: 319.05 BEND: 0 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.17
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
***********************************************************************************
Q25y 1.13 0.60 316.65 * 0.012 0.45 0.26 0.59 0.59 0.45 ***** 0.60
Q100 1.33 0.66 316.71 * 0.012 0.49 0.28 0.65 0.65 0.49 ***** 0.66
At CB#10 For 25-year peak 319.05 - 316.65 = 2.40 > 0.5, o.k.
For 100-year peak 319.05 - 316.71 = 2.34 > 0.0, o.k.
PIPE NO. 4: 104 LF - 12"CP @ 7.64% OUTLET: 316.05 INLET: 324.00 INTYP: 5
SUNC NO. 4: OVERFLOW -EL: 327.00 BEND: 0 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.20
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
***********************************************************************************
Q25y 0.97 0.53 324.53 * 0.012 0.42 0.21 0.60 0.60 0.42 ***** 0.53
Q100 1.13 0.58 324.58 * 0.012 0.45 0.23 0.66 0.66 0.45 ***** 0.58
At CB#ll For 25-year peak 327.00 - 324.53 = 2.47 > 0.5, o.k.
For 100-year peak 327.00 - 324.58 = 2.42 > 0.0, o.k.
PIPE NO. 5: 106 LF - 12"CP @ 7.63% OUTLET: 324.00 INLET: 332.09 INTYP: 5
SUNC NO. 5: OVERFLOW -EL: 335.09 BEND: 30 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.25
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
***********************************************************************************
Q25y 0.81 0.48 332.57 * 0.012 0.38 0.19 0.53 0.53 0.38 ***** 0.48
Q100 0.95 0.53 332.62 * 0.012 0.41 0.21 0.58 0.58 0.41 ***** 0.53
At CB#12 For 25-year peak 335.09 - 332.57 = 2.52 > 0.5, o.k.
For 100-year peak 335.09 - 332.62 = 2.47 > 0.0, o.k.
PIPE NO. 6: 44 LF - 1211CP @ 11.05% OUTLET: 332.09 INLET: 336.95 INTYP: 5
SUNC NO. 6: OVERFLOW -EL: 340.61 BEND: 30 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.33
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
*******************************************************************************
Q25y 0.65 0.41 337.36 * 0.012 0.34 0.16 0.48 0.48 0.34 ***** 0.41
Q100 0.76 0.45 337.40 * 0.012 0.37 0.17 0.53 0.53 0.37 ***** 0.45
At CB#13 For 25-year peak 340.61 - 337.36 = 3.25 > 0.5, o.k.
For 100-year peak 340.61 - 337.40 = 3.21 > 0.0, o.k.
PIPE NO. 7: 52 LF - 1211CP @ 8.94% OUTLET: 336.95 INLET: 341.60 INTYP: 5
SUNC NO. 7: OVERFLOW -EL: 344.33 BEND: 70 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.50
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
***********************************************************************************
Q25y 0.49 0.35 341.95 * 0.012 0.29 0.14 0.41 0.41 0.29 ***** 0.35
Q100 0.57 0.39 341.99 * 0.012 0.32 0.16 0.45 0.45 0.32 ***** 0.39
At CB#6 For 25-year peak 344.33 - 341.95 = 2.38 > 0.5, o.k.
For 100-year peak 344.33 - 341.99 = 2.34 > 0.0, o.k.
PIPE NO. 8: 111 LF - 12"CP @ 6.56% OUTLET: 341.60 INLET: 348.88 INTYP: 5
41
JUNC NO. 8: OVERFLOW -EL: 351.60 BEND: 0 DEG DIA/WIDTH: 2.0 Q-RATIO: 1.00
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
***********************************************************************************
Q25y 0.32 0.29 349.17 * 0.012 0.24 0.13 0.35 0.35 0.24 ***** 0.29
Q100 0.38 0.31 349.19 * 0.012 0.26 0.14 0.39 0.39 0.26 ***** 0.31
At CB# 7 For 25-year peak 351.60 - 349.17 = 2.43 > 0.5, o.k.
For 100-year peak 351.60 - 349.19 = 2.41 > 0.0, o.k.
PIPE NO. 9: 15 LF - 1211CP @ 7.47% OUTLET: 348.88 INLET: 350.00 INTYP: 5
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
***********************************************************************************
Q25y 0.16 0.17 350.17 * 0.012 0.17 0.09 0.29 0.29 0.17 ***** 0.17
Q100 0.19 0.19 350.19 * 0.012 0.18 0.10 0.31 0.31 0.18 ***** 0.19
At CB# 18 For 25-year peak 355.00 - 350.17 = 4.83 > 0.5, o.k.
For 100-year peak 355.00 - 350.19 = 4.81 > 0.0, o.k.
All catch basins of network #1 have more than 6 inches of free board for 25-year storm
peak and no overflow happen for 100-year storm peak.
Network #2 collets and conveys runoff from the pavement of the south public alley,
pervious area from Tract C and landscape areas east and south of the south public alley.
Total drainage area = 0.474 acres.
Total impervious area = 0.284 acres (C = 0.9)
Total pervious area = 0.190 acres (till grass, C = 0.25)
Q25y = C * IR * A = (0.90 * 0.284 + 0.25 * 0. 190) * 2.734 = 0.83 cfs
Q1 00y = C * IR * A = (0.90 * 0.284 + 0.25 * 0. 190) * 3.194 = 0.97 cfs
BACKWATER COMPUTER PROGRAM FOR PIPES
Pipe data from file:N2.bwp
Surcharge condition at intermediate junctions
Tailwater Elevation:299. feet
Discharge Range:0.83 to 0.97 Step of 0.14 [cfs]
Overflow Elevation:333.6 feet
Weir:NONE
Upstream Velocity:l. feet/sec
PIPE NO. 1: 34 LF - 1211CP @ 39.06% OUTLET: 289.00 INLET: 302.28 INTYP: 5
JUNC NO. 1: OVERFLOW -EL: 305.28 BEND: 90 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.25
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
***********************************************************************************
Q25y 0.83 0.39 302.67 * 0.012 0.39 0.13 10.00 10.00 0.39 ***** 0.34
Q100 0.97 0.42 302.70 * 0.012 0.42 0.14 10.00 10.00 0.42 ***** 0.40
At CB#1 For 25-year peak 305.28 - 302.67 = 2.61 > 0.5, o.k.
For 100-year peak 305.28 - 302.70 = 2.58 > 0.0, o.k
PIPE NO. 2: 60 LF - 1211CP @ 14.58% OUTLET: 302.28 INLET: 311.03 INTYP: 5
JUNC NO. 2: OVERFLOW -EL: 314.03 BEND: 10 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.33
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
***********************************************************************************
Q25 0.66 0.39 311.42 * 0.012 0.34 0.15 0.39 0.39 0.34 ***** 0.39
Q100 0.78 0.43 311.46 * 0.012 0.37 0.16 0.42 0.42 0.37 ***** 0.43
At CB#2 For 25-year peak 314.03 - 311.42 = 2.61 > 0.5, o.k.
For 100-year peak 314.03 - 311.46 = 2.57 > 0.0, o.k
PIPE NO. 3: 90 LF - 12"CP @ 4.00% OUTLET: 311.03 INLET: 314.63 INTYP: 5
42
JUNC NO. 3: OVERFLOW -EL: 317.63 BEND: 0 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.50
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
***********************************************************************************
Q25 0.50 0.38 315.01 * 0.012 0.30 0.18 0.39 0.39 0.30 ***** 0.38
Q100 0.58 0.42 315.05 * 0.012 0.32 0.19 0.43 0.43 0.32 ***** 0.42
At CB#3 For 25-year peak 317.63 - 315.01 = 2.62 > 0.5, o.k.
For 100-year peak 317.63 - 315.05 = 2.58 > 0.0, o.k
PIPE NO. 4: 99 LF - 1211CP @ 7.34% OUTLET: 314.63 INLET: 321.90 INTYP: 5
JUNC NO. 4: OVERFLOW -EL: 324.90 BEND: 0 DEG DIA/WIDTH: 2.0 Q-RATIO: 1.00
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
***********************************************************************************
Q25 0.33 0.29 322.19 * 0.012 0.24 0.13 0.38 0.38 0.24 ***** 0.29
Q100 0.39 0.31 322.21 * 0.012 0.26 0.14 0.42 0.42 0.26 ***** 0.31
At CB#4 For 25-year peak 324.90 - 322.19 = 2.71 > 0.5, o.k.
For 100-year peak 324.90 - 322.21 = 2.69 > 0.0, o.k
PIPE NO. 5: 108 LF - 12"CP @ 8.05% OUTLET: 321.90 INLET: 330.59 INTYP: 5
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
***********************************************************************************
Q25y 0.17 0.17 330.76 * 0.012 0.17 0.09 0.29 0.29 0.17 ***** 0.17
Q100 0.19 0.19 330.78 * 0.012 0.19 0.10 0.31 0.31 0.19 ***** 0.19
At CB#5 For 25-year peak 333.60 - 330.76 = 2.84 > 0.5, o.k.
For 100-year peak 333.60 - 330.78 = 2.82 > 0.0, o.k
All catch basins of network #2 have more than 6 inches of free board for 25-year storm
peak and no overflow happen for 100-year storm peak.
Network #3 collets and conveys runoff from the roof and sidewalk of the six central
buildings and landscape areas in the central area.
Total drainage area = 0.763 acres.
Total impervious area = 0.477 acres (C = 0.9)
Total pervious area = 0.286 acres (till grass, C = 0.25)
Q25y=C*IR*A=(0.90*0.477+0.25*0.286)*2.734=1.37cfs
Q100y=C*IR*A=(0.90*0.477+0.25*0.286)*3.194=1.60cfs
BACKWATER COMPUTER PROGRAM FOR PIPES
Pipe data from file:N3.bwp
Surcharge condition at intermediate junctions
Tailwater Elevation:299. feet
Discharge Range:1.37 to 1.6 Step of 0.23 [cfs]
Overflow Elevation:329.9 feet
Weir:NONE
Upstream Velocity:l. feet/sec
PIPE NO. 1: 31 LF - 1211CP @ 75.48% OUTLET: 289.00 INLET: 312.40 INTYP: 5
JUNC NO. 1: OVERFLOW -EL: 315.48 BEND: 30 DEG DIA/WIDTH: 2.0 Q-RATIO: 0.50
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
***********************************************************************************
Q25y 1.37 0.50 312.90 * 0.012 0.50 0.14 10.00 10.00 0.50 ***** 0.33
Q100 1.60 0.54 312.94 * 0.012 0.54 0.15 10.00 10.00 0.54 ***** 0.40
At CB#15 For 25-year peak 315.48 - 312.90 = 2.58 > 0.5, o.k.
For 100-year peak 315.48 - 312.94 = 2.54 > 0.0, o.k
43
PIPE NO. 2: 121 LF - 12"CP @ 5.54% OUTLET: 312.40 INLET: 319.10 INTYP: 5
JUNC NO. 2: OVERFLOW -EL: 322.10 BEND: 0 DEG DIA/WIDTH: 2.0 Q-RATIO: 1.00
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
***********************************************************************************
Q25y 0.91 0.53 319.63 * 0.012 0.41 0.22 0.50 0.50 0.41 ***** 0.53
Q100 1.07 0.59 319.69 * 0.012 0.44 0.24 0.54 0.54 0.44 ***** 0.59
At CB#16 For 25-year peak 322.10 - 319.63 = 2.47 > 0.5, o.k.
For 100-year peak 322.10 - 319.69 = 2.41 > 0.0, o.k
PIPE NO. 3: 103 LF - 12"CP @ 7.57% OUTLET: 319.10 INLET: 326.90 INTYP: 5
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
***********************************************************************************
Q25y 0.46 0.33 327.23 * 0.012 0.28 0.15 0.53 0.53 0.28 ***** 0.33
Q100 0.53 0.36 327.26 * 0.012 0.31 0.16 0.59 0.59 0.31 ***** 0.36
At CB#17 For 25-year peak 329.90 - 327.23 = 2.67 > 0.5, o.k.
For 100-year peak 329.90 - 327.26 = 2.64 > 0.0, o.k
All catch basins of network #3 have more than 6 inches of free board for 25-year storm
peak and no overflow happen for 100-year storm peak.
Network #4 (From 15" CMP culvert downstream existing CB SDMH#1 at Grant Avenue
South to onsite detention/wet vault outfall pipe upstream of CB#14):
The Grant Avenue South storm drainage network at the frontage of the site collects runoff
from 4 drainage sub -basins.
Sub -basin #1: The site (2.11 acres) plus the upstream tributary area east of the site (0.22
acres).
The 25-year and 100-year detention/wet vault release rates are:
Q25y = 0.127 cfs
Q100y = 0.258 cfs
Sub -basin #2: The Heritage Village Condo property south of the site (1.86 acres)
This development was built around 1988 using Level 1 Flow Control Standard. A 57LF
96" diameter detention tank was installed for flow control and the tank is still existing.
Assume the design was to match existing condition before 1979 which was a single family
condition (C = 0.35).
Q25y=C*IR*A=0.35*2.734*1.86=1.78cfs
Q100y=C*IR*A=0.35*3.194*1.86=2.08cfs
Sub -basin #3: The Puget Sound Energy property north of the site (tributary area 8.38
acres, C=0.2 for pasture)
Q25y=C* I R * A = 0.20 * 2.734 * 8.38 = 4.58 cfs
Q100y=C*IR*A=0.20*3.194*8.38=5.35cfs
Sub -basin #4: Grant Avenue South Right of way
Total area = 0.75 acres
44
Total impervious area = 0.55 acres (C=0.9)
Total pervious area = 0.20 acres (till grass, C = 0.25)
Q25y = C * IR * A = (0.55*0.9 + 0.20*0.25) * 2.734 = 1.49 cfs
Q100y = C * IR * A = (0.55*0.9 +0.20*0.25) * 3.194 = 1.74 cfs
The 25-year and 100-year peak flows at the 15" CMP culvert downstream of existing
catch basin SDMH#1 are:
Q25y=0.127+1.78+4.58+1.49=7.98cfs
Q100y=0.258+2.08+5.35+1.74=9.43cfs
BACKWATER COMPUTER PROGRAM FOR PIPES
Pipe data from file:OS.bwp
Surcharge condition at intermediate junctions
Tailwater Elevation:282.99 feet
Discharge Range:7.98 to 9.43 Step of 1.45 [cfs]
Overflow Elevation:302. feet
Weir:NONE
Upstream Velocity:l. feet/sec
PIPE NO. 1: 48 LF - 15"CMP @ 9.60% OUTLET: 281.99 INLET: 286.60 INTYP: 5
JUNC NO. 1: OVERFLOW -EL: 294.54 BEND: 0 DEG DIA/WIDTH: 4.0 Q-RATIO:35.55
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
***********************************************************************************
Q25y 7.98 2.46 289.06 * 0.024 1.12 0.80 1.00 1.00 1.12 ***** 2.46
Q100 9.43 3.13 289.73 * 0.024 1.17 0.91 1.00 1.00 1.17 ***** 3.13
At existing catch basin SDMH#[1 at Grant Avenue South
For 25-year peak 294.54 - 289.06 = 5.48 > 0.5, o.k.
For 100-year peak 294.54 - 289.73 = 4.81 > 0.0, o.k
PIPE NO. 2: 50 LF - 1211CP @ 2.32% OUTLET: 287.34 INLET: 288.50 INTYP: 5
JUNC NO. 2: OVERFLOW -EL: 296.27 BEND: 45 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.00
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
***********************************************************************************
Q25y 0.22 0.57 289.07 * 0.012 0.20 0.14 1.72 1.72 0.57 0.57 0.25
Q100 0.26 1.24 289.74 * 0.012 0.21 0.15 2.39 2.39 1.24 1.24 0.27
At new catch basin CB#[14
For 25-year peak 296.27 - 289.07 = 7.20 > 0.5, o.k.
For 100-year peak 296.27 - 289.74 = 6.53 > 0.0, o.k
PIPE NO. 3: 34 LF - 1211CP @ 7.35% OUTLET: 288.50 INLET: 291.00 INTYP: 5
Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI
************************************************************************************
Q25y 0.22 0.21 291.21 * 0.012 0.20 0.10 0.57 0.57 0.20 ***** 0.21
Q100 0.26 0.23 291.23 * 0.012 0.21 0.11 1.24 1.24 0.21 ***** 0.23
At northwest corner of new detention/wet vault
For 25-year peak 302.00 - 291.21 = 10.79 > 0.5, o.k.
For 100-year peak 302.00 - 291.23 = 10.77 > 0.0, o.k
All catch basins of network #4 have more than 6 inches of free board for 25-year storm
peak and no overflow happen for 100-year storm peak.
«1
/
CB #14
O
NOTES
CB-11
(HIGH FLOW BYPASS)
f
'� _
14LF 12" LCPE-
O
FOR NEW STORM DRAIN RIMS AND INVERTS
- -
MANHOLE
/
M
SEE PROFILE AND STRUCTURE TABLE ON
I
SFMH#1 WICSF CARTRIDGES
'
O
SHEET CD9
CB #8
82LF/12" LCPE
FOR EXISTING STORM DRAINAGE SYSTEM
I SDLF 3 LOPE
ALONG GRANT AVENUE AND OTHER OFFSITE
g - -
- "-
300 BW-304
STORM DRAINAGE SYSTEM SEE SHEET CD2
' M , \
(Z
® Bw _
w
" FOR STANDARD STORM DRAIN MATERIALS
S H-1
I'
AND DETAILS SEE CITY OF RENTON
\
j
STANDARD DETAIL PLANS
\
-
ALL ONSITE WALKWAYS TO BE POROUS
PAVEMENT, TOTAL 9,D31 SF. SEE SHEET
C14 FOR DETAIL OYP.) PUBLIC WATER EASEMENT
(FROM R.O.W. LINE TO 'fU CB #13
CB #9 87LF 12" LCPE CB #10 1D4LF 12" LCPE tD6LF 12"�LCPE
Bw-34o ,
- Ili �m_..e / BW=3t m BW--D-_---'- 23LF 6" m f
rHw s CALC89
CUT: 2,. DD CU YD
FILL, 2JZOO CU YD
NET: - 1DD CU YD [CUT]
54
ALL WALLS EXCEEDING 4 FEET IN HEIGHT SS.:.: ;;;. ` S ::: :� �` ��4b H I wl
l
15 'T2�' CPE
WILL REQUIRE SEPARATE BUILDING PERMITS. 1ST F� I15T FF 1ST rF= ItsT FF=1 tsr FF-IR
DETENTION VAULTS WILL REQUIRE SEPARATE INGRESS EGRESS AND LTIY+ (QEASEMENT TO BE OBTAINS i asDO ass 13s�.0 3sasw BUILDING PERMIT. FROM PSE '` I 1 T - � 2NJ8FF NO FF- ND - N6 .0 NO FF-
L STORM DRAINS IN ALLEY TO BE PUBLI0. 1ST FF-1ST FF- 1ST IT= 1ST FF-' 1ST FF- IST FF= 1ST FF- 1ST FF= 'iST FF= 1ST FF=1ST FF= 1ST FF= 3350 3585 12360.0 123615 �363.0 z3SEE SHEET CD3 FOR CITY EASEMENT ON 34U 12" LCPE '•"'`F' 3tD 1I 317.5 1 3175 1 "9-D 324.0 1325.5 325.5 3320 1333.5 I 333.5 I2N0 FF= :: LCPE
345.0 O TRACT A FOR VAULT MAINTENANCE, SIGNS1D' WIDE TYPE Ci AND ONE WAY ARROWS ON PAVEMENT C#15DRIVEWAY PER RENTON o+DD z ALONG PUBLIC ALLEY. STD PLAN 1D4 `C tu " -
FLOW CONTROL BMPS USED \ , r �_I 1sT FF= 11sr FF=I s FF I BW-352
� IX7S11NG ¢ R.O.W. � wXp 6 I
w ONSITE PERVIOUS CONCRETE SIDEWALK=9,D31 SF. otw3oe - -` t3 F
GRASSCRETE VAULT ACCESS DRIVEWAY=1,973 SF. CB#17 50.0 3sts 353FF 3sa.5 I
QU \ 121 12" (PR ATE) 1D3LF 1 LCPE PRNA I I 2No 12ND .0 1zND..5 1236 .0 12ND .5
TREE PRESERVATION (TRACT C) = 2,595 SF. COMBINED PUBLIC DETEMION/WET 1 g" I( �) 1ST F5- 358. 360.0 361.5 363A 36e,5
VAULT .t1. 31LF 12" LGIPE RATE) _ 1ST FF_ 1ST FF- 1ST fF 1ST FF= 1ST FF= I iS3z.0 11ST IJ 333.5 1 I I I
_ 1 O• \' 1ST F- ItST FF-1 . `F= 11ST FF-I 1ST FF= - I - I 1
p CONSERVATION FLOW CONTROL e' DEEP LIVE STORAGE \ 6� 3 322.0 323.5 323.5 325.0 3:50.5 332.0 332.0 2ND FF= Y
2B,BDDCF TOTAL PROVIDED ` 3145 316.0 316.0 376.0 317.5.' 343.5
F_ FACILITY 2B,767CF REQUIRED S"D I c INSTALL OD CO
4' DEEP DEAD STORAGE \ �I� EAST P EG O
< PUBLIC COMBINED DETENTION/WET VAULT. 13,6DDCF TOTAL PROVIDED Do
NC
:; N. ? _ P
7,26DCF REQUIRED : \ -'; g=1+�-i� J "SHEETS 13 FOf� O
CD ENHANCED BASIC WO FACILITY EX. STREET LIGHT TO N�;. ' SS SS S .::. S - - _ - -- - - - -- - DETAI I ' L�j
S - ew-347
REMAIN ,. ... :. ...... .- -
- - - _�.
TREATMENT TRAIN OF PUBLIC COMBINED �a / '_. CB #S - - Q
DETENTION/WET VAULT AND STORMFILTER 2D' WIDE TYPE C18 \ - CB #2 BWm338 BW-338
MANHOLE W/CSF CARTRIDGES. DRIVEWAY PER RENTON \OMH-a CB #3 CB #4
tD+4J ''�. 1D' WIDE TYPE Cl 99LF 1Y LCPE 1D8LF 12" LCPE 23LF 6" LCPE I J
STD PLAN 1D4.4, ,-"-= DRIVEWAY PER RENTON 9DLF 12" LCPE INSTALL WOOD: FENCE
SIDEWALK AT DRIVEWAY STD PLAN 1D4 R.O.W. LINE ALONG SOUTH PROPE 1
CROSSING SHOULD NOT 6DLF 12" LCPE UNE, SEE SHEET C13
CO BE DEPRESSED AT cg a \ n1ET111lORK /,c2 FOR OETAIL
O LOCATIONS WHERE // - \ 34LF 12" LCPE NETWORK V U FC T� 7t
I- LANDSCAPING IS MORE DOS77NG CURB ce_asDM o1A CB #1 - 30 0 110 20 30 60
w THAN 5 FEET WIDE TOTAL AREA=0.474 AC.
w NETWORK#3 ,�
_ IMPERVIOUS AREA=0.284 AC.GROHICSCALE
°' TOTAL AREA=0.763 AC. PERVIOUS AREA=0.190 AC. S4LE11"-W'
6D' PUBLIC R.O.W. I IMPERVIOUS AREA=0.477 AC.
�, R.O. 31.5' PUBLIC 1/2 R.D.W. .5' 21' PUBLIC R.D.W. (TILL GRASS) NETWORK#1
30' 3D' y I 5' SIDEWALK PERVIOUS AREA=0.286 AC. 3 3
(TILL GRASS) 2D' TRAVELLED WAY o o TOTAL AREA=0.866 AC. o
1.5' R.O.W. DEDICATION I I 5' PRIVATE SIDE
35.87't TRAVELLED WAY (VARIES) 8' w i1w �i 2D' TRAVELLED WAY I� IMPERVIOUS AREA-0.482 AC.
EXISTING ANDSCAPE cn I v1
18 0 SID WALK CONCRETE ' o I 7D' 1D' 0 1D' L 1D' I. SIDEWALK CDN - :O
SIDEWALK EXISTING 10' L 1D' L SIDEWALK K CONCRETE _ _
CURB (TYPICAL) EXISTING 6" 27 1.5 4; I II ;';;PERVIOUS AREA=0.404 AC.
PAVEMENT
CENTER LINE DF I I 0- 1
�IPAVE NT D.6't CURB 3I I3 87 CURB 8% exI I lex 87 I CURB 8%
0 `({11\ `\\ o MAX. I 27 2% 11.5 MAX. AXI 27 2y, (MA MAX. I 2% I 2% 11.5 MAX. (TILL GRASS)
I EXISTING `EXISTING `EXISTING dI Ia 2" A.0 2" A C 0 4' 2" A.0
ppp
POWER STORM GAS i (o WEARING COURSE WEARING COURSE �I I I WEAR NG COURSE a WEARING COURSE
Of I
w a 2" AI 2" A.0 10" WATER MAIN 1,�. --I. �11". 2" A'C 12" STORM SEWER 5' iD' T 2 A.0
x
EXISTING EXISTING I,I�-*� -III' BEARING COURSE 10" WATER MAN g' 5' 5' 8' BEARING COURSE 6.7't 3.3't BEARING COURSE BEARING COURSE
CABLE WATER 7D" WATER MAIN 5.4't 4.3't
6" CRUSHED ROCK 12" STORM SE R 6" CRUSHED ROCK 6" CRUSHED RDCK 6" CRUSHED ROCK
NDM- EXISTING UTIUTY DEPTHS ARE ASSUMED SUBGRADE SUBGRADE SUBGRADE B" SANITARY SEWER SUBGRADE
GRANT AVENUE 12" STORM SEWER 8" SANITARY SEWER 12" STORM SEWER 10" WATER MAIN
CROSS SECTION A NDM, PAVEMENT THICKNESS PER CDR 4-6-OBO.F.5 N= PAVEMENT THICKNESS PER CDR 4-6-060.E.5 NOTE; PAVEMENT THICKNESS PER CDR 4-6-060.F.5 NOTE; PAVEMENT THICKNESS PER CDR 4-6-060.F.5
FINAL PAVEMENT THICKNESSES PENDING FINAL PAVEMENT THICKNESSES PENDING FINAL PAVEMENT THICKNESSES PENDING FINAL PAVEMENT THICKNESSES PENDING
SCALT-V GEOTECHNICAL ENGINEER'S REPORT GEOTECHNICAL ENGINEER'S REPORT GEOTECHNICAL ENGINEER'S REPORT GEOTECHNICAL ENGINEER'S REPORT
10' GRANT CIRCLE S.E. (PUBLIC ALLEY) PUBLIC ALLEY GRANT CIRCLE (PUBLIC ALLEY) GRANT CIRCLE (PUBLIC ALLEY)
TEMPORARY CROSS SECTION C CROSS SECTION D CROSS SECTION E CROSS SECTION F
CONSTRUCTION EASEMENT SCALE; r-V SCALE r-V SCALE r-V SCALE: r-V
FROM PSE 5' 20.5' PUBLIC R.D.W. 3'
10'
Z TEMPORARY
-'ILI
0' TRAVELLED WAY CONSTRUCTION
rl w EASEMENT
cn FROM PSE 22.35'
oz I z 5.83' 4' VARIES Z
Ak di I I z I 4' 15.5'
3
1 w I�
4' MAX. HIGH CURB
NEW ROCKERY 27 I ?3I w 0 B.D w R-391008
I ~ of lo.__..
SEE FOR DETAIL 2" A.0 SHT C14'NqX. o_I 0 3 3-- 'a APPROVED FOR CONSTRUCTION
WEARING COURSE gy, 1- a9 \ SUBJECT TO ERRORS AND OMISSIONS w 4' 4' MAX. HIGH _
2" A.0 I 1.57 MAX. MAX. 1.57 '__� 12" STORM SEWER BEARING COURSE NEW ROCKERY I 2
1D" WATER MAIN 5 10 7 SEE SHT C14 4' MAX. HIGH
6" CRUSHED ROCK NEW RDCKERIES 0
TE:
SUBGRADE FDR DETAIL I I SEE SHT C14 DATE:
NOPAVEMENT THICKNESS PER CDR 4-6-060.F.5 8" SANITARY SEWER 4" CONCRETE 4" CONCRETE FOR DETAIL
FINAL PAVEMENT THICKNESSES PENDING SIDEWALK SIDEWALK BY: DATE: z
GEOTECHNICAL ENGINEER'S REPORT
GRANT CIRCLE S.E. (PUBLIC ALLEY) BY. DATE.
CROSS SF_
CROSS SECTION B �QN M NOpA SCALE-
G CROSS�SEECpT10N H BY, DATE: U
w
SCALE r-V 0°i�pF Sy/ Q
3' �� �o� T. + "'"� "° e` GRANT PLACE TOWNHOMES 2016-12-2
ev,
aCHIC 1 d' t y ®m 1"=20, xania, wn i .n 4' CITY OF�, 4laMM HOI�FER `n RENTON o� E-
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VI. Special Reports and Studies
Special Reports related to this project:
• Geotechnical Report. Nelson Geotechnical Assocaites, Inc., June 10, 2005
• Traffic Report. Jake Traffic Engineering, Inc., January 21, 2014
• NPDES Permit. Washington Department of Ecology
46
GEOTECHNICAL ENGINEERING
EVALUATION
GRANT'S PLACE
RENTON, WASHINGTON
PREPARED FOR
TRIDOR, INC.
NEL,SoN GEoTECHNICAL
ASSOCIATES, INC.
GEOTECHNIGAL ENGINEERS & GEOLOGISTS
17311--135'h Avenue NE, A-500
Woodinville, WA 98072
(425) 486-1669 . (425) Fax 481-2510
June 10, 2005
Mr. Scott Wiklof
Tridor Inc.
P.O. Box 747
Bellevue, WA 98009
Geotechnical Engineering Evaluation
Grant's Place
Renton, Washington
NGA File No. 712005
Dear Mr. Wiklof:
Snohomish County (425) 337-1669
Wenatchee/Chelan (509) 784-2756
We are pleased to submit the attached report titled "Geotechnical Engineering Evaluation — Grant's Place
— Renton, Washington." This report summarizes the existing surface and subsurface conditions within the
site and provides general recommendations for the proposed site development. Our services were
completed in general accordance with the proposal signed by you on May 17, 2005.
The site is currently occupied by a single-family residence and several outbuildings with brush and
scattered trees within the western portion of the property. Development for this property is planned to
consist of the construction of multiple three-story townhornes with associated pavement and utilities.
Stormwater is to be managed on site via a detention system within the planned driveway access road. We
monitored the excavation of eight test pits in the planned development areas. Our explorations indicated
that the site is generally underlain by competent native glacial till deposits.
The site is located in an area that was historically mined for coal. We did not observe evidence of mining
operations such as mine shafts or tailings on this site. We also reviewed materials related to past coal
mining activities in the site vicinity at the Washington State Department of Natural Resources. Based on
our observations and the information we reviewed, it appears that mining operations were not specifically
located on this site.
We have concluded that the site is generally compatible with the planned development. We have
recommended that the new structures be founded on the native medium dense or better soil for bearing
capacity and settlement considerations. These soils should be encountered approximately one to two feet
below the existing ground surface, based on our explorations.
Minor to moderate amounts of groundwater were encountered within the upper soils in many of the test
pits which may impact construction if earthwork activities take place during the wetter times of the year.
Also, footing drains and other drainage systems should be incorporated into the design to control
groundwater. In the attached report, we have also included general recommendations for site grading and
drainage.
Geotechnical Engineering Evaluation
Grant's Place
Renton, Washington
June 10, 2005
NGA File No. 712005
Summary - Page 2
It has been a pleasure to provide service to you on this project. Please contact us if you have any
questions regarding this report or require further information.
Sincerely,
NELSON GEOTECHNICAL ASSOCIATES, INC.
\aleMO.Sbawish, PE
Principal
Three Copies Submitted
TABLE OF CONTENTS
INTRODUCTION..................................................................................•................................................... I
SCOPE...........................................................•............................................................................................. I
SITECONDITIONS.................................................................................................................................. 2
SurfaceConditions.................................................................................................................................... 2
SubsurfaceConditions.............................................................................................................................. 2
HydrologicConditions.............................................................................................................................. 3
SENSITIVE AREA EVALUATION...................................................................................................•..... 3
SeismicHazard......................................................................................................................................... 3
ErosionHazard.......................................................................................................................................... 4
CONCLUSIONS AND RECOMMENDATIONS.........................................:......................................... 4
General................. ..... .......... ..... ... .............................................................................................................. 4
Erosion Control Measures..................................................................................................................... 5
Temporaryand Permanent Slopes............................................................................................................ 5
SitePreparation and Grading....................................................................................................................
6
FoundationSupport .................................... ................................._............................................_........._..._..
7
StructuralFill............................................................................................................................................ 8
Slab-on-Grade.................................................................................................................... ..............
9
Pavements............................................................................................................................ .......
10
SiteDrainage...........................................................................................................................................
10
USEOF THIS REPORT.............................................................•............................................................11
LIST OF FIGURES
Figure 1 — Vicinity Map
Figure 2 — Site Plan
Figure 3 — Soil Classification Chart
Figures 4 and 5 — Test Pit Logs
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Grant's Place
Renton, Washington
INTRODUCTION
This report presents the results of our geotechnical engineering investigation and evaluation of the
planned Grant's Place development in Renton, Washington. The project site is located at 1600 Grant
Avenue South as shown on the Vicinity Map in Figure 1_ The purpose of this study is to explore and
characterize the site's surface and subsurface conditions and to provide geotechnical recommendations for
site development. For our use in preparing this report, we have been provided with a site plan titled
"Grant's Place," dated May 10, 2005, prepared by Kovach Architects.
Development on the property will consist of the construction of 39 three-story, wood -framed townhome
structures. A paved access driveway is planned for the middle of the property and will be accessed from
Grant Avenue South on the western side of the property. Stormwater handling is planned to consist of an
underground detention pipe or vault within the planned access road. The proposed site layout is shown
on the Site Plan in Figure 2.
SCOPE
The purpose of this study is to explore and characterize the site surface and subsurface conditions, and
provide general recommendations for site development. Specifically, our scope of services includes the
following:
1. Review existing soils, geologic, and coal mine maps of the area.
2. Explore the site subsurface soil and groundwater conditions with trackhoe-excavated test
pits. Trackhoe was subcontracted by NGA.
3. Provide recommendations for site grading and earthwork, including structural fill.
4. Provide recommendations for foundation support and slabs -on -grade subgrade.
5. Provide recommendations for stormwater infiltration or detention system installations as
needed.
6. Provide recommendations for site drainage and erosion control.
7. Provide recommendations for pavement subgrade preparation.
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Grant's Place
Renton, Washington
June 10, 2005
NGA File No. 712005
Page 2
8. Document the results of our explorations, findings, conclusions, and recommendations in
a written geotechnical engineering report.
SITE CONDITIONS
Surface Conditions
The site is an approximate 2.1-acre, trapezoidal -shaped lot measuring approximately 621feet and 541 feet
along the northern and southern property lines, respectively, and approximately 158 feet and 177 along
the eastern and western property lines, respectively. The site is bounded to the east and south by
residential properties, to the west by Grant Avenue South, and to the north by and undeveloped land.
A single-family residence with a maintained grass lawn, scattered trees, and several outbuildings occupy
the western portion of the property. The site is generally level with a slight gradient down to the west.
An old shed, blackberry bushes, and scattered trees occupy the eastern half of the property. A small
irrigation pond with a 3-foot high retaining wall was observed within the eastern half of the site
approximately 100 feet east of the residence and 75 feet north of the southern property line. Except for
some water in the irrigation pond, we did not observe surface water on site during our visit on May 23,
2005.
Subsurface Conditions
Geology: The geologic units for this site are shown on the Geologic Map of the Renton Quadranlg e, King
County, Washin on, by D. R. Mullineaux, (U.S.G.S., 1965)_ The site is mapped as Ground Moraine
Deposits (Qgt) which is further described as two types of till with varying densities. The till deposits are
described as an unsorted mixture of sand, silt, clay, and gravel. Our explorations generally encountered
silty sand consistent with the description of the ablation till of the Ground Moraine Deposit.
Explorations: The subsurface conditions within the site were explored on May 23, 2005 by excavating
eight test pits to depths ranging from 4.5 to 8.5 feet below the existing surface using a trackhoe. The
approximate locations of our explorations are shown on the Site Plan in Figure 2. A geologist from NGA
was present during the explorations, examined the soils and geologic conditions encountered, obtained
samples of the different soil types, and maintained logs of the test pits.
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Grant's Place
Renton, Washington
June 10, 2005
NGA File No. 712005
Page 3
The soils were visually classified in general accordance with the Unwed Soil Classification System,
presented in Figure 3. The logs of our test pits are attached to this report and are presented as Figures 4
and 5. We present a brief summary of the subsurface conditions in the following paragraph. For a
detailed description of the subsurface conditions, the test pits logs should be reviewed..
We encountered approximately 0.5 to 1.5 feet of loose topsoil at the surface in all of the test pits. Below
the topsoil, we encountered medium dense to dense, orangish-brown to grayish -brown, silty, fine to
medium sand with gravel, iron -oxide staining, and sand lenses. This soil was interpreted as glacial till.
All test pits were terminated in the till deposit. Minor to moderate caving was encountered in most of the
test pits.
Hydrologic Conditions
Minor to moderate groundwater seepage was encountered within all of the explorations at depths ranging
from 2.5 to 7.5 feet below the existing ground surface. It is our opinion that this seepage is perched
water. Perched water occurs when surface water infiltrates through less dense, more permeable soils and
accumulates on top of a relatively impermeable material such as the underlying silty sand. The more
permeable soils consist of the topsoil and the upper weathered zone of the till. Perched water does not
represent a regional groundwater "table" within the upper soil horizons. Perched water tends to vary
spatially and is dependent upon the amount of rainfall. We would expect the amount of perched water to
decrease during drier times of the year and increase during wetter periods. Due to the shallow occurrence
of groundwater in our explorations and the relatively level ground surface, we anticipate that groundwater
will be present on this site throughout the year.
SENSITIVE AREA EVALUATION
Seismic Hazard
Medium dense to dense glacial soils were encountered underlying the site. Based on the 2003
International Building Code (IBC), the site conditions best fit the description for Soil Class D_
Hazards associated with seismic activity include liquefaction potential and amplification of ground
motion by soft deposits. Liquefaction is caused by a rise in pore pressures in a loose, fine sand deposit
beneath the groundwater table. Ground motion amplification is caused by thick deposits of soft material.
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Grant's Place
Renton, Washington
June 10, 2005
NGA File No. 712005
Page 4
The medium dense to dense glacial till interpreted to underlie the site has a low potential for liquefaction
or amplification of ground motion.
Erosion. Hazard
The erosion hazard criteria used for determination of affected areas includes soil type, slope gradient,
vegetation cover, and groundwater conditions. The erosion sensitivity is related to vegetative cover and
the specific surface soil types, which are related to the underlying geologic soil units. The Soil Survey,
King County Area, Washington, by the Soil Conservation Service (SCS) was reviewed to determine the
erosion hazard of the on -site soils. The site surface soils were classified using the SCS classification
system as Alderwood gravelly sandy loam, 6 to 15 percent slopes. This unit is listed as having a
moderate erosion hazard. The site soils should have a low potential for erosion if not disturbed.
CONCLUSIONS AND RECOMMENDATIONS
General
It is our opinion, that from a geotechnical standpoint, the site is compatible with the planned
development. Our explorations within the site indicated that the site is generally underlain by competent
glacial till soils. These native soils should provide adequate support for the planned structure
foundations, slab -on -grade, and pavement. We recommend that the buildings be designed utilizing
shallow foundations. Footings should extend through any loose surficial soil or undocumented fill and be
founded on the underlying medium dense or better native soils, or structural fill extending to these soils.
Undocumented fill or loose soil could be encountered around the existing house and out buildings. Any
undocumented fill or soft/loose soil should be over -excavated as part of site preparation.
Coal mining has been conducted in the past in the general site vicinity. We did not observe nine shafts,
tailings, or other indications of mining operations on this site. Also, information collected at the
Washington State Department of Natural Resources did not indicate that mining operations were
specifically conducted on this site. We should note, however, that the reviewed DNR maps for coal mine
shafts and tunnels are based on old records that may not be entirely accurate.
The soils that are expected to be encountered during site development are considered highly moisture -
sensitive and can disturb in wet conditions. Wet soil and seeping water was observed in our explorations
NELSON GEOTECHIVICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Grant's Place
Renton, Washington
June 10, 2005
NGA File No. 712005
Page 5
at shallow depths. We recommend that the site be developed during the dry season. If construction takes
place during the rainy months, the site soils may disturb and become difficult to work. Also, if
construction takes place during the wet season, additional expenses and delays should be expected.
Additional expenses could include the need for placing a blanket of rock spalls on exposed subgrades,
construction traffic areas, and pavement areas prior to placing structural fill. NGA should be retained to
determine if the on -site soils could be used as structural fill material during construction.
We anticipate that wet conditions will be prevalent on this site throughout the year. We recommend that
footing and wall drains as well as underslab drains be incorporated in the design. Also, cut-off or French -
type drains might be needed at certain locations to maintain dry conditions.
Erosion Control Measures
The erosion hazard for the on -site soils is considered moderate, but will be dependent on how the site is
graded -and how water is allowed to concentrate. Best Management Practices (BMPs) should be used to
control erosion. Areas disturbed during construction should be protected from erosion. Measures taken
may include diverting surface water away from the stripped areas. Silt fences or straw bales should be
erected to prevent muddy water from leaving the site.
Temporary and Permanent Slopes
We do not anticipate major grading on this site as part of site improvements, however, if an underground
stormwater detention vault or a large detention pipe is used for handling stormwater runoff, temporary
cuts over four feet in height may be needed for the installation of these systems. Temporary cut slope
stability is a function of many factors, including the type and consistency of soils, depth of the cut,
surcharge loads adjacent to the excavation, length of time a cut remains open and the presence of surface
or groundwater. It is exceedingly difficult under these variable conditions to estimate a stable, temporary,
cut slope angle. Therefore, it should be the responsibility of the contractor to maintain safe slope
configurations since he is continuously at the job site, able to observe the nature and condition of the cut
slopes, and able to monitor the subsurface materials and groundwater conditions encountered.
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Grant's Place
Renton, Washington
June 10, 2005
NGA File No: 712005
Page 6
The following information is provided solely for the benefit of the owner and other design consultants and
should not be construed to imply that Nelson Geotechnical Associates, Inc. assumes responsibility for job
site safety. Job site safety is the sole responsibility of the project contractor.
For planning purposes, we recommend that temporary cuts in the native glacial till soils be no steeper
than 1.5 Horizontal to 1 Vertical (1.5H:IV). If significant groundwater seepage or sandier portions of the
till are encountered, we would expect that flatter inclinations would be necessary. We recommend that
cut slopes be protected from erosion. Measures taken may include covering cut slopes with plastic
sheeting and diverting surface runoff away from the top of cut slopes. We do not recommend vertical
slopes for cuts deeper than four feet, if worker access is necessary. We recommend that cut slope heights
and inclinations conform to appropriate OSHA/WISHA regulations.
Site Preparation and Grading
After the existing residence, trees, and ground cover have been removed, the next step of site preparation
should be to strip any topsoil or loose material to expose medium dense or better native soils in
foundation, pavement, and slab areas. Based on our observations, we anticipate an average stripping
depth of the topsoil to be one to two feet across the site. However, additional stripping may be required in
the vicinity of the existing residence and outbuildings, the pond, or in the unexplored areas where fill may
exist. If the ground surface, after stripping the unsuitable material and excavating down to planned
subgrade elevations appears to be loose, it should be compacted to a non -yielding condition and then
proof -rolled with a heavy rubber -tired piece of equipment. Areas observed to pump or weave during the
proof -roll test should be reworked to structural fill specifications or over -excavated and replaced with
properly compacted structural fill or rock spalls.
If significant surface water flow is encountered during construction, this flow should be diverted around
areas to be developed and the exposed subgrade maintained in a semi -dry condition. After the water has
been controlled, the site should be stripped and graded using large excavators equipped with wide tracks
and smooth buckets. The exposed subgrade should not be compacted, as compaction of a wet subgrade
may result in further disturbance of the native soils. Instead, a layer of crushed rock or all-weather
material may be placed over the prepared areas to protect them from further disturbance.
NELSON OEOTECHNICAL ASSOCIATES, INC
Geotechnical Engineering Evaluation
Grant's place
Renton, Washington
June 10, 2005
NGA File No. 712005
Page 7
If a detention system is used, it should be excavated down to planned elevations while maintaining the
recommended temporary excavation inclinations provided above. if groundwater seepage is encountered,
this water should be pumped out of the excavation and the bottom of the excavation be covered with a
minimum of six inches of crushed rock to reduce the potential for disturbing the sensitive subgrade and to
provide a clean work surface for vault or pipe placement.
As mentioned earlier, the site soils are considered highly moisture sensitive and can disturb when wet.
We therefore recommend that construction take place in the summer during periods of extended dry
weather, and suspended during periods of rainfall. If work is to take place during the wetter part of the
year, care should be taken during site preparation not to disturb the site soils. This can be accomplished
by utilizing large excavators equipped with smooth buckets and wide tracks to complete earthwork, and
diverting surface and groundwater flow away from the prepared subgrades. Also, construction traffic
should not be allowed on the exposed subgrade. A blanket of rock spalls should be used in construction
access areas if wet conditions are prevalent. The thickness of this rock spall layer should be based on
subgrade performance at the time of construction. For planning purposes, we recommend a minimum
one -foot thick layer of rock spalls.
Foundation Support
Conventional shallow spread foundations for building support should be placed on undisturbed medium
dense or better native soils or be supported on structural fill or rock spalls extending to those soils. Where
less dense soils are encountered at footing bearing elevation, the subgrade should be over -excavated to
expose suitable bearing soil. The over -excavation may be filled with structural fill, or the footing may be
extended down to the bearing native soils. If footings are supported on structural fill, the fill zone should
extend outside the edges of the footing a distance equal to one-half of the depth of the over -excavation
below the bottom of the footing.
Building footings should extend at least 18 inches below the lowest adjacent finished ground surface for
frost protection and bearing capacity considerations. Minimum foundation widths of 18 and 24 inches
should be used for continuous and isolated footings, respectively, but footings should also be sized based
on the anticipated loads and allowable soil bearing pressure. Standing water should not be allowed to
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Grant' s Place
Renton, Washington
June 10, 2005
NGA File No. 712005
Page 8
accumulate in footing trenches. All loose or disturbed soil should be removed from the foundation
excavation prior to placing concrete.
For foundations constructed as outlined above, we recommend an allowable design bearing pressure of
not more than 2,000 pounds per square foot (psf) be used for the building footing design for footings
founded on the medium dense or better native soils or structural fill extending to the native competent
material. The foundation bearing soil should be evaluated by a representative of NGA. We should be
consulted if higher bearing pressures are needed. Current IBC guidelines should be used when
considering increased allowable bearing pressure for short-term transitory wind or seismic loads.
Potential foundation settlement using the recommended allowable bearing pressure is estimated to be less
than one inch total and 1/2 inch differential between adjacent footings or across a distance of about 20
feet.
Lateral loads may be resisted by friction on the base of the footing and passive resistance against the
subsurface portions of the foundation. A coefficient of friction of 0.35 may be used to calculate the base
friction and should be applied to the vertical dead load only. Passive resistance may be calculated as a
triangular equivalent fluid pressure distribution. An equivalent fluid density of 250 pounds per cubic foot
(pcf) should be used for passive resistance design for a level ground surface adjacent to the footing. This
level surface should extend a distance equal to at least three times the footing depth. These recommended
values incorporate safety factors of 1.5 and 2.0 applied to the estimated ultimate values for frictional and
passive resistance, respectively. To achieve this value of passive resistance, the foundations should be
poured "neat" against the native medium dense to dense soils or compacted fill should be used as backfill
against the front of the footing. We recommend that the upper one -foot of soil be neglected when
calculating the passive resistance.
Structural Fill
General. Fill placed beneath foundations, pavement, or other settlement -sensitive structures should be
placed as structural fill. Structural fill, by definition, is placed in accordance with prescribed methods and
standards, and is monitored by an experienced geotechnical professional or soils technician. Field
monitoring procedures would include the performance of a representative number of in -place density tests
to document the attainment of the desired degree of relative compaction. The area to receive the fill
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Grant's Place
Renton, Washington
June 10, 2005
NGA File No. 712005
Page 9
should be suitably prepared as described in the Site Preparation and Grading subsection prior to
beginning fill placement.
Materials: Structural fill should consist of a good quality, granular soil, free of organics and other
deleterious material and be well graded to a maximum size of about three inches. All-weather fill should
contain no more than five -percent fines (soil finer than U.S. No. 200 sieve, based on that fraction passing
the U.S. 314-inch sieve). The use of on -site soils as structural fill should generally be feasible, but will be
dependent on material moisture content at the time construction takes place. Most of the on -site soils will
be very difficult to compact to structural fill specifications in wet conditions. Even in dry weather, some
moisture -conditioning of the on -site material night be required to attain compactable conditions. We
should be retained to evaluate proposed structural fill material prior to construction.
Fill Placement: Following subgrade preparation, placement of structural fill may proceed. All filling
should be accomplished in uniform lifts up to eight inches thick. Each lift should be spread evenly and be
thoroughly compacted prior to placement of subsequent lifts. All structural fill underlying building areas
and pavement subgrade should be compacted to a minimum of 95 percent of its maximum dry density.
Maximum dry density, in this report, refers to that density as determined by the ASTM D-1557
Compaction Test procedure. The moisture content of the soils to be compacted should be within about
two percent of optimum so that a readily compactable condition exists. It may be necessary to over -
excavate and remove wet soils in cases where drying to a compactable condition is not feasible. All
compaction should be accomplished by equipment of a type and size sufficient to attain the desired degree
of compaction.
Slab -on -Grade
Slabs -on -grade should be supported on subgrade soils prepared as described in the Site Preparation and
Grading subsection of this report. We recommend that all floor slabs be underlain by at least six inches
of free -draining sand or gravel for use as a capillary break. We recommend that the capillary break be
hydraulically connected to the footing drain system to allow free drainage from under the slab. A suitable
vapor barrier, such as heavy plastic sheeting (6-mil minimum), should be placed over the capillary break
material. Due to the wet site conditions, it might be prudent to utilize a system of underllab drains that
are in turn routed to the perimeter drains, to further reduce the potential for groundwater to produce damp
conditions in the dwellings.
NELSON GE'OTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Grant's Place
Renton, Washington
June 10, 2005
NGA File No. 712005
Page 10
Pavements
Pavement subgrade preparation, and structural filling where required, should be completed as
recommended in the Site Preparation and Grading and Structural Fill subsections of this report. The
pavement subgrade should be proof -rolled with a heavy, rubber -tired piece of equipment, to identify soft
or yielding areas that require repair. We should be retained to observe the proof -rolling and recommend
repairs prior to placement of the asphalt or hard surfaces.
Site Drainage
Surface Drainage: The finished ground surface should be graded such that stormwater is directed to an
appropriate stormwater collection system. Water should not be allowed to stand in any area where
footings or slabs are to be constructed. Final site grades should allow for drainage away from the
structures. We suggest that the finished ground be sloped at a minimum gradient of three percent, for a
distance of at least 10 feet away from the structures. Surface water should be collected by permanent
catch basins and drain lines, and be discharged into an appropriate discharge system.
Subsurface Drainage: If groundwater is encountered during construction, we recommend that the
contractor slope the bottom of the excavation and collect the water into ditches and small sump pits where
the water can be pumped out of the excavation and routed into a permanent storm drain.
We recommend the use of footing drains around the planned structure. Footing drains should be installed
at least one foot below planned finished floor elevation. The drains should consist of a minimum four -
inch -diameter, rigid, slotted or perforated, PVC pipe surrounded by free -draining material, such as
washed rock, wrapped in a filter fabric. We recommend that an 18-inch-wide zone of clean (less than
three -percent fines), granular material be placed along the back of the walls above the drain. Pea gravel is
an acceptable drain material or drainage composite may also be used instead. The free -draining material
should extend up the wall to one foot below the finished surface. The top foot of backfill should consist
of impermeable soil placed over plastic sheeting or building paper to minimize surface water or fines
migration into the footing drain. Footing drains should discharge into tightlines leading to an appropriate
collection and discharge point with convenient cleanouts to prolong the useful life of the drains. Roof
drains should not be connected to footing drains.
NELSON GEOTECHNIeAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Grant's Place
Renton, Washington
June 10, 2005
NGA File No, 712005
Page 11
Due to prevalent wet site conditions, cut -of or French -type drains may be required uphill of the planned
improvements to control groundwater and maintain semi -dry pads. The need and extent of such systems
should be determined in the field prior to the start of mass grading. Also, underslab drains might be
considered for this site. The underslab drain systems usually consist of 4-inch perforated lateral pipes
placed within the capillary break layer, 10 to 15 feet apart. The laterals are routed to a solid main
collector drain that in turn is routed into the footing drain system. We should be retained to review plans
for site drainage.
USE OF THIS REPORT
NGA has prepared this report for Tridor Inc., and their agents, for use in the planning and design of the
development planned on this site only. The scope of our work does not include services related to
construction safety precautions and our recommendations are not intended to direct the contractors'
methods, techniques, sequences, or procedures, except as specifically described in our report for
consideration in design. There are possible variations in subsurface conditions between the explorations
and also with time. Our report, conclusions, and interpretations should not be construed as a warranty of
subsurface conditions. A contingency for unanticipated conditions should be included in the budget and
schedule.
We recommend that NGA be retained to provide monitoring and consultation services during
construction to confirm that the conditions encountered are consistent with those indicated by the
explorations, to provide recommendations for design changes should the conditions revealed during the
work differ from those anticipated, and to evaluate whether or not earthwork and foundation installation
activities comply with contract plans and specifications. We should be contacted a minimum of one week
prior to construction activities and could attend pre -construction meetings if requested.
Within the limitations of scope, schedule, and budget, our services have been performed in accordance
with generally accepted geotechnical engineering practices in effect in this area at the time this report was
prepared. No other warranty, expressed or implied, is made. Our observations, findings, and opinions are
a, means to identify and reduce the inherent risks to the owner.
• i •
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Grant's Place
Renton, Washington
June 10, 2005
NGA File No. 712005
Page 12
It has been a pleasure to provide service to you on this project. If you have any questions or require
further information, please call.
Sincerely,
NELSON GEOTECHNICAL ASSOCIATES, INC.
;�Bala Dodoye-Alalz
Project Geologist
e
EXPIRES. J)<-
Khaled M. Shawish, PE
Principal
Five Figures Attached
NELSON GEOTECHNICAL ASSOCIATES, INC.
NOT TO SCALE
Project Number
712005
Figure 1
NELsoN GEOrecHNICAL
Grants Place �j(A AsSOCIATEs� INC.
GEOTECHNICAL ENGINEERS & GEOLOGISTS
Vicinity Map 1781'1_195hA— NE. Ad50 sno 11"I Cw,ay((azs ssr-2756
Woo&Mm, WANM Wenetcfiaa�p.* (so9j)7sa-27ss
(4Z)481 -4665l Fex4fH-2576 _..bongao9etlsaxn
Nod Date I Revision
1 i 51241W i Original
By ICK
--T-
ACO(3AD
\ 10 20
Reference: Site Plan based on an electronic plan dated May 25, 2005, titled "Grant's Place," prepared by Kovach Architects.
UNIFIED SOIL CLASSIFICATION SYSTEM
GROUP
MAJOR DIVISIONS
GROUP NAME
SYMBOL
CLEAN
GW WELL
-GRADED, FINE TO COARSE GRAVEL
COARSE-
GRAVEL
GRAVEL
GP
POORLY -GRADED GRAVEL
GRAINED
MORE THAN 50 %
GRAVEL
GM
SILTY GRAVEL
OF COARSE FRACTION
RETAINED ON
SOILS
NO.4 SIEVE
WITH FINES
GC
CLAYEY GRAVEL
SAND
CLEAN
SW WELL
-GRADED SAND, FINE TO COARSE SAND
SAND
SP
POORLY GRADED SAND
MORE THAN 50 %
RETAINED ON
MORE THAN 50 %
NO. 200 SIEVE
OF COARSE FRACTION
SAND�'(�
SILTY SAND
PASSES NO.4 SIEVE
SC
WITH FINES
CLAYEY SAND
FINE -
SILT AND CLAY
ML
SILT
INORGANIC
GRAINED
LIQUID LIMIT
CL
CLAY
LESS THAN 50 %
SOILS
ORGANIC
OL
ORGANIC SILT, ORGANIC CLAY
SILT AND CLAY
MH
SILT OF HIGH PLASTICITY, ELASTIC SILT
INORGANIC
MORE THAN 50 %
PASSES
LIQUID LIMIT
CH
CLAY OF HIGH PLASTICITY, FLAT CLAY
NO.200 SIEVE
50 % OR MORE
ORGANIC
OH
ORGANIC CLAY, ORGANIC SILT
HIGHLY ORGANIC SOILS
PT
PEAT
NOTES:
1) Field classification is based on visual
SOIL MOISTURE MODIFIERS:
examination of soil in general
accordance with ASTM D 2488-03.
Dry - Absence of moisture, dusty, dry to
the touch
2) Sol[ classification using laboratory tests
is based on ASTM D 24W93.
Moist - Damp, but no visible water.
ci
N
3) Descriptions of soil density or
Wet -Visible free water or saturated, o
consistency are based on
usually soil is obtained from ti
interpretation of blowcount data,
below water table
visual appearance of soils, and/or
test data.
o
0
N
Project Number
\ NIELSON GIEOT14Ct Nir-AL
No.
Date
I7evision
By
CK
712005
Grarlt�S Place
�` 1,,,
N A
ASSOCIATES, INC.
9
W4M
Original
ACO
N
BAD
Sail Classification
G+. EOTECHiNICAL ENG:INEERS & GEOLQGIs rs
.
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Figure 3
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en�,�,C�t,�,3V-1W9
Wenatcheek7heten ( r6aa755
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(445)4WM660/Fax45i-4610 www.nateo=
U'
LOG OF EXPLORATION
DEPTH (FEET) USC SOIL DESCRIPTION
TEST PIT ONE
0.0 -1.0 TOPSOIL (LOOSE, MOIST)
1.0 - 2.5 SM ORANGISH-BROWN TO BROWN, SILTY FINE TO COARSE SAND (MEDIUM DENSE, MOIST)
2.5-7.0 SM ORANGISH-BROWN TO BROWN, SILTY FINE TO COARSE SAND WITH GRAVEL AND
COBBLES (DENSE, MOIST)
7.0-8.5 SP-SM GRAY, FINE TO MEDIUM SAND WITH SILT ANDGRAVEL (DENSE, WET)
SAMPLE WAS COLLECTED AT 4.5 FEET
MINOR GROUNDWATER SEEPAGE WAS ENCOUNTERED AT 7.5 FEET
MINOR TEST PIT CAVING WAS ENCOUNTERED FROM 7.0 TO 8.5 FEET
TEST PIT WAS COMPLETED AT 8.5 FEET ON 5123/05
TEST PIT TWO
0.0- 0.5 TOPSOIL WITH ROOTS (LOOSE, MOIST)
0.5 -2.0 SM ORANGISH-BROWN, SILTY FINE TO MEDIUM SAND WITH GRAVEL
(MEDIUM DENSE, MOIST)
2.0 - 7.0 SM GRAY, SILTY FINE TO COARSE SAND WITH GRAVEL (DENSE TO VERY DENSE, MOIST)
SAMPLE WAS COLLECTED AT 3.2 FEET
MODERATE GROUNDWATER SEEPAGE WAS ENCOUNTERED AT 6.5 FEET
TEST PIT CAVING WAS NOT ENCOUNTERED
TEST PIT WAS COMPLETED AT 7.0 FEET ON 5/23/05
TEST PIT THREE
0.0 -1.0 TOPSOIL (LOOSE, MOIST)
1.0-2.5 SM ORANGISH-BROWN, SILTY FINE TO MEDIUM SAND (MEDIUM DENSE, MOISTTO WET)
2.5 - 7.0 SM GRAYISH -BROWN, SILTY FINE TO MEDIUM SAND (DENSE, MOIST TO WET)
SAMPLE WAS COLLECTED AT 2.0 FEET
MINOR TO MODERATE GROUNDWATER SEEPAGE WAS ENCOUNTERED AT 3.0 FEET
MINOR TEST PIT CAVING WAS ENCOUNTERED FROM 6.0 TO 7.5 FEET
TEST PIT WAS COMPLETED AT 7.0 FEET ON 5/23105
TEST PIT FOUR
0.0 -1.0 TOPSOIL (LOOSE, MOIST)
1.0 - 2.5 SM ORANGE, SILTY FINE TO MEDIUM SAND WITH GRAVEL
(LOOSE TO MEDIUM DENSE, MOIST TO WET)
2.5-4.5 SM ORANGISH-BROWN, SILTY FINE TO COARSE SAND WITH GRAVEL (DENSE, MOIST)
SAMPLES WERE NOT COLLECTED
MINOR TO MODERATE GROUNDWATER SEEPAGE WAS ENCOUNTERED AT 2.5 FEET
TEST PIT CAVING WAS NOT ENCOUNTERED
TEST PIT WAS COMPLETED AT 4.5 FEET ON 5/23/05
ACO:BAD NELSON GEOTECHNICAL ASSOCIATES, INC.
FILE NO 712005
FIGURE 4
LOG OF EXPLORATION
DEPTH (FEET)
TEST PIT FIVE
0.0 - 1.2
1.2 - 5.0
5.0-6.0
TEST PIT SIX
0.0 -1.0
1.0 - 3.0
3.0-5.0
TEST PIT SEVEN
0.0 - 1.0
1.0 - 2.5
2.5-6.5
TEST PIT EIGHT
0.0 - 1.5
1.5 - 6.0
ACO: BAD
USC SOIL DESCRIPTION
TOPSOIL (LOOSE, MOIST)
SM ORANGISH-BROWN, SILTY FINE TO MEDIUM SAND WITH GRAVEL
(MEDIUM DENSE, MOIST TO WET)
SM ORANGISH-BROWN, SILTY FINE TO MEDIUM SAND WITH SILT LAYERS AND IRON -OXIDE
STAINING (DENSE, MOIST)
SAMPLES WERE COLLECTED AT 3.0 ND 6.0 FEET
MINOR TO MODERATE GROUNDWATER SEEPAGE WAS ENCOUNTERED FROM 2.5 TO 6.0
FEET
MINOR TEST PIT CAVING WAS ENCOUNTERED FROM 0.0 TO 6.0 FEET
TEST PIT WAS COMPLETED AT 6.0 FEET ON 5/23/05
TOPSOIL (LOOSE, MOIST)
SM ORANGISH-BROWN, SLTY FINE TO MEDIUM SAND WITH GRAVEL
(MEDIUM DENSE, MOIST)
SM ORANGISH-BROWN, SILTY FINE TO MEDIUM SAND WITH IRON -OXIDE STAINING (MEDIUM
DENSE, MOIST TO WET)
SAMPLES WERE NOT COLLECTED
MODERATE GROUNDWATER SEEPAGE WAS ENCOUNTERED AT 3.0 FEET
MINOR TEST PIT CAVING WAS ENCOUNTERED FROM 4.0 TO 5.0 FEET
TEST PIT WAS COMPLETED AT 5.0 FEET ON 5/23/05
TOPSOIL (LOOSE, MOIST)
SM ORANGE, SILTY FINE TO MEDIUM SAND WITH ROOTS (MEDIUM DENSE, MOIST)
SM ORANGISH-BROWN, SILTY FINE TO MEDIUM SAND WITH GRAVEL AND IRON -OXIDE
STAINING (MEDIUM DENSE TO DENSE, MOIST)
SAMPLE WAS COLLECTED AT 4.0 FEET
MINOR GROUNDWATER SEEPAGE WAS ENCOUNTERED FROM 2.0 TO 6.5 FEET
MINOR TEST PIT CAVING WAS ENCOUNTERED FROM 2.5 TO 6.5 FEET
TEST PIT WAS COMPLETED AT 6.5 FEET ON 5/23/05
TOPSOIL WITH ROOTS (LOOSE, MOIST)
SM ORANGISH-BROWN, SILTY FINE TO MEDIUM SAND WITH SILT LAYERS AND IRON -OXIDE
STAINING (MEDIUM DENSE, MOIST TO WET)
SAMPLES WERE COLLECTED AT 2.0 AND 6.0 FEET
MINOR GROUNDWATER SEEPAGE WAS ENCOUNTERED AT 4.5 FEET
MINOR TEST PIT CAVING WAS ENCOUNTERED FROM 4.5 TO 5.0 FEET
TEST PIT WAS COMPLETED AT 6.0 FEET ON 5/23/05
NELSON GEOTECHNICAL ASSOCIATES, INC.
FILE NO 712005
FIGURE 5
Renton
GRANT PLACE TOWNHOMES
SITE ACCESSITRAFFIC IMPACT FEE TRAFFIC LETTER
January 21, 2014
JTE .Jake Traffic Engineering, Inc.
Mark J. Jacobs, PE, PTOE, President
2614 39�" Ave SW -Seattle, WA 98116 - 2503
Tel. 206.762.1978 -Cell 206.799.5692
E-mail iaketraffic@comcast.net
JTE.Jake Traffic Engineering Inc .
GRANT PLACE TOWNHOMES
Attn: Michael Chan
316 Maynard Ave. S. #101-105
Seattle WA 98104
Re: Grant Place Townhomes -Renton
Si[e Access/Traffic Impact Fee Traffic Letter
Mark J. Jacobs, PE, PTOE
President
2614 39�^ Ave. SW -Seattle, WA 981 I d - 2503
iel. 206.162.1978 -Cell 206.799.5692
E-maB jakemRm�wnitasLcet
January 21, 2014
Dear Mr. Chan,
I am pleased to submit this Site Access/Traffic Impact Fee Traffic Letter for the proposed 36
units Grant Place Townhomes project located at 1600 Grant Avenue South on parcel
#2023059052 in the City of Renton. Access to the site is provided via separate ingress and
egress only driveways on Grant Avenue South.
Prior to this report I prepared Gmnt Place Townhomes Site Access/Traffic Impact Fee
Analysis dated November 25, 2006. The Grant Place Townhomes project did not come to
fruition. Germaine data from my prior research on the site is incorporated into this letter.
I have reviewed the site and surrounding street system. The study scope was determined
pursuant with prior correspondence with the City of Renton, my prior work on the site and
review of the City's TIA Guidelines for new developments. The City peak hour trip threshold is
20 net new trips. The general format of this report is to describe the proposed project,
calculate the traffic that would be generated by the project, review the site accesses and
ascertain the Traffic Impact Fee for the project
The summary and conclusions are on page six of this report.
PROJECT INFORMATION
An aerial image of the site obtained
from King County IMap is to the
right:
Figure 1 is a vicinity map showing
the location of the proposed site
and surrounding street network.
Figure 2 shows a preliminary site
plan prepared by Milbrandt
Architects November 20, 2013.
JTE, Inc.
GRANT PLACE TOWNHOMES
Attn: Michael Chan
January 21, 2014
Page -2-
The plan consists of the project layout comprising of 36 townhome units to be built housed in
8 buildings. Internal circulation is also shown. Access to the site Is provided via an entry
only and an exit only driveway on Grant Avenue South.
Full development and occupancy of the proposed Grant Place Townhomes project Is
anticipated to occur by 2015/16, presuming the permits are issued in a timely manner.
EXISTING ENVIRONMENT
Project Site
The project site Is located on parcel #2023059052 and is presently developetl with one
existing single family tlwelling unit. This existing housing unit would be removed to make way
for the subject project. Additional Information on this parcel is attached in [he appendix.
Street Svstem
Figure 3 shows the existing traffic control, number of street lanes, number of approach lanes
at the intersections and other pertinent information. The primary streets within the study
area and their classifications per the City of Renton Comprehensive Plan are as follows:
Y S. Puget Dr. Minor Collector
➢ Grant Avenue South Unclassified
D S. 18�^ St. Unclassified
Grant Avenue South is a two lane street with a posted speed limit of 25 MPH. An advisory
curve warning speed of 20 MPH is identified for the horizontal street curvature in the vicinity
of the project site.
Traffic Volumes
The City of Renton Traffic Flow Mao, 2010 indicates the 2010 daily traffic on Grant Ave. S. at
2,000 to 2,500 vpd in the site vicinity.
Pedestrian Facilities
Curb, gutter and sitlewalk exist on both sides of 108�^ Ave. SE (SR - 515).
drools
Renton School District identified students living in the Grant Place Townhomes woultl attend
the following schools:
➢ Talbot Hill Elementary School - 2300 Talbot Road S, Renton, WA 98055
➢ Dimmit Middle School - 12320 80th Avenue S, Seattle, WA 98178
➢ Renton High School - 400 S 2nd St, Renton, WA 98057
Students attending the above schools would be eligible for bus transportation.
JTE, Inc.
GRANT PLACE TOWNHOMES
Attn: Michael Chan
January 21, 2014
Page -3-
Accident History
WSDOT electronically provided 3 years 11 months (January 1, 2010 to November 31, 2013)
of accident data for Grant Avenue S. from S. Puget Drive to Beacon Way South. I have
reviewed the data; the data indicates 3 recorded incidents (inattention, improper backing
and under the influence) on Grant Ave. S. between S. Puget Drive and Beacon Avenue South.
STREET IMPROVEMENT PROJECTS
The City of Renton 6 vear Transportation Improvement Proeram, 2013 to 2018 was
reviewed. No TIP project is noted on Grant Avenue South. I have included the project map
index in the Appendix of this letter. The 6 year TIP is available on the City's web site.
TRIP GENERATION AND DISTRIBUTION
Definitions
A vehicle trip is defined as a single or one direction vehicle movement with either the origin
or destination (existing or entering) inside the proposed development.
Traffic generated by development projects consists of the following types:
Pass -By Trips: Trips made as intermediate stops on the way from an origin to
a primary trip destination.
Diverted Link Trips: Trips attracted from the traffic volume on roadways within the
vicinity of the generator but require a diversion from that
roadway to another roadway to gain access to the site.
Captured Trips: Site trips shared by more than one land use in a multi -use
development.
Primary (New) Trips: Trips made for the specific purpose of using the services of
the project.
Trio Generation
The proposed Grant Place Townhomes project is expected to generate the vehicular trips
during the average weekday, street traffic AM and PM peak hours as shown in Table 1. The
trip generation for the project is calculated using trip rates from the Institute of
Transportation Engineers (ITE) Trio Generation, 9N Edition, for Single Family Detached
Housing and Residential Condominium/Townhouse (ITE land Use Code 210 and 230,
respectively). All site trips made by all vehicles for all purposes, including commuter, visitor,
and service and delivery vehicle trips are included in the trip generation values.
Residential Condominium/Townhomes generate predominantly primary trips. There would
be some captured/pass-by trips that alreatly exist within the vicinity; such as mail delivery,
garbage, and other service/delivery traffic. One existing single family dwelling unit exist on
JTE, Inc.
GRANT PLACE TOWNHOMES
Attn: Michael Chan
January 21, 2014
Page -4-
the site. Credits towards this single family dwelling unit were taken from the proposed Grant
Place Townhomes.
Based on our analysis, the trips generated by the Grant Place Townhomes project are
calculated to be 199 net new daily and 18 net new trips during the PM peak hour.
SITE ACCESS SIGHT DISTANCE
I field inspected, using a measuring wheel, the available stopping sight distance (SSD) and
entering sight distance (ESD) at the proposed site access. The north site access is to be
Ingress only and the south access egress only.
The SSD was measured to a 2 ft. high object "vehicle tail light" standards. The 2 ft. object
height is per the American Association of State Highway and Transportation Officials
(AASHTO). Prior correspondence with the City of Renton Identified that they use the
American Association of State Highway and Transportation Officials (AASHTO) criteria for
sight distance.
The results of the field measurements are summarized in Table 2. Table 2 shows the
stopping and entering sightdlstance standards per the identified MPH at the proposed
Ingress and egress driveways. The stopping and entering sight distance were obtained from
the American Association of State Highway and Transportation Officials (AASHTO) A Policv on
Geometric Design of Hi2hways an Streets, 2001 Fourth Edition "Exhibit 9-55. Design
Intersection Sight Distance -Case B1 -Left Turn from stop' (attached in the appendix).
Grant Avenue Scuth has a posted 25 MPH speed limit. An advisory speed sign of 20 MPH is
also identifietl along the bend on Grant Avenue S. in the vicinity of the proposed project.
Table 2 itlentifies the stopping and entering sight distance for the posted (25 MPH) speed
limi[and the advisory (20 MPH) speed.
Below are pictures at the proposed site accesses; ingress only and egress only.
North Site Driveway (Ingress Only)
JTE, Inc.
GRANT PLACE TOWNHOMES
Attn: Michael Chan
January 21, 2014
Page -5-
The critical AASHTO criterion is Stopping Sight Distance for the ingress only driveway.
Motorists need to have sufficient sight lines to see vehicles turning into the site. Ample SSD
is available at the proposed Ingress only driveway.
Appropriate "Enter Only" signage neetls to installed at the ingress only driveway. And
conversely signage that states "NO EXIT ALLOWED" needs to be installed.
South Site Driveway (Egress Only)
The above photographs were taken from the existing driveway about 15' north of the
proposed driveway. The new driveway location would remove the existing Cedar Tree seen in
the photograph looking south. The egress only driveway provides the more critical SSD that
exceeds the criterion fora 25 MPH speed. Egress motorists have sufficient ESD based on
the advisory speed of 20 MPH.
Parked vehicles affect sight lines. No parking should be allowed in the near vicinity of the
proposed egress driveway. A 30 feet "No Parking" zone to the north and south of the
proposed egress driveway is recommended. The 30' dimension Is consistent with field data I
have observed over the years.
Additionally, signage at the egress driveway needs to identify that the driveway is "Exit Only".
Summary:
Based on my analysis the proposed ingress only on Grant Avenue South meets the AASHTO
stopping sight distance criteria. At the egress driveway the more critical SSD is met for the
posted speed limit of 25 MPH and ESD criterion is met for the advisory speed of 20 MPH.
Pruning/removinguegetation looking to/from the north to greater enhance sight visibility is
recommended. Pruning/removingthe vegetation in the right-of-way would increase the
entering sight distance to/from the north by -25 feet.
JTE, Inc.
GRANT PLACE TOWNHOMES
Attn: Michael Chan
January 21, 2014
Page -&
AGENCY TRAFFIC IMPACT MITIGATION REQUIREMENTS
The City of Renton has a Traffic Impact Fee program per Ordinance #5670 effective January
1, 2013. The TIF is scheduled to be phased in over time. The Pre-aonlication Meetine Notes
identify the 2014 TIF at $$789.44 per TH; and a TIF of $1,430.72 per SFDU. A TIF of
$26,989.12 ($28,419.84 (36 - TH's) - $1,430.72 (1-Existing SFDU to be removed)) is thus
tletermined. This fee adjusts annually and is scheduled to go up in 2015.
Access improvements per City requirements will be required.
Construct the internal street in conformance to City requirements.
SUMMARY AND CONCLUSION
This letter was prepared to identify the Trip Generation of the proposed project, review the
Site Access Sight Lines and calculate the City's Traffic Impact Fee. Based on my analysis the
proposed Grant Place Townhomes project is expected to generete 199 net new daily and 18
net new PM peak hour trips. The City trip threshold is 20 ......... no City classified
intersection would be effected by site traffic. The proposed site ingress with Grant Avenue
South meets the AASHTO sight distance criteria fora 25 MPH speed Ilmit. The egress
driveway meets the critical SSD and the AASHTO entering sight distance criteria for the
advisory speed of 20 MPH. A traffic impact fee of $26,989.12 is calculated [o be
contributed to the City of Renton's traffic impact fee program.
Based on my analysis I recommend that Grant Place Townhomes be allowed with the
followingtraffic impact mitigation measures.
D Construct site in accordance with applicable City requirements.
➢ Conduct a survey to verify the site access sight lines prior to Preliminary Plat
Approval.
➢ Provide an appropriate vegetation clearing removal in the ROW.
➢ A 30 feet "No Parking" zone to the north and south of the proposed egress driveway.
1 Install appropriate "Enter Only" and "NO EXIT ALLOWED" at the ingress driveway and
"Exit Only" signage at the egress driveway.
➢ Pay lawful traffic impact mitigation fee.
Please contact me at 206.762.1978 or email me at iaketraffic�comcast.net if you have any
questions.
Sincerely,
Mark J. Jacobs, PE, PTOE, President
IAKE TRAFFIC ENGINEERING, INC
JTE, Inc.
VEHICULAR TRIP GENERATION
TABLE 1
GRANT PLACE TOWNHOMES - RENTON
SITE ACCESS/TRAFFIClMPACT FEE TRAFFIC LETTER
TIME
PERIOD
TRIP
RATE
TRIPS
ENTERING
TRIPS
EXITING
TOTAL
Single Family Deta
hed
ousing (ITE Land Use Cotle 210, one lot) -Existing
Average Weekday
T= 9.52X
5 (50%)
5 (50%)
10
AM Peak Hour
T = 0.75X
0 (25%)
1(75%)
1
PM peak Hour
T = 1.00X
1(63%)
0 (37%)
1
Residential Contlo
iniu
ownhouse (ITE Land Use Cotle 230, 36 units) -Proposed
Averege Weekday
T = 5.81X
105 (50%)
104 (50%)
209
AM Peak Hour
T = 0.44X
3 (17%)
13 (83%)
i6
PM peak Hour
T = 0.52X
13 (67%)
6 (33%)
19
Total (Proposed -
isti
g)
Average Weekday
100
99
199
AM Peak Hour
3
12
15
PM peak Hour
-
12
6
16
T =trips
X = number of ots lots
A vehicle trip i def ned as a single or one direction vehicle movement with either the origin
or destination exis ing or entering) inside the study site.
The above trip en ration values account for all the site trips made by all vehicles for all
purposes, incl din commuter, visitor, recreation, and service and delivery vehicle trips
JTE, Inc.
SIGHT DISTANCE SUMMARY
TABLE 2
GRANT PLACE TOWNHOMES - RENTON
SITE
ACCESS/TRAFFIC IMPACT FEE TRAFFIC
LETTER
AASHTO Criteria
Looking Looking
(MPH)
Grant
Ave ue South
to/from the to/from the
north south
Advisory
Posted
20 MPH
25 MPH
North Site
Access (Ingress
Only)
Stopping
Sigh}Distance (ft.)
-180' -280'
115'
155'
Not Applicable
-
-
225'
280'
South Site
Access (Egress
Only)
Stopping
Sight Distance (tt.)
-230'
-165'
115'
155'
Entering
Sight Distance (ft.)
-210'; _235'�
'
225'
280'
� -235'i
i - Pruning removing the vegetation in the right-of-way would increase the entering sight distance
to/from the north by -25 feet
� -Sight line with existing Cetlar Tree removed
Project: Grant Place Townhomes -Renton
Location: 1fi00 Grant Avenue South
NORTIi
-_ ni. ,, € a � � � � �
{� a z r
s � � z a �
� � se r t
"` � � S � _
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sf � Ff hs ��',v 3 sE fam a��W
JTE, I11C. GRANT PLACE TOWNHOMES - RENTON
FIGURE 1 SITE ACCESS/TRAFFIC IMPACT FEE TRAFFIC LETTER
VICINITY MAP
Project: Grant Place Townhomes -Renton
Location: 1600 Grant Avenue South
NORTH
Milb�a�At Arghwt e.Uy, I`n cy, P.L r �� _ s�P
Note: An 8.5 x Si' copy of the Site Plan Is inclutletl with Nis letter report.
JTE, IIIC. GRANT PLACE TOWNHOMES - RENTON
FIGURE 2 SITE ACCESS/TRAFFIC IMPACT FEE TRAFFIC LETTER
SITE PLAN
m
wilmom ml
�� Washington State rrnnwonaaon ewmina
�// Da artmont of 7Yans rtation 310 Maple Park Avanua S.E.
P i� P.O. Boz 4)300
gymPle. WA 965o4-]300
Lynn Peterson 360-]05-]000
SecrHary of Transponation TIM. 1-Boo-tq3-6366
www.wsEotwa.gov
January 13, 20I4
Mr. Mark 1. Jacobs —JTE Inc
2614 39a' Ave S W
Seattle WA 98116
Re: Collision Data
Dear Mr. Jacobs:
In response to your January 6 request, we have prepared a history of officer reported collisions that
occurred on or in the vicinity of Gmnt Ave in the City of Renton for the period of 1/ I /2010 — 11/30/2013
(November oj20/3 is the mos! current complete momh proces•.ved).
Federal law 23 United States Code Section 409 governs use ofthe data you requested. Under this law,
data maintained for purposes of evaluating potential highway safety enhancements:
... shot! not he suhject to discovery or admitted into evidence in a federal or state
court proceeding or considered jor other purposes in any action jor damages arising
from any occurrence at a location mentioned or addressed in such reports, surveys,
schedules, lists, or data." [Emphasis added.]
The Washington State Department of Transportation (WSDOT) is releasing this data to you with the
understanding that you will not use this data contrary to the restrictions in Section 409, which means you
will not use this data in discovery or as evidence at trial in any action for damages against the WSDOT,
the State of Washington, or any otherjurisdiction involved ur the locations mentioned in the data. If you
should attempt to use this data in an action for damages against WSDOT, the State of Washington, or any
other jurisdiction involved in the locations mentioned in the data, these entities expressly reserve the right,
under Section 409, to object to the use of the data, including any opinions drawn from the data.
If you have any further questions you may contact me at 360-570-2490.
Sincerely,
Geneva Hawkins
Collision Data Analyst
Statewide Travel &Collision Data Office /Multi -modal Planning Division
N
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7% glaahbrgipp state Request for Collision Data
Deparlmerd o1 7Yansportation
Please complete this request loan and mail or fax to the address shown below. In order to ensure efficient service.
please provide as much information es you can in your request If can ram�ira addainnal information In rmm�late
your request, we will contact you.
The Washington State Department of Transportation maintains a statewide database for all reported imffc
collisions, beginning with collisions occurring in 2002. In addition. collision data for interstate and state highways
only is available for collisions occurring from 1993 to the present. This data includes such items as collision
location, dale, time, seventy, weather and light conditions, as well as information on tlrivers, pedestrians, bicyGists
and property owners involved in collisions.
Federal highway safety laws require the state to create this collision database for use In obtaining fetleral
safety Improvement (ands. Under Section 409 of Title 23 of the United States Code, collision data is
prohib{led from use in any litigation against slate, tribal or local government that involves the locations)
mentioned in the collision data. By checking the hox helow, you agree to comply with Mese temps -failure
to do so will be grounds for denying your request.
�I hereby affirm that I am not requesting this collision data for use in any current, pending or anticipated
litigation against slate. tribal or local govemment involving a collision at the localion(s) mentioned in the data.
Requestor Information
Lest Name
�A C
aQS
First N
�'Z/�r2�
M
Company/Agency Name
J
1NC
Atltlress
3 s h i¢„� S�
City S�
stale
u�
zip Cade
9Pii6
Phone No.
Fax No.
Email
Description of Collision Data Requested
Use the space below Ie descdbe your request. II applicable, please include the following.
• Beginning and entling dales for the desired data.
• Names of locations or individual highways, roads or streets desired.
• In what format you would like the data. e.g.. a history report that gives mformalion about each
wllision; a summary report by year or by month', or a summary for specific data elements, such as
light wnd9lons, That were experienced during the collisions.
3 �-s.�� �e0/o-2dyL.�'t ..✓.,�.Le Luy3 fay /Le.:��., Vr
Mail or Fax your completed request form to-.
COLLISION DATA 8 ANALYSIS BRANCH
WASHINGTON STATE DEPARTMENT OF TRANSPORTATION
P.O. BOX 4]3e1 3 � � r l f —&
OLVMPIA WA 96504-47381 e O I ,�.� Z� J � '� f a,�
Fax: 360-570-2449 'l •1 I t
If you have any questions, please call (360) 570-2454 yl ,.� I � I� /J
oor a�,'mB6vxoo`s L [ .-y i " 0.�11�"'
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V11. Other Permits
Other permits include water and sewer franchise utility permits and right of way
improvement permit as required by the City of Renton.
47
Vill. CSWPPP Analysis and Design
ESC Plan Analysis and Design (Part A)
TEMPORARY EROSION AND SEDIMENT CONTROL
1. The grading for this project is only limited to the onsite improvement and offsite
frontage improvement. Temporary Erosion and Sedimentation Control will be
provided by utilizing BMPs selected from the 2009 King County Surface Water
Design Manual. These BMPS will likely include, but are not necessarily limited to
construction entrance for traffic stabilization, silt fencing for parameter protection,
plastic sheeting of stockpiles, straw mulch, hydro -seeding of exposed areas, catch
basin protection, etc. All new impervious areas and new pervious areas will be
treated by a combined detention/wet vault for Level 2 flow control and treated by
a treatment train of wet vault and StormFilter manhole for enhanced basic water
quality treatment. At the beginning of the construction, construction entrance and
silt fence along the grading limit will be installed. Then, combined detention/wet
vault will be installed. The excavation of the vault and the vault itself can be used
as temporary sediment trap during construction period. Temporary erosion and
sediment control facilities will be maintained during construction period and will be
removed after construction is finished. See Temporary erosion and sediment
control plan, notes and details at the construction plan set for more details. Also
see attached Stormwater Pollution Prevention and Spill (SWPPS) plan.
2. The site is hilly, no sensitive area exist onsite. No special measure is proposed.
Temporary sediment trap sizing:
Q2y using KCRTS method with 15-minute time step:
48
' Lend Use Summary I o ( ' -' 1 J
.._area -- ?
Till Forest 0.00 acres
Till Pasture 0.00 acres
Till Grass 0.73 acres
Outwash Forest 0.00 acres
Outwash Pasture 0.00 acres
Outwash Grass 0.00 acres
Wetland 0.00 acres
Impervious 1.38 acres
2.11 acres
Scale Factor: 1.00 15-Min Reduced
Edit Flow Paths
Time Series: Rev-l5.tsf }}
Compute Time Series
Modify User Input
Flow Frequency Analysis
Time Series File:dev-15.tsf
Project Location:Sea-Tac
---Annual
Peak
Flow Rates ---
Flow Rate
Rank
Time of
Peak
(CFS)
0.657
6
8/27/01
18:00
0.464
8
1/05/02
15:00
1.41
2
12/08/02
17:15
0.529
7
8/23/04
14:30
0.791
4
11/17/04
5:00
0.783
5
10/27/05
10:45
0.916
3
10/25/06
22:45
2.00
1
1/09/08
6:30
Computed Peaks
-----Flow
Frequency
Analysis
--
- - Peaks
- - Rank Return
Prob
(CFS)
Period
2.00
1
100.00
0.990
1.41
2
25.00
0.960
0.916
3
10.00
0.900
0.791
4
5.00
0.800
0.783
5
3.00
0.667
0.657
6
2.00
0.500
0.529
7
1.30
0.231
0.464
8
1.10
0.091
1.80
50.00
0.980
Q2y = 0.657 cfs
Required surface area = 2080 * Q2y = 2080 * 0.657 = 1,367 sf.
The proposed temporary sediment trap is located at the northwest corner of the site. A
temporary overflow path is provided to over flow to the existing 12" CMP culvert inlet at
the Grant Avenue South near existing catch basin SDMH#1.
49
EROSION AND SEDIMENT CONTROL STANDARDS:
ESC measures shall be applied and maintained to prevent, to the maximum extent
practicable, the transport of sediment from the project site to downstream drainage
systems or surface waters. This performance is intended to be achieved through
proper selection, installation, and operation of the above ESC measures as detailed
in the ESC Standard (detached Appendix D) and approved by the City of Renton.
PERMANENT EROSION AND SEDIMENT CONTROL
For Permanent Erosion and Sedimentation Control, access driveways, fire lane and
walkways will be paved. Landscape areas will be covered with grass, trees and ground
covers. All onsite new impervious areas and new pervious areas will be treated by the
combined detention/wet vault for Flow control (Level 2, forest existing condition) and a
treatment train of combined detention/wet vault and StormFilter manhole with CSF
cartridges for Enhanced Basic water quality treatment.
50
STORMWATER POLLUTION PREVENTION AND SPILL (SWPPS) PLAN
(Part B)
51
Stormwater Pollution Prevention Plan for Construction
STORM WATER POLLUTION PREVENTION PLAN
GRANT AVENUE TOWNHOMES
RENTON, WASHINGTON, USA
Prepared for
Northwest Regional Office
3190 - 160th Avenue SE
Bellevue, WA 98008-5452
425-649-7000
May 30, 2017
Prepared by
Pacific Engineering Design, LLC.
15445 53rd Avenue South, Suite 100
Seattle, WA 98188
Phone: (206) 431-7970
PED Job number: 13043
SWPPP
Pacific Engineering Design, LLC.
Storm Water Pollution Prevention Plan for Construction Activities
I certify under penalty of law that this document and all attachments were prepared under
my direction or supervision in accordance with a system designed to assure that qualified
personnel properly gathered and evaluated the information submitted. Based on my
inquiry of the person or persons who manage the system, or those persons directly
responsible for gathering the information, the information is, to the best of my knowledge
and belief, true, accurate and complete. I am aware that there are significant penalties for
submitting false information, including the possibility of fine and imprisonment for
knowing violations.
�� D /z ol
Jingsong,g, P.E'.
Project Engineer
SITE CONTACT INFORMATION
SITE OWNER
PHONEIFAX/MOBILE
ADDERSS
Skyline Properties, Inc.
(425) 455-2065
50116t1' Avenue SE, Suite 120
Bellevue, WA 98004
PROJECT CONTRACTOR
To be determined
PROJECTEROSIONLEAD
24 HOUR CONTACT
To be determined
To be determined
Pacific Engineering Design, LLC.
Storm Water Pollution Prevention Plan for Construction Activities
Revision Schedule
This storm water pollution prevention plan (SWPPP) should be revised and updated to
address changes in site conditions, new or revised government regulations, and additional
on -site storm water pollution controls.
All revisions to the SWPPP must be documented on the SWPPP Revision Documentation
Form, which should include the information shown below. The authorized facility
representative who approves the SWPPP should be an individual at or near the top of the
facility's management organization, such as the president, vice president, construction
manager, site supervisor, or environmental manager. The signature of this representative
attests that the SWPPP revision information is true and accurate. Previous authors and
facility representatives are not responsible for the revisions.
SWPPP Revision Documentation Form
Number
Date
Author
Company
Representative
Signature
0
1
2
3
4
5
6
7
8
9
10
Pacific Engineering Design, LLC.
CONTENTS
LIST OF FIGURES AND DRAWINGS
iv
1
CONSTRUCTION ENVIRONMENTAL SUMMARY
1-1
1.1 Summary
1-1
2
INTRODUCTION
2-1
2.1 Storm water Pollution Prevention Plan Requirements
2-1
2.2 Purpose
2-1
2.3 SWPPP Organization
2-1
3
CLEARING LIMITS
3-1
3.1 Site Plans
3-1
3.2 Marking Clearing Limits
3-1
3.3 Special Consideration
3-1
3.4 Selected BMPs
3-1
4
CONSTRUCTION ACCESS
4-1
4.1 Site Access
4-1
4.2 Street Cleaning
4-1
4.3 Wheel Wash
4-1
4.4 Selected BMPs
4-1
5
STORM WATER DETENTION
5-1
5.1 Primary Storm water Detention System
5-1
5.2 Run-on Bypass
5-1
6
SEDIMENT CONTROLS
6-1
6.1 Site Sediment Control System
6-1
6.2 Selected BMPs
6-1
7
SOIL STABILIZATION
7-1
7.1 Soil Stabilization
7-1
7.2 Structural BMPs
7-2
8
SLOPE PROTECTION
8-4
8.1 General Practices
8-4
8.2 Suggested BMPs
8-4
Pacific Engineering Design, LLC.
i
CONTENTS (Continued)
9 DRAIN INLET PROTECTION 9-1
9.1 Existing Storm Drains 9-1
9.2 Newly Constructed Storm Drains 9-1
9.3 Suggested BMP 9-1
10
STORM WATER OUTLET PROTECTION
10-1
10.1
Street Drainage along the west side of 141h Avenue SW
10-1
10.2
Bypass Drainage along the west side of 141h Avenue SW
10-1
10.3
Suggested BMPs
10-1
11
SPILL PREVENTION AND RESPONSE
11-1
11.1
General Materials Handling Practices
11-1
11.2
Specific Materials Handling Practices
11-2
11.3
Spill Response
11-2
11.4
Notification
11-4
12
STORM WATER TREATMENT
12-1
12.1
Storm Water Collection System
12-1
12.2
Temporary Sediment Traps
12-1
12.3
Monitoring Chemical Treatment System
12-1
12.4
pH Adjustment
12-2
13
BMP
MAINTENANCE
13-4
14
PROJECT MANAGEMENT
14-1
14.1
Phasing of Construction
14-1
14.2
Seasonal Work
14-1
14.3
Training
14-1
14.4
Pre -construction Conference
14-2
14.5
Coordination with Utilities and other Contractors
14-2
14.6
Subcontractor Oversight
14-2
14.7
Monitoring/Reporting
14-2
14.8
SWPPP Update
14-2
FIGURES
DRAWINGS
ii
Pacific Engineering Design, LLC.
CONTENTS (Continued)
APPENDIX A NPDES STORM WATER PERMIT FOR CONSTRUCTION
& STATE WATER QUALITY STANDARDS
APPENDIX B STANDARDS AND SPECIFICATIONS FOR SELECTED
BMPs
APPENDIX C MATERIAL SAFETY DATA SHEETS
Pacific Engineering Design, LLC.
iii
FIGURES AND DRAWINGS
Figures
1 Site Topography Map
2 Storm water Site Map
Drawings
C01
Cover Sheet
CO2
Overall Plat Plan
CO3
Grading and Drainage Plan
C04
Composite Utility Plan
C05
Tree Retention Plan
Following Report
Pacific Engineering Design, LLC.
1v
Storm Water Pollution Prevention Plan for Construction Activities
1 CONSTRUCTION ENVIRONMENTAL SUMMARY
1.1 Summary
Beginning in Summer 2016, Skyline Properties, Inc. is starting the Grant Avenue
Townhomes construction project located on 1600 Grant Avenue South in City of Renton,
Washington. The site area is 2.11 acres. The existing residence on the site will be
removed for this development. The project will construct 8 new multi -family apartment
building complexes (total 36 units), access roads and walkways, street frontage
improvement with new sidewalk along Grant Avenue South, landscaping and associated
utilities.
Duration (forest existing condition) flow control and Enhanced Basic water quality
treatment are required for this project. A combined detention/wet vault is used to provide
the required Flow control. A treatment train of combined detention/wet vault and
StormFilter manhole with CSF cartridges is used to provide the required water quality
treatment. The conveyance system is designed to have the capacity to handle 100 year 24
hour peak flow.
There is no sensitive area in the site or near the site. Because more than 5,000 square feet
of new impervious area is proposed, extra protective measures have been established to
ensure there is no adverse impact to water quality in the surrounding area. This Storm
water Pollution Prevention Plan details all of the protective environmental measures,
which will be employed during construction of the project.
Perhaps most innovative and protective of all measures designed for use is the storm
water treatment system which treats all storm water collected during construction to
produce clear, clean, and non -toxic water for discharge into the drainage basin stream.
Designed as an integrated Best Management Practice (BMP) to complement the other
BMPs described in this plan, the storm water treatment system provides a fail-safe
method for ensuring only clean water leaves the site.
1.1.1 Project Description
Total project area is 2.17 acres (2.11 acres onsite, 0.06 acres offsite frontage
improvement). Total proposed impervious area is 1.41acres (1.38 acres onsite, 0.03 acres
offsite), proposed areas to be disturbed is 2.17 acres (2.11 acres on site, 0.06 acres
Pacific Engineering Design, LLC.
1-1
Storm Water Pollution Prevention Plan for Construction Activities
offsite). Total volumes of proposed cuts are approximately 4,240 cy and total volumes of
proposed fill are approximately 3,680 cy. Net earth work exported is approximately 560
cy.
1.1.2 Existing Site Conditions
There is a single family house (built 1946) on the west portion of the site near the Grant
Avenue South. The house will be demolished and removed for the proposed
development. The remainder of the property is covered with grass with some scattered
trees. The site is hilly with average slope of 11 % slopes westerly toward Grant Avenue
South.
The properties east and south of the site have their own drainage system to intercept
runoff before it reach the site. The property north of the site slopes westerly to Grant
Avenue South parallel with the site. The properties west of the site are located at
elevations lower than the site. The site does not receive significant upstream runoff from
adjacent properties.
Under existing condition, the site sheet flows westerly to Grant Avenue South. The low
point of Grant Avenue South is located near the northwest corner of the site where there
are two type 1 catch basins at both sides of the street to collect street runoff. The street
drainage system drains to a storm manhole (SDMH#1) near the northwest corner of the
site. SDMH#1 has an 18" outfall pipe that discharges westerly to Thunder Hills Creek.
The 0.25 mile downstream point is located at the Thunder Hills Creek. The 1 mile
downstream point is located at the city storm drainage system that drains to Springbrook
Creek.
No capacity problem, erosion problem and water quality problem were found within 0.25
miles downstream of the site.
1.1.3 Adjacent Areas
Adjacent areas that may be affected by the runoff of sediment -contaminated water are the
Grant Avenue South and the Thunder Hills Creels directly west of the site. Under
developed condition, onsite runoffs will be collected and conveyed to the onsite
detention and water quality treatment system before discharged to the Grant Avenue
South storm drainage system and Thunder Hills Creek. During construction, silt fences
will be installed along the south and west property lines of the site to prevent sediment -
contaminated runoff leaving the site. Excavation for the combined detention/wet vault
will be used as temporary erosion and sediment pond. Temporary intercept ditches will
be installed to intercept onsite runoff and direct it to this temporary erotion and sediment
pond.
Pacific Engineering Design, LLC.
1-2
Storm Water Pollution Prevention Plan for Construction Activities
1.1.4 Critical Areas
There is no critical area in the site or near by the site.
1.1.5 Soils
According to the City of Renton Soils Map and King County Soils Map, on site soil is till
soil (Alderwood Gravelly sandy loam, Agl) (15 to 30% slope) on the west portion of the
site and AgC (8 to 15% slope) on the east portion of the site) and infiltration is not
feasible for this site.
1.1.6 Erosion Problem Areas
The site is hilly with average slope of approximately II% across the site. Potential for
erosion problem is moderate on the east portion of the site and severe on the west portion
of the site. The west portion of the site is mapped as erosion hazard area on the City of
Renton Erosion Hazard Area Map and moderate landslide hazard area on the City of
Renton Landslide Hazard Area Map.
1.1.7 Construction Phasing
The construction may be divided to two phases:
Onsite development.
2. Offsite frontage improvement.
1.1.8 Construction Schedule
The construction will happen in dry season total construction time will be 5 to 6 month.
If wet season land disturbance is proposed, see section VIII of this TIR for wet season
special provitions.
1.1.9 Financial/Ownership Responsibilities
The property owner is responsible for the initiation of bonds and/or other financial
securities and the bonds and/or other evidence of financial responsibility for liability
associated with erosion and sedimentation impacts.
Pacific Engineering Design, LLC.
1-3
Storm Water Pollution Prevention Plan for Construction Activities
1.1.10 Engineering Calculations
See section IV of this TIR for the design calculations for the sizing of storm water
detention facilities and storm water treatment facilities. See section V of this TIR for the
sizing of the conveyance system.
Pacific Engineering Design, LLC.
1-4
Storm Water Pollution Prevention Plan for Construction Activities
2 INTRODUCTION
2.1 Storm water Pollution Prevention Plan Requirements
This Storm water Pollution Prevention Plan (SWPPP) is developed consistent with the
requirements of the National Pollutant Discharge Elimination System (NPDES) General
Storm water Permit for Construction Activities (see Appendix A for a copy of the general
permit). This SWPPP meets the requirements of Special Condition S9 of the general
permit. The primary consideration determining the adequacy of the SWPPP is
compliance with State Surface Water Quality Standards (Chapter 173-201A — see
Appendix A).
The Plan, properly implemented, should result in the discharge of water to the
environment without the violation of Water Quality Standards.
2.2 Purpose
The purpose of this SWPPP is to:
• Describe best management practices (BMPs) to minimize erosion and sediment
runoff at the site
• Identify, reduce, eliminate, or prevent the pollution of storm water
• Prevent violations of surface water quality or groundwater quality standards
2.3 SWPPP Organization
This plan consists of a detailed narrative section and the appendices, which contain
illustrations, maps, and drawings. The narrative section includes descriptions of potential
pollution problems associated with site features, and then discusses the selection of
specific pollution prevention BMPs to reduce or eliminate the threat of causing pollution
during the actual construction project. The illustrations, maps, and drawings in the
appendices show the site location, topography, sensitive environmental receptors,
placement of BMPs, and BMP specifications and performance expectations.
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The narrative section of this plan is organized in numbered sections around the
12 required elements of an SWPPP listed below:
1. Mark project clearing limits
2. Establishing the construction entrance(s)
3. Storm water detention
4. Selection and installation of sediment controls
5. Soil stabilization
6. Slope protection
7. Drain inlet protection
8. Storm water outlet protection
9. Chemical spill prevention and response
10. Site Storm water Treatment
11. BMP maintenance
12. Project management
In the narrative section, each of the above elements will be discussed in relation to the
specific conditions at the development. BMPs for each element will be screened,
resulting in selection of those BMPs deemed most appropriate for use. Specifications and
engineering drawings of the selected BMPs are referenced at the end of each section and
can be found in Appendix B.
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3 CLEARING LIMITS
3.1 Site Plans
Figure 1 is a topographic map of the site showing all natural drainages associated with
the area. Figure 2 is the Storm water Site Map showing any surface water in the area and
showing placement of all relevant storm water BMPs such as combined detention/wet
vault, storm drains, spill kit locations, storm water treatment system location, etc
3.2 Marking Clearing Limits
Prior to beginning earth -disturbing activities, including clearing and grading, all clearing
limits, easements, setbacks, sensitive areas and their buffers, trees and drainage courses
will be clearly marked to prevent environmental damage both on and off site.
3.3 Special Consideration
Special consideration will be given to the boundaries of the drainage basin on the site.
3.4 Selected BMPs
• BMP C 101: Preserving Natural Vegetation (total 11 existing trees and
surrounding vegetation will be preserved)
• BMP C103: Plastic or Metal Fence
• BMP C104: Stake and Wire Fence (used to marls temporary construction limits)
• BMP C233: Silt Fence
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4 CONSTRUCTION ACCESS
4.1 Site Access
Two temporary stabilized construction entrance will be installed at the location of the two
proposed driveway entrances near the southwest and northwest corners of the site. All
construction vehicles exiting the site will be limited to these accesses. The accesses are
stabilized with gravel to prevent tracking sediment onto Grant Avenue South.
4.2 Street Cleaning
If sediment is accidentally transported on to the street it will be removed from the street
surface on a daily basis. Sediment will be shoveled and/or swept from the street and
disposed of in a manner, which prevents contamination with storm water or surface water
(e.g., covered soil stockpile). In addition, a street sweeper may be used to maintain clean
roads on an as -needed basis.
4.3 Wheel Wash
Based on site conditions and time of year, a temporary truck wheel wash station may be
constructed to ensure control of sediment at the construction exit point. The wheel wash
system (if needed) will be constructed on the site at a location just prior to where trucks
leave the site access and enter the street. The system will consist of an asphalt -lined
wash pond for immersing the truck tires as the truck drives through and a small settling
pond for settling suspended sediment in wash water cycled out of the system. Wash
water may be reused after settling, infiltrated onsite, or transported off site for disposal.
Accumulated sediments will be collected periodically, stockpiled for dewatering, then
reused onsite.
4.4 Selected BMPs
• BMP C 105: Stabilized Construction Entrance
• BMP C 106: Wheel Wash (wet season only)
• BMP C 107: Construction Road/Parking Area Stabilization
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5 STORM WATER DETENTION
5.1 Primary Storm water Detention System
The construction site slopes westerly towards Grant Avenue South. Under developed
condition, The onsite detention tanks will provide Level 2 (Duration with forest existing
condition) Flow control for the project site. During construction period, The excavation
for the combined detention/wet vault will be used as a temporary erosion and sediment
control pond, all storm water contaminated with sediment or otherwise affected by
construction activities will be directed to this temporary erosion and sediment control
pond. The detained release will be discharged to the Grant Avenue South storm drainage
system which is discharged to the Thunder Hills Creek.
5.2 Run-on Bypass
No significant upstream area drains to the site. No BMPs are selected.
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6 SEDIMENT CONTROLS
6.1 Site Sediment Control System
Before being discharged from the construction site, sediment -contaminated storm water
will be processed in the storm water treatment system. Clean water bypassing the site
will be routed directly to the Grant Avenue South receiving storm drainage system. A
temporary erosion and sediment control pond will be installed near the west property line
using the excavation for the combined detention/wet vault. After the vault is constructed,
the vault itself can be used for temporary erosion and sediment control. Sediment
barriers or filters, and other BMPs intended to trap sediment on site will be constructed as
one of the first steps in grading. These BMPs will be installed before other land -
disturbing activities take place.
6.2 Selected BMPs
• BMP C200: Interceptor dike and swale
• BMP C207: Check dams
• BMP C233: Silt Fence
• BMP C241: Temporary Sediment Pond
• BMP C250: Construction Storm water Chemical Treatment
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7 SOIL STABILIZATION
This section describes the stabilization and structural BMPs that will be implemented to
minimize erosion and transport of sediment from the project site into receiving waters.
Erosion and sediment control facilities that have been approved as a part of the project's
grading permit are shown in Drawing of the Temporary Erosion and Sediment Control
Plan.
Many of the BMPs listed below are described in the WSDOT Construction Site Erosion
and Spill Control Certification Course Manual as well as in Volume 2 of Ecology's
Storm water Management Manual for the Puget Sound Basin and the King County
Surface Water Management Manual and have been included in Appendix B.
7.1 Soil Stabilization
Stabilization BMPs to be implemented at this site include:
• Soil Covering. All exposed soils will be stabilized with vegetation or covered
prior to the onset of the rainy season. The primary stabilization method used will be
covering soils with an approved matting and/or hydroseeding. This will be done on
all slopes as well as drainage ditches, swales, and exposed flat surfaces as deemed
necessary by the erosion and sediment control lead. Virtually all exposed soils will
be stabilized to protect surface water quality. Areas of the project, which have not
been properly stabilized by vegetation by the onset of the wet season, will be
covered with transparent plastic sheeting to prevent sediment transport. Plastic
sheeting will also be used as an emergency BMP to cover previously stabilized
areas, which begin to erode. Loose straw and mulch covers are not to be used as
they may be washed into drainage structures.
• Stockpile Covering. All temporary soil stockpiles will be covered with plastic.
Long-term stockpiles will be compacted and hydroseeded prior to the onset of wet
weather. Clean runoff from covered or stabilized stockpiles will be collected in solid
wall drainage pipe and conveyed to a surface water drainage structure.
• Polymer Soil Treatment. Smaller areas of the site may be actively worked
throughout the wet season to support the installation of utilities. These smaller areas
of exposed soils may be temporarily stabilized with the application of a granular
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anionic polyacrylamide (PAM). PAM may be applied as an aqueous solution
(0.5 pounds per 1,000 gallons of water) or as a granular solid evenly dispersed over
the surface of soils using a seed spreader (3 to 5 pounds of PAM per acre). For
additional instruction and use restrictions see the WSDOT Draft Experimental BMP
5.0 - Polyacrylamide for Soil Erosion Prevention (June 21, 1999) and the WSDOT
Draft Interim Criteria for WSDOT to use Polyacrylamide (PAM) (June 21, 1999) in
Appendix B.
• Maintenance of Existing Vegetation. Existing and new vegetation will be
maintained to the maximum extent practicable to prevent the contamination of storm
water with sediment. Vegetated areas beginning to show signs of erosion or soil
transport will be covered with plastic sheeting and the clean runoff conveyed to a
storm water drain.
• Outlet Protection. Adequate energy dissipation, erosion control, and soil
stabilization measures (e.g., rock or other energy dissipation techniques) will be
provided for all point source discharges of storm water, including run-on discharges
and outlets from onsite discharges.
• Inlet protection. All existing storm drain inlets, including those made operable
during the project, will be properly protected and maintained using approved inlet
protection devices.
7.2 Structural BMPs
Structural BMPs. Structural BMPs are practices designed to divert flows from
exposed soil, store storm water runoff, and limit runoff and the discharge of pollutants
from exposed areas of the project. The goal of structural BMPs on this project is to
protect receiving water downstream of the site from turbid water, phosphorus, sediment,
oil, and other contaminants, which may mobilize in storm water flows.
• Temporarily Modified Catchment Structures. Catch basins, manholes, vaults
and swales may have to be modified on a temporary basis so that dirty water can be
intercepted before leaving the site. This may be done in several different ways
generally resulting in temporarily blocking an outlet structure and installing a pump
to transfer the storm water inflow to a settling, infiltration, or treatment system.
Automatic float level controllers built into the pump prevent the pump from running
dry and conserve power use.
• Drainage Swales, Ditches, and Check Dams. Swales and ditches will be
used on a permanent and temporary basis to convey storm water in a way that
minimizes the potential for contamination by sediment. Because some sediment will
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always be present in storm water, check dams will be used in swales and ditches to
reduce the velocity of the water and allow some settling of larger particles.
• Sedimentation Swales and Ponds. Temporary and permanent swales and
small sedimend ponds will be used as necessary to reduce the velocity of runoff and
enhance particle settling.
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8 SLOPE PROTECTION
8.1 General Practices
Cut and fill slopes on this project have been designed and will be constructed so as to
minimize erosion. Soil types have been analyzed and considered for their potential to
erode also. In addition, slope runoff velocities will be reduced by terracing, creating
diversions, and surface contouring.
Upslope drainage and uncontaminated run-on water from off -site will be intercepted at
the top of the slope and diverted around the active construction area. Down slope flows
will be contained in pipes, slope drains, and/or stabilized channels.
8.2 Suggested BMPs
Because the site is hilly, slope protection is required for this project. The following
BMPs are selected.
• BMP C120: Temporary and Permanent Seeding
• BMP C 121: Mulching
• BMP C130: Surface Roughening
• BMP C131: Gradient Terraces
• BMP C200: Interceptor dike and swale
• BMP C204: Pipe Slope Drains
• BMP C207: Check dams
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9.1 Existing Storm Drains
Existing storm drain inlets will be protected to prevent storm water from entering without
first being filtered or treated to remove sediment.
9.2 Newly Constructed Storm Drains
All storm drain inlets made operable during construction will be protected to prevent
storm water from entering without first being filtered or treated to remove sediment.
9.3 Suggested BMP
• BMP C220: Storm Drain Inlet Protection
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10 STORM WATER OUTLET PROTECTION
10.1 Street Drainage along the east side of Grant Avenue South
Storm water will be cleaned of sediment and other pollutants when discharged from the
site to the storm drainage system that runs along the east side of GrantAvenue South.
The onsite storm drainage system will be connected to the Grant Avenue South storm
drainage system at existing SDMH#1 near the northwest corner of the site.
10.2 Bypass Drainage along the east side of Grant Avenue
South
Offsite runoff is intercepted by the existing storm drainage system that runs along the east
side of Grant Avenue South and bypass the site.
10.3 Suggested BMPs
• BMP C220: Storm Drain Inlet Protection.
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U \_ •'Ll I • p • •
Consistent with the general permit requirements, all potential pollutants other than
sediment will be handled and disposed of in a manner that does not cause contamination
of storm water. Non -sediment pollutants that may be present during construction
activities include:
• Petroleum products including fuel, lubricants, hydraulic fluids, and form oils
• Polymer used for soil stabilization
• Water treatment chemicals (coagulant, acid, sodium bicarbonate)
• Concrete
• Paints
• Fertilizers
These materials, and other materials used during construction with the potential to impact
storm water, will be stored, managed, used, and disposed of in a manner that minimizes
the potential for releases to the environment and especially into storm water.
Emergency contacts for the project will be posted at the project office and are included at
the end of this section.
11.1 General Materials Handling Practices
The following general practices will be used throughout the project to reduce the
potential for spills.
• Potential pollutants will be stored and used in a manner consistent with the
manufacturer's instructions in a secure location. To the extent practicable, material
storage areas should not be located near storm drain inlets and should be equipped
with covers, roofs, or secondary containment as needed to prevent storm water from
contacting stored materials. Chemicals that are not compatible (such as sodium
bicarbonate and hydrochloric acid) shall be stored in segregated areas so that spilled
materials cannot combine and react.
• Materials disposal will be in accordance with the manufacturer's instructions and
applicable local, state, and federal regulations.
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• Materials no longer required for construction will be removed from the site as soon
as practicable.
• Adequate garbage, construction waste, and sanitary waste handling and disposal
facilities will be provided to the extent necessary to keep the site clear of obstruction
and BMPs clear and functional.
11.2 Specific Materials Handling Practices
• All pollutants, including waste materials and demolition debris, that occur on -site
during construction will be handled in a way that does not contaminate storm water.
• All chemicals including liquid products, petroleum products, water treatment
chemicals, and wastes stored on site will be covered and contained and protected
from vandalism.
• Maintenance and repair of all equipment and vehicles involving oil changes,
hydraulic system drain down, de -greasing operations, fuel tank drain down and
removal, and other activities which may result in the accidental release of
contaminants, will be conducted under cover during wet weather and on an
impervious surface to prevent the release of contaminants onto the ground.
Materials spilled during maintenance operations will be cleaned up immediately and
properly disposed of.
• Wheel wash water will be settled and discharged on site by infiltration. Wheel wash
water will not be discharged to the storm water system or the storm water treatment
system.
• Application of agricultural chemicals, including fertilizers and pesticides, will be
conducted in a manner and at application rates that will not result in loss of chemical
to storm water runoff. Manufacturers' recommendations will be followed for
application rates and procedures.
• pH -modifying sources will be managed to prevent contamination of runoff and
storm water collected on site. The most common sources of pH -modifying materials
are bulls cement, cement kiln dust (CKD), fly ash, new concrete washing and curing
waters, waste streams generated from concrete grinding and sawing, exposed
aggregate processes, and concrete pumping and mixer washout waters.
11.3 Spill Response
The primary objective in responding to a spill is to quickly contain the material(s) and
prevent or minimize their migration into storm water runoff and conveyance systems. If
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the release has impacted on -site storm water, it is critical to contain the released materials
on site and prevent their release into receiving waters.
If a spill of pollutants threatens storm water at the site, the spill response procedures
outlined below must be implemented in a timely manner to prevent the release of
pollutants.
• The site superintendent will be notified immediately when a spill, or the threat of a
spill, is observed. The superintendent will assess the situation and determine the
appropriate response.
• If spills represent an imminent threat of escaping ESC facilities and entering the
receiving waters, facility personnel will respond immediately to contain the release
and notify the superintendent after the situation has been stabilized.
• Spill kits containing materials and equipment for spill response and cleanup will be
maintained at the site. Each spill kit may contain:
— Oil absorbent pads (one bale)
— Oil absorbent booms (40 feet)
— 55-gallon drums (2)
— 9-mil plastic bags (10)
— Personal protective equipment including gloves and goggles
• If an oil sheen is observed on surface water (e.g., settling ponds, detention pond,
swales), absorbent pads and/or booms will be applied to contain and remove the oil.
The source of the oil sheen will also be identified and removed or repaired as
necessary to prevent further releases.
• The site superintendent, or his designee, will be responsible for completing the spill
reporting form and for reporting the spill to the appropriate state or local agency (see
Forms at the end of this section).
• Facility personnel with primary responsibility for spill response and cleanup will
receive training from the site superintendent. This training will include identifying
the location of spill kits and other spill response equipment and the use of spill
response materials.
• Spill response equipment will be inspected and maintained as necessary to replace
any materials used in spill response activities.
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11.4 Notification
In the event of a spill, make the appropriate notification(s) consistent with the following
procedures:
• Any spill of oil which 1) violates water quality standards, 2) produces a "sheen" on a
surface water, or 3) causes a sludge or emulsion must be reported immediately by
telephone to the National Response Center Hotline at (800) 424-8802.
• Any oil, hazardous substance, or hazardous waste release which exceeds the
reportable quantity must be reported immediately by telephone to the National
Response Center Hotline at (800) 424-8802.
• Any spill of oil or hazardous substance to waters of the state must be reported
immediately by telephone to the Washington State Department of Ecology at (360)
407-6000 (Olympia), (425) 649-7000 (Bellevue).
• Any release of a hazardous substance that may be a threat to human health or the
environment must be reported to the Washington State Department of Ecology at
(360) 407-6000 (Olympia), (425) 649-7000 (Bellevue) immediately upon discovery.
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12 STORM WATER TREATMENT
12.1 Storm Water Collection System
During all phases of construction and grading the contractor will provide storm water
collection and conveyance systems to collect and direct sediment contaminated water to
temporary sediment pond as needed to prevent offsite discharge of sediment laden storm
water. Construction will occur in phases as much as practicable to avoid unnecessarily
exposing vegetated areas of the site. Clean storm water, generated from stabilized and
undisturbed portions of the site, will be collected and conveyed to stabilized discharge
areas whenever necessary to avoid contact with disturbed portions of the site. All
conveyance and collection systems will be constructed consistent with State and local
BMP requirements.
12.2 Temporary Sediment Traps
During construction, sediment contaminated storm water will be conveyed to temporary
sediment traps, as designed by the project engineer and shown on the temporary erosion
and sediment control (TESC) plan. The sediment traps will gravity -settle large particles
down to silt size particles. Considering subsurface soil types, it is unlikely that gravity
settling alone will remove all suspended particles. If settled storm water does not meet
state water quality standards, the storm water will be managed by chemical treatment.
An experienced expert in storm water treatment will perform chemical treatment. Many
of the chemicals utilized for this type of treatment (polymers) can be environmentally
hazardous.
12.3 Monitoring Chemical Treatment System
As with all effective BMPs, the chemical treatment system requires regular monitoring to
assure the overall effectiveness of storm water management. The key monitoring
requirements of the chemical treatment water management system include:
• Sediment Trap/pond Monitoring
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All sediment trap(s)/pond(s) should be visually monitored at least daily during the wet
season or as needed to monitor the level and quality of water within the sediment traps.
The site operator will designate site personal to routinely monitor the level of the
sediment trap such that the water level is not allowed to reach levels approaching
discharge. The sediment traps will also be monitored weekly or as needed for sediment
accumulation, functionality, and for other required maintenance. In the event of abnormal
conditions, site personal will immediately report the information to the site
superintendent for resolution.
• Pump and Mechanical System Monitoring
The pump or pumps that operate the storm water management system require routine
monitoring to ensure the continual performance of the system. The contractor will follow
all manufactures recommended inspection and maintenance procedures throughout the
life of the project. During the wet season, site personal will monitor pump systems for
correct operation, adequate power supply, and correct float level control operation.
Severe storm events may require more frequent inspections, especially if pumps rely on
utility -supplied power. The contractor will have available onsite or within reasonable
distance to site 24-hour-a-day available backup equipment including but not limited to a
pump and generator. In the event of mechanical equipment failure, the site operator will
immediately take all necessary actions to replace any malfunctioning components so as to
restore the original capacity of the water management system.
• Water Quality Monitoring
Water quality monitoring will be performed to demonstrate that the water management
process is working properly, to document the quality of water discharged to the stream,
and to document the background water quality of the stream. The effectiveness of the
water management system will be monitored on a daily basis, recorded on the Water
Management Log form, and reported to regulatory authorities as needed.
State water quality standards require treated water to not exceed 5 NTU above the
receiving water and the pH to be within 0.3 pH units of the receiving water. Therefore,
the Storm water Monitoring Form will be used to record the receiving water background
turbidity and pH as well as the quality of water discharged from the site. This
information can then be used to document compliance with water quality standards.
12.4 pH Adjustment
The most likely pH upset condition will be high pH resulting from concrete
contamination. Acid or dry ice (CO2) will be required to neutralize the high pH. Begin
recirculating the water in the basin to be neutralized while slowly adding acid (dry ice).
Acid (dry ice) quantity will be calculated based on a sample test neutralization.
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Caution! Hydrochloric and sulfuric acids are powerful acids, which can cause serious,
permanent damage to human skin and eyes. See Material Safety Data Sheets in
Appendix D. Goggles, gloves, and protective clothing are mandatory when handling
acid. An eye wash unit is stationed in the job trailer. Acid must always be stored,
moved, and dispensed in the secondary unit containment provided. No more than
5 gallons of acid will be stored on site at any time.
Check pH in the treatment basin frequently after incremental additions of acid or dry ice
to ensure the pH is not over -adjusted. Adjust the pH to 7.0 to 7.5. Once the desired pH
has been achieved, let the basin settle briefly and check the pH again.
A low pH condition may be treated by adding a 20 percent sodium bicarbonate solution
as above. Check the pH after incremental additions of sodium bicarbonate. The sodium
bicarbonate quantity may be calculated based on a simple jar test to determine the correct
amount for size of the pond.
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13 BMP MAINTENANCE
All temporary and permanent erosion and sediment control BMPs will be maintained and
repaired as needed to assure continued performance of their intended function. All
maintenance and repair will be conducted in accordance with BMPs. Recommended
BMP maintenance requirements are listed in Tables 1 and 2 included in this section.
Following Tables 1 and 2 is a BMP Inspection Checklist for use in routine inspections of
the construction site.
All temporary erosion and sediment control BMPs will be removed within 30 days after
final site stabilization is achieved or after the temporary BMPs are no longer needed.
Trapped sediment will be removed or stabilized on site. Disturbed soil areas resulting
from removal of BMPs or vegetation will be permanently stabilized as soon as possible.
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14 PROJECT MANAGEMENT
Implementation and management of the environmental aspects of this project under the
SWPPP are the responsibilities of The Development Company and the prime contractor.
Communication between all parties performing work on the site is essential for proper
implementation of the SWPPP. The prime contractor, utility installation contractor, and
grading contractor should all be familiar with the SWPPP and their responsibilities under
the plan. To help delegate these responsibilities the following outline has been provided:
14.1 Phasing of Construction
The project has been planned at this point in two phases to reduce the environmental
impact of mass grading. Phase one will result in the development of the offsite
improvement. During this time the site will remain undisturbed most of the time. Once
the offsite improvement phase is nearing completion the onsite improvement phase will
begin. From the beginning of construction until the completion of phase two, the storm
water treatment system will remain operational to purify storm water impacted by
construction activities.
14.2 Seasonal Work
The storm water treatment system has been designed to allow for work on the project
during the winter months without impacting the water quality in the drainage basin to the
west of the site. While not seasonal, some construction activities may need to be
postponed if scheduled during ongoing storm events. Activities such as grading and
trenching in areas directly adjacent to the drainage basin during rainstorms could easily
result in sediment -contaminated storm water reaching the stream. This work would
therefore be performed within a window of dry weather predicted on the basis of weather
reports.
14.3 Training
The Development Company will provide onsite training to key personnel responsible for
compliance with the SWPPP. The contractor's superintendent and project manager will
be familiarized with the major elements of the plan. Construction workers and others at
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the site will be given appropriate training information at the conclusion of site safety
meetings or on an as -needed basis.
14.4 Pre -construction Conference
One or more pre -construction meetings will be held with an explicit agenda item
addressing the SWPPP.
14.5 Coordination with Utilities and other Contractors
All contractors providing services on the project which may cause storm water pollution
will be given a copy of the SWPPP and appropriate training regarding storm water
pollution prevention.
14.6 Subcontractor Oversight
Subcontractor oversight to ensure compliance with the SWPPP will be provided by the
prime contractor's superintendent or project manager.. Informal, on-the-job tailgate
training will be the first level of communication followed by onsite observation of
training compliance. Non-compliance with SWPPP policies will trigger a more intensive
training session to correct the problem(s). Chronic non-compliance with SWPPP policies
may require the intervention of local and/or state regulatory personnel.
14.7 Monitoring/Reporting
Water quality conditions at the site will be monitored by a qualified technician and water
quality reports submitted to the proper regulatory authorities on a regular basis.
Additional reports such as erosion and sediment control inspections will be the
responsibility of the prime contractor or a designated consultant. Spill reports will be
completed and submitted by the prime contractor on the project.
The SWPPP will be updated as requested by The Development Company.
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FIGURES
Here include Figure 1 (Site Topographic Map)
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Here Include Figure 2 (Storm water Site Map)
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DRAWINGS
Here include appropriate engineering drawings
such as temporary esc, detention basin, tire wash,
construction entrance%xit or any other drawings
prepared specifically for the project.
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it. THE RUIEPROVID ENTENS THECAT DMIL VM1ETS OdIMSLOPENIONTMW 50B FEET OFA DISNRBEO OR COtSTRUCTIONARE+,,UMF.53
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-
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12 NAY BE UGEO ANYN'HEREA0EAREAPUCAMSDIELAR OtITOPROTECTDRA2IAGE SYSTELL
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NOTES
SITEANO
PAVED ROADS OR OTHER PAVED AREAS YARIIN TWO FEETDFTHE S(rE.
S
£ __=-_
----�'
Y'
13 THE COERRIBOfiNO ORABUGE AREA bgST NOT BE LARGER TtWJ1ACRE
1, CONDRmNOF USE
-
�_______---__-__---_
I
2. DE9pN Alm WSTALGTICN BPECffIGTpN3
1A, SILTFENCEMAYBEUSEDDOWNSLOPE OFALLDLSTURBEDAREAS,
I
21. FILTER FABRCIS CNLYALLOWED WT:RE PONDING WLLttOT BEATRAFFlCCONCEMPHD VMERE SLOPE EROSION VJRI NOT RESULT IF THE
12 ttOT INTEttDEDTO TREATCGICFWTRATEO ROWS, NOR I92NENOEDTO TREATSUBSTANRALAMWM90FOVERWmFLdW.
SaTFENCEE
AM CONCENTRATED FLOW MOST BE COlNEYEDTHROUGNIHE OR/JNAGE SYSTEM TDASEOMEMTRM ORPONO.
ALLEY BUASTSiu FNGiH n5TNO3l%SD1 atD 5A1.0.R
ADs1AnM w30 mm1Ui SInNOARDStVE MEI
^- I T-rti=rtr-
I
CUFETOPPED BY PONOED WATER
21. THEPLACE PLACENEMOFA FILTER FABWC UNDER GRATES ICI GENERALLY PROMBREOMDIHE USE OF Fe.TER FADWCOJER GRATES IS STRICTLY
LllAREO AND DISCOUftAGEA
2, DE81GNM0W8TALGDONBPEGFMATIQY9
2. DESIGNANDWSTALLATIONSPECIFICATIONS
E a+FTE ��
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3. NABtTENANCE STANDARDS
21. THEGEOTEXT EUSEDNOSTM£TTHESTA40ARDUSTEDBELLONACOMOFTHEbWA1FACRR SFMMSPEC£MATIONSM BE
AVAILABLE ON SITE
2.1. BSTMREO AREA THAT\Yi11BOTDE USED
iN WAARYSIN
FUEL M1'.'COD SASED MULCMMIS
may, ) F Cy ®
xy py
].1. AMACATER DTBE INLET S SHALL.NOT eE REIAOJED
aml�aluo=nU
URBAN
ENTROADS H0E3 FUEL IS NOT RECOLIAIENDED FOR ENTRANCE SIASU]ATIOtIWURBAH AREAS ASP CT NAY
FOR NOT ELI FO ENTRANCE
FOR PE
ATTIMEREQUWETHEUSEDFQUARRYSPMLS FTHEHOGFUELISNDTPREVENRNGSEDIMETRFROMMINGTRACKEDOWDWATER
m ra Saks RBq T°y
AND fi3 BE. MENT OFSITEULEUE00.1AED�ATELY.SEDWENT
MOALL SEDMENT b81ST BE 043POSEOOF AS FlLLGI SITE OR HAIAEOPAVEMENTORIFTHEHOGFUELLSBEING
M
CARRIEDDNTOPAVEMENT.22.FENCINGSHALLBEINSTALLEDASNECESSARY TO RESTRICT TRAFFIC TO THE CONSTRUCTION ENNWiCE
23. WHENEVER POSSIBLE, THE ENTRANCE SHALL BE CONSTRUCTED ON A FIU2, COMPACTED SUBGRADE THIN CAN SUBSTANTIALLY
INCREASE THE EFFECTIVENESS OF THE PAD AND REDUCE THE NEED FOR MAINTENANCE,
NOTES
1, CONDIDONOFUSE
3. NNNTEHANCE STANDARDS
i.t. ABEOAIFM FVIm 6HALL BE OSEO WTETEIHECONTRDUi1N0 DRAINAOEMEA 133ACRE80R VCRE
22 STANDARD SlRFNGIH FABRC REWJ2E3 WJEERACiGNGTOIJCREA3ElHESTRENGTH OF THE FENCE WWEBAC!(WGOR Cl1ISER POST
9PACWOIMY BE FEQVWED FOR EXRA 9IRENGIHFABRCF FIELD PERFORI.MVKE WARRANBABTRONGER FENCE
3.1 QUIT SPALLSSMMBEADDMFW EPADBWWNGMNACCORDANCEV"THESPECIIGTION3
32 TF THE ENTRANCE IS NDTPREVENTING SEDIMENT BEING TRAINED q'2T0 PAVEMEM,TNEN ALTERNATIVE MEASURES TD VEEP THE
2. Dp10NAND W3TAt1ATIQYBPEGFIGTgNB
2S WHER'c THE FENCEISWST ,,THESLOPESH WTBEBTEEPERTI IV
STREETS FREE OF SEDIMEMSHALL BE USED THIS MAYINCLUDE STREET SWEEMNG. AN WCREASE W THE DIMENSIONS DFTHE
21, THEPCNDSHALLBEDMOEDIMOTYIOROW!4YEOEW.VOWM'e CE BYAP'cM@ABI ERTH4TY REOUCETURBULENC -AS
2<. IFATYPICAL SRT FEMCE LS USED, THESTPNDAR04%OTRENCH MAY NOT BE REOUCEDAS LONG AS THE BOTTOMS WCHESOFT1E Se.T FENCE
ISMS BUREDAHDSECUREWATRENCHTIATSTABARESTHEFENCEANODOESNOTALLOWWATERTDBYPASSORUNOEWIJ E$LT
ENTRANCE. ORTHE INSTALLATION OFTHEWHEELWASR FWASHWG IS USED, ITSHALL BE DONNE ON AN AREA COVERED YlRH
CRUSHEDROCKANO WASHED WATER SHALL DRAIN TOASEOIhENTTRAP OR POND.
ALLOYANG I.IQVE3.tE3Tf OF WATER BETWEEN CEllS.11E DNOERSHALLBEAT LEAST ONE HALF OFTHE HEIGMOF THE RISERWWE-8A
2-T03FOOTM.GKERRASTRENGTHRL FPBRCSUPPORTEDBYTREATED4- ',MAYBEU DASADN®ERPLTERNATNE NAKED
1 tMIMENMCESTMDARg3
ANYSEDILIENTTHATISTRAC MDWOPAVEVEMBHALLBEREMOVEOILWEDATELYBYSWEEPING.THESEDIMEMCOLE DBY
SV1EEPINGSHALLBEREMOVEDOR$TABIUZEDGNSHE THE PAVEMENT SHALL NOT BE CLEANED BY WASHING DOWN THE STREET,
EXCEPTAAHEN SWEEMG IS INEEFECTNEANDTHERE ISATHREATTD PUBLIC SAFETY. IF IT NECESSARYTD WASH THE STREETS.A
STRAWBALESWRAFPEOYrtTH FILTERPNI-VAYBEUSEO
22 FTHEPD'm ISMORETNANSFEETDEEPADFFEREMMECH WMUSTBEPROPOSEO
23 TO PiDW DETERMNIhG SED'NMEMOEPTK ONEFOOT Ot1ERVAlS SFALLBE PFtOMBNENTLV MARKED ONIHE PLSER
11. ANY 04bAGESHNLBEREPAIRIMNEDA 1-
SMALL SUMP MUSTBE CONDUCTED. THESMthEW W' U DT MBEWMKMIWOTHESUYP%VHERERCANBECOMROLUDM'0
32 IFCONCEMMTEO FLDESAREECEVIDENT UPH:LLOD THE FENCE, IHEYMU3TBEIMERCEPTED AFm COYVEYEOTDASEOWEl1TTRAP OR P01dl.
J1 ITIS IMPORTANT TO CHECK THE UPKLL S DE OF THE FEIKE FOR SIGNS DF THE FENCE CLOGGNFL G AND ACTING AS A BARRIER TO OW AND
OISCHARGED APPROPRATELY.
34, ANY QUARRY SPALLS THAT ME LOOSENED FROM THE PAD AND END UP ON THE ROADWAY SHALL BE REMOVED IMJ.EDATELY
]. MNNIENAHCESTAHDARDS
RAC E
3.1. SEDU2EM SHALL BE REMIWED FROb1lHE POtm WTEN RREACIE5IFOOT WOFPIR
THE FUNDS
THEN CM.* CHANNEUUTION OF FLOWS PARALLEL TO THE FENCE. IF THIS OCCURS REPLACE THE FENCE OR REMOlEO THE TRAP
SEDMEM.
35, IF VEHICLES ARE ENTERING OR EXITING THE SITES AT POINTS OTHER THAN THE CONSTRUCTION ENTRANCES). FENCING SHALL BE
INSTALLED TD OONTROLTRAFFIC.
32 AMDANTS TO THE POND EN8OM
OR SLOPES REPLACED.
34. BEDMEM MOST BE REMOVED WHEN SEDWEM IS. INCHES KOH,
3E. IF THE FILTER FABNK: (GEOTEXTILE) HAS OETERKNATED INS TO tATRAVIOLET BREAKOOWII, IT SHALL BE REPLACED
PUDLIC WORKS
SILT FENCE®P
SILO. PLAN - 214.00
PURLIC R'oRKs
STABILIZE
8t'D. PLAN - 215.10
PUDLIC WORKS
S
SEDIMENT POND PLAN VIEW
BID. PLAN - 218.00
P®n YUDLIC WORKS
FILTER FABRIC PROTECTION
BID. PLAN - 216.20
)LARCH
MARCH 2O08
DEPARTMENT
DEPARTMENT
CONSTRUCTION ENTRANCE
DEPARTMENT
AND CROSS SECTIONS
DEPARTMENT
)LARCH 2O08
MARCH 2O08
2O08
1. BEFORE ANY CONSTRUCTION OR DEVELOPMENT ACTIVITY OCCURS, A PRECONSTRUCTION MEETING MUST
BE HELD WITH THE CiTY OF RENTON, PUBLIC WORKS DESIGN ENGINEER.
2. ALL LIMITS OF CLEARING AND AREAS OF VEGETATION PRESERVATION AS PRESCRIBED ON THE PLAN(S)
SHALL BE CLEARLY FLAGGED IN THE FIELD AND OBSERVED DURING CONSTRUCTION.
3. ALL REQUIRED SEDIMENTATION/EROSION CONTROL FACILITIES MUST BE CONSTRUCTED AND IN OPERATION
PRIOR TO LAND CLEARING AND/OR CONSTRUCTION TO ENSURE THAT SEDIMENT LADEN WATER DOES
NOT ENTER THE NATURAL DRAINAGE SYSTEM. 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 PERMTIEE.
4. 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.
5. 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, Ri STTRICTORS, CHANNELS, OR
RETENTION FACILITIES.
6. DURING THE TIME PERIOD OF OCTOBER 1ST THROUGH APRIL 30TH, ALL PROJECT DISTRIBUTED SOIL
AREAS GREATER THAN 5,ODD SQUARE FEET, THAT ARE TO BE LEFT UN -WORKED FOR MORE THAN 12
HOURS, SHALL BE COVERED BY MULCH, SODDING OR PLASTIC COVERING.
7. IN ANY AREA WHICH HAS BEEN STRIPPED OF VEGETATION AND WHERE NO FURTHER WORK IS
ANTICIPATED FOR A PERIOD 30 DAYS OR MORE, ALL DISTURBED AREAS MUST BE IMMEDIATELY
STABILIZED WiTH MULCHING, GRASS PLANTING OR OTHER APPROVED EROSION CONTROL TREATMENT
APPLICABLE TO THE TIME OF YEAR. GRASS SEEDING ALONE WILL BE ACCEPTABLE ONLY DURING THE
MONTHS OF APRIL THROUGH SEPTEMBER, INCLUSIVE. SEEDING MAY PROCEED, HOWEVER, WHENEVER iT
IS IN THE INTEREST OF THE PERMITEE, BUT MUST BE AUGMENTED WiTH MULCHING, NETTING OR
OTHER TREATMENT APPROVED 13Y THE CITY OF RENTON, OUTSIDE THE SPECIFIED TIME PERIOD.
B. FOR ALL EROSION/SEDIMENTATION CONTROL PONDS WHERE THE DEAD STORAGE DEPTH EXCEEDS 6
INCHES, A FENCE IS REQUIRED WITH A MINIMUM HEIGHT OF THREE (3) FEET, 3:1 SIDE SLOPES.
9. A TEMPORARY GRAVEL CONSTRUCTION ENTRANCE, 24 FEET X 50 FEET X B INCHES OF 4 TO 6 INCH
QUARRY SPALLS SHALL BE LOCATED AT ALL POINTS OF VEHICULAR INGRESS AND EGRESS TO THE
CONSTRUCTION SITE.
Pacific hg1rj L-yjIJJ
Design,
Civil 15nginaariny a
1 ' Planning Consuliani3
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NOTES
1. CDNDMONOFUSE
11. REQUWEDAT
11.1. THETOPOFALLSLOPESWDICEWDFMIVMDW M,O ETHAN20FEETOFVETRiC LIEF.
AT INTERVALS ON ANY SLOPES THAT EXCEEDS THE DIMENSIONS SPECIFIED BELLOW
AMMAGEStOPE ROPEPM FLOWPAIH U-TM
20H: LV 35M E 3W 0
BTD slap
nrOMHiv -
12TOn)H:1V 21- wf-
2 DESKINANDINSTALLADONSPECIFICADDNS
21, FMSLOPESSTEEPMR NZH:IVWITNMORETFANIOFEETDFVEMICALRELIEF,BENCHES)+AY BECONSTRUCTEDORCLDSER
SPACEDWTERCEPTORSWMESMAYBEUSEDTHEMREMEASUREMOSTBEDESIGNEDBYMENGWEMTOEFFEMT Y
I:TFACEPTTHEHIGHVELOCITYRUNOFFTDASE [tfE PONDORTRAP.
22. CONSTRUCTION9 R RCOVERTFAIPORARYSWALESSH MMWLMII D.
3, NAINTENANCESTANDARDS
3.1. DAVAGERESULTLWFRDMRUNOFFDRCONSMUCTIONACTMTYSHALLBEREPAIREDIMMEDAMY,
32 FTHE FACIL- DO NOT REGULARLY RETAIN STORM RUNOFF, THE CAPACITY MDIOR FREQUENCYCFTHE StVALES SHALL BE
INCREASED.
'4 /p/I-7
PUBLIC WORKS INTERCEPTOR SWALE ErrD' PLAN - 217.10
DEPARTMENT
)LARCH 2O08
NO. I REVISION I 13Y I DATE I APPR
5E AVD saEsr�TE�rnoI T
6 /Bar1oM � I
NOTES
1. CDNDMONDFUSE
11. WERECONCENTRATEDRUNOFFFROMDMSN EDMR TOMDFROMPONOSORTRAPS,
12 TO CONVEY RUNOFF INTEfiCEPTED FROM UNDiSTURBEDME/S MWNO THE SITE TGAI.DN-F1105NE DISCHARGE POINT.
2 WVNTENMCESTANDARDS
21, ANYSEDIAENTDEPDSMDNOFMORETHMO5FEETSHALLBEREMOVEDSDTHATTHECHMNELISRMMEDTDRSOWIHAL
DESIGN CAPACITY.
22. THE CHECK DAMS SHALL BE EXAMINED FOR SIGNS OF SOCURWG AND EROSION OF THE BED AND BANKS. IF SCOURING AND EROS
HA8 OCCURRED, AFFECTED AREAS SHALL BE PROTECTED BY RIPRAP DR AN EROSION CONTROL BLANKET
1. PRE -CONSTRUCTION MEETING.
2. POST SIGN PATH NAME AND PHONE NUMBER OF ESC SUPERVISOR (MAY BE CONSOLIDATED
NTH THE REQUIRED NDTICE OF CDNSTRUC71ON SIGN).
3. FLAG DR FENCE CLEARING LIMITS.
4. INSTALL CATCH BASIN PRDTEC71ON IF REQUIRED.
5. GRADE AND INSTALL CONSTRUCTION ENTRANCE(S).
6. INSTALL PERIMETER PROTECTION (SILT FENCE, BRUSH BARRIER, ETC.).
7. CONSTRUCT SEDIMENT PONDS AND TRAPS.
6. GRADE AND STABILIZE CONSTRUCTION ROADS.
9. CONSTRUCT SURFACE WATER CONTROLS (INTERCEPTOR DIKES, PIPE SLOPE DRAINS, ETC.)
SIMULTANEOUSLY PATH CLEARING AND GRADING FOR PROJECT DEVELOPMENT.
1D. MAINTAIN EROSION CONTROL MEASURES IN ACCORDANCE WITH APPENDIX D OF THE SURFACE
WATER DESIGN MANUAL AND MANUFACTURER'S RECOMMENDATIONS.
11. RELOCATE EROSIDN CONTROL MEASURES DR INSTALL NEW MEASURES SO THAT AS SITE
CONDITIONS CHANGE THE EROSION AND SEDIMENT CONTROL IS ALWAYS IN ACCORDANCE PATH
THE CITYS EROSION AND SEDIMENT CONTROL STANDARDS.
12. COVER ALL AREAS THAT VALL BE UNWORKED FOR MORE THAN SEVEN DAYS DURING THE DRY
SEASON OR TWO DAYS DURING THE WET SEASON WITH STRAW, WOOD FIBER MULCH, COMPOST,
PLASTIC SHEETING DR EQUIVALENT.
13. STABILIZE ALL AREAS THAT REACH FINAL GRADE WITHIN SEVEN DAYS.
14. SEED DR SOD ANY AREAS TO REMAIN UNWORKED FOR MORE THAN 3D DAYS
15. UPON COMPLE71DN OF THE PROJECT, ALL DISTURBED AREAS MUST BE STABILIZED AND BMPS
REMOVED IF APPROPRIATE
BY:
BY:
BY:
PUBLIC WORKS
DEPARTMENT
CHECK DAMS SPACING AND
CROSS SECTIONS
�• PI,Ati - 217.40
)LARCH 2O08
IFFIN
1•-20'
as ,�- CITY OF
RENTON
Plonning/Building/Public Works Cept.T
MPORARY
PPE'
RSWI'
ppER
auc AOOOCIISY
R-391007
APPROVED FOR CONSTRUCTION
SUBJECT TO ERRORS AND OMISSIONS
DATE:
DATE:
DATE:
DATE:
GRANT PLACE TOWNHOMES
EROSION AND SEDIMENT CONTROL NOTES AND
201B-12-
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Storm Water Pollution Prevention Plan for Construction Activities
NPDES STORM WATER PERMIT, AND
STATE WATER QUALITY STANDARDS
This project will disturbed more than 1 acres of land, NPDES Storm water permit is
required. Enhanced Basic water quality treatment is required per King County
Stormwater Management Manual which meets the requirements of State water quality
standards.
Pacific Engineering Design, LLC.
STATE OF WASHINGTON
DEPARTMENT OF ECOLOGY
PO Box 47600 • Olympia, WA 98504-7600 • 360-407-6000
711 for Washington Relay Service • Persons with a speech disability can call 877-833-6341
February 7, 2017
Satwant Singh
Apex Enterpises Group LLC
5218 70 Avenue Ct. W
University Place, WA 98467-4586
RE: Coverage under the Construction Stormwater General Permit
Permit number:
Site Name:
Location:
Disturbed Acres:
Dear Satwant Singh:
WAR304993
Grant Avenue Townhomes
1600 Grant Ave. S
Renton, WA County: King
1.77
The Washington State Department of Ecology (Ecology) received your Notice of Intent for coverage
under Ecology's Construction Stormwater General Permit (permit), This is your permit coverage
letter. Your permit coverage is effective on February 6, 2017. Please retain this permit coverage
letter with your permit (enclosed), stormwater pollution prevention plan (SWPPP), and site log
book, These materials are the official record of permit coverage for your site.
Please take time to read the entire permit and contact Ecology if you have any questions.
Appeal Process
You have a right to appeal coverage under the general permit to the Pollution Control Hearing Board
(PCHB) within 30 days of the date of receipt of this letter. This appeal is limited to the general
permit's applicability or non -applicability to a specific discharger. The appeal process is governed by
chapter 43.21B RCW and chapter 371-08 WAC. "Date of receipt" is defined in RCW 43.21B.001(2).
To appeal, you must do the following within 30 days of the date of receipt of this letter:
• File your appeal and a copy of the permit cover page with the PCHB (see addresses below).
Filing means actual receipt by the PCHB during regular business hours.
• Serve a copy of your appeal and the permit cover page on Ecology in paper form -
by mail or in person (see addresses below). E-mail is not accepted.
You must also comply with other applicable requirements in chapter 43.21 B RCW and
chapter 371-08 WAC.
;8 10
Satwant Singh
February 7, 2017
Page 2
Address and Location Information:
Street Addresses:
Department of Ecology
Attn: Appeals Processing Desk
300 Desmond Drive SE
Lacey, WA 98503
Pollution Control Hearings Board (PCHB)
I I l I Israel Road SW, Suite 301
Tumwater, WA 98501
Mailing Addresses:
Department of Ecology
Attn: Appeals Processing Desk
PO Box 47608
Olympia, WA 98504-7608
Pollution Control Hear4s Board
PO Box 40903
Olympia, WA 98504-0903
Electronic Discharge Monitoring Reports (WQWebDMR)
This permit requires that Permittees submit monthly discharge monitoring reports (DMRs) electronically
using Ecology's secure online system, WQWebDMR. To sign up for WQWebDMR go to:
www.ecy.wa.gov/programs/wq/permits/paris/webdmr.httni. If you have questions; contact the portal staff
at (360) 407-7097 (Olympia area), or (800) 633-6193/option 3, or email WQWebPortal@ecy.wa.gov.
Ecology Field Inspector Assistance
If you have questions regarding stormwater management at your construction site, please contact
Greg Stegman of Ecology's Northwest Regional Office in Bellevue at greg.stegmati@ecy.wa.gov or
(425) 649-7019.
Questions or Additional Information
Ecology is committed to providing assistance. Please review our web page at:
www.ecy.wa.gov/programs/wq/stonnwater/construction. If you have questions about the
construction stormwater general permit, please contact RaChelle Stane at rcla461 @ecy.wa.gov or
(360) 407-6556.
Sincerely,
Bill Moore, P.E., Manager
Program Development Services Section
Water Quality Program
Enclosure
Storm Water Pollution Prevention Plan for Construction Activities
STANDARDS AND SPECIFICATIONS
FOR SELECTED BMPs
Referance the 2005 WSDOE Manual for the following BMPs
1. Mark project clearing limits
BMP C101: Preserving Natural Vegetation
BMP C 103: Plastic or Metal Fence
BMP C104: Stake and Wire Fence
BMP C233: Silt Fence
2. Establishing the construction entrance(s)
BMP C105: Stabilized Construction Entrance
BMP C106: Wheel Wash
BMP C 107: Construction Road/Parking Area Stabilization
3. Storm water detention
Onsite Detention/wet vault to provide Level 2 (forest existing condition) Flow control
4. Selection and installation of sediment controls
BMP C200: Interceptor dike and swale
BMP C207: Check dams
BMP C233: Silt fence
BMP C241: Temporary sediment pond
BMP C250: Construction Storm water Chemical Treatment
5. Soil stabilization
BMP C120: Temporary and permanent seeding
BMP C 121: Mulching
BMP C 123: Plastic Covering
BMP C107: Construction Road/Parking Area Stabilization
6. Slope protection
BMP C120: Temporary and Permanent Seeding
BMP C121: Mulching
BMP C130: Surface Roughening
BMP C131: Gradient Terraces
Pacific Engineering Design, LLC.
Storm Water Pollution Prevention Plan for Construction Activities
BMP C200: Interceptor dike and swale
BMP C204: Pipe Slope Drains
BMP C207: Check dams
7. Drain inlet protection
BMP C220: Storm Drain Inlet Protection
8. Storm water outlet protection
BMP C220: Storm Drain Inlet Protection
Pacific Engineering Design, LLC.
Storm Water Pollution Prevention Plan for Construction Activities
APPENDIX C
MATERIAL SAFETY DATA SHEETS
Pacific Engineering Design, LLC.
Storm Water Pollution Prevention Plan for Construction Activities
Emergency Phone Numbers
Fire, Police, Ambulance
911
Owner: Ethiopian Muslim
Association of Seattle
(206) 420-2940
General Contractor
Office: Site
Mobile #
Subcontractors
Sub #1)
Office:
Sub #2
Sub #3
Sub #4
City or County Contact
Spill Hotline: (206) 973-4770 King County 24-hour dispatch: (206) 296-8100
Washington State Ecology Dept.
(360) 407-6000 (Olympia) (425) 649-7000 (Bellevue)
Pacific Engineering Design, LLC.
Storm Water Pollution Prevention Plan for Construction Activities
Spill Report Form
LOCATION:
II I (Date: Time: II
Regulatory agencies notified (date, time, person, agency, and how):
Material spilled:
Quantity
Source:
Extent of injuries (if
Adverse environmental impact (if
Immediate remedial actions taken at time of spill:
Measures taken or planned to prevent recurrence:
Additional
This report prepared by:
(Signature)
Pacific Engineering Design, LLC.
Storm Water Pollution Prevention Plan for Construction Activities
Storm water Monitoring Form
PROJECT:
CONTRACTOR:
RECEIVING WATER:
MONITOR PERFORMED BY:
Monitoring date: Time:
Current weather conditions:
Previous 24-hour weather conditions:
11 SAMPLING POINT I TURBIDITY (NTU) 11
Up -Stream
Adjacent
Downstream
Comments:
Sampler's Signature:
signature print name
Pacific Engineering Design, LLC.
Storm Water Pollution Prevention Plan for Construction Activities
Table 1
BMP Maintenance and Inspection Schedule
(Source Control BMPs)
The Development Company
Anywhere, USA
BMP
BMP Name
Recommended Maintenance
Recommended
Designation
Schedule of
Maintenance
C101
Preserving
Inspect flagged areas to make sure flagging
Daily
Natural
has not been removed. If tree roots have been
Vegetation
exposed or injured, recover and/or seal them.
C102
Buffer Zones
Inspect the area frequently to make sure
Daily
flagging remains in place and the area remains
undisturbed.
C 103
Plastic or
If the fence has been damaged or visibility
Daily
Metal Fence
reduced, it shall be repaired or replaced
immediately and visibility restored.
C104
Stake and
If the fence has been damaged or visibility
Daily
Wire Fence
reduced, it shall be repaired or replaced
immediately and visibility restored.
C105
Stabilized
Quarry spalls (or hog fuel) shall be added if
Daily
Construction
the pad is no longer in accordance with the
Entrance and
specifications. If the rock (or hog fuel)
Tire Wash
entrance is not working to keep streets clean,
then install wheel wash, sweep streets, or wash
streets if wash water can be collected.
C106
Wheel Wash
Wheel wash water shall not be discharged into
Daily
a storm drain or the site's storm water
collection system. Use closed -loop
recirculation, land application, or discharge to
sanitary sewer (by permit).
C107
Const. Road
Inspect stabilized areas regularly, especially
Daily
Stabilization
after large storm events. Add rock (hog fuel),
gravel, etc. as needed to maintain a stable
surface which won't erode.
C120
Temporary &
Re -seed areas failing to establish 80% cover
Inspect to ensure growth
Permanent
within one month (during growing season). If
weekly
Seeding
re -seeding is ineffective, use sodding or
nets/blankets. Eroded areas shall be corrected,
re -planted, and irrigated as required.
C121
Mulching
Maintain specified thickness of mulch cover.
Weekly and following
Eroded areas must be corrected and re-
storms
mulched. Drainage problems must be
corrected.
Pacific Engineering Design, LLC.
Storm Water Pollution Prevention Plan for Construction Activities
BMP
BMP Name
Recommended Maintenance
Recommended
Designation
Schedule of
Maintenance
C122
Nets and
Inspect to ensure good contact with ground
Weekly and following
Blankets
and no erosion of soils. Replace damaged
storms
material and re -staple where required. Correct
erosion problems immediately.
C123
Plastic
Replace torn sheets and repair open seams.
Weekly
Covering
Replace deteriorated plastic sheets. Dispose of
plastic when no longer needed.
C124
Sodding
If sod is unhealthy correct problem. If sod
Weekly and following
can't be established seed area and use net or
storms
blanket to stabilize soils.
C125
Top Soiling
Inspect stockpiles regularly, especially after
Weekly and following
large storm events. Stabilize areas that have
storms
eroded.
C126
Polyacrylami
Reapply PAM to actively worked soils at 48-
Daily
de
hr. intervals not to exceed 7 application per
Application
month. Reapply PAM to undisturbed soils at
2-month intervals.
C130
Surface
Seed roughened surfaces as soon as possible.
Weekly and following
Roughening
Re -grade and re -seed any areas beginning to
storms
erode.
C131
Gradient
Maintenance should be performed as needed.
Annually and following
Terraces
large storm events
C140
Dust Control
Re -apply dust control measures as necessary to
Daily during dry
keep dust to a minimum.
weather
Pacific Engineering Design, LLC.
Storm Water Pollution Prevention Plan for Construction Activities
Table 2
BMP Maintenance and Inspection Schedule
(Runoff, Conveyance, and Treatment BMPs)
The Development Company
Anywhere, USA
BMP
BMP Name
Recommended Maintenance
Recommended
Designation
Schedule of
Maintenance
C200
Interceptor
Inspect to insure structural integrity. Repair
Weekly and following
Dike & Swale
as needed
storms
C201
Grass -Lined
During growth period, inspect grass after
Weekly and following
Channels
rainstorms. Remove accumulated sediments.
storms
Inspect outlets to prevent scouring and
erosion.
C202
Riprap
Inspect to ensure underlain soils are not
Weekly and following
Channel
eroding. Inspect for slippage on slopes.
storms
Lining
C204
Pipe Slope
Check inlets for undercutting and outlets for
Weekly and following
Drains
erosion after rainstorms. Inspect pipe for
storms
damage. Check pipe for clogging debris.
C205
Subsurface
Check to ensure drains are not clogged with
Monthly
Drains
sediment or plant roots. Prevent heavy truck
traffic from crushing piping.
C206
Level Spreader
Check to ensure proper functioning after
Weekly and following
rainstorms. Prevent traffic from crossing the
storms
spreader. Repair if damaged.
C207
Check Dams
Remove sediment when one half the sump
Weekly and following
depth. Check for erosion around edges of
storms
dams.
C209
Outlet
Inspect and repair as needed. Add rock as
Weekly and following
Protection
needed. Clean energy dissipator if sediment
storms
builds up.
C220
Storm Drain
Replace clogged filter fabric. Clean sediment
Weekly and following
Inlet
from stone filters. Do not wash collected
storms
Protection
sediments into storm drains — remove to soil
stockpile.
C230
Straw Bale
Inspect daily during rainy periods. Check for
Daily during prolonged
Barrier
undercutting, end runs, and damaged bales.
rainy periods.
Remove accumulated sediment when one half
the barrier height.
C231
Brush Barrier
Inspect daily during rainy periods. Check for
Weekly and following
undercutting, end runs, and damaged sections.
storms
Remove accumulated sediment.
Pacific Engineering Design, LLC.
Storm Water Pollution Prevention Plan for Construction Activities
BMP
BMP Name
Recommended Maintenance
Recommended
Designation
Schedule of
Maintenance
C233
Silt Fence
Repair damaged fencing immediately.
Weekly and following
Intercept concentrated flows and reroute.
storms
Remove sediment accumulations at 6-inches.
Replace deteriorated fencing material.
Properly dispose of used fencing.
C234
Vegetated
Re -seed damaged areas immediately. Install
Weekly and following
Strip
sod to replace eroded vegetation. Reroute
storms
concentrated flows through vegetated strip
C240
Sediment Trap
Remove sediment when it reaches a depth of
Weekly and following
one foot. Repair damage to trap
storms
embankments and slopes.
C241
Sediment Pond
Remove sediment when it reaches a depth of
Weekly and following
one foot. Repair damage to pond
storms
embankments and slopes.
C250
Storm water
See Monitoring in Section 11
As required
Chemical
Treatment
Pacific Engineering Design, LLC.
Storm Water Pollution Prevention Plan for Construction Activities
Erosion and Sediment Control Inspection Form
Erosion Prevention
Inspector(s):
Site Name and Location:
Date:
Current Weather Conditions: Last 24 Hours:
BMP Designation
O.K
Not O.K.
BMP Condition, Corrective Action, General Notes
Construction Access
Trackout?
Street Clean?
Soil Stabilization
Signs of Erosion:
Gullies?
Slope Failures?
Rills?
Slope Protection
Plastic Condition?
Grass Growing?
Hydroseed Condition?
Matting?
Perimeter Control
Clearing Limits Marked?
Silt Fences?
Swales?
Conveyances Stable
Ditches?
Check Dams Intact?
Sand Bags?
Slope Drains?
TESC Management
Revisions Required?
Water Management
Infiltration System?
lean and Dirty Water Separated
Offsite Water Bypassing?
Outlet Protection
Stabilized?
Pacific Engineering Design, LLC.
Storm Water Pollution Prevention Plan for Construction Activities
Erosion and Sediment Control Inspection Form
Sediment Control
BMP Designation
O.K
Not O.K.
BMP Condition, Corrective Action, General Notes
Storm water Detention
And Monitoring
BMP Maintenance
Inlet Protection
Dust Control
Spill Prevention
ondition of Discharge
Water
Comments:
Pacific Engineering Design, LLC.
IX. Bond Quantities, Facility Summaries and
Declaration of Covenant
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d K
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
STORMWATER FACILITY SUMMARY SHEET DDES Permit
Number
(provide one Stormwater Facility Summary Sheet per Natural Discharge Location)
Overview:
Project Name
Grant Avenue Townhomes Date
Downstream Drainage Basins
Major Basin Name Black River
Immediate Basin Name
Flow Control:
Thunder Hills Creek
Flow Control FacilityName/Number Combined detention/wet vault /1
Facility
Location Near the west property line of the site
If none,
Flow control provided in regional/shared facility (give
location)
No flow control required Exemption number
General Facility Information:
Type/Number of detention facilities: Type/Number of infiltration facilities:
ponds ponds
1 vaults tanks
tanks trenches
Control Structure Location
At the northwest corner of the combined detention/wet vault
1-8" RISER W/1 ORIFICE AND SOLID TOP
Type of Control Structure 1— 1 2 n RTC W/2 ORTFTC'FS Number of Orifices/Restrictions
Size of Orifice/Restriction:
No. 2
No. 3
No. 4
No. I
1.25"
M
Flow Control Performance Standard Level 2 (forest existing condition)
2009 Surface Water Design Manual
1 /9/2009
1
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
Live Storage Volume
1.0
Number of Acres Served
28,800 cf. . Depth
2.11
Number of Lots 1
Dam Safety Regulations (Washington State Department of Ecology)
Reservoir Volume above natural grade N/A
Depth of Reservoir above natural grade N/A
Facility Summary Sheet Sketch
Volume Factor of Safety
All detention, infiltration and water quality facilities must include a detailed sketch.
01"x17" reduced size plan sheets may be used)
2009 Surface Water Design Manual 1/9/2009
2
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
Water Quality:
Type/Number of water quality facilitiesBMPs:
biofiltration swale
(regular/wet/ or continuous inflow)
large)
large)
above
combined detention/wetpond
sand filter (basic or large)
sand filter, linear (basic or
sand filter vault (basic or
(wetpond portion basic or large) sand bed depth (inches)
1 combined detention/wetvault stormwater wetland
filter strip 1 storm filter
flow dispersion wetpond (basic or large)
farm management plan
landscape management plan
oil/water separator
(baffle or coalescing plate)
Liner?
catch basin inserts:
Manufacturer
pre -settling pond
pre -settling structure:
Manufacturer
wetvault
Is facility Lined?
If so, what marker is used
high flow bypass structure (e.g., flow-splitter catch basin)
source controls
Design Information
Water Quality design flow 0.042 cfs (StormFilter manhole w/3 CSF cartridges)
Water Quality treated volume (sandfilter)
Water Quality storage volume (wetpool) 13 , 600 cf .
Facility Summary Sheet Sketch
2009 Surface Water Design Manual 1/9/2009
3
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
All detention, infiltration and water quality facilities must include a detailed sketch.
(11"x17" reduced size plan sheets may be used)
2009 Surface Water Design Manual 1/9/2009
4
RECORDING REQUESTED BY AND
WHEN RECORDED MAIL TO:
CITY CLERK'S OFFICE
CITY OF RENTON
1055 SOUTH GRADY WAY
RENTON WA 98057
DECLARATION OF COVENANT
FOR MAINTENANCE AND INSPECTION OF FLOW CONTROL BMPS
Grantor: vt pvAn � '51 r l't
Grantee: City of Renton
Legal Description:
Additional Legal(s) on: A V` ikC he A S '
Assessor's Tax Parcel ID#: 2-0 Z-305
IN CONSIDERATION of the approved City of Renton(check one of the following) ❑ residential
building permit, ZI commercial building permit,14 clearing and grading permit, ❑ subdivision permit, or
❑ short subdivision permit for Application File N LU SWP 1•5-000 8g relating to the
real property ("Property") described above, the Grantor(s), the owner(s) in fee of that Property, hereby
covenants(covenant) with City or Renton, a political subdivision of the state of Washington, that
he/she(they) will observe, consent to, and abide by the conditions and obligations set forth and described
in Paragraphs 1 through 8 below with regard to the Property. Grantor(s) hereby grants(grant),
covenants(covenant), and agrees(agree) as follows:
1. Grantor(s) or his/her(their) successors in interest and assigns ("Owners") shall retain, uphold,
and protect the stormwater management devices, features, pathways, limits, and restrictions, known as
flow control best management practices ("BMPs"), shown on the approved Flow Control BMP Site Plan
for the Property attached hereto and incorporated herein as Exhibit A.
2. The Owners shall at their own cost, operate, maintain, and keep in good repair, the Property's
BMPs as described in the approved Design and Maintenance Details for each BMP attached hereto and
incorporated herein as Exhibit B.
3. City or Renton shall provide at least 30 days written notice to the Owners that entry on the
Property is planned for the inspection of the BMPs. After the 30 days, the Owners shall allow the City of
Renton to enter for the sole purpose of inspecting the BMPs. In lieu of inspection by the City, the
Owners may elect to engage a licensed civil engineer registered in the state of Washington who has
expertise in drainage to inspect the BMPs and provide a written report describing their condition. If the
engineer option is chosen, the Owners shall provide written notice to the City of Renton within fifteen
days of receiving the City's notice of inspection. Within 30 days of giving this notice, the Owners, or the
engineer on behalf of the Owners, shall provide the engineer's report to the City of Renton. If the report
is not provided in a timely manner as specified above, the City of Renton may inspect the BMPs without
further notice.
4. If the City determines from its inspection, or from an engineer's report provided in accordance
with Paragraph 3, that maintenance, repair, restoration, and/or mitigation work is required for the BMPs,
The City shall notify the Owners of the specific maintenance, repair, restoration, and/or mitigation work
(Work) required under RMC 4-6-030. The City shall also set a reasonable deadline for completing the
Work or providing an engineer's report that verifies completion of the Work. After the deadline has
passed, the Owners shall allow the City access to re -inspect the BMPs unless an engineer's report has
been provided verifying completion of the Work. If the work is not completed properly within the time
frame set by the City, the City may initiate an enforcement action. Failure to properly maintain the BMPs
is a violation of RMC 4-6-030 and may subject the Owners to enforcement under the RMC 1-3, including
fines and penalties.
5. Apart from performing routine landscape maintenance, the Owners are hereby required to
obtain written approval from the City or Renton before performing any alterations or modifications to the
6. Any notice or approval required to be given by one party to the other under the provisions of
this Declaration of Covenant shall be effective upon personal delivery to the other party, or after three (3)
days from the date that the notice or approval is mailed with delivery confirmation to the current address
on record with each Party. The parties shall notify each other of any change to their addresses.
7. This Declaration of Covenant is intended to promote the efficient and effective management of
surface water drainage on the Property, and it shall inure to the benefit of all the citizens of the City of
Renton and its successors and assigns. This Declaration of Covenant shall run with the land and be
binding upon Grantor(s), and Grantor's(s') successors in interest and assigns.
8. This Declaration of Covenant may be terminated by execution of a written agreement by the
Owners and the City of Renton that is recorded by King County in its real property records.
IN WITNESS WHEREOF, this Declaration of Covenant for the Maintenance and Inspection of
Flow Control BMPs is executed this day of , 20
GRANTOR, owner of the Property
GRANTOR, owner of the Property
STATE OF WASHINGTON )
COUNTY OF KING )ss.
On this day personally appeared before me:
, to me known to be the individual(s) described in
and who executed the within and foregoing instrument and acknowledged that they signed the same as
their flee and voluntary act and deed, for the uses and purposes therein stated.
Given under my hand and official seal this day of , 20
Printed name
Notary Public in and for the State of Washington,
residing at
My appointment expires
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C.2.10 NATIVE GROWTH RETENTION CREDIT
c) Any portion of the area credited as mitigated that is pollution -generating impervious surface
must be less than 5,000 square feet on any one site unless the surface is served by a water quality
treatment facility designed by a civil engineer in accordance with Section 1.2.8 of the SWDM.
C.2.10.2 EXAMPLE SIZING CALCULATION
Area of target impervious surface to be credited as mitigated: 500 square feet
Donor area of native vegetated surface that must be preserved: 500 x 3.5 = 1,750 square feet
C.2.10.3 MAINTENANCE INSTRUCTIONS
If the native growth retention credit flow control BMP is proposed for a project, the following
maintenance and operation instructions must be recorded as an attachment to the required declaration of
covenant and grant of easement per Requirement 3 of Section C.1.3.3 (p. C-18). The intent of these
instructions is to explain to future property owners, the purpose of the BMP and how it must be
maintained and operated. These instructions are intended to be a minimum; DDES may require additional
instructions based on site -specific conditions. Also, as the County gains more experience with the
maintenance and operation of these BMPs, future updates to the instructions will be posted on King
County's Sinface Water Design Manual website.
TEXT OF INSTRUCTIONS
Your property contains a stormwater management flow control BMP (best management practice) known as
"native growth retention," the practice of preserving a portion of a property in a native vegetated condition
(e.g., forest) so as to minimize increases in stormwater runoff from clearing and to offset the stormwater
runoff impacts caused by impervious surfaces on your property. This native vegetated area on your
property was set aside by covenant as "native growth retention area."
The "native growth retention area" is delineated on the flow control BMP site plan attached to the covenant.
The trees, vegetation, ground cover, and soil conditions in this area may not be disturbed, except as
allowed by the following provisions:
1. Trees may be harvested in accordance with a King County -approved forest management plan.
2. Individual trees that have a structural defect due to disease or other defects, and which threaten to
damage a structure, road, parking area, utility, or place of employment or public assembly, or block
emergency access, may be topped, pruned, or removed as needed to eliminate the threat.
3. Dead or fallen trees, tree limbs within ten feet of the ground, and branches overhanging a residence
may be removed to reduce the danger of wildfire.
4. Noxious weeds (i.e., plant species listed on the State noxious weed list in Chapter 16-750 WAC) and
invasive vegetation (i.e., plant species listed as obnoxious weeds on the noxious weed list adopted by
the King County Department of Natural Resources and Parks) may be removed.
5. Passive recreation uses and related facilities, including pedestrian, equestrian community and bicycle
trails, nature viewing areas, fishing and camping areas, and other similar uses that do not require
permanent structures, are allowed if clearing and soil compaction associated with these uses and
facilities does not exceed eight percent of the native growth retention area.
2009 Surface Water Design Manual — Appendix C 1/9/2009
C-79
SECTION C.2 FLOW CONTROL BMPs
Design Specifications
A minimum of 6 inches of free draining base material (sand or gravel) is required under the modular
grid material.
2. The modular grid material must be installed according to the manufacturer's instructions.
3. The surface area of the modular grid openings must be at least 50% of the total surface area of the
modular grid pavement.
4. The modular grid openings must be filled with gravel, sand, or a mixture of both.
5. Smooth surface walkways may be run across modular grid pavements, provided the impervious
surfaced walkways do not exceed 10 percent of the total pavement surface.
C.2.6.6 GRASSED MODULAR GRID PAVEMENT
Grassed modular grid pavement is basically a modular grid pavement with grass planted in the openings
or in a thin layer of soil over the grid material. The benefits of this measure are reduced runoff peaks and
volumes resulting from the increased infiltration of stormwater, the increased water storage provided in
the grid soil and base, and the increased evapotranspiration provided by the grass. The grassed surface
also helps remove pollutants that are left behind by vehicles.
Uses: Low -traffic or infrequently used areas such as low -traffic driveways, overflow parking, event
parking, church parking, employee parking, maintenance access roads, etc.; they are not allowed
in King County road right-of-way.
Design Specifications
1. A minimum of 6 inches of free draining base material (sand or gravel) is required under the modular
grid material.
2. The modular grid material must be installed according to the manufacturer's instructions.
3. The surface area of the modular grid openings must be at least 50% of the total surface area of the
modular grid pavement.
4. The modular grid openings must be filled with a sandy soil mix suitable for growing grass as specified
by the manufacturer's instructions or a landscape architect.
5. Smooth surface walkways may be run across modular grid pavements, provided the impervious
surfaced walkways do not exceed 10 percent of the total pavement area.
C.2.6.7 MAINTENANCE INSTRUCTIONS FOR PERMEABLE PAVEMENT
If the permeable pavement flow control BMP is proposed for a project, the following maintenance and
operation instructions, plus any provided by the manufacturer or installer, must be recorded as an
attachment to the required declaration of covenant and grant of easement per Requirement 3 of Section
C.1.3.3 (p. C-18). The intent of these instructions is to explain to future property owners, the purpose of
the BMP and how it must be maintained and operated. These instructions are intended to be a minimum;
DDES may require additional instructions based on site -specific conditions or manufacturer's
recommendations. Also, as the County gains more experience with the maintenance and operation of
these BMPs, future updates to these instructions will be posted on King County's Sznface Water Design
Manual website.
i TEXT OF INSTRUCTIONS FOR NON -VEGETATED PERMEABLE PAVEMENT
Your property contains a stormwater management flow control BMP (best management practice) called
"permeable pavement," which was installed to minimize the stormwater quantity and quality impacts of
1/9/2009 L_ 119 i ' ,'7.� f ' 2009 Surface Water Design Manual — Appendix C
C-66
C.2.6 PERMEABLE PAVEMENT
some or all of the paved surfaces on your property. Permeable pavements reduce the amount of rainfall
that becomes runoff by allowing water to seep through the pavement into a free -draining gravel or sand
bed, where it can be infiltrated into the ground.
The type(s) of permeable pavement used on your property is: ❑ porous concrete, ❑ porous asphaltic
concrete, ❑ permeable pavers, ❑ modular grid pavement.
The area covered by permeable pavement as depicted by the flow control BMP site plan and design details
must be maintained as permeable pavement and may not be changed without written approval either from
the King County Water and Land Resources Division or through a future development permit from King
County.
Permeable pavements must be inspected after one major storm each year to make sure it is working
properly. Prolonged ponding or standing water on the pavement surface is a sign that the system is
defective and may need to be replaced. If this occurs, contact the pavement installer or the King County
Water and Land Resources Division for further instructions. A typical permeable pavement system has a
life expectancy of approximately 25-years. To help extend the useful life of the system, the surface of the
permeable pavement should be kept clean and free of leaves, debris, and sediment through regular
sweeping or vacuum sweeping. The owner is responsible for the repair of all ruts, deformation, and/or
broken paving units.
P TEXT OF INSTRUCTIONS FOR VEGETATED PERMEABLE PAVEMENT
Your property contains a stormwater management flow control BMP (best management practice) called
"grassed modular grid pavement," which was installed to minimize the stormwater quantity and quality
impacts of some or all of the paved surfaces on your property. Grassed modular grid pavement has the
runoff characteristics of a lawn while providing the weight -bearing capacity of concrete pavement. The
grassed surface not only minimizes runoff quantity, it helps to filter pollutants generating by vehicular use
of the surface.
The composition and area of grassed modular grid pavement as depicted by the flow control BMP site plan
and design details must be maintained and may not be changed without written approval either from the
King County Water and Land Resources Division or through a future development permit from King
County.
Grassed modular grid pavement must be inspected after one major storm each year to make sure it is
working properly. Prolonged ponding or standing water on the pavement surface is a sign that the system
defective and may need to be replaced. If this occurs, contact the pavement installer or the King County
Water and Land Resources Division for further instructions. The grassed surface of the pavement must be
regularly mowed and maintained in a good condition. Bare spots must be replanted in the spring or fall.
�Xi� i i I l;
A
2009 Surface Water Design Manual — Appendix C 1/9/2009
C-67
RECORDING REQUESTED BY AND
WHEN RECORDED MAIL TO:
CITY CLERK'S OFFICE
CITY OR RENTON
1055 SOUTH GRADY WAY
RENTON WA 98057
DECLARATION OF COVENANT
FOR INSPECTION AND MAINTENANCE OF STORMWATER
FACILITIES AND BMPS
Grantor: G7/ 11✓�'V1�U ► �� 1
Grantee: City or Renton
Legal Description:
Additional Legal(s) on:
Assessor's Tax Parcel ID#: Z-0 2-; p — ! 05
IN CONSIDERATION of the approved City or Renton (S(r ., yA & S-An no�,&_ permit
for application file No LU SWP )5-0019&-55 relating to the real property ("Property")
described above, the Grantor(s), the owner(s) in fee of that Property, hereby covenants(covenant) with
the City or Renton, a political subdivision of the state of Washington, that he/she(they) will
observe, consent to, and abide by the conditions and obligations set forth and described in Paragraphs 1
through 10 below with regard to the Property, and hereby grants(grant) an easement as described in
Paragraphs 2 and 3. Grantor(s) hereby grants(grant), covenants(covenant), and agrees(agree) as follows:
1. The Grantor(s) or his/her(their) successors in interest and assigns ("Owners") shall at their
own cost, operate, maintain, and keep in good repair, the Property's stormwater facilities and best
management practices ("BMPs") identified in the plans and specifications submitted to City of Renton
for the review and approval of permit(s) #: L.A I,5 -MAK5' . Stormwater facilities
include pipes, swales, tanks, vaults, ponds, and other engineered structures designed to manage
stormwater on the Property. Stormwater BMPs include dispersion and infiltration devices, native
vegetated areas, permeable pavements, vegetated roofs, rainwater harvesting systems, reduced
impervious surface coverage, and other measures designed to reduce the amount of stormwater runoff on
the Property.
2. City or Renton shall have the right to ingress and egress over those portions of the Property
necessary to perform inspections of the stormwater facilities and BMPs and conduct other activities
specified in this Declaration of Covenant and in accordance with RMS 4-6-030. This right of ingress and
egress, right to inspect, and right to perform required maintenance or repair as provided for in Section 3
below, shall not extend over those portions of the Property shown in Exhibit "A."
3. If City of Renton determines that maintenance or repair work is required to be done to any of
the stormwater facilities or BMPs, City of Renton shall give notice of the specific maintenance and/or
repair work required pursuant to RMC 4-6-030. The City shall also set a reasonable time in which such
work is to be completed by the Owners. If the above required maintenance or repair is not completed
within the time set by the City, the City may perform the required maintenance or repair, and hereby is
given access to the Property, subject to the exclusion in Paragraph 2 above, for such purposes. Written
notice will be sent to the Owners stating the City's intention to perform such work. This work will not
commence until at least seven (7) days after such notice is mailed. If, within the sole discretion of the
City, there exists an imminent or present danger, the seven (7) day notice period will be waived and
maintenance and/or repair work will begin immediately.
4. If at any time the City of Renton reasonably determines that a stormwater facility or BMP on
the Property creates any of the hazardous conditions listed in KCC 9.04.130 or relevant municipal
successor's codes as applicable and herein incorporated by reference, The City may take measures
specified therein.
5. The Owners shall assume all responsibility for the cost of any maintenance or repair work
completed by the City as described in Paragraph 3 or any measures taken by the City to address
hazardous conditions as described in Paragraph 4. Such responsibility shall include reimbursement to the
City within thirty (30) days of the receipt of the invoice for any such work performed. Overdue
payments will require payment of interest at the current legal rate as liquidated damages. If legal action
ensues, the prevailing party is entitled to costs or fees.
6. The Owners are hereby required to obtain written approval fiom City of Renton prior to
filling, piping, cutting, or removing vegetation (except in routine landscape maintenance) in open
vegetated stormwater facilities (such as swales, channels, ditches, ponds, etc.), or performing any
alterations or modifications to the stormwater facilities and BMPs referenced in this Declaration of
Covenant.
7. Any notice or consent required to be given or otherwise provided for by the provisions of this
Agreement shall be effective upon personal delivery, or three (3) days after mailing by Certified Mail,
return receipt requested.
8. With regard to the matters addressed herein, this agreement constitutes the entire agreement
between the parties, and supersedes all prior discussions, negotiations, and all agreements whatsoever
whether oral or written.
9. This Declaration of Covenant is intended to protect the value and desirability of the real
property described above, and shall inure to the benefit of all the citizens of the City of Renton and its
successors and assigns. This Declaration of Covenant shall run with the land and be binding upon
Grantor(s), and Grantor's(s') successors in interest, and assigns.
10. This Declaration of Covenant may be terminated by execution of a written agreement by the
Owners and the City that is recorded by King County in its real property records.IN WITNESS
WHEREOF, this Declaration of Covenant for the Inspection and Maintenance of Stormwater Facilities
and BMPs is executed this day of , 20
GRANTOR, owner of the Property
GRANTOR, owner of the Property
STATE OF WASHINGTON )
COUNTY OF KING )ss.
On this day personally appeared before me:
, to me known to be the individual(s) described in
and who executed the within and foregoing instrument and acknowledged that they signed the same as
their free and voluntary act and deed, for the uses and purposes therein stated.
Given under my hand and official seal this day of , 20
Printed name
Notary Public in and for the State of Washington,
residing at
My appointment expires
QI N
m
=Q
X
WV
X. Operations and Maintenance Manual
The onsite storm facilities will be maintained by the property owner and manager
53
KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL
APPENDIX A
MAINTENANCE REQUIREMENTS FOR FLOW
CONTROL, CONVEYANCE, AND WQ FACILITIES
This appendix contains the maintenance requirements for the following typical stormwater control
facilities and components:
No. 1 — Detention Ponds (p. A-2)
No. 2 — Infiltration Facilities (p. A-3)
No. 3 — Detention Tanks and Vaults (p. A-5)
No. 4 — Control Structure/Flow Restrictor (p. A-7)
No. 5 — Catch Basins and Manholes (p. A-9)
No. 6 — Conveyance Pipes and Ditches (p. A-11)
No. 7 — Debris Barriers (e.g., Trash Racks) (p. A-12)
No. 8 — Energy Dissipaters (p. A- 13)
No. 9 —Fencing (p. A-14)
No. 10 — Gates/Bollards/Access Barriers (p. A-15)
No. 11 —Grounds (Landscaping) (p. A-16)
No. 12 — Access Roads (p. A-17)
No. 13 — Basic Biofiltration Swale (grass) (p. A-18)
No. 14 — Wet Biofiltration Swale (p. A-19)
No. 15 — Filter Strip (p. A-20)
No. 16 — Wetpond (p. A-21)
No. 17 — Wetvault (p. A-23)
No. 18 — Stormwater Wetland (p. A-24)
No. 19 — Sand Filter Pond (p. A-26)
No. 20 — Sand Filter Vault (p. A-28)
No. 21— Stormfilter (Cartridge Type) (p. A-30)
No. 22 — Baffle Oil/Water Separator (p. A-32)
No. 23 — Coalescing Plate Oil/Water Separator (p. A-33)
No. 24 — Catch Basin Insert (p. A-35)
2009 Surface Water Design Manual — Appendix A 1/9/2009
A-1
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO. 3 - DETENTION TANKS AND VAULTS
Maintenance
Defect or Problem
Conditions When Maintenance is Needed
Results Expected When
Component
Maintenance is Performed
Site
Trash and debris
Any trash and debris which exceed 1 cubic foot
Trash and debris cleared from site.
per 1,000 square feet (this is about equal to the
amount of trash it would take to fill up one
standard size office garbage can). In general,
there should be no visual evidence of dumping.
Noxious weeds
Any noxious or nuisance vegetation which may
Noxious and nuisance vegetation
constitute a hazard to County personnel or the
removed according to applicable
public.
regulations. No danger of noxious
vegetation where County personnel
or the public might normally be.
Contaminants and
Any evidence of contaminants or pollution such
Materials removed and disposed of
pollution
as oil, gasoline, concrete slurries or paint.
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Grass/groundcover
Grass or groundcover exceeds 18 inches in
Grass or groundcover mowed to a
height.
height no greater than 6 inches.
Tank or Vault
Trash and debris
Any trash and debris accumulated in vault or tank
No trash or debris in vault.
Storage Area
(includes floatables and non-floatables).
Sediment
Accumulated sediment depth exceeds 10% of the
All sediment removed from storage
accumulation
diameter of the storage area for length of
area.
storage vault or any point depth exceeds 15% of
diameter. Example: 72-inch storage tank would
require cleaning when sediment reaches depth of
7 inches for more than %2 length of tank.
Tank Structure
Plugged air vent
Any blockage of the vent.
Tank or vault freely vents.
Tank bent out of
Any part of tank/pipe is bent out of shape more
Tank repaired or replaced to design.
shape
than 10% of its design shape.
Gaps between
A gap wider than'% -inch at the joint of any tank
No water or soil entering tank
sections, damaged
sections or any evidence of soil particles entering
through joints or walls.
joints or cracks or
the tank at a joint or through a wall.
tears in wall
Vault Structure
Damage to wall,
Cracks wider than %-inch, any evidence of soil
Vault is sealed and structurally
frame, bottom, and/or
entering the structure through cracks or qualified
sound.
top slab
inspection personnel determines that the vault is
not structurally sound.
Inlet/Outlet Pipes
Sediment
Sediment filling 20% or more of the pipe.
Inlet/outlet pipes clear of sediment.
accumulation
Trash and debris
Trash and debris accumulated in inlet/outlet
No trash or debris in pipes.
pipes (includes floatables and non-floatables).
Damaged
Cracks wider than'% -inch at the joint of the
No cracks more than'/< -inch wide at
inlet/outlet pipes or any evidence of soil entering
the joint of the inlet/outlet pipe.
at the joints of the inlet/outlet pipes.
2009 Surface Water Design Manual — Appendix A 1/9/2009
A-5
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO.3 - DETENTION TANKS AND VAULTS
Maintenance
Defect or Problem
Conditions When Maintenance is Needed
Results Expected When
Component
Maintenance is Performed
Access Manhole
Cover/lid not in place
Cover/lid is missing or only partially in place.
Manhole access covered.
Any open manhole requires immediate
maintenance.
Locking mechanism
Mechanism cannot be opened by one
Mechanism opens with proper tools.
not working
maintenance person with proper tools. Bolts
cannot be seated. Self-locking cover/lid does not
work.
Cover/lid difficult to
One maintenance person cannot remove
Cover/lid can be removed and
remove
cover/lid after applying 80 Ibs of lift.
reinstalled by one maintenance
person.
Ladder rungs unsafe
Missing rungs, misalignment, rust, or cracks.
Ladder meets design standards.
Allows maintenance person safe
access.
Large access
Damaged or difficult
Large access doors or plates cannot be
Replace or repair access door so it
doors/plate
to open
opened/removed using normal equipment.
can opened as designed.
Gaps, doesn't cover
Large access doors not flat and/or access
Doors close flat and covers access
completely
opening not completely covered.
opening completely.
Lifting Rings missing,
Lifting rings not capable of lifting weight of door
Lifting rings sufficient to lift or
rusted
or plate.
remove door or plate.
1/9/2009 2009 Surface Water Design Manual — Appendix A
A-6
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO.4 - CONTROL STRUCTURE/FLOW RESTRICTOR
Maintenance
Defect or Problem
Condition When Maintenance is Needed
Results Expected When
Component
Maintenance is Performed
Structure
Trash and debris
Trash or debris of more than cubic foot which
No Trash or debris blocking or
is located immediately in front of the structure
potentially blocking entrance to
opening or is blocking capacity of the structure by
structure.
more than 10%.
Trash or debris in the structure that exceeds 1/3
No trash or debris in the structure.
the depth from the bottom of basin to invert the
lowest pipe into or out of the basin.
Deposits of garbage exceeding 1 cubic foot in
No condition present which would
volume.
attract or support the breeding of
insects or rodents.
Sediment
Sediment exceeds 60% of the depth from the
Sump of structure contains no
bottom of the structure to the invert of the lowest
sediment.
pipe into or out of the structure or the bottom of
the FROP-T section or is within 6 inches of the
invert of the lowest pipe into or out of the
structure or the bottom of the FROP-T section.
Damage to frame
Corner of frame extends more than 1/4 inch past
Frame is even with curb.
and/or top slab
curb face into the street (If applicable).
Top slab has holes larger than 2 square inches or
Top slab is free of holes and cracks.
cracks wider than '/< inch.
Frame not sitting flush on top slab, i.e.,
Frame is sitting flush on top slab.
separation of more than % inch of the frame from
the top slab.
Cracks in walls or
Cracks wider than'/. inch and longer than 3 feet,
Structure is sealed and structurally
bottom
any evidence of soil particles entering structure
sound.
through cracks, or maintenance person judges
that structure is unsound.
Cracks wider than inch and longerthan 1 foot
No cracks more than'/4 inch wide at
at the joint of any inlet/outlet pipe or any evidence
the joint of inlet/outlet pipe.
of soil particles entering structure through cracks.
Settlement/
Structure has settled more than 1 inch or has
Basin replaced or repaired to design
misalignment
rotated more than 2 inches out of alignment.
standards.
Damaged pipe joints
Cracks wider than'/. -inch at the joint of the
No cracks more than wide at
inlet/outlet pipes or any evidence of soil entering
the joint of inlet/outlet pipes.
the structure at the joint of the inlet/outlet pipes.
Contaminants and
Any evidence of contaminants or pollution such
Materials removed and disposed of
pollution
as oil, gasoline, concrete slurries or paint.
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Ladder rungs missing
Ladder is unsafe due to missing rungs,
Ladder meets design standards and
or unsafe
misalignment, rust, cracks, or sharp edges.
allows maintenance person safe
access.
FROP-T Section
Damage
T section is not securely attached to structure
T section securely attached to wall
wall and outlet pipe structure should support at
and outlet pipe.
least 1,000 Ibs of up or down pressure.
Structure is not in upright position (allow up to
Structure in correct position.
10% from plumb).
Connections to outlet pipe are not watertight or
Connections to outlet pipe are water
show signs of deteriorated grout.
tight; structure repaired or replaced
and works as designed.
Any holes —other than designed holes —in the
Structure has no holes other than
structure.
designed holes.
Cleanout Gate
Damaged or missing
Cleanout gate is missing.
Replace cleanout gate.
2009 Surface Water Design Manual — Appendix A 1/9/2009
A-7
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO.4 - CONTROL STRUCTURE/FLOW RESTRICTOR
Maintenance
Defect or Problem
Condition When Maintenance is Needed
Results Expected When
Component
Maintenance is Performed
Cleanout gate is not watertight.
Gate is watertight and works as
designed.
Gate cannot be moved up and down by one
Gate moves up and down easily and
maintenance person.
is watertight.
Chain/rod leading to gate is missing or damaged.
Chain is in place and works as
designed.
Orifice Plate
Damaged or missing
Control device is not working properly due to
Plate is in place and works as
missing, out of place, or bent orifice plate.
designed.
Obstructions
Any trash, debris, sediment, or vegetation
Plate is free of all obstructions and
blocking the plate.
works as designed.
Overflow Pipe
Obstructions
Any trash or debris blocking (or having the
Pipe is free of all obstructions and
potential of blocking) the overflow pipe.
works as designed.
Deformed or damaged
Lip of overflow pipe is bent or deformed.
Overflow pipe does not allow
lip
overflow at an elevation lower than
design
Inlet/Outlet Pipe
Sediment
Sediment filling 20% or more of the pipe.
Inlet/outlet pipes clear of sediment.
accumulation
Trash and debris
Trash and debris accumulated in inlet/outlet
No trash or debris in pipes.
pipes (includes floatables and non-floatables).
Damaged
Cracks wider than''/2-inch at the joint of the
No cracks more than 1/4-inch wide at
inlet/outlet pipes or any evidence of soil entering
the joint of the inlet/outlet pipe.
at the joints of the inlet/outlet pipes.
Metal Grates
Unsafe grate opening
Grate with opening wider than 7/8inch.
Grate opening meets design
(If Applicable)
standards.
Trash and debris
Trash and debris that is blocking more than 20%
Grate free of trash and debris.
of grate surface.
footnote to guidelines for disposal
Damaged or missing
Grate missing or broken member(s) of the grate.
Grate is in place and meets design
standards.
Manhole Cover/Lid
Cover/lid not in place
Cover/lid is missing or only partially in place.
Cover/lid protects opening to
Any open structure requires urgent
structure.
maintenance.
Locking mechanism
Mechanism cannot be opened by one
Mechanism opens with proper tools.
Not Working
maintenance person with proper tools. Bolts
cannot be seated. Self-locking cover/lid does not
work.
Cover/lid difficult to
One maintenance person cannot remove
Cover/lid can be removed and
Remove
cover/lid after applying 80 lbs. of lift.
reinstalled by one maintenance
person.
1/9/2009 2009 Surface Water Design Manual — Appendix A
A-8
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO.5 - CATCH BASINS AND MANHOLES
Maintenance
Defect or Problem
Condition When Maintenance is Needed
Results Expected When
Component
Maintenance is Performed
Structure
Sediment
Sediment exceeds 60% of the depth from the
Sump of catch basin contains no
bottom of the catch basin to the invert of the
sediment.
lowest pipe into or out of the catch basin or is
within 6 inches of the invert of the lowest pipe
into or out of the catch basin.
Trash and debris
Trash or debris of more than % cubic foot which
No Trash or debris blocking or
is located immediately in front of the catch basin
potentially blocking entrance to
opening or is blocking capacity of the catch basin
catch basin.
by more than 10%.
Trash or debris in the catch basin that exceeds
No trash or debris in the catch basin.
'/s the depth from the bottom of basin to invert the
lowest pipe into or out of the basin.
Dead animals or vegetation that could generate
No dead animals or vegetation
odors that could cause complaints or dangerous
present within catch basin.
gases (e.g., methane).
Deposits of garbage exceeding 1 cubic foot in
No condition present which would
volume,
attract or support the breeding of
insects or rodents.
Damage to frame
Corner of frame extends more than 3% inch past
Frame is even with curb.
and/or top slab
curb face into the street (If applicable).
Top slab has holes larger than 2 square inches or
Top slab is free of holes and cracks.
cracks wider than % inch.
Frame not sitting flush on top slab, i.e.,
Frame is sitting flush on top slab.
separation of more than % inch of the frame from
the top slab.
Cracks in walls or
bottom
Cracks wider than '% inch and longer than 3 feet,
any evidence of soil particles entering catch
Catch basin is sealed and
structurally sound.
basin through cracks, or maintenance person
judges that catch basin is unsound.
Cracks wider than Yz inch and longer than 1 foot
No cracks more than inch wide at
at the joint of any inlettoutlet pipe or any evidence
the joint of inlet/outlet pipe.
of soil particles entering catch basin through
cracks.
Settlement/
Catch basin has settled more than 1 inch or has
Basin replaced or repaired to design
misalignment
rotated more than 2 inches out of alignment.
standards.
Damaged pipe joints
Cracks wider than '%-inch at the joint of the
No cracks more than 1/4-inch wide at
inlettoutlet pipes or any evidence of soil entering
the joint of inlettoutlet pipes.
the catch basin at the joint of the inlet/outlet
pipes.
Contaminants and
Any evidence of contaminants or pollution such
Materials removed and disposed of
pollution
as oil, gasoline, concrete slurries or paint.
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Inlet/Outlet Pipe
Sediment
Sediment filling 20% or more of the pipe.
Inlettoutlet pipes clear of sediment.
accumulation
Trash and debris
Trash and debris accumulated in inlettoutlet
No trash or debris in pipes.
pipes (includes floatables and non-floatables).
Damaged
Cracks wider than YZ-inch at the joint of the
No cracks more than wide at
inlettoutlet pipes or any evidence of soil entering
the joint of the inlettoutlet pipe.
at the joints of the inlettoutlet pipes.
2009 Surface Water Design Manual — Appendix A 1/9/2009
A-9
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO.5 - CATCH BASINS AND MANHOLES
Maintenance
Defect or Problem
Condition When Maintenance is Needed
Results Expected When
Component
Maintenance is Performed
Metal Grates
Unsafe grate opening
Grate with opening wider than 7/8 inch.
Grate opening meets design
(Catch Basins)
standards.
Trash and debris
Trash and debris that is blocking more than 20%
Grate free of trash and debris.
of grate surface.
footnote to guidelines for disposal
Damaged or missing
Grate missing or broken member(s) of the grate.
Grate is in place and meets design
Any open structure requires urgent
standards.
maintenance.
Manhole Cover/Lid
Cover/lid not in place
Cover/lid is missing or only partially in place.
Cover/lid protects opening to
Any open structure requires urgent
structure.
maintenance.
Locking mechanism
Mechanism cannot be opened by one
Mechanism opens with proper tools.
Not Working
maintenance person with proper tools. Bolts
cannot be seated. Self-locking coverllid does not
work.
Cover/lid difficult to
One maintenance person cannot remove
Cover/lid can be removed and
Remove
cover/lid after applying 80 lbs. of lift.
reinstalled by one maintenance
person.
1/9/2009 2009 Surface Water Design Manual — Appendix A
A-10
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO.6 - CONVEYANCE PIPES AND DITCHES
Maintenance
Defect or Problem
Conditions When Maintenance is Needed
Results Expected When
Component
Maintenance is Performed
Pipes
Sediment & debris
Accumulated sediment or debris that exceeds
Water flows freely through pipes.
accumulation
20% of the diameter of the pipe.
Vegetation/roots
Vegetation/roots that reduce free movement of
Water flows freely through pipes.
water through pipes.
Contaminants and
Any evidence of contaminants or pollution such
Materials removed and disposed of
pollution
as oil, gasoline, concrete slurries or paint.
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Damage to protective
Protective coating is damaged; rust or corrosion
Pipe repaired or replaced.
coating or corrosion
is weakening the structural integrity of any part of
pipe.
Damaged
Any dent that decreases the cross section area of
Pipe repaired or replaced.
pipe by more than 20% or is determined to have
weakened structural integrity of the pipe.
Ditches
Trash and debris
Trash and debris exceeds 1 cubic foot per 1,000
Trash and debris cleared from
square feet of ditch and slopes.
ditches.
Sediment
Accumulated sediment that exceeds 20% of the
Ditch cleaned/flushed of all sediment
accumulation
design depth.
and debris so that it matches design.
Noxious weeds
Any noxious or nuisance vegetation which may
Noxious and nuisance vegetation
constitute a hazard to County personnel or the
removed according to applicable
public.
regulations. No danger of noxious
vegetation where County personnel
or the public might normally be.
Contaminants and
Any evidence of contaminants or pollution such
Materials removed and disposed of
pollution
as oil, gasoline, concrete slurries or paint.
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Vegetation
Vegetation that reduces free movement of water
Water flows freely through ditches.
through ditches.
Erosion damage to
Any erosion observed on a ditch slope.
Slopes are not eroding.
slopes
Rock lining out of
One layer or less of rock exists above native soil
Replace rocks to design standards.
place or missing (If
area 5 square feet or more, any exposed native
Applicable)
soil.
2009 Surface Water Design Manual — Appendix A 1/9/2009
A-11
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO.9 - FENCING
Maintenance
Defect or Problem
Conditions When Maintenance is Needed
Results Expected When
Component
Maintenance is Performed
Site
Erosion or holes
Erosion or holes more than 4 inches high and 12-
No access under the fence.
under fence
18 inches wide permitting access through an
opening under a fence.
Wood Posts, Boards
and Cross Members
Missing or damaged
parts
Missing or broken boards, post out of plumb by
more than 6 inches or cross members broken
No gaps on fence due to missing or
broken boards, post plumb to within
1'Y2 inches, cross members sound.
Weakened by rotting
Any part showing structural deterioration due to
All parts of fence are structurally
or insects
rotting or insect damage
sound.
Damaged or failed
Concrete or metal attachments deteriorated or
Post foundation capable of
post foundation
unable to support posts.
supporting posts even in strong
wind.
Metal Posts, Rails
Damaged parts
Post out of plumb more than 6 inches.
Post plumb to within 1'Y2 inches.
and Fabric
Top rails bent more than 6 inches.
Top rail free of bends greater than
1 inch.
Any part of fence (including post, top rails, and
Fence is aligned and meets design
fabric) more than 1 foot out of design alignment.
standards.
Missing or loose tension wire.
Tension wire in place and holding
fabric.
Deteriorated paint or
Part or parts that have a rusting or scaling
Structurally adequate posts or parts
protective coating
condition that has affected structural adequacy.
with a uniform protective coating.
Openings in fabric
Openings in fabric are such that an 8-inch
Fabric mesh openings within 50% of
diameter ball could fit through.
grid size.
1 /9/2009 2009 Surface Water Design Manual — Appendix A
A-14
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO. 10 - GATES/BOLLARDS/ACCESS BARRIERS
Maintenance
Defect or Problem
Conditions When Maintenance is Needed
Results Expected When
Component
Maintenance is Performed
Chain Link Fencing
Damaged or missing
Missing gate.
Gates in place.
Gate
members
Broken or missing hinges such that gate cannot
Hinges intact and tubed. Gate is
be easily opened and closed by a maintenance
working freely.
person.
Gate is out of plumb more than 6 inches and
Gate is aligned and vertical.
more than 1 foot out of design alignment.
Missing stretcher bar, stretcher bands, and ties.
Stretcher bar, bands, and ties in
place.
Locking mechanism
Locking device missing, no -functioning or does
Locking mechanism prevents
does not lock gate
not link to all parts.
opening of gate.
Openings in fabric
Openings in fabric are such that an 8-inch
diameter ball could fit through.
Fabric mesh openings within 50% of
grid size.
Bar Gate
Damaged or missing
Cross bar does not swing open or closed, is
Cross bar swings fully open and
cross bar
missing or is bent to where it does not prevent
closed and prevents vehicle access.
vehicle access.
Locking mechanism
Locking device missing, no -functioning or does
Locking mechanism prevents
does not lock gate
not link to all parts.
opening of gate.
Support post
Support post does not hold cross bar up.
Cross bar held up preventing vehicle
damaged
access into facility.
Bollards
Damaged or missing
Bollard broken, missing, does not fit into support
No access for motorized vehicles to
hole or hinge broken or missing.
get into facility.
Does not lock
Locking assembly or lock missing or cannot be
No access for motorized vehicles to
attached to lock bollard in place.
get into facility.
Boulders
Dislodged
Boulders not located to prevent motorized vehicle
No access for motorized vehicles to
access.
get into facility.
Circumvented
Motorized vehicles going around or between
No access for motorized vehicles to
boulders.
get into facility.
2009 Surface Water Design Manual — Appendix A 1/9/2009
A-15
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO. 11 -GROUNDS (LANDSCAPING)
Maintenance
Defect or Problem
Conditions When Maintenance is Needed
Results Expected When
Component
Maintenance is Performed
Site
Trash or litter
Any trash and debris which exceed 1 cubic foot
Trash and debris cleared from site.
per 1,000 square feet (this is about equal to the
amount of trash it would take to fill up one
standard size office garbage can). In general,
there should be no visual evidence of dumping.
Noxious weeds
Any noxious or nuisance vegetation which may
Noxious and nuisance vegetation
constitute a hazard to County personnel or the
removed according to applicable
public.
regulations. No danger of noxious
vegetation where County personnel
or the public might normally be.
Contaminants and
Any evidence of contaminants or pollution such
Materials removed and disposed of
pollution
as oil, gasoline, concrete slurries or paint.
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Grass/groundcover
Grass or groundcover exceeds 18 inches in
Grass or groundcover mowed to a
height.
height no greater than 6 inches.
Trees and Shrubs
Hazard
Any tree or limb of a tree identified as having a
No hazard trees in facility.
potential to fall and cause property damage or
threaten human life. A hazard tree identified by
a qualified arborist must be removed as soon
as possible.
Damaged
Limbs or parts of trees or shrubs that are split or
Trees and shrubs with less than 5%
broken which affect more than 25% of the total
of total foliage with split or broken
foliage of the tree or shrub.
limbs.
Trees or shrubs that have been blown down or
No blown down vegetation or
knocked over.
knocked over vegetation. Trees or
shrubs free of injury.
Trees or shrubs which are not adequately
Tree or shrub in place and
supported or are leaning over, causing exposure
adequately supported; dead or
of the roots.
diseased trees removed.
1/9/2009 2009 Surface Water Design Manual — Appendix A
A-16
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO. 12 - ACCESS ROADS
Maintenance
Defect or Problem
Condition When Maintenance is Needed
Results Expected When
Component
Maintenance is Performed
Site
Trash and debris
Trash and debris exceeds 1 cubic foot per 1,000
Roadway drivable by maintenance
square feet (i.e., trash and debris would fill up
vehicles.
one standards size garbage can).
Debris which could damage vehicle tires or
Roadway drivable by maintenance
prohibit use of road.
vehicles.
Contaminants and
Any evidence of contaminants or pollution such
Materials removed and disposed of
pollution
as oil, gasoline, concrete slurries or paint.
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Blocked roadway
Any obstruction which reduces clearance above
Roadway overhead clear to 14 feet
road surface to less than 14 feet.
high.
Any obstruction restricting the access to a 10- to
At least 12-foot of width on access
12 foot width for a distance of more than 12 feet
road.
or any point restricting access to less than a 10
foot width.
Road Surface
Erosion, settlement,
Any surface defect which hinders or prevents
Road drivable by maintenance
potholes, soft spots,
maintenance access.
vehicles.
ruts
Vegetation on road
Trees or other vegetation prevent access to
Maintenance vehicles can access
surface
facility by maintenance vehicles.
facility.
Shoulders and
Erosion
Erosion within 1 foot of the roadway more than 8
Shoulder free of erosion and
Ditches
inches wide and 6 inches deep.
matching the surrounding road.
Weeds and brush
Weeds and brush exceed 18 inches in height or
Weeds and brush cut to 2 inches in
hinder maintenance access.
height or cleared in such a way as to
allow maintenance access.
Modular Grid
Contaminants and
Any evidence of contaminants or pollution such
Materials removed and disposed of
Pavement
pollution
as oil, gasoline, concrete slurries or paint.
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Damaged or missing
Access surface compacted because of broken on
Access road surface restored so
missing modular block.
road infiltrates.
2009 Surface Water Design Manual — Appendix A 1/9/2009
A-17
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO. 17 - WETVAULT
Maintenance
Defect or Problem
Condition When Maintenance is Needed
Results Expected When
Component
Maintenance is Performed
Site
Trash and debris
Trash and debris accumulated on facility site.
Trash and debris removed from
facility site.
Treatment Area
Trash and debris
Any trash and debris accumulated in vault
No trash or debris in vault.
(includes floatables and non-floatables).
Sediment
Sediment accumulation in vault bottom exceeds
No sediment in vault.
accumulation
the depth of the sediment zone plus 6 inches.
Contaminants and
Any evidence of contaminants or pollution such
Materials removed and disposed of
pollution
as oil, gasoline, concrete slurries or paint.
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Vault Structure
Damage to wall,
Cracks wider than 1/2-inch, any evidence of soil
Vault is sealed and structurally
frame, bottom, and/or
entering the structure through cracks, vault does
sound.
top slab
not retain water or qualified inspection personnel
determines that the vault is not structurally
sound.
Baffles damaged
Baffles corroding, cracking, warping and/or
Repair or replace baffles or walls to
showing signs of failure or baffle cannot be
specifications.
removed.
Ventilation
Ventilation area blocked or plugged.
No reduction of ventilation area
exists.
Inlet/Outlet Pipe
Sediment
Sediment filling 20% or more of the pipe.
Inlet/ouflet pipes clear of sediment.
accumulation
Trash and debris
Trash and debris accumulated in inlet/outlet
No trash or debris in pipes.
pipes (includes floatables and non-floatables).
Damaged
Cracks wider than 1/2-inch at the joint of the
No cracks more than %-inch wide at
inlet/outlet pipes or any evidence of soil entering
the joint of the inlet/outlet pipe.
at the joints of the inlet/outlet pipes.
Gravity Drain
Inoperable valve
Valve will not open and close.
Valve opens and closes normally.
Valve won't seal
Valve does not seal completely.
Valve completely seals closed.
Access Manhole
Access cover/lid
Access cover/lid cannot be easily opened by one
Access cover/lid can be opened by
damaged or difficult to
person. Corrosion/deformation of cover/lid.
one person.
open
Locking mechanism
Mechanism cannot be opened by one
Mechanism opens with proper tools.
not working
maintenance person with proper tools. Bolts
cannot be seated. Self-locking cover/lid does not
work.
Cover/lid difficult to
One maintenance person cannot remove
Cover/lid can be removed and
remove
cover/Ild after applying 80 Ibs of lift.
reinstalled by one maintenance
person.
Access doors/plate
Large access doors not flat and/or access
Doors close flat and covers access
has gaps, doesn't
opening not completely covered.
opening completely.
cover completely
Lifting Rings missing,
Lifting rings not capable of lifting weight of door
Lifting rings sufficient to lift or
rusted
or plate.
remove door or plate.
Ladder rungs unsafe
Missing rungs, misalignment, rust, or cracks.
Ladder meets design standards.
Allows maintenance person safe
access.
2009 Surface Water Design Manual — Appendix A 1/9/2009
A-23
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO.21 - STORMFILTER (CARTRIDGE TYPE)
Maintenance
Defect or Problem
Condition When Maintenance is Needed
Results Expected When
Component
Maintenance is Performed
Site
Trash and debris
Any trash or debris which impairs the function of
Trash and debris removed from
the facility.
facility.
Contaminants and
Any evidence of contaminants or pollution such
Materials removed and disposed of
pollution
as oils, gasoline, concrete slurries or paint.
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Life cycle
System has not been inspected for three years.
Facility is re -inspected and any
needed maintenance performed.
Vault Treatment
Sediment on vault
Greater than 2 inches of sediment.
Vault is free of sediment.
Area
floor
Sediment on top of
Greater than % inch of sediment.
Vault is free of sediment.
cartridges
Multiple scum lines
Thick or multiple scum lines above top of
Cause of plugging corrected,
above top of
cartridges. Probably due to plugged canisters or
canisters replaced if necessary.
cartridges
underdrain manifold.
Vault Structure
Damage to wall,
Cracks wider than '%-inch and any evidence of
Vault replaced or repaired to design
Frame, Bottom, and/or
soil particles entering the structure through the
specifications.
Top Slab
cracks, or qualified inspection personnel
determines the vault is not structurally sound.
Baffles damaged
Baffles corroding, cracking warping, and/or
Repair or replace baffles to
showing signs of failure as determined by
specification.
maintenance/inspection person.
Filter Media
Standing water in
9 inches or greater of static water in the vault for
No standing water in vault 24 hours
vault
more than 24 hours following a rain event and/or
after a rain event.
overflow occurs frequently. Probably due to
plugged filter media, underdrain or outlet pipe.
Short circuiting
Flows do not properly enter filter cartridges.
Flows go through filter media.
Underdrains and
Sediment/debris
Underdrains or clean -outs partially plugged or
Underdrains and clean -outs free of
Clean -Outs
filled with sediment and/or debris.
sediment and debris.
Inlet/Outlet Pipe
Sediment
Sediment filling 20% or more of the pipe.
Inlet/outlet pipes clear of sediment.
accumulation
Trash and debris
Trash and debris accumulated in inlet/outlet
No trash or debris in pipes.
pipes (includes floatables and non-floatables).
Damaged
Cracks wider than '/z-inch at the joint of the
No cracks more than '/,inch wide at
inlet/outlet pipes or any evidence of soil entering
the joint of the inlet/outlet pipe.
at the joints of the inlet/outlet pipes.
Access Manhole
Cover/lid not in place
Cover/lid is missing or only partially in place.
Manhole access covered.
Any open manhole requires immediate
maintenance.
Locking mechanism
Mechanism cannot be opened by one
Mechanism opens with proper tools.
not working
maintenance person with proper tools. Bolts
cannot be seated. Self-locking cover/lid does not
work.
Cover/lid difficult to
One maintenance person cannot remove
Cover/lid can be removed and
remove
cover/lid after applying 80 Ibs of lift.
reinstalled by one maintenance
person.
Ladder rungs unsafe
Missing rungs, misalignment, rust, or cracks.
Ladder meets design standards.
Allows maintenance person safe
access.
Large access
Damaged or difficult
Large access doors or plates cannot be
Replace or repair access door so it
doors/plate
to open
opened/removed using normal equipment.
can opened as designed.
1 /9/2009 2009 Surface Water Design Manual — Appendix A
A-30
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO.21 - STORMFILTER (CARTRIDGE TYPE)
Maintenance
Defect or Problem
Condition When Maintenance is Needed
Results Expected When
Component
Maintenance is Performed
Gaps, doesn't cover
Large access doors not flat and/or access
Doors close flat and cover access
completely
opening not completely covered.
opening completely.
Lifting Rings missing,
Lifting rings not capable of lifting weight of door
Lifting rings sufficient to lift or
rusted
or plate.
remove door or plate.
2009 Surface Water Design Manual — Appendix A 1/9/2009
A-31