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DRAFT
TECHNICAL INFORMATION REPORT
MEYER SHORT PLAT
SE 173RD STREET
, WA 98055
(
-\ -('.""'\. \ \ \ -.
The Concept Group
650 South Orcas St, Suite 214 • Seattle, WA 98168 • (206) 658-0125
Land De v elopment & Civil Engineering Consultants
DRAFT
TECHNICAL INFORMATION REPORT
MEYER TOWNHOMES SHORT PLAT
10839 SE 173RD STREET
RENTON, WA 98055
September 2008
I cert ify that this technical information report and all attachments were prepared
either by me or my technical stqff working directly under my supervision.
EXPIRES 09/13/09
T HE CONCE PT GROUP
Table of Contents
ACRONYM TERMINOLOGY .................................................................................................................................... I
SECTION 1: PROJECT OVERVIEW ......................................................................................................................... 1
SITE INFORMATION ............................................................................................................................................ 1
DRAINAGE BASIN .............................................................................................................................................. 1
SOILS INFORMATION............................ . ................................................................................................... 1
SECTION 2: CONDITIONS AND REQUIREMENTS .................................................................................................... 2
EXISTING SITE HYDROLOGY.................. . ............................................................................................... 2
DEVELOPED SITE HYDROLOGY ........................................................................................................................ 2
DESIGN REQUIREMENTS................... . .......................................................................................... 2
SECTION 3: LEVEL 1 0FFSITE ANALYSIS .............................................................................................................. 2
DOWNSTREAM ANALYSIS................. . ................................................................................................. 2
DISCHARGE AT NATURAL (EXISTING) LOCATION .............................................................................................. 2
SECTION 4: FLOW CONTROL/ WATER QUAI.ITY ANALYSIS & DESIGN •.•......................••.•.••.••.••.........••.••.••...••.• 3
FLOW CONTROL ................................................................................................................................................ 3
DRAINAGE ANALYSIS (KCRTS)....... . .......................................................................................... 3
INFILTRATION FACILITY DESIGN....... . ............................................................................................... 3
WATER QUALITY .............................................................................................................................................. .4
SECTION 5: CONVEYANCE SYSTEM ....................................................................................................................... 4
100-YEAR FLOOD/OVERFLOW CONDIT[ON ....................................................................................................... .4
SECTION 6: SPECIAL REPORTS AND Sn;DIES ....................................................................................................... 4
SECTION 7: OTHER PERMITS .•.••.••.••••..........................•...••.••.••.••.•..•....••.••.••.••.•.••.••..•..........................••.•........•.••. 4
SECTION 8: CSWPP (EROSION CONTROL) ANALYSIS AND DESIGN .................................................................... 4
CONSTRUCTION SEQUENCE AND PROCEDURE .................................................................................................... 5
TRAPPING SEDIMENT .......................................................................................................................................... 5
SECTION 9: BOND QUANTITIES AND DECLARA TJONS OF COVENANTS .....................•.••.••.••.•..•.••.••.••.••.•.••.••.••.•.••. 6
SECTION 10: OPERATIONS AND MAINTENANCE ................................••.••.•..•.••.••.•..••.•..•.••.••.•.....•..•.••.••.•.••..•......... 6
Appendices
Appendix A: Vicinity Map, Site Photos and Property Information
Appendix B: Soils Information
Appendix C: Proposed Drainage Plan
Appendix D: Flow Control, Water Quality and Infiltration Design
Appendix E: Erosion Control Plans
Appendix F: Maintenance Procedures
ACRONYM TERMINOLOGY
,, Inch
cf Cubic Feet
cfs Cubic Feet per Second
CMP Corrugated Metal Pipe
DI Ductile Iron
HOPE High Density Polyvinyl Ethane
JUD Joint Use Driveway
KCSWM King County Surface Water Manual
PGIS Pollution Generali ng Impervious Surface
PVC Polvvinvl Chloride
RCP Reinforced Concrete Pipe
scs Soils Service Conservation
Sq Ft Sauare foot
General Notes:
1. The information contained in this report is based on a topography and boundary
survey prepared by Dryco Surveying, Inc., the King County Assessor's map, and
on-site observations and measurements. If any changes are made to these
drawings or the site that will affect the calculations in this report, the engineer
shall be notified. All construction based on this report shal I be stopped and sh al I
not proceed until the impact of the changes can be reflected in a supplement
report.
2. This report is based on limited subsurface exploration. During construction, if
soils conditions are found that are significantly different from those identified in
this report, construction should stop until those items affected by the changed
conditions can be identified and adjusted, if needed to reflect the changed
conditions.
3. This report is prepared for the sole use of client for the purpose of subdividing
the property located at 10839 SE 173'd Street; Renton, WA 98055. All other
uses are expressly prohibited without prior written approval from the engineer.
4. All construction related to the drainage system for this project will be in
accordance with the 1990 King County Surface Water Design Manual and the
City of Renton current standards unless specifically mentioned in this report
and/or approved by the City of Renton.
Meyer Town homes Short Plat -DRAFT Technical Information Report September 2008
SECTION 1: PROJECT OVERVIEW
The property is located at 10839 SE 1 73'd Street in the City of Renton, Washington.
The property has one (1) single family residence. The project proposes to short plat the
existing parcel into three (3) single family residential lots. Proposed improvements
include the construction of an attached two-unit townhouse, a Private Access/Utility
tract, associated uti Ii ties and stormwater management facilities and the relocation of the
existing house.
Site Information
Refer to Appendix A for the Vicinity Map and site photos of this project.
Location: 10839 SE 173'd Street; Renton, Washington 98055
Section/Township/Range: SW 14 of SE 14 Sec. 29, T.23N, R.4E of W.M.
Size: 12,722 sq ft (approximately 0.29 acre)
City, County, State: Renton, King County, Washington
Governing Agency: City of Renton
Design Criteria: 1990 King County Surface Water Manual
Water and Sewer District: Soos Creek Water & Sewer District
Drainage Basin
The entire property drains to one basin with a contributing area of 0.29 acres. The
general topography of the site slopes from southeast to northwest. Elevations on the site
vary from a high point of 420 feet at the northern property line to 412 feet at the
southern property line, with grades varying from 1.0% to 8.0%.
Soils Information
Soils Survey
The Soil Survey prepared by the United States Department of Agriculture Natural
Resource Conservation Service, indicates the soil type within the project as AmC
(Alderwood material), SCS Hydrologic Soil Group C. This Alderwood soil series
contains moderately well drained soils consisting predominately of Alderwood material
with slopes between six (6) to fifteen (15) percent. Runoff and erosion hazards from
this soil type is medium. This series of soil is suitable for urban development.The
KCRTS equivalent soils group, as defined in Table 3.2.2.B of the 2005 King County
Surface Water Manual (KCSWM), is Till.
Refer to Appendix B for the Soils Survey Map & sieve analysis.
The Concept Group Page I
Meyer Townhomes Short Plat -DRAFT Technical Information Report
SECTION 2: CONDITIONS AND REQUIREMENTS
Existing Site Hydrology
September 2008
The site is currently developed with one single-family residence. The general
topography slopes from southeast to northwest. Stormwater runoff presently infiltrates
to native soils. During heavy rainfall events, stormwater sheet flows towards SE 173'd
Street into the system of grass-lined ditches and driveway culverts.
Developed Site Hydrology
The project proposes to short plat the existing parcel into three (3) single family
residential lots. Each of the new residential lots will consist of a total of approximately
1,400 sq ft to 2,000 sq ft of new impervious surface with the remainder of the lots
consisting of landscape and lawns.
Stormwater for the roof, driveway and Private Access Tract will be infiltrated to native
soils. Refer to the Drainage Plan in Appendix C for the proposed storm drainage
design.
Design Requirements
The 1990 King County Surface Water Manual sets forth the drainage requirements for
this project. The drainage requirements are summarized in Table 1.
Table 1 -Jurisdictional Reauirements
Peak Run-off Control: NIA -based on 0.5 els exemption
Water Qua I ity: NIA -based on surface area exemption
Conveyance: 25-year developed flow
Downstream Analysis: Level 1
SECTION 3: LEVEL 1 0FFSITE ANALYSIS
Downstream Analysis
Stormwater runoff presently infiltrates to native soils. During heavy rainfall events,
Stormwater runoff is conveyed in a series of grass-lined ditches and 12-inch driveway
culverts along SE 173'd Street. Stormwater continues to flow west towards 1 OB'h Way SE
where it discharges to a large wetland via a 36-inch culvert under 108'h Way SE. There
is no sign of erosion within a quarter mile of the project.
Discharge at Natural (Existing) Location
Stormwater presently infiltrations to native soils. During heavy rainfall events,
stormwater may sheet flow to the ditches along SE 173'd Street.
The Concept Group Page 2
Meyer Townhomes Short Plat -DRAFT Technical Information Report
SECTION 4: FLOW CONTROL/ WATER QUALITY ANALYSIS & DESIGN
Flow Control
September 2008
This project will create approximately 8,142 square feet of new impervious surface.
Flow control facilities are not required because the project creates less than 0.50 cfs
increase in discharge from the existing condition for the 100-year storm event per the
KCRTS data below. Refer to Appendix D for flow control calculations.
Drainage Analysis (KCRTS)
The King County Runoff Time Series (KCRTS) Hydrologic Model is the required
methodology under the 1990 King County Surface Water Design Manual for sizing
detention facilities. The project is located in the Basic Flow Control Area. Tables 2-4
summarize the KCRTS inputs.
Table 2 -Existing Conditions
Areas (acres)
Till Forest Till Grass Impervious
0.00 0.26 0.03
Table 3 -Developed Conditions
Areas (acres)
Till Forest Till Grass Impervious
0.00 0.10 0.19
Table 4 -KCRTS Inputs
Rainfall Region SeaTac
Scale Factor 1.0
Tables 5 summarizes the KCRTS output. Without taking into account the proposed
infiltration trenches, the 100-year peak flow rate of the developed site is only 0.042 cfs
higher than the existing condition.
Table 5 -100 Year Peak Runoff Rates (els)
Existing Condition Developed Condition Difference in Discharge
0.069 0.111 0.042
Infiltration Facility Design
Although infiltration facilities are not required for this project based on the 0.50 cfs
exemption; infiltration facilities are proposed as a BMP to help reduce the stormwater
impacts of the proposed development.
A soils analysis was performed and it was determined that the project soils can be
classified as medium sand. Per section C.2.2.3, infiltration trenches must be at least 30
feet in length (60 square feet bottom area) per 1,000 square feet of impervious surface
The Concept Group Page 3
Meyer Town homes Short Plat -DRAFT Technical Information Report September 2008
based on a 2 feet wide bottom. The infiltration trenches for the roof drains have been
designed with an overflow outlet to sheet flow storm water during heavy rainfall
events. Refer to Table 2 and Appendix D for infiltration trench calculations and details.
Table 2 -Infiltration Facility Design
Areas (SF)
New Impervious Surface Required Infiltration Provided Infiltration
Bottom Area Bottom Area
1,414 (lot 1) 0 combined w/ access road system
1,650 (lot 21 0 combined w/ access road system
1,978 (lot 3) 0 120
3,100 (shoulder & access 0 265
driveway)
Water Quality
Although the project will create 8,142 square feet of new impervious surface,
approximately 4,280 square feet is pollution-generating impervious surface (PGIS).
PGIS is defined as "an impervious surface considered to be a significant source of
pollutants in surface and storm water runoff. Such surfaces include those subject to
vehicular use or storage of erodible or leachable materials, wastes, or chemicals, and
which receive direct rainfall or the run-on or blow-in of rainfall." Non-metal rooftops
are not considered PGIS; therefore, are not included in the PGIS area calculations.
Water quality is not required for this project because the project does not create more
than 5,000 sq ft of pollution generating impervious surfaces as defined in the KCSWM.
Refer to Appendix D for water quality calculations
SECTION 5: CONVEYANCE SYSTEM
This project does not include any proposed conveyance systems.
100-Year Flood/Overflow Condition
Overflow of the stormwater infiltration facility will sheet flow to the eastern properties
and eventually discharge to the drainage ditches located along SE 192"d Street.
SECTION 6: SPECIAL REPORTS AND STUDIES
There are no special reports or studies are expected to be prepared for this project.
SECTION 7: OTHER PERMITS
Permit for this project included:
• Short Plat Approval
• Building Construction Perm it
SECTION 8: CSWPP (EROSION CONTROL) ANALYSIS AND DESIGN
All erosion and sediment control measures shall be governed by the requirements of
the City of Renton. An Erosion and Sedimentation Control plan has been prepared to
The Concept Group Page 4
Meyer Town homes Short Plat -DRAFT Technical Information Report September 2008
assist the contractor in complying with these requirements and designed to prevent
sediment-laden run-off from leaving the site during construction. Refer to Appendix E
for Erosion Control plans and details.
The erosion potential of the site is influenced by four major factors: soil characteristics,
vegetative cover, topography, and climate. Erosion/ sedimentation control is achieved
by a combination of structural measures, cover measures, and construction practices
that are tailored to fit the specific site.
Construction Sequence and Procedure
Prior to the start of any grading activity upon the site, all erosion control measures,
including installation of a stabilized construction entrance, shall be installed in
accordance with the construction documents.
The best construction practice will be employed to properly clear and grade the site
and to schedule construction activities. The planned construction sequence for the
construction of the site is as fol lows:
1. Pre-construction meeting.
2. Post sign with name and phone number of ESC supervisor (may be consolidated
with the required notice of construction sign).
3. Flag or fence clearing limits.
4. Install catch basin protection if required.
5. Grade and install construction entrance(s).
6. Install perimeter protection (silt fence, brush barrier, etc.).
7. Construct sediment ponds and traps.
8. Grade and stabilize construction roads.
9. Construct surface water controls (interceptor dikes, pipe slope drains, etc.)
simultaneously with clearing and grading for project development.
10. Maintain erosion control measures in accordance with King County standards
and manufacturer's recommendations.
11. Relocate erosion control measures or install new measures so that as site
conditions change the erosion and sediment control is always in accordance
with the King County Erosion and Sediment Control Standards.
12.Cover all areas that will be unworked for more than seven days during the dry
season or two days during the wet season with straw, wood fiber mulch,
compost, plastic sheeting or equivalent.
13.Stabilize all areas that reach final grade within seven days.
14. Seed or sod any areas to remain unworked for more than 30 days.
15. Upon completion of the project, all disturbed areas must be stabilized and
BMPs removed if appropriate.
Trapping Sediment
Structural control measures will be used to reduce erosion and retain sediment on the
construction site. The control measures wi 11 be selected to fit specific site and seasonal
conditions.
The Concept Group Page 5
Meyer Town homes Short Plat -DRAFT Technical Information Report September 2008
The following structural items will be used to control erosion and sedimentation
processes:
• Temporary gravel construction entrance
• Filter fabric fences (Silt fences)
• Ground cover measures such as straw cover and/or hydroseeding
• Inlet protection
Vehicle tracking of mud off-site shall be avoided. Installation of a gravel construction
entrance will be installed at a location to enter the site. The entrances are a minimum
requirement and may be supplemented if tracking of mud onto public streets becomes
excessive.
SECTION 9: BOND QUANTITIES AND DECLARATIONS OF COVENANTS
None known at the time this report was prepared.
SECTION 10: OPERATIONS AND MAINTENANCE
The owner or operator of the project shall be responsible for maintaining the
stormwater facilities in accordance with the requirements as attached in Appendix F.
Proper maintenance is important for adequate functioning of the stormwater facilities.
If it is unclear whether a problem exists, contact a Professional Engineer.
The Concept Group Page 6
Meyer Townhomes Short Plat -DRAFT Technical Information Report
The Concept Group
Appendix A
Vicinity Map, Site Photos
and Property Information
September 2008
Appendices
Meyer T own homes Sh ort Plat -DRAFT Tec h nica l I nformation Report
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Appendices
Meyer Tow nhomes Short Plat -DRAFT Tech nical Information Report Septe mber 2008
View of front yard of subject property.
View of back ya rd o f subject property.
The Concept Group Appendices
Meyer T ownhomes Short Plat -DRAFT Te chn ical Information Rep ort September 2008
Driveway cu lve rt in fr o nt of subject property .
The Concept Group Appendi ces
Meyer Townhomes Short Plat -DRAFT Techni cal I nformat ion Report September 2008
Lookin g so uth on l 0811 Way SE
Th e Concept Group Appendi ces
Meyer Town homes Short Plat -DRAFT Techni cal Information Report September 2008
The Concept Group Appendices
UI Kins County
Assessor information for parcel number 1626800060
Taxpayer name MARSHALL CHARLES Parcel number 1626800060
Mailing address 10839 SE 173RD ST
RENTON WA 98055
Tax Account number 162680006002
Address(es) al this parcel 10839 SE 173RD ST 98055
~~ascription--------~---~---
CLIFFORDS 1ST ADD
-1-S8l8s/QUiC1airTisrrransters
Levy code
Jurisdiction
Present use
Appraised value
-------------~---~---------
Sale date Sale price Buyer Seller ·,$:
05-27-2008 $0 MARSHALL CHARLES MARSHALL JENNIFER T
05-22-2008 $281,500 MARSHALL CHARLES SEFRIOUI ANTISSAR
04-12-2007 $221,000 SEFRIOUI ANTISSAR scon DUANE L
2128
RENTON
Single Family(Res Use/Zone)
$187,000
234 84_5_4. None
227782~.2~--~2~0gOb70~4~1~3~0~0f23~1g4t__~S~<~at~"~'"'Y"i'.."'""'a~rra~o~<yy_cOe,eee~d_<E~,~ta~<~e~S~e~tt~le~m~e~o~t
I_ Parcel description
Property name Plat name CLIFFORD'S 1 ST ADD Waler system WATER DISTRICT
Property type R • RESIDENTIAL Plat block 2
Present use Single Famlly(Res Use/Zone) Plallot 6
Loi area 12,722 sq. ft. (0.29 acres) Q-S-T-R SE-29-23-5
' Residential buildingd~sc~rip~t~io~n~-----
Building
Year built
Year renovated
Stories
Building grade
1 of 1
1952
•
6 • Low Average
Condi lion Average
Finished basement grade NONE OR UNKNOWN
Total living sq. ft.
1st floor sq. ft.
Half floor sq. ft.
2nd floor sq. ft.
Upper floor sq. ft.
Total basement sq. ft.
Finished basement sq. ft.
Basement garage sq. ft
Attached garage sq. ft.
Open porch sq. ft.
Enclosed porch sq. ft.
Deck sq. ft.
Sewer system PUBLIC
Access PUBLIC
Street surface PAVED
1,160 Bedrooms 3
1,160 Baths
0 1/2 baths 0
0 3/4 baths 0
0 Single story fireplace
0 Multi-story fireplace 0
0 Free-standing fireplace •
0 Percent brick or stone 0
0 Daylight basement N
60 Heat system Elec BB
0 Heat source Electricity
0
2008 TAXABLE
2007 TAXABLE
2006 TAXABLE
NONE OR UNKNOWN
NONE OR UNKNOWN
NONE OR UNKNOWN
$71,000 (land)
+ lli..QQQ (lmpro11emeols)
$170,000 (total)
$63,000 (land)
+ lli.2QQ {impro11emeols)
$145,000 (total)
$59,000 (land)
+ lZI.2QQ (impfOllernents)
--------------'$_,_,13"C'6,000 (~
.... Related resources ..
+ $113 000 (improvernenls)
$187,000 (total)
$71.000 (land)
+ $99 000 (improvements)
$170,000 (total)
$63.000 (land)
+ $82 000 (improvements)
$145,000 {total)
$59.000 (land)
+ $77 ODO (improvements)
$136,000 (total)
King County Assessor: Submit a request to correct information in this report
King County Assessor: eReal Prop arty Report (PDF format requires Acrobat)
King County Assessor: Quarter Section Map (PDF format requires Acrobat)
King County GIS: Property information FAQ
King County GJS: Districts and Development Conditions Report (a detailed report about the location of this property)
King County DOES: Permit Applications Report (for unincorporated areas only)
King County Treasury Operations: Proparty Tax Information for this property
King County Recorders Office: Excise Tax Affidavits Report
King County Recorders Office: Scanned Images of plats.
King County Recorders Office: Scanned images of surveys and other map dcg;1,1m_i?nts.
Open iMAP to this property (requires a high speed internet connection)
Open Parcel Viewer to this property (any connection speed, but less features than iMAP)
This report was generated on 9/26/200812:13:08 PM
Contact us at g,scentcr@k1ogco11nty gov.
© 2008 King County
U) King County
King County Districts and Development Conditions for parcel 1626800060
Parcel number 1626800060 Drainage Basin
Address 10839 SE 173RD ST Wa!!l!C§hed
Jurisdiction Renton WRIA
Zipcode 98055 PLSS
Kroll Map page 601 Latitude
Thomas Guide page ••• Longitude
1·-Electoral Districts
Voting district RNT 11-0804
King County Council distnct District 5, Julia Patterson
(206) 296-1005 t:iiJ
Congressional district
Leglslalive district
School district
9
11
Renton #403
Black River
DUW!!rnish • Green River
Ouwami_~tl_-Gr~en (9J
SE-29-23-5
47.4472
-122.19475
Fire district
Water d1str1cl
Sewer district
Water&. Sewer district
-----------~=cc-~~-------------------
does not apply
does not apply
does not apply
Soos Creek Water & Sewer District
Parks & Recreation distr1cl does not apply
Hospital district
Sealtle school board districl does not apply (not in SeaWe) Rural library district
Public Hospital District No. 1
does not apply
Dislrict Court electoral district Southeast Tribal Lands? No
King County zoning
P-Suffix conditions
Comprehensive Plan
NA, c:he<:k with Jurisdiction
None
um
Urban Growth Area Urban
Unincorporated Area Council does not apply
Community Planning Area Soos Creek
Coal mine hazards? Yes
Erosion hazards? None mapped
Landslide hazards? None mapped
Seismic hazards? None mapped
Water serv,c:i; QJB::J_'.l_l_n_g_ar_e,a
Roads MPS _~Qrll;'
does not apply
334
Jransportat,on concurrency zone 784
Forest Production district? No
Agricultural Production district? No
Rural cle.irirm lmrts ;rnply? No
Critical aquifer rechsrqe <:irea? None mapped
100-yearflood plain? None mapped
WeUands at this parcel? None mapped
This report was generated on 9/26/2008 12:15:04 PM
Contact us at giscenter@kingcounty.gov.
(c) 2008 King Counly
Meyer Townhomes Short Plat -DRAFT Technical Information Report
The Concept Group
Appendix B
Soils Information
September 2008
Appendices
560520 560540 560560
I I I
560520 560540 560560
N
A 0 15 30 60
0 50 100 200
USDA Natural Resources 1iii Conservation Service
Soil Map-King County Area , Washington
(Meyer Townho mes Short Plat)
560580 560!l00 560620
I I I
560580 560600 560620
Meters
90
Feet
300
Web Soil Survey 2.0
National Coopera ti ve Soi l Survey
560640
I
560640
560660 560680
I == 0
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9/26/2008
Page 1 of 3
=
Soil Map-King County Area, Washington
(Meyer Townhomes Short Plat)
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
D Area of Interest (AOI)
Soils
Soil Map Units
Special Point Features
"" Blowout
181 Borrow Pit
* Clay Spot
• Closed Depression
X Gravel Pit
Gravelly Spot
@ Landfill
A Lava Flow ... Marsh .. Mine or Quarry
@ Miscellaneous Water
@ Perennial Water
V Rock Outcrop
+ Saline Spot
Sandy Spot
-=-Severely Eroded Spot
~ Sinkhole
9 Slide or Slip
/6 Sadie Spot
s Spoil Area
() Stony Spot
Natural Resources
Conservation Service
Ol Very Stony Spot
t Wet Spot .. Other
Speclal Line Features
"'" Gully
Short Steep Slope
A, Other
Political Features
Municipalities
• Cities
D Urban Areas
Water Features
:::::::J Oceans
~ Streams and Canals
Transportation
+++ Ralls
Roads
"""' Interstate Highways
,,,.,, US Routes
State Highways -Local Roads
Other Roads
Original soil survey map sheets were prepared at publication scale.
Viewing scale and printing scale, however, may vary from the
original. Please rely on the bar scale on each map sheet for proper
map measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL: http://websoilsurvey.nrcs.usda.gov
Coordinate System: UTM Zone 10N
This product is generated from the USDA-NRCS certified data as of
the version date(s) listed below.
Soil Survey Area:
Survey Area Data:
King County Area, Washington
Version 4, Nov 21, 2006
Dale(s) aerial images were photographed: 7/10/1990; 7/18/1990
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result. some minor shifting
of map unit boundaries may be evident.
Web Soil Survey 2.0
National Cooperative Soil Survey
9/26/2008
Page 2 of 3
Drainage Class-King County Area, Washington Meyer T ownhomes Short Plat
Drainage Class
Drainage Class-Summary by Map Unit -King County Area, Washington
Map unit symbol Map unit name I Rating Acres in AOI Percent of AOI
AgC Alderwood gravelly Moderately well drained 0.8 14.5%
sandy loam, 6 to 15
percent slopes --· ----
C 1
Arents, Alderwood Moderately well drained 4.8
_ 85.5% I material, 6 to 15
percent slopes
--
I Totals for Area of Interest (AOI) -~---______ s.a I ____ 100.0% I
Description
"Drainage class (natural)" refers to the frequency and duration of wet periods under
conditions similar to those under which the soil formed. Alterations of the water
regime by human activities, either through drainage or irrigation, are not a
consideration unless they have significantly changed the morphology of the soil.
Seven classes of natural soil drainage are recognized-excessively drained,
somewhat excessively drained, well drained, moderately well drained, somewhat
poorly drained, poorly drained, and very poorly drained. These classes are defined
in the "Soil Survey Manual."
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Natural Resources
Conservation Service
Web Soil Survey 2.0
National Cooperative Soil Survey
9/2612008
Page 3 of 3
3.2.2 KCRTS/RUNOFF FILES METHOD-GENERATING 71ME SERIES
TABLE 3.2.2.B EQUIVALENCE BETWEEN SCS SOIL TYPES AND KCRTS SOIL TYPES
SCS Soil Type scs KCRTS Soll Notes
Hydro logic Group
Soil Group
Alderwood (AoB, AnC, AaDl C Till
Arents, Alderwood Material (AmB, AmC) C Till
Arents, Everett Material (An) B Outwash 1
Beausite /BeC, BeD, BeFI C Till 2
Bellingham (Bh) D Till 3
Brisool Br) D Till 3
Buckley Bu) D Till 4
Earlmont (Ea) D Till 3
Edgewick (Ed) C Till 3
Everett EvB, EvC, EvD. EwC) AIB Outwash 1
Indianola (lnC, lnA, lnD) A Outwash 1
Kitsap (KpB, KpC, KpD) C Till
Klaus KsC) C Outwash 1
Neilton NeC) A Outwash 1
Newbero (Nal B Till 3
Nooksack (Nkl C Till 3
Norma (No) D Till 3
Orcas (Or) D Wetland
Oridia (Os) D Till 3
Ovall OvC, OvD, OvFl C TIii 2
Pilchuck /Pc) C Till 3
Puget Pu) D Till 3
Puyallui (Pvl B Till 3
Ragnar RaC., RaD, RaC, RaEl B Outwash 1
Renton Re) D nu 3
Salal (Sa) C Till 3
Sammamish (Sh) D Till 3
Seattle (Sk) D Wetland
Shalcar (Sm) D Till 3
Si {Sn) C Till 3
Snohomish (So, Sr) D Till 3
Sultan Su) C Till 3
Tukwila {Tu) D TIii 3
Woodinville (Wo) D Till 3
Notes:
1. Where outwash soils are saturated or underlain at shallow depth (<5 feet) by glacial till, they should
be treated as till soils.
2. These are bedrock soils, but calibration of HSPF by King County DNRP shows bedrock soils to
have similar hydrologic response to till soils.
3. These are alluvial soils, some of which are underlain by glacial till or have a seasonally high water
table. In the absence of detailed study, these soils should be treated as till soils.
4. Buckley soils are formed on the low-permeability Osceola mudflow. Hydrologic response is
assumed to be similar to that of till soils.
2005 Surface Water Design Manual 112412005
3-25
Report to:
Anna T. Nguyen, P.E.
The Concept Group
Seattle, WA
Final Report for:
Soil samples submitted for analysis
Meyer T ownhomes Short Plat
LabCor Portland Job No.: 082006 [S5]
Particle Sizing and Moisture Content of Soil Samples
Analyst: Liza Shaw
September 23, 2008
LabCor Portland, Inc.
1.1. Test Methods
For particle sizing, soils were dried to ambient conditions. After samples were sufficiently dry, the samples
were passed through a series of sieves and the fraction remaining on each sieve was weighed. The fraction of
the sample that was left in the pan after sieving represents fine silt and clays. To further break down this
fraction requires hydrometer analysis at an extra cost.
General classification of soil types were as follows:
Classification
Coarse Gravel
Medium Gravel
Fine Gravel
Verv Fine Gravel
Verv Coarse Sand
Coarse Sand
Medium Sand
Fine Sand
Very Fine Sand
Silt
Clay
1.2. Moisture Content
Meyer Kent Hole 2 [S5]
Initial
w,,;,,htln\ 1165.00
Dried
Weiahtfn\ 1101.80
Moisture
Weicht 63.20
% Moisture 5.42
4321 SW Corbett Ave, Ste. A
Portland, OR 97239
Particle diameter
>19.0mm
>9.5mm
>4.75mm
>2.0mm
>850µm
>425um
>250µm
>106µm
>75µm
>63µm
<63µm
Tel: (503) 224-5055 Fax: (503} 228-8282
Page 2 of4
LabCor Portland, Inc.
2.2. Particle Size Breakdown
Meyer Kent Hole 2 [S5]
Coarse
Gravel
Sieve
Size >19.0mm
Weight
In\ 0.00
% of Total 0.00
Very Very Very
Medium Fine Fine Course Coarse Medium Fine Fine
Gravel Gravel Gravel Sand Sand Sand Sand Sand Silt
>9.5mm >4.75mm >2.0mm >850um >425um >250um >106um >75um >63um
16.40 41.60 55.80 46.80 117.00 171.40 263.80 68.80 65.00
1.49 3.78 5.06 4.25 10.62 15.56 23.94 6.24 5.90
Meyer Kent Hole 2 [S5]
Jo. oo r-:::-:::::-c::--:-:-----::::;~:;,:;:;;:;;;::;-:-;;-c::717~--;-:-:-:---:-i
iii ...
0
1-
'o
#.
25.00 fi*'~r::,----~=
20.00 +::-~~7---~~~~
15.00
10.00 f-,-~~;ir------,~ei
5.00
0.00 .i.;;..-;:::2:;;;.:;,._~-~..;..;;;;:..;...;;.;..,.~;....;..~~""""';a;.._~ ........ _.
Particle Size
Clav
Fines(<63um)
244.60
22.20
4321 SW Corbett Ave, Ste. A
Portland, OR 97239
Tel: (503) 224-5055 Fax: (503) 228-8282
Page 3 of4
Total
1091.20
99.04
LabCor Portland, Inc.
This test report relates only to the items tested in this report. Results are subject to the variation of field sub
sampling, the accuracy of the balance as well as other variations within the procedure.
If further clarification of these results is needed, please do not hesitate to call. Thank you for allowing the staff
at Lab/Cor Portland, Inc. the opportunity to provide you with analytical services.
Sincerely,
.,
John Harris
Laboratory Director
4321 SW Corbett Ave, Ste. A
Portland, OR 97239
Tel: (503) 224-5055 Fax: (503) 228-8282
Page 4 of 4
Meyer Townhomes Short Plat -DRAFT Technical Information Report
The Concept Group
Appendix C
Proposed Drainage Plan
September 2008
Appendices
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MEYER TOWNHOMES SHORT PLAT
10839-SE 173RD STREET
RENTON, WA 98055
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CITY OF
RENTON
10839-SE 173RD STREET
RENTON, WA 98055 ® -~-.......
~
DETAILS
Meyer Townhomes Short Plat -DRAFT Technical Information Report
The Concept Group
Appendix D
Flow Control, Water Quality
and Infiltration Design
September 2008
Appendices
C.1.3 APPLICATION OF FLOW CONTROL BMPS
FIGURE C.1.3.A FLOWCHART FOR DETERMINING APPLICATION OF FLOW CONTROL BMPS
Is the project on a site/lot Yes . Is it feasible and
smaller than 22,000 square feet? ~ applicable to
implement full Yes No further BMPs
Apply one or more of the following to impervious area dispersion for the required. Note:
:.i: 10% of site/lot for s/tWlot sizes <11,000 sf and::. 20% of roof area as per Any proposed
site/lot for site/lot sizes between 11,000 and 22,000 sf (For Section C.2.1? connection of roof
projects located in critical aquifer recharge areas these Noy downspouts to
impervious area amounts double): local drainage
1. Limited Infiltration (Section C.2.3)
Is it feasible
system must be
2. Basic Dispersion (Section C.2.4) via pertorated
3. Rain Garden (Section C.2.5) and applicable pipe connection
4. Permeable Pavement (Section C.2.6) No to implement Yes . per Section -full Infiltration 5. Rainwater Harvesting (Section C.2.7) " C.2.11.
No 6. Vegetated Roof (Section C.2.8) of the roof
7. Reduced Impervious Service Credit (Section C.2.9) runoff as per
8. Native Growth Retention Credit (Section C.2.1 O) Section C.2.2?
I
Notes:
No flow control BMPs are required tor new pervious surfaces.
Water aualitv lm.....,.cts are adeauatelv addressed with the above flow control BMPs.
The project must be a site/lot I Is it feasible
greater than or equal to 22,000 square feet? I and applicable to
implement full Yes No further BMPs dispersion on required. Note: all target Jmpervlous Any proposed surface as per connection of roof
One or more of the following BMPs must be implemented Section C.2.1? downspouts to
for target Impervious surface not addressed with full No f local drainage
dispersion or with full infiltration of roof runoff:
Is it feasible and system must be
1. Full Infiltration {Section C.2.2)
No applicable to implement via perforated
2. Limited lnflltratlon (Section C.2.3)
full lnflltratlon of the pipe connection
3. Basic Dispersion (Section C.2.4)
roof runoff as per per Section
4. Rain Garden (Section C.2.5)
Section C.2.2? C.2.11.
5. Permeable Pavement (Section C.2.6)
6. Rainwater Harvesting (Section C.2.7) Yesy
7. Vegetated Roof (Section C.2.8) Is there any remaining target
8. Reduced Impervious Service Credit (Section C.2.9) Yes Impervious surface not addressed No
9. Native Growth Retention Credit (Section C.2.1 OI with full dispersion or with full
I infiltration of roof runoff?
Note:
Flow control BMPs are required for all new pervlous surface when it exceeds 35,000 sf. Flow control BMPs must be applied in the
following order of preference:
1. The feasibility and applicability of full dispersion as detailed in Section C.2.1 must be evaluated for all new pervious surfaces.
2. For those pervious surfaces not addressed in Requirement 1 above, one or more of the following BMPs must be implemented:
Basic Dispersion (Section C.2.4)
Rain Garden /Section C.2.5)
Note:
The following extra water quality provisions must be implemented if the project results in 5,000 sf or more of additional pollution
generating Impervious surlace from which runoff is not fully dispersed in accordance with Section C.2.1:
1. Reduce existing or proposed pollution generating impervious surface so that the 5,000 sf threshold is not triggered.
2. Provide water quality facilities designed by a licensed civil engineer in accordance with Section 1.2.8 of the SWDM.
2005 Surface Water Design Manual -Appendix C l/24/2005
C-17
SECTION C.2 FLOW CONTROL BMPs
6"
6"
12"
1/24/2005
FIGURE C.2.2.A TYPICAL TRENCH INFILTRATION SYSTEM
PLAN VIEW
NTS ,-4" rigid or 6" flexible
/ perforated pipe
(-······························· ········. / ·····:
----------. --· ..... --------·---------....... -. --.
roof
drain
infiltration trench sump w/solid lid
.Y. % ,..., ,,.
PLAN VIEW
NTS
4" rigid or 6" flexible
pertorated pipe
................ ............ . -. ---... -,.
'
overflow
splash block
fu•' '
: o a c=:'.:::::===:Jiiiiil~:::::==;::::;;::::µ::===::;-. bi• ' " .. . o. " ~m·,n so· . I : <....lo_ washed rock '-;lo. ·:-:.,:;, :::• e :..; ~ 11 • · min._
i" ~ 1 1/2"-3/4" ---:--.:::.·;';---'cc' '-.J O 6 c.:,, .'): min ~+.:··.,_._._ ... ", =--'-"--"
filter fabric
SECTION A
NTS
C-42
2005 Surface Water Design Manual -Appendix C
David and Jeff Meyers
Meyer Townhomes Short Plat
10839-SE 173RD ST
Renton, WA 98055
House #1
Orivewav#1
House#2
Drivewav#2
House #3
Drivewav #3
Shoulder Improvement
Access Road
Total Roof Area
Total PGIS 1
Total Pervious Area
Total Proiect Size
PGIS' =
Area infiltrated =
Impervious Surface =
Total Project (ac) =
Impervious Area (Sq Ft)
Existina Pronosed
1,278
1,278
-
11,445
12,723
4,280 sq ft
8,142 sqft
8,142 sq ft
0.29
1,174
240
1,410
240
1,278
700
1,450
1,650
3,862
4,280
4,581
12 723
Infiltration Bottom Area, SF
: ' ' .· oer KCSWM for medium sand
.· .. .. Bottom Area =
. 60 SF/ 1000 SF
85
99
119
KCRTS INPUT tEXISTING CONDITION/
TILL Grass 0.26 ACRE
IMPERVIOUS 0.03 ACRE
TOTAL 0.29 ACRE
100-year IH!!Bk flow 0.069 cfs
KCRTS INPUT (DEVELOPED CONDITION)
TILL GRASS 0.105 ACRE
IMPERVIOUS 0.187 ACRE
Infiltrated (not in model) ACRE
TOTAL 0.29 ACRE
100-year peak flow 0.111 cfs
1100-year peak flow increase 0.042 Jets
Meyer Townhomes Short Plat
KCRTS Flow Rate Data
September 26, 2008
Existing Condition
Flow Frequency Analysis
Time Series File:meyerexisting.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates--------Flow Frequency Analysis-------
Flow Rate Rank Time of Peak
(CFS)
0.030 4 2/09/01 2:00
0. 018 6 1/05/02 16:00
0.038 2 2/27 /03 7:00
0.012 8 8/26/04 2:00
0.018 7 1/05/05 8:00
0.031 3 1/18/06 16:00
0. 02 9 5 11/24/06 3:00
0.069 1 1/09/08 6:00
Computed Peaks
Developed Condition
Flow Frequency Analysis
Time Series File:meyerdev.tsf
Project Location:Sea-Tac
---Annual Peak Flow Rates---
Flow Rate Rank Time of Peak
(CFS)
0.055 6 2/09/01 2:00
0.045 8 1/05/02 16:00
0.066 3 2/27 /03 7:00
0.049 7 8/26/04 2:00
0.059 4 10/28/04 16:00
0.059 5 1/18/06 16:00
0.072 2 10/26/06 0:00
0 .111 1 1/09/08 6:00
Computed Peaks
--Peaks Rank Return Prob
(CFS) Period
0.069 l 100.00 0.990
0.038 2 25.00 0.960
0.031 3 10.00 0.900
0.030 4 5.00 0.800
0.029 5 3.00 0.667
0.018 6 2.00 0.500
0.018 7 1. 30 0.231
0.012 8 1.10 0. 091
0.059 50.00 0.980
-----Flow Frequency Analysis-------
--Peaks Rank Return Prob
(CFS) Period
0.111 1 100.00 0.990
0 .072 2 25.00 0. 960
0.066 3 10.00 0.900
0.059 4 5.00 0.800
0.059 5 3.00 0.667
0.055 6 2.00 0.500
0.049 7 1. 30 0.231
0.045 8 1.10 0.091
0.098 50.00 0.980
Meyer Townhomes Short Plat -DRAFT Technical Information Report
The Concept Group
Appendix E
Erosion Control
September 2008
Appendices
SW1/4 OF SEl/4, SEC. 29-T23N-A5E, W.M. SEOlENCE OF CONSTRUCllQN,
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:t F1.AC a£IMolC IM1S .tfl) PROPERTY IMS.
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KING COUNTY, WASHINGTON. SURFACE WATER DESIGN MANUAL, APPENDIX C
C.3 EROSION AND SEDIMENT CONTROL (ESC) MEASURES
This section presents the specifications for the kinds of the ESC measures applicable to small project sites
as allowed by the County's ESC Standan/s (Detached Appendix D of the King County Surface Water
Design Manua[). For projects in Small Project Drainage Review, these measures may be used if no more
than 3 acres of soil will be disturbed by the project. Other ESC measures may be allowed or required by
DOES if these are inappropriate for the project or fail to contain sediment on the project site. A
description of other measures and a more detailed description of those included here can be found in the
ESC Standards. Projects that disturb 3 acres or more of soil will require an ESC plan developed by a
civil engineer under a Targeted Drainage Review.
Intent of ESC Measures
The intent of ESC measures is to prevent, to the maximum extent practicable, the transport of sediment
and other construction-related pollutants to streams, wetlands, lakes, drainage systems, and adjacent
properties during and after construction. Erosion of disturbed areas on construction sites can result in
excessive sediment transport to adjacent properties and to surface waters. This sediment can result in
major adverse impacts, such as flooding due to obstructed drainage ways, smothering of salmonid
spawning beds, creation of algal blooms in lakes, and violation of State water quality standards for
turbidity. In addition to sediment, other construction-related pollutants can be generated by uncovered
waste materials, stockpiles, and demolition debris; de-watering; maintenance and operation of heavy
equipment; chemical spills; oil spills; placement of concrete; and application of fertilizers and pesticides.
Such pollutants can be toxic to both fish and humans and may violate State water quality standards and the
prohibited discharges section of KCC 9.12. Stabilization of the site after construction and prior to the wet
season is also important to preventing these impacts.
Organization of Section C.3
The ESC measures in this section are divided into two categories, those used during construction and
those used after. Those measures used during construction are referred to as temporary ESC measures
while those used after construction are referred to as permanent or final stabilization measures. Thus, the
section is organized as follows:
• Section C.3.1, "Temporary ESC" (p. C-79)
• Section C.3.2, "Final Stabilization" (p. C-90)
C.3.1 TEMPORARY ESC
Temporary ESC measures are used during construction to minimize the amount of sediment mobilized and
trap any mobilized sediment before it leaves the project site. This section presents the requirements and
specifications for those temporary ESC measures typically applied to projects in Small Project Drainage
Review. They include the following:
• "Stabilized Construction Entrance," Section C.3. 1. 1 (p. C-80)
• "Mulching," Section C.3.1.2 (p. C-81)
• "Nets and Blankets," Section C.3.1.3 (p. C-83)
• "Plastic Covering," Section C.3.1.4 (p. C-85)
• "Mark Clearing Limits/Minimize Clearing," Section C.3. 1.5 (p. C-86)
• "Silt Fence," Section C.3.1.6 (p. C-86)
• "Vegetated Strip," Section C.3.1.7 (p. C-88)
2005 Surface Water Design Manual-Appendix C 1/24/2005
C-79
SECTION C.3 EROSION AND SEDIMENT CONTROL (ESC) MEASURES
• "Triangular Silt Dike," Section C.3.1.8 (p. C-89)
• "Winter Stabilization," Section C.3.1.9 (p. C-90)
The above measures must be implemented as needed to prevent the discharge of sediment-laden water
from the construction site. Proposed measures must be shown on the small site ESC plan required to be
submitted with the small project drainage plans. Site-specific conditions during construction may require
additional measures as deemed necessary by ODES. As noted in Section C.3 above, other temporary ESC
measures found in Appendix O of the SWDM may be needed or may be more appropriate for the project
site as determined by ODES.
C.3.1.1 STABILIZED CONSTRUCTION ENTRANCE
Purpose
l/24/2005
Construction entrances are stabilized to reduce the amount of sediment transported onto paved roads by
motor vehicles or runoff by constructing a stabilized pad of quarry spa11s at the entrances to construction
sites.
Application
Construction entrances shall be stabilized wherever traffic will be leaving a construction site and traveling
on paved roads or other paved areas within 1,000 feet of the site.
Design and Installation Specifications
I. See Figure C.3.1.A for details.
2. A separation geotextile shall be placed under the spalls to prevent fine sediment from pumping up into
the rock pad. The geotextile shall meet the following standards:
Grab Tensile Strength (ASTM 04751) 200 psi min.
Grab Tensile Elongation (ASTM 04632) 30% max.
Mullen Burst Strength (ASTM 03786-SOa) 400 psi min.
AOS (ASTM 04751) 20-45 (U.S. standard sieve size)
3. Hog fuel (wood based mulch) may be substituted for or combined with quarry spalls in areas that will
not be used for permanent roads. The effectiveness of hog fuel is highly variable, but it has been used
successfully on many construction sites. It generally requires more maintenance than quarry spalls.
Hog fuel is not recommended for entrance stabilization in urban areas. The inspector may at any time
require the use of quarry spalls if the hog fuel is not preventing sediment from being tracked onto
pavement or if the hog fuel is being carried onto pavement. Hog fuel is prohibited in permanent
roadbeds because organics in the subgrade soils cause difficulties with compaction.
4. Whenever possible, the entrance shall be constructed on a firm, compacted subgrade. This can
substantially increase the effectiveness of the pad and reduce the need for maintenance.
Maintenance
I. Quarry spalls (or hog fuel) shall he added if the pad is no longer in accordance with the specifications.
2. If the entrance is not preventing sediment from being tracked onto pavement, then alternative
measures to keep the streets free of sediment shall be used. This may include street sweeping, an
increase in the dimensions of the entrance, or the installation of a wheel wash. If washing is used, it
2005 Surface Water Design Manual-Appendix C
C-80
C.3.1 TEMPORARY ESC
shall be done on an area covered with crushed rock, and wash water shall drain to a sediment trap or
pond.
3. Any sediment that is tracked onto pavement shall be removed immediately by sweeping. The
sediment collected by sweeping shall be removed or stabilized onsite. The pavement shall not be
cleaned by washing down the street, except when sweeping is ineffective and there is a threat to public
safety. If it is necessary to wash the streets, a small sump must be constructed. The sediment would
then be washed into the sump where it can be controlled and discharged appropriately.
4. Any quarry spalls that are loosened from the pad and end up on the roadway shall be removed
immediately.
FIGURE C.3.1.A STABILIZED CONSTRUCTION ENTRANCE
AS PER KING COUNTY ROAD STANDARDS,
DRIVEWAYS SHALL BE PAVED TO THE EDGE
OF R-0-W PRIOR TO INSTALLATION OF THE
CONSTRUCTION ENTRANCE TO AVOID
DAMAGING OF THE ROADWAY
INSTALL DRIVEWAY CULVERT IF THERE
IS A ROADSIDE DITCH PRESENT, AS
PER KING COUNTY ROAD STANDAROS
4" -8" QUARRY SPALLS -
GEOTEXTILE-
12" MIN. THICKNESS
C.3.1.2 MULCHING
Purpose
I
IT IS RECOMMENDED THAT THE
ENTRANCE BE CROWNED SO THAT
RUNOFF DRAINS OFF THE PAD
The purpose of mulching soils is to provide immediate temporary protection from erosion. Mulch also
enhances plant establishment by conserving moisture, holding fertilizer, seed, and topsoil in place, and
moderating soil temperatures. There is an enormous variety of mulches that may be used. Only the most
common types are discussed in this section.
Conditions of Use
As a temporary cover measure, mulch should be used:
1. On disturbed areas that require cover measures for less than 30 days
2. As a cover for seed during the wet season and during the hot summer months
3. During the wet season on slopes steeper than 3H:IV with more than 10 feet of vertical relief.
2005 Surface Water Design Manual -Appendix C 1/24/2005
C-81
I
SECTION C.3 EROSION AND SEDIMENT CONTROL (ESC) MEASURES
Mulch
Material
Straw
Wood Fiber
Cellulose
Compost
Hydraulic
Matrices
Design and Installation Specifications
For mulch materials, application rates, and specifications, see Table C.3.1.A. Note: Thicknesses may be
increased for disturbed areas in or near critical areas or other areas highly susceptible to erosion.
Maintenance Standards
I. The thickness of the mulch cover must be maintained.
2. Any areas that experience erosion shall be re-mulched and/or protected with a net or blanket. If the
erosion problem is drainage related, then the drainage problem shall be assessed and alternate
drainage such as interceptor swales may be needed to fix the problem and the eroded area re-mulched.
TABLE C.3.1.A MULCH STANDARDS AND GUIDELINES
Quality Standards Application Remarks
Rates
Air-dried; free from 2"-3" thick; 2-3 Cost-effective protection when applied with adequate
undesirable seed and bales per 1 000 st thickness. Hand-application generally requires greater
coarse material or 2-3 tons per acre thickness than blown straw. Straw should be crimped to
avoid wind blow. The thickness of straw may be
reduced by halt when used in conjunction with seeding.
No growth inhibiting Approx. 25-30 lbs Shall be applied with hydromulcher. Shall not be used
factors per 1000 sf or without seed and tackifier unless the application rate is
1000-1500 lbs per at least doubled. Some wood fiber with very long fibers
acre can be effective at lower application rates and without
seed or tackifier.
No visible water or dust 2" thick min.; More effective control can be obtained by increasing
during handling. Must approx. 100 tons thickness to 3". Excellent mulch for protecting final
be purchased from per acre (approx. grades until landscaping because it can be directly
supplier with Solid 800 lbs per cubic seeded or tilled into soil as an amendment. Sources for
Waste Handling Permit. yard) compost are available from the King County Commission
for Marketing Recyclable Materials at (206) 296-4439.
This mulch category Apply at rates from The BFM shall not be applied immediately before, during
includes hydraulic 3,000 lbs per acre or immediately after rainfall so that the matrix will have
(Bonded Fiber slurries composed of to 4,000 lbs per an opportunity to dry for 24 hours after installation.
Matrix) wood fiber, paper fiber acre and based on Application rates beyond 2,500 pounds may interfere
or a combination of the manufacturers with germination and are not usually recommended for
two held together by a recommendations turf establishment. BFM is generally a matrix where all
binding system. The fiber and binders are in one bag, rather than having to
BFM shall be a mixture mix components from various manufacturers to create a
of long wood fibers and matrix. BFMs can be installed via helicopter in remote
various bonding agents. areas. They are approximately $1,000 per acre cheaper
to install.
Chipped Site Average size shall be 2" minimum This is a cost-effective way to dispose of debris from
Vegetation several inches. thickness clearing and grubbing, and it eliminates the problems
associated with burning. Generally, it should not be
used on slopes above approx. 10% because of its
tendency to be transported by runoff. It is not
recommended within 200 feet of surface waters. If
seeding is expected shortly after mulch, the
decomposition of the chipped vegetation may tie up
nutrients important to grass establishment.
l/24/2005 2005 Surface Water Design Manual -Appendix C
C-82
C.3.1.3 NETS AND BLANKETS
Purpose
C.3.1 TEMPORARY ESC
Erosion control nets and blankets are intended to prevent erosion and hold seed and mulch in place on
steep slopes and in channels so that vegetation can become well established. In addition, some nets and
blankets can be used to permanently reinforce turf to protect drainage ways during high flows. Nets are
strands of material woven into an open, but high-tensile strength net (for example, jute matting). Blankets
are strands of material that are not tightly woven, but instead form a layer of interlocking fibers, typically
held together by a biodegradable or photodegradable netting (for example, excelsior or straw blankets).
They generally have lower tensile strength than nets, but cover the ground more completely. Coir
(coconut fiber) fabric comes as both nets and blankets.
Conditions of Use
Erosion control nets and blankets should be used:
1. For permanent stabilization of slopes 2H: 1 V or greater and with more than 10 feet of vertical relief.
2. In conjunction with seed for final stabilization of a slope, not for temporary cover. However, they
may be used for temporary applications as long as the product is not damaged by repeated handling.
In fact, this method of slope protection is superior to plastic sheeting, which generates high-velocity
runoff.
3. For drainage ditches and swales (highly recommended). The application of appropriate netting or
blanket to drainage ditches and swales can protect bare soil from channelized runoff while vegetation
is established. Nets and blankets also can capture a great deal of sediment due to their open, porous
structure. Synthetic nets and blankets may be used to permanently stabilize channels and may provide
a cost-effective, environmentally preferable alternative to riprap.
Design and Installation Specifications
1. See Figure C.3.1.B and Figure C.3.1.C for typical orientation and installation of nettings and blankets.
Note: Installation is critical to the effectiveness of these products. If good ground contact is not
achieved, runoff can concentrate under the product, resulting in significant erosion.
2. Jute matting must be used in conjunction with mulch. Excelsior, woven straw blankets, and coir
(coconut fiber) blankets may be installed without mulch. There are many other types of erosion
control nets and blankets on the market that may be appropriate in certain circumstances. Other
types of products will have to be evaluated individually. In general, most nets (e.g., jute matting)
require mulch in order to prevent erosion because they have a fairly open structure. Blankets typically
do not require mulch because they usually provide complete protection of the surface.
3. Purely synthetic blankets are allowed but shall only be used for Jong-term stabilization of waterways.
The organic blankets authorized above are better for slope protection and short-term waterway
protection because they retain moi~ture and provide organic matter to the soil, substantially improving
the speed and success of re-vegetation.
Maintenance Standards
1. Good contact with the ground must be maintained, and there must not be erosion beneath the net or
blanket.
2. Any areas of the net or blanket that are damaged or not in close contact with the ground shall be
repaired and stapled.
3. If erosion occurs due to poorly controlled drainage, the problem shall be fixed and the eroded area
protected.
2005 Surface Water Design Manual -Appendix C 1/2412005
C-83
SECTION C.3 EROSION AND SEDIMENT CONTROL (ESC) MEASURES
FIGURE C.3. l.B WATERWAY INSTALLATION
DO NOT STRETCH BLANKETS/MATTINGS TIGHT -
ALLOW THE ROLLS TO MOLD TO ANY IRREGULARITIES
SLOPE SURFACE SHALL BE SMOOTH BEFORE
PLACEMENT FOR PROPER SOIL CONTACT
ANCHOR, STAPLE, AND INSTALL CHECK
SLOTS AS PER MANUFACTURER'S
RECOMMENDATIONS
AVOID JOINING MATERIAL IN THE
CENTER OF THE DITCH
LIME, FERTILIZE AND SEED
BEFORE INST.A.LlATION
MIN. 4" OVERLAP
MIN. 6' OVERLAP
FIGURE C.3.1.C SLOPE INSTALLATION
SLOPE SURFACE SHALL BE SMOOTH BEFORE
PLACEMENT FOR PROPER SOIL CONTACT
STAPLING PATIERN AS PER
MANUFACTURER'S RECOMMENDATIONS
DO NOT STRETCH BLANKETS/MATTINGS TIGHT -
ALLOW THE ROLLS TO MOLD TO p.JfY IRREGULARITIES
FOR SLOPES LESS THAN 3H:1V, ROLLS
MAY BE PLACED IN HORIZONTAL STRIPS
1/2412005
C-84
ANCHOR IN 6"x6" MIN. TRENCH
AND STAPLE AT 12" INTERVALS
LIME, FERTILIZE AND SEED BEFORE INSTALLATION.
PLANTING OF SHRUBS, TREES, ETC. SHOULD OCCUR
AFTER INSTALLATION.
2005 Surface Water Design Manual -Appendix C
C.3.l TEMPORARY ESC
C.3.1.4 PLASTIC COVERING
Purpose
Plastic covering provides immediate, short-term erosion protection to slopes and disturbed areas.
Conditions of Use
I. Plastic covering may be used on disturbed areas that require cover measures for less than 30 days.
2. Plastic is particularly useful for protecting cut and fill slopes and stockpiles. Note: The relatively
rapid breakdown of rrwst polyethylene sheeting makes it unsuitable for long-term applications.
3. Clear plastic sheeting may be used over newly-seeded areas to create a greenhouse effect and
encourage grass growth. Clear plastic should not be used for this purpose during the summer months
because the resulting high temperatures can kill the grass.
4. Due to rapid runoff caused by plastic sheeting, this method shall not be used upslope of areas that
might be adversely impacted by concentrated runoff. Such areas include steep and/or unstable slopes.
Note: There have been many problems with plastic, usually attributable to poor installation and
maintenance. However, the material itself can cause problems, even when correctly installed and
maintained, because it generates high-velocity runoff and breaks down quickly due to ultraviolet
radiation. In addition, if the plastic is not completely removed, it can clog drainage system inlets and
outlets. It is highly recommended that alternatives to plastic sheeting be used whenever possible and that
its use be limited.
Design and Installation Specifications
I. See Figure C.3.1.D for details.
2. Plastic sheeting shall have a minimum thickness of 0.06 millimeters.
3. If erosion at the toe of a slope is likely, a gravel berm, riprap, or other suitable protection shall be
installed at the toe of the slope in order to reduce the velocity of runoff.
PROVIDE ENERCY D1SSIPAT10N
AT TOE WHEN NEEDED
2005 Surface Water Design Manual -Appendix C
FIGURE C.3.1.D PLASTIC COVERING
C-85
TIRES, SANDBAGS, a;t EQUI\IALENT
MAY BE USED TOWEK31iT PLASTIC
SEAMS BETWEEN SHEETS WST
OVERLAP A MINIMW OF 12" ANO
BE WEIGHTED OR TAPED
1/2412005
SECTION C.3 EROSION AND SEDIMENT CONTROL (ESC) MEASURES
Maintenance Standards for Plastic Covering
I. Tom sheets must be replaced and open seams repaired.
2. If the plastic begins to deteriorate due to ultraviolet radiation, it must be completely removed and
replaced.
C.3.1.5 MARK CLEARING LIMITS/MINIMIZE CLEARING
Purpose
Minimizing clearing is the most effective method of erosion control. Undisturbed vegetation intercepts
and slows rainwater. Plant roots hold soil in place, and dead vegetation on the ground acts as a mulch.
Applications
Clearing limits shall be marked and clearing minimized on any site where significant areas of undisturbed
vegetation will be retained.
Design Specifications
Minimizing clearing should be incorporated into the site design. Clearing limits must be marked on the
small site ESC plan. On the ground, clearing limits must be clearly marked with brightly colored tape or
plastic or metal safety fencing. If tape is used, it should be supported by vegetation or stakes, and should
be about 3 to 6 feet high and highly visible. Equipment operators should be informed of areas of
vegetation that are to be left undisturbed.
Maintenance
Fencing shall be inspected regularly and repaired or replaced as needed.
C.3.1.6 SILT FENCE
l/2412005
Purpose
Use of a silt fence reduces the transport of coarse sediment from a construction site by providing a
temporary physical barrier to sediment and reducing the runoff velocities of overland flow.
Conditions of Use
Silt fence may be used downslope of all disturbed areas. Silt fence is not intended to treat concentrated
flows, nor is it intended to treat substantial amounts of overland flow.
Design and Installation Specifications
I. See Figure C.3.1.E and Figure C.3.1.F for details.
2. The geotextile used must meet the standards listed below. A copy of the manufacturer's fabric
specifications must be available onsite.
AOS (ASTM D4751) 30-100 sieve size (0.60-0.15 mm) for slit film
50-100 sieve size (0.30-0.15 mm) for other fabrics
Water Permittivity (ASTM D4491) 0.02 sec·' minimum
Grab Tensile Strength (ASTM D4632) 180 lbs. min. for extra strength fabric
100 lbs. min. for standard strength fabric
Grab Tensile Elongation (ASTM D4632) 30% max.
Ultraviolet Resistance (ASTM D4355) 70% min.
2005 Surface Water Design Manual-Appendix C
C-86
C.3.1 TEMPORARY ESC
3. Standard strength fabric requires wire backing to increase the strength of the fence. Wire backing or
closer post spacing may be required for extra strength fabric if field performance warrants a stronger
fence.
4. Where the fence is installed, the slope shall be no steeper than 2H: 1 V.
5. If a typical silt fence (per Figure C.3.1.E) is used, the standard 4 x 4 trench may not be reduced as long
as the bottom 8 inches of the silt fence is well buried and secured in a trench that stabilizes the fence
and does not allow water to bypass or undennine the silt fence.
Maintenance Standards
I. Any damage shall be repaired immediately.
2. If concentrated flows are evident uphill of the fence, they must be intercepted and conveyed to a
sediment trap or pond.
3. It is important to check the uphill side of the fence for signs of the fence clogging and acting as a
barrier to flow and then causing channelization of flows parallel to the fence. If this occurs, replace
the fence or remove the trapped sediment.
4. Sediment must be removed when the sediment is 6 inches high.
5. If the filter fabric (geotextile) has deteriorated due to ultraviolet breakdown, it shall be replaced.
FIGURE C.3.1.E SILT FENCE
JOINTS IN FILTER FABRIC SHAU. BE SPLICED
AT POSTS. USE STAPLES, WIRE RINGS, OR
EQUIVALENT TO ATIACH FABRIC TO POSTS.
FILTER FABRIC ---
-lr:,--------:i,--
1 I 6' MAX. I ---------MINIMUM 4"x4" TRENCH //
LJ / \ BACKFILL TRENCH WITH
NATIVESOILOR:314~-1.5~ /
POST SPACING MAY BE INCREASED WASHED GRAVEL
TO 8' IF WIRE BACKING IS USED
2"x4~ WOOD POSTS, STEEL FENCE
NOTE: FILTER FABRIC FENCES SHALL BE POSTS, REBAR, OR EQUIVALENT
INSTALLED ALONG CONTOUR WHENEVER POSSIBLE
2005 Surface Water Design Manual -Appendix C
C-87
1/24/2005
SECTION C.3 EROSION AND SEDIMENT CONTROL (ESC) MEASURES
FIGURE C.3.1.F SILT FENCE INSTALLATION AND MAINTENANCE
Dig trench Toe-in-fabric Stake
Reinforce Monitor Maintain and clean
C.3.1.7 VEGETATED STRIP
1/24/2005
Purpose
Vegetated strips reduce the transport of coarse sediment from a construction site by providing a temporary
physical barrier to sediment and reducing the runoff velocities of overland flow.
Conditions of Use
Vegetated strips may be used downslope of all disturbed areas. Vegetated strips are not intended to treat
concentrated flows. nor are they intended to treat substantial amounts of overland flow.
Design and Installation Specifications
I. The vegetated strip shall consist of a 25-foot minimum width continuous strip of dense vegetation
with a permeable topsoil. Grass-covered. landscaped areas are generally not adequate because the
volume of sediment overwhelms the grass. Ideally, vegetated strips shall consist of undisturbed native
growth with a well-developed soil that allows for infiltration of runoff.
2. The slope within the strip shall not exceed 4H: 1 V.
3. The uphill boundary of the vegetated strip shall be delineated with clearing limits as specified in
Section C.3.1.5 (p. C-86).
2005 Surface Water Design Manual -Appendix C
C-88
C.3.1 TEMPORARY ESC
Maintenance Standards
I. Any areas damaged by erosion or construction activity shall be seeded immediately and protected by
mulch.
2. If more than 5 feet of the original vegetated strip width has had vegetation removed or is being eroded,
sod must be installed.
C.3.1.8 TRIANGULAR SILT DIKE
Purpose
Triangular silt dikes (TSDs) may be used as check dams, for perimeter protection, for temporary soil
stockpile protection, for drop inlet protection, or as a temporary interceptor dike. Silt dikes, if attached to
impervious surfaces with tack or other adhesive agent may also be used as temporary wheel wash areas, or
concrete washout collection areas.
Conditions of Use
I. May be used for temporary check dams in ditches.
2. May be used on soil or pavement with adhesive or staples.
3. TSDs have been used to build temporary sediment ponds, diversion ditches, concrete washout
facilities, curbing, water bars, level spreaders, and berms.
Design and Installation Specifications
I. TSDs must be made of urethane foam sewn into a woven geosynthetic fabric.
2. TSDs are triangular, 10 inches to 14 inches high in the center, with a 20-inch to 28-inch base. A 2-
foot apron extends beyond both sides of the triangle along its standard section of 7 feet. A sleeve at
one end allows attachment of additional sections as needed
3. Install TSDs with ends curved up to prevent water from flowing around the ends
4. Attach the TSDs and their fabric flaps to the ground with wire staples. Wire staples must be No. 11
gauge wire or stronger and shall be 200 mm to 300 mm in length.
5. When multiple units are installed, the sleeve of fabric at the end of the unit shall overlap the abutting
unit and be stapled.
6. TSDs must be located and installed as soon as construction will allow.
7. TSDs must be placed perpendicular to the flow of water.
8. When used as check dams, the leading edge must be secured with rocks, sandbags, or a small key slot
and staples.
9. When used in grass-lined ditches and swales, the TSD check dams and accumulated sediment shall be
removed when the grass has matured sufficiently to protect the ditch or swale unless the slope of the
swale is greater than 4 percent. The area beneath the TSD check darns shall be seeded and mulched
immediately after dam removal.
Maintenance Standards
I. Triangular silt dikes shall be monitored for performance and sediment accumulation during and after
each runoff producing rainfall event. Sediment shall be removed when it reaches one half the height
of the silt dike.
2. Anticipate submergence and deposition above the triangular silt dike and erosion from high flows
around the edges of the dike/dam. Immediately repair any damage or any undercutting of the dike/dam.
2005 Surface Water Design Manual -Appendix C 1/24/2005
C-89
SECTION C.3 EROSION AND SEDIMENT CONTROL (ESC) MEASURES
C.3.1.9 WINTER STABILIZATION
Purpose
In order to minimize sediment-laden runoff, as much of the bare and disturbed portions of the project site
as possible should be covered during any period of precipitation. Once sediment is mobilized, it is much
more difficult to effectively control.
Application
All project sites require winter stabilization between October 1 and April 30 (the wet season).
Design Specifications
During the above time frame, slopes and stockpiles 3H: 1 V or steeper and with more than 10 feet of vertical
rise shall be covered if they are to remain unworked for more than 12 hours. Other disturbed areas shall be
covered or mulched according to Table C.3.1.A (p. C-82) if they are to remain unworked for more than two
days. Cover material sufficient to cover all disturbed areas shall be stockpiled on the site at the beginning of
the wet season. Areas that are to be left unworked during the winter shall be seeded prior to September 23.
Maintenance
The project site should be inspected weekly and immediately before, during, and after storms. Cover and
other erosion control measures shall be repaired and enhanced as necessary to prevent or minimize
sediment runoff and transport.
C.3.2 FINAL STABILIZATION
1/24/2005
Purpose
Final stabilization minimizes sediment-laden runoff from the project site after construction has been
completed.
Application
All sites require final stabilization prior to final construction approval.
Design Specifications
Prior to final construction approval. the project site shall be stabilized to prevent sediment-laden water
from leaving the project site after project completion. All disturbed areas of the project site shall be
vegetated or otherwise permanently stabilized. At a minimum, disturbed areas must be seeded and
mulched to ensure that sufficient cover will develop shortly after final approval. Mulch without seeding is
adequate for small areas to be landscaped before October 1.
All permanent surface water facilities (including catch basins, manholes, pipes, ditches, channels, flow
control facilities, and water quality facilities) impacted by sedimentation during construction must be
cleaned.
Maintenance
Permanent erosion control is the responsibility of the owner. The project site must be kept stabilized using
landscaping, mulch, or other measures to prevent sediment-laden water from leaving the project site and to
prevent sediment from being transported onto adjacent properties and roads.
2005 Surface Water Design Manual -Appendix C
C-90
Meyer Townhomes Short Plat -DRAFT Technical Information Report
The Concept Group
Appendix F
Maintenance Procedures
September 2008
Appendices
APPENDIX A MAJNTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO. 2-INFILTRATION FACILITIES
Maintenance Defect or Problem Conditions When Maintenance Is Needed Results Expected When
Component Maintenance Is Performed
Infiltration Pond Trash & Debris See "Detention Ponds" Table No. 1 See "Detention Ponds" Table No. 1
General
Poisonous Vegetation See "Detention Ponds" Table No. 1 See "Detention Ponds" Table No. 1
or Noxious Weeds
Contaminants and See "Detention Ponds" Table No. 1 See "Detention Ponds" Table No. 1
Pollution
Unmowed See "Detention Ponds" Table No. 1 See "Detention Ponds" Table No. 1
Grass/Ground Cover
Rodent Holes See "Detention Ponds~ Table No. 1 See "Detention Ponds" Table No. 1
Insects See "Detention Ponds~ Table No. 1 See "Detention Ponds" Table No. 1
Infiltration Pond Erosion See "Detention Ponds" Table No. 1 See "Detention Ponds" Table No. 1
Side Slopes
Infiltration Pond Tree Growth See "Detention Ponds" Table No. 1 See "Detention Ponds" Table No. 1
Emergency
Overflow Spillway
and Berms over 4
feet in height.
Infiltration Pond Rock Missing See "Detention Ponds" Table No. 1 See "Detention Ponds" Table No. 1
Emergency
Overflow Spillway
Infiltration Facility Sediment A percolation test pit (ponds) or test of facility Sediment is removed and/or facility
Storage Area indicates facility is only working at 90%.1 of its is cleaned so that infiltration system
designed capabilities. If two inches or more works according to design. Ponds
sediment is present, remove. are reseeded if necessary to control
erosion.
Infiltration Facility Sediment and Debris By visual inspection, little or no water flows Replaced gravel in rock fitter.
Rock Filters through filter during heavy rain storms.
(If Applicable)
Infiltration Facility Sump Filled with Any sediment and debris filling vault to 10% of Clean out sump to design depth.
Sump Sediment and Debris depth from sump bottom to bottom of outlet pipe
(If Applicable) or obstructing flow into the connector pipe.
Infiltration Facility Filled with Sediment Sediment and debris fill bag more than 1
/2 full. Replaced filter bag or redesign
Filter Bags and Debris system.
(If Applicable)
Infiltration Facility Sediment Remove when 6" or more. Sediment cleaned out to designed
Pre-settling Ponds pond shape and depth or sediment
and Vaults is removed from vault. Ponds are
reseeded if necessary to control
erosion.
Note: Sediment accumulation of more than 0.25 inches per year may indicate excessive erosion is occurring upstream of the facility or
that conveyance systems are not being properly maintained. The contributing drainage area should be checked for erosion problems or
inadequate maintenance of conveyance systems if excessive sedimentation is noted in an infiltration facility.
Check twice a year dun·ng first 2 years of operation; once a year thereafter. Clean manholes/catch basins, repair damaged inlets/outlets,
clean trash racks.
2005 Surface Water Design Manual -Appendix A 1/2412005
A-3
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO. 5-CATCH BASINS
Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When
Component Maintenance is performed
General Trash & Debris Trash or debris of more than % cubic foot which No Trash or debris located
(Includes Sediment) is located immediately in front of the catch basin immediately in front of catch basin
opening or is blocking capacity of the basin by opening.
more than 10%.
Trash or debris (in the basin) that exceeds 1/J the No trash or debris in the catch
depth from the bottom of basin to invert the basin.
lowest pipe into or out of the basin.
Trash or debris in any inlet or outlet pipe blocking Inlet and outlet pipes free of trash or
more than 1/3 of its height. debris.
Dead animals or vegetation that could generate No dead animals or vegetation
odors that could cause complaints or dangerous present within the 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.
Structure Damage to Corner of frame extends more than% inch past Frame is even with curb.
Frame and/or Top curb face into the street (If applicable).
Slab
Top slab has holes larger than 2 square inches Top slab is free of holes and cracks.
or cracks wider than Y.. inch (intent is to make
sure all material is running into basin).
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 Basin Cracks wider than 1/:. inch and longer than 3 feet, Basin replaced or repaired to design
Walls/Bottom any evidence of soil particles entering catch standards.
basin through cracks, or maintenance person
judges that structure is unsound.
Cracks wider than 1/:. inch and longer than 1 foot No cracks more than 1'4 inch wide at
at the joint of any inleVoutlet pipe or any the joint of inleUoutlet pipe.
evidence of soil particles entering catch basin
through cracks.
SettlemenU Basin has settled more than 1 inch or has rotated Basin replaced or repaired to design
Misalignment more than 2 inches out of alignment. standards.
Fire Hazard Presence of chemicals such as natural gas, oil No flammable chemicals present.
and gasoline.
Vegetation Vegetation growing across and blocking more No vegetation blocking opening to
than 10% of the basin opening. basin.
Vegetation growing in inlet/outlet pipe joints that No vegetation or root growth
is more than 6 inches tall and less than 6 inches present.
apart.
Pollution Nonflammable chemicals of more than % cubic No pollution present other than
foot per three feet of basin length. surface film.
Catch Basin Cover Cover Not in Place Cover is missing or only partially in place. Any Catch basin cover is closed
open catch basin requires maintenance.
Locking Mechanism Mechanism cannot be opened by on Mechanism opens with proper tools.
Not Working maintenance person with proper tools. Bolts into
frame have less than % inch of thread.
Cover Difficult to One maintenance person cannot remove lid after Cover can be removed by one
Remove applying 80 lbs. of lift; intent is keep cover from maintenance person.
sealing off access to maintenance.
Ladder Ladder Rungs Unsafe Ladder is unsafe due to missing rungs, Ladder meets design standards and
misalignment, rust, cracks, or sharp edges. allows maintenance person safe
access.
1/24/2005 2005 Surface Water Design Manual -Appendix A
A-6
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO. 5-CATCH BASINS
Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When
Component Maintenance Is performed
Metal Grates Unsafe Grate Grate with opening wider than 7/8 inch. Grate opening meets design
(If Applicable) Opening standards.
Trash and Debris Trash and debris that is blocking more than 20% Grate free of trash and debris.
of grate surface.
Damaged or Missing. Grate missing or broken member(s) of the grate. Grate is in place and meets design
standards.
NO. 6 -DEBRIS BARRIERS (E.G., TRASH RACKS)
Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When
Component Maintenance is Performed.
General Trash and Debris Trash or debris that is plugging more than 20% Barrier clear to receive capacity
of the openings in the barrier. flow.
Metal Damaged/Missing Bars are bent out of shape more than 3 inches. Bars in place with no bends more
Bars. than :Y.. inch.
Bars are missing or entire barrier missing. Bars in place according to design.
Bars are loose and rust is causing 50% Repair or replace barrier to design
deterioration to any part of barrier. standards.
NO. 7 -ENERGY DISSIPATERS
Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When
Component Maintenance is Performed.
External:
Rock Pad Missing or Moved Only one layer of rock exists above native soil in Replace rocks to design standards.
Rock area five square feet or larger, or any exposure
of native soil.
Dispersion Trench Pipe Plugged with Accumulated sediment that exceeds 20% of the Pipe cleaned/flushed so that it
Sediment design depth. matches design.
Not Discharging Visual evidence of water discharging at Trench must be redesigned or
Water Properly concentrated points along trench (normal rebuilt to standards.
condition is a "sheet flow" of water along trench).
Intent is to prevent erosion damage.
Perforations Plugged. Over 1;; of perforations in pipe are plugged with Clean or replace perforated pipe.
debris and sediment.
Water Flows Out Top Maintenance person observes water flowing out Facility musl be rebuilt or
of uDistributor" Catch during any storm less than the design storm or redesigned to standards.
Basin. its causing or appears likely to cause damage.
Receiving Area Over-Water in receiving area is causing or has No danger of landslides.
Saturated potential of causing landslide problems.
Internal:
Manhole/Chamber Worn or Damaged Structure dissipating flow deteriorates to 1h or Replace structure to design
Post. Baffles, Side of original size or any concentrated worn spot standards.
Chamber exceeding one square foot which would make
structure unsound.
2005 Surface Water Design Manual -Appendix A 1/24/2005
A-7
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO. 10-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 that exceeds 20% of the Pipe cleaned of all sediment and
diameter of the pipe. debris.
Vegetation Vegetation that reduces free movement of water All vegetation removed so water
through pipes. flows freely through pipes.
Damaged Protective coating is damaged; rust is causing Pipe repaired or replaced.
more than 50% deterioration to any part of pipe.
Any dent that decreases the cross section area Pipe repaired or replaced.
of pipe by more than 20%.
Open Ditches Trash & 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
design depth. sediment and debris so that it
matches design.
Vegetation Vegetation that reduces free movement of water Water flows freely through ditches.
through ditches.
Erosion Damage to See "Detention Ponds" Table No. 1 See ~Detention Ponds~ Table No. 1
Slopes
Rock Lining Out of Maintenance person can see native soil beneath Replace rocks to design standards.
Place or Missing (If the rock lining.
Applicable).
NO. 11 -GROUNDS (LANDSCAPING)
Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When
Component Maintenance is Performed
General Weeds Weeds growlng in more than 20% of the Weeds present in less than 5% of
(Nonpoisonous, not landscaped area (trees and shrubs only). the landscaped area.
noxious)
Safety Hazard Any presence of poison ivy or other poisonous No poisonous vegetation present in
vegetation landscaped area.
Trash or Litter Paper, cans, bottles, totaling more than 1 cubic Area clear of litter.
foot within a landscaped area (trees and shrubs
only) of 1,000 square feet.
Trees and Shrubs 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 Tree or shrub in place free of injury.
knocked over.
Trees or shrubs which are not adequately Tree or shrub in place and
supported or are leaning over, causing exposure adequately supported; remove any
of the roots. dead or diseased trees.
2005 Surface Water Design Manual -Appendix A 1/24/2005
A-9
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ F ACIL!TIES
NO. 12 -ACCESS ROADS
Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When
Component Maintenance is Performed
General Trash and Debris Trash and debris exceeds 1 cubic foot per 1,000 Roadway free of debris which could
square feet {i.e., trash and debris would fill up damage tires.
one standards size garbage can).
Blocked Roadway Debris which could damage vehicle tires (glass Roadway free of debris which could
or metal). damage tires.
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 Obstruction removed to allow at
12-foot width for a distance of more than 12 feet least a 12-foot access.
or any point restricting access to less than a 10-
foot width.
Road Surface Settlement, Potholes, When any surface defect exceeds 6 inches in Road surface uniformly smooth with
Mush Spots, Ruts deplh and 6 square feet in area. In general, any no evidence of settlement, potholes,
surface defect which hinders or prevents mush spots, or ruts.
maintenance access.
Vegetation in Road Weeds growing in the road surface that are more Road surface free of weeds taller
Surface than 6 inches tall and less than 6 inches tall and than 2 inches.
less than 6 inches apart within a 400-square foot
area.
Modular Grid Build-up of sediment mildly contaminated with Removal of sediment and disposal
Pavement petroleum hydrocarbons. in keeping with Health Department
recommendations for mildly
contaminated soils or catch basin
sediments.
Shoulders and Erosion Damage Erosion within 1 fool 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.
1/24/2005 2005 Surface Water Design Manual -Appendix A
A-10
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ F ACILIT!ES
NO, 22-BAFFLE OIL/WATER SEPARATOR
Maintenance Defect Condition When Maintenance is Needed Results Expected When
Component Maintenance is Performed.
Vault Area Monitoring Inspection of discharge water for obvious signs Effluent discharge from vault should
of poor water quality. be clear with out thick visible sheen.
Sediment Sediment depth in bottom of vault exceeds 6 No sediment deposits on vault
Accumulation inches in depth. bottom which would impede flow
through the vault and separation
efficiency.
Trash and Debris Trash and debris accumulation in vault Trash and debris removed from
Accumulation (floatables and non-floatables). vault, and inlet/outlet piping.
Oil Accumulation Oil accumulations that exceed 1 inch, at the Extract oil from vault by vactoring.
surface of the waler Disposal in accordance with state
and local rules and regulations.
Vault Structure Damage to Wall, Cracks wider than 1h-inch or evidence of soil Vault replaced or repaired to design
Frame. Bottom, particles entering the structure through the specifications.
and/or Top Slab cracks, or maintenance/inspection personnel
determines that the vault is not structurally
sound.
Damaged Pipe Joints Cracks wider than Yi-inch at the joint of any No cracks more than %-inch wide at
inleVoutlet pipe or any evidence of soil particles the joint of the inleVoutlet pipe.
entering the vault through the walls.
Baffles Damaged Baffles corroding, cracking, warping and/or Repair or replace baffles to
showing signs of failure as determined by specifications.
maintenance/inspection person.
lnlet/OuUet Pipes Trash and Debris Trash and debris accumulation in inlet/outlet Trash and debris removed from
Accumulation (floatables and non-floatables). vault, and inlet/outlet piping.
Damaged Pipes Inlet or oUllet piping damaged or broken and in Pipe repaired or replaced.
need of repair.
Access Cover Damaged/Not Cover cannot be opened. Corrosion/deformation Cover repaired to proper working
Working of cover. specifications or replaced.
Access Ladder Damaged Ladder is corroded or deteriorated, not Ladder replaced or repaired and
functioning properly, missing rungs, cracks, and meets specifications, and is safe to
misaligned. use as determined by inspection
personnel.
l/24/2005 2005 Surface Water Design Manual -Appendix A
A-18