05-0121 Stormwater Report 04012005r (,~
Mountain Meadows
Yeim, WA
Preliminary Drainage Report
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PRELIMINARY DRAINAGE REPORT
Yelm, Washington
April, 2005
Project Information
Project: Mountain Meadows
Prepared for: Henrietta Morey
Contact: Henrietta Morey
P:O. Box 202
Kapowsin, WA 98344
(360) 507-9300
Reviewing Agency
~ Jurisdiction: City of Yelm
Project Number:
Project Contact Jim Gibson
(360) 458-8438
Project Engineer
Prepared by: Olympic Engineering
1252 Devon Loop NE
Olympia, WA 98506
(360) 870-2561 FAX (360) 705-9361
Contact: Chris M. Merritt, P.E.
OES Project No.: 05002
File Name: 05002~pdr.doc
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PROJECT ENGINEERS CERTIFICATION: I hereby certify that this
Preliminary Drainage Report for the Mountain Meadowa Platin the City
of Yelm, Washington has been prepared by me or under my supervision
and meets the intent of the the WSDOE 1992 Stormwater Management
Manual, unless noted otherwise, and normal standards of engineering
practice. I understand that the jurisdiction does not and will not assume
liability for the sufficiency, suitability, or performance of drainage facilities
designed for this development.
I
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Table of Contents
APPENDICES
PART I STORM DRAINAGE REPORT ........................................................ 2 Appendix 1- Preliminary Drainage
• Calculations
SECTION 1- PROPOSED PROJECT DESCRIPTION ............................... 2
Appendix 2- Soils Report
SECTION 2- EXISTING CONDITIONS ..................................................... 3 Appendix 3- Vicinity Map
SECTION 3- INFILTRATION RATES / SOILS REPORT ..........................
3 Appendix 3- Drainage Basin Map
SECTION 4- WELLS AND SEPTIC SYSTEMS ......................................... 4
SECTION 5- FITEL TANKS ........................................................................ 4
SECTION 6- SUB-BASIN DESCRIPTION ................................................. 4 .
SECTION 7- ANALYSIS OF 100-YEAR, FLOOD ..............................:........ 4
SECTION 8- AESTHETIC CONSIDERATIONS FOR FACILITIES......... 5
SECTION 9- DOWNSTREAM AIVALYSIS ................................................. 5
SECTION 10 -COVENANTS, DEDICATIONS, EASEMENTS ................... 5
SECTION 11-ARTICLES OF INCORPORATION ....................................... 5
PART II EROSION CONTROL REPORT ....................................................6
SECTION 1- CONSTRUCTION SEQUENCE AND PROCEDUR,E .......... 6
SECTION 2- TRAPPING SEDIMENT ........................................................ 6
SECTION 3- PERMANENT EROSION CONTROL ................................... 7 '
SECTION 4- GEOTECHIVICAL ANALYSIS AND REPORT ..................... 7
SECTION 5- INSPECTION SEQUENCE ................................................... 7
SECTION 6- CONTROL OF POLLUTANTS .............................................. 8
PART III MAINTENANCE PLAN ...........................................:....................9
SECTION 1- REQUIRED MAINTENANCE ............................................... 9
SECTION 2 - RESPONSIBLE ORGADIIZATION ......................................18
SECTION 3- VEGETATION MANAGEMENT PLAN ..............................18
SECTION 4 - SOUR.CE CONTROL ............................................................18
ii
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PART I STORM DRAINAGE REPORT
SECTION 1 -PROPOSED PROJECT DESCRIPTION
Prepared for:
Contact:
Henrietta Morey
Henrietta Morey
P.O. Box 202
Kapowsin, WA 98344
(360) 507-9300
Parcel Number:
~ Total Site Area:
Zoned:
Site Address:
Required Permits:
, Section, Township, Range:
Project Overview
~
21713310400,21713310401,21713310402
4.88 Acres
R-6
8812 Burnett Road SW
Yelm, WA 98597
Grading, Utility, Building, etc.
Section 13
Township 17 North
Range 1 East, W.M.
The project site is located adjacent to Burnett Road in Yelm. The applicant
proposes to construct a new public roadway through the parcel and connect to the
road stub to the south; improve the Burnett Road frontage with roadway
widening, a sidewalk, and a planter strip; and to install utility services to serve 23
single family lots. Access to the proposed lots will be from the new public
roadway.
The development will be constructed in one phase. Construction will include
clearing and grading of the site, storm drainage improvements, underground
utilities, and paving. City of Yelm sanitary sewer and water mains will be
extended into the site to provide services to the residential lots. "
Stormwater facilities will be constructed that consist of a proposed biofiltration
swale and a wetvault for storm water treatment and an infiltration pond for
storage and infiltration of stormwater runoff created by the new development. For
stormwater design purposes, the proposed development has been subdivided into
three drainage sub-basins (see preliminary calculations in Appendix).
Stormwater Treatment:
A proposed wetvault will provide treatment for stormwater runoff from Basin `A'
(on-site roadway) and a proposed biofiltration swale will provide treatment for
Basin `B'. The proposed biofiltration swale and wetvault exceeds the minimum
required surface area per the DOE manual. See Preliminary Drainage
Calculations in Appendix.
Stormwater Storage:
All stormwater runoff from the new roadways will be collected in a series of catch
basins and conveyed to the biofiltration swale or wetpond for treatment.
Discharge from the biofiltration swale and wetpond flow into an infiltration pond
for stormwater detention and infiltration to groundwater. The proposed
stormwater pond exceeds the minimum storage requirements per the DOE
manual. See Preliminary Drainage Calculations in Appendix.
Roof Runoff:
Roof runoff from each residential home will be tightlined to inclividual lot
infiltration drainrock dxywells. The drywells shall be sized per Table 82 in the
DDECM using a soil hydrologic Group "A" classification.
SECTION 2 -EXISTING CONDITIONS
The project site contains a duplex residence with a barn. The home will remain
and the barn will be demolished. Site relief is gently sloping 2-3% east to west,
varying from an elevation of 340' at the northeast property corner to 328' at the
southwest corner. Site vegetation consists of low cut pasture grasses. The project
site is bounded by single-family residential property to the east, west, and north,
and a recently approved preliminary plat for a single family development to the
south.
See Section 6 for description of off-site drainage to the property, if any.
There appear to be no creeks, lakes, ravines, gullies, or springs on-site. There
appe"ar to be no drains, channels, or swales located within the project site, or
immediately adjacent to the proposed development.
The project site is located.in an aquifer sensitive area based on review of Thurston
County Comprehensive Plan Map M-8. This project will comply with the
stormwater treatment requirements of the DDECM.
SECTION 3-INFILTRATION RATES / SOILS REPORT
.. _ _
~ - The Soil -Coriservation Service (SCS) soil survey of Thurston County classifies the
on-site soils as Spanaway Gravelly Sandy Loam (Hydrologic Group A). Soil
testing confirmed the Spanaway series classification.
Two test pits were excavated by backhoe to a maximum depth of 144"• below
existing grade. Soils were irispected by entering and visually logging each test pit
to a depth of four feet. Soils beyond four feet were inspected by examining
backhoe tailings. One double ring infiltration test was completed with a result of
82"/hr. A 20"/hr rate will be used for design. Test pit soil log data sheets and
infiltration test results are included in the Appendix of this report.
SECTION 4-WELLS AND SEPTIC SYSTEMS
One on-site well was found during our site investigation of the proposed plat
development and it will be abandoned during development.
Two wells within 200-feet of the project boundaries were found to the east and
southwest, however, it appears the 100-foot protective radii's fall outside this
project's boundaries.
Water and sanitary sewer services for the proposed project will be provided by the
City of Yelm.
A septic system currently serves the existing home. This will be abandoned per ~~
Department of Health standards during development.
SECTION 5 -FUEL TANKS
No fuel tanks were located during our site inspection or soils work. The latest
"LUST" list (Leaking Underground Storage Tank) was reviewed and no listing for
the subject site was found.
SECTION 6 - SUB-BASIN DESCRIPTION
The project site is located within the Nisqually River Drainage Basin per the
Thurston County Geodata Center. From our site visit there were no signs of
existing drainage swales or channels on the proposed property. There did not
appear to be a significant amount of off-site runoff onto the site from the adjacent
north, east, and south properties.
Hazardous material handling or transportation is not expected in the area
tributary to the on-site detention facility.
SECTION 7-ANALYSIS OF 100-YEAR FLOOD
The proposed site does not lie adjacent to or contain a stream on-site, therefore, it
has_not been identified.as a 100-year flood hazard area.
SECTION 8-AESTHETIC CONSIDEFtATIONS FOR FACILITIES
All disturbed pervious areas including the storm drainage tract and open space
area will be vegetated and landscaped.
SECTION 9 -DOWNSTREAM ANALYSIS
Preliminary calculations for the project stormwater treatment and storage
systems are included in the Appendix of this report. ,
All stormwater runoff generated by site development will be treated, stored, and
infiltrated on-site. In the event of a failure, storm water will overflow through the
catch basin rims and temporarily back onto the public roadway. Adjacent
properties should not be affected due to failure of the proposed stormwater system.
SECTION 10 -COVENANTS, DEDICATIONS, EASEMENTS
On-site drainage ~facilities will require routine ~maintenance. A maintenance
agreement will be prepared and finalized prior to final project approval. '
SECTION 11 -PROPERTY OWNERS ASSOCIATION ARTICLES OF INCORPORATION
In light of the residential nature of this project, special covenants covering
landscape, maintenance, signage, stormwater and site maintenance may be put in
place at the time of final platting. The Owner's and/or their representatives will
perform maintenance of these private storm drainage facilities.
PART II EROSION CONTROL REPORT
SECTION 1-CONSTRUCTION SEQUENCE AND PROCEDURE
Proposed development of the residential property will include site grading and
erosion control measures designed to contain silt and soil within the project
boundaries during construction until permanent erosion control is in place.
Erosion/sedimentation control will be achieved by a combination of
structuraUvegetative cover measures and construction practices tailored to fit the
site.
Best Construction Management Practices (BMP's) will be employed to properly
clear and grade the site and to schedule construction activities. Before any
construction begins on-site, erosion control facilities shall first be installed. The
planned construction sequence is as follows:
1. Install rock construction entrance. Use 4" to 8" diameter spalls with 12"
minimum depth.
2. Install filter fabric fencing, where appropriate.
3. Construct temporary sedimentation basins, if necessary.
4. Clear site (grubbing and rough grading).
5. During November 1 through March 31, all disturbed areas greater than 5,000
sf that are to be left un-worked for more than twelve (12) hours, shall be
stabilized by one of the following: mulch, sodding, or plastic covering.
6. Install underground utilities (cable, telephone, power, etc.).
7. If applicable, provide catch basin protection by installing filter fabric and hay
bales around all inlets to drainage system.
8. After paving is complete, install landscape, sod and/or seed, and mulch all
disturbed areas.
-~ 9. Maintain all erosion control facilities until the entire site is stabilized and silt
runoff ceases.
10. Designate an area for washing of equipment and concrete trucks to control the
runoff and eliminate entry into storm drainage systems.
SECTION 2 -TRAPPING SEDIMENT
A stabilized construction entrance shall be installed at the entrance to the
proposed plat to prevent vehicles from tracking soil away from the disturbed
areas. If sediment is tracked onto public roadways, sediment shall, on a daily
basis, be swept or shoveled from paved surfaces and not washed down into the
roadside storm drainage system.
The contractor shall not be allowed to leave disturbed areas greater than 5,000 sf
that are to be left un-worked for more than.twelve (12) hours uncovered during the
rainy season from November 1 through March 31. 1Vlulch, sodding or plastic
covering will be used to prevent erosion in these areas.
During construction, the contractor will also be required to install filter fabric
fencing as needed, per the erosion control plan and as directed by the engineer, or
City Inspector
SECTION 3-PERMANENT EROSION CONTROL 8~ SITE RESTORATION
` All disturbed areas will be paved, covered with a building or landscaped with
grass, shrubbery or trees. ~
SECTION 4-GEOTECHNICAL ANALYSIS AND REPORT
There are no slopes exceeding 15% on-site, therefore, a geotechnical analysis was
deemed unnecessary.
SECTION 5 -INSPECTION SEQUENCE
In addition to the normal City inspections, the Project Engineer shall inspect the
facilities related to storm water treatment, erosion control, storage and
conveyance during construction. At a minimum, the following items shall be
inspected at the time specified:
1. The erosion control facilities shall be inspected before the start of clearing
, and grading to ensure the following structures are in place:
a. Construction Entrance
b. Filter Fabric Fences
2. The conveyance systems will be inspected after construction of the facility,
but before the project is completed to ensure the following are in working
order:
a. Road Drainage Conveyance System
b. Biofiltration Swale
c. Wetvault
~ d. Infiltration Pond ~
3. The permanent site restoration measures should be inspected after
landscaping is completed.
A final inspection shall be performed to verify final grades, settings of structures
and all necessary information to complete Engineer's Construction Inspection
~ Report Form and Residential Agreement to maintain stormwater facilities. These
forms must be completed prior to final public works construction approval. ,
SECTION 6-CONTROL OF POLLUTANTS OTHER THAN SEDIMENTS
Washout from a concrete truck shall not be dumped into the storm drain, or onto
soil or pavement, which carries stormwater runoff. It can be dumped into a
designated area to be later backfilled or hardened and broken up for disposal into
a dumpster. The Contractor will be required to designate a wash down area for
equipment and concrete trucks.
PART III MAINTENANCE PLAN
SECTION 1 -REQUfRED MAINTENANCE "
The following pages contain maintenance needs for most of the components that are
part of your drainage system, as well as for some components that you may not have.
Let us know if there are any components that are missing from these pages. Ignore
the requirements that do not apply to your system. You should plan to complete a
checklist for all system components on the following schedule:
1.Monthly from November through April.
2.Once in late summer (preferably September).
3.After any major storm (use 1" in 24 hours as a guideline) items marked "S" only.
Using photocopies of these pages, check off the problems you looked for each time you
did an inspection. Add comments on problems found and actions taken. Keep these
"Checked" sheets in your files, as they will be used to write your annual report (due in
May). Some items do not need to be looked at every time an inspection is done. Use
the suggest frequency at the left of each item as a guideline for your inspection.
You may call the jurisdiction for technical assistance. Please do not hesitate to call,
especially if you are unsure whether a situation you have discovered may be a
problem. -
ATTACHIVIENT `A'
Inspection Period:
MAINTENANCE PROGRAM
COVER SHEET
Number of Sheets Attached:
Date Inspected:
Inspector's Signature:
~
ATTACHMENT "A": MAINTENANCE PROGFtAM
Maintenance Checklist for Conveyance Systems (Pipes, Ditches and Swales)
Frequency Drainage ~ Req'd Problem Conditions To Check For Conditions That Should Exist
System Feature
M.S. Pipes ~ Sediment & Accumulated sediment that Pipe cleaned of all sediment and
' debris exceeds 20% of the diameter debris.
of the pipe.
M ~ Vegetation Vegetation that reduces free All vegetation removed so water
movement of water through flows freely.
pipes.
A ~ Damaged Protective coating is Pipe repaiied or replaced.
(rusted, bent damaged, ruet ia causing
or crushed) more than 50% deterioration
to any part of pipe.
M ~ ~ Any dent that significantly Pipe repaired or replaced.
impedes flow (i.e., decreases
the cross section azea of pipe
by more then 20%).
M ~ Pipe has major cracks or Pipe repaired or replaced.
tears allowing groundwater
leakage.
M.S. Swales ~l Trash & Dumping of yard wastes such Remove trash and debris and
debris as grass clippings and dispose as prescribed by County
branches into swale. Waste Management Section.
Unsightly accumulation of
non-degradable materials
• such as glass, plastic, metal,
foam and coated paper.
M ~ Sediment Accumulated sediment that Swale cleaned of all sediment and
buildup exceeds 20% of the design debris so that it matches design.
depth.
M ~ Vegetation Grass cover is sparse and Aerate soils and reseed and mulch
not growing weedy or areas are bare areas. Maintain grass height
or over-grown overgrown with woody at a minimum of 6" for best
vegetation. stormwater treatment. R.emove
woody growth, recontour and
reseed as necessary.
M ~ Conversion Swale has been filled in or If possible, speak with homeowner
by home- blocked by shed, woodpile, and request that swale area be
owner to shrubbery, etc. ' restored. Contact County to
incompatible report problem if not rectified
use voluntarily.
A ~ Swale does Water stands in swale or A survey may be needed to check
not drain flow velocity is very slow. grades. Grades need to be in 1%
Stagnation occurs. range if poasible. If grade is less
than 1%, under drains may need
to be installed.
If you are unsure whether a problem exists, please contact the Jurisdiction and ask for technical assistance.
~
ATTACHMENT "A" (CONTINUED)
Maintenance Checklist for Catch Basins and Inlets
Frequency Drainage J Req'd Probiem Conditions To Check For Conditions That Should Exist
System Feature
M,S General ~ • Trash, Trash or debris in front of the No trash or debris located
debris, and catch basin opening is blocking immediately in front of catch
sediment capacity by more than 10%. basin opening. Grate is kept
in or on clean and allows water to
basin enter.
M ~ Sediment or debris (in the No sediment or debris in the
basin) that exceeda 1/3 the catch basin. Catch basin is
depth &om the bottom of basin dug out and clean.
to invert of the lowest pipe into
or out of the basin.
M,S ~ J Traeh or debris in any inlet or Inlet and outlet pipes free of
pipe blocking more than 1/3 of trash or debris.
its height.
M ~ Structural Corner of frame extends more Frame is even with curb.
damage to than 3/4 inch past curb face
frame into the street (if applicable).
andlor top
slab
M ~ Top slab has holes larger than 2 Top slab is free of holes and
square inches or cracks wider cracks.
than 1/4 inch (intent is to make
sure all material is running
into the basin).
M ~ Frame not sitting flush on top Frame is sitting flush on top
slab, i.e., separation of more slab.
than 3/4 inch of the &ame firom
the top slab.
A ~ Cracks in Cracks wider than 1/2 inch and Basin replaced or repaired to
basin longer than 3 feet, any evidence design standards. Contact a
walls/ of soil particles entering catch professional engineer for
bottom basin through cracks, or evaluation.
maintenance person judges
that structure is unsound.
A ~l Cracks wider than 1/2 inch and No cracks more than 1/4 inch
longer than 1 foot at the joint of wide at the joint of inlet/outlet
any inleUoutlet pipe or any pipe.
evidence of soil particles
' entering catch ba'sin through
cracks.
A ~ Settlement Basin has settled more than 1 Basin replaced or repaired to
/misalign- inch or has rotated more than 2 design standards. Contact a
ment inches out of alignment. professional engineer for
evaluation.
; ~
Frequency Drainage
System Feature J Req'd Problem
- Conditions To Check For Conditions That Should Exist
M,S ~ Fire hazazd Presence of chemicals such No color, odor, or sludge. Basin is
or other as natural gas, oil, and dug out and clean.
pollution gasoline. Obnoxious color,
odor, or sludge noted.
M,S J Outlet pipe is Vegetation or roots growing No vegetation or root growth
clogged with in inletloutlet pipe joints present.
vegetation that is more than six inches
tall and less than six inches
apart.
If you are unsure whether a problem exists, please contact the Jurisdiction and ask for technical assistance.
Comments: .
Kev A= Annual (March or April preferred)
M = Monthly (see schedule)
S = tlfter major storms
ATTACHMENT "A" (CONTINUED)
Maintenance Checklist for Grounds (Landscaping)
Frequency Drainage ~1 Problem Conditions to Check For ~ Conditiona That Should Exist
System
Feature
M General ~ Weeds Weeda growing in more than Weeds present in less than 5°/a of
(nonpoisonous) 20% of the landscaped area the landscaped area.
(trees and shrubs only).
M ~ Safety hazard Any presence of poison ivy or No poisonous vegetation or
other poisonous vegetation or insect nests present in
insect nests. landscaped area.
M,S ~l Trash or litter See Ponds Checklist. See Ponds Checklist.
M,S ~ Erosion of Noticeable rills are seen in Causes of erosion are identified
Ground Surface landscaped areas. and steps taken to slow
down/spread out the water.
Eroded areas are 5lled,
' contoured, and seeded.
A Treea and ~ Damage Limbs or parts of trees or Trim trees/shrubs to restore
shrubs shrubs that are split or shape. Replace trees/shrubs
broken which affect more with severe damage.
than 25% of the total foliage
of the tree or shrub.
M •1 Trees or shrubs that have Replant tree, inspecting for
been blown down or knocked injury to stem or roots. Repiace
over. if severely damaged.
A ~I Trees or shrubs which are Place stakea and rubber-coated
not adequately supported or ties around young trees/shruba
are leaning over, causing for support.
exposuie of the mots.
If you are unsure whether a pmblem eacists, please contact the Jurisdiction and aek for technical assistance.
Comments:
Kev
A= Annual (March or April preferred)
M = Monthly (see schedule)
S = After major storms '
ATTACHMENT "A" (CONTINUED)
Maintenance Checklist for Energy Dissipaters
Freq. Drainage ~ Problem Conditions to Check For Conditions That Should Exist
System
Feature
A Rock Pad ,~ Missing or Only one layer of rock exists ~ Replace rocks to design
moved rock above native soil in area 5 standard.
square feet or larger, or any
exposure of native soil.
A Rock-filled Missing or Trench is not full of rock. Add lazge rock (f30 Ib. each) so
trench for . moved rock that rock is visible above edge
discharge from ~ of trench.
pond
M Dispersion Pipe plugged Accumulated sediment that Pipe Cleaned/flushed.
trench with sediment exceeds 20% of the design
depth.
M Perforations Over 1/2 of perforations in Clean or replace perforated pipe.
plugged pipe are plugged with debris
and sediment.
M,S Not discharging Visual evidence of water Trench must be redesigned or
water properly discharging at concentrated rebuilt to standard. Elevation of
points along trench (normal lip of trench should be the same
condition is a"sheetflow" of (flat) at all points.
water along trench). Intent
~
is to prevent erosion
damage.
M,S Water flows out Maintenance person Facility must be rebuilt or
top of observes water flowing out redesigned to standards. Pipe is
"distributor" during any storm less than probably plugged or damaged
catch basin the design storm or its and needs replacement.
causing or appears likely to
cause damage.
M,S Receiving area Water in receiving area is Stabilize slope with grass or
over-saturated causing or has potential of other vegetation, or rock if
causing landslide. condition is severe.
If you are unsure whether a problem exists, please contact the Jurisdiction and ask for technical assistance.
Comments:
Key: A= Annual (March or April preferred) ,
M = Monthly (see schedule) -
S = After major storms
ATTACHMENT "A" (CONTINUED)
Maintenance Checklist for Ponds
Freq. Drainage ~ Problem Conditions to Check For Conditions T'hat Should Exist
System
Feature
M.S. General ~I Trash & debris Dumping of yard wastes Remove trash and debris and
buildup in pond such as grass clippings and dispose as prescribed by County
branches into basin. Waste Management Section
Unsightly accumulation of
non-degradable materials
such as glass, plastic, metal,
foam, and coated paper.
M.S. ,~ Trash rack Bar screen over outiet more Replace screen. Remove trash
plugged or than 25°/a covered by debris and debris and dispose as
missing or missing. prescribed by County Waste
Management Section.,
M ~ Poisonous Any poisonous vegetation Remove poisonous vegetation.
vegetation which may constitute a Do not spray chemicals on
hazard to the public. vegetation without obtaining
' Examples of poisonous guidance from the Cooperarive
vegetation include: tansy Extension Service and approval
ragwort, poison oak, from the County.
stinging nettles, devilsclub
M.S. ~I Fire hazazd or Presence of chemicals such Find sources of pollution and
pollution as natural gas, oil, and eliminate them. Water is free
gasoline, obnoxious color, from noticeable color, odor, or
odor, or sludge noted. contamination.
M ,~ Vegetation not For grassy ponds, grass For grassy ponds, selectively
growing or is cover is spazse and weedy thatch, aerate, and reseed ponds.
overgrown or is overgrown. For Grass cutting unnecessary unless
wetland ponds, plants aze dictated by aesthetics. For
sparse or invasive species wetland ponds, hand-plant
are present. nursery-grown wetland plants in
baze areas. Contact the
Cooperative Extension Service
for direcrion in invasive species
such as purple looseime and reed
canary grass. Pond bottoms
should have uniform dense
. coverage of desired plant species.
M ~ ,~ Rodent holes Any evidence of rodent Rodents destroyed and dam or
holes if facility is acting as berm repaired. Contact the
a dam or berm, or any Thurston County Health Dept.
evidence of water piping for guidance.
through dam or berm via
rodent holes.
M Insects When insects such as wasps Insects destroyed or removed
and hornets interfere with from site. Contact Cooperative
maintenance activities, or Extension Service for guidance.
when mosquitoes become a
nuisance.
A ,~ Tree Growth Tree growth does not allow Trees do not hinder maintenance
maintenance access or activities. Selectively cultivate
interferes with maintenance trees such as alders for firewood.
activity (i.e., slope mowing,
silt removal, or e ui ment .- --. -- - - - - -
Freq. Drainage ~ Prolilem Conditions to Check Far
~ Conditions That Should Exist
System
Feature
movements). If trees aze
not interfering with access,
leave trees alone.
M Side slopes of ~ Erosion on Check around inlets and Find causes of erosion and
pond berms or at outlets for signs of erosion. eliminate them. Then slopes
entrance/ Check berms for signs of should be stabilized by using
exit sliding or settling. Action appropriate erosion control
is needed where eroded measure(s); e.g., rock
damage over 2 inches deep reinforcement, planting of grass,
and where there is potential compaction.
for continued erosion.
M Storage area ~ Sediment Accumulated sediment that Sediment cleaned out to designed
buildup in pond exceeds 10% of the pond shape and depth; pond
designed pond depth. reseeded if necessary to control
Buried or partially buried erosion:
~' outlet structure probably
indicates significant
sediment deposits.
A Pond dikes ~I Settlements Any part of dike which has Dike should be built back to the
settled 4 inches lower than design elevation.
the design elevation.
A Emer-gency ~ Rock missing Only one layer of rock Replace rocks to design
overflow/ exists above narive soil in standazds.
spillway area 5 square feet or larger,
or any exposure of native
soil.
One time Emer-gency ~ Overflow Side of pond has no area Contact County for guidance.
overflow/ missing with large rocks to handle
spillway emergency overflows.
If you are unsure whether a problem exists, please contact the Jurisdiction and ask for technical assistance.
Comments:
Key: A= Annual (Mazch or April preferred)
M = Monthly (see schedule)
S = After major storms
SECTION 2 - RESPONSIBLE ORGANIZATION
The owners or owner's representative shall be responsible for the operation and
maintenance of all on-site drainage facilities.
SECTION 3- VEGETATION MANAGEMENT PLAN
All disturbed pervious areas within the site will be landscaped to provide an '
aesthetically pleasing environment.
SECTION 4 - SOURCE CONTROL
Warning signs (e.g., "Dump No Waste - Drains to Groundwater") will be embossed
or painted on or adjacent to all storm drain inlets and will be repainted
periodically as necessary.
Appendix I
Prelzmina~~y Drainage Calculations
DRAINAGE CALCULATION5
The following calculations were based on the requirements ~contained in the WSDOE 1992
Stormwater Management Manual.
DESIGN AND BASIN INFORMATION SUMMARY:
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~ ~~~ ~ ~ ~+ ~ ~, Past~ Development
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Basrn ~Area Summary (Acres} .~ ' ~ ~~
.~~a ~,,.~.~. '~-
A B Total
Impervious Roadway 0.50 0.13 0.63
Concrete Sidewalk 0.09 0.02 0.11
Impervious Driveway 025 0.05 0.30
Impervious Roof Area 0.82 0.16 0.98
Disturbed Pervious 2.46 0.47 2.93
Total 4.12 0.83 4.95
Roof Area: 2,000 sf/lot
Driveway Area: 600 sf/lot
Soil Classification:
SCS Soil Classification: Spanaway Gravelly Sandy Loam
Hydrologic Group: A '
Design Infiltration Rate: 20"/hr
BASIN `A' WATER QUALITY CALCULATIONS
Minimum Stormwater Treatment Area Required:
StormShed software was used to model the runoff from a portion of the on-site
roadway, sidewalks, and driveway areas. The 6-month storm event resulted in a
peak volume of 3,217 cf.
The DOE manual, section III-4.32, requires that "the permanent pool volume
equals the runoff volume from the 6=month, 24-hour design storm. Therefore,
using 360 LF of 4-foot diameter pipe as a wet vault, with a cross-sectional area of
10 sf at a 3-foot depth, results in an available pool volume of 3,600 cf; which
exceeds the required volume of 3,217 cf.
See the following StormShed modeling output.
BASIN `B' WATER QUALITY CALCULATIONS
Minimum Stormwater Treatment Area Required:
Formula 6-9 from page III-6-14: b= Qn - Zy
1.486 yl.ss~ So.S
Qsmo = 0.05 cfs (see attached StormShed output)
n = 0.07
Z=3
y=2"=0.1667'
s = 0.02
b = 0.83'
0.83' x 200' long swale = 166 sf
Stormwater Treatment Area Provided:
166 sf / 2' wide = min. 83' long
Total Treatment Area Prouided 2' wide x 380' long = 760 sf > 166 sf .: OK
Chech Velocity:
V=Q/A = 0.05 cfs /((2)(0.1667) +(3)(0.1667)2) = 0.1 cfs < 1.5 cfs .: OK ~
BASINS `A' AND `B' WATER QUANTITY CALCULATIONS
*See attached StormShed software output
3- 70' long x 6' wide x 4.5' deep infiltration galleries with 3' dia. perf. Pipe
Void ratio = 0.30
3 galleries x [[(70')(6')(4.5'~ (70')(3.14)(3'^2)/4] (0.3) + (70')(3.14)(3'^2)/4]
Total Storage Volume Prouided = 2, 740 cf
Active Live Volume = 2,379 at Elev. = 325.85' per StormShed modeling
2,379 cf < 2,740 cf .: OK
48 Hour Drawdown:
((3)(70' x 6')(20 in/hr)(1'/12")(48 hours) = 100,800 cf > 2,379 cf .: OK
~
Olympic Engineering Mountain Meadows , StormShed
#05002 4/17/2005
Basins `A' Water Qualitv
Basin A Event Summary:
BasinlD Peak Q Peak T Peak Vol Area Method Raintype
Event
------- (cfs) , (hrs) (ac-ft) ac /Loss
Basin A 0.24
i 8.00 0.0782 0.89 SCS/SCS TYPE1A 6 mo
Drainage Area: Basin A
Hyd Method: SCS Unit Hyd Loss Method: SC S CN Number
Peak Factor: 484.00 SCS Abs: 0.2 0
Storm Dur 24.00 hrs
Area CN TC
Pervious 0.0000 ac ' 78.00 0.02 hrs
Impervious 0.8900 ac 98.00 0.03 hrs
Total 0.8900 ac
Supporting Data:
Impervious CN Data: ,
road 98.00 0.5800 ac °
s/w 98.00 0.2300 ac
d/w 98.00 0.0800 ac
Pervious TC Data:
Flow type: Description: Length: Slope: Coeff: Travel Time
Fixed None Entered 0.00 ft 0.00% 1.0000 0.00 min
Impervious TC Data:
Flow type: Description: Length: Slope: Coeff: Travel Time
Fixed None Entered 0.00 ft 0.00% 0.0000 0.00 min
Basins `A' and `B' Water Quanitit
RLPCOMPUTE (Infiltration Level Pool] SUMMARY
100 yr MatchQ=PeakQ= 1.5213 cfs Peak Out Q: 0.8975 cfs - Peak Stg: 325.85 ft-
Active Vol: 2379.95 cf
Summary Report of all RLPooI Data
Project Precips
[2 yr] 2.00 in
[5 yr] 2.50 in
[10 yr] 3.00 in
[25 yr] 3.00 in .
[100 yr] 4.00 in
[6 mo] 1.28 in
BASLIST2
[Basin.A/B Combined] Using [TYPE1A~ As [100.yr]
LSTEND
BasinlD Peak Q Peak T Peak Vol Area Method Raintype
Event
------- (cfs) (hrs) (ac-ft) ac /Loss
Basin A/B Combined 1.5213 8.00 0.7647 3.97 SCS/SCS
~
__ _ ._ - . .. __ _ TYPE1A _ 100 yr -. ~ .. _ . . _ __ ._ _
l
1 of 2
Olympic Engineering
Mountain Meadows
#05002
BASLIST [TYPE1A] AS [100 yr] DETAILED
~ [Basin A/B Combined]
LSTEND
Drainage Area: Basin A/B Combined
Hyd Method: SCS Unit Hyd Loss Method: SCS CN Number
Peak Factor: 484.00 SCS Abs: 0.20
Storm Dur 24.00 hrs
Area CN TC
Pervious 2.9300 ac 77.00 0.61 hrs
Impervious 1.0400 ac 98.00 0.03 hrs
Total 3.9700 ac
Supporting Data:
Pervious CN Data:
Landscaping 77.00 2.9300 ac
Impervious CN Data:
Roadway 98.00 0:6300 ac
Driveways 98.00 0.3000 ac
Sidewalks 98.00 0.1100 ac
Pervious TC Data: ~
Flow type: Description: ~ Length: Slope: Coeff:
Sheet Landscaping 445.00 ft 2.60% 0.1500
Impervious TC Data:
Flow type: Description: Length: Slope: Coeff:
Shallow Impervious 408.00 ft 2.10% 27.0000
HYDLIST SUMMARY
[100 yr out]
LSTEND
HydID Peak Q Peak T Peak Vol Cont Area
------- (cfs) (hrs) (ac-ft) (ac)
100 yr out 0.90 9:00 0.7656 3.9700
STORLIST
[Infiltration Gallery]
LSTEND
Node ID: Infiltration Gallery
Desc: Infiltration Gallery
Start EI: 322.0000 ft Max EI: 326.5000 ft
Contrib Basin: Contrib Hyd:
Length Width Void Ratio
70.0000 ft 18.0000 ft 49.00
DISCHLIST
[Infiltration Gallery]
LSTEND
StormShed
4/17/2005
Travel Time
36.84 min
Travel Time
1.74 min
Control Structure ID: Infiltration Gallery - Infiltration control structure
Descrip: Infiltration Gallery
Start EI Max EI Increment ~•
322.0000 ft 327.5000 ft 0.10
Infil: 20.00 in/hr Multiplier: 1.00
2 of 2
Appendix II
__ _ _ _. - . _ _. Soils Report
SOIL EVALUATION REPORT
FORM 1: GENERAL SITE INFORMATION
PROJECT TITLE: Antush Plat SHEET: 1 OF 1
PROJECT N0.:05105 DATE: 3/22/05
PREPARED BY: William Pamell, P.E.
1. SITE ADDRESS: 8818 Bumett Road SE, Yelm 98597
TPN:21713310400,21713310401,21713310402
2. PROJECT DESCRIPTION: Create a residential plat.
3. SITE DESCRIPTION: The 4.89 acre rectangular shaped project site is currently occupied by a
single residential dwelling and several outbuildings. Site relief is gently sloping with a 2-3% east to west
slope, varying from an elevation of 342 ft. at the northeast property comer to an elevation of 328 ft.
along the west property line. Site vegetation consists of low cut pasture grasses. The project site is
bounded by Burnett Road to the west and residential property to the north, east and south. On-site soils
are a well-drained Spanaway series formed in gravelly glacial outwash.
4. SUMMARY OF SOILS WORK PERFORMED: Two test pits were excavated by backhoe to a
maximum depth of 144" below existing grade. Soils were inspected by entering and visually logging
each test pit to a depth of four feet. Soils beyond four feet were inspected by examining backhoe
tailings. One double ring infiltration test was oompleted. Test pit soil log data sheets and infiltration test
results are included in this report.
5. ADDITIONAL SOILS WORK RECOMMENDED: Additional soils work should not be necessary
unless drainage infiltration facilities are located outside the general area encompassed by the soil test
pits.
6. FINDINGS: The Natural Resource Conservation Senrice soil survey for Thurstan County mapped
the on-site soils as a Spanaway Gravelly Sandy Loam (110). All test pits confirmed the Spanaway
designation generally profiling a gravelly very fine sandy loam surface soil overlying a very to extremely
gravelly & cobbley coarse-medium sand substratum. The substratum gravels and sands were slightly
loose to slightly tight. Winter water. table was not present and no indicators were visible. A double ring
infiltration test revealed an infiltration rate of 80 in/hr at 72" below the existing grade in test pit #1.
7. RECOMMENDATIONS: The Spanaway soil series is a somewhat excessively drained soil that
formed in gravelly glacial outwash. Infiltration rates are generally rapid in the substratum soils. The
specified substratum C horizon soils should be targeted for all drainage infiltration facilities as noted in
the attached soil log data sheets. A design infiltration rate of 20 in/hr or less would be appropriate for
these targeted soils.
During construction, care must be taken to prevent the erosion of exposed soils: Drainage facility
infiltration surfaces must be properly protected from contamination by the fine-grained upper horizon
soils and from compaction by construcfion site activities. Soils not properly protected will cause
drainage infittration facilities to.prematurely fail.
I hereby certify that I prepared this report, and conducted or supervised the performance of related
work. I certify that I am qualified to do this work. I represent my work to be complete an accurate within
the bounds of uncertainty inherent to the practice of soils science, and to be suitable for its intended
use. _ ._~ ~ ~,..
SIGNED: ~,1.~,~ ' c~~ ,~ ~fti~` ° y~,. 'p~,,,~
~ ~~
DATE: 3I ZZ ~j,S ' ~ ~ .,,. ~:: .d+,
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SOIL EVALUATION REPORT
FORM 2: SOIL LOG INFORMATION
PROJECT TITLE: Antush Plat SHEET: 1 OF 2
PROJECT N0.:05105 DATE: 3/18/05
PREPARED BY: William Parnell, P.E. ~
SOIL LOG: #1
LOCATION: 60 ft. east and 20 ft. north of the southwest property comer.
1. TYPES OF TEST DONE: 2. SCS SOILS SERIES: 3. LAND FORM:
Double Ring Infiltration Spanaway (110) Terrace
4. DEPOSITION HISTORY:
~ 5. HYDROLOGIC SOIL 6. DEPTH OF SEASONAL HW:
GROUP:
Glacial Outwash B Unknown
7. CURRENT WATER 8. DEPTH TO IMPERVIOUS 9. MISCELLANEOUS:
DEPTH: LAYER:
Greater than bottom of hole Greater than bottom of hole Level
10. POTENTIAL FOR: EROSION RUNOFF PONDING
Minimal Slow Minimal
11. SOIL STRATA DESCRIPTION: See Following chart
12. SITE PERCOLATION RATE: See FSP
13. FINDINGS & RECOMMENDATIONS: A double ring infiltration test completed at 72" below the
exisfing grade revealed an infiftration rate of 80 in/hr. Use a design infiltration rate of 20 in/hr or less for
drainage infiltration facilities located in the C2, C3 and C4 horizon soils.
Soils Strata Description
Soil Log #1
Horz Death Color Texture %CL %ORG CF STR MOT IND CEM ROO <X> FSP
A1 0"- 24" 10YR2/2 GrVFSaLm <15 <5 <10 1 SBK - - - ff 2-6 2
Bw 24"- 30" 10YR3/3 GrVFSaLm <15 - <25 1 SBK - - - ff 2-6 4
C1 30"- 36" 10YR3/6 VGr&Cob <10 - <40 SG - - - 6-20 20
LmMSa
C2 36"- 72" 10YR4/6 ExGr&Cob <1 - <75 SG - - - - >20 20
MSa
C3 72"- 96" 10YR5/2 ExGr&Cob <1 - <75 SG - - - - >20 20
M-FSa
some stones
C4 96"- 144" 10YR5/2 ExGr&Cob <1 - <80 SG - - - - >20 20
C-MSa
some stones
SOIL EVALUATION REPORT
FORM 2: SOIL LOG INFORMATION
PROJECT TITLE: Antush Plat SHEET: 2 OF 2
PROJECT N0.:05105 DATE: 3/18/05
PREPARED BY: William Pamell, P.E.
SOIL LOG: #2
LOCATION: 160 ft. east and 20 ft. north of the southwest property comer.
1. TYPES OF TEST DONE: 2. SCS SOILS SERIES: 3. LAND FORM:
~ Double Ring Infiltration Spanaway (110)
~ Terrace
4. DEPOSITION HISTORY: 5. HYDROLOGIC SOIL 6. DEPTH OF SEASONAL HW:
GROUP:
Glacial Outwash B Unknown
7. CURRENT WATER 8. DEPTH TO IMPERVIOUS 9. MISCELLANEOUS:
DEPTH: . LAYER:
Greater than bottom of hole Greater than bottom of hole Level
10. POTENTIAL FOR: EROSION RUNOFF PONDING
Minimal Slow Minimal
11. SOIL STRATA DESCRIPTION: See Following chart
12. SITE PERCOLATION RATE: See FSP
13. FINDINGS & RECOMMENDATIONS: Use a design infiltration rate of 20 in/hr or less for drainage
infiltration facilities located in the C2 and C3 horizon soils.
Soils Strata Description
Soil Log #2
Horz Depth Color Texture %CL %ORG CF STR MOT IND CEM ROO <X> FSP
A1 0"- 20" 10YR2/2 Gr&Cob <15 <5 <10 1 SBK - - - ff 2-6 2
VFSaLm
some stones
Bw 20"- 26" 10YR3/3 GrVFSaLm <15 - <25 1SBK - - ~ - ff 2-6 4
C1 26"- 31" ~ 10YR3/6 VGr&Cob <10 - <40 SG - - - - 6-20 20
LmMSa
C2 31"- 72" 10YRM6 ExGr&Cob <1 - <65 SG - - - - >20 20
C-MSa
some stones
C3. 72"-144" 2.5Y5/2 VGrMSa <1 - <4p SG - - - - >20 20
Abbreviations
Textural Class
(Texture) Structure
(STR) Grades of Structure
Cobble -Cob Granular - Gr Stron - 3
Stone - St Blocky - Blk Moderate - 2
Gravelly - Gr Platy - PI Weak - 1
Sand - Sa Massive . - Mas
Loamy - Lm Single Grained - SG
Silt - Si Sub-An ular Block - SBK
Cla ey - CI
Coarse - C
Ve - V
Extremel - Ex
Fine - F
Medium - M
Induration 8~ Cementation
(IND) (CEM)
Weak - Wk
Moderate - Mod
Strong - Str
Mottles MOT
1 Letter Abundance 1st Number Size 2nd Letter Contrast
Few - F Fine - 1 Faint - F
Common - C Medium - 2 Distinct - D
Many - M Coarse - 3 Prominent - P
Roots (ROO)
1 st Letter Abundance 2nd Letter Size
Few - f Fine - f
Common = c Medium - m
Many - m Coarse - c
<X> - Generalized range of infiltration rates trom 5G5 soil survey (<x>)
FSP - Estimated Field Saturated Percolation rate based on horizon specific
factors.
DOUBLE RING INFILTRATION TEST
Antush Plat
Test Date 3/23/2005
Completed By : William Parnell, P.E.
PE Job : #05105
DOUBLE RING INFILTRATION TEST
Test Hole # 1( test run @ 72" be low existing ground surface )
Start Sto Ela sed Time Total Dro Infiltration Rate
( Min ) ( Min ) ( Min ) ( Inches ) ( In/Hr )
0 3' 30" 3' 30" 6
3' 30" 7' 15" 3' 45" 6
7' 15" 11' 30" 4' 15" 6
11' 30" 15' 45" 4' 15" 6
15' 45" 20' 15" 4' 30" 6
20' 15" 24' 45" 4' 30" 6
24' 45" 29' 30" 4' 45" 6
29' 30" 34' 00" 4' 30" 6
34' 00" 38' 30" 4' 30" 6
38' 30" 43' 00" 4' 30" 6
43' 00" 47' 30" 4' 30" 6
47' 30" 52' 00" 4' 30" 6
52' 00" 56' 30" 4' 30" 6
56' 30" 1: 00' 30" 4' 30" 6 80
Appendix III
__ __ _ _ - --
_. _ _ - -Vicinity Map
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14ppendix IV
Drainage Basin Map
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