Prelim Drainage ReportBurnett Estates
Ye 1 m, WA
Preliminary Drainage Report
December 2004
PRELIMINARY DRAINAGE REPORT
Yelm, Washington
December 2004
Project Information
Project: Burnett Estates
Prepared for: Rainier General Development
Contact: Doug Bloom
P.O. Box 627
Rainier, WA 98576
(360) 446-3083
Reviewing Agency
Jurisdiction: City of Yelm
Project Number:
Project Contact Jim Gibson
(360) 458-8438
Project Engineer
Prepared by: Olympic Engineering Services
1252 Devon Loop NE
Olympia, WA 98506
(360) 870-2561 FAX (360) 705-9361
Contact: Chris M. Merritt, P.E.
OES Project No.: 04007
File Name: C:\File Cabinet\Business\Olympic\Projects\2004\04007 -
Burnett Road Plat\Drainage\04007_pdr.doc
PROJECT ENGINEERS CERTIFICATION: I hereby certify that this
Preliminary Drainage Report for the Burnett Estates Plat in the City of
Yelm, Washington has been prepared by me or under my supervision and
meets the intent of the Thurston County Drainage Design and Erosion
Control Manual (DDECM), 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.
1
Table of Contents
APPENDICES
PART I STORM DRAINAGE REPORT ............................................... .........2 Appendix 1- Preliminary Drainage
Calculations
SECTION 1 -PROPOSED PROJECT DESCRIPTION ...................... .........2
Appendix 2- Vicinity Map
SECTION 2 -EXISTING CONDITIONS ............................................. .........3 Appendix 3- Drainage Basin Map
SECTION 3 -INFILTRATION RATES /SOILS REPORT ................. .........3
SECTION 4 -WELLS AND SEPTIC SYSTEMS ................................. .........4
SECTION 5 -FUEL TANKS ................................................................ .........4
SECTION 6 - SUB-BASIN DESCRIPTION ........................................ .........4
SECTION 7 -ANALYSIS OF 100-YEAR FLOOD ............................... .........4
SECTION 8 -AESTHETIC CONSIDERATIONS FOR FACILITIES .........4
SECTION 9 -DOWNSTREAM ANALYSIS ......................................... .........4
SECTION 10 -COVENANTS, DEDICATIONS, EASEMENTS ........... .........5
SECTION 11 -ARTICLES OF INCORPORATION .............................. .........5
PART II EROSION CONTROL REPORT ....................................................6
SECTION 1 -CONSTRUCTION SEQUENCE AND PROCEDURE...........6
SECTION 2 -TRAPPING SEDIMENT ........................................................6
SECTION 3 -PERMANENT EROSION CONTROL ...................................7
SECTION 4 - GEOTECHNICAL 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 ORGANIZATION ......................................18
SECTION 3 -VEGETATION MANAGEMENT PLAN ..............................18
SECTION 4 - SOURCE CONTROL ............................................................18
11
PART I STORM DRAINAGE REPORT
SECTION 1 -PROPOSED PROJECT DESCRIPTION
Prepared for: Rainier General Development
Contact: Doug Bloom
P.O. Box 627
Rainier, WA 98576
(360) 446-3083
Parcel Number:
Total Site Area:
Zoned:
Site Address:
Required Permits:
Section, Township, Range:
21713310000
4.81 Acres
R-6
8910 Burnett Road SW
Yelm, WA 98597
Grading, Utility, Building, etc.
Section 13
Township 17 North
Range 1 East, W.M.
Project Overview
The project site is located adjacent to Burnett Road in Yelm. The applicant
proposes to construct a new public roadway through the parcel connecting Burnett
Road to a road currently under construction on the east side of this project and to
install utility services to serve 18 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 wetpond 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 wetpond will provide treatment for stormwater runoff from Basin `A'
(on-site roadway) and a proposed biofiltration swale will provide treatment for
Basin `B' (Burnett Road frontage improvements). The proposed biofiltration swale
and wetpond exceeds the minimum required surface area per the Thurston County
DDECM. 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 Thurston
County DDECM. See Preliminary Drainage Calculations in Appendix.
Roof Runoff:
Roof runoff from each residential home will be tightlined to individual lot
infiltration drainrock drywells. The drywells shall be sized per Table 8.2 in the
DDECM using a soil hydrologic Group "A" classification.
SECTION 2 -EXISTING CONDITIONS
The project site contains a single family residence with several outbuildings. The
home will remain and some of the outbuildings will be demolished. Site
topography is moderately sloping down from the NE to SW corner of the site. Site
vegetation mainly consists of a grass pasture. The project site is bounded by
single-family residential property to the south, west, and north, and a single
family development currently under construction to the east, asingle-family
development currently under construction to the east.
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
appear to be no drains, channels, or swales located within the project site, or
immediately adjacent to the proposed development.
The project site is not 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 Conservation Service (SCS) soil survey of Thurston County classifies the
on-site soils as Spanaway Gravelly and Stony Sandy Loam (Hydrologic Group A).
Soils testing will be conducted as needed for storm drainage design during the
final design phase of this project and the design will be revised if needed.
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 north and
northeast, 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 CONSIDERATIONS 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. Mulch, 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 & 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 Swales
c. Wetpond
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 -REQUIRED 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.
ATTACHMENT `A'
Inspection Period:
MAINTENANCE PROGRAM
COVER SHEET
Number of Sheets Attached:
Date Inspected:
Inspector's Signature:
ATTACHMENT "A": MAINTENANCE PROGRAM
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 repaired or replaced.
(rusted, bent damaged, rust is 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 area of pipe
by more then 20%).
M ~ Pipe has major cracks or Pipe repaired or replaced.
tears allowing groundwater
leakage.
M.S. Swales ~ 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. Remove
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 possible. 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 Problem Conditions To Check For Conditions That Should Exist
System Feature
M,S General J 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 J Sediment or debris (in the No sediment or debris in the
basin) that exceeds 1/3 the catch basin. Catch basin is
depth from the bottom of basin dug out and clean.
to invert of the lowest pipe into
or out of the basin.
M,S J Trash or debris in any inlet or Inlet and outlet pipes free of
pipe blocking more than U3 of trash or debris.
its height.
M J 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).
and/or top
slab
M J Top slab has holes larger than 2 Top slab is free of holes and
square inches or cracks wider cracks.
than U4 inch (intent is to make
sure all material is running
into the basin).
M J 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 frame from
the top slab.
A J Cracks in Cracks wider than U2 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 J Cracks wider than U2 inch and No cracks more than U4 inch
longer than 1 foot at the joint of wide at the joint of inlet outlet
any inlet outlet pipe or any pipe.
evidence of soil particles
entering catch basin through
cracks.
A J Settlement Basin has settled more than 1 Basin replaced or repaired to
/misalign- inch or has rotated more than 2 design standards. Contact a
went inches out of alignment. professional engineer for
evaluation.
Frequency Drainage
System Feature J R,eq'd Problem Conditions To Check For Conditions That Should Exist
M,S J Fire hazard 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 inlet/outlet 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 =After major storms
ATTACHMENT "A" (CONTINUED)
Maintenance Checklist for Grounds (Landscaping)
Frequency Drainage ~ Problem Conditions to Check For Conditions That Should Exist
System
Feature
M General ~ Weeds Weeds growing in more than Weeds present in less than 5% 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 azeas are filled,
contoured, and seeded.
A Trees 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 ~ Trees or shrubs that have Replant tree, inspecting for
been blown down or knocked injury to stem or roots. Replace
over. if severely damaged.
A ~ Trees or shrubs which aze Place stakes and rubber-coated
not adequately supported or ties around young trees/shrubs
are leaning over, causing for support.
exposure of the roots.
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 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 large rock (±30 lb. 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 ou[ 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 That Should Exist
System
Feature
M.S. General ~ 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 outlet more Replace screen. Remove trash
plugged or than 25% 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 Cooperative
vegetation include: tansy Extension Service and approval
ragwort, poison oak, from the County.
stinging nettles, devilsclub
M.S. ,~ Fire hazard 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 sparse and weedy thatch, aerate, and reseed ponds.
overgrown or is overgrown. For Grass cutting unnecessary unless
wetland ponds, plants are dictated by aesthetics. For
sparse or invasive species wetland ponds, hand-plan[
are present. nursery-grown wetland plants in
bare areas. Contact the
Cooperative Extension Service
for direction in invasive species
such as purple looseime and reed
canary grass. Pond bottoms
should have uniform dense
coverage of desired plan[ 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, ore ui ment
Freq. Drainage ~ Problem Conditions to Check For Conditions That Should Exist
System
Feature
movements). If trees are
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°Io 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 ~ 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 native soil in standards.
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 (March 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
Preliminary Drainage Calculations
DRAINAGE CALCULATIONS
The following calculations were based on the requirements contained in the Drainage
Design and Erosion Control Manual (DDECM) for Thurston County, 1994 Edition.
DESIGN AND BASIN INFORMATION SUNIlVIARY:
Yost De'v~lopxnent Basin Area Summary (Acres)
A B C Total
Impervious Roadway 0.58 0.06 0.04 0.68
Concrete Sidewalk 0.08 0.02 0.01 0.11
Impervious Driveway 0.23 0 0 0.23
Impervious Roof Area 0.51 0 0.28 0,7g
Disturbed Pervious 2.13 0.02 1.05 3.20
Total 3.53 0.10 1.38 5.01
Roof Area: 2,000 sf/lot
Driveway Area: 600 sf/lot
Soil Classification:
SCS Soil Classification: Spanaway
Hydrologic Group: A
Design Infiltration Rate: 20" /hr
BASIN `A' WATER QUALITY CALCULATIONS
Minimum Stormwater Treatment Area Required:
Using aroadway/driveway/sidewalk impervious surface area of 0.89 ac and
DDECM design value of 2.5% per impervious acre results in a required wetpond
bottom area of
0.025 x (0.58 ac + 0.08 ac + 0.23 ac) x 43,560 sf/ac = 969 sf
Stormwater Treatment Area Provided:
Total Treatment Area Provided = 990 sf > 969 sf .: OS
BASIN B' WATER QUALITY CALCULATIONS
Minimum Stormwater Treatment Area Required:
Using aroadway/sidewalk impervious surface area of 0.08 ac and DDECM
design value of 2,000 sf/impervious acre results in a required biofiltration surface
area of
2,000 sf x (0.06 ac + 0.02 ac) = 160 sf
Stormwater Treatment Area Provided:
2' wide x 210' long biofiltration swale = 410 sf
Total Treatment Area Provided = 4I0 sf > 160 sf .: OK
BASINS `A' AND `B' WATER QUANTITY CALCULATIONS
*See attached StormShed software output
Stage Elevation Live Storage Volume
Pond Bottom
Peak Stage*
2 ft Freeboard
325.5 0 cf
326.0 1,028 cf
327.0 3,706 cf
328.0 7,262 cf
Total Storage Volume Provided
48 Hour Drawdown:
= 7,262 c f
(1,856 sf)(20 in/hr)(1'/12")(48 hours) =148,480 cf
BASIN `C'
Basin `C' is non-tributary to the on-site infiltration facility. Stormwater runoff from
this portion of the Burnett Road frontage will flow southerly along the gutter line to
an existing catch basin near the Prairie Vista Loop intersection.
Olympic Engineering Services
StormShed
12/27/2004
RLPCOMPUTE [Infiltration Level Pool] SUMMARY
100 yr MatchQ=PeakQ= 1.3047 cfs Peak Out Q: 1.1294 cfs -Peak Stg: 326.00 ft -
Active Vol: 1027.73 cf
Summary Report of all RLPooI Data
Project Precips
[2 yr] 2.00 in
[10 yr] 3.00 in
[100 yr] 4.00 in
[6 mo] 1.28 in
BASLIST2
[Basin A/B Com
LSTEND
BasinlD Peak Q
Event
---- (cfs)
Basin A!B Combined
TYPE1A
biped] Using [TYPE1A] As [100 yr]
Peak T Peak Vol Area Method Raintype
(hrs) (ac-ft) ac /Loss
1.3047 8.00 0.6258 3.12 SCS/SCS
100 yr
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 2.1500 ac 77.00 0.61 hrs
Impervious 0.9700 ac 98.00 0.03 hrs
Total 3.1200 ac
Supporting Data:
Pervious CN Data:
Landscaping 77.00 2.1500 ac
Impervious CN Data:
Roadway 98.00 0.6400 ac
Driveways 98.00 0.2300 ac
Sidewalks 98.00 0.1000 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 PeakQ Peak T Peak Vol Cont Area
------ (cfs) (hrs) (ac-ft) (ac)
100 yr out 1.13 8.25 0.6256 3.1200
Travel Time
36.84 min
Travel Time
1.74 min
1 of 2
Olympic Engineering Services
STORLIST
[Infiltration Pond]
LSTEND
Node ID: Infiltration Pond
Desc: Infiltration Pond
Start EI: 325.5000 ft
Contrib Basin:
Stage Input Volume
325.50 0.00 cf 0.00 cf
326.00 1028.00 cf 1028.00 cf
327.00 3706.00 cf 3706.00 cf
328.00 7262.00 cf 7262.00 cf
DISCHLIST
[Infiltration Pond]
LSTEND
Max EI: 328.0000 ft
Contrib Hyd:
Volume
0.0000 acft
0.0236 acft
0.0851 acft
0.1667 acft
Control Structure ID: Infiltration Pond -Stage Discharge rating curve
Descrip: Infiltration Pond
Start EI Max EI Increment
325.5000 ft 328.0000 ft 0.10
Stage Discharge
325.5000 ft 0.0000 cfs
326.0000 ft 1.1300 cfs
327.0000 ft 1.5500 cfs
328.0000 ft 2.0000 cfs
StormShed
12/27/2004
2 of 2
04007.cv1
volume of a Contour Map
using Survey/Civil Solutions for AutoCA6 by Boston Harbor Software Inc
-----------------------
gate Pcepa.red: 12./27/2004
-----------------------
~rawi.ng. Name:z.civil.dwg
volume 325.50 to 326.00 = 1,028 ft3
volume 326.00 to 32"7.00 = 2,678 ft3
volume 32.7..00 ~0 32.8.00 = 3,556 ft3
-----------------
Total --------------
volume = ------------
7,262 ------------
ft3
269 yd3
0,.17 Acre Ft.
Page 1
Appendix III
Vicinity Map
vi
z
0
0
W
~ r
L1.
~ ~
w Q ~
~ ~ z Q
~ O ~ ~
z ~ z U
m ~ ~ >
o a
0
H
a
J
a a
a ~
~ ~
~ ~
~_ ~
Z W
V ~
~ Z
m
Appendix IV
Drainage Basin Map
Q
0
N
W
W
LL
O
O
11 ~
_ ~
J Q
Q ~
U
O
W
~ N
Y.
w
~ ~
w Q d
m ~ z Q
~ O ~ ~
z ~ z Z
m D ~
o a m
~ ~
0
a
a a
J
a
Z to
y W
Q 4
m H
W w
a ~
Z W
a ~
a~ ~
o m
W
xz
.~ ao
~~ o~
~~ ~~
N 01 C Q
O lA j 3
1~ O N ~
~ n ~ d
N
t~D~ ~_~
v v .N-. O
(, J z ~
1: !L o~ u
'i: ~ w u
zZ
'' J c7 °m
0~w