Storm Drainage and Erosiion ControlStormwater Drainage Report
Short Plat of Timber Estates
Yelm, WA
June 2004
~~~~~'
o~
Project Information
Project:
Prepared for:
Contact:
Short Plat of Timber Estates
Airborne Properties
Brian Reynolds
7882 Old Hwy 99 SE
Olympia, WA 98501
(360) 754-7200
Reviewing Agency
Jurisdiction:
Project Number:
Project Contact
Project Engineer
Prepared by:
Contact:
Job #:
File Number:
City of Yelm
2M Enterprises LLC
15345 Sunwood Blvd Suite 302
Tukwila, WA 98188
Karl Lundberg, PE
Table of Contents
PART I STORM DRAINAGE REPORT
SECTION 1 -PROPOSED PROJECT DESCRIPTION .............................. 2
SECTION 2 -EXISTING CONDITIONS ................................................... 4
SECTION 3 -INFILTRATION RATES/SOILS REPORT .......................... 4
SECTION 4 -WELLS AND SEPTIC SYSTEMS ....................................... 5
SECTION 5 -FUEL TANKS ...................................................................... 5
SECTION 6 -SUB-BASIN DESCRIPTION ............................................... 5
SECTION 7 -ANALYSIS OF 100 YEAR FLOOD ..................................... 5
SECTION 8 -AESTHETIC CONSIDERATIONS ..................................... 5
SECTION 9 -DOWNSTREAM ANALYSIS AND FACILITY SIZING ..... 5
SECTION 10 -COVENANTS, DEDICATIONS, EASEMENTS ................ 6
SECTION 11 -ARTICLES OF INCORPORATION ................................... 6
PART II EROSION CONTROL REPORT
SECTION 1 -CONSTRUCTION SEQUENCE AND PROCEDURE .......... 6
SECTION 2 -TRAPPING SEDIMENT ...................................................... 7
SECTION 3 -EROSION CONTROL & SITE RESTORATION ................. 8
SECTION 4 -GEOTECHNICAL ANALYSIS AND REPORT ................... 8
SECTION 5 -INSPECTION SEQUENCE .................................................. 8
SECTION 6-CONTROL OF POLLUTANTS ............................................. 8
PART III MAINTENANCE PLAN
SECTION 1 -REQUIRED MAINTENANCE ............................................. 9
SECTION 2 -RESPONSIBLE ORGANIZATION .................................... 19
SECTION 3 -VEGETATION MANAGEMENT PLAN ........................... 19
SECTION 4 -SOURCE CONTROL ......................................................... 19
APPENDICES
Appendix I- Vicinity Map
Appendix II -Drainage Plan
Appendix III -Residential Maintenance Agreement
Appendix I V -Soils Report
Short Plat of Timber Estates, Drainage Report
PART I STORM DRAINAGE REPORT
The format of this report follows the outline provided in the 1992 Department of Ecology Drainage
Design and Erosion Control Manual.
SECTION 1-PROPOSED PROJECT DESCRIPTION
Project Proponent:
Parcel Numbers:
Total Site Area:
Zoned:
Site Address:
Required Permits:
Section, Township, Range
Airborne Properties
7882 Old Hwy 99
Olympia, WA. 98501
22730140700
2.45 acres
R-4
10826 SE Vancil Road Yelm, WA 98597
Grading, Utility
Section 13, Township 17N, Range 1 East, W.M.
Thurston County, Washington
The site is located in the City of Yelm and is bordered on the north side by a subdivision, on the south by
an undeveloped parcel and to the west by Vancil Road.
The proposal is to convert this site to 9single-family home sites with one of the lots zoned for a duplex. .
There are no structures located on this property. These lots will access from a public road extending from
Vancil Road approx. 500 feet to a permanent cul-de-sac. These lots will be served by the City of Yelm
water and sewer system.
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Short Plat of Timber Estates, Drainage Report
Storm Drainage Improvements:
This 2.45-acre project is located in one drainage basin. This drainage basin will convey stormwater
from the roadway to the water quality vaults and on to the infiltration galleries. The total area of the basin
is 0.8415 acres. This area is the roadway and drainage area. The remainder of the project will be
pervious surfaces. All home roof drains will be connected to drywells. In the following basin
summarizes all impervious area for the homes have been disregarded. These areas will be infiltrated at
the home location.
Pre-Development Basin Summary
Basin A (Ac)
Impervious 0.00
Disturbed Pervious 0.00
Undisturbed Pervious 2.45
Total 2.45
Post-Development Basin Summary
Basin A (Ac)
Impervious 0.72
Disturbed Pervious 0.12
Open Space Area 0.15
Roofs draining, to Drtiwells 1.45
Total 2.45
Storm water Treatment:
Basin A:
This basin includes all right of way area between the entrance at Vancil Road and end of the cul-
de-sac. This new roadway will sheet flow into the catch basins located at the low points of the
roadway and the pipe system will convey the storm water to the storm water facility. Storm water
will then be treated using wet tanks located in the open space.
The wet tank volume has been determined to be 2.5% of the impervious area tributary to the
system.
Treatment Area Summa
Basin # Impervious Area Disturbed Pervious
Area Treatment
Re uired Treatment
Provided
Basin 0.72 ac. 0.12 ac. 2791 allons 4,500 allons
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Short Plat of Timber Estates, Drainage Report
Storm water Storage:
Preliminary storage requirements were based on the Soil Survey of Thurston County. A design
infiltration rate of 20 inches/hour was used for this preliminary design. The DDECM required 3000
cf of storage for each acre of impervious area and 1000 cf of storage for each acre of disturbed
pervious area. This is based on an infiltration rate of 20 in/hr.
Basin A:
Treated runoff from the wet tank will flow into an infiltration gallery located along side the wet
tank. This gallery is 6' wide X 6' deep and 125 feet long. This galley will have a 36" perforated
pipe running the length of the gallery, cleanouts at ends and corners and wrapped with filter fabric.
The volume of the gallery has been calculated to be 18.64 cubic feet per a foot. This is utilizing a
volume factor of 40% for the washed rock.
The infiltration gallery has a volume of 2330 cubic feet, which exceeds the minimum volume of
2285 cubic feet.
Stora a Ca aci Summa
Basin # Impervious Area Disturbed Pervious
Area Storage Volume
Re uired Storage Volume
Provided
Basin 0.72 ac. 0.12 ac. 2,285 c.f. 2,330 c.f.
(All acre numbers have been rounded to the nearest hundredth of an acre. Actual volume has been
calculated using the exact numbers)
SECTION 2 -EXISTING CONDITIONS
This site is an open pasture with scotch bloom. This area has fee trees located around the site. The
remainder of the site has no trees and is relatively flat. The existing topographic information shows the
site with slopes of 1 % to 3% in isolated areas however overall this site is flat.
There are no drainage channels within or near the site and no off-site drainage enters the site. There are
no creeks, lakes, ponds, wetlands, ravines, gullies, steep slopes, springs, or any other environmentally
sensitive areas on-site or down gradient of the property.
SECTION 3 -INFILTRATION RATES/SOILS REPORT
The Soil Conservation Service (SCS) Soil Survey of Thurston County maps the on-site soils as a
Spanaway gravelly sandy loam (0-3% slopes) and Spanaway-Nisqually complex (2-10% slopes). This
soil type features Hydrologic Group A characteristics. Refer to Appendix V for the SCS Soils Map.
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Short Plat of Timber Estates, Drainage Report
SECTION 4 -WELLS AND SEPTIC SYSTEMS
The existing site has asingle-family well located on future lot no. 1 and will be decommissioned before
construction is completed.
The existing site had an on-site septic system located on future lat no. 1 and has been abandoned during
removal of the existing house.
No abandoned septic systems were identified during the site investigation. Any additional septic systems
found shall be removed in accordance with Thurston County Department of Health Standards.
SECTION 5 -FUEL TANKS
No fuel tanks were located during the site investigation. Based on information provided by the project
developer, no buried fuel tanks are known to exist. Additionally, a review of the DOE's Leaking
Underground Storage Tanks (LUST) list did not indicate any existing or abandoned fuel tanks on the
project site.
SECTION 6 -SUB-BASIN DESCRIPTION
This project has been designed to infiltrate all stormwater produced by this site. There will be no runoff
from the project site for the 100-year, 24-hour storm event. There is no significant off-site runoff to the
project site.
Handling of hazardous materials is not anticipated on the project site.
SECTION 7 -ANALYSIS OF 100 YEAR FLOOD
The project site does not iay adjacent to or contain a major stream on-site; therefore it has not been
identified as a flood hazard area. The FEMA Firm Map for this site shows this site outside thee 100-year
flood plain.
SECTION 8 -AESTHETIC CONSIDERATIONS FOR STORMWATER FACILITIES
All disturbed areas will be vegetated. The stormwater infiltration facilities have been designed to be
located underground. Aesthetics of facilities will be in keeping with similar subdivisions in the area.
SECTION 9 -DOWNSTREAM ANALYSIS AND FACILITY SIZING
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Short Plat of Timber Estates, Drainage Report
There will be no runoff from the project site, during the 100-year, 24-hour storm event, therefore, no
downstream analysis is necessary.
SECTION 10 -COVENANTS, DEDICATIONS, EASEMENTS
The on-site storm drainage facilities, including treatment and detention ponds, catch basins, and pipes will
require routine maintenance. A draft maintenance agreement between the owner and City of Yelm is
included in Appendix VII that will allow the jurisdiction access to facilities. The owner is responsible for
performing regular maintenance of the storm drainage facilities. City of Yelm will provide technical
assistance at the owner's request.
SECTION 11-PROPERTY OWNERS ASSOCIATION ARTICLES OF INCORPORATION
Maintenance of the private storm drainage facilities will be performed by the owner and/or their
representative until the homeowners association is established and takes over the maintenance.
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Short Plat of Timber Estates, Drainage Report
PART II EROSION CONTROL REPORT
SECTION 1 -CONSTRUCTION SEQUENCE AND PROCEDURE
This proposed subdivision includes an erosion control plan designed to contain silt and soil within the
project boundaries during construction, and permanent erosion control afterward. Erosion/sedimentation
control is achieved by a combination of structuraUvegetation 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 filter fabric fencing and construction fence. (As Required)
2, Rough grade roadway and drainage swales.
3. Construct infiltration galleries.
4. During November 1 through March 31, all disturbed areas greater than 5,000 sf that are to
be left unworked for more than twelve (12) hours shall be stabilized by one of the
following: mulch, sodding or plastic covering.
S. Install storm drainage piping.
6. Provide catch basin inlet protection by installing filter fabric under grates of all inlets to
drainage system.
7. Landscape, sod and/or seed and mulch all disturbed areas.
8. Flush storm drainage system.
9. Maintain all erosion control facilities until the entire site is stabilized and silt runoff ceases.
SECTION 2 -TRAPPING SEDIl4IENT
The soils on-site belong to the Spanaway group and have low erosion potential according to the SCS. In
those areas where the parcel slopes toward the adjoining property, filter fabric fence will be used to
control erosion and off-site runoff.
The contractor will not be allowed to leave disturbed areas greater than 5,000 sf uncovered during the
rainy season from November 1 through April 30. Soil shall be stabilized within 48 hours after stop of
work in any area that will remain unworked for 30 days or more. Mulch, sodding or plastic covering will
be used to prevent erosion in these areas. During the dry season from May 1 to October 30, exposed soils
should be stabilized within 30 days.
During construction, the contractor will be required to install filter fabric fencing as needed and limit site
access to one location. Catch basin protection shall be provided by installing filter fabric under grates of
all inlets to drainage system. All disturbed/exposed soils shall be covered with straw or mulch to prevent
erosion in these areas.
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Short Plat of Timber Estates, Drainage Report
SECTION 3 -PERMANENT EROSION CONTROL & SITE RESTORATION
All disturbed areas will be asphalted or seeded with grass or natural vegetation.
SECTION 4 -GEOTECHNICAL ANALYSIS AND REPORT
The proposed infiltration facilities are not located within 50' of a slope 15% or greater; therefore, a
Geotechnical Analysis and report addressing slope stability was not deemed necessary.
SECTION 5 -INSPECTION SEQUENCE
In addition to County inspections, the Project Engineer shall inspect the facilities related to stormwater
treatment, erosion control, storage and conveyance during construction. At a minimum, the following
items shall be inspected at the time specified:
The erosion control facilities shall be inspected before the start of construction to ensure
the following structures are in place:
a. Filter Fabric Fences
b. Catch Basin Filters
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.
b. Catch Basins
c. Infiltration Galleries
The permanent site restoration measures shall be inspected after landscaping is completed.
A final inspection will be performed to check final grades, settings of control structures and all necessary
information to complete Engineer's Construction Inspection Report to meet Thurston County's
requirements for inspection and reporting.
SECTION 6-CONTROL OF POLLUTANTS OTHER THAN SEDIMENTS
Washout from concrete trucks shall not be dumped into the storm drain, or onto soil and pavement, which
carries stormwater runoff. It will 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 washdown area for
equipment and concrete trucks.
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Short Plat of Timber Estates, Drainage Report
PART III MAINTENANCE PLAN
SECTION 1-REQUIRED MAINTENANCE
The following pages contain maintenance needs for most of the components that are part of the
drainage system. A checklist should be completed for all system components on the following
schedule:
M Monthly from November through April.
A. Once in late summer (preferably September).
S. 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 looked for each time an inspection was
performed. Add comments or problems found and actions taken. Keep these "Checked" sheets on
file, as they will be used to write the 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 inspections.
The jurisdiction is available for technical assistance. Please do not hesitate to call, especially if a
potential problem exists.
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Short Plat of Timber Estates, Drainage Report
ATTACHMENT "A": MAINTENANCE PROGRAM
Maintenance Checklist for Conveyance Systems (Pipes and Swales)
Frequency Drainage ~ Problem Conditions to Check For Conditions That
System Should Exist
Feature
M.S. Pipes ~ Sediment & Accumulated sediment Pipe cleaned of all
debris that exceeds 20% of the sediment and debris.
diameter of the i e.
M ~ Vegetation Vegetation that reduces All vegetation
free movement of water removed so water
throu h i es. flows freel .
A ~ Damaged Protective coating is Pipe repaired or
(rusted, bent damaged, rust is causing replaced.
or crushed) more than 50%
deterioration to any part
of i e.
M J Any dent that Pipe repaired or
significantly impedes replaced.
flow (i.e., decreases the
cross-section area of pipe
b more then 20%).
M ~ Pipe has major cracks or Pipe repaired or
tears allowing replaced.
oundwater leaka e.
M.S. Swales ~ Trash & Dumping of yard wastes Remove trash and
debris such as grass clippings debris and dispose as
and branches into swale. prescribed by County
Unsightly accumulation Waste Management
of non-degradable Section.
materials such as glass,
plastic, metal, foam and
coated a er.
M ~ Sediment Accumulated sediment Swale cleaned of all
buildup that exceeds 20% of the sediment and debris
design depth. so that it matches
design.
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Short Plat of Timber Estates, Drainage Report
M ~ Vegetation Grass cover is sparse and Aerate soils and
. not growing weedy or areas are reseed and mulch bare
or overgrown with woody areas. Maintain grass
overgrown vegetation. height at a minimum
of 6" for best
stormwater treatment.
Remove woody
growth, recontour and
reseed as necessa
M,S ~ Erosion See ponds checklist See ponds checklist
damage to
slo es
M J Conversion Swale has been filled in If possible, speak with
by or blocked by shed, homeowner and
homeowner woodpile, shrubbery, etc. request that swale
to area be restored.
incompatible Contact City to report
use problem if not
rectified voluntaril .
A ~ Swale does Water stands in Swale or A survey may be
not drain flow velocity is very needed to check
slow. Stagnation occurs. grades. Grades need
to be in 1 % range if
possible. If grade is
less than 1 %,
underdrains may need
to be installed.
Ifyou 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 = ARer major storms
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Short Plat of Timber Estates, Drainage Report
ATTACHMENT "A": MAINTENANCE PROGRAM
Maintenance Checklist for Catch Basins and Inlets
Feature Drainage ~ Problem Conditions to Check For Conditions That
System Should Exist
Feature
M.S. General ~ Trash, debris Trash or debris in front No trash or debris
and sediment of the catch basin located immediately in
in or on basin opening is blocking front of catch basin
capacity by more than opening. Grate is kept
10%. clean and allows water
to enter.
M ~ Sediment or debris (in No sediment or debris
the basin) that exceeds in the catch basin.
1/3 the depth from the Catch basin is dug out
bottom of basin to invert and clean.
of the lowest pipe into or
out of the basin.
M.S. ~ Trash ar debris in any Inlet and outlet pipes
inlet or pipe blocking free of trash or debris.
more than 1/3 of it's
hei ht.
M ~ Structural Comer of frame extends Frame is even with
damage to more than 3!4" past curb curb.
frame and/or face into the street (if
top slab applicable).
M ~ Top slab has holes larger Top slab is free of
than 2 inches or cracks holes and cracks.
wider than 1/4" (intent is
to make sure all material
is running into the
basin).
M ~ Frame not sitting flush Frame is sitting flush
on top slab, i.e., on top slab.
separation of more than
3/4" of the frame from the
to slab.
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Short Plat of Timber Estates, Drainage Report
A ~ Cracks in Cracks wider than 1/2" Basin replaced or
basin and longer than 3', any repaired to design
walls bottom evidence of soil particles standards. Contact a
entering catch basin professional engineer
through cracks or for evaluation.
maintenance person
judges that structure is
unsound.
A ~ Cracks wider than 1/2" No cracks more than
and longer than 1' at the 1/4" wide at the joint
joint of any inlet/outlet of inlet/outlet pipe.
pipe or any evidence of
soil particles entering
catch basin through
cracks.
A ~ Settlementlmi Basin has settled more Basin replaced or
s-alignment than 1" or has rotated repaired to design
more than 2" out of standards. Contact a
alignment. professional engineer
for evaluation.
M.S. ~ Fire hazard or Presence of chemicals No color, odor or
other such as natural gas, oil sludge. Basin is dug
pollution and gasoline. out and clean.
Obnoxious color, odor or
stud a noted.
M.S. ~ Outlet pipe is Vegetation or roots No vegetation or root
clogged with growing in inlet/outlet growth present.
vegetation pipe joints that is more
than 6" tall and less than
6" a art.
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
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Short Plat of Timber Estates, Drainage Report
ATTACHMENT "A": MAINTENANCE PROGRAM
Maintenance Checklist for Grounds (Landscaping}
Frequency Drainage Problem Conditions to Check Conditions That
System For Should Exist
Feature
M General Weeds Weeds growing in Weeds present in less
(nonpoisonou more than 20% of the than 5% of the
s) landscaped area (trees landscaped area.
and shrubs onl ).
M Safety hazard Any presence of poison No poisonous
ivy or other poisonous vegetation or insect
vegetation or insect nests present in
nests. landsca ed area.
M.S. Trash & Dumping of yard Remove trash and
debris wastes such as grass debris and dispose as
buildup in clippings and branches. prescribed by City
open space Unsightly Waste Management
accumulation of non- Section.
degradable materials
such as glass, plastic,
metal, foam and coated
pa er.
M Missing or Any defect in the fence Fence is mended or
broken or screen that permits shrubs replaced to form
parts/dead easy entry to a facility. a solid barrier to entry.
shrubbe
M.S. Erosion Erosion has resulted in Replace soil under
an opening under a fence so that no
fence that allows entry opening exceeds 4" in
by people or pets. height. Causes of
erosion identified and
steps taken to slow
down and/or spread out
the water. Eroded
areas are filled,
contoured, and seeded.
M Unruly Shrubbery is growing Shrubbery is trimmed
vegetation out of control or is and weeded to provide
infested with weeds. appealing aesthetics.
Do not use chemicals
to control weeds.
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Short Plat of Timber Estates, Drainage Report
A Trees and Damage Limbs or parts of trees Trim trees/shrubs to
shrubs or shrubs that are split restore shape. Replace
or broken which affect trees/shrubs with
more than 25% of the severe damage.
total foliage of the tree
or shrub.
M Trees or shrubs that Replant tree, inspecting
have been blown down for injury to stem or
or knocked over. roots. Replace if
severely dam ed.
A Trees or shrubs which Place stakes and
are not adequately rubber-coated ties
supported or are around young
leaning over, causing trees/shrubs for
ex osure of the roots. su ort.
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
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Short Plat of Timber Estates, Drainage Report
ATTACHMENT "A": MAINTENANCE PROGRAM
Maintenance Checklist for Ponds
Frequency Drainage Problem Conditions to Check Conditions That
System For Should Exist
Feature
M,S General Trash & Clumping of yard Removed trash and
debris buildup wastes such as grass debris and dispose as
in pond. clippings and prescribed by City
branches into basin. Waste Management
Unsightly Section
accumulation of
nondegradable
materials such as
glass, plastic, metal,
foam and coated
a er..
M,S Trash rack Bar screen over outlet Replace screen.
plugged or more than 25% Remove trash and
missing covered by debris or debris and dispose as
missing. prescribed by City
Waste Management
Section.
M Poisonous Any poisonous Remove poisonous
vegetation vegetation which may vegetation. Do not
constitute a hazard to spray chemicals on
the public. Examples vegetation without
of poisonous obtaining guidance
vegetation include: from the Cooperative
tansy ragwort, poison Extension Service
oak, stinging nettles, and approval from
devilsclub. the Ci
M,S Fire hazard or Presence of chemicals Find sources of
pollution such as natural gas, oil pollution and
and gasoline, eliminate them.
obnoxious color, odor Water is free from
or sludge noted. noticeable color,
odor or
contamination.
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Short Plat of Timber Estates, Drainage Report
M Vegetation For grassy ponds, For grassy ponds,
not growing grass cover is sparse selectively thatch,
or is and weedy or is aerate, and reseed
overgrown overgrown. For ponds. Grass cutting
wetland ponds, plants unnecessary unless
are sparse or invasive dictated by
species are present. aesthetics. For
wetland ponds,
handplan nursery-
grown wetland plants
in bare areas.
Contact the
Cooperative
Extension Service for
direction on invasive
species such as
purple loosestate and
reed canary grass.
Pond bottoms should
have uniform dense
coverage of desired
lant s ecies.
M Rodent holes Any evidence of Rodents destroyed
rodent holes if facility and dam or berm
is acting as a dam or repaired. Contact the
berm, or any evidence Thurston County
of water piping Health Department
through dam or berm for guidance.
via rodent holes.
M Insects When insects such as Insects destroyed or
wasps and hornets removed from site.
interfere with Contact Cooperative
maintenance Extension Service for
activities, or when guidance.
mosquitoes become a
nuisance.
A Tree growth Tree growth does not Trees do not hinder
allow maintenance maintenance
access or interferes activities.
with maintenance Selectively cultivate
activity (i.e., slope trees such as alders
mowing, silt removal, for firewood.
or equipment
movements). If trees
are not interfering
with access, leave
trees alon .
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Short Plat of Timber Estates, Drainage Report
M Side slopes Erosion on Check around inlets Find causes of
of pond berms or at and outlets for signs erosion and eliminate
entrance/exit. of erosion. Check them. Then slopes
berms for signs of should be stabilized
sliding or settling. by using appropriate
Action is needed erosion control
where eroded damage measure(s); e.g., rock
over 2 inches deep reinforcement,
and where there is planting of grass,
potential for continued compaction.
erosion.
M Storage area Sediment Accumulated Sediment cleaned out
buildup in sediment that exceeds to designed pond
pond 10% of the designed shape and depth;
pond depth. Buried or pond reseeded if
partially buried outlet necessary to control
structure probably erosion.
indicates significant
sediment deposits.
A Pond dikes Settlements Any part of dike Dike should be build
which has settled 4 back to the design
inches lower than the elevation.
desi n elevation.
A Emergency Rock missing Only one layer of rock Replace rocks to
overflow/ exists above native design standards.
Spillway soil in area 5 square
feet or larger, or any
exposure of native
soil.
One Time Emergency Overflow Side of pond has no Contact City for
overflow/ missing area with large rocks guidance.
Spillway to handle 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
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Short Plat of Timber Estates, Drainage Report
SECTION 2 -RESPONSIBLE ORGANIZATION
The property owner (and successors) is responsible for the operation and maintenance of on-site drainage
facilities. See the residential maintenance agreement in Appendix VII.
SECTION 3 -VEGETATION MANAGEMENT PLAN
All disturbed pervious areas within the site will be seeded to provide erosion control and an aesthetically
pleasing environment.
SECTION 4 -SOURCE CONTROL
Warning signs (e.g., "Dump No Waste -Drains to Ground Water") will be painted or embossed on or
adjacent to all storm drain inlets and will be repainted periodically as necessary.
Page 19