HomeMy WebLinkAboutConstruction Stormwater Site Plan - PLN General - 1/14/2021 MASON COUNTY
PUBLIC WORKS DIRECTOR/COUNTY ROAD ENGINEER
N G Shelton, Washington 98584
DATE: January 14, 2021
INTER-DEPARTMENTAL COMMUNICATIONS
TO: Michael MacSems PARCEL # 12221-43-00100
FROM: Fred Perryman — E&C Asst Manager PERMIT #: FPA
SUBJECT: Stormwater Site Plan (SSP) NAME: Aaron Valencia
Michael:
The stormwater site plan for Aaron Valencia off of SR 302 was received and reviewed by Public Works.
The proposal is to build a 2,500 square foot structure along with a driveway for a total of 10,850 SF of
impervious surface. The stormwater runoff from the structure will be tight lined to an infiltration bed. The
runoff from the driveway will sheet flow thru a vegetated filter strip. This stormwater drainage plan was
found to be acceptable with the following conditions.
Permit Conditions:
• A Declaration of Covenants Associated with Privately Maintained Storm Drainage
Facilities (O&M) should be executed and recorded with Mason County prior to permit
being finalized.
• The stormwater drainage plan should be incorporated into the site-plans and be a
condition of permit issuance.
• A record drawing shall be recorded with the county upon completion of the project.
Adequate erosion and sediment control features need to be implemented during land disturbing
activities to protect neighboring properties and State waters from adverse stormwater runoff
impacts. The migration or release of silty water or mud from the applicant's property will be
considered a violation of County and State water quality protection regulations.
Please feel free to contact me at 625 if you have any questions.
Si cerel ,
Fred Perry n
E&C Asst Manager
" l�' RECEIVED
MASON COUNTY
COMMUNITY SERVICES NOV 3 0 2020
Building,Planning,Environmental Health,Community Health
615 W. Alder Street
Construction Stormwater Pollution Prevention Plan Checklist
Project Name: Valencia Single Family Residence
Parcel #'s. 12221-43-00100
County Project No.:
Author of Report: Envirotech Engineering P.L.L.C.
Section I — Construction SWPPP Narrative
Construction Stormwater Pollution Prevention Elements
1. x Describe how each of the Construction Stormwater Pollution Prevention Elements
have been addressed through the Construction SWPPP.
2. x Identify the type and location of BMPs used to satisfy the required element.
3. x Provide written justification identifying the reason an element is not applicable to the
proposal.
Thirteen Required Elements—Construction Stormwater Pollution Prevention Plan
1. x Mark Clearing Limits
2. x Establish Construction Access
3. x Control Flow Rates
4, x Install Sediment Controls
5. x Stabilize Soils
6. x Protect Slopes
7. x Protect Drain Inlets
8. x Stabilize Channels and Outlets
9. x Control Pollutants
10, x Control De-Watering
11. x Maintain BMPs
12. x Manage the Project
13. x Protect Low Impact Development BMPs
X d. Settleability
X e, Permeability
X f. Depth
X g. Texture
X h. Soil Structure
Erosion Problem Areas
1. X Description of potential erosion problems on site.
Construction Phasing
1. X Construction sequence
2. X Construction phasing (if proposed)
Construction Schedule
1. X Provide a proposed construction schedule.
2. X Wet Season Construction Activities
a. Proposed wet season construction activities.
_ b. Proposed wet season construction restraints for environmentally sensitive/critical
areas.
Financial/Ownership Responsibilities
1. X Identify the property owner responsible for the initiation of bonds and/or other
financial securities.
2. X Describe bonds and/or other evidence of financial responsibility for liability
associated with erosion and sedimentation impacts.
Engineering Calculations
1. X Provide Design Calculations.
a. Sediment Ponds/Traps
b. Diversions
_c. Waterways
X d. Runoff/Stormwater Detention Calculations
Page 3 of 5
Construction Stormwater Pollution Prevention Plan
Valencia Single Family Residential Property
4361 E State Route 302, Belfair
Parcel No. 12221-43-00100
Mason County, Washington
November 10, 2020
Project 920169
Prepared For:
Aaron Valencia
6828 A Street
Tacoma, Washington 98408
Phone: 206-849-0204
Prepared By:
Envirotech Engineering
PO Box 984
Belfair, Washington 98528
Phone: 360-275-9374
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TABLE OF CONTENTS
1.0 INTRODUCTION.................................................................................................................................1
PROJECTDESCRIPTION................................................................................................................................I
EXISTINGSITE CONDITIONS........................................................................................................................I
ADJACENTAREAS.......................................................................................................................................1
SOILS..........................................................................................................................................................2
EROSIONPROBLEM AREAS.........................................................................................................................2
CONSTRUCTION SCHEDULE.........................................................................................................................3
ENGINEERING CALCULATIONS....................................................................................................................3
2.0 SPECIFIC CONSTRUCTION SWPPP ITEMS.................................................................................3
2.1 ELEMENT 1-PRESERVE VEGETATION/MARK CLEARING LIMITS.........................................................3
2.2 ELEMENT 2-ESTABLISH CONSTRUCTION ACCESS...............................................................................3
2.3 ELEMENT 3-CONTROL FLOW RATES...................................................................................................4
2.4 ELEMENT 4-INSTALL SEDIMENT CONTROLS.......................................................................................4
2.5 ELEMENT 5-STABILIZE SOILS.............................................................................................................4
2.6 ELEMENT 6-PROTECT SLOPES.............................................................................................................4
2.7 ELEMENT 7-PROTECT DRAIN INLETS..................................................................................................4
2.8 ELEMENT 8-STABILIZE CHANNELS AND OUTLETS..............................................................................5
2.9 ELEMENT 9-CONTROL POLLUTANTS...................................................................................................5
2.10 ELEMENT 10-CONTROL DEWATERING..............................................................................................5
2.11 ELEMENT I I-MAINTAIN BMP'S.......................................................................................................5
2.12 ELEMENT 12-MANAGE THE PROJECT................................................................................................6
2.13 ELEMENT 13-PROTECT LOW IMPACT DEVELOPMENT BMP'S..........................................................6
1.0 Introduction
Envirotech Engineering (Envirotech) has completed this construction stormwater pollution
prevention plan (SWPPP) in conjunction with the stormwater management plan for for Valencia
Single Family Residence located at 4361 E State Route 302 (Parcel 12221-43-00100) in Mason
County,Washington.
Best Management Practices (BMP's) selected for this project includes a stabilized construction
entrance and silt fencing. It is our opinion that these selected BMP's adequate for preventing
significant construction stormwater pollution from leaving the project site, and meets the intent of
the Stormwater Manual. The following 13 items have been addressed per the prevailing
Stormwater Manual.
Project Description
Information pertaining to the development of this project was provided by the proponent of the
property. The proposed development includes a Single Family Residence, driveway, on-site
septic system,and associated stormwater management facilities.
It is anticipated that the roof area will encompass 2500 sf in size, and road/ driveways will
encompass approximately 8350 sf in size for a total of 10850 sf proposed impervious surface
area. The total land area that is anticipated to be disturbed as a result of development is 1.45
acres. Cut and fill quantities were approximated to be 12 cubic yards(cy)and 12 cy,respectively.
Existing Site Conditions
The property is accessed from E State Route 302, an existing paved highway in unincorporated
Mason County. The Project is currently undeveloped, with some clearing on-site. Vegetation is
typical of the Pacific Northwest.
E State Route 302 extends in a north-south direction to the west of the property. Beyond the
property, rural residential development exists.
Descending slopes exceeding 15%are located on and beyond the property. Average slope grades
are approximately 20%with a vertical relief of approximately 120 feet.
Adjacent Areas
The area of land that contributes stormwater runoff to the proposed development areas of the
property is minimal.The property appears to be the largest contributor of stormwater runoff.
The natural drainage from the property is directed to the west end of the property. The water
travels by sheet flow to a county drainage ditch located to the west of the property. The drainage
ditch appears to infiltrate into the existing subsurface.
Envirotech Engineering SWPPP
PO Box 984 page 1 Parcel 1222143-00100
Belfair,Washington 98528 Kitsap County,Washington
Ph. 360-275-9374 April 11,2019
Critical Areas
Other than the aforementioned moderate slopes located on the property, critical areas were not
observed within the vicinity of the project. This project is not anticipated to disturb any critical
area.
soils
Information on infiltration rates and soil conditions pertaining to the Project was accomplished by
Envirotech. Selected information pertaining to the drainage aspect of the project is provided
below.
The following subsurface conditions are estimated descriptions of the Project subgrade utilizing
information from the depth of penetration at all testing, sampling, observed and investigated
locations. Soils for this project were described utilizing the Unified Soil Classification System
(USCS). Using the USCS in conjunction with estimated relative densities and other anticipated
engineering properties of the soil, susceptibility for potential landslides, erosion and seismic
hazards may be assessed.
The project is primarily composed of undisturbed, native soils, without indications of substantial
fill. Competent bearing soils were encountered at 12 inches below the existing native ground
surface in locations where the ground was probed. For engineering purposes, these native soils
consist of distinguishable layers,as presented below.
Soils within the upper 4 feet of natural ground were observed to be primarily moist, brown silty
sand with gravel and some clay(SM).
According to the "Soil Survey of Mason County," by the United States Department of
Agriculture, Soil Conservation Service (SCS), the site soils are described as Alderwood gravelly
sandy loam, Ab,with 8%- 15% slopes and Everett very gravelly sandy loam, Eh and Ek,with 8%
-30%slopes.
Based on the fines content, erodibility of the site soils is considered to be medium. Based on the
fines content and fraction of clay within the fines content, settleability of the site soils is expected
to be fast. Permeability is expected to be moderate for this site due significance of moderate
density,and fine-grained soils.
From the water well report(s) and knowledge of the general area, permanent groundwater is at
least 50 feet directly below the property at the building pad location.
Erosion Problem Areas
There are no identified or mapped erosion hazard areas for this property. The soil characteristics
provide a low to moderate erodibility factor.
Construction Phasing
Envirotech Engineering SWPPP
PO Box 984 page 2 Parcel 12221-43-00100
Belfair,Washington 98528 Kitsap County,Washington
Ph. 360-275-9374 April 11,2019
Construction phasing for this project is not expected.Upon finishing the access roads,developing
single family residences will be considered future projects.
Construction Schedule
Construction of the project may occur as early as November 2020. Wet season erosion control is
not likely required for this project. However, wet season construction constraints are not
necessary for critical areas.
Engineering Calculations
Standard sediment ponds and traps were not utilized for this project.However, sedimentation due
to construction runoff is anticipated to be retained on site. Significant diversions and waterways
were not utilized for this project. Silt fencing is deemed adequate for this project,and calculations
are not required for this erosion control.
2.0 Specific Construction SWPPP Items
The following 13 items have been addressed per the prevailing Stormwater Manual.
2.1 Element 1-Preserve Vegetation/Mark Clearing Limits
Before beginning land disturbing activities, including clearing and grading, clearing limits,
sensitive areas and their buffers shall be clearly delineated on-site. This includes delineating trees
that are to be preserved within the construction area. Construction activities are not permitted
beyond the designated clearing limits without prior approval.
Retain the duff layer, native top soil, and natural vegetation in an undisturbed state to the
maximum degree practicable.
2.2 Element 2-Establish Construction Access
Construction access is designated as the ingress/ egress connecting to E State Route 302. One
construction access is allowed for this project. Stabilize the construction access with rock per the
stormwater plans in order to minimize tracking of sediments off-site. If the stabilized construction
entrance proves ineffective,locate wheel wash or tire baths on-site.If sediment is tracked off-site,
clean the affected roadway thoroughly at the end of each day, and more frequent as necessary.
Remove sediments by any means necessary, and transport the sediment to a controlled sediment
disposal area. After sediment removal, conduct street washing, and control wash water by
pumping back on-site,or otherwise prevent it from discharging into systems tributary to waters of
the State.
Envirotech Engineering SWPPP
PO Box 984 page 3 Parcel 1222143-00100
Belfair,Washington 98528 Kitsap County,Washington
Ph. 360-275-9374 April 11,2019
2.3 Element 3-Control Flow Rates
At all times, flow rates shall be controlled for this project. Natural drainage patterns shall be
protected as much as possible during construction, and concentrated flow should not be
permitted, unless directed to an engineered drainage facility. Protect downstream waterways and
properties from associated discharge of turbid waters.
2.4 Element 4-Install Sediment Controls
Sediment discharges from the project site must be minimized. Sediment controls deemed
adequate for this project is temporary silt fencing, and shall be located downslope from all
disturbed areas.
If sediment control is not working as intended, additional controls such as sediment traps, hay
bales,filters,or other standard controls will be necessary.
2.5 Element S-Stabilize Soils
Soil stabilization is not necessary for this project. Temporary seeding and permanent soil
stabilization requirements are provided in the erosion control section of the design drawings.
Always minimize the area of exposed soils during construction, including disturbance on steep
slopes. In addition, soil compaction should be minimized, and topsoil preserved as much as
possible.
Soils shall not remain exposed and unworked for more than 7 days during the dry season(May 1
—September 30),and more than 2 days during the wet season(October 1 —April 30).
2.6 Element 6-Protect Slopes
Slopes exceeding 10%are expected near the entrance from E State Route 302. Slope protection is
not required for this project.
2.7 Element 7-Protect Drain Inlets
There are no existing drain inlets close to the project that would be influenced by the
construction.Newly installed catch basins and other inlets, shall be protected from runoff siltation
via silt fence inlet barriers, inserts, or other appropriate means. Clean or remove and replace inlet
protection devices when sediment has filled one-third of the available storage (unless a different
standard is specified by the product manufacturer).
Envirotech Engineering SWPPP
PO Box 984 page 4 Parcel 1222143-00100
Belfair,Washington 98528 Kitsap County,Washington
Ph. 360-275-9374 April 11,2019
2.8 Element 8-Stabilize Channels and Outlets
There are no Channels of Outlets planned for this project.
2.9 Element 9-Control Pollutants
Pollution generated from construction must be controlled at all times. Control of pollutants other
than sediments includes the following:
• All pollutants other than sediments shall be handled and disposed of in a manner that
does not cause contamination of stormwater.
• Cover, containment and protection from vandalism shall be provided for all chemicals,
liquid products,petroleum products,and non-inert wastes present on the project site.
• Maintenance and repair of heavy equipment and vehicles involving oil changes,
hydraulic system drain down, solvent and de-greasing cleaning operations, fuel tank drain
down and removal, and other activities which may result in discharge or spillage of
pollutants to the ground or into stormwater runoff must be conducted using spill prevention
measures, such as drip pans.Contaminated surfaces shall be cleaned immediately following
any discharge or spill incident. Emergency repairs may be performed on-site using
temporary plastic placed beneath and,if raining,over the vehicle.
• Wheel wash or tire bath wastewater shall be discharged to a separate on-site treatment
system or to the sanitary sewer,if available.
• Application of agricultural chemicals including fertilizers and pesticides shall be
conducted in a manner, and at application rates that will not result in loss of chemical to
stormwater runoff. Manufacturers' recommendations for application rates and procedures
shall be followed.
2.10 Element 10-Control Dewatering
Although dewatering will not be likely for this project, special provisions are required to be
followed when dewatering. The outlet for dewatering shall be located in a position as to prevent
sediments and pollution from leaving the site.This may be accomplished by pumping water into a
sedimentation pond,or other standard control.
2.11 Element 11 -Maintain BMP's
All BMP's must be inspected and maintained in order to assure continued performance of their
intended function. Remove all temporary erosion and sediment control BMP's within 30 days
after achieving final site stabilization or after the temporary BMP's are no longer needed.
Inspection and maintenance for this project includes the following:
Envirotech Engineering SWPPP
PO Box 984 page 5 Parcel 12221-43-00100
Belfair,Washington 98528 Kitsap County,Washington
Ph. 360-275-9374 April 11,2019
Stabilized Construction Entrance
The stabilized construction entrance shall be inspected at reasonable increments. Increased usage
of the construction entrance warrants more frequent inspections. Additional rock shall be added
periodically to maintain proper function of the pad.
Silt Fence
All silt fencing,if used, shall be inspected immediately after each rainfall and at least daily during
prolonged rainfall.Any required repairs shall be made immediately.
Permanent Vegetation
Permanent vegetation shall initially be inspected regularly to insure establishment and healthy
growth. Once established, vegetation may need to be periodically fertilized for continuous
growth.Vegetation shall be re-established in areas, if necessary.
While active construction is in process,all temporary erosion and sediment control facilities shall
be inspected and immediately maintained if necessary per the requirements provided above. In
the event that construction activities are discontinued for at least 4 consecutive days, the owner
shall be responsible for the inspection, and immediate maintenance if necessary, of all temporary
erosion and sediment control facilities immediately after storm events, and at least once every 7
days.
In addition to the aforementioned inspection and maintenance schedule, the owner shall install
additional erosion and sediment control facilities if proposed erosion and sediment control
measures prove to be inadequate.
2.12 Element 12-Manage the Project
Inspection, maintenance, and financial liability of all temporary/ permanent erosion and
sedimentation control facilities shall ultimately be the responsibility of the current property
owner. All construction facilities and BMP's shall be assured continued performance of their
intended function. Since less than 1 acre is planned to be disturbed, a Certified Erosion and
Sediment Control Lead (CESCL) is not required. Currently, the designated manager for this
project is:
Aaron Valencia
6828 A Street
Tacoma, Washington 98408
(206)849-0204
2.13 Element 13—Protect Low Impact Development BMP's
Prevent compaction of vegetated flow paths delineated for this project,and other low impact
development BMP's that may be associated with this project.This should be done by excluding
construction equipment and foot traffic.
Envirotech Engineering SWPPP
PO Box 984 page 6 Parcel 12221-43-00100
Belfair,Washington 98528 Kitsap County,Washington
Ph. 360-275-9374 April 11,2019
14 w
Maintenance and Operation Manual
For
Valencia Single Family Residential Property
4361 E State Route 302, Belfair
Parcel No. 12221-43-00100
Mason County, Washington
November 10, 2020
Project#20169
Prepared For:
Aaron Valencia
6828 A Street
Tacoma, Washington 98408
Phone: 206-849-0204
Prepared By:
Envirotech Engineering
PO Box 984
Belfair, Washington 98528
Phone: 360-275-9374
C LY D,S
�SS�ONAL
11/10/20
Introduction
Envirotech Engineering, PLLC (Envirotech) has completed this maintenance manual for
proposed Valencia Single Family Residence located at 4361 E State Route 302 (Parcel 12221-43-
00100)in Mason County,Washington.
Manual Purpose
The purpose of this manual is to provide the property owner with a specific maintenance
plan in order to ensure the continued proper operation of all stormwater management
facilities associated with this project. Lack of maintenance could lead to local flooding,
water damage, excess pollution, and/ or costly repairs or replacements of property or
drainage systems.
Maintenance Responsibilities
Facility maintenance is ultimately the responsibility of the current property owner. At the
time of completing the stormwater design, dated November 10, 2020, stormwater
maintenance responsibility for this property belongs to:
Aaron Valencia
6828 A Street
Tacoma,Washington 98408
(206)849-0204
Maintenance Requirements
The stormwater management facilities provided in Attachment A include provisions for
inspection procedures and maintenance, when necessary. All stormwater facilities that
were designed for are accounted for. Maintenance procedures for additional components
are also provided, which consist of general practices for some of the selected drainage
features for this development. Only applicable facilities and components per the
stormwater design are required to be inspected and maintained.
A
ATTACHMENT A
No.2—Infiltration
Maintenance Defect Conditions When Maintenance Is Results Expected When
Component Needed Maintenance Is
Performed
General Trash&Debris See"Detention Ponds"(No. 1). See"Detention Ponds"
(No. 1).
Poisonous/Noxious See"Detention Ponds"(No. 1). See"Detention Ponds"
Vegetation (No.1).
Contaminants and See"Detention Ponds"(No. 1). See"Detention Ponds"
Pollution (No. 1).
Rodent Holes See"Detention Ponds"(No. 1). See"Detention Ponds"
(No. 1)
Storage Area Sediment Water ponding in infiltration pond after Sediment is removed
rainfall ceases and appropriate time and/or facility is cleaned
allowed for infiltration.Treatment basins so that infiltration system
should infiltrate Water Quality Design Storm works according to
Volume within 48 hours,and empty within design.
24 hours after cessation of most rain
events.
(A percolation test pit or test of facility
indicates facility is only working at 90%of
its designed capabilities.Test every 2 to 5
years.If two inches or more sediment is
present,remove).
Filter Bags(if Filled with Sediment and debris fill bag more than 1/2 Filter bag is replaced or
applicable) Sediment and full. system is redesigned.
Debris
Rock Filters Sediment and By visual inspection,little or no water flows Gravel in rock filter is
Debris through filter during heavy rain storms. replaced.
Side Slopes of Erosion See"Detention Ponds"(No. 1). See"Detention Ponds"
Pond (No. 1).
Emergency Tree Growth See"Detention Ponds"(No.1). See"Detention Ponds"
Overflow Spillway (No.1).
and Berms over 4
feet in height.
Piping See"Detention Ponds"(No. 1). See"Detention Ponds"
(No. 1).
Emergency Rock Missing See"Detention Ponds"(No.1). See"Detention Ponds"
Overflow Spillway (No. 1).
Erosion See"Detention Ponds"(No. 1). See"Detention Ponds"
(No.I)-
Pre-settling Facility or sump 6"or designed sediment trap depth of Sediment is removed.
Ponds and Vaults filled with Sediment sediment.
and/or debris
No. 10-Filter Strips
Maintenance Defect or Condition When Recommended Maintenance to Correct
Component Problem Maintenance is Needed Problem
General Sediment Sediment depth exceeds 2 Remove sediment deposits,re-level so
Accumulation on inches. slope is even and flows pass evenly through
Grass strip.
Vegetation When the grass becomes Mow grass,control nuisance vegetation,
excessively tall(greater such that flow not impeded.Grass should be
than 10-inches);when mowed to a height between 3-4 inches.
nuisance weeds and other
vegetation starts to take
over.
Trash and Debris Trash and debris Remove trash and Debris from filter.
Accumulation accumulated on the filter
strip.
Erosion/Scouring Eroded or scoured areas For ruts or bare areas less than 12 inches
due to flow channelization, wide,repair the damaged area by filling with
or higher flows. crushed gravel.The grass will creep in over
the rock in time.If bare areas are large,
generally greater than 12 inches wide,the
filter strip should be re-graded and re-
seeded.For smaller bare areas,overseed
when bare spots are evident_
Flow spreader Flow spreader uneven or Level the spreader and clean so that flows
clogged so that flows are are spread evenly over entire filter width.
not uniformly distributed
through entire filter width.
a
RECEIVED
NOV 3 0 2020
Drainage Report 615 W. Alder Street
Valencia Single Family Residential Property
4361 E State Route 302, Belfair
Parcel No. 12221-43-00100
Mason County, Washington
November 10, 2020
Project#20169
Prepared For:
Aaron Valencia
6828 A Street
Tacoma, Washington 98408
Phone: 206-849-0204
Prepared By:
Envirotech Engineering
PO Box 984
Belfair, Washington 98528
Phone: 360-275-9374
EL CCYDr S
'2
1
a3 s
11/10/20
l �
TABLE OF CONTENTS
1.0 PROJECT DESCRIPTION.................................................................................................................. 1
2.0 EXISTING CONDITIONS...................................................................................................................2
2.1 TOPOGRAPHY......................................................................................................................................2
2.2 SURFACE DRAINAGE...........................................................................................................................2
2.3 SUBSURFACE CONDITIONS................................................. ............................2
.....................................
2.3.1 SUBSURFACE CONDITIONS..............................................................................................................2
2.3.2 GROUNDWATER...............................................................................................................................3
3.0 HYDROLOGIC/HYDRAULIC INFORMATION............................................................................3
3.1 DEVELOPED SITE DRAINAGE CONDITIONS........................................................................................3
3.2 DOWNSTREAM ANALYSIS...................................................................................................................4
3.2.1 TRIBUTARY DRAINAGE AREA.........................................................................................................4
3.2.2 DOWNSTREAM DISCHARGE.............................................................................................................4
3.2.3 DOWNSTREAM EROSION AND WATER QUALITY............................................................................4
3.2.4 DOWNSTREAM CONCLUSIONS.........................................................................................................4
3.3 HYDROLOGY AND HYDRAULIC ANALYSIS/DESIGN..........................................................................4
3.4 ROOF DOWNSPOUT INFILTRATION....................................................................................................4
3.5 FILTER STRIP......................................................................................................................................5
4.0 INSPECTION AND MAINTENANCE................................................................................................6
4.1 INSPECTION AND MAINTENANCE SCHEDULE.....................................................................................6
4.2 INSPECTION AND MAINTENANCE RESPONSniILm...........................................................................6
5.0 CONTROL OF POLLUTANTS OTHER THAN SEDIMENTS.......................................................S
6.0 PROJECT ENGINEER'S CERTIFICATION....................................................................................9
Appendices
Appendix A—Site Map
Appendix B—Pollution Source BMP
4
1.0 PROJECT DESCRIPTION
Envirotech Engineering (Envirotech) has completed this drainage report in conjunction with the
stormwater management plan for Valencia Single Family Residence located at 4361 E State
Route 302 (Parcel 1222143-00100) in Mason County, Washington. See the Vicinity Map below
for a general indication of the Project location.
Information pertaining to the development of this project was provided by the proponent of the
property. The proposed development includes a Single Family Residence, driveway, on-site
septic system,and associated stormwater management facilities.
It is anticipated that the roof area will encompass 2500 sf in size, and road/ driveways will
encompass approximately 8350 sf in size for a total of 10850 sf proposed impervious surface
area. The total land area that is anticipated to be disturbed as a result of development is 1.45
acres.Cut and fill quantities were approximated to be 12 cubic yards(cy)and 12 cy,respectively.
See the accompanying stormwater management plans for an illustration of current and proposed
site features.
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Vicinity Map from Mason County Website
Envirotech Engineering Drainage Report
PO Box 984 page 1 Parcel 12221-43-00100
Belfair, Washington 98528 Mason County,Washington
Ph. 360-275-9374 November 10,2020
2.0 EXISTING CONDITIONS
The property is accessed from E State Route 302, an existing paved highway in unincorporated
Mason County. The Project is currently undeveloped, with some clearing on-site. Vegetation is
typical of the Pacific Northwest.
E State Route 302 extends in a north-south direction to the west of the property. Beyond the
property,rural residential development exists.
2.1 Topography
Descending slopes exceeding 15%are located on and beyond the property. Average slope grades
are approximately 20%with a vertical relief of approximately 120 feet.
2.2 Surface Drainage
The natural drainage from the property is directed to the west end of the property. The water
travels by sheet flow to a county drainage ditch located to the west of the property. The drainage
ditch appears to infiltrate into the existing subsurface.
2.3 Subsurface Conditions
Information on infiltration rates and soil conditions pertaining to the Project was accomplished by
Envirotech. Selected information pertaining to the drainage aspect of the project is provided
below.
The following subsurface conditions are estimated descriptions of the Project subgrade utilizing
information from the depth of penetration at all testing, sampling, observed and investigated
locations. Soils for this project were described utilizing the Unified Soil Classification System
(USCS). Using the USCS in conjunction with estimated relative densities and other anticipated
engineering properties of the soil, susceptibility for potential landslides, erosion and seismic
hazards may be assessed.
2.3.1 Subsurface Conditions
The project is primarily composed of undisturbed, native soils, without indications of
substantial fill. Competent bearing soils were encountered at 12 inches below the existing
native ground surface in locations where the ground was probed. For engineering
purposes,these native soils consist of distinguishable layers,as presented below.
Soils within the upper 4 feet of natural ground were observed to be primarily moist,
brown silty sand with gravel and some clay (SM). Expanded and specific subsurface
descriptions, other than what is provided in this section, are provided in the geological
assessment under a separate cover.
According to the "Soil Survey of Mason County," by the United States Department of
Agriculture, Soil Conservation Service (SCS), the site soils are described as Alderwood
Envirotech Engineering Drainage Report
PO Box 984 page 2 Parcel 12221-43-00100
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 November 10,2020
gravelly sandy loam,Ab,with 8%- 15% slopes and Everett very gravelly sandy loam, Eh
and Ek,with 8%-30%slopes. See the soil map below.
Based on the fines content,erodibility of the site soils is considered to be medium. Based
on the fines content and fraction of clay within the fines content, settleability of the site
soils is expected to be fast. Permeability is expected to be moderate for this site due
significance of moderate density,and fine-grained soils.
2.3.2 Groundwater
From the water well report(s)and knowledge of the general area,permanent groundwater
is at least 100 feet below the current ground surface. Surface seepage or perched
groundwater at shallow depths was not observed on-site, nor indicated on the well
reports. However, some seasonal groundwater is expected to flow directly above the
hardpan on occasion.
pop
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Aerial/Soils Map from USDA NRCS Website
3.0 HYDROLOGIC/HYDRAULIC INFORMATION
3.1 Developed Site Drainage Conditions
It is anticipated that the access road/ driveways will encompass approximately 3550 sf in size as
the total proposed impervious surface area. The total land area that is anticipated to be disturbed
as a result of development is 1.45 acres. Cut and fill quantities were approximated to be 12 cubic
yards (cy) and 12 cy, respectively. Best Management Practices (BMPs) for this project includes
an infiltration bed, and bio-swales. Natural drainage patterns are to be maintained to the
maximum extents practicable.
Envirotech Engineering Drainage Report
PO Box 984 page 3 Parcel 1222143-00100
Belfair,Washington 98528 Mason County, Washington
Ph. 360-275-9374 November 10,2020
3.2 Downstream Analysis
This project has been analyzed as a Level 1 Downstream Drainage Analysis in accordance with
the prevailing Western Washington Stormwater Drainage Manual.
3.2.1 Tributary Drainage Area
The upslope watershed is located within the parcel,and flows to both the southeast and
west of the property.There is a drainage basin located to the east property line,labeled as
a DNR water course.The project is not expected to impact the stream,and is located
beyond the fish and wildlife setback.
3.2.2 Downstream Discharge
The natural drainage from the site appears to be directed to Case Inlet, located 200 ft to
the west of the project.
3.2.3 Downstream Erosion and Water Quality
FEMA mapping, and other documentation do not reveal flooding or erosion hazards on
the property.
Water quality within the project watershed is not known to have major issues. Ordinary
pollution caused by residences and roadways are pollution contributors in the area.
Off-site mitigation is not deemed necessary for this Project. This is based on the scale of
the proposed Project,and on-site mitigation design.
3.2.4 Downstream Conclusions
The project will increase pollution generating surfaces by 8350 sf. Existing mild sloping
green areas appear to have sufficient vegetation and pollution removal qualities for the
pollution generating surfaces.
The proposed drainage design encourages sheet flow dispersal for the runoff. It is our
opinion that with proper maintenance and care of the proposed drainage facility, the
proposed development will not constitute measurable runoff to offsite properties.
3.3 Hydrology and Hydraulic Analysis/Design
BMP T5.10A was used to design all stormwater facilities for this project. Per the soils
analysis,through visual inspection,the rooftop infiltration shall have a minimum of 75
lineal ft trench per 1000 sf of impervious area.
3.4 Roof Downspout Infiltration
Storm water runoff from the roof of all structurers will be directed to its own separate infiltration
Envirotech Engineering Drainage Report
PO Box 984 page 4 Parcel 12221-43-00100
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 November 10,2020
facility.
Based on BMP T5.10A,the infiltration trench was designed to the following parameters:
• 38 feet in length
• 10 feet bottom width
• 2 feet in depth
3.5 Filter Strip
It has been determined that a narrow area vegetative filter strip is the proposed BMP for this site.
A Narrow Area Vegetative Filter Strip(VFS)is a BMP's that uses areas of dense planted
vegetation(typically grass)and a flat cross slope to maintain sheet flow and remove sediment and
other pollutants from runoff coming directly off pavements or other pollution generating surface.
VFS is designed to treat an area of 1350 sf. Flow will enter as sheet flow and will not exceed a
depth of 1". The proposed narrow area VFS has a contributing flow path of 10 feet to the east of
the driveway, and 10 feet to the south of the driveway. The longitudinal slope of the driveway
contributing drainage area will be graded at no more than 5%. The lateral slope of the
contributing drainage area perpendicular to the driveway edge will be graded at 2%or less.
According to LID Design Guidance the design procedure is based on the Narrow Area Filter
Strips presented in the 2012 Western Washington Stowmwater Design Manual. The filter strip is
sized using the width of the flow-path and the longitudinal slope of the filter strip itself(parallel
to the flow-path). Since filter strips only provide basic treatment, they should be used where the
roadway ADT is less than 30,000 sf(in our project 2682 sf of total driveway area).
20.0
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Flowpath
30 feet
l o.o
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Filter Strip Slope
Envirotech Engineering Drainage Report
PO Box 984 page 5 Parcel 1222143-00100
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 November 10,2020
4.0 INSPECTION AND MAINTENANCE
Erosion and sediment control measures that may be necessary for this project includes:
• Temporary stabilized construction entrance;
• Temporary silt fence;and,
• Permanent vegetation.
The following subsections provide details regarding inspection and maintenance schedule,
inspection and maintenance responsibility,and an engineer's inspection report.
Stabilized Construction Entrance
The stabilized construction entrance shall be inspected at reasonable increments. Increased usage
of the construction entrance warrants more frequent inspections. Additional rock shall be added
periodically to maintain proper function of the pad.
Silt Fence
All silt fencing shall be inspected immediately after each rainfall and at least daily during
prolonged rainfall. Any required repairs shall be made immediately.
Permanent Vegetation
Permanent vegetation shall initially be inspected regularly to insure establishment and healthy
growth. Once established, vegetation may need to be periodically fertilized for continuous
growth.Vegetation shall be re-established in areas, if necessary.
4.1 Inspection and Maintenance Schedule
While active construction is in process, all temporary erosion and sediment control facilities shall
be inspected and immediately maintained if necessary per the requirements provided above. In
the event that construction activities are discontinued for at least 4 consecutive days, the owner
shall be responsible for the inspection, and immediate maintenance if necessary, of all temporary
erosion and sediment control facilities immediately after storm events, and at least once every 7
days.
In addition to the aforementioned inspection and maintenance schedule, the owner shall install
additional erosion and sediment control facilities if proposed erosion and sediment control
measures prove to be inadequate.
For permanent facilities, an Operation and Maintenance Manual should be required for this
project.
4.2 Inspection and Maintenance Responsibility
Inspection, maintenance, and financial liability of all temporary/ permanent erosion and
sedimentation control facilities shall ultimately be the responsibility of the property owner.
Envirotech Engineering Drainage Report
PO Box 984 page 6 Parcel 1222143-00100
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 November 10,2020
Currently,the property owner is:
Aaron Valencia
6828 A Street
Tacoma,Washington 98408
(206)849-0204
An operation and maintenance covenant will be required to cover all stormwater facilities.
Performance bonding, or other appropriate instrument, shall be required for this project to ensure
compliance with the standards presented in this report.
Furthermore, the owner may need to retain an Erosion and Spill Control (ESC) Lead for
construction observation and oversight of the project if required by the County to ensure
compliance with the ESC components of the approved Drainage and Erosion/ Sediment Control
Plans.
Envirotech Engineering Drainage Report
PO Box 984 page 7 Parcel 12221-43-00100
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 November 10,2020
5.0 CONTROL OF POLLUTANTS OTHER THAN SEDHAENTS
Upon completion of this project and future development of the lot, this project is expected to
render no more than 70 trips per day of traffic. Potential source of pollutants may occur from
spills, leaks, excessive usage, ordinary usage, or vandalism of several pollutants including the
following:
• Fuel
• Oil
• Solvent
• Degreaser
• Dust
• Pesticide
• Herbacide
• Fertilizer
• Other Chemicals
The aforementioned pollutants are not expected to be currently on-site.The potential sources may
be released into the stormwater due to development of the facilities, and/or future use of the
facilities.
Control of pollutants other than sediments include the following:
• All pollutants other than sediments shall be handled and disposed of in a manner
that does not cause contamination of stormwater.
• Cover, containment and protection from vandalism shall be provided for all
chemicals, liquid products, petroleum products, and non-inert wastes present on the
project site.
• Maintenance and repair of heavy equipment and vehicles involving oil changes,
hydraulic system drain down, solvent and de-greasing cleaning operations, fuel tank
drain down and removal, and other activities which may result in discharge or
spillage of pollutants to the ground or into stormwater runoff must be conducted
using spill prevention measures, such as drip pans. Contaminated surfaces shall be
cleaned immediately following any discharge or spill incident. Emergency repairs
may be performed on-site using temporary plastic placed beneath and, if raining,over
the vehicle.
• Wheel wash or tire bath wastewater shall be discharged to a separate on-site
treatment system or to the sanitary sewer, if available.
• Application of agricultural chemicals including fertilizers and pesticides shall be
conducted in a manner, and at application rates that will not result in loss of chemical
to stormwater runoff. Manufacturers' recommendations for application rates and
procedures shall be followed.
See the Best Management Practices for this development that should be adhered to after
construction is complete.
Envirotech Engineering Drainage Report
PO Box 984 page 8 Parcel 12221-43-00100
Belfair, Washington 98528 Mason County,Washington
Ph. 360-275-9374 November 10,2020
6.0 PROJECT ENGINEER'S CERTIFICATION
I hereby state that this drainage plan for the Valencia Single Family Residence has been prepared
by me or under my supervision and meets the standard of care and expertise which is usual and
customary in this community for professional engineers.
Please contact Michael Staten at 360-275-9374 if you have any questions, comments, or require
additional information.
Sincerely,
Envirotech Engineering
PtiL CLYDE Sr
SIt�
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43045
k<QSTCRE�
ssic),vALF"t' 11/10/20
Michael Staten,P.E.
Project Director
Envirotech Engineering Drainage Report
PO Box 984 page 9 Parcel 1222143-00100
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 November 10,2020
APPENDIX A
SITE MAP
COVER SHEET;EXISTING/PROPOSED CONDITIONS
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APPENDIX B
POLLUTION SOURCE BMP
BMPs for Description of Pollutant Sources: Landscaping can include grading, soil
Landscaping transfer, vegetation removal, pesticide and fertilizer applications, and
and Lawn/ watering. Stormwater contaminants include toxic organic compounds,
Vegetation heavy metals,oils, total suspended solids,coliform bacteria, fertilizers,and
Management pesticides.
Lawn and vegetation management can include control of objectionable
weeds, insects, mold, bacteria and other pests with chemical pesticides and
is conducted commercially at commercial, industrial,and residential sites.
Examples include weed control on golf course lawns, access roads, and
utility corridors and during landscaping; sap stain and insect control on
lumber and logs;rooftop moss removal,killing nuisance rodents;
fungicide application to patio decks, and residential lawn/plant care.
Toxic pesticides such as pentachlorophenol,carbamates, and
organometallics can be released to the environment by leaching and
dripping from treated parts,container leaks, product misuse,and outside
storage of pesticide contaminated materials and equipment. Poor
management of the vegetation and poor application of pesticides or
fertilizers can cause appreciable stormwater contamination.
Pollutant Control Approach: Control of fertilizer and pesticide
applications,soil erosion, and site debris to prevent contamination of
stormwater.
Develop and implement an Integrated Pest Management Plan (IPM)and
use pesticides only as a last resort. If pesticides/herbicides are used they
must be carefully applied in accordance with label instructions on U.S.
Environmental Protection Agency(CPA)registered materials. Maintain
appropriate vegetation,with proper fertilizer application where
practicable,to control erosion and the discharge of stormwater pollutants.
Where practicable grow plant species appropriate for the site, or adjust the
soil properties of the subject site to grow desired plant species.
;lpplicable Operational BJ11's for Landscaping:
• Install engineered soil/landscape systems to improve the infiltration
and regulation of stormwater in landscaped areas.
• Do not dispose of collected vegetation into waterways or storm
drainage systems.
Recommended Additional Operational BMPs for Landscaping:
• Conduct mulch-mowing whenever practicable
• Dispose of grass clippings, leaves, sticks,or other collected vegetation,
by composting, if feasible.
• Use mulch or other erosion control measures when soils are exposed
for more than one week during the dry season or two days during the
rainy season.
• If oil or other chemicals are handled, store and maintain appropriate oil
and chemical spill cleanup materials in readily accessible locations.
Ensure that employees are familiar with proper spill cleanup
procedures.
• Till fertilizers into the soil rather than dumping or broadcasting onto
the surface. Determine the proper fertilizer application for the types of
soil and vegetation encountered.
• Till a topsoil mix or composted organic material into the soil to create
a well-mixed transition layer that encourages deeper toot systems and
drought-resistant plants.
• Use manual and/or mechanical methods of vegetation removal rather
than applying herbicides, where practical.
Applicable Operational BMPs for the Use of Pesticides:
• Develop and implement an IPM(See section on IPM at end of BMP)
and use pesticides only as a last resort.
• Implement a pesticide-use plan and include at a minimum: a list of
selected pesticides and their specific uses;brands, formulations,
application methods and quantities to be used; equipment use and
maintenance procedures; safety,storage,and disposal methods; and
monitoring, record keeping, and public notice procedures. All
procedures shall conform to the requirements of Chapter 17.21 RCW
and Chapter 16-228 WAC(Appendix IV-D R.7).
• Choose the least toxic pesticide available that is capable of reducing
the infestation to acceptable levels. The pesticide should readily
degrade in the environment and/or have properties that strongly bind it
to the soil. Any pest control used should be conducted at the life stage
when the pest is most vulnerable. For example, if it is necessary to use
a Bacillus thurin iens is application to control tent caterpillars, it must
be applied before the caterpillars cocoon or it will be ineffective. Any
method used should be site-specific and not used wholesale over a
wide area.
• Apply the pesticide according to label directions. Under no conditions
shall pesticides be applied in quantities that exceed manufacturer's
instructions.
• Mix the pesticides and clean the application equipment in an area
where accidental spills will not enter surface or ground waters, and
will not contaminate the soil.
• Store pesticides in enclosed areas or in covered impervious
containment. Ensure that pesticide contaminated stormwater or
spills/leaks of pesticides are not discharged to storm drains. Do not
hose down the paved areas to a storm drain or conveyance ditch. Store
and maintain appropriate spill cleanup materials in a location known to
all near the storage area.
• Clean up any spilled pesticides and ensure that the pesticide
contaminated waste materials are kept in designated covered and
contained areas.
• The pesticide application equipment must be capable of immediate
shutoff in the event of an emergency.
• Do not spray pesticides within 100 feet of open waters including
wetlands,ponds, and streams, sloughs and any drainage ditch or
channel that leads to open water except when approved by Ecology or
the local jurisdiction. All sensitive areas including wells, creeks and
wetlands must be flagged prior to spraying.
• As required by the local government or by Ecology,complete public
posting of the area to be sprayed prior to the application.
• Spray applications should only be conducted during weather
conditions as specified in the label direction and applicable local and
state regulations. Do not apply during rain or immediately before
expected rain.
Recommended Additional Operational BMPs for the use of pesticides:
• Consider alternatives to the use of pesticides such as covering or
harvesting weeds, substitute vegetative growth, and manual weed
control/moss removal.
• Consider the use of soil amendments,such as compost, that are known
to control some common diseases in plants, such as Pythium root rot,
ashy stem blight, and parasitic nematodes. The following are three
possible mechanisms for disease control by compost addition(USEPA
Publication 530-F-9-044):
1. Successful competition for nutrients by antibiotic production;
2. Successful predation against pathogens by beneficial
microorganism; and
3. Activation of disease-resistant genes in plants by composts.
Installing an aiiieiided soil/landvcape st�vieni can preserve both the plant
si•.vtent and the soil syste»i more effec tiveh. This tine of approach
provides a soil/landscape systeni ivith adequate depth, permeahility, and
organic inatter to sustain itself and continue woi*ing as an effective
stornn ater infiltration s steni and a sustainable nutrient cvc•le.
• Once a pesticide is applied, its effectiveness should be evaluated for
possible improvement. Records should be kept showing the
applicability and inapplicability of the pesticides considered.
• An annual evaluation procedure should be developed including a
review of the effectiveness of pesticide applications,impact on buffers
and sensitive areas(including potable wells), public concerns, and
recent toxicological information on pesticides used/proposed for use.
If individual or public potable wells are located in the proximity of
commercial pesticide applications contact the regional Ecology
hydrogeologist to determine if additional pesticide application control
measures are necessary.
• Rinseate from equipment cleaning and/or triple-rinsing of pesticide
containers should be used as product or recycled into product.
• The application equipment used should be capable of immediate
shutoff in the event of an emergency.
For more information,rmation, contact the lf'SU Ertensio n Home-Assist Program.
(253)445-4556, or Bio-Integral Resource Center(BIRO, P.O. Box 7414.
Bei*eln,, CA.94707, or the ib trshington Departinent of Ecology to Obtain
"Hazardous Waste Pesticides"(Publication /"-89-41);and/or CPA to
obtain a publication entitled "Suspended. Canceled and Restricted
Pesticides"irhic•h lists all restricted pesticides and the spec•frc•trses that
are allowed Valuable information fiam thesesourres may also be
available On the internet.
Applicable Operational BMPs for Vegetation Management:
• Use at least an eight-inch "topsoil" layer with at least S percent organic
matter to provide a sufficient vegetation-growing medium. Amending
existing landscapes and turf systems by increasing the percent organic
matter and depth of topsoil can substantially improve the permeability
of the soil, the disease and drought resistance of the vegetation, and
reduce fertilizer demand. This reduces the demand for fertilizers,
herbicides, and pesticides. Organic matter is the least water-soluble
form of nutrients that can be added to the soil. Composted organic
matter generally releases only between 2 and 10 percent of its total
nitrogen annually,and this release corresponds closely to the plant
growth cycle. If natural plant debris and mulch are returned to the
soil,this system can continue recycling nutrients indefinitely.
• Select the appropriate turfgrass mixture for your climate and soil type.
Certain tall fescues and rye grasses resist insect attack because the
symbiotic endophytic fungi found naturally in their tissues repel or kill
common leaf and stem-eating lawn insects. They do not, however,
repel root-feeding lawn pests such as Crane Fly larvae, and are toxic to
ruminants such as cattle and sheep. The fungus causes no known
adverse effects to the host plant or to humans. Endophytic grasses are
commercially available and can be used in areas such as parks or golf
courses where grazing does not occur. The local Cooperative
Extension office can offer advice on which types of grass are best
suited to the area and soil type.
• Use the following seeding and planting BMPs, or equivalent BMPs to
obtain information on grass mixtures,temporary and permanent
seeding procedures,maintenance of a recently planted area, and
fertilizer application rates: Temporary Seeding, Mulching and Matting,
Clear Plastic Covering, Permanent Seeding and Planting, and Sodding
as described in Volume I1).
• Selection of desired plant species can be made by adjusting the soil
properties of the subject site. For example,a constructed wetland can
be designed to resist the invasion of reed canary grass by layering
specific strata of organic matters(e.g.,compost forest product
residuals)and creating a mildly acidic pH and carbon-rich soil
medium. Consult a soil restoration specialist for site-specific
conditions.
• Aerate lawns regularly in areas of heavy use where the soil tends to
become compacted. Aeration should be conducted while the grasses
in the lawn are growing most vigorously. Remove layers of thatch
greater than'/4-inch deep.
• Mowing is a stress-creating activity for turfgrass. When grass is
mowed too short its productivity is decreased and there is less growth
of roots and rhizomes. The turf becomes less tolerant of
environmental stresses, more disease prone and more reliant on outside
means such as pesticides, fertilizers and irrigation to remain healthy.
Set the mowing height at the highest acceptable level and mow at
times and intervals designed to minimize stress on the turf. Generally
mowing only 1/3 of the grass blade height will prevent stressing the
turf.
Irrigation:
• The depth from which a plant normally extracts water depends on the
rooting depth of the plant. Appropriately irrigated lawn grasses
normally root in the top 6 to 12 inches of soil; lawns irrigated on a
daily basis often root only in the top 1 inch of soil. Improper irrigation
can encourage pest problems, leach nutrients,and make a lawn
completely dependent on artificial watering. The amount of water
applied depends on the nonnal rooting depth of the turfgrass species
used, the available water holding capacity of the soil,and the
efficiency of the irrigation system. Consult with the local water utility,
Conservation District,or Cooperative Extension office to help
determine optimum irrigation practices.
Fertilizer Alanagement.
• Turfgrass is most responsive to nitrogen fertilization, followed by
potassium and phosphorus. Fertilization needs vary by site depending
on plant,soil and climatic conditions. Evaluation of soil nutrient
levels through regular testing ensures the best possible efficiency and
economy of fertilization. For details on soils testing, contact the local
Conservation District or Cooperative Extension Service.
• Fertilizers should be applied in amounts appropriate for the target
vegetation and at the time of year that minimizes losses to surface and
ground waters. Do not fertilize during a drought or when the soil is
dry. Alternatively,do not apply fertilizers within three days prior to
predicted rainfall. The longer the period between fertilizer application
and either rainfall or irrigation, the less fertilizer runoff occurs.
• Use slow release fertilizers such as methylene urea,IDBU, or resin
coated fertilizers when appropriate, generally in the spring. Use of
slow release fertilizers is especially important in areas with sandy or
gravelly soils.
• Time the fertilizer application to periods of maximum plant uptake.
Generally fall and spring applications are recommended, although
WSU turf specialists recommend four fertilizer applications per year.
• Properly trained persons should apply all fertilizers. At commercial
and industrial facilities fertilizers should not be applied to grass
swales, filter strips,or buffer areas that drain to sensitive water bodies
unless approved by the local jurisdiction.
Integrated Pest�yanagement
An 1PM program might consist of the following steps:
Step 1: Correctly identify problem pests and understand their life cycle
Step 2: Establish tolerance thresholds for pests.
Step 3: Monitor to detect and prevent pest problems.
Step 4: Modify the maintenance program to promote healthy plants and
discourage pests.
Step 5: Use cultural,physical, mechanical,or biological controls first if
pests exceed the tolerance thresholds.
Step 6: Evaluate and record the effectiveness of the control and modify
maintenance practices to support lawn or landscape recovery and prevent
recurrence.
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r-- 12" CULVERT
SILT FENCE
ASPHALT ENTRANCE r
PROPOSED STRUCTURE
FF: 127.00, 2500 SQ. FT.
STABALIZED CONSTRUCTION
ENTRANCE GRAVEL DRIVEWAY 10'VEGETATED FILTER STRIP
(SEE DETAILS) APPROX. LOCATION
OF EXISTING WELL
CLEARING AREA
50 WELL
SE ACK 2 2089E
•, - . / 1 55
f� f� ••'• 4" SOLID PVC PIPE
L= 106.75, 5=4.2%
44
2 .
18% •'
/ 93
12 2066E 10
_a GOO
too 38' ON
v' LA ~ ~ BED (SEE DETAILS)
a,.
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100' WELL SETBACK
c+o
SILT FE
NCE PROPERTY LINE
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