21-101265-SU-Drainage Technical Information Report (TIR)-03-31-2021-V1DECCIO Engineering Inc.
17217 7th Avenue W.
Bothell, WA. 98012
(206) 390-8374
Fax: (425) 741-8214
Voda 2-Lot Short Plat
City of Federal Way #
Drainage Design Report,
O&M Manual & SWPP Report
Property Location:
35027 21st Avenue SW
Federal Way, WA
March 26, 2021
Prepared for:
Sazei Design Group
Deccio Engineering Inc Page i
TABLE OF CONTENTS
SECTION 1 PROJECT OVERVIEW 1
o Figure 1: TIR Worksheet 2
o Figure 2: Site Location Map 7
o Figure 3: Drainage Basins, Sub Basins and Site Characteristics 8
SECTION 2 CONDITIONS & REQUIREMENTS SUMMARY 9
❖ King County Requirements
SECTION 3 OFF-SITE ANALYSIS 13
❖ Sensitive Areas Map 13
❖ Drainage Complaint Map 13
o Figure 4: Upstream and Downstream Flow Map 15
o Figure 5: Downstream System Table 16
SECTION 4 FLOW CONTROL & WATER QUALITY ANALYSIS AND DESIGN 17
o Figure 6: Soils Map
o Figure 7: Developed Conditions Map
o Infiltration Requirements
o Soil Management Plan
SECTION 5 CONVEYANCE SYSTEM ANALYSIS AND DESIGN 17
SECTION 6 SPECIAL REPORTS AND STUDIES 22
SECTION 7 OTHER PERMITS 22
SECTION 8 SWPPP ANALYSIS AND DESIGN 23
SECTION 9 BONDS, SUMMARIES AND COVENANTS 24
SECTION 10 OPERATIONS AND MAINTENANCE MANUAL 30
❖ Operations and Maintenance Procedures
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SECTION 1 PROJECT OVERVIEW
Project:
Voda 2-Lot Short Plat
Site Information:
The proposed project is the construction of a 2-lot short plat project. The site is located on west
side of 23rd Ave SW in Federal Way, King County WA. (Parcel #242103-9072). The site
address is 35027 21st Avenue SW Federal Way, WA. See Figure 2: Vicinity Map. The site is
bordered by residential lots on the north, south, west sides of the site. The project will meet the
drainage requirements of the 2016 King County Stormwater Management Manual, as adopted by
the City of Federal Way.
Pre-developed Site Conditions:
The total site is 29,765 sf or 0.68 acres in size and will contain a total of two lots. The property
currently contains an existing home and garage which will remain. The site contains a few trees
and has a cover of landscaping. The site slopes from west to east, with slopes around 5% There
are no know sensitive areas on site Please refer to Figure 3: Existing Site Conditions..
Developed Site Conditions:
The site will be subdivided into two new lots. Lot 1 will contain the new home with driveway.
Lot 2 will contain the existing home and garage. The existing shed and carport will be removed.
Frontage improvements on 23rd Ave SW will consist of completion of the existing sidewalk.
Please refer to Figure 7: Developed Conditions Map
The following is a breakdown of proposed and existing impervious areas for each lot:
Lot 1 Impervious Area (New):
• Lot Area: 10,054 sf
• Roof/Covered Deck Area: 1,900 sf
• Driveway and Walkway: 848 sf
Total: 2,748 sf
• Right of way s-walk 200 sf
Total New Impervious Area: 2,948 sf
Lot 2 Impervious Area (Existing to Remain):
• Lot Area: 19,711 sf
• Exist Roof Area: 1,690 sf
• Exist Garage Area: 480 sf
• Driveway and Walkway: 5,508 sf
Total: 7,678 sf
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Figure 1: TIR Worksheet
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Figure 1: TIR Worksheet
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Figure 1: TIR Worksheet
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Figure 1: TIR Worksheet
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Figure 1: TIR Worksheet
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Figure 2: Site Location Map
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Figure 3: Existing Site Conditions
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SECTION 2 CONDITIONS & REQUIREMENTS SUMMARY
The King County 2016 Surface Water Design Manual governs the design of stormwater systems
to serve this project. The Core and Special Requirements are being met in the following manner:
King County Surface Water Design Manual Core Requirements:
1. Discharge at the Natural Location
Under 1.2.1-2, The surveyed contours show all runoff leaves the site towards the east. All
runoff will continue to flow east.
2. Off-site Analysis
The Level 1 downstream analysis showed that there will be minimal impacts on the
downstream conditions, since there was only one downstream complaint noted.
3. Flow Control
Since the total new impervious is under 5,000 sf, flow control is not required.
4. Conveyance System
There is no proposed conveyance pipes except for the 4” roof drain pipes.
5. Temporary Erosion & Sediment Control
All TESC measures proposed will conform to the 2016 KCSWDM during construction,
Refer to Section 9 of this TIR for additional information. The measures show on the
TESC plans include: Clearing limits, sediment control, soil stabilization, BMP’s
maintenance and construction sequence
6. Maintenance & Operations
Maintenance and Operations manual has been provided. Note that a “Declaration of
Covenant” may be required. See Section 10.
7. Financial Guarantees & Liability
A completed bond quantity worksheet will be provided.
8. Water Quality
Water quality is not required since the new PGHS area is under 5,000 sf
9. Flow Control BMP’s
The site was reviewed for on-site BMP’s which includes the use of dispersion trenches.
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Large Lot BMP Requirements: Section C.1.3.2
If the proposed project is on a site/lot that is 22,000 square feet or larger, but is not a Large
Rural Lot as defined in Section 1.3.3, THEN flow control BMPs must be applied as specified in
the requirements below OR the project must demonstrate compliance with the LID Performance
Standard (described in Core Requirement #9, Section 1.2.9 of the SWDM) using an approved
continuous runoff model.
1. The feasibility and applicability of full dispersion as detailed in Appendix C,
Section C.2.1 must be evaluated for all target impervious surfaces. If feasible
and applicable for any such surface, then full dispersion must be applied to that
surface and implemented as part of the proposed project. Typically, full
dispersion will be applicable only on the largest sites/lots where there may be
enough forest area available within a threshold discharge area to meet the 15%
ratio of fully dispersed impervious area to native vegetated surface.
• Full dispersion is not feasible since there are no native areas on-site.
2. Where full dispersion of target impervious roof areas is not feasible or
applicable, or will cause flooding or erosion impacts, the feasibility and
applicability of full infiltration of roof runoff must be evaluated in accordance
with Appendix C, Section C.2.2, or Section 5.2 of the SWDM, whichever is
applicable based on the type of project.11 If feasible and applicable, full
infiltration of roof runoff must be implemented as part of the proposed project.
• Is not proposed since the site soils are note suitable for infiltration
3. All target impervious surfaces not mitigated by Requirements 1 and 2 above,
must be mitigated to the maximum extent feasible using one or more BMPs
from the following list. Use of a given BMP is subject to evaluation of its
feasibility and applicability as detailed in Appendix C. Feasible BMPs are
required to be implemented. The BMPs listed below may be located anywhere
on the site/lot subject to the limitations and design specifications for each BMP.
These BMPs must be implemented as part of the proposed project.
• Full Infiltration per Appendix C, Section C.2.2, or per SWDM
Section 5.2, whichever is applicable
o Is not proposed since the soils are suitable for infiltration
• Limited Infiltration per Appendix C, Section C.2.3,
o Is not proposed since the site soils are not suitable for infiltration.
• Bioretention per Appendix C, Section C.2.6, sized as follows:
o Is not proposed since site soils are not suitable for
infiltration
o Inside the UGA (Rainfall region SeaTac 1.0 and less ): In till soils,
provide bioretention volume based on 0.6 inches of equivalent
storage depth; in outwash soils provide bioretention volume based
on 0.1 inches of equivalent storage depth
o Inside the UGA (Rainfall regions greater than SeaTac 1.0): In till
soils, provide bioretention volume based on 0.8 inches of
equivalent storage depth; in outwash soils, provide bioretention
volume based on 0.4 inches of equivalent storage depth,
o Outside the UGA: In till soils, provide bioretention volume
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based on 1.9 inches of equivalent storage depth; in outwash
soils provide bioretention volume based on 1.0 inches of
equivalent storage depth,
• Permeable Pavement per Appendix C, Section C.2.7,
Is not proposed since site soils are not suitable for infiltration.
4. All target impervious surfaces not mitigated by Requirements 1,2 and 3 above,
must be mitigated to the maximum extent feasible using the Basic Dispersion
BMP described below. Use of Basic Dispersion is subject to evaluation of its
feasibility and applicability as detailed in Appendix C. Feasible BMPs are
required to be implemented. Basic Dispersion BMPs may be located anywhere
on the site/lot subject the limitations and design specifications cited in Appendix
C. The BMP must be implemented as part of the proposed project.
• Basic Dispersion per Appendix C, Section C.2.4,
o The site will use dispersion trenches with 25-ft flow paths for basic
dispersion
5. BMPs must be implemented, at min for impervious area amounts defined as follows:
• Not Applicable, since the site will use basic dispersion
a) For projects that will result in an impervious surface coverage on the
buildable portion of the site/lot of less than 45%, flow control BMPs
must be applied to 50% of target impervious surfaces.
b) For projects that will result in an impervious surface coverage of 45% to
65% on the buildable portion of the site/lot, flow control BMPs must be
applied to 50% of target impervious surfaces reduced by 1.5% for each
1% of impervious surface coverage above 45% (e.g., impervious coverage
of 55% results in a requirement of FCBMPs applied to 35% of target
impervious surfaces).
c) For projects that will result in an impervious surface coverage greater than
65% on the buildable portion of the site/lot, flow control BMPs must be
applied to 20% of the target impervious surfaces or to an impervious area
equal to at least 10% of the site/lot, whichever is less.
The buildable portion of the site/lot is the total area of the site/lot minus any
critical areas and minus 200 ft. buffer areas from a steep slope hazard,
landslide hazard area, or erosion hazard area. If these minimum areas are not
mitigated using feasible BMPs from Requirements 1, 2, 3, and 4 above, either a
fee in lieu of the required minimum BMPs must be paid (requires that King
County Water and Land Resources Division has established a program for
determining and utilizing the fees for stormwater focused retrofit projects) OR
one or more BMPs from the following list are required to be implemented to
achieve compliance. These BMPs must be implemented as part of the proposed
project.
◼ Reduced Impervious Surface Credit per Appendix C, Section C.2.9,
• No reduction in impervious area is proposed since the site is
using dispersion.
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◼ Native Growth Retention Credit per Appendix C, Section C.2.10.
• There are no native growth areas on site to retain.
6. The soil moisture holding capacity of new pervious surfaces must be protected
in accordance with KCC 16.82.100 (F) and (G). KCC 16.82.100(F) requires
that the duff layer or native topsoil be retained to the maximum extent
practicable. KCC 16.82.100(G) requires soil amendment to mitigate for lost
moisture holding capacity where compaction or removal of some or all of the
duff layer or underlying topsoil has occurred. The specifications for compost
for soil amendment can be found in Reference 11-C.
• Compost amended soils will be used for the site.
7. Any proposed connection of roof downspouts to the drainage system must be
via a perforated pipe connection as detailed in Appendix C, Section C.2.11.
• Not applicable
Federal Way/King County Surface Water Design Manual Special
Requirements:
1. Other Adopted Area-Specific Requirements
There are no area-specific requirements for this project site.
2. Floodplain/Floodway Delineation
A review of the FEMA FIRM panels for the site, shows that the site and area of work is
outside any floodplain areas and site does not contain any floodplain/floodway
delineations.
3. Flood Protection Facilities
There are no flood protection facilities located on or directly adjacent to the site.
4. Source Control
This final site does not meet the threshold for source control requirements.
5. Oil Control
The site does not meet the “high use” criteria as defined under Section 1.3.5, Page 1-105
“SR#5 “Oil Control”
Federal Way Conditions
FINDINGS/CONCLUSIONS:
To be determined
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SECTION 3 OFF-SITE ANALYSIS
TASK 1 – STUDY AREA DEFINITIONS AND MAPS
Overview
This section of the TIR is a Level 1 Downstream Analysis per the 2016 King County Surface
Water Design Manual Sections 1.2.2.1 and 2.3.1.1 as required by the City of Federal Way.
The proposed project is the construction of a 2-lot short plat project. The site is located on the
west side of 23rd Avenue SW see Figure 2: Vicinity Map. The site is bordered by residential
lots on the north, east, and west sides of the site.
Upstream Drainage Analysis / Upstream Contributing Area
Based on the site contours, there is little to no off-site drainage from upstream areas draining
onto the site. The site itself slopes from west to east eliminating any off-site runoff from the
north and south sides of the site. Therefore, the drainage is limited to the site itself.
TASK 2 – RESOURCE REVIEW
Adopted Basin Plan
The site is located in the Dumas drainage basin.
Community Plan
None Known
Basin Reconnaissance Summary Report
We are not aware of a current Basin Reconnaissance Summary Report for this area.
Critical Drainage Area
The site is not considered to be within a critical drainage area as defined by the 2016 KCSWDM.
A review of the DOE “water quality assessment” web site shows that the site is not on the DOE
303(d) list.
Sensitive Area Maps
Per KC IMAP, the site does not contain any sensitive areas.
Soils Survey
A review of the USGS maps, show the site soils are a Type C and are not suitable for infiltration
Wetland / Stream Inventory
None on site
A review of the FEMA FIRM panels for the site, shows that the site and area of work is outside
any floodplain areas and site does not contain any floodplain/floodway delineations.
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Drainage Complaints
A review of the drainage complaints showed that there was one drainage complaint downstream
of the site which closed in 2001.
TASK 3 – FIELD INSPECTION
A Level 1 site inspection was performed on March 21, 2021. The weather was cool and cloudy.
The inspection focused on identifying potential downstream drainage and water quality problems
As previously indicated, the site slopes to the east with all runoff leaving along the east side of
the site
TASK 4 – DRAINAGE SYSTEM DESCRIPTION, AND PREDICTED DRAINAGE AND
WATER QUALITY PROBLEMS
OFFSITE LEVEL ONE DOWNSTREAM ANALYSIS
The runoff leaves the property along the east side and ties into the storm drainage system in 23rd
Avenue SW. From here the drainage flows north in 12” storm pipes and catch basins for over ¼
mile.
The total distance covered is just over ¼ mile
Basin 1 Predicted Drainage and Water Quality Problems
None Noted
TASK 5 MITIGATION OF EXISTING OR POTENTIAL PROBLEMS
Drainage BMP’s in the form of dispersion trenches are proposed to address the on-site runoff.
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Figure 4: Upstream Area and Downstream Flow Map
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Figure 5: Downstream System Table
Figure 6: Soils Map
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SECTION 4 FLOW CONTROL & WATER QUALITY
ANALYSIS AND DESIGN
The BMP’s where based on Section C.2 of Appendix C, the 2016 King County Surface Water
Design Manual (KCSWDM). Due to the site constraints, the project will use Basic Dispersion
for the roof areas and Basic dispersion for the driveways, and parking per Section C.1.3.2 for
large lots over 22,000 sf and Sections C.2.1 Full Dispersion and C.2.4 Basic Dispersion.
DRAINAGE MITIGATION BMP REVIEW
Since the lot is larger than 22,000 square feet, it is subject to the Large Lot BMP
Requirements in Appendix C of the Surface Water Design Manual. As mandated by these
requirements, all proposed “on-site” new impervious surfaces (2,948 square feet) is
targeted for application of flow control BMPs. As for the new pervious surface (totaling
2,948 square feet), it is less than 50% of the site, therefore, no flow control BMPs are
required for this surface.
To address the requirements for mitigation of the target impervious surface, the
applicability and feasibility of the following BMPs was considered:
• Full Dispersion: Not Feasible, since the site cannot meet the 100 foot flow paths for the
downspouts or dispersal trenches. Based on the site contours, the site can’t meet the
required flow paths prior to discharge from the site and therefore do not meet Section
C.2.1.1-3 a)
• Full Infiltration: Not Feasible, since the site soils are not suitable for infiltration. Therefore,
the soils do not meet separation required under section C.2.2.2-1-b)
• Limited Infiltration: Not Feasible, since the site soils are not suitable for infiltration
• Basic Dispersion: Will use a combination dispersion trench with 25-foot flow paths for
the roof areas and driveway dispersion with 10-ft flow paths.
• Post Construction Soil Standards: Will be used for all disturbed pervious areas
Therefore, based on the review of the above BMP’s, basic dispersion is the best suited for the
site.
Roof Dispersion Trench Sizing:
Trench Length = (1,900 sf / 700 sf per lf of trench) x 10-lf = 27.2 lf of trench (use 30 lf
of trench)
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Figure 6: Developed Site Conditions
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ENTIRE SITE
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Amend Existing Soils, Purpose and Definition
Naturally occurring (undisturbed) soil and vegetation provide important stormwater functions including: water
infiltration; nutrient, sediment, and pollutant adsorption; sediment and pollutant biofiltration; water interflow storage
and transmission; and pollutant decomposition. These functions are largely lost when development strips away
native soil and vegetation and replaces
it with minimal topsoil and sod. Not only are these important stormwater functions lost, but such landscapes
themselves become pollution- generating pervious surfaces due to increased use of pesticides, fertilizers and other
landscaping and household/industrial chemicals, the
concentration of pet wastes, and pollutants that accompany roadside litter.
Establishing soil quality and depth regains greater stormwater functions in the post development landscape, provides
increased treatment of pollutants and sediments that result from development and habitation, and minimizes the need
for some landscaping chemicals, thus reducing pollution through prevention.
Applications and Limitations
Establishing a minimum soil quality and depth is not the same as preservation of naturally occurring soil and
vegetation. However, establishing a minimum soil quality and depth will provide improved on-site management of
stormwater flow and water quality.
Soil organic matter can be attained through numerous materials such as compost, composted woody material,
biosolids, and forest product residuals. It is important that the materials used to meet the soil quality and depth BMP
be appropriate and beneficial to the plant cover to be established. Likewise, it is important that imported topsoils
improve soil conditions and do not have an excessive percent of clay fines.
Design Guidelines
Soil retention. The duff layer and native topsoil should be retained in an undisturbed state to the
maximum extent practicable. In any areas requiring grading remove and
stockpile the duff layer and topsoil on site in a designated, controlled area, not adjacent to public resources
and critical areas, to be reapplied to other portions of the site where feasible.
Soil quality. All areas subject to clearing and grading that have not been covered by impervious surface,
incorporated into a drainage facility or engineered as structural fill or slope shall, at project completion,
demonstrate the following:
I. A topsoil layer with a minimum organic matter content of ten percent dry weight in planting beds,
and 5% organic matter content (based on a loss-on-ignition test) in turf areas, and a pH from 6.0
to 8.0 or matching the pH of the original undisturbed soil. The topsoil layer shall have a
minimum depth of eight inches except where tree roots limit the depth of incorporation of
amendments needed to meet the criteria. Subsoils below the topsoil layer should be scarified at
least 4 inches with some incorporation of the upper material to avoid stratified layers, where
feasible.
2. Planting beds must be mulched with 2 inches of organic material
3. Quality of compost and other materials used to meet the organic content
requirements:
a. The organic content for -pre-approved” amendment rates can be met only using compost that
meets the definition of -composted materials” in WAC I73-350-220. This code is available
online at: http://www.ecy.wa.gov/programs/swfa/facilities/350.html.
Compost used in bioretention areas should be stable, mature and derived from yard debris, wood waste, or other
organic materials that meet the intent of the organic soil amendment specification. Biosolids and manure
composts can be higher in bio-available phosphorus than compost derived from yard or plant waste and therefore
are not allowed in bioretention areas due to the possibility of exporting bio-available phosphorus in effluent.
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The compost must also have an organic matter content of 35% to 65%, and a carbon to nitrogen ratio below 25:I.
The carbon to nitrogen ratio may be as high as 35:I for plantings composed entirely of plants native to the Puget
Sound Lowlands region.
b. Calculated amendment rates may be met through use of composted materials as defined above; or
other organic materials amended to meet the carbon to nitrogen ratio requirements, and
meeting the contaminant standards of Grade A Compost.
The resulting soil should be conducive to the type of vegetation to be established.
Implementation Options: The soil quality design guidelines listed above can be met by using one of the
methods listed below.
I. Leave undisturbed native vegetation and soil, and protect from compaction during construction.
2. Amend disturbed soil according to the following procedures:
b. Scarify subsoil to a depth of one foot
c. In planting beds, place three inches of compost and till in to an eight-inch depth.
d. In turf areas, place two inches of compost and till in to an eight-inch depth.
e. Apply two to four inches of arborist wood chip, coarse bark mulch, or compost mulch to
planting beds after final planting.
Alternatively, disturbed soil can be amended on a site-customized manner so that it meets the soil quality
criteria set forth above, as determined by a licensed engineer, geologist, landscape architect, or other
person as approved by King County.
3. Stockpile existing topsoil during grading, and replace it prior to planting. Stockpiled topsoil must
be amended if needed to meet the organic matter and depth requirements by following the
procedures in method (2) above).
4. Import topsoil mix of sufficient organic content and depth to meet the organic matter and depth
requirements.
5. More than one method may be used on different portions of the same site. Soil that already meets the
depth and organic matter quality standards, and is not compacted, does not need to be
amended.
Maintenance
Soil quality and depth should be established toward the end of construction and once established,
should be protected from compaction, such as from large machinery use, and from erosion.
Soil should be planted and mulched after installation.
Plant debris or its equivalent should be left on the soil surface to replenish organic matter.
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SECTION 6 SPECIAL REPORTS AND STUDIES
None Required.
SECTION 7 OTHER PERMITS
Below is the list of anticipated permits required for this project. Other permits may be required
that are not mentioned below.
Water and Sewer permits
Building Permits
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SECTION 8 SCWPPP ANALYSIS AND DESIGN
For the purposes of this report, several standard erosion control procedures will be utilized by the
contractor to minimize the amount of erosion and sedimentation perpetuated by the construction
of the site. Furthermore, these techniques are proposed for the Construction Stormwater
Pollution Prevention Plan (SCWPPP) and should be reviewed and instituted by the onsite
contractor. Some of the measures include filter fabric fence, and standard ground cover
practices, A construction sequence will also be used to minimize the impacts of erosion due to
construction.
THE 12 ELEMENTS OF A CONSTRUCTION SWPPP
1. Preserve Vegetation/Mark Clearing Limits: The clearing limits are indicated on the plan
sheet. Furthermore, clearing and grading will be limited to only areas that need to be disturbed
for grading/construction of the road surface to preserve as much natural vegetation as possible.
Field marking the clearing limits shall be completed prior to clearing and grubbing activities.
BMP's: Preserve Natural Vegetation (VEG)
Field Marking Clearing Limits (CL)
2. Establish Construction Access: Access to the construction site shall be limited to the rock
construction entrance. The construction entrance shall be extended to provide access to the
construction vehicle/equipment staging and employee parking areas.
BMP's: Stabilized Construction Entrance (CE)
3. Control of Flow Rates: Storm water detention: No detention is proposed for the site since the
increase in volume is less minimal
4. Installation of Sediment Controls: Sediment control will be provided through a combination
of filtration through the surround on-site vegetation, filter fence, straw bails,
BMP's: Silt Fence (FF)
5. Soils Stabilization: Temporary and permanent soil stabilization will be provided. Temporary
stabilization will be provided through the application of straw and/or plastic sheeting to exposed,
worked earth. From October 1 until April 30, no exposed soil may remain exposed and
unworked for more than two days; after May 1, no exposed soil may remain exposed and
unworked for more than seven days.
BMP's: Plastic Sheeting,
6. Slope Protection: Slopes shall be protected from erosion through cover and prevention of
concentrated surface runoff flows.
BMP's: Plastic Sheeting,
7. Protection of Permanent Drain Inlets: Inlet protection will pe provided for all catch basins.
BMP’s: N/A
8. Stabilization of Channels and Outlets: All channel slopes shall be constructed and protected
against erosion in accordance with King County
BMP's: None required
9. Pollutant Control: Pollutants shall be controlled as described in the Potential Pollutants section
of this SWPPP.
10. Dewatering Control: De-watering: Interception of the water table is not expected to occur,
even if there is an increase in precipitation. However, should ground water flows be
encountered, the flows can be directed to on site native vegetation for cleanup.
BMP's: Native vegetation (As Required)
11. BMP Maintenance: All BMP's and SWPPP elements shall be inspected daily and maintained as
required.
12. Project Management: The project shall be managed in a cooperative effort by the project
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manager, contractor, engineer, and the county inspector. During the construction process, if
unforeseen issues arise that cannot be resolved on site, construction activity (other than SWPPP
maintenance) shall be halted and the county inspector and the project engineer are to be
contacted and informed of the situation. The Erosion Control Lead is TBD
SECTION 9 BONDS, SUMMARIES AND COVENANTS
The necessary summaries and covenants will be provided and signed by the owner as required by
the City.
A preliminary “Declaration of Covenant” has been prepared for the drainage at the end of this
section.
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SECTION 10 OPERATIONS AND MAINTENANCE MANUAL
Stormwater System Description
The stormwater system for the site is fairly basic and contains the following elements:
• Dispersion Trench
• Catch basins:
The stormwater runoff from the site improvements flows into the dispersion trench for dispersed
discharge.