HomeMy WebLinkAboutERC_Talbot_Hill_Substation_170123DEPARTMENT OF COMMUNITY
AND ECONOMIC DEVELOPMENT -------~entOil 0
ENVIRONMENTAL REVIEW COMMITTEE REPORT
ERC MEETING DATE:
Project Name:
Project Number:
Project Manager:
Owner:
Applicant/Contact:
Project Location:
Project Summary:
Exist. Bldg. Area SF:
Site Area:
STAFF
RECOMMENDATION:
January 23, 2017
Talbot Hill Substation Improvements
LUA16-000922, ECF, SA-H,
Angelea Weihs, Associate Planner
Puget Sound Energy, Inc.; PO Box 97034 M/S PSE-09N, Bellevue, WA 98009
Jeff McMeekin; PO Box 97034 M/S PSE-09N, Bellevue, WA 98009
2400 S Puget Drive
PSE is requesting Hearing Examiner Conditional Use Permit, Environmental (SEPA) Review,
and Site Plan Review for proposed Talbot Hill Substation improvements located at 2400 S
Puget Dr. (parcel numbers 2023059003 and 2023059066). The project site totals 50.4 acres
and is zoned Residential-8 (R-8). PSE is proposing to rebuild a portion of the Talbot Hill
Substation in order to replace aging equipment and provide more reliability for the
transmission lines connected to the substation. The existing control house will be
demolished and a new control house is proposed in its place. The existing 230kV substation
equipment inside the fence is proposed to be removed, including steel structures and
foundations. No additional transmission lines are proposed with the rebuild of this project.
A new storm drainage system is proposed within the fenced area and a detention pond will
be installed south of the southerly substation fence. The detention pond will involve an
excavation of more than 500 cubic yards, which triggers SEPA Review. The substation
footprint will remain unchanged. Additional driveway improvements are proposed to allow
larger vehicle access to the substation. The project site contains moderate coalmine
hazards, moderate landslide hazards, and sensitive slopes (within 50 feet). The applicant
has submitted an Arborist Report and Geotechnical Engineering Study with the application.
999 SF
50.4 acres
Proposed New Bldg. Area (footprint):
Proposed New Bldg. Area (gross):
Total Building Area GSF:
1,449 SF
1,449 SF
2,448 SF
Staff Recommends that the Environmental Review Committee issue a Determination of
Non-Significance -Mitigated (DNS-M).
Project Location Map
ERC Report_LUA16-000922 Talbot Hill Substation
City of Renton Department of Community & Economic Development
Report Talbot Hill Substation Improvements
Report of January 23, 2017
PART ONE: PROJECT DESCRIPTION / BACKGROUND
Environmental Review Committee
LUA16-00D922, ECF, SA-H,
Page 2 of 6
PSE is requesting a Hearing Examiner Conditional Use Permit, Environmental (SEPA) Review, and Site Plan Review for
proposed Talbot Hill Substation improvements located at 2400 S Puget Dr. (parcel numbers 2023059003 and
2023059066). The project site totals 50.4 acres and is zoned Residential-8 (R-8). PSE is proposing to rebuild a portion
of the Talbot Hill Substation in order to replace aging equipment and provide more reliability for the transmission
lines connected to the substation. The substation footprint will remain unchanged. The subject proposal is being
reviewed independently and separately from all other proposals, including Energize Eastside (the proposal to build
new electrical transmission infrastructure), that include this site.
The Talbot Hill Substation was constructed in the early 1960s and is a legally established use. A Conditional Use
Permit was not required at the time of construction; however, due to the upgrades of the facility (enlargement of
control house) a new Conditional Use Permit has been triggered. The existing control house (999 square feet) would
be demolished and a new control house (1,449 square feet) would be constructed in its place. The proposed new
control house exceeds the maximum height for accessory structures within the R-8 zone (total 18 feet to highest
point) by 1 foot and 4 inches, and therefore requires approval of a Hearing Examiner Conditional Use Permit. The
existing 230kV substation equipment inside the fence is proposed to be removed, including steel structures and
foundations. The new equipment will be reconfigured to create a more efficient and more reliable substation and
allow for flexible functioning of the system. The proposal includes some transmission line work outside the
substation fence; however, no additional transmission lines are proposed with the rebuild of this project. A new
storm drainage system will be constructed within the fenced area and a detention pond will be installed south of the
southerly substation fence. The total disturbed area will equal approximately 227,370 square feet. The cut will be
approximately 11,500 cubic yards and the fill will be approximately 9,000 cubic yards. The storm improvements
would require the removal of 69 trees. The applicant proposes to remove 11 significant (Douglas fir) trees to the
west of the entrance driveway (outside of the proposed drainage pond) along the south side of the substation.
Additional driveway improvements are proposed to allow larger vehicle access to the substation. The project site
contains moderate coalmine hazards, moderate landslide hazards, and sensitive slopes (within 50 feet). The
applicant has submitted an Arborist Report and Geotechnical Engineering Study with the application.
PART TWO: ENVIRONMENTAL REVIEW
In compliance with RCW 43.21C.240, the following environmental (SEPA) review addresses only those project
impacts that are not adequately addressed under existing development standards and environmental regulations.
A, Environmental Threshold Recommendation
Based on analysis of probable impacts from the proposal, staff recommends that the Responsible Officials:
Issue a DNS-M with a 14-day Appeal Period,
B. Mitigation Measures
1. The applicant shall submit a revised Geotechnical report, updated to the 2015 IBC design parameters,
with construction and building permit application, and the project shall follow the recommendations of
the revised Geotechnical report.
C. Exhibits
Exhibit 1
Exhibit 2
ERC Report
Neighborhood Detail Map
ERC Report_LUA15-000922 Talbot Hill Substation
City of.Renton Department of Community & Economic Development
Report Talbot Hill Substation Improvements
Report of January 23, 2017
Site Plan
Tree Removal and Landscape Plan
Access Road and Grading Plan
Environmental Review Committee
LUA16-000922, ECf, SA-H,
Page 3 of6
Exhibit 3
Exhibit 4
Exhibit 5
Exhibit 6
Exhibit 7
Exhibit 8
Exhibit 9
Exhibit 10
Geotechnical Engineering Study prepared by GeoEngineers, Inc. (December 5, 2016)
Technical Information Report prepared by HDR Engineering, Inc. (November 16, 2016)
Arborist Report prepared by Tree Solutions Inc. (dated May 12, 2015)
Construction Mitigation Description
Advisory Notes to Applicant
D. Environmental Impacts
The Proposal was circulated and reviewed by vorious City Departments and Divisions ta determine whether the
applicant has adequately identified and addressed environmental impacts anticipated to occur in conjunction
with the proposed development. Staff reviewers have identified that the proposal is likely to have the following
probable impacts:
1. Earth
Impacts: A geotechnical report (Exhibit 6), dated December 5, 2016, completed by Geo Engineers, Inc. was
submitted with the application. The project site contains moderate coalmine hazards, moderate landslide
hazards and sensitive slopes (within 50 feet). Erosion control measures would need to be in place prior to
starting grading activities on the site. The report discusses the soil and groundwater characteristics of the
site including infiltration potential and provides recommendations for project design and construction. The
report discounts the use of infiltration for the site due to the depth of the outwash soils compared to the
existing surface elevations present on the site. Geotechnical recommendations presented would need to be
addressed within the project plans and construction/building permit submittal.
According to the report, the soils mapped in the project vicinity are predominantly glacial till, but include
localized areas of ice-contact glacial deposits overlying the till. The extent of disturbance will be
approximately 5.89 acres. The cut will be approximately 11,500 cubic yards and the fill will be approximately
9,000 cubic yards. Approximately 4.17 acres will consist of gravel road and surface improvements. Another
1.22 acres will be for the installation of new foundations and Spill Prevention, Control, and
Countermeasures (SPCC) structures. The remaining 0.5 acres will be for installation of a storm water
detention pond.
The report states that the site is mapped in a moderate coal mine hazard area; however, based on the depth
of historical coal mining activity and the relatively shallow depth of the proposed improvements, there is a
low coal mine hazard at the site. The report identifies that the site is mapped in a 25 to 40 percent steep
slope area and in a moderate landslide hazard area; however, the geotechnical engineer has concluded that
the proposed improvements would not adversely affect the stability of the slopes in or around the site.
Based on the provided report, the soils underlying the substation site have a low risk of liquefying under the
design earthquake event and a low risk of lateral spread and earthquake-induced slope movement. The site
is approximately 5 miles south of the Seattle Fault Zone, which is thought to have a recurrence interval on
the order of 1,000 years. Based on the distance from the nearest mapped fault, there is a low risk of fault
rupture at the site.
GeoEngineers understand that the stormwater pond is planned with 2H:1V (horizontal:vertical) side slopes
and a depth of up to 7 feet in the middle. They recommend that the side slopes be protected from erosion.
fRC Report_LUA16-000922 Talbot Hill Substation
City of Renton Department of Community & Economic Development
Report Talbot Hill Substation Improvements
Report of January 23, 2017
Environmental Review Committee
LUAlG-000922, ECF, SA-H,
Page 4 of 6
Temporary erosion protection should be used and maintained in areas with exposed or disturbed soils to
help reduce the potential for erosion and reduce transport of sediment to adjacent areas and receiving
waters. Temporary erosion protection should include the construction of a silt fence around the perimeter
of the work area prior to the commencement of grading activities. Permanent erosion protection should be
provided by re-establishing vegetation or surfacing with rock. Until the permanent erosion protection is
established and the site is stabilized, site monitoring should be performed by qualified personnel to evaluate
the effectiveness of the erosion control measures and repair and/or modify them as appropriate. Provisions
for modifications to the erosion control system based on monitoring observations should be included in the
erosion and sedimentation control plan, which shall be submitted to the City with the Construction Permit
application.
The Geotechnical report should be updated to 2015 IBC design parameters, as the current study was not
compliant. The geotechnical report includes specific recommendations for: site preparation, shallow and
mat foundations, drilled shafts, retaining walls, earthwork, temporary slopes, erosion and sedimentation
control, and the stormwater pond. Therefore, staff recommends, as a mitigation measure, that a revised
Geotechnical report, updated to the 2015 IBC design parameters, shall be submitted with construction
permit application and the project shall follow the recommendations of the revised Geotechnical report.
Mitigation Measures: The applicant shall submit a revised Geotechnical report, updated to the 2015 IBC
design parameters, with construction permit application and the project shall follow the recommendations
of the revised Geotechnical report.
Nexus: SEPA Environmental Review, RMC 4-3-050 Critical Areas Regulations and RMC 4-4-060 Grading,
Excavation and Mining Regulations
2. Air
Impacts: It is anticipated that some temporary air quality impacts could be associated with site work and
building construction required to develop this site. Project development impacts during construction may
include dust, resulting from grading and exhaust from construction vehicles. Dust control would be
mitigated through the use of watering of the site as needed.
No further site specific mitigation for the identified impacts from typical vehicle and construction exhaust is
required.
Mitigation Measures: No further mitigation recommended.
Nexus: N/A
3. Water
a. Storm Water
Impacts: A Preliminary Drainage Plan and Technical Information Report (TIR) (Exhibit 7), dated November
16, 2016, was submitted by HDR Engineering, Inc. with the Land Use Application. Based on the City of
Renton's flow control map, the site falls within the Flow Control Duration Standard area matching Forested
Site Conditions and is within the Lower Cedar River and Black River Drainage Basin. The development is
subject to Full Drainage Review in accordance with the 2009 King County Surface Water Design Manual
(KCSWDM) and the 2010 City of Renton Amendments to the KCSWDM. All core requirements and the six
special requirements are discussed in the Technical Information Report.
As stated in the TIR, the proposed improvements would occur on the eastern side of the substation
(referred to as the project area), and would include the installation of foundations, security perimeter fence,
landscape screening, paving of a small portion of the access road, installation of a new stormwater drainage
and flow control system, road maintenance, and on-site oil spill control best management practices (BMPs).
The extent of disturbance will be approximately 5.89 acres. Approximately 4.17 acres will consist of gravel
road and surface improvements. Another 1.22 acres will be for the installation of new foundations and Spill
Prevention, Control, and Countermeasures (SPCC) structures. The remaining 0.5 acres will be for installation
ERC Repon_LUA16-000922 Talbot Hill Substation
City of Renton Department of Community & Economic Development
Report Talbot Hill Substation Improvements
Report of January 23, 2017
Environmental Review Committee
LUA16-000922, ECF, SA-H,
Page 5 of 6
of a stormwater detention pond. The existing site contains electrical structures, and yard rock covers the
ground surface.
In general storm water runoff flows outwards from the middle of the substation. Existing drainage pipes on
the northeast and southeast sides of the substation are tied to catch basins within the fence line whose rims
are slightly raised above the yard rock, preventing them from capturing flow. The perimeter path on the
northeastern side of the substation is higher than the existing grade within the fence line, preventing flow
from draining off the site along this edge. An elevated field along the eastern edge of the site prevents
drainage away from the substation on this side. Runoff along the northeastern, eastern, and southeastern
sides of the substation therefore tends to pond within the substation and infiltrate. Along the southern edge
of the substation, runoff is able to flow south across the southern perimeter path and into a depression
located between the substation and access road. This route presents the path of least resistance for
storm water. The depression is drained by a culvert beneath the access road to a second depression which
drains eastwards, towards Grant Avenue South.
Proposed conditions would include a re-graded gravel surface within the substation (approximately 3.43
acres), additional SPCC structures and equipment foundations (approximately 1.22 acres), re-grading of
gravel and asphalt roads (approximately 0.74 acres), and the addition of a pond for flow control
(approximately 0.5 acres). The proposed conditions would increase impervious area at the site by
approximately 15%. This percentage is primarily due to the addition of the SPCC structures and equipment
foundations, as well as asphalt entries to the gravel access driveways. Yard rock surfaces would only be
replaced or re-graded, they would not be added.
Drainage improvements include a new storm water conveyance network inside the substation which would
route flows to a 75,000 cubic foot stormwater detention pond located along the southeastern edge of the
substation. This pond would discharge to a depression on the southern side of the existing access road,
where flow would resume the existing drainage path towards Grant Avenue South.
As noted in the report, the applicant is exempt from water quality since the new plus replaced pollution
generating impervious surface (PGIS) area is less than 5,000 square feet. Any changes to the redevelopment
project which results in greater than 5,000 square feet of PGIS area, as defined by the 2009 KCSWDM, may
trigger water quality facilities to be provided.
Mitigation Measures: No further mitigation recommended.
Nexus: N/A
4. Vegetation
Impacts: An Arborist Report prepared by Otak Inc., dated December 13, 2016 (Exhibit 8), was submitted
with the Land Use application, in addition to a Stormwater Pond Tree Removal and Landscaping Plan (Exhibit
4). A total of 116 trees were evaluated as a part of this proposal. The existing trees on the project site
include Douglas firs, Pacific dogwood, Big leaf maple, Madrone, Alder, Willow, Hawthorn, Beaked Hazelnut,
and Cottonwood. Per the arborist report, the majority of the trees are in good shape with the exception of
the willow and alder, which have been damaged by recent branch failures during the spring windstorms. The
Arborist Report states that the grading of the stormwater pond would require removal of significant trees. A
total of 69 trees are proposed for removal within the stormwater pond area per the submitted tree removal
plan. The applicant proposes to remove 11 significant (Douglas fir) trees to the west of the entrance
driveway (outside of the proposed drainage pond) along the south side of the substation. The report states
that the majority of these trees are reaching a height in which their risk toward the substation is enhanced
due to the prevalence of windblown limbs damaging equipment within the substation. The existing shrubs
and smaller trees in this area are proposed to remain as a view buffer for the southern neighbors. No
alternatives to tree removal for the 11 Douglas firs was provided within the Arborist Report, nor did the
report provide explanation for why the Douglas fir trees could not be trimmed as a solution to prevent
damage to the equipment within the substation, rather than tree removal. Therefore, staff will be
ERC Report_LUA16-000922 Ta/bat Hill Substation
City of Renton Department of Community & Economic Development
Report Talbot Hill Substation Improvements
Report of January 23, 2017
Environmental Review Committee
LUA!G-000922, ECF, SA-H,
Page 6 of 6
recommending a condition of Site Plan approval to address these concerns prior to construction permit
approval.
Mitigation Measures: No further mitigation recommended.
Nexus: N/A
E. Comments of Reviewing Departments
The proposal has been circulated to City Department and Division Reviewers. Where applicable, their
comments have been incorporated into the text of this report and/or "Advisory Notes to Applicant."
./ Copies of all Review Comments are contained in the Official File and may be attached to this report.
The Environmental Determination decision will become final if the decision is not appealed within the 14-day
appeal period {RCW 43.21.C.075{3); WAC 197-11-680).
Environmental Determination Appeal Process: Appeals of the environmental determination must be filed in
writing together with the required fee to: Hearing Examiner, City of Renton, 1055 South Grady Way, Renton, WA
98057, on or before 5:00 p.m. on February 10, 2017. RMC 4-8-110 governs appeals to the Hearing Examiner and
additional information regarding the appeal process may be obtained from the City Clerk's Office, Renton City Hall -
7th Floor, (425) 430-6510.
ERC Report_LUA16-000922 Talbot Hill Substation
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