DrainageUtilitiesReport-July10-07-TracksAccepted
THURSTON HIGHLANDS
GRADING, DRAINAGE, AND UTLITY
TECHNICAL ENGINEERING REPORT
July 10, 2007 / Draft Grading, Drainage, and Utility
Technical Engineering Report
4200- 6th Avenue SE, Suite 309
Lacey, WA 98503
(360) 292-7230
(360) 292-7231 FAX
Draft Grading, Drainage, and Utility Technical Engineering Report
July 10, 2007
Prepared for:
Thurston Highlands, LLC
4200 Sixth Avenue SE, Suite 301
Lacey, WA 98503
Prepared by:
KPFF Consulting Engineers
4200 Sixth Avenue SE, Suite 309
Lacey, WA 98503
Table of Contents
SECTION PAGE
1.0 PROJECT OVERVIEW #
1.1 Pre-Developed Conditions #
1.2 Proposed Development #
Preferred Alternative #
Traditional Development Alternative #
Urban Village Alternative #
No-action Alternative #
1.3 Phased Development #
2.0 CLEARING AND GRADING PROPOSAL #
2.1 Existing Conditions #
2.2 Proposed Developed Conditions #
2.3 Design Requirements #
2.4 Project Impacts #
Potential Construction Impacts #
Earthwork around Kettles #
On-Site Gravel Processing #
Stockpiling #
Potential Operational Impacts #
2.5 Mitigation Measures #
Incorporated Plan Features #
Applicable Regulations and Commitments #
Other Recommended Mitigation Measures #
2.6 Phased Development #
3.0
4.0
5.0 SEWER #
5.1 Existing Conditions #
5.2 Proposed Developed Conditions #
Master-Plan Proposal #
5.2.1 Preferred Alternative #
5.2.2 Traditional Development Alternative #
5.2.3 Urban Village Alternative #
5.2.4 No-Action Alternative #
5.3 Design Requirements #
5.4 Project Impacts #
Potential Construction Impacts #
Potential Operational Impacts #
5.5 Mitigation Measures
Incorporated Plan Features #
Applicable Regulations and Commitments #
Other Recommended Mitigation Measures #
5.6 Phased Development #
6.0 RE-USERECLAIMED WATER #
6.1 Existing Conditions #
6.2 Proposed Developed Conditions #
6.3 Design Requirements #
6.4 Project Impacts #
Potential Construction Impacts #
6.5 Mitigation Measures #
Incorporated Plan Features #
Applicable Regulations and Commitments #
Other Recommended Mitigation Measures #
6.6 Phased Development #
7.0 ELECTRICAL POWER #
7.1 Existing Conditions #
7.2 Proposed Developed Conditions #
7.3 Design Requirements #
7.4 Project Impacts #
Potential Construction Impacts #
Potential Operational Impacts #
7.5 Mitigation Measures #
Incorporated Plan Features #
Applicable Regulations and Commitments #
Other Recommended Mitigation Measures #
7.6 Phased Development #
8.0 NATURAL GAS #
8.1 Existing Conditions #
8.2 Proposed Developed Conditions #
8.3 Design Requirements #
8.4 Project Impacts #
Potential Construction Impacts #
Potential Operational Impacts #
8.5 Mitigation Measures #
Incorporated Plan Features #
Applicable Regulations and Commitments #
Other Recommended Mitigation Measures #
8.6 Phased Development #
9.0 TELECOMMUNICATIONS #
9.1 Existing Conditions #
9.2 Proposed Developed Conditions #
9.3 Design Requirements #
9.4 Project Impacts #
Potential Construction Impacts #
Potential Operational Impacts #
9.5 Mitigation Measures #
Incorporated Plan Features #
Applicable Regulations and Commitments #
Other Recommended Mitigation Measures #
9.6 Phased Development #
List of Figures
1.1- Vicinity Map #
1.2- Existing Site Conditions #
1.3- Proposed Phase 1 Development #
1.4- Existing Site Conditions #
1.5- Preferred Alternative Conceptual Land Use Plan #
A.2 Development Alternative Conceptual Land Use Plan #
A.3 Urban Village Conceptual Land Use Plan #
3.1 Soil Logs and Soil Infiltration #
List of Tables
2.2-1 Estimated developed condition total impervious area #
2.4-1 Estimated required volume for infiltration facilities #
2.4-2 Estimated required volume for water quality – wet pond facilities #
4.3-1 Water system requirements of the Preferred Alternative #
4.3-2 Water system requirements of the Traditional Development Alternative #
4.3-3 Water system requirements of the Urban Village Alternative #
Appendices
Appendix A Master Plan Exhibits #
A.1 Hybrid Master Plan #
A.2 Traditional Master Plan #
A.3 Urban Village Master Plan++ #
Appendix B NRCS Soil Map and Information #
Appendix C Site Drainage Basin Map #
Appendix D City of Yelm, Staff Report from Sept. 19, 2006 “Principles of Sustainable Development #
Appendix E WWHM Drainage Calculations #
Appendix F DOE Approved BMP’s #
Appendix G Tahoma Boulevard Cross-Section #
Appendix H Preliminary Sewer Loading Calculations #
Appendix I Preliminary Re-UseReclaimed Water Calculations #
1.0 PROJECT OVERVIEW
[Mark: This is called Project Overview in the Table of Contents. Please revise section headings and numbering to be consistent with the TOC, or vice versa.]
This report documents existing site conditions and provides analysis and objectives of the proposed clearing and grading proposal, stormwater management and utility infrastructure options
for the Thurston Highlands Master Planned Community. Included in this report are calculations and analysis of projected impacts associated with three conceptual land use alternatives
and the No Action Alternative, with discussion of proposed and other possible mitigation measures.
The 1,240-acre site of the Thurston Highlands Master Planned Community is located between SR 507, SR 510 and Fort Lewis to the west. The site is a portion of the land that was annexed
to the City of Yelm in July 1994 as part of the Southwest Yelm Annexation. It is the same property that in 2004 was considered for the site of a NASCAR track (see Figure 1).
The City of Yelm annexed the property during the same time period that it adopted its Growth Management Act (GMA) Comprehensive Plan. The site has been zoned for a Master Planned Community
since its annexation and the adoption of the Comprehensive Plan, with the expectation that it would develop with a mix of urban residential, neighborhood commercial, public facilities,
open space and recreational amenities.
Pre-Developed Conditions
The subject site was a former Weyerhaeuser tree farm with the marketable timber harvested approximately 18 years ago. Today, most of the land supports replanted, even-aged stands of
rather monotypic Douglas fir trees, varying in age from 5 to 25 years. The only existing utility on the site is the Centralia Utilities aerial power lines that cross the western half
of the property. Wetlands in the northeast corner of the project site form the headwaters of Thompson Creek. Underlying till soils present throughout the project site sustain several
wetlands, many of which occur in isolated kettles (see Figure 2).
[Please review technical reports prepared by others (e.g., Steve Shanewise, Bill Parnell) for consistent description of existing site conditions.]
Figure 1.1 Vicinity Map
Figure 1.2 Existing Site Conditions
Proposed Development
Thurston Highlands, L.L.C. has submitted a Conceptual Master Site Plan proposal for the Thurston Highlands property. For the purpose of developing a Preferred Alternative, the applicant
considered a range of development densities that would meet the objectives of the proposal. Four conceptual land use alternatives are being evaluated in the Thurston Highlands EIS. Master
Plan exhibits in Appendix "A" show conceptual land use plans for three development alternatives. The fourth alternative is No Action.
Although each of the three development alternatives has a different allocation of uses, any of the “build” alternatives would include:
Residential Neighborhoods with a mix of single-family detached homes, single-family attached dwelling units, and multi-family dwelling units
Commercial areas, including a possible Village Square as a focal point
Parks, recreational facilities, open space and trails
Wetlands and wildlife habitat areas to be preserved
Schools and other possible public service sites
Utility and stormwater infrastructure, including water, sewer, reclaimed water, and franchise utilities
Preferred Alternative
The Preferred Alternative is a development scenario for approximately 5,000 dwelling units to be provided in a mix of housing types and densities; approximately 825,000 square feet (sf)
of retail commercial development; approximately 135,000 sf of office space; approximately 400 acres of permanent open space; a Regional Sports Complex; school sites and onsite provisions
for other public services and utilities (e.g., water supply, wastewater collection and treatment, stormwater management facilities, electrical power and communications; transit facilities;
churches; and a possible fire station); and extension of Tahoma Boulevard through the site to SR 507.
The Preferred Alternative blends characteristics of traditional development and an urban village concept, described below as the range of land use alternatives. The size and configuration
of the Thurston Highlands site are well-suited to the creation of multiple development patterns within a single project. The conceptual plan envisions that the eastern portion of the
property (nearest to the City center) may be appropriate for an urban village development pattern, while the western portion may be appropriate for more traditional development (see
Figure x in Appendix A, Preferred Alternative: Conceptual Land Use Plan). The Preferred Alternative is projected to generate a resident population of approximately 12,548 persons over
the 10- to 30-year build-out of the project.
Traditional Development Alternative
The Traditional Development Alternative would be characterized by a suburban development pattern consisting of a curvi-linear, gridded street system with an emphasis on single-family
residential neighborhoods and small-scale neighborhood convenience commercial uses located throughout the Master Planned Community (see Figure x in Appendix A, Traditional Development
Alternative: Conceptual Land Use Plan). A larger portion of the site would be allocated to single-family detached homes. Residential neighborhoods in this alternative would spread the
residential density out over the majority of the project site, providing larger lot sizes (5,000 to 7,000 square feet) and an average density of 4 dwelling units per buildable acre.
This development pattern would be consistent with the type of residential development that has occurred in Yelm over the past several years. The projected resident population of the
Traditional Development Alternative is approximately 13,859 persons over the 10 to 30 year build-out of the project. Non-residential uses under this alternative could include approximately
480,000 sf of retail commercial development, and approximately 150,000 sf of office use. With the lower-density, more spread-out development pattern under this alternative, it is likely
that only about 25 percent of the site (approximately 315 acres) would be preserved in open space. All other aspects of the Master Planned Community (Regional Sports Complex, school
sites, on-site provisions for other public services and utilities, and extension of the boulevard) would be similar to those described for the Preferred Alternative.
Urban Village Alternative
The Urban Village concept would create compact areas of high-density residential uses inter-mixed with commercial uses around a central Village Square (see Figure x in Appendix A, Urban
Village Alternative: Conceptual Land Use Plan). The predominant land use would be townhomes, apartments, and condominiums oriented around a neighborhood focal point, like a park, plaza
or school. The total estimated resident population of the Urban Village Alternative at full build-out would be approximately 10,998 persons.
Neighborhoods would have much smaller single-family lots, with an average density ranging from 5 to 7 dwelling units per buildable acre. Private yards would generally be smaller, though
some areas of the site would still be developed as traditional single-family residential subdivisions, likely in the northeastern portion of the community adjacent to Tahoma Terra, continuing
that land use pattern into Thurston Highlands before transitioning to higher-density development.
As with the Preferred Alternative, the Village Square would be the focal point of commercial development and open space. Approximately 850,000 sf of retail commercial development could
be provided in the Urban Village Alternative, and approximately 650,000 sf of office development. With the concentration of development near the interior of the site, a larger
amount of open space could be preserved around the perimeter ( on the order of 400 to 500 acres (30 to 40 percent of the site).
No Action Alternative
If the Thurston Highlands Master Planned Community did not proceed, there would be no need for the site preparation and utilities infrastructure described in this report until another
development proposal was submitted at some future time. Based on the site zoning and Comprehensive Plan designation, it is presumed that the site would remain vacant and undeveloped
until a Master Planned Community could be successfully implemented.
Phased Development
The applicant proposes to build-out the Thurston Highlands Master Planned Community over a period of 10 to 30 years in response to market demand, and in response to the availability
of public services and infrastructure required to accommodate this growth in the community. At this rate, 250 to 400 residential units per year would be built and made available for
occupancy. Full build-out is expected to be complete in the timeframe between 2018 and 2038.
To assist public service providers with planning for early stages of development within Thurston Highlands, a Phase 1 development concept is described, illustrated, and evaluated in
this report. Phase 1 would consist of approximately 1,008 homes (single-family detached and multi-family) to be constructed between approximately 2008 and 2011, and to be occupied between
approximately 2009 and 2012. Phase 1 development would occur in the northeast corner of the site, extending into Thurston Highlands from Tahoma Terra (see Figure __). These new homes
would likely be entirely within the Yelm Community Schools district, and would require the construction of one new elementary school.
Future phases beyond Phase 1 had not been conceptualized at the time of this writing.
Figure 1.3 Proposed Phase 1 Development
2.0 CLEARING AND GRADING PROPOSAL
This section describes potential earthwork, clearing and grading operations that would occur on site to support the development and will identify impacts and address alternatives to
mitigate those impacts for the following items:
General earthwork activities to create suitable building/residential pads.
On-site rock processing to create road-building material, utility trench backfill and building pads.
Clearing and grading in and around sensitive areas.
Existing Conditions
The existing 1,240-acre site has variable topography and landscape, shaped by the repeated advance and retreat of continental glaciers. Site topography is generally rolling in nature,
with average grades ranging from approximately 5 to 15 percent. Maximum grades are on the order of 0 percent to more than 40 percent in a few areas (see Figure __). Aerial topographic
surveys of the area indicate that elevations range from a high of 560 feet in the northwest corner to a low of 340 feet along the eastern property line. The westerly half of the proposed
project area contains several “kettle” depressions, formed when blocks of ice buried in glacial moraines melted. Some of these kettles occur in impervious soils and support wetlands,
and some occur in porous soils and are well-drained.
A total of 35 individual wetland systems have been delineated on the Thurston Highlands property. Most of these occur in the southern half of the site. Many are small, isolated systems
with no outlet. The largest wetland complexes occur in the southeast and northeast quadrants of the property. These systems represent the headwater beginnings to drainage routes that
eventually connect to the off-property, Thompson Creek channel approximately 0.5 mile to the east. Only a single, short segment of a Type F stream (approximately 200 feet), connecting
two wetlands, occurs within the entire project area emphasizing the depressional topography prevalent throughout the landscape. Wetland systems, along with their functions and values,
are described in a separate technical report prepared for the project (Coot Company, June 2007A).
Existing vegetative cover is remnant from a former Weyerhaeuser clear-cut forestry operation. Most of the land is covered by replanted, dense stands of even-aged, nearly monotypic Douglas
fir trees, varying in age from 5 to 25 years. Some meadows on the site have very few trees and consist mainly of grasses and invasive shrubs.
Figure 1.4 Existing Site Conditions
2.2 Proposed Developed Conditions
To complete development of an urban-density Master Planned Community consistent with City of Yelm zoning and Comprehensive Plan designations of the site, significant clearing of vegetation
and grading would be required in all areas not designated as sensitive areas, protected habitat, or permanent open space. It can be expected that approximately 100 to 300 acres of land
will be cleared and graded at any given time for development purposes. As each of these areas is stabilized with either permanent or temporary methods, and in response to market demand,
another 100 to 300 acres would be cleared.
Stormwater management facilities will be created in areas with reasonable infiltration capacity, including some existing kettles. These facilities will be constructed early in the
clearing process for use in the temporary erosion/sedimentation control system during site development. Fine sediments will be removed, and they will be converted to permanent stormwater
detention/infiltration facilities once the site is completely stabilized. The clearing and grading proposal would be essentially the same for site development under any of the three
conceptual land use alternatives.
Design Requirements
Clearing and grading activities will comply with applicable state and local regulations at the time of each phase of development. More restrictive measures may be identified in other
Thurston Highlands Master Planned Community technical reports, including:
Wildlife and Habitats Impact Assessment (Coot Company,
June 2007B).
Soils Evaluation Report (Insight Geologic, June 2007).
[Mark: We don’t have a “Soils Evaluation Report” from Bill Halbert. He has been asked to prepare a consolidated Geotechnical Report for the project, for which the earliest date of issue
will be June 2007. Please highlight the citations for technical reports being prepared by others to confirm dates and titles when final.]
Project Impacts
Construction-related impacts and mitigation measures would be similar for any of the conceptual land use alternatives. There would be no earthwork impacts if no development activity
took place under the No Action Alternative.
Potential Construction Impacts
To complete development of an urban-density master planned community consistent with City of Yelm zoning and Comprehensive Plan designations for this site, significant
clearing of vegetation and grading would be required in all areas not designated as sensitive areas, protected habitat, or permanent open space. Buffers for any protected area (including
slopes) would be established, and guidelines would be created for work that could occur in the buffers, subject to restoration and/or enhancement requirements. Slope instability and
erosion would be possible if clearing and grading occurred either on slopes, or close to the toe of slopes. Erosion from instabilities could contribute to sediment in wetlands and streams.
Some slopes may be completely lowered to match surrounding grades.
Although no formal site plan has been proposed at the time this report has been prepared, it should be anticipated that the majority of the areas not designated as protected would be
cleared, and topography would be altered to some degree. Table xx represents a range in areas that could be cleared and graded under the three conceptual land use alternatives.
Table 2.3.1. Clearing estimate for each conceptual land use alternative.
Conceptual Land Use
Alternative
Estimated Clearing
(in acres)
Percentage of the Site to be Cleared
Preferred Alternative
x,xxx – x,xxx ac
xx%
Traditional Development Alternative
x,xxx – x,xxx ac
xx%
Urban Village Alternative
x,xxx – x,xxx ac
xx%
A detailed description of habitat values in areas to be cleared is provided in the Wildlife and Habitats Impact Assessment prepared for the project (Coot Company, June 2007B).
[Mark (6/10/07 note): Please confirm Steve’s report title and date when issued in July.]
Earthwork around Kettles
Wetlands varying in classification and value have been identified in the kettle depressions that occur on the site (Coot Company, June 2007A). Alternative approaches are being considered
for how these kettles will be addressed in the grading proposal. These alternatives include:
Leave kettle wetland and associated buffer unaltered and develop around it while maintaining existing hydrology.
Leave kettle wetland unaltered, but clear and grade within allowable parameters of associated buffer as outlined by wetland biologist (Coot Company, June 2007A). Maintain existing hydrology.
Leave kettle wetland unaltered, but clear and grade within allowable parameters of associated buffer as outlined by wetland biologist (Coot Company, June 2007A). Hydrology may be altered
for low-value wetlands to use the kettle for stormwater infiltration purposes.
Fill kettle wetland and relocate existing hydrological function using other means of infiltration described in Section 3.0 of this report.
Some combination of these approaches to the kettle wetlands on the site is likely to occur. The proposal will be evaluated by City decision makers overall, and on a case-by-case basis
associated with specific plat applications for implementation of the Master Planned Community.
On-site Gravel Processing
Another earthwork impact would be excavation and grading in areas with suitable gravel material to be used for on-site construction material. The intent of this element of the proposal
is to utilize existing gravel material for road building, utility trench backfill, and/or building pad construction. The main area targeted for gravel processing is in the southeast
corner of the site, where commercial development is indicated on the conceptual land use plans. The estimated quantity of gravel available from this source is approximately xx cubic
yards (in-place material).
Grades will be altered, but hydrology should not be impacted significantly as areas targeted for gravel extraction are high points where runoff has high potential to infiltrate or surface-flow
to lower areas.
Noise associated with excavation, screening of the gravel to variable specification sizes, possible rock crushing, on-site hauling and distribution of material will be addressed in the
Environmental Impact Statement being prepared for the Thurston Highlands development. Types of machinery that may be used for these purposes may include excavators, bulldozers, wheeled
front-loaders; a portable screening plant, feed-hopper, portable gravel crusher, finishing crusher, water trucks, highway/off-road trucks for transport, and vibratory/sheep-foot compactor
rollers.
Stockpiling
Stumps, branches, topsoil and other material will need to be stockpiled on the site as clearing and grading activities take place. Stumps, branches and other vegetative material will
be stockpiled for possible wood chipping, saved for use in landscaping, or disposed offsite. Although it is difficult to asses with any certainty approximate quantities of material
given the varying conditions and quantities of trees throughout the site, it is likely that multiple stockpiles of wood debris approximately 30 feet high and 100 feet in diameter will
exist for each area cleared. Once the site is completely
cleared, the material will be chipped, or otherwise disposed offsite. Excavators, stump pullers, bulldozers and off-road trucks are possible machinery needed for this activity.
[Mark: By “once the site is completely cleared,” do you mean all 1,240 acres? This seems improbable, because it suggests that stockpiles would be moved from one phase to another, until
there was a cumulative total at the end. Do you mean instead, “As each phase of the development area is completely cleared. . .”]
Topsoil is another material expected to be stockpiled as clearing and grading activities occur. Once clearing and vegetation removal has occurred, it can be assumed that roughly 6 to
12-inches of topsoil material can be scrapped off the surface for future use. For each 1 acre cleared, approximately 800 to 1,600 cubic yards of topsoil will be scrapped from the site.
This material can be reused on-site in areas to be landscaped, or sold for use by others off-site. Topsoil stockpiles could be as large as 30 feet high and 60 feet in diameter. Land
scrappers, bulldozers and off-road trucks are the types of equipment that may be needed for this activity.
Potential Operational Impacts
There would be no clearing and grading in the developed condition of the Master Planned Community.
Mitigation Measures
Incorporated Plan Features
Mitigation measures for impacts to kettle wetlands and wetland buffers are described in a separate technical report prepared for the project (Coot Company, June 2007A).
Noise associated with gravel processing could be addressed by appropriate location and orientation of plant facilities away from sensitive areas and sensitive receivers. Temporary screens
could be erected around this equipment to minimize sound levels transmitted off-site. Consideration should also be given to the proximity of existing haul routes and batching plants
to sensitive areas and sensitive receivers. The existing haul roads on the site (former logging roads) will could be utilized until such time as appropriate permits are in-hand from
the U.S. Army Corps of Engineers and Washington Department of Ecology for wetland crossing and wetland buffer impacts that may occur at some locations associated with permanent road
construction.
The gravel source and on-site gravel processing capability would minimize the need for heavy-duty hauling vehicles to transport this construction material on local streets and state
highways for a prolonged period of time. Most construction vehicle traffic associated with road building would occur internal to the site.
Vegetation stockpiles will have a relatively low potential for erosion or wind spread particles, so these should be located out of the way of construction activity. Topsoil stockpiles
have a greater chance of erosion by wind or precipitation; therefore, they should be covered per standard Best Management Practices in addition to being located out of the way of disturbance,
and away from sensitive areas.
[Mark (5/20/07 note): When you arrive at the estimate of the quantity of material, you could estimate the number of truck trips that will occur on-site, that therefore will not need
to occur on public roads for the transport of construction material.]
Applicable Regulations and Commitments
All clearing and grading activities, including stockpiling, would be conducted in compliance with City of Yelm and Washington State regulations. Best Management Practices for erosion/sedimentation
control and construction stormwater management would be implemented consistent with the Ecology 2005 Stormwater Manual for Western Washington, or more current regulations at the time
of each phased development application. Water trucks would be on-site daily for dust control.
The applicant would be required to comply with applicable City of Yelm regulations for work within wetland buffers and steep slope buffers, unless more restrictive provisions for compliance
with City regulations are specified in the Development Agreement conceptual master site plan approvalfor the Master Planned Community.
Construction-related noise would be regulated by Washington Administrative Code (WAC) Chapter 173-60 Washington Administrative Code. Work hours would be limited to allowable hours provided
under state and local laws. Subject to some restrictions on the duration of maximum allowable noise levels, WAC Section 173.-60.-050 WAC exempts noise related to construction activity
between the hours of 7:00 AM to 10:00 PM.
Other Recommended Mitigation Measures
More thorough geotechnical evaluations would be performed to characterize subsurface conditions at the time of each phased development proposal to address erosion potential, slope stability,
soil creep and other potential earth impacts. All proposed development should be designed and constructed to prevent stormwater runoff from discharging onto slopes in a concentrated
manner.
Phased Development
The phased development proposal would result in preparing approximately 250 lots per year for new home construction. Approximately 100 acres of the site would be cleared for each 250-lot
subdivision application. As these lots are sold and construction is underway, the next (100 acres would be cleared for development. In this manner, only
approximately 100 acres would be cleared, undergoing development, and/or awaiting landscaping at any one time.
The Phase 1 development area encompasses a large wetland complex and habitat area to be protected. Under any conceptual land use alternative, this area of the site would be predominantly
residential, and would also include the Regional Sports Complex and some public service sites (e.g., schools). The existing topography of the Phase 1 development area is rolling with
little or no flat land suitable for building pads. Clearing and grading on the order of 500,000 cubic yards to 750,000 cubic yards of earthwork would be required in the Phase 1 development
area.
The Phase 1 proposal may include filling one or more small wetlands, and/or grading a portion of the buffer associated with small wetlands for overall compatibility with finished grades.
The Wetland Impact Analysis and Mitigation Recommendations document (Coot Company, June 2007A) describes wetland buffer restoration and/or enhancement, and compensatory mitigation for
wetland fill.
It is anticipated that gravel base for the roads and building pads will come from within the Thurston Highlands property, but outside the Phase 1 boundary. Existing haul roads (former
logging roads) would be used to transport material from the gravel extraction and processing area in the southeast portion of the site to the Phase 1 development area.
[Mark (5/07/07 note): Please confirm Steve’s report title and date when issued in July. Please add a paragraph re: the approach to the grading proposal for subsequent phases of development.]
SEWER
The City of Yelm hired the consulting firm of Parametrix, Inc. to prepare a Wastewater Technical Report to analyze the City’s existing sewage collection, treatment and disposal system,
and options for serving the Thurston Highlands Master Planned Community as well as other growth within the City’s Urban Growth Area (UGA). KPFF provided use data for the Thurston Highlands
portion of the analysis to estimate the wastewater collection and treatment requirements of the Master Planned Community, based on typical population estimates for the area consistent
with City standards. KPFF did not prepare calculations to assess Thurston Highlands sewer needs.
The final Yelm Wastewater Technical Report (Parametrix, Inc., March 2007) evaluates several alternatives and sub-alternatives as feasible strategies for collection, treatment and disposal
of additional wastewater loads that will be generated from development of Thurston Highlands. Two of these alternatives were evaluated in detail, selected as best able to meet the City’s
goals and objectives for producing Class A reclaimed water and minimizing additional surface discharge to the Nisqually River. KPFF was not involved in selecting or evaluating the alternatives,
or in formulating conclusions and recommendations made in the Parametrix report.
5.1 Existing Conditions
The Thurston Highlands site has no existing sewage collection or treatment infrastructure. The nearest infrastructure to the site is an 8-inch Septic Tank Effluent Pump (STEP) main located
in Tahoma Terra as part of Phase I Division 1 and 2 of that development, near the northeast boundary of Thurston Highlands. Additional infrastructure has been designed for construction
in Tahoma Boulevard through Phase II of Tahoma Terra, scheduled for construction in Summer 2007. The size of this line would be adequate to convey projected wastewater flows from Master
Planned Community development on the Thurston Highlands site.
The City’s existing wastewater collection, treatment, and disposal system is owned, operated and maintained by the City, and consists of a Septic Tank Effluent Pump (STEP) collection
system, a secondary/advanced wastewater treatment plant (WWTP), and a dual effluent disposal system (surface and groundwater discharge) within City limits. The wastewater system is designed
and operated to meet criteria set by the Washington Department of Ecology (Ecology) and specified in a National Pollutant Discharge Elimination System (NPDES) permit for these facilities.
Components of this system are summarized below from the Yelm Wastewater Technical Report (Parametrix, Inc., March 2007). A more detailed description of this system is provided in that
document.
Collection System. The STEP collection system consists of individual septic tanks located at buildings, or common septic tanks serving multiple residences or commercial structures. Solids
in the wastewater settle in the septic tank, and the relatively clear effluent is pumped through smaller-diameter pressure mains to the WWTP. These pipelines are generally located in
public rights-of-way and serve most, but not all, buildings within the City limits.
Treatment Plant. The City’s existing WWTP treats wastewater to meet secondary treatment standards for disposal to surface water, and also generates Class A (the highest quality) reclaimed
water that can be reused in non-potable applications, such as irrigation, groundwater recharge, and various industrial and commercial applications. Secondary treatment is achieved using
sequencing batch reactors. Additional treatment facilities, coagulation, and sand filters are used to generate Class A reclaimed water. The existing WWTP has the capacity to treat and
discharge 1.05 mgd of wastewater meeting secondary standards and 0.30 mgd (300,000 gallons per day) of reclaimed water meeting Class A standards.
Disposal System. Secondary treated effluent is currently discharged to surface water (i.e., to the Nisqually River) through an outfall located in the Centralia Power Canal. Direct discharge
to the river can also occur through an emergency outfall, but only when discharge to the Power Canal must be avoided due to low flow conditions or maintenance activities in the canal.
The City also has disposal facilities to infiltrate Class A reclaimed water into the ground using ponds (rapid infiltration basins) in Cochrane Park. Groundwater recharge is limited
at the present time by the capacity of the advanced treatment processes and requirements of the NPDES permit issued by Ecology.
The City’s wastewater system was designed to serve growth within Yelm and its UGA, but does not presently have sufficient capacity to handle the projected volume of wastewater that would
be generated by the Thurston Highlands Master Planned Community. Additional hydraulic, organic, and solids loading generated by Thurston Highlands would exceed the design capacity of
the City’s existing wastewater facilities.
The STEP conveyance system between the City’s WWTP and Thurston Highlands is not adequately sized to serve the proposed Master Planned Community. A system upgrade is proposed in will
be required to serve anticipation of additional development within the southwest area of the City’s UGA. It is was a condition of the Tahoma Terra Development Master Planned Community
(adjacent to Thurston Highlands on the West) to upgrade and upsize the existing STEP line from this Tahoma Terra area to the WWTP to an 8-inch line before xxx residential units are built
within Tahoma Terra.when required based on sewage flows from the Tahoma Terra Master Planned Community.
[Mark: When this information is available from Parametrix, please discuss here the capacity in the City’s existing sewer system available to allocate to new users, and the criteria that
will be used to determine how much of that capacity could be allocated to Thurston Highlands.]
Proposed Developed Conditions
The planning year for the Parametrix report was 2030, which is consistent with the projected buildout of the Thurston Highlands Master Planned Community. The Wastewater Technical Report
evaluated the requirements of the Preferred Alternative for development of the Master Planned Community. This report estimates wastewater effluent in direct proportion to water usage
as calculated in Section 4 of this report.
Master Plan Proposal
Similar to the water supply requirements of the project as calculated in Section 4 of this report, the projected wastewater volume that would be generated by the three conceptual land
use alternatives would differ by less than ten percent. The design wastewater flow used for this proposal is 70 gallons per capita per day (gpcd) (Parametrix, Inc., March 2007).
Preferred Alternative
The Preferred Alternative would have approximately 12,551 residents, resulting in an average daily wastewater flow of 878,570 gallons per day (gpd).
The average daily wastewater demand to serve total commercial (retail and office) development under the Preferred Alternative (960,000 square feet) would be approximately 155,000 gpd,
based on seventy percent water usage.
Combined average daily wastewater flow from schools is calculated to be 56,800 gpd (70% of water usage) with a total student population of 2,661. For other public facilities, like the
Regional Sports Complex, fire and/or police stations, an average daily wastewater sewer flow is projected to be approximately 54,500 gpd (5 percent of the total average daily wastewater
flow under any of the conceptual land use alternatives). For all public facilities, to including schools, the total average wastewater flow would equate to approximately 1,144,870 gpd
with the Preferred Alternative.
[Mark: The revised water use factor for students (per City Code), and student population per conceptual land use alternative (per YCS 2007 CFP), will change some numbers in this text
section, as well. This comment applies to the discussion of all three alternatives in Section 5.2.]
Traditional Development Alternative
The Traditional Development Alternative would have approximately 13,862 residents, resulting in an average daily wastewater flow of 970,340 gallons per day (gpd).
The average daily wastewater demand to serve total commercial (retail and office) development under the Traditional Development Alternative (630,000 square feet) would be approximately
101,430 gpd, based on seventy percent water usage.
Combined average daily wastewater flow from schools is calculated to be 54,120 gpd (70% of water usage) with a total student population of 2,958. For other public facilities, like the
Regional Sports Complex, fire and/or police stations, an average daily wastewater sewer flow is projected to be approximately 56,300 gpd (5 percent of the total average daily wastewater
flow under any of the conceptual land use alternatives). For all public facilities, to including schools, the total average wastewater flow would equate to approximately 1,182,200 gpd
with the Traditional Development Alternative.
Urban Village Alternative
The Urban Village Alternative would have approximately 10,999 residents, resulting in an average daily wastewater flow of 769,930 gallons per day (gpd).
The average daily wastewater demand to serve total commercial (retail and office) development under the Urban Village Alternative (1,500,000 square feet) would be approximately 241,500
gpd, based on seventy percent water usage.
Combined average daily wastewater flow from schools is calculated to be 54,120 gpd (70% of water usage) with a total student population of 2,067. For other public facilities, like the
Regional Sports Complex, fire and/or police stations, an average daily wastewater sewer flow is projected to be approximately 53,300 gpd (5 percent of the total average daily wastewater
flow under any of the conceptual land use alternatives). For all public facilities, to including schools, the total average wastewater flow would equate to approximately 1,118,800 gpd
with the Urban Village Alternative.
[Mark: Please check the highlighted number in the paragraph above. It seems unlikely that it would be the same as average daily wastewater flow from schools in the Traditional Development
Alternative.]
No Action Alternative
If no development were to occur on the Thurston Highlands site, there would be no requirement for extension of the City’s wastewater collection system to serve this
property, and no need to increase the capacity of the WWTP and disposal system. Existing City of Yelm wastewater collection, treatment and disposal facilities have sufficient capacity
to serve other anticipated growth within the incorporated area and UGA through the year 2030 (Parametrix, Inc., March 2007).
5.3 Design Requirements
Sewer service for the proposed development would be provided by the City of Yelm in accordance with the City’s Sewer Facilities PlanGeneral Sewer Plan, to be updated in 2008 and applicable
City and State regulations. New infrastructure would be required to serve the proposed Thurston Highlands Master Planned Community. Wastewater collected within the development would
be conveyed to the City of Yelm WWTP. Existing WWTP facilities would be expanded to meet the combined projected flows and loads for the City and Thurston Highlands. A gravity collection
system would require more improvements at the WWTP than a STEP collection system, primarily because of additional solids loading. Additional flow resulting from development of Thurston
Highlands would be discharged to groundwater within the City’s Urban Growth Area.
MORE DESCRIPTION OF ALTERNATIVE METHODS OF COLLECTION
The collection system alternatives are significantly different. A gravity collection system would use gravity-flow pipelines to convey wastewater to eight sewage pumping stations that
in turn would pump wastewater to the Yelm WWTP through a common pipeline. The STEP collection system would use septic tanks at each residence, each with pumping equipment to pump the
partially-treated wastewater to the Yelm WWTP. Solids accumulated in the septic tanks would be periodically removed by tanker truck and hauled away for disposal by a private contractor.
It is not possible to compare STEP and gravity collection systems independently without also considering the entire wastewater collection, treatment, and disposal system as a whole.
Because septic tanks capture solids, reducing organic and solids loading of the WWTP, STEP collection systems are an integral part of the treatment process. STEP
collection systems also minimize the potential for (and ultimately the volume of) infiltration and inflow into the collection system, thereby reducing the hydraulic treatment capacity
needs of the WWTP.
The recommended alternative in the Yelm Wastewater Technical Report is to extend the City’s existing system of STEP tanks and pumps, STEP mains ranging in size from 2-inch to 8-inch
diameter, possible gravity mains and manholes. The Yelm City Council City of Yelm will make the final decision during the Master Site Plan approval process re: regarding the type of
collection system (STEP or gravity) to serve Thurston Highlands as part of the update to its General Sewer Plan scheduled for 2008.
GENERALLY NEED MORE DESCRIPTION OF THE TWO COLLECTION SYSTEMS AND THE PROS AND CONS WITHIN EACH AREA.
5.4 Project Impacts
Any of the three conceptual land use alternatives would result in similar impacts and require similar mitigation measures for wastewater collection, treatment and disposal, as the actual
volume of wastewater that would be generated would be similar. The Urban Village Alternative (highest density) would possibly result in less infrastructure in the ground given that more
vertical development would cover a smallerfootprint of land; however, impacts to the overall City system downstream of the site would be close to the same as the other alternatives.
As described in the Yelm Wastewater Technical Report (Parametrix, Inc., March 2007), constructing a gravity collection and conveyance system within Thurston Highlands would result in
vast differences in overall impacts to the system compared to a decision to instead construct a STEP collection and conveyance system consistent with the type of system currently in
operation throughout the City. Combining the two systems would be impractical, as the existing WWTP is designed to handle only wastewater from a STEP system, not the solids that would
be present with a gravity system. If a gravity system were selected, the City would need to consider replacing the existing STEP system throughout its service area. The comparative short-term
and long-term advantages and disadvantages of the two types of systems under consideration are described below under Potential Operational Impacts, and in more detail in the Yelm Wastewater
Technical Report (Parametrix, Inc., March 2007).
Potential Construction Impacts
Construction of a new STEP collection system (with vaults) and/or gravity sewer mains would be required throughout the Thurston Highlands Master Planned Community. Either conveyance
system would be constructed within public rights-of-way or easements located under, or adjacent to public streets. The proposal is to construct the wastewater collection system infrastructure
as Tahoma Boulevard and local access streets are extended through Thurston Highlands, with final paving to follow the completion of utilities. Construction activities related to installation
of the collection and conveyance mains may include temporary disruptions in service to some customers; noise and dust during the construction phase; and construction-related traffic
to deliver pipe and vault materials to the sites.
[Mark: If there would be any off-site construction impacts to increase line sizes or add collection lines between Thurston Highlands and the WWTP or disposal sites, please describe these
construction impacts, as well. Please also review Section 6.3.4 of the Parametrix report for possible additions to this text; it does a more thorough job of describing and comparing
the construction impacts of the two different types of collection systems.]
The WWTP is sized and currently permitted to treat 1.0 million gallons per day of wastewater. A permit modification and construction would be required to upgrade the facility to 2.0
million gallons per day to provide the additional capacity needed to serve the Thurston Highlands Master Planned Community. Alternatively, a second smaller (satellite) WWTP could be
constructed within Thurston Highlands, if considered by the City to be an economically feasible component of their system. Under either scenario, WWTP construction or expansion would
result in construction-related traffic for transport of material to/from the site; noise and dust associated with earthwork activities and the operation of equipment on the site.
If a gravity collection and conveyance system were selected to serve Thurston Highlands, off-site construction disturbance would be more significant than with the STEP system alternative.
Parallel sewer lines of different size would likely be constructed. A smaller diameter pipeline would be used to serve early phases of development. As flows increased with future development,
the larger pipeline (or both) would be used to convey wastewater to the treatment plant. This operational strategy would better optimize flow velocities within the pipeline, thereby
minimizing odor concerns. However, dual pipelines would result in construction impacts of greater magnitude, due to the additional width of the construction corridor. Additional improvements
would also be required at the existing WWTP. A headworks would need to be added to process solids conveyed in a gravity collection system.
A detailed description of potential impacts to the existing WWTP based on the collection and disposal options under consideration is provided in Chapter 6 of the Yelm Wastewater Technical
Report (Parametrix, Inc., March 2007).
Potential Operational Impacts
Four factors are presented in the Yelm Wastewater Technical Report (Parametrix, Inc., March 2007) for the City’s consideration in selecting between a STEP collection system or gravity
sewer collection system for Thurston Highlands: construction phasing, system reliability, system life cycle considerations, and maintenance requirements.
In general, STEP systems are better suited for phased development, as individual septic tanks can be added to the system as needed based on the actual schedule of development. Sizing
of STEP system pipelines to convey a wider range of flows would be simplified because the wastewater is pumped. In contrast, a gravity collection system would need to be designed and
constructed based on the projected build-out population.
The primary reliability consideration for wastewater collection systems is the ability to provide redundant storage or a standby power source during power outages. In the event of a
power outage, septic tank pumps would not operate. The tanks would be susceptible to overflows if power outages were to exceed 24 hours. A gravity system would be more reliable in this
situation, as each pump station would be equipped with a dedicated emergency generator and transfer switch that would automatically power the facility if the main power source was disrupted.
Life cycle considerations are related to the design life of the collection system equipment, including pumping equipment, septic tanks, and pump station structures. The design life of
a septic tank is typically 20 to 30 years. In contrast, gravity collection system pipelines and pump station structures can be expected to have a service life of 50 years. Pumping equipment
for either STEP collection or gravity systems typically has a design life of 10 to 15 years. The larger pump stations in a gravity system typically have remote monitoring equipment and
alarms to notify Public Works Department staff of problems. Individual STEP system septic tanks and pumps cannot feasibly be monitored or maintained as frequently as the larger pump
stations in a gravity system. In general, STEP system components are more susceptible to total failure; i.e., City staff generally receive notification from individual property owners
only after a tank has leaked or a pump has failed.
If a STEP collection system is selected to serve Thurston Highlands, maintenance requirements would increase for the City’s Public Works Department in proportion to the increase in the
number of STEP vaults in the City’s system. Additional staff and equipment would be required to maintain the additional vaults. The benefit of this type of system, however, is that
the Public Works Department has the necessary equipment required to operate and maintain a STEP system, and staff are accustomed to these procedures. A gravity system would require additional
staff training and the purchase of equipment, such as a Vactor truck, for periodic removal of accumulated solids.
Regardless of the collection system alternative selected, it would be necessary to increase the size of the City’s existing WWTP to handle the additional volume of wastewater, and to
retrofit the plant with processing equipment to handle the addition of solids.
[Mark: Would the City experience operational impacts associated with a larger treatment plant? If a gravity system were selected, it seems that there would be additional maintenance
requirements for the headworks. Please add a brief paragraph to address this issue.]
5.5 Mitigation Measures
Mitigation measures for the wastewater collection, treatment, and disposal requirements of any of the three conceptual land use alternatives would be roughly the same, given the similar
size of development and resulting impacts. The type of collection and conveyance system would influence mitigation requirements to address the impacts identified in Section 5.4, above.
Incorporated Plan Features
Thurston Highlands, L.L.C. is coordinating with the developers of adjacent properties to size STEP mains that terminate at the site boundary to handle expected flows that would be generated
by the Master Planned Community.Collection and conveyance lines within Thurston Highlands would be constructed within City rights-of-way or easements. Treatment and disposal options
will be considered by City decision makers during adoption of an updated Sewer Comprehensive PlanGeneral Sewer Plan, and during the Thurston Highlands Master Site Plan approval process.
Applicable Regulations and Commitments
The Thurston Highlands Master Planned Community would comply with applicable wastewater collection, treatment, and disposal criteria set forth by the City of Yelm in their Sewer Facilities
PlanGeneral Sewer Plan, and all other applicable regulations and permit conditions. The City will be updating its Sewer Facilities Plan General Sewer Plan to address infrastructure requirements
to serve anticipated growth in the Highlands and elsewhere in the City’s UGA.
Other Recommended Mitigation Measures
Over the course of the 10- to 30-year development of the Master Planned Community, and with the extension of fiberoptics throughout the project, it is possible that new technology (e.g.,
some form of telemetry system) could be implemented to monitor the function of STEP system components.
[Mark: Would it be possible for Thurston Highlands, L.L.C. to commit to do something within the development (e.g., through the Homeowners’ Association) to monitor the function and condition
of STEP system components to address the most significant concern identified in Section 5.4.]
MARK: NICE TRY BUDDY!
5.6 Phased Development
Phased development of the wastewater collection system may or may not coincide with phased construction of the Master Planned Community. A STEP system would adapt to changes in the development
phasing easier than a gravity system, as described in Section 5.4, above. A gravity system would require more thought during the design phase to serve future areas that may utilize gravity
lines. Lift station placement would also require advance planning.
RE-USERECLAIMED WATER
6.1 Existing Conditions
Reclaimed water is used in the City of Yelm at Cochrane Park and some irrigation/landscaping applications during summer months. The reusereclaimed water is generated by filtering wastewater
at the existing City Wastewater Treatment Plant (WWTP) into Class A reclaimed water. From the WWTP, the reclaimed water is conveyed using “purple pipe” of pipe of various sizes. Purple
pipe Reclaimed water distribution lines has have been installed in Tahoma Terra to the northeast of Thurston Highlands and main lines have been sized adequately for continuation into
Thurston Highlands.
A more detailed description of the system, including permitting and capacity are discussed in the Yelm Wastewater Technical Report prepared by Parametrix in March of 2007.
6.2 Proposed Developed Conditions
All phases of Thurston Highlands will install “purple pipe” for reclaimed water distribution lines. The decision to utilize reclaimed water in the area will be determined by the City
of Yelm based on economical and operational feasibility. As part of a City-wide mitigation plan for the consumptive use of water, the Thurston Highlands site is being evaluated as a
possible location for the infiltration of reclaimed water to recharge the regional aquifer.
6.3 Design Requirements
Reclaimed water production is regulated by RCW Chapter 90.46 RCW and the State Water Reclamation and Reuse Standards CITE NEEDED WAC??? (Ecology and DOH 1997). Conveyance would be regulated
by City of Yelm standards.
6.4 Project Impacts
Any of the three conceptual land use alternatives would have similar impacts.
Potential Construction Impacts
Construction-related impacts would be very minimal as purple pipe for the conveyance of reusereclaimed water would be constructed within roadway rights-of-way, or other public easements,
concurrent with the construction of other underground utilities. Improvements to the City’s WWTP would occur as part of any upgrade associated with upsizing the facility beyond current
allowable capacity. Interruptions could occur as new pipe is connected into existing pipe. However these would be very minimal, if any.
[Mark: What would cause an interruption in service associated with purple pipe installation?]
Potential Operational Impacts
Given the overall acreage of Thurston Highlands and the number of possible users of any reclaimed water, the amount of purple pipe and associated conveyance infrastructure required would
increase the maintenance and operational needs by xx%.
Reclaimed water can also be used beneficially for ground water recharge via surface percolation, provided that it meets the Groundwater Recharge Criteria found in RCW Section 90.46.080
RCW (Parametrix, Inc., March 2007). The Thurston Highlands property contains has some areas favorable to infiltration that may be conducive for groundwater recharge; however, it is
anticipated that these favorable areas will may be needed for stormwater infiltration. There may not be enough favorable areas for both reclaimed water groundwater discharge and stormwater
infiltration during the winter months, but it may be possible for groundwater recharge during the summer months when stormwater infiltration is not needed.
MARK [I WOULD RATHER BE A LITTLE MORE POSITIVE HERE AND TALK ABOUT THE POSSIBILITY OF THE USE OF THE SPORTS FIELDS FOR RECLAIMED INFILTRATION THAT IS BEING MODELED BY PgG AND MAY BE
FURTHER ANALYIZED AS PART OF A MITIGATION PACKAGE AS PREVIOUSLY NOTED IN YOUR TEXT.
6.5 Mitigation Measures
Mitigation measures associated with any of the three conceptual land use alternatives would be similar, given similar impacts.
Incorporated Plan Features
Purple Reclaimed water pipe will be installed throughout Thurston Highlands for the purpose of maximum flexibility of reclaimed water use when deemed appropriate by the City of Yelm.
Uses could include many of the same uses currently used today by the city, including wetland recharge and landscape/irrigation needs on the site or any beneficial use as defined in
RCW 90.46. Additionally, reclaimed water could be used to irrigate the large Regional Sports Complex year round, pending good soils conditions present after final site grading.
Applicable Regulations and Commitments
There are no known applicable regulations or commitments required for reclaimed water use, other than to abide by appropriate regulations.
[Mark: The above statement is redundant and circular. Can you improve on it?]
Other Recommended Mitigation Measures
Reclaimed water has successfully been used in other locations for not only irrigation and wetland recharge uses, but for fire flow capacity as well. As technology continues to advance
in this area, the City of Yelm could consider the possibility of storing reclaimed water in commercial areas for fire flow needs to reduce the demand for domestic water for this purpose.
MARK: PLEASE EXPAND ON THIS A BIT AND PERHAPS TALK ABOUT GROUNDWATER INFILTRATION OR GROUNDWATER STORAGE.
6.6 Phased Development
It is anticipated that Phase 1 of Thurston Highlands will follow the same practice as the various divisions in Tahoma Terra which was to install the purple pipe mainline and service
lines for future use. Future phases of Thurston Highlands would have an opportunity to use newer technology for reclaimed water uses.
7.0 ELECTRICAL POWER
Puget Sound Energy (PSE) and Centralia Utilities are the electrical power service providers in the project area. PSE provided a detailed account of their facilities and abilities to
meet the needs of Thurston Highlands in a letter to Grant Beck, City of Yelm Community Development Director on May 3, 2007. Centralia Utilities was also consulted regarding their potential
interest and capability to serve the Thurston Highlands Master Planned Community, but they have declined to provide any service. Centralia Utilities will work with the developer to
relocate the existing transmission lines that run diagonally across the western portion of the site.
7.1 Existing Conditions
Electrical power to the Yelm area including the Thurston Highlands property is served by PSE’s transmission lines coming from the Lake Sinclair sub-station to an existing substation
(Yelm Substation) located at 16300 Railway Road S.E. An additional transformer at this substation may be needed to address near-term growth from proposed developments.
All power lines that would feed the Thurston Highlands property are below-grade facilities located within public road rights-of-way, or within adjacent easements. Conduit and electrical
line capacity to serve the initial phase(s) of Master Planned Community development on the Thurston Highlands site were placed within the Tahoma Boulevard right-of-way as part of the
Tahoma Terra development.
The Rainer Substation was rebuilt in 2005 and 2006 to increase the electrical load capacity in the town of Rainer and unincorporated areas northeast of Rainer. The initial load demand
from Master Planned Community Development on the Thurston Highlands site could be reinforced from the Rainier substation. (Amy L. Tousley)
[Mark: Please properly cite the personal communication with Amy Tousley, PSE.]
Centralia Utilities has a xx-year old transmission line with a capacity of xx that crosses the western portion of the Thurston Highlands site in a NE/SW direction. The transmission
line is xx-feet in length, and originates from the Centralia Power hydro facility on the Nisqually River. Centralia Utilities has a 50-foot wide easement across the property for access
and maintenance of their poles and lines. There is no local service available from these lines; they simply cross the site to serve electrical needs in the City of Centralia approximately
18 miles to the southwest.
[Mark: Please fill in the blanks in the paragraph above.]
7.2 Proposed Developed Conditions
PSE maintains spreadsheets of projects identified through development applications sent by local permitting jurisdictions. They also implement a Growth Management Act Facilities Plan
for Thurston County through the individual comprehensive plans in the County. The County’s Comprehensive Plan Utilities Element was last amended in 2004. Based on information received
to-date regarding the Thurston Highlands development, PSE has determined that there is capacity to serve this future growth through its transmission and distribution systems in the near
future. However, PSE may need to accelerate the timing of some planned transmission and distribution improvements depending on the customer growth rate in the area (PSE, May 30, 2006).
One of the key factors PSE uses in assessing impact is not only the types of growth involved with a project, but the scale of the use as well. For a project of this size with more than
5,000 residential units planned, the size of residential units will vary and the impact of a 1,000 square-foot multi-family unit is much less than a 3,000 square-foot single-family home.
PSE uses power estimates for heating, lighting and appliances ranging from 4.97 kW for 1,000 to1,500 square-foot Multi-Family units, to 5.44 kW for 1,000 to 1,500 square-foot Duplexes,
to 7.78 kW for 3,000 to 3,500 square-foot single family homes. For a project like Thurston Highlands, PSE would use an average square-footage for the various residential types. PSE’s
estimates for residential electrical loads are presented in their letter to Mr. Grant Beck (PSE, May 3, 2007)
[Mark: Please append this letter to your report, and refer readers here to that Appendix.]
Likewise, it is difficult to estimate the commercial electrical power needs based solely on square-footage. Differing uses could result in greater or lesser demands; therefore, PSE
has estimated electrical needs based on typical large-scale commercial centers in neighborhood centers. PSE’s estimates for commercial electrical loads are presented in their letter
to Mr. Grant Beck (PSE, May 3, 2007). [Please refer to Appendix location.]
PSE would serve the Thurston Highlands Master Planned Community from the existing Yelm Substation located on Railway Road SE, and from construction of a new distribution substation to
be located south of SR 507. Based on the conceptual site plan reviewed by PSE in May 2006, the load needs of the Thurston Highlands Master Planned Community were estimated to require
about two-thirds of the capacity of a typical substation. PSE is able to meet the load impacts anticipated in the Phase 1 development plan within the existing electrical distribution
and transmission system facilities (PSE, May 3, 2007).
It is an element of the Thurston Highlands proposal to relocate Centralia Utilities overhead transmission lines from the existing diagonal easement across the property to the perimeter
of the site along the west and north property boundaries adjacent to Fort Lewis. Centralia Utilities has requested that a 100-foot easement be granted for the new location to accommodate
future expansion, although they’ve admitted they have no current plans to expand the system. As a result, a 50-foot wide easement may be enough to satisfy their needs for access to
and maintenance of the single power line.
PSE will need a utility corridor as well for new transmission lines per the Yelm Area Transmission Plan. This corridor could either locate new transmission lines within this same easement
benefiting Centralia Utilities, or look for alternative routes (cross-country or along County right-of-way). Co-locating with Centralia Utilities would be consistent with Growth Management
Act policies; however, PSE cannot share transmission poles with Centralia Utilities. Therefore, a second system of poles would be necessary, resulting in the need for at least a 100-foot
wide easement. PSE’s long-range planning anticipates extending overhead transmission lines south from the Lake Sinclair facility to a new substation south of SR 507.
7.3 Design Requirements
Thurston Highlands electrical service requirements will be coordinated with PSE Engineering and Construction Departments during the preparation of construction documents for the project.
The development will continually coordinate with PSE on long-range planning/scheduling needs, but the actual design of facilities will occur as each phase of development submits subdivision
applications to the City of Yelm.
Relocation of Centralia Utilities transmission lines will be coordinated with Centralia Utilities Engineering and Construction Departments. The timing of these efforts will occur as
the first land use application results in the need for relocation of this power line, and will address the entire length of the transmission line across the property.
7.4 Project Impacts
Potential Construction Impacts
Phase 1 construction impacts would include coordinating location of underground conduit within the public right-of-way of the Tahoma Boulevard extension and adjoining residential streets
to meet the expanded demand of the Thurston Highlands Master Planned Community. Electrical service to all the new buildings would be provided in conjunction with PSE by developing a
site distribution system map. PSE has stated that they are able to meet the load impacts anticipated in the Phase 1 development plan within the existing electrical distribution and
transmission system facilities (PSE, May 3, 2007).
For future phases, however, the existing substation in Yelm would need to be expanded (by adding a transformer) in order to meet ongoing development demands in the Yelm area, and to
implement further reliability improvements for a third transmission line in the near future. These capacity and reliability improvements would require expansion of the existing footprint
of the Yelm substation (PSE, May 30, 2006); and (City of Yelm, May 23, 2006).
New transmission lines from the Lake Sinclair facility to Yelm would likely follow existing roadway rights-of-way as PSE has franchise agreements with Thurston County and the City of
Yelm. Short-term traffic delays may be expected as the facilities are constructed adjacent to operational roadways within some of the rights-of-way.
If the No Action Alternative were selected, PSE would not extend its electrical power distribution system into the Thurston Highlands site.
Potential Operational Impacts
A new distribution substation has been identified through PSE’s long range planning. The exact location has not yet been determined. While PSE’s plans have tentatively located the proposed
substation south of the Thurston Highlands Master Planned Community along SR 507, PSE believes it is also important to include the potential site of a substation, most likely a 25 MVA,
within Thurston Highlands (PSE, May 30, 2006). If sited within the development, this substation would include the construction of new overhead 115 KV transmission lines from the new
off-site substation to this new on-site substation. All new facilities would be sized in anticipation of full build-out of the Master Planned Community. The actual increase in demand
for electrical power would be phased over the projected build-out of the planned improvements.
PSE has indicated it could take anywhere from 3 to 5 years to acquire property and build a new substation. They anticipate starting the process for acquiring land and building a new
substation south of SR 507 in 2008. PSE anticipates having a fully-energized facility by 2012 to serve whichever conceptual land use alternative is selected for Thurston Highlands.
This time frame would correspond to the completion of Phase 1 and the initiation of Phase 2 of Master Planned Community development.
7.5 Mitigation Measures
In preliminary conversations with PSE, it was noted that the existing facilities have capacity to serve the Phase 1 development. Future phases will require additional expansions and
upgrades, but PSE would have the ability to meet these needs with appropriate long-range planning and coordination with the developer and local jurisdictions.
Incorporated Plan Features
Mitigation for construction impacts would involve installing electrical facilities within dedicated rights-of-way to avoid impacts to private property. PSE, using one of its authorized
contractors, would perform this work and be required to work with either Thurston County or the City of Yelm on proper traffic control while work occurs on operational roadways.
Thurston Highlands Phase 1 would most likely be served from the Yelm Substation, but the Rainer Substation could help subsidize load demands. Underground conduit facilities are already
in place in Tahoma Boulevard through Tahoma Terra to serve the initial phase(s) of Master Planned Community Development.
Applicable Regulations and Commitments
Per Yelm City Code, the electrical distribution facilities for the Master Planned Community would be constructed through an underground distribution system, except that PSE’s substation
facilities and 115 kV transmission lines would be above-ground. If there will be any bridge crossings, PSE would like to coordinate attaching lines to these, or boring beneath (City
of Yelm, May 23, 2006).
[Mark: Was the highlighted source really the City of Yelm, or PSE? Please check/fix this, and provide full citations in a References section.]
Other Recommended Mitigation Measures
Mitigation measures to minimize electrical demand generally consist of using high-efficiency lighting and heating, ventilating, air conditioning (HVAC) systems. The residential and
commercial developments should be encouraged to use such measures as reasonably practical within standard practices at time of development.
7.6 Phased Development
Phased extension of the electrical distribution system through the Master Planned Community may or may not coincide with phased development of the project. The developer will maintain
close communication with PSE to coordinate the extension of power in accordance with a mutually-agreeable phasing schedule. Load analyses will be developed at the time of application
for specific subdivision approvals. Electrical lines will be located within designated easements with ease of access for inspection
and repair. For ease of construction and to minimize conflicts with other utility services, “bubble” easements may be required, to expand the width of the easement at vault locations.
NATURAL GAS
Puget Sound Energy (PSE) currently provides natural gas service within the area that includes the Thurston Highlands site, and anticipates customary natural gas service to be constructed
throughout the Master Planned Community. Based on information they have reviewed to date, they have indicated there is capacity in their existing system and proposed improvements to
serve future growth through their natural gas distribution system.
HBH Propane and Ferrellgas, L.P. provide propane service in the area. Both would entertain the possibility of serving the Thurston Highlands site, or various portions of development.
[Mark: Was the highlighted source really the City of Yelm, or PSE? Please check/fix this, and provide full citations in a References section.]
8.1 Existing Conditions
As part of PSE’s long-range planning program, on-going natural gas improvements have been constructed in the Yelm area to meet existing and future demands. PSE recently completed installation
of an 8-inch diameter natural gas main along Longmire Road, to accommodate existing and anticipated growth in the southwestern portion of the City (PSE, May 3, 2006). This gas main presently
terminates approximately xx feet east of the Thurston Highlands site boundary.
[Mark: Please fill in the blank in the paragraph above.]
As part of PSE’s on-going long-range planning, improvements have been constructed in the Yelm area to meet existing and future demands. PSE had projects under design and construction
in the Spring of 2007 to improve system capacity as part of the Killian Road, Stevens Road and Main Street public improvement projects. These projects address growth anticipated on
the Thurston Highlands site and in the overall area by constructing 8-inch mains that are either new, or replace smaller 2-inch lines currently in-place.
PSE plans to rebuild the Town Border Station by the end of 2007. This is the district regulator that feeds the intermediate pressure system into Yelm.
Design is also underway to rebuild the Yelm Gate Station in the near future. This Station is the district regulator that feeds high pressure lines that feed the intermediate pressure
system.
8.2 Proposed Developed Conditions
The developed condition of any of the three conceptual land use alternatives would result in a similar demand for natural gas service. Only the No Action Alternative would differ, as
no utilities infrastructure would be required.
Based on information received to-date regarding the proposed Thurston Highlands Master Planned Community and alternatives, PSE has determined that there is capacity in their existing
system to serve this future growth (PSE, May 3, 2007). Based on the customers to be served, PSE anticipates typical natural gas main and services to be constructed throughout the development
feed by an 8-inch loop main. Applications for gas service to commercial uses will be submitted for review. Installation of the gas lines and meters will be coordinated with the contractor
during construction. PSE’s estimates for residential and commercial natural gas loads are presented in their letter to Mr. Grant Beck (PSE, May 3, 2007).
[Mark: Please append this letter to your report, and refer readers here to that Appendix.]
As an alternative energy source, propane could be considered for use in the Thurston Highlands development, instead of or in addition to natural gas. Although this service is not being
considered for large scale distribution, it is possible that propane could be used on a case-by-case basis for various land use applications. Propane service on a large-scale basis
would require installing onsite storage tanks (multiples of 30,000-gallon tanks) and underground distribution lines. HBH Systems prefers a mounded above-ground installation, for ease
of inspection, 24/7 security monitoring, and minimal optimum aesthetic compatibility. The propane supply would be trucked to onsite storage tanks (City of Yelm, May 23, 2006).
8.3 Design Requirements
All information regarding natural gas service to the Thurston Highlands Master Planned Community would be coordinated with PSE Engineering and Construction Departments during construction
document preparation. The developer would continually coordinate with PSE on long-range planning/scheduling needs. The actual design of facilities would occur at the time of each subdivision
application to the City of Yelm.
If propane service is utilized for any portion of the development, similar coordination would be required with the liquid propane service provider.
8.4 Project Impacts
Potential Construction Impacts
Construction impacts for Phase 1 would include coordinating the location of underground natural gas mains within the public right-of-way of the Tahoma Boulevard extension and adjoining
residential streets to meet the expanded demand of the development. Natural gas service could be provided to all the new buildings by developing a site distribution system map. PSE
has stated that they are able to meet the load impacts anticipated in the Phase 1 development plan within the existing natural gas distribution system facilities (PSE, May 3, 2007).
Similar impacts would be associated with future phases of development. PSE facilities and improvements under design/construction have the capacity to serve all of Thurston Highlands
without further need of off-site improvements to their systems.
[Mark: Please cite the source of the last statement above.]
Potential short-term impacts to natural gas service during installation of new distribution lines could occur. The impact of these short-term interruptions would affect small areas
that could be controlled by isolation within the transmission system.
Construction impacts associated with propane use would include delivery of the large storage tanks to the facility and separate distribution piping within the right-of-way or easements
to be provided.
Potential Operational Impacts
Operational impacts would include a larger distribution system for PSE to maintain. Infrastructure is already being designed and/or constructed to satisfy the overall demands of area
growth, including a Master Planned Community on the Thurston Highlands site.
Operational impacts associated with propane service would include dedication of easements for storage tank locations. Access and security fencing would be required at each location.
[Mark: If there would be safety concerns associated with large propane tanks within the development, please discuss this here.]
8.5 Mitigation Measures
Incorporated Plan Features
Mitigation for construction impacts would involve constructing facilities within dedicated right-of-way to avoid impacts to private property. PSE, using one of its authorized contractors
would perform this work and be required to work with either Thurston County or the City of Yelm on proper traffic control while work occurs on operational roadways.
Applicable Regulations and Commitments
All proposed natural gas system improvements and construction would be coordinated with PSE Engineering and Construction Departments.
Above ground propane storage tanks and enclosures would be designed and constructed with the propane carrier and per applicable state and local regulations for access, maintenance and
security.
Other Recommended Mitigation Measures
Inconveniences during installation of new natural gas distribution lines could be minimized by accomplishing the switchover at a time of low building use (such as evenings or weekends).
Measures that could be taken to minimize natural gas demand generally coincide with measures that would increase building envelope insulation and therefore heat loss. The residential
and commercial developments should be encouraged to use such measures as reasonably practical within standard practices at time of development.
If large propane tanks were installed within the development, landscape screening should be required to mitigate aesthetic impacts.
8.6 Phased Development
Phased extension of the natural gas system through the Thurston Highlands site may or may not coincide with phased development of the Master Planned Community. The developer will maintain
close communications with PSE throughout the Thurston Highlands development period. Load analyses will be prepared at the time of application for subdivision approvals. The natural gas
lines will be located within public rights-of-way or a designated easement with ease of access for inspection and repair.
It is not anticipated that propane will be used on a large-scale basis that would result in phased construction. Instead, propane may be requested on a case-by-case basis by actual
users within the development.
9.0 TELECOMMUNICATIONS
Ycom Networks/Fairpoint Communications, Comcast, and Digiteria/Equity provide telecommunications, internet services, and fiberoptics within the project area. Based on correspondence
with personnel from each utility, they are all interested and planning to provide services to the Master-Planned Community (personal communication with Tim Hite, Fairpoint Communications,
Senior Engineer, June 4, 2007; Scott Morrison, Comcast, SWPS Outside Plant Construction Engineer, June 4, 2007; John Petersen, Digiteria, June 20, 2007).
9.1 Existing Conditions
Ycom Networks or Fairpoint Communications (Fairpoint) has extended their fiber optic network to an easement site located within Tahoma Terra Division 1 and 2. Their node at this location
is capable of serving 864 customers, but currently only 30 are served. Plans are in-place to extend this network into Tahoma Terra Divisions 3 through 8, with capacity to also extend
into Thurston Highlands. The existing network has been designed to provide their Triple Play and Business services (personal communication with Tim Hite, Fairpoint Communications, Senior
Engineer, June 4, 2007).
Comcast has also extended their service into Tahoma Terra, with capacity to extend into Thurston Highlands. The size and location of facilities vary; however, they coincide horizontally
with electrical power locations (personal communication with Scott Morrison, Comcast, SWPS Outside Plant Construction Engineer, June 4, 2007).
Digiteria has also extended their service into Tahoma Terra, and has the capacity to extend into Thurston Highlands. They have a 36-foot by 36-foot data center building in Tahoma Terra
that can serve all of Tahoma Terra and Thurston Highlands. The size and location of other facilities vary. As with Comcast facilities, Digiteria systems coincide horizontally with
electrical power locations (personal communication with John Peterson, Digiteria, June 20, 2007).
9.2 Proposed Developed Conditions
The developed condition of any of the three conceptual land use alternatives would exert a similar demand for telecommunications services. Only the No Action Alternative would differ,
in that no infrastructure would be required.
Based on information received to-date regarding the proposed Thurston Highlands Master Planned Community and alternatives, all three telecommunications providers have networks with capacity
to provide service to the site (personal communication with Tim Hite, Fairpoint Communications, Senior Engineer, June 4, 2007; Scott Morrison, Comcast, SWPS Outside Plant Construction
Engineer, June 4, 2007; John Peterson Digiteria, June 20, 2007). Only utility infrastructure within the development would be required. All utilities would be placed within road rights-of-way,
or other dedicated easements.
9.3 Design Requirements
Telecommunications installation will follow the regulated requirements of each provider. Underground installation would follow electrical power installation (using the same trenches),
and precede the extension of natural gas.
9.4 Project Impacts
Potential Construction Impacts
Fairpoint will provide telecommunications services for the Thurston Highlands Master Planned Community. Telecommunications vaults and service lines would be installed in the same trench
with electrical service lines. ‘Bubble’ easements (i.e., wider than the standard 10-ft easement) would be requested at vault locations. The requested dimension of the bubble easements
is 48 inches x 1-ft setback (Fairpoint Communications, May 26, 2006). Approximately six to eight separate sites (one for approximately every 864 lots) within the Master Planned Community
would be required to establish small offices (node locations), approximately 20 feet by 20 feet in area, preferably in an easement adjacent to a roadway.
Comcast and Digiteria would also require vaults and service lines in the same trenches as electrical power and within the same ‘bubble easements’ to expand their network service area.
Potential Operational Impacts
Operationally, there appear to be no adverse impacts associated with providing telecommunications services to the Master Planned Community, as all service providers have adequate capacity
to handle the development needs.
9.5 Mitigation Measures
Incorporated Plan Features
At this Master Plan level of review, there are no known measures or features proposed to minimize construction impacts as the facilities would be located underground within road rights-of-way
or other easements.
Applicable Regulations and Commitments
All proposed telecommunication system improvements and construction would be coordinated with each provider at the time site development approvals are sought. These systems would be
installed in compliance with applicable regulations.
Other Recommended Mitigation Measures
As no adverse impacts have been identified, there are no other recommended mitigation measures for telecommunications service.
Phased Development
Phased extension of the telecommunication distribution system through Thurston Highlands site may or may not coincide with phased development of the Master Planned Community. The developer
will maintain close communication with the communication providers to coordinate the extension of the utilities in accordance with a mutually-agreeable phasing schedule. Load analyses
will be developed at the time of application for each subdivision approval. Communication lines and conduit will be located within designated easements with ease of access for inspection
and repair. For ease of construction and to minimize conflicts with other utility services, “bubble” easements may be required, to expand the width of the easement at vault locations.
APPENDICES
Appendix A
Master Planned Community
Conceptual Land Use Alternatives
Appendix B
Soil Logs and Soil Infiltration Information
Figure 3.1 Soils Logs and Soil Infiltration
Appendix C
Site Drainage Basin Map
Appendix D
City of Yelm, Staff Report from September 19, 2006
“Principles of Sustainable Development
MARK DOES THIS BELONG HERE OR ELSEWHERE IN THE EIS????
Appendix E
WWHM Drainage Calculations
Appendix F
DOE Approved BMP’s
Appendix G
Tahoma Boulevard Cross-Section
Appendix H
Preliminary Sewer Loading Calculations
Appendix I
Preliminary Re-UseReclaimed Water Calculations