In the Spring of 2000, Spokane County Utilities began the process of
developing a Wastewater Facilities Plan to identify wastewater
facilities and programs that must be implemented to meet the long-term
needs of the County. Spokane County began the wastewater planning
process to evaluate future County wastewater service areas, project
future wastewater flows, and develop recommendations for new wastewater
treatment facilities and reclamation programs.
This chapter provides an overview and description of the alternatives
being considered for expansion of Spokane County's wastewater treatment
facilities. The County is considering five alternatives for
treatment facility locations and configurations. In addition, the
County is considering various alternatives for other system components
including demand management, effluent end use, and biosolids management.
The other system component programs are also presented in this chapter.
The evaluation criteria for screening the initial treatment facility
alternatives and the alternatives considered but not selected are
described. In addition, this chapter describes the No Action
alternative, as required by the Washington State Environmental Policy
Act (SEPA).
The Spokane Advanced Wastewater Treatment Plant (SAWTP) is operated by
the City of Spokane. The County has an interlocal agreement to
send up to 10 mgd to the SAWTP. This alternative would expand the
existing SAWTP to handle all flows from the County and City through the
year 2025. The level of treatment would be upgraded to tertiary
treatment. The County's average flows in the year 2025 are
projected to be 22 mgd with the combined City and County flows estimated
to be 65 mgd. The capacity of the SAWTP is currently rated at 40
mgd. This Alternative would require a new interlocal
agreement between the County and City.
This Alternative would require expansion of the County and City
conveyance systems, especially the system that conveys flows from the
Valley to the SAWTP. The current interlocal agreement between the
County and City sets the allowable peak flow through the City's
interceptor system at 15.5 mgd. Projected peak flows from the
Valley are 37 mgd. Conveyance of the amount of flow in excess of
15.5 mgd will require pumping through a new forcemain to the SAWTP.
This would require two new pumping stations and approximately 8 miles of
forcemain. The forcemain would be routed primarily through densely
developed portions of the City. Segments of the City's interceptor
system would also need to be expanded in North Spokane.
This alternative would locate a new 12-mgd plant in the Spokane Valley
east of the Spokane city limits. Flows generated in the Spokane
Valley would be sent to the new plant. The new plant would provide
tertiary treatment and would discharge treated effluent to the Spokane
River below Upriver Dam. The County would retain its current
10-mgd capacity allocation at the SAWTP and all flows generated in North
Spokane and a portion of the flow from the Spokane Valley would continue
to be sent to the SAWTP. The County has identified this
alternative as the Preferred Alternative.
The new plant most likely will be located along the North Valley
interceptor and will require a new influent pumping station to lift the
North Valley flow into the treatment plant. A new pump station and
force main will also be required to convey flow from the Spokane Valley
interceptor to the new treatment plant. This would substantially
reduce the amount of flow conveyed from the Spokane Valley to the SAWTP.
This could reduce Combined System Overflows (CSOs) in the central
portion of the City's conveyance system. Some segments of the
City's interceptor system would require replacement or the installation
of parallel sewers to convey future North Spokane flows to SAWTP.
Under this alternative a new 12-mgd plant would be constructed in the
south-central area of Spokane, within the city limits. This plant
would provide tertiary treatment and serve flows generated in the
Spokane Valley and the southern portion of the City's service area..
The County would retain its 10-mgd allocation in the SAWTP to
handle flows from North Spokane and a portion of the flows generated in
the Spokane Valley. The new plant would be jointly operated by the
City and County.
Because of the County's limited conveyance capacity in the City system,
all flows sent to the new plant would be pumped through a new forcemain.
The forcemain would be constructed through developed portions of the
City and would require the construction of pump stations.
This alternative is similar to Alternative 2, but would construct two
plants in the Mid-Valley area—a 5 mgd plant and a 7 mgd plant.
Both plants would provide tertiary treatment. The two smaller
plants would be located close to where wastewater is generated and where
the treated effluent could be sent to reuse applications. Flows
from the North Spokane area and a portion of the flows from the Spokane
Valley would continue to be sent to the SAWTP. The County would continue
to send 10 mgd to SAWTP.
Under this alternative, no wastewater treatment expansion would occur.
The County would continue to send all wastewater flows to the SAWTP
plant up to its maximum 10 mgd agreement. No new plant would be
constructed and the SAWTP would not be expanded. Under this
alternative, the County would reach its 10 mgd allocation by 2006 or
2007.
If the County takes no action to expand its wastewater treatment
facilities, the permit requirements for discharge to the Spokane River
could be violated and fines could be levied against the County. No
action could also result in a building moratorium and the imposition of
judicial control over the County’s wastewater treatment program.
In evaluating the alternatives for treatment plant facilities, Spokane
County applied the following criteria.
This criterion addressed the ability of an alternative to meet the
County’s near-term and long-term requirements for wastewater treatment
capacity. The near-term requirement relates to the ability to
implement the solution before 2007, when County flows are projected to
reach the capacity allocation in the SAWTP. The long-term
requirement relates to the alternative’s ability to provide a long-term
(50-year) solution.
This criterion considered the operational complexity of the alternative.
Since all alternatives would likely use similar treatment technologies,
the number of plants and major pumping facilities that must be
maintained primarily would affect the criterion. Fewer facility
requirements would result in a higher rating.
This criterion considered the extent and complexity of sewers and pump
stations that must be implemented.
Consideration was given to challenges associated with acquiring property
and permits. Generally, siting a North Spokane or In-City plant
was considered more challenging than siting a Mid-Valley plant.
Also, siting multiple new facilities resulted in a lower rating.
This factor relates to the County’s ability to implement the alternative
on its own, without relying on actions by other jurisdictions.
This criterion is significant given the need to implement additional
capacity by 2007.
This criterion addressed anticipated impacts to the receiving streams
and the potential for compliance with discharge permits.
Generally, alternatives that spread the location of effluent discharge
along receiving waters were rated higher because they would lessen
localized impacts. Alternatives with multiple plants were rated
lower because they would require compliance with more permits.
This factor considered the proximity of the treatment plants to
potential reuse opportunities.
This criterion addressed the environmental and community impacts of
building and operating wastewater facilities.
This factor compared total life cycle costs, including capital and
operating expenses.
This factor considered the risk associated with the economic assumptions
used in the analysis. Alternatives that relied on other
jurisdictions buying conveyance or treatment capacity from the County
were rated lower. Also, those alternatives that required other
jurisdictions to participate in the financing of projects were rated
lower.
The final action alternatives were compared against an array of
evaluation criteria using a modified "Consumer Reports" rating system.
The results are summarized in Table 4. The No Action Alternative
was not included in the evaluation because it does not involve any
action from the County.
Table 4.
Evaluation Criteria Results
Initially the County considered 13 wastewater treatment alternatives.
The 13 alternatives are variations of the four final alternatives
described above. The main components that vary in the alternatives are
the size of the treatment plants and the amount of wastewater flows that
would be sent to the SAWTP. In addition, the initial alternatives
considered construction of a 5 mgd plant in the North Spokane area to
handle flows from the North Spokane Service Area.
The size of treatment plants being considered under the initial
alternatives ranged from 3 and 4 mgd to 17 mgd. The size of the plants
varied depending on other components of the alternatives. Options for
the amount of wastewater flows to be sent to the SAWTP ranged from
discontinuing all flows from the County to the SAWTP, to increasing
County flows to the SAWTP to as much as 22 mgd.
Alternatives 2, 3, and 4 all initially included an option to construct a
small plant in North Spokane with discharge to the Little Spokane
River. This option was considered as a means to handle flows from the
North Spokane Service Area, and to beneficially recharge the Little
Spokane River. This option was eliminated from consideration because of
complications associated with discharging effluent to the Little Spokane
River, a limited number of suitable sites, and major costs associated
with changing the conveyance system.
In addition to the alternatives considered for treatment plant locations
and configurations, the County is considering different alternatives for
other components of wastewater treatment, including demand management,
effluent end use, and biosolids management. The alternatives are
presented below. These system components are intended to be used in
combination with the alternatives for treatment plants to improve
wastewater management in the County. It is likely that the alternatives
selected for these system components will be a combination of the
options presented below.
Demand management is the package of efforts designed to reduce the
quantity and/or strength of wastewater from the North Spokane and
Spokane Valley service areas. If demand management strategies are
successful, the size of treatment facilities could be reduced and costs
lowered. Spokane County already has important demand management
measures in place, including a ban on phosphorous-containing detergent,
an industrial pretreatment program, effective control of infiltration
and inflow, and a requirement that new construction or major remodels
use low volume plumbing. The County is considering the following
alternative measures to further reduce wastewater flows.
A water conservation alternative would include a public education
component to encourage people to use less water in daily activities.
The program would be continuous to help maintain conservation goals. A
second component of the water conservation element would be a plumbing
fixture replacement program to encourage replacement of old plumbing
fixtures. This component could be accomplished through public
education, economic incentives, and coordination with other agencies,
organizations, and businesses. A third component of the water
conservation element would be an inverted rate structure for public
water supply that would charge consumers a higher unit cost for any
water consumed above a base amount.
This alternative would reduce the amount of water that enters the sewer
lines by infiltration from groundwater or inflow from stormwater
runoff. One component of this alternative would be the elimination of
basement sump pump discharges to sewers. In areas of the County with
high groundwater tables, the County would use public education and
limited technical assistance to inform the public of the requirement to
eliminate basement sump pump flows from the sewer system. Another
component of the alternative would be the review of codes, inspection
and enforcement requirements to ensure that future construction would
produce minimal contributions of infiltration and inflow.
This alternative considers measures to further reduce the strength of
industrial wastewater flows. One component would be County review of
ordinances to determine if increased requirements to minimize industrial
wastewater quantities and strengths are needed. Another component of
this alternative would be to implement increased rates or surcharges for
industries or businesses discharging high strength wastes. The County
is also considering establishing requirements or incentives to encourage
industries to maximize water recycling and reuse within their
operations.
The County is considering the following alternatives for how treated
effluent is returned to the environment or beneficially reused. Under
all alternatives the County would comply with state and federal
guidelines and regulations for effluent reuse.
Under this alternative surface water discharge would continue for most
effluent generated by the system. Each of the five wastewater treatment
alternatives assumes that the primary effluent end use strategy will be
discharged to the Spokane River. Surface water discharge could be used
to augment minimum streamflows. The approach includes a relatively low
effluent conveyance cost, and simple effluent management requirements.
Disadvantages of this approach would be limited reuse of the effluent
and discharge of pollutants to the river during critical water quality
periods.
2.5.2.2
Effluent End Use Alternative 2 — Irrigation of Poplar Farms
Under this alternative hybrid poplars would be irrigated with treated
effluent. Hybrid poplars have a high water demand during summer months
and may produce revenue as pulp for paper or as a clear softwood.
Effluent for application would be treated to class C standards and
conveyed 7 to 20 miles to county-owned land.
This alternative would use treated effluent as an irrigation supply for
golf courses, school grounds, parks, cemeteries, highway medians,
industrial campuses, and other greenspaces. Irrigation use of effluent
would require construction of a distribution piping system and may
require storage facilities to hold water until needed. Irrigation of
lands overlying the Spokane Aquifer may require additional treatment to
reduce nitrate-nitrogen concentrations to acceptable levels for drinking
water. Use of effluent for irrigation would be limited to the summer
irrigation season. Effluent end use for irrigation could conserve
groundwater currently used for irrigation and reduce effluent discharge
to the river during the summer.
Another option for effluent end use would be the use of effluent to
irrigate agricultural lands. This alternative would have similar
advantages and disadvantages to the previous alternative. If dryland
areas were irrigated, there would be no reduction in groundwater
consumption. This alternative could benefit dryland agriculture by
allowing the production of higher value crops.
This alternative would provide treated wastewater to industries for use
as cooling water or in process applications. This alternative would
provide a year-round use for treated effluent and could conserve
groundwater currently used by industries. Industrial reuse may require
high treatment costs to meet user needs and more complicated discharge
permitting requirements. In addition, there is the risk that the
industry could relocate and/or change water requirements.
Treated effluent could be used to create constructed mitigation wetlands
or as a reliable water source to restore degraded wetlands. If the
wetlands are located along streams, the water could also be used to
augment streamflows after it is routed through the wetlands. The
advantages of this option include habitat creation, development of a
wetlands bank in the County to facilitate economic development, and the
potential to enhance stream discharge options. The disadvantages would
be a relatively low water demand, high land requirements for wetland
construction, and the potential for adverse public perception of
wastewater use over the aquifer.
Effluent that was treated to a very high level could be used to recharge
the groundwater supply. This could be accomplished through surface
percolation (spreading basins) or direct injection wells. The water
recharged to the aquifer could be withdrawn and used for any permitted
use. The advantages of groundwater recharge are maximum use of the
effluent as a water resource, minimal discharge to streams, and recharge
of the aquifer to provide an adequate water supply for present and
future needs. The major disadvantages are the high cost of treatment to
drinking water standards, the potential adverse public perception of
effluent discharge to the aquifer, and regulatory requirements.
Biosolids are the residual materials from wastewater treatment. They
contain organic matter and plant nutrients such as nitrogen and
phosphorous. Biosolids can make good soil amendments, but the quality
must be managed to minimize the presence of trace toxic materials and
disease-causing organisms. Currently the biosolids produced at SAWTP
are treated to Class B standards to destroy disease causing
microorganisms, to reduce the organic content, and to reduce the water
content. The treated biosolids are trucked to agricultural lands west
of Spokane and used as soil amendments. The following options are being
considered for managing biosolids.
This approach would be similar to the practice currently used at SAWTP,
and is assumed to be the primary biosolids strategy for each of the five
wastewater treatment alternatives. Biosolids would be digested,
dewatered and transported for land application. The sites for land
application could be agricultural land or disturbed mining areas. The
advantages of this alternative are beneficial reuse of the biosolids,
relative low operational cost, well-established technology, and good
demand. The disadvantages would be limited end-uses for biosolids and
the potential that future regulations could require higher levels of
treatment.
Under this alternative, the biosolids would be treated to higher Class A
standards with a high-temperature treatment process prior to
dewatering. Biosolids treated to higher standards have greater
opportunities for end use, greater acceptance by potential users, less
space requirements for treatment facilities, and less susceptibility to
future regulatory change. The major disadvantages would be higher
energy costs for treatment, operation of a more complex treatment
process, and a greater need for odor control.
Under this alternative, Class A standards would be achieved by
composting the Class B biosolids. The end product is well accepted by
end users. The treatment facilities are low technology and fairly easy
to operate. Disadvantages of composting are that it is relatively
expensive, requires land areas and a higher level of dewatering than
land application, and requires significant odor control measures.
This alternative would construct no biosolids treatment facilities at
the new treatment plant sites (Alternatives 2, 3, or 4). All biosolids
would be conveyed to the SAWTP for treatment. The biosolids could be
conveyed by the interceptor pipe system or a separate pipeline. This
alternative would require smaller plant sites for the new plants and
would consolidate all biosolids handling in one location. The major
disadvantages of this approach are increased liquid treatment costs at
SAWTP, possible spillage of solids during CSO events if the solids are
returned to the interceptor or high conveyance costs of constructing
dedicated pipelines. Under this alternative, the County would be
dependent on the City for biosolids treatment and disposal and an
agreement between the County and City would be required to implement the
proposal.
This alternative would incinerate dewatered biosolids at the regional
solid waste incinerator. The advantages of this approach would be a
high level of volume reduction and multiple use of a regional waste
management facility. The disadvantages would be air quality concerns
and permitting issues, high energy costs, potential compatibility issues
with the solid waste system, and failure to beneficially use the
biosolids.
Under this alternative, the County would contract with a private vendor
to manage the biosolids, with the vendor hauling the material to a
processing site. This approach is used in some places in the region,
including ECO composting in Missoula, Montana. The advantages of this
approach are lower capital costs, reduced space requirements for
treatment facilities, and simpler siting of new treatment plants. The
disadvantages would be high transportation costs, potentially higher
operating costs, and increased risk through dependency on a private
entity.
3.0
Impacts of alternatives and mitigation
This chapter assesses the impacts of the proposed alternatives for
expansion of wastewater treatment facilities in Spokane County. The
impacts of the alternatives for other system components are described in
Chapter 4. Based on results of the public scoping process, the
assessment includes a discussion of impacts associated with the
following elements of the environment: land use, water resources,
environmental health, plants and animals, energy and natural resources,
air quality, and transportation. This chapter describes the affected
environment, construction and operation impacts, and appropriate
mitigation measures for each of these elements.
This section describes the land use effects
associated with construction and operation of wastewater treatment
facilities, and the project's consistency with adopted land use plans
and zoning codes. Relevant land use regulations for Spokane County and
the City of Spokane are described, including Comprehensive Plans, Zoning
Codes, and Shoreline Programs.
The portions of Spokane County being considered for wastewater treatment
facilities are designated in a variety of land use classifications,
including residential, commercial, industrial, mixed use, rural
conservation, small track agriculture, and mineral land. Most of the
area near the Spokane city limits and near the Spokane River has been
developed as residential, commercial, or industrial. Areas further east
and further from the river are less developed and are generally rural or
agricultural. The area within the city limits under consideration for a
new wastewater treatment plant has been developed as residential,
commercial, or industrial.
The Washington Growth Management Act (GMA) of 1990 requires that cities
and counties prepare comprehensive plans that conform with GMA goals and
urban growth area designations, and with population projections
developed under the GMA planning process. In August 2001 Spokane County
adopted a revised Comprehensive Plan based on revisions to the 1994
document, Countywide Planning Policies. Spokane County prepared
a draft and final Environmental Impact Statement on the Recommended
Comprehensive Plan. The revised Comprehensive Plan contains
policies for capital facilities and utilities, including wastewater
treatment facilities.
The City of Spokane adopted a revised Comprehensive Plan on May
21, 2001 (Johnston, 2001). A Draft Comprehensive Plan and Draft
Environmental Impact Statement (City of Spokane, 2000) and a
Final Environmental Impact Statement for the Recommended Comprehensive
Plan (City of Spokane, 2001a) were prepared in support of the
revision process. The revised Comprehensive Plan contains
policies for capital facilities and utilities, including wastewater
treatment facilities.
The GMA requires that a comprehensive plan or development regulation
must allow for the siting of an essential public facility. The GMA
directs counties to "provide for a cooperative interjurisdictional
approach to siting essential public facilities of a countywide, regional
or statewide nature consistent with the Countywide Planning Policies" (WAC
365-195-340.3b). In 1996, the County approved the Growth Management
Essential Public Facilities Technical Committee Report (Spokane
County, 1996). The report was submitted to all Spokane County
jurisdictions for inclusion in their comprehensive plans. The report
includes a Model Siting Process, an Interjurisdictional Consistency
Review Process, and an inventory of existing essential facilities.
Sewage treatment facilities are included as an essential public facility
of a regional/countywide nature. The report is included as part of the
2001 Recommended Comprehensive Plan.
The Model Siting Process includes the following steps:
·
Step One: Identify the proposed project as an
essential public facility.
·
Step Two: Classify the facility as having a
statewide, regional/countywide, or local significance.
·
Step Three: Provide early notification and
involvement of affected citizens and jurisdictions allowing for
opportunities to comment on the proposal. The nature of the factors
making the facility difficult to site should be considered when
determining the appropriate level and type of citizen participation in
the siting process.
·
Step Four: Applicants for statewide and
regional/countywide significant facilities should provide an analysis of
alternative sites considered for the proposed facility.
·
Step Five: The proposed facility should be
reviewed for impacts of the facility on regional growth planning
concepts such as the urban nature of the facility, existing urban growth
near the facility site, compatibility of urban growth with the facility,
compatibility of facility siting with respect to Urban Growth Area
boundaries, urban sprawl, economic development, and affordable housing.
·
Step Six: Proposed essential public facilities
should be reviewed for site development criteria including the time
required for construction, property acquisition, control of onsite and
offsite impacts during construction, and expediting and streamlining
necessary government approvals and permits if all other criteria have
been met.
·
Step Seven: The proposed facility should be
reviewed to determine if the financial impact on the jurisdiction can be
reduced or avoided.
The siting of a new wastewater treatment plant, if recommended by the
Board of County Commissioners, will be consistent with this process.
The Spokane County Wastewater Facilities Plan is consistent with the
recently adopted Spokane County Comprehensive Plan. The County’s
Division of Planning and Utilities Division worked together closely to
develop consistent projections for population, commercial and industrial
growth within the County’s Sewer Service Area. The estimates of
population served by the County’s wastewater treatment facilities are
based on population growth projections and include extension of service
to existing populations in the County not currently served by sewers.
These areas have been identified for future connection to the County
sewer system through the Septic Tank Elimination Program to protect
water quality in the Spokane Aquifer.
Zoning Ordinances for both Spokane County and the City of Spokane direct
development in the area (Spokane County, 1998). Spokane County's Zoning
Ordinance (Chapter 14) includes wastewater treatment facilities in its
definitions of a Public Utility Distribution Facility and a Public
Utility Transmission Facility. Both distribution and transmission
facilities are permitted in all residential zones. In business,
industrial, mining, and agricultural zones, distribution facilities are
permitted. Transmission facilities are permitted subject to the
following conditions:
·
The utility company shall secure the necessary property or
right-of-way to assure the proper construction, continued maintenance,
and general safety to the properties adjoining the public utility
transmission facility;
·
The facilities shall be compatible with the surrounding
uses either by distance, landscaping, buffering, or design, as
determined by the Zoning Administrator; and
·
The height of the structure above ground does not exceed
125 feet.
The City of Spokane allows sewage treatment plants in all zones by
special permit. According to Article IV: Special Uses, subsection
13.19.310: Uses by Special Permit in Any Zone, of the Spokane Municipal
Code–Land Use (City of Spokane, 2001), a special permit can be granted
by the hearing examiner in any zone subject to conditions and standards
as deemed necessary by the examiner.
Spokane County's Shoreline Program was adopted in 1974 (Spokane County,
1974). The program regulates development of shorelines within 200 feet
of the ordinary high water mark of streams with flows greater than 20
cubic feet per second (cfs), and lakes, impoundments, and reservoirs
larger than 20 acres. A Shoreline Management Substantial Development
Permit is required for any development within these shoreline areas.
Shorelines in Spokane County are classified in five categories:
Natural, Pastoral, Conservancy, Rural, and Urban. Spokane County's
Shoreline Program permits wastewater treatment facilities in all
shoreline areas except Natural Areas. Shoreline designations along the
Spokane River east of the city limits are either Conservancy or
Pastoral. Wastewater treatment and disposal facilities permitted in
shoreline areas must meet the following conditions:
·
Compelling reasons exist for the specific site selection;
·
Mitigation measures would prevent these facilities from
degrading the shoreline area with odors, noise, and visual detraction;
·
Subsurface disposal of wastewater would be prevented;
·
Facilities would not obstruct or impede the flow of
floodwaters; and
·
Facilities would be designed so that, if flooding
occurred, they would be protected from damage and would continue to
function.
The City of Spokane's Shoreline Master Program was adopted in 1975 and
amended in 1977. The program sets goals and policies, regulates
activities, and authorizes a permit system in a 200-foot shoreline area
adjacent to the Spokane River and Latah Creek in compliance with the
State Shoreline Management Act. In 1982 the City Council approved a
Supplement to the Master Program containing revised use regulations and
administrative procedures (City of Spokane, 1982). Siting of wastewater
treatment plants is allowed in shoreline zones as a conditional use.
During construction, nearby residents and businesses may experience
temporary construction-related impacts, such as increased noise, dust,
and construction vehicle traffic. Traffic may be temporarily rerouted.
These impacts would be temporary and would cease upon completion of
construction.
Direct Land Use Impacts.
Development of treatment plant facilities may require conversion
of existing land uses to a utility use. In addition, conversion of
private property to a public use would remove this land from the tax
rolls, and could have minor impacts on Spokane County's revenue stream.
Under Alternative 5, No Action, a moratorium on building would likely
occur. Design of the wastewater treatment facility would likely
incorporate architectural treatment, landscaping, and/or buffering to
minimize adverse impacts on the adjacent neighborhood, and may raise
land use compatibility issues in some areas. More information on
impacts at specific sites will be available during the next phase of the
wastewater planning process, after the County has selected its preferred
system alternative.
Little or no effect on property values is expected as a result of
Alternative 1 because this alternative is the expansion of an existing
treatment plant. The potential to impact property values is greater for
Alternatives 2 through 4 since they include the siting of one or more
new treatment plants. The extent of impact, if any, will depend on the
location selected for a new plant. Additional information about
potential plant locations will be developed following selection of a
preferred alternative by the Board of County Commissioners.
The following mitigation measures could be implemented to relieve
construction impacts on residences and businesses near the treatment
facility site:
·
Develop a traffic control plan to ensure continued vehicular
access on streets in the project vicinity.
·
Restrict construction to daylight hours of weekdays to reduce
noise impacts on nearby residents; in addition, muffler systems on heavy
construction equipment should be kept in good working order to ensure
maximum noise attenuation.
·
Employ approved dust control measures during the construction
phase. This could include spraying areas of exposed soils with water
and/or palliatives as necessary to reduce visible dust emissions. Dust
emissions from soil transport should be reduced by covering loads,
wetting dry soil, and washing of construction vehicle wheels.
Construction of wastewater treatment facilities is permitted under
County land use and shoreline regulations and would not require any
rezoning or comprehensive plan amendments. If the plant were located
within the Spokane city limits, it would require a Special Permit under
City zoning laws and a Conditional Use Permit if located in the
shoreline zone. Project features such as odor control devices to reduce
off-site odor impacts, visual screening of the facility with vegetation,
and architectural treatment consistent with nearby structures or with a
community-supported design theme would assist in maintaining
compatibility with surrounding uses. If public amenities are included
within the facility's grounds (e.g., park-like use areas, trails, etc.),
the local neighborhood could perceive the addition of public open space
or recreation areas as a beneficial impact.
This section describes the surface and
groundwater resources of the project area and the existing water quality
of those resources. Surface and groundwater are discussed separately,
but the two experience a high degree of hydraulic connectivity in the
Spokane area. Relevant federal, state, and local regulations are
presented. The regulations are presented first to establish the
framework for the following discussions. Impacts of each of the
proposed alternatives on water resources and water quality are
discussed.
Relevant Federal, State, and Local
Regulations. There are numerous federal, state, and local
regulations that apply to water management in the Spokane area. Those
most relevant to construction of new wastewater treatment facilities are
discussed here.
Clean Water Act.
The federal Clean Water Act (CWA) establishes the federal authority to
set water quality and effluent standards to protect the nation's
waters. The CWA makes it unlawful to discharge any pollutant from a
point source without a National Pollution Discharge Elimination Permit (NPDES).
The CWA is administered by the federal Environmental Protection Agency
(EPA), but the authority for permitting, administration, and enforcement
of provisions of the CWA has been delegated to most states. The state
of Washington has received EPA approval to administer the CWA provisions
through the Department of Ecology (Ecology). Ecology issues NPDES
permits that define limits of discharges, and monitoring and reporting
requirements.
Section 303(d) of the CWA requires each state to identify its polluted
water bodies and submit the list to EPA every four years. The 303(d)
list identifies those water bodies that are water quality limited, or
those water bodies that fall short of state surface water quality
standards. The CWA requires that states set priorities for cleanup of
the 303(d) listed waters and establish cleanup plans. One aspect of the
cleanup process is the establishment of Total Maximum Daily Load (TMDL).
A TMDL is a calculation of the maximum amount of a pollutant that a
water body can receive and still meet water quality standards, and an
allocation of portions of that maximum amount to the sources that
discharge that pollutant. A TMDL is established for each pollutant that
exceeds state standards.
Safe Drinking Water Act.
The federal Safe Drinking Water Act (SDWA) of 1974 establishes standards
for drinking water supplies, including groundwater supplies.
Groundwater aquifers that serve as drinking water supplies can be
protected by a "sole source" aquifer designation. A sole source aquifer
is defined as an aquifer that supplies at least 50 percent of the
drinking water to the area overlying the aquifer and in an area where
physical, legal, or economic considerations limit the reliability of an
alternative drinking water source (U.S. EPA, 2001). The sole source
designation is intended to protect such aquifers from contamination.
The primary mechanism for protection is the requirement that all
proposed federal financially-assisted projects that have the potential
to contaminate the aquifer be reviewed by the EPA. Proposed projects
that do not have any federal funding are not required to be reviewed by
EPA. The Safe Drinking Water Act was amended in 1996 to emphasize
protection of drinking water sources through comprehensive watershed
planning. The amendments require states to develop a Source Water
Assessment Plan that delineates source water protection areas,
inventories contaminants in these areas and assesses the water system's
vulnerability to these contaminants. Information from the assessments
must be made available to the public.
State Surface Water Quality Standards.
The Washington Department of Ecology classifies streams by water quality
based on definitions in WAC 173-201A (Water Quality Standards for
Surface Waters of the State of Washington). The Middle Spokane River
from RM 58.0 (Nine Mile Bridge) to the Idaho State line is designated as
a Class A (excellent) stream. Long Lake from Long Lake Dam to Nine Mile
Bridge is classified as "Lake Class," and the Little Spokane River is
classified as Class A. The characteristic uses for these
classifications are water supply, stock watering, fish and shellfish,
wildlife habitat, recreation, and commerce and navigation. Water
quality in the rivers must comply with the water quality standards
specified in WAC 173-201A.
State Groundwater Quality Standards.
The Groundwater Quality Standards (WAC 170-200) are designed to protect
the quality of all groundwater in the state in the saturated zone. The
standards include three mechanisms to maintain high groundwater
quality. Prior to discharge into any of the state’s waters, all known,
available and reasonable methods of prevention, control, and treatment (AKART)
must be employed. The standards include an antidegradation polity to
protect background water quality and to prevent degradation. The
standards also include criteria for the maximum concentration of
specific contaminants. The criteria are based on human health and
welfare standards.
Minimum Flows.
The Department of Ecology is authorized to establish minimum streamflows
on streams and rivers in the state. These minimum flows are established
to protect fish and wildlife, recreation, water quality, navigation, and
aesthetics. The minimum flows are established by administrative rule.
Ecology may not issue water rights that would reduce streamflows below
those established for minimum flows, and Ecology may take enforcement
actions against water users who withdraw water below the established
minimum flows.
Watershed Planning.
In 1998, the state established a watershed planning process for
designated Water Resource Inventory Areas (WRIAs) in the state (RCW
90.82). The authorizing legislation was Senate Bill 2514, and the
process is frequently referred to as SB 2514 planning. The legislation
provides grant funding for local governments to develop watershed plans
for managing water resources and protecting existing water rights. Each
watershed unit must plan for water quantity issues and may opt to plan
for water quality, fish habitat, and instream flows.
Water Quality Management Plan.
There are several groundwater protection programs in place in the
Spokane area. The Water Quality Management Plan is a program managed
jointly by the City of Spokane and Spokane County. The Plan, adopted in
1979, is intended to eliminate the major sources of contamination to the
aquifer and restore its water quality. Tools used to achieve these
goals include 1) zoning ordinances and development restrictions, 2) a
wastewater management plan, 3) stormwater management, 4) a critical
materials ordinance, 5) and public education. The program has
successfully stopped the degradation of water quality in public water
supply wells. The success is largely attributed to the reduction in
individual septic systems located over the aquifer.
Major Surface Water Bodies.
The major surface water body in the Spokane area is the Spokane River,
which flows through the City of Spokane. The major tributaries of the
Spokane River are the Little Spokane River from the north and Latah
(Hangman) Creek from the south.
Spokane River.
The source of the Spokane River is Lake Coeur d'Alene in Idaho. The
river is approximately 111 miles long and drains an area of 6,580 square
miles including the Coeur d’Alene and St. Joe Rivers. The river flows
in a westerly direction from the lake through the City of Spokane (See
Figure 4). Below the city, the river is dammed by Long Lake Dam to form
Long Lake. Below Long Lake, the river flows into the Columbia River at
Franklin D. Roosevelt Lake, which backs up into the Spokane River.
There are five hydroelectric dams on the Spokane River between the Idaho
border (RM 96) and Lake Roosevelt. These dams are Upriver Dam (RM
79.9), Division Street Diversion Dam (RM 74.4), Monroe Street Dam (RM
73.9), Nine-Mile Dam (RM 57.6), and Long Lake Dam (RM 33.9). Post Falls
Dam in Idaho (RM 100.8) influences the hydrology of the Spokane River
through the project area. All of the dams but Long Lake Dam are
run-of-river dams, not storage dams. Run-of-river dams back up only
enough water to establish a constant head for operation of the
hydroelectric turbines.
The Spokane River experiences seasonal streamflow fluctuations, with
flows peaking during spring snow melt and declining in late summer.
Typical streamflows range from less than 2,000 cubic feet per second
(cfs) in August to 20,000 cfs in May or June (Spokane County, 2001c).
Historically peak flows have exceeded 45,000 cfs (USGS, 2001). Low
streamflows are a problem in summer and affect water quality. During
low flows, streamflows are regulated by operation of the Post Falls Dam,
operated by Avista Utilities. Avista's agreement with the State of
Idaho to maintain the level of Lake Coeur d'Alene limits the amount of
flow released to the Spokane River. Ecology has recommended minimum
flows for the Spokane River based on Washington Department of Fish and
Wildlife recommendations, but they have not been adopted as an
administrative rule. The recommended flows are 2,000 cfs at the Spokane
gage.
Little Spokane River.
The Little Spokane River flows into the Spokane River at Long
Lake, approximately 5 miles north of the Spokane city limits. The
Little Spokane is headwatered in Pend Oreille County near Newport. It
is joined by the West Fork just south of the Spokane County border. The
lower segment of the Little Spokane River is designated as a state
scenic river. This designation is less strict than a federal Wild and
Scenic River designation, but still places restrictions on activities
near the designated segment, particularly for the location of dangerous
waste management facilities or the discharge of any hazardous
substances.
Streamflows on the Little Spokane are measured at the U.S. Geological
Survey (USGS) gage at Dartford. Streamflows typically range from 300
cfs to 700 cfs. Summer flows on the Little Spokane are supplied almost
completely by groundwater discharges to the river. Summer flows in the
river have been declining since the 1950s, due to surface and
groundwater withdrawals and diversions (Washington Department of
Ecology, 1995). In 1975, Ecology closed the Little Spokane Basin to
further water appropriations because of concerns about water
availability and developed a management plan for the river. All water
rights issued since then have been conditioned to specific base flows.
A base flow of 115 cfs from July 1 to September 15 at the Dartford gage
is established by administrative rule in WAC 173-555. According to
Ecology, streamflows at the Dartford gage do not meet minimum flow
requirements approximately 15 percent of the time (Washington Department
of Ecology, 1995). Streamflows at the downstream Rutter Parkway gage
are significantly higher because of recharge from the Spokane Aquifer.
Figure 4. Spokane Area Water Resources
Latah (Hangman) Creek.
Latah Creek flows into the Spokane River on the west side of the city.
The creek originates in Idaho and flows northwest to the Spokane River.
Flows on Latah Creek fluctuate between a low of 30 cfs in summer to
peaks of 2,000 cfs in winter.
Permeable soils and the glacial history of the area have created
numerous groundwater aquifers in the area (See Figure 5). The largest
of these aquifers is the Spokane Valley-Rathdrum Prairie Aquifer
(Spokane Aquifer), which extends from Lake Pend Oreille through the
Spokane Valley. Other aquifers in the area are the Deer Park Aquifer,
the Little Spokane Aquifer, the Green Bluff, Peone Prairie, and
Orchard-Pleasant Prairie Aquifers, and the East Columbia Plateau
Aquifer. The latter includes the West Plains Aquifer.
The Spokane Aquifer is the primary source of
drinking water for more than 400,000 people in Idaho and Washington. In
1978 the Environmental Protection Agency (EPA) designated the Spokane
Valley-Rathdrum Aquifer as a "sole source" aquifer under authority of
the Safe Drinking Water Act.
Connectivity. The
Spokane-Rathdrum Prairie Aquifer is hydraulically connected to the
Spokane and Little Spokane Rivers. At times the rivers gain flow from
the aquifer; at other times the aquifer gains flow from the rivers (see
Figure 6). The hydraulic connectivity significantly affects streamflows
and the level of the aquifer and can affect water quality of both the
aquifer and the rivers. Connectivity is a key element in the evaluation
of potential water rights for withdrawals from the Spokane Aquifer.
The Spokane River loses large quantities of water to the aquifer in the
Spokane Valley. Recent studies indicate that more than 140 cfs is lost
to the aquifer between Post Falls Dam and Barker Road. On the Little
Spokane River, groundwater inflow to the river represents nearly the
entire discharge to the river above the Dartford gaging station. Below
the Dartford station, streamflow increases due to groundwater inflow
from the Spokane Valley-Rathdrum Aquifer.
Hydraulic connectivity is most significant during summer low-flow
periods. During summer it is estimated that up to 80 percent of
streamflow in the Spokane River is aquifer discharge, whereas in the
winter only 20 percent of streamflow is aquifer discharge (Miller,
1996). There is still much uncertainty about the hydrology of the
region and the amount of water exchange that occurs between the rivers
and the aquifer.
Floodplains. The Federal
Emergency Management Agency (FEMA) maps flood prone areas for cities and
counties based on calculation of the 100-year flood--a flood with a 1
percent statistical probability of occurring in any given year. Major
floodplains in the Spokane area are located along the shores of lakes,
the Spokane River, and Little Spokane River. Within the planning area
for the wastewater treatment plant, floodplain areas are limited to the
area immediately adjacent to the Spokane River.
Water quality issues in the Spokane area involve both surface and
groundwater resources. Several segments of the Spokane and Little
Spokane Rivers have been placed on the federal Clean Water Act Section
303(d) list of impaired water bodies. Because the Spokane Aquifer is
unconfined, it can be easily contaminated. Any contamination poses a
threat to the sole source of drinking water for the region.
Water bodies are included on the 303(d) list because water quality does
not meet state standards and technology based controls are inadequate to
achieve those standards. The Department of Ecology's (Ecology) 303(d)
list for the Spokane River includes the constituents arsenic, cadmium,
chromium, dissolved oxygen, lead, PCBs, sediment bioassay, and zinc.
Cadmium, lead, and zinc concentrations often exceed state water quality
standards at the state border. The source of these contaminants is
attributed to the discharge of heavy metals at the Bunker Hill Superfund
site on the South Fork Coeur d'Alene River, which discharges to Lake
Coeur d'Alene. Much of the metal loading reaching Washington is from
the resuspension of sediment deposited outside the designated Bunker
Hill Superfund site. For 303(d) water bodies, the state must develop
Total Maximum Daily Loads (TMDL) or maximum limits on the amounts of
pollutants that can be discharged to a water body and allow that water
body to meet water quality standards. Ecology has established TMDLs on
the Spokane River for phosphorous and metals (cadmium, lead, and zinc)
and is considering a TMDL for dissolved oxygen in Long Lake and the
Spokane River. Segments of the Little Spokane River have been placed on
the 303(d) impaired list for the constituents fecal coliform, PCBs, pH,
and temperature. No TMDLs have been established for the Little Spokane
River.
Figure 5. Spokane Area Aquifers
Figure 6. Hydraulic Connectivity
Because of its sole source aquifer listing, water quality in the Spokane
Aquifer has been monitored for over 20 years. During this time, aquifer
water quality has generally been good to excellent. There have been
less than 50 violations of drinking water standards. During the mid
1980s, water quality declined slightly in terms of inorganic indicators
like nitrate-nitrogen and chloride. The decline was attributed to
increased development and associated septic tanks and drainfields.
These water quality indicators improved steadily in the late 1980s and
1990s as sewer construction increased to replace septic tanks. Septic
tanks continue to be a contributor to local declines in water quality.
Other potential sources of groundwater contamination in the region have
been identified and include stormwater injection through dry wells;
chemical storage, transport, and accidental spills; improperly abandoned
wells; leakage from underground pipelines and sewers; over-application
and spillage of fertilizers; application of road de-icing compounds;
leakage from above ground or underground fuel storage tanks and
pipelines; improper waste disposal in excavations; sanitary landfills;
and gravel pit mining.
Watershed Planning. Three
of four WRIAs covering the Spokane River Basin are involved in watershed
planning. Watershed planning for the Middle Spokane and Little Spokane
Rivers (WRIAs 55 and 57) is being conducted jointly. Watershed
assessment and development of a water budget for the combined basins
has begun. Water quality, an optional planning component, is also being
addressed in the watershed planning process for WRIAs 55 and 57. Water
quality is being evaluated as it relates to flows.
Latah Creek is located in WRIA 56. The Latah Creek Planning Unit has
completed the Phase 2 work plan and watershed assessment began in early
2001. The Latah Creek Planning Unit has accepted the optional
components of water quality, instream flow, and fish habitat. No lead
agency has been established for WRIA 54, the Lower Spokane River.
Proposed Water and Effluent Quality
Standards. A preliminary assessment has been made of likely
effluent quality requirements for discharge of wastewater to the Spokane
River based on state water quality standards and seasonal
characteristics of the river (Spokane County, 2001c). These potential
requirements are shown in Table 5. Discharge requirements will be
established by Ecology during the NPDES permitting process. The
permitting process requires the County to demonstrate that effluent
discharge will allow the receiving waters to meet water quality
standards.
The summer low-flow period is the most critical for water quality;
therefore, Ecology typically establishes seasonal permit limits for
wastewater discharges. The more stringent requirements are in summer.
The potential discharge requirements shown in Table 5 reflect the need
for more strict requirements in summer.
Table 5. Anticipated Effluent Quality
Requirements for New Surface Water Discharges for the Spokane River
(Monthly Average Values Unless Noted Otherwise).
|
Parameter |
Summer |
Winter |
|
BOD (mg/L)1 |
10-20 |
30 |
|
Total Suspended Solids (mg/L) |
30 |
30 |
|
Ammonia-Nitrogen (mg/L)1,2 |
1-2 |
4-8 |
|
Total Nitrogen (mg/L) |
No limit |
No limit |
|
Total Phosphorous (mg/L)1,3 |
0.3-0.6 |
No limit |
|
Dissolved Oxygen (mg/L)1 |
>6.0 |
No limit |
|
Fecal Coliform (cfu/100 mL) |
200 |
200 |
|
Chlorine Residual (µg/L)2 |
~8 |
~ 8 |
|
pH (s.u.)4 |
6.0-7.8 |
6.0-7.8 |
|
Lead (µg/L)5 |
~ 2 |
~2 |
|
Zinc (µg/L)5 |
~ 60 |
~ 60 |
|
Cadmium (µg/L)5 |
~ 0.2 |
~ 0.2 |
SOURCE: Draft Wastewater Facility
Plan; Spokane County, 2001b.
1 Required value will be defined by
dissolved oxygen TMDL process.
2 Required value will be defined by
mixing zone study for toxicity.
3 Required value will be defined
through negotiation with Phosphorous TAC.
4 Instantaneous value.
5
Required value will be defined based on monitoring of actual
effluent metals concentration.
3.2.2.1
Construction
All alternatives except the No Action Alternative would have similar
construction related impacts to water resources. Alternative 5, No
Action, would require no construction and thus would have no
construction related impacts. Alternative 1 would require construction
near the river to expand the existing SAWTP. Alternatives 2, 3, and 4
would require construction of new plants on new sites. Construction
impacts to water resources at these location(s) would depend on the
proximity of the sites to surface water bodies. If the plant location(s)
are near surface water bodies, construction could generate increased
runoff and sedimentation that could affect water quality. It is likely
that construction of a new outfall for discharges to the river will be
required for Alternatives 2, 3, and 4. New outfall construction will
require in-water work, and could affect water quality during
construction. Because of the depth to groundwater, it is unlikely that
construction of the new treatment plants or expansion of the SAWTP would
require dewatering.
Alternatives 1 through 4 would require the construction of additional
conveyance facilities. Alternative 1 will require the largest amount of
construction to install an 8-mile forcemain and two pumping stations
through an urban area. Conveyance facilities for Alternatives 2, 3, and
4 will also involve forcemain and pumping station construction, but on a
smaller scale than Alternative 1. Runoff from construction of these
facilities could impact nearby water bodies. Conveyance construction for
Alternative 1 will require a crossing of the Spokane River. The river
crossing work could require in water construction.
3.2.2.2
Operation
The wastewater treatment facilities proposed under all the alternatives
could generate operational impacts on nearby water bodies. Expansion of
the SAWTP under Alternative 1 and construction of new treatment plants
under Alternatives 2, 3, and 4 would increase the amount of effluent
discharged to the Spokane River. The County is considering alternatives
that would reduce the amount of effluent discharged (See Section 3.9.2);
however, the majority of effluent will be discharged to the Spokane
River. For all alternatives, effluent discharges would meet the
standards of the NPDES permit negotiated with the Department of
Ecology.
It is anticipated that effluent quality requirements will be based on
the requirements presented in Table 5, but will be refined based on the
exact location of the discharge, results of mixing zone studies,
effluent concentrations of metals, results of a dissolved oxygen TMDL
Study, and negotiations with the Phosphorous Technical Advisory
Committee. Preliminary modeling indicates that near-field
dissolved oxygen (DO) levels will be 0.2 mg/L or less. This level of
impact is allowable in stretches of the river where natural conditions
prevent instream water quality from being met. The stretch of river
being considered for the discharge point has a naturally low level of DO
from groundwater recharge. The effluent discharge will not violate
temperature criteria. The water quality criteria for lead, cadmium, and
zinc are already exceeded on the Spokane River. The County anticipates
receiving a performance based effluent limit to avoid worsening the
condition. In order to ensure that the metals concentrations in the
effluent are low, the County will focus on identifying industrial
discharge sources and requiring aggressive pretreatment to remove metals
before discharges reach the County's waste stream. The new plant will
not use chlorine disinfection; therefore, there will be no chlorine
toxicity problems. Modeling indicates that the ammonia-nitrogen
concentration will be below ammonia toxicity criteria. The effluent is
not expected to contain PCBs since the City of Spokane has not detected
PCBs in the effluent from the SAWTP. The assessment of far-field
impacts will require more detailed modeling than can be performed at
this time; however, it is anticipated that the new plant will produce
low concentrations of DO consuming constituents such as biochemical
oxygen demand (BOD) and ammonia. The effluent will also contain low
levels of phosphorous which can lead to primary production activity
downstream.
Alternative 1, expansion of the SAWTP, would concentrate effluent at one
location on the river and could make meeting water quality standards
difficult. Alternatives 2, 3, and 4 would allow greater dispersal of
effluent discharges. Alternative 4 would provide the greatest effluent
dispersal with the use of two smaller plants. Alternative 2 would
provide greater dispersal than Alternative 3 because it would be located
at a greater distance from the SAWTP and effluent would be discharged in
the section of the river below Upriver Dam. Discharge to the reach
below Upriver Dam provides several advantages over other discharge
points on the river. The reach is located on a gaining stretch of the
river and would reduce the potential for discharge to the aquifer or
migration of effluent into the aquifer. This reach of the river
provides good separation from the SAWTP discharge. The reach is located
downstream of the discharge points for Inland Empire Paper, Kaiser, and
Liberty Lake, and would require consideration of those discharges in
NPDES negotiations.
Under Alternative 1, the SAWTP site is projected to have adequate space
for expansion to handle predicted wastewater flows through 2025. The
SAWTP will be expanded to 65 mgd in the 2020 horizon. The site would
then be at maximum capacity and could not be expanded on site to handle
additional flows from the City or County.
Groundwater quality would improve under all the action alternatives.
Currently, wastewater is leaching into the aquifer though septic tanks.
The County’s Septic Tank Elimination Program requires increased
treatment plant capacity to handle the increased volume of flows
generated by new connection to the wastewater treatment system.
Alternatives 1 through 4 all provide expanded capacity and would allow
the County to continue to improve groundwater quality through its Septic
Tank Elimination Program.
None of the alternatives are expected to have significant impacts on
water quantity in the Spokane River. All the action alternatives would
increase effluent discharges to the Spokane River by 34 cfs in 2025 and
42 cfs in 2050. This is approximately 3 percent of the average summer
flow of 1,400 cfs and an even smaller percent of winter peak flows. The
increased discharges are not expected to affect the hydrology of the
river.
Construction in a flood-prone area could subject the treatment plant to
damage that could make the plant inoperable during a flood event. The
treatment plant structures could also impede floodwaters and block flow,
increasing flood damage.
Water quality impacts would be unacceptable under Alternative 5, No
Action. If no new treatment plant were constructed, the county would
exceed its 10 mgd capacity at the SAWTP by 2007. The County would be
unable to provide adequate capacity for projected growth within the
planning area. This could result in building moratoriums, fines for
violation of water quality standards, and possible imposition of
judicial control to regulate water quality. The County would also be
unable to continue its Septic Tank Elimination Program. This could
result in declines in groundwater quality of the Spokane Aquifer.
3.2.3.1
Construction
Construction of the wastewater treatment facilities could lead to
increased erosion and sedimentation that could impact adjacent water
bodies. Erosion and sedimentation control measures suitable for the
selected site would be included as part of project design and
construction to minimize sedimentation. Spokane County will require
that a comprehensive erosion and sediment control plan be developed
prior to construction. At a minimum the plan would include elements for
site stabilization, slope protection, drainageway protection, and
sediment retention. All construction activity would be required to use
best management practices to minimize erosion and sedimentation
impacts. The project would also be required to comply with conditions
of the NPDES general permit for construction issued by Ecology. A spill
control plan to prevent fuel, chemical, or other pollutant spills from
reaching any surface water bodies or seeping into groundwater will be
developed. For any in water work, including stream crossings and
installation of the outfall diffuser, the requirements of the WDFW
Hydraulic Project Approval (HPA) will be implemented.
Dewatering may be required for construction of a new treatment facility
or expansion of the existing SAWTP. During construction, groundwater
that might enter excavations and trenches would be controlled to protect
the quality of foundations and fill materials. To protect water quality
in the Spokane Aquifer and any adjacent water bodies, groundwater
collected from excavations would be drained to a stormwater treatment
and collection system before discharge. A dewatering plan would be
developed to monitor groundwater withdrawal and avoid groundwater
contamination.
3.2.3.2
Operation
The intent of the Wastewater Facility Plan is to improve water quality
management in Spokane County. Increased wastewater treatment capacity
will prevent potential wastewater problems in the river and allow the
County to continue its Septic Tank Elimination Program to prevent
aquifer contamination. Effluent limitations will be set through
negotiations with Ecology for the NPDES. Operation of the treatment
plant will enhance overall water quality.
Potential impacts, if the plant were to be located in a flood-prone
area, could be mitigated by the following measures, some of which are
provided as conditions of treatment plant construction in a shoreline
area by the County Shoreline Program:
·
Locating as many of the treatment facilities as possible above
the flood level;
·
Insuring that facilities do not obstruct or impede the flow of
floodwaters; and
·
Designing facilities so that they are protected from damage and
will continue to function during flooding.
3.3
Environmental Health
This section discusses environmental health issues (e.g., noise, reuse
of reclaimed water, and biosolids utilization) associated with the
Spokane Wastewater Treatment Facility.
3.3.1.1
Noise
Noise sources in the Spokane Valley area consist of urban downtown,
urban residential, suburban residential, and industrial. The Interstate
90 (I-90) corridor is located approximately through the middle of the
City of Spokane and contributes to the ambient noise levels in the
vicinity. There are two major railroad corridors through the City and
the Mid-Valley. More than 50 trains per day use the tracks and are a
major source of noise.
Noise Overview. The human
ear responds to a wide range of sound intensities. The decibel scale
used to describe sound is a logarithmic rating system that accounts for
the large differences in audible sound intensities. This scale accounts
for the human perception of a doubling of loudness as an increase of 10
decibels (dBA). Hence, a 70 dBA sound level will sound twice as loud as
a 60 dBA sound level. People generally cannot detect differences of 1
dBA; under ideal laboratory conditions, differences of 2 or 3 dBA can be
detected. A 5 dBA change would be expected to be perceived under normal
conditions. Table 6 shows representative sounds and corresponding noise
levels produced in decibels.
When addressing the effects of noise on people, it is necessary to
consider the frequency response of the human ear. Instruments are
therefore designed to respond to or ignore certain frequencies. The
frequency-weighting most often used is A-weighting; measurements from
instruments using this system are reported in “A-weighting decibels” or
dBA. All sounds in this discussion are reported in dBA.
Factors affecting the impact that a given noise will have on a person
include frequency and duration of the noise, the absorbency of the
ground and surroundings, and the distance of the receptor from the noise
source. The receptor and the usual background noise levels also
determine the degree of impact.
Relevant Local, State, and Federal
Noise Standards and Guidelines. Spokane County has not
developed and adopted its own noise regulations. The County follows the
State of Washington noise regulations per WAC 173-60. The following
table shows the maximum permissible environmental noise levels based on
the EDNA of a particular noise source. EDNA is defined as "the
Environmental Designation for Noise Abatement, being an area or zone
(environment) within which maximum permissible noise levels are
established."
Table 6. Sound
Levels Produced by Common Noise Sources
|
Thresholds/Noise Sources |
Sound
Level (dBA) |
Subjective Evaluations |
Possible Effects on Humans |
|
Human Threshold of Pain
Carrier jet takeoff (50 ft) |
140 |
Deafening |
Continuous exposure can cause hearing damage |
|
Siren (100 ft)
Loud rock band |
130 |
|
Jet takeoff (200 ft)
Auto horn (3 ft) |
120 |
|
Chain saw
Noisy snowmobile |
110 |
|
Lawn mower (3 ft)
Noisy motorcycle (50 ft) |
100 |
Very Loud |
|
Heavy truck (50 ft) |
90 |
|
Pneumatic drill (50 ft)
Busy urban street, daytime |
80 |
Loud |
|
Normal automobile at 50 mph Vacuum
cleaner (3 ft) |
70 |
Speech Interference |
|
Large air conditioning unit (20 ft)
Conversation (3 ft) |
60 |
Moderate |
|
Quiet residential area Light auto
traffic (100 ft) |
50 |
Sleep Interference |
|
Library Quiet home |
40 |
Faint |
|
Soft whisper (15 ft) |
30 |
Minimal Effects |
|
Slight Rustling of Leaves |
20 |
Very
Faint |
|
Broadcasting Studio |
10 |
|
Threshold of Human Hearing |
0 |
Source: US Environmental Protection Agency, 1971.
Note that both the subjective evaluations and the physiological
responses are continuums without true threshold boundaries.
Consequently, there are overlaps among categories of response that
depend on the sensitivity of the noise receivers.
Spokane County has established restrictions on noise levels during
nighttime hours. Spokane County Code restricts construction activities
to the hours between 7 a.m. and 10 p.m. during which time construction
noise(s) are exempt from the provisions of Section 6.10.010 – Noise
Disturbances Prohibited. (Section 6.12.020 – Exemptions).
The City of Spokane also follows the State of Washington Maximum
Permissible Environmental Noise Levels (Table 7) and has restrictions on
noise levels during specific time periods:
"No person may make or permit any unnecessary or unusual noise between
the hours of 6 a.m. and 10 p.m. to the annoyance of others. No person
may make or permit, in the operation of a machine, in the harboring of
an animal or otherwise, any noise between the hours of 10 p.m. and 6
a.m. to the annoyance of any other person of ordinary sensibilities"
(Spokane Municipal Code, 10.08‑020 – Noise).
Table 7. Maximum
Permissible Environmental Noise Levels
|
EDNA of Noise Source |
EDNA of Receiving Property |
|
|
Class A |
Class B |
Class C |
|
Class A |
55 dBA |
57 dBA |
60 dBA |
|
Class B |
57 |
60 |
65 |
|
Class C |
60 |
65 |
70 |
Source: WAC 173-60-040
Hazardous Waste. A review
of hazardous waste site databases has revealed numerous hazardous waste
sites, including Superfund sites, within the City of Spokane and Spokane
County properties east of the city limits. The databases reviewed
include:
·
EPA's Comprehensive Environmental Response, Compensation, and
Liability Act (CERCLA) Information System CERCLIS
·
EPA's National Priorities List (NPL)
·
EPA's EnviroFacts Warehouse Web site databases
·
Ecology's Toxic Release Inventory (TRI)
·
Ecology's Resource Conservation and Recovery Information
System (RCRIS)
Site-specific database searches and site assessments would be performed
during the site selection process.
Some hazardous waste sites have leached contamin
