HomeMy WebLinkAboutEx06_SEPA_Response_Comments
Department of Natural Resources and Parks
Wastewater Treatment Division
King Street Center, KSC-NR-5500
201 South Jackson Street
Seattle, WA 98104-3855
February 19, 2021
[via e-mail: vdolbee@rentonwa.gov]
City of Renton
Department of Community & Economic Development – Planning Division
1055 S Grady Way
Renton, WA 98057
Dear Ms. Dolbee,
Thank you for your comments on King County’s proposed Loop® Compost Pilot Project at
South Treatment Plant. See below for responses to each of your comments and questions.
Comment 1: We request the following mitigation measure be added to the project: King
County should establish a complaint hotline, where odor complaints can be directed. If
complaints are received King County should immediately address the odor causing
concerns and deploy additional odor reduction measures to reduce these off-site impacts.
King County should notify the City of any complaint received and how they are
addressing the complaint.
King County response: The project is located within the property boundary of King County’s
South Treatment Plant (STP). The plant has a 24-hour odor control hotline which is (206) 263-
1760. Details of STP’s odor complaint process can be found here:
https://www.kingcounty.gov/depts/dnrp/wtd/response/odor-control.aspx. Before compost
operations commence, the Department of Ecology must approve the compost project’s
operations plan, according to state biosolids regulations under WAC 173-308. The approved
operations plan will address in detail how odor is controlled to mitigate off-site impacts,
especially in the event of a complaint where the compost facility is determined to be the source
of the odor.
The County requests that upon submittal, the City of Renton review the temporary use permit
application for this facility and evaluate if further discussion of mitigation is warranted at that
time.
EXHIBIT 6
RECEIVED
Clark Close 04/19/2021
PLANNING DIVISION
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Comment 2: Please clarify where compost will be disposed while seeking Class A status.
King County response: Aerated static pile composting, the technology used in this pilot project,
is an approved Class A “process to further reduce pathogens” under WAC 173-308-170(3). The
WAC includes requirements for minimum temperature of piles and the minimum duration the
temperature must be maintained, as well as a maximum density of Salmonella sp. bacteria.
Ecology must issue a Final Approval of the County’s operations plan, which would confirm the
County’s proposed Class A classification, before the facility begins operating.
During operations, the County will monitor temperature and pathogen density on an ongoing
basis. If Class A requirements are not met, the County would follow the product quality
contingency plan outlined in the project’s approved operations plan. While exact details are still
in development, the contingency plan will include at least two options: 1) re-mix and re-compost
the batch to meet process requirements, or 2) land-apply the compost as Class B biosolids,
according to the County’s existing Ecology-approved Class B procedures. Similar to existing
biosolids management practices, if a compost batch were to fail to meet Class B biosolids
requirements, it would be landfilled.
Comment 3: The SEPA Checklist indicates that each batch can produce 400 cubic yards
or more of compost. Truck trips associated with removal of the compost should be
disclosed and mitigated.
King County response: The compost facility will produce approximately 2,500-3,500 cubic yards
of compost per year. The additional truck trips for the compost facility represent substantially
less than 1% of STP’s total annual truck traffic and will not be discernably different from the
existing industrial activities and existing truck trips in the area. Biosolids make up only a portion
of the activities and truck trips associated with STP, but for comparison, approximately 10 trucks
leave STP per day to deliver Class B Loop biosolids to King County’s customers, for a total of
3,650 annual truck trips from STP’s distribution of Loop.
The proposed project will result in a decrease of approximately 26 truck trips per year of Loop
biosolids that would otherwise be transported off-site, and an increase of approximately 150
truck trips per year for delivery of compost bulking agents, for a net increase of approximately
124 trips per year. Bulking agents will be delivered on average once per week, and trips for
removal of finished compost will occur on average twice per week.
Comment 4: Clarification is needed as to what the health impacts will be to the
environment and surrounding area for the 11 toxic air pollutants (TAPs) that exceed the
de minimis thresholds and Renton’s air quality.
King County response: The Puget Sound Clean Air Agency (PSCAA) is currently reviewing the
proposed facility’s Notice of Construction application under the New Source Review process.
One element of this process is a review of the air quality impacts of Toxic Air pollutants (TAPs)
to demonstrate that the proposed project does not have the potential to adversely affect the health
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of people in the surrounding community. All of the 11 TAPs that exceed the de minimis
thresholds had emission rates below their Small Quantity Emission Rates (SQERs). Therefore,
according to PSCAA Regulation III Section 2.07 (c) (1) (A), the facility has demonstrated
compliance with the Acceptable Source Impact Levels (ASILs) for the TAPs. Ambient impacts
below ASILs do not have the potential to adversely affect the health of people in the surrounding
community.
Under WAC 173-460 (as in PSCAA Regulation I, Section 6.01), facilities submitting a NOC
application are required to complete a first-, second-, or third-tier review of the air quality
impacts of TAPs to demonstrate that the proposed project does not have the potential to
adversely affect the health of people in the surrounding community. TAPs include both
carcinogens and non-carcinogens. WAC 173-460-150 lists the regulated TAPs along with their
respective averaging period, Acceptable Source Impact Levels, Small Quantity Emission Rates,
and de minimis emission values. Demonstrating compliance with the relevant standards by
comparing project emissions to the TAP values listed in WAC 173-460-150 is considered to be a
first-tier review.
The de minimis values are defined as the maximum level of emissions that do not pose a threat to
human health or the environment. If emissions of a given TAP from a source do not exceed the
associated de minimis emission values, then that TAP is exempt from further New Source
Review evaluation. However, if emissions of a given TAP do exceed the associated de minimis
emission values, then further NSR evaluation is required and Best Available Control Technology
for Toxics (tBACT) must be demonstrated.
In addition to tBACT, each TAP must demonstrate compliance with its respective Acceptable
Source Impact Levels by either having an emission rate below the Small Quantity Emission
Rates or conducting air dispersion modeling. The Small Quantity Emission Rate is defined as a
level of emissions below which dispersion modeling is not required to demonstrate compliance
with Acceptable Source Impact Levels values. The Small Quantity Emission Rates value for
each TAP uses a very conservative, assumed dispersion rate to predict whether the emissions
will have an ambient impact below the Acceptable Source Impact Levels. Ambient impacts
below the Acceptable Source Impact Levels do not have the potential to adversely affect the
health of people in the surrounding community.
Of the 33 TAPs identified as having potential emissions from the Facility, 11 exceeded their de
minimis thresholds. These 11 TAPs, their estimated potential to emit, and their Small Quantity
Emission Rates are listed in Table 1. None of the 11 TAPs exceed the Small Quantity Emission
Rates; therefore, according to PSCAA Regulation III Section 2.07 (c) (1) (A), the Facility has
demonstrated compliance with Acceptable Source Impact Levels for TAPs. The first-tier analysis
may be considered complete without requiring dispersion modeling.
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Table 1. TAPs with emission rates exceeding de minimis levels, compared to SQER
TAP CAS Number Emission Rate
(lb/averaging
period)
Averaging
Period
SQER
(lb/averaging
period)
Exceeds
SQER?
1,1,2-
Trichloroethane
79-00-5 0.85 lb/year 10 No
Allyl chloride 107-05-1 2.1 lb/year 27 No
Ammonia 7664-41-7 2.9 lb/24-hr 37 No
Benzene 71-43-2 3.4 lb/year 21 No
Carbon
tetrachloride
56-23-5 9.2 lb/year 27 No
Chloroform 67-66-3 1.7 lb/year 7.1 No
Ethylbenzene 100-41-4 5.4 lb/year 65 No
Hydrogen
sulfide
7783-06-4 0.10 lb/24-hr 0.15 No
Napthalene 91-20-3 1.4 lb/year 4.8 No
Triethylamine 121-44-8 0.78 lb/24-hr 15 No
Diesel PM — 0.51 lb/year 0.54 No
CAS = Chemical Abstracts System
Comment 5: Clarification is also needed as to whether the 11 TAPs that exceed de
minimis thresholds are not required to demonstrate compliance because they do not
exceed their Small Quantity Emission Rate (SQER) – even though they exceed the de
minimis threshold for health impacts.
King County response: Please see the response to Comment 4 above.
Comment 6: Table 1, Page 9 of the SEPA Checklist, identifies odor units per minute
(OU/min). Can King County please compare the OU/min expected to be produced from
this site to the Cedar Grove Composting site in King County?
King County response: In 2019, Cedar Grove’s facility in Maple Valley processed 239,523 tons
of green waste and food waste. The County’s Loop compost pilot facility will process
approximately 2,000 tons of material (780 wet tons of biosolids and 600-1300 tons of bulking
material/woody material). Therefore, the Loop compost pilot facility will process less than 1
percent of the material processed by the Cedar Grove’s Maple Valley facility. King County’s
compost pilot facility will be more similar in size and technology to the Woodland Park Zoo’s
compost facility, which processes about 500 tons per year on 0.23 acres and produces the
popular ZooDoo compost product. The Woodland Park Zoo’s compost facility is located near
publicly accessible areas of the zoo, yet receives no odor complaints due to its well-managed
operations.
It is generally believed that the aerobic composting of biosolids produces less odor than aerobic
composting of green waste and food waste. However, odor emissions from the Cedar Grove
Facility are not available for comparison. Common odorous compounds include VOCs,
ammonia, and reduced sulfur compounds. Emissions of reduced sulfur compounds are typically
low for properly managed composting processes and a minor contributor to odors. Composting
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using aeration like the County proposes for this facility has a control efficiency of 75 percent or
greater.
Odor emissions are regulated through PSCAA Regulation I, Section 9.11, which states: “It shall
be unlawful to cause or permit the emission of an air contaminant in sufficient quantities and of
such characteristics and duration as is, or is likely to be, injurious to human health, plant or
animal life, or property, or which unreasonably interferes with enjoyment of life and property.”
In the PSCAA NOC permit application, the County demonstrates that odor emissions from the
facility are unlikely to contribute significantly to ambient odors or to cause a violation of
PSCAA Regulation I, Section 9.11 through dispersion modeling of worst-case odor emissions.
Comment 7: Please confirm that you evaluated impacts on the great blue heron which
are known to nest at the Black River Riparian Forest, just north of the project site.
King County response: The SEPA checklist identifies the presence of the great blue heron
rookery in the Black River Riparian Forest in Section B.5.a. Chronic human disturbances in the
vicinity of a heron rookery can cause nesting failure. The proposed project is unlikely to generate
noises or other disturbances that would be discernably different from the existing industrial
activities in the area.
Comment 8: Please confirm that that proposed project is not exacerbating the five (5)
existing leaking underground tanks (LUSTs) located within the vicinity of the project site,
as identified in Section B-7, Environmental Health.
King County response: The project will not affect any known LUSTs. Of the five LUSTs cited in
the SEPA checklist, only one was located on the STP campus, but not in the immediate vicinity
of the proposed project site. This LUST was reported to Ecology in the 1990s and voluntarily
cleaned up.
Comment 9: In Background Section A-11, you’ve indicated that three (3) blowers would
be in nearly constant operation to active composting and curing areas. Please clarify the
direction of the blowers and if these are the same system described in the aeration
process.
King County response: The three blowers are the primary components of the forced aeration
system described in Section A.11 of the SEPA checklist, the blowers provide reversing aeration
(positive and negative). The aeration system will run according to a system of temperature
sensors and programmable controls for optimal process conditions and odor control, according to
desired testing parameters, industry standards and best management practices. The aeration
system is automatically reversing, drawing cool air into the compost piles either from the top or
bottom. The negative aeration process will draw air from beneath the pile, into air ducts placed
on-grade beneath the pile, and out to a manifold directing the collected air to an odor-scrubbing
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biofilter. The positive aeration process will draw cool air into the fan and push it into the plenum
on the floor and up through the pile, which is covered by a biolayer of finished compost or wood
chips for odor and temperature control.
Thank you again for your comments. If you have additional questions or concerns, you may
contact me at (206) 477-5395 or jacob.sheppard@kingcounty.gov.
Respectfully,
Jacob Sheppard, Environmental Planner
King County Department of Natural Resources and Parks – Wastewater Treatment Division
cc (via email): Katherine Fischer, Environmental Programs Managing Supervisor
Ashley Mihle, Project Manager
Clark Close, Senior Planner, City of Renton
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