23-105388-UP-Stream Buffer Intrusion Justification Narrative-12-05-23STREAM BUFFER INTRUSION JUSTIFICATION NARRATIVE
for
PRELIMINARY PLAT of CREEKWOOD
Prepared by:
Barghausen Consulting Engineers, Inc.
December 1, 2023
PROJECT OVERVIEW
The site abuts the road stub of 22nd Avenue SW and the angle transition of 21st Avenue SW to 21st Way
SW. Currently 22nd Avenue SW is a long dead-end street that terminates at the site's northern boundary.
The Creekwood Plan proposes to construct a new connection (Road A) between 22nd Avenue SW and
21st Avenue SW.
Construction of the new road will have the benefit of (1) eliminating the long dead-end in the plat to the
north and (2) providing a second access for the neighborhood of close to 100 homes to the north which
currently has only a single access to 21st Avenue SW at 307th Street SW. The new road connection will
enable emergency vehicles to access the site and adjacent neighborhood to the north from two separate
locations. Both of these represent substantial public benefits that cannot be achieved without making this
connection via Road A.
Due to physical constraints of the site and the extensive critical areas and their associated buffers, Road A
must cross a ravine discussed below in the section on Critical Areas. The ravine crossing is designed to
be as close to the north property line as possible to minimize the amount of stream buffer intrusion required,
and to avoid directly impacting the emergent point for “Drainage Y.”
The physical characteristics of the ravine and surrounding area in conjunction with the city public works
standards limit the available options for constructing the crossing. The depth of the ravine at the crossing
point and the configuration of the existing road stub precludes the use of retaining walls or bridge structure.
The most feasible option is to use a reinforced structural fill, but a traditional 2H:1V fill will modestly
encroach onto the “Drainage Y” emergent point. Therefore, the applicant is proposing to construct the
crossing with a geogrid-reinforced structural fill slope for Road A where it crosses the existing ravine just
east of the intersection with 22nd Avenue SW. Please see the enclosed Geogrid-Reinforced Slope
Assessment & Global Stability Analysis letter prepared by Earth Solutions NW LLC dated October 30, 2023.
Due to the proximity of the emergent point of Drainage “Y” and the depth of[ the ravine, the proposed
geogrid-reinforced fill will encroach into the 50’ stream buffer that extends in a half-circle around the
emergent point. This encroachment will be temporary as it will be revegetated upon completion, but such
temporary encroachments still require approval under FWRC 19.145.330.
JUSTIFICATION FOR 19.145.330 INTRUSION INTO STREAM BUFFERS
(1) A request for an intrusion into a stream buffer will be reviewed and decided upon using process III
in Chapter 19.65 FWRC. Responses to decisional criteria and design requirements in this section
shall be included in the critical areas report.
Response: The responses to all review criteria are provided in Chapter 6 of the Wetland & Fish &
Wildlife Habitat Assessment and Buffer Enhancement Plan prepared by Soundview Consultants
LLC (SVC) and copied to this narrative as “SVC Response”.
Additional responses by Barghausen and the applicant’s attorney are also provided in the following
narrative.
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(2) Stream buffer intrusions may be permitted with a buffer enhancement plan. The applicant shall
demonstrate that the remaining and enhanced reduced buffer will function at an equivalent or
higher level than the standard buffer. The plan shall provide an assessment of the following existing
functions and conditions of the buffer and the effects of the proposed modification on those
functions:
(a) Habitat;
(b) Water quality;
(c) Stormwater retention capabilities;
(d) Groundwater recharge; and
(e) Erosion protection.
Response: Please see Chapter 7 of the Wetland & Fish & Wildlife Habitat Assessment and
Buffer Enhancement Plan prepared by SVC.
(3) The city may approve a stream buffer intrusion based on the following criteria:
(a) It will not adversely affect water quality;
SVC Biologist Response1: The proposed access road and stormwater connection are not
anticipated to adversely affect water quality. Construction of the proposed access road and
stormwater connection will require 2,280 square feet of intrusion to the buffer of Drainage Y.
The existing buffer is degraded due to ongoing erosion issues associated with the ravine
where Drainage Y is located, and the presence of trash, debris, and non-native invasive
species and a sparse understory. In order to offset impacts to the drainage, the northern end
of the ravine will be filled and graded to replicate site conditions prior to erosion of the ravine
as recommended by ESNW. The impacts to the buffer of Drainage Y will be restored by
seeding the fill slope with an erosion control mix. The remaining buffer will be enhanced by
removing degradations (trash, debris, and non-native invasive species) and planting native
shrubs and groundcover. Overall, these actions will prevent excess sediment loads from
entering Drainage Y, reduce turbidity associated with excess sediment, remove sources of
pollutants from the buffer, and provide a dense suite of native shrubs and groundcover in the
understory which will improve filtration for surface runoff entering Drainage Y, resulting in a
net lift in water quality for surface runoff entering Drainage Y.
Barghausen Response: Construction of the new road will permanently cut off upstream
stormwater surface flow to the top of the ravine which has been a factor contributing to the
degradation of the downstream portion of Drainage Y. Significant erosion control measures
will be designed and implemented by the contractor during road and site construction to
ensure protection of down-slope wetland, streams, and slope vegetation. The reinforced
slope is not a pollution-generating surface, so once it is constructed and stabilized, it will
function the same as the natural environment. All project-generated stormwater will be
treated and released to the existing tightline pipe system that bypasses the ravine area.
(b) It will not adversely affect the existing quality of wildlife habitat within the stream or buffer
area;
SVC Biologist Response1: The proposed access road and stormwater connection will not
adversely affect the existing quality of wildlife habitat within Drainage Y or the associated
buffer. Buffer enhancement actions will remove degradations (non-native invasive species,
trash, and debris) and improve habitat within the buffer by planting a suite of native
1 Wetland & Fish & Wildlife Habitat Assessment and Buffer Enhancement Plan by SVC dated November 14, 2023
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understory plantings. The establishment of a native plant community in the understory will
improve habitat by providing increased cover and shading along the banks of the drainage
and providing potential food sources and cover for native wildlife. As such, the stormwater
connection will not adversely affect existing wildlife habitat within Drainage Y or the
associated buffer.
(c) It will not adversely affect drainage or stormwater retention capabilities;
SVC Biologist Response1: The proposed access road and stormwater connection will not
adversely affect the existing drainage or stormwater retention capabilities associated with
the buffer of Drainage Y. The existing buffer has little potential to retain stormwater due to
the steep slope. As part of the construction of the proposed access road, the buffer will be
filled and graded to stabilize the slope, as recommended by ESNW. These actions, combined
with the addition of native plantings within the buffer, will improve drainage and stormwater
retention capabilities by slowing surface runoff entering Drainage Y and preventing further
erosion, and therefore sedimentation of Drainage Y and downgradient waters.
Barghausen Response: There are no drainage or stormwater elements to the reinforced
slope. The existing piped storm drainage system will be undisturbed by the reinforced slope.
The permanent stabilization of the ravine as proposed at the road crossing will provide
additional protection to the existing pipe network, ravine, as well as the remaining hillside by
ensuring that future erosion and degradation cannot occur from precipitation events at the
top of the ravine.
(d) It will not lead to unstable earth conditions nor create erosion hazards;
SVC Biologist Response1: The proposed access road and stormwater connection will not
lead to unstable earth conditions or create erosion hazards. As mentioned above, as part of
the access road construction, 2,280 square feet of the ravine north of where Drainage Y is
situated will be graded, filled, and seeded with an erosion control mix to improve slope
stability and prevent future erosion hazards. In addition, the remaining buffer areas will be
planted with a suite of native shrubs and groundcover, which will provide increased root
structure to improve slope stability. Overall, the proposed project is anticipated to improve
earth conditions and alleviate existing erosion hazards.
Barghausen Response: See response to Section 3(a) above. In addition to mitigating
upstream surface flow impacts, the proposed fill will incorporate remediation of exposed
portions of the ravine side slopes in the vicinity of the crossing that are contributing to local
instability and surface sloughing during periods of heavy rainfall, resulting in further
degradation of Drainage Y. If left unchecked, these areas are likely to continue to slough as
the intensity of rainfall events increases in years to come, potentially leading to a complete
blockage of Drainage Y further downstream. The construction of the proposed crossing of
Road A will permanently mitigate this concern.
(e) It will not be materially detrimental to any other property in the area of the subject property
nor to the city as a whole; and
SVC Biologist Response1: The proposed project will not be materially detrimental to other
properties in the vicinity of the subject property or the City. As mentioned above, the
proposed project will improve stability of the ravine where Drainage Y is located. The stability
of the ravine has been an ongoing issue of concern for adjacent property owners and the
City (Associated Earth Sciences, 2017; GeoResources 2019, and 2020).
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Barghausen Response: The existing piped storm drainage system, which handles offsite
upstream drainage, will be undisturbed by the reinforced slope. The permanent stabilization
of the ravine as proposed at the road crossing will provide additional protection to the existing
pipe network, ravine, as well as the remaining hillside by ensuring that future erosion and
degradation cannot occur from precipitation events at the top of the ravine. All project-
generated stormwater will be treated and released to the existing tightline pipe system that
bypasses the ravine area. There will be no impact to other properties or the city as a whole
from the proposed reinforced slope. The applicant proposes to dedicate the critical areas
tract (Tract C) to the city of Federal Way at the time of plat recording.
(f) It is necessary for reasonable development of the subject property.
Barghausen Response: The applicant for this project has filed multiple applications for
preliminary plat over a number of years. All prior applications have offered solutions to
construct a road to cross the ravine, because crossing the ravine is the only way to achieve
a reasonable development outcome for the property. Prior solutions included retaining walls
of varying design, and a non-reinforced slope with fill combined with piping Stream/Drainage
Y to the bottom of the ravine.
In 2023, the city approved the concept of using a reinforced cast in place retaining wall;
however, the approval was issued with conditions that are physically impossible to meet. The
current proposal/solution is a reinforced vegetated slope, which alleviates the need for
vehicular access to maintain the ravine crossing (as required for a tall retaining wall) and
effectively has minimal impact to the surrounding forested slope (as noted in SVC report with
buffer enhancement).
Legal Response2: In interpreting municipal ordinances, the Washington State Supreme
Court has established that the same rules of interpretation for state statutes apply. Sleasman
v. City of Lacey, 159 Wn.2d 639, 151 P.3d 990 (2007). According to Sleasman, an
unambiguous ordinance should be interpreted according to its plain meaning, and only
ambiguous ordinances require analysis of statutory construction. Sleasman at 643. When
statutory construction is required, the goal in construing zoning ordinances is to determine
legislative purpose and intent. HJS Dev., Inc. v. Pierce County, 148 Wash.2d 451, 472, 61
P.3d 1141 (2003). Sleasman also notes that if a zoning ordinance is ambiguous, it must be
interpreted in favor of the property owner. Id.
According to the Federal Way Code, the City may approve a stream buffer intrusion based
on certain criteria outlined in FWRC 19.145.330(3). Specifically, FWRC 19.145.330(3)(f) sets
forth six separate criteria all of which must be met before the city may ap prove a stream
buffer intrusion. These criteria include whether the buffer intrusion “is necessary for
reasonable development of the subject property.” In contrast, reasonable use exceptions are
a mechanism by which a local jurisdiction may grant relief from code requirements when
compliance leaves no reasonable use of the property. Reasonable use exceptions are
included in zoning codes to avoid regulatory takings. The City of Federal Way has codified
its reasonable use exception process in FWRC 19.145.090.
Both the terms “reasonable development” and “reasonable use” are undefined in Title 19 or
anywhere else in the code. We view FWRC 19.145.330 and FWRC 19.145.090 as
unambiguous. It is self-evident that “reasonable development” and “reasonable use” are two
separate terms with distinct meanings. The use of two separate terms suggests that they
hold different definitions and purposes within the context of the code. Indeed, if these two
terms were intended to convey the same meaning, then there would be no need to use
separate terms. For example, the criteria for approval of a buffer intrusion could have
2 Applicant’s attorney Nancy Bainbridge Rogers, Cairncross & Hempelmann
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included a requirement to obtain a reasonable use exception under FWRC 19.145.090. The
City's decision to include both "reasonable development" and "reasonable use" in the code
demonstrates an intention to distinguish between the two concepts. Furthermore, since both
terms lack definitions, it is appropriate to interpret them according to their plain meaning to
avoid ambiguity. (Also, if any ambiguity is found, then that will require the terms to be
interpreted in favor of the property owner, which will also lead to a conclusion that the criterion
“necessary for reasonable development” found in the buffer intrusion code means something
different from the City’s code governing the much more limited “reasonable use exceptions.”)
Ultimately, the criteria outlined in the code for approving a stream buffer intrusion focus on
various factors such as water quality, wildlife habitat, drainage, erosion hazards, and the
overall impact on neighboring properties and the city as a whole, as well as a showing of
necessity to achieve a “reasonable development.” These criteria go beyond the scope of
reasonable use and provide an avenue for approving developments that meet the specified
standards. The term "reasonable development" cannot be equated with "reasonable use" in
this context. The City's intent, as reflected in the code, is to evaluate and consider the impacts
to a stream buffer and benefits of a proposed development based on the outlined criteria for
a buffer intrusion, rather than simply restricting development to the bare reasonable use
allowed under the Constitution. The City has the authority to approve a stream buffer intrusion
if the proposed development meets the specified criteria in FWRC 19.145.330, including that
the approval is necessary for reasonable development of the subject property.