REZ-23-04 Correction 1 CITY OF SPOKANE VALLEY HEARING EXAMINER
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RE: Rezone from the UR-3.5 Zone to the UR-7* )
Zone; Preliminary Plat of Ponderosa Estates )
North, in the UR-7* Zone; and SEPA )
Appeal of Mitigated Determination of ) ORDER CORRECTING
Nonsignificance (MDNS); ) CLERICAL ERRORS
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Applicant: Landworks Development LLC )
IAppellant: Ponderosa Properties HOA )
File Nos. REZ-23-04/SUB-15-04/APP-03-07 )
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I. FINDINGS OF FACT
On August 30, 2007, the Hearing Examiner entered a final decision in the above matter. On
August 31, 2007, the Examiner discovered that the first two sentences of Finding of Fact#426, at
the bottom of page 58 of the decision, were inadvertently cut off when the decision was printed.
The missing three (3) lines are preserved in the electronic version of the decision, and state:
"426. Infiltration will still occur on the site;but is not being given credit for in the drainage report
in the southerly drainage channel or proposed easterly channel;a conservative assumption. The
j drainage plan will continue to allow the southerly drainage to pass through the abutting properties."
A similar printing error resulted in the last sentence of Finding of Fact#410 being repeated
at the top of page 57. A clerical error also appears in Finding of Fact#422, on page 58 of the
decision; where the words "the Guidelines," should be inserted after the word"consistent" in the
4th line.
Section 17 of the Hearing Examiner Rules of Procedure authorizes the Hearing Examiner to
reconsider or clarify a final decision to correct a clerical error.
H. ORDER
It is hereby ORDERED that the Examiner's decision in the above-referenced matter be
revised to correct the above clerical errors, and the corrected pages inserted into the decision.
This does not affect the appeal period. A copy of this Order was mailed to the applicant by
certified mail, and by regular mail to other parties of record, on August 31, 2007.
DATED this 31st day of August, 2007
SPOKANE CO 1 TY HEARING EXAMINER
41. ,
Michael C. Dempsey, WSBA#8235 l
Order Correcting Clerical Errors REZ-23-04/SUB-15-04/APP-03-07 Page 1
A detention facility must have an emergency overflow structure that is designed to accommodate
a 100-year storm event, generated under development conditions.
411. The Guidelines require that drainage infiltration systems be designed to consider the effect
that ground seepage from the facility will have on the groundwater elevations both on-site and on
nearby down-gradient properties. This includes consideration of seasonal variations, such as
frozen ground conditions and seasonal high ground water, which may affect functional use of the
drainage systems.
412. The Guidelines require the submittal of a geotechnical site characterization study when the
subsurface disposal of stormwater is proposed, to demonstrate soil infiltration suitability.
Marginal soils are typically not given "credit" for infiltration in the drainage analysis.
413. The Guidelines require that when runoff from a portion of a development site does not flow
through the detention facility, and is not retained anywhere else on site, the "bypass area" must
drain into the same channel as where the detention pond drains and cannot exceed the pre-
development level.
414. The Guidelines require that any natural draws or channels on a development site that are
used to convey stormwater to be placed in easements in the final plat. The easements must be
wide enough to contain the runoff from a 50-year storm event, plus a 30% freeboard.
415. The Guidelines require the Soil Conservation Service (SCS) Method to be used for drainage
basins greater than 10 acres, such as the current circumstances. This includes inputting the 24-
hour precipitation for the various design storms to calculate the amount of runoff from a
particular drainage basin, using the "isopluvial maps" contained in the Guidelines.
416. The Guidelines require stormwater design to be coordinated with consideration of any
wetland areas. The City Critical Areas Ordinance authorizes stormwater facilities to be located in
a wetland buffer, if sited and designed so that the buffer area as a whole preserves wetland
functions and values, taking into account the scale and intensity of the development.
417. Dick Behm contended for the SEPA appellants that the design storm precipitation levels
calculated for the Ridgeview Tributary in the 1997 Chester Creek study should be used to
calculate runoff flows for the project, instead of the precipitation levels required to be inputted
under the SCS method. This is based on the Chester Creek study showing that the Brown's
Mountain area receives 25% more precipitation in snow and rainfall than Spokane International
Airport, which rainfall levels are used to generate the precipitation levels inputted into the SCS
method.
418. Dick Behm and the SEPA appellants also contended that the three (3) 36-inch culverts
shown on the current conceptual drainage plan developed basin map were inadequate; based on
the installation of four (4) such culverts under Ponderosa Lane on the site, and under Sunderland
Road south of the site, respectively. Behm indicated that such culverts had been installed several
years ago to deal with a 10-year design storm event.
BE Findings, Conclusions and Decision REZ-23-04 SUB-15-04 APP 03-07 Page 57
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419. The original conceptual drainage report submitted for the project on January 5, 2005 used
the flows from the hydrological study contained in the Chester Creek Watershed Plan, for the
"Ridgeview Drive Tributary", to estimate drainage flows entering the site from the 2-year, 10-
year, 50-year and 100-year storm events. See letter dated 1-5-05 from Todd Whipple to City
Engineering, regarding preliminary drainage report.
420. On September 22, 2005, City Engineering advised the sponsor's engineer that it was
inappropriate to use the flows derived from the Chester Creek study. See letter dated 9-22-05
from Sandra Raskell to Craig McPhee.
I421. On December 23, 2005, Todd Whipple, the applicant's engineer, submitted a letter to City
Engineering that included a complete evaluation of the upstream off-site basins contributing
drainage to the on-site wetland, using the Soil Conservation Service (SCS) method required to be
used by the City Guidelines for Stormwater Management. Whipple noted that the flows derived
from the SCS method appeared to be considerably larger than the flows from the Chester Creek
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study; including a 100-year storm discharge of 97 cfs under the SCS analysis, and only 60 cfs
from the Chester Creek study.
422. On February 1, 2007, the applicant submitted a revised conceptual drainage plan
("conceptual drainage plan") for the project prepared by its engineering consultant, Gabe
Gallinger of Landworks Engineering, Inc. The conceptual drainage plan was accepted by City
Engineering, as being consistent with the Guidelines, subject to the submittal of a final drainage
report and plans that conform to such regulations, prior to final plat approval.
423. Dick Behm indicated that the a new floodplain maps for the Chester Creek area were close
to being issued, which maps would significantly reduce the area of the floodplain. This suggests
that revisions have been made to the 1997 Chester Creek hydrological study, including the
calculation of reduced flows reaching the floodplain.
424. The revised conceptual drainage plan also calculated the basin flows for the project based on
the SCS method required by the Guidelines for Stormwater Management. There is not a
sufficient basis in the record to require use of the precipitation levels contained in the 1997
Chester Creek study, or to find that the proposed culverts leading out of the wetlands are
insufficient to convey the required design storm flows.
425. The SEPA appellants and other residents contended that the proposed narrowing,
redirecting, berming and reducing the level of infiltration and storage capacity of the natural
drainage channel located in the south end of the site, for the conceptual drainage plan, in
conjunction with the inadequate culvert sizing, would cause flooding during large storm events to
properties abutting the south end of the site.
426. Infiltration will still occur on the site; but is not being given credit in the drainage report for
in the southerly drainage channel or proposed easterly channel; a conservative assumption. The
drainage plan will continue to allow the southerly drainage to pass through the abutting properties
HE Findings, Conclusions and Decision REZ-23-04 SUB-15-04 APP 03-07 Page 58