HomeMy WebLinkAboutStudies APPLICANT 9/28/2022September 28, 2022 Branch
ENGINEERING-
GRADING PIAN REPORT
636 S 70TH, LLC
TENTATIVE SUBDIVISION
Branch Engineering Inc. Project No. 21-287
The following narrative (along with the noted plan sheets and referenced reports) are intended
to follow the format provided per City of Springfield city code section 3.3-530.B items 1-8.
Attached to this document are the Tentative Subdivision Existing Conditions and Site Plan.
1. Ekdsting and proposed details and contours (S-foot intervals) of property;
Response:
Existing Site Conditions:
The site of the project addressed in this report is located at Tax Map: 18-02-02-23, Tax Lot
4300, totaling 1.76 -acres in Springfield, Oregon The site is currently undeveloped and
located on the west side of S 70- Street between Glacier Drive and Ivy Street and extends
westward to the current terminus of S 69- Place. S 70m Street is not developed up to current
city standards with a ditch along its west side for stormwater drainage.
The site has a fairly consistent slope from its southwesterly corner to its northeasterly
corner of approximately 896 All of the existing runoff from the site flows via overland
sheet flow to the backyards of the adjacent properties to the north of the site.
The existing site consists of several trees, S of which are directly impacted by the Public
Improvements. The remaining trees slated for removal conflict with building envelopes
shown on the tentative subdivision plan
See Sheet 1 Tentative Subdivision Existing Conditions for additional information on
existing contours and conditions.
Proposed Grading Plan:
Please see Sheet 2 Tentative Subdivision Site Plan for reference. Proposed grading primarily
consists of a 41 -foot roadway dedication to extend S 69- Place to S 70m Street which will
include a 20 -foot -wide paving width with setback sidewalks, and the reconstruction and
improvement of the west half of S 70- Street right-of-way along the frontage of the site.
The entirety of the public improvements will consist of approximately 0.55 acres.
Due to the nature of the slopes on site, the pavement will have a shed cross section to
match the natural slope of the site.
All fill material will be placed in lifts and compacted per geotechnical recommendations.
Site strippings are expected to be removed from the site, though some could be stockpiled
and then redistributed on non-paved(non-gravel)/disturbed soil areas and areas to be re-
seeded as post -construction conditions and geotechnical recommendations allow.
EUGENE -SPRINGFIELD ALBANY
310 Sth Street, Springfield, OR 97477 1 p- 541.746.0637 1 w .brancheng ineering.com
Grading Plan Report (21-287)
September 28, 2022
2. Details of terrain and area drainage;
Response:
The following is taken from the Proposed Development Stormwater Description section in
the Stormwater Report that is included within the Tentative Subdivision Plan submitted
prior to this application
"The proposed stormwater development for the subject property will consist of four curb inlets along
the northerly portion of S 60" Place and one along S 70" Street. The road will shed water to the
north to match the existing direction of the slope on-site."
It should be noted that the Stormwater Report also details that a portion of existing
improvements to the south along S 69- Place will also be draining through the site. The
Stormwater Report also details the appropriate pipe diameter to convey the stormwater
offsite and downstream to the existing public stormwater capture system in S 70- Street.
3. Location of any existing buildings or structures on the property where the work is to
be performed the location of any existing buildings or structlues on land of adjacent
owners which are within 100 feet of the property or which may be affected by the
proposed grading operations, and proposed or approximate locations of structures
relative to adjacent topography;
Response:
There are various single-family residences that surround the site. To the north are four
properties that are directly affected by the proposed grading of the site. These homes are
currently in the path of all the drainage that comes off the existing slope. According to
one of the neighbors, water runoff from this site has been a major issue for his foundation.
Fortunately, the grading and the conveyance of stormwater from the improvements will
remove anywhere between 70-7596 of the current area draining to the north, and instead
direct it through the piped system to the public stormwater system on S 70- Street.
The property located directly southeast of the property has agreed to a permanent slope
easement on its north side to accommodate the public improvements running through the
site.
The remaining properties to the south and the west are all uphill of the site, and will remain
unaffected by any improvements.
4. The direction of drainage flow and the approximate grade of all streets with the final
determination to be made as specified in Subsection D., below;
Response:
All of the drainage will be directed from the southwest of the property to the east as
described in the Stormwater Report referenced above. The grade of the street will range
between 0.5%- 8.696 Building envelopes are also depicted on the site plan along with their
proposed driveway approaches.
Branch Engineering, Inc.
Grading Plan Report (21-287)
September 28, 2022
S. Uniting dimensions, elevations, or finished contours to be achieved by the grading,
including all cut and fill slopes, proposed drainage channels, and related construction;
Response:
All dimensions, elevations, and finished contours to be achieved by the grading, including
all cut and fill slopes, proposed drainage channels, and related construction can be seen
on Sheet 2 Tentative Subdivision Site Plan.
6. Detailed plans and locations of all surface and subsurface drainage devices, walls,
dams, sediment basins, storage reservoirs, and other protective devices to be
constructed with, or as a part of, the proposed work, together with a map showing
drainage areas, the complete drainage network, including outfall lines and natural
drainageways which may be affected by the proposed development, and the estimated
run-off of the area served by the drains;
Response:
Pont curb inlets will be located on the northerly side of the extended S 69' Place which
will capture the runoff from the street as well as the lots to the south which will weephole
to the street. The roofs from the northerly lots will be directed straight to the stormwater
main located within the extended street The landscaping on the northerly lots will likely
be similar to existing draining conditions. All grading for individual lot development will
be addressed during home construction, as necessary.
Originally, the plan was to have the proposed system connect into the piped system on S
70m Street. However, after extensive discussion with SUB Water, it was concluded that any
pipe crossings along S 70m Street shouldbe avoided, as SUB Water has a water transmission
line along the west side of S 70m Street. Any damage done to this line would remove water
service to most of the easterly Springfield area until a repair is made. To avoid that, the
following changes to the plan are described below.
A manmade ditch is currently located along the westerly edge of S 70m Street. The proposed
improvements will include a setback sidewalk and curb and gutter along the frontage of
the property along S 70m Street The existing ditch will continue to function as normal to
the north and south of the subdivision A ditch inlet will capture water in the upstream
ditch and will join the proposed stormwater drainage system to outfall into the
downstream ditch. This ditch is connected to the piped system on S 70- Street at the
southwest corner of the Glacier Drive and S 70- Street intersection.
7. A schedule showing when each phase of the project will be completed, including the
total area of soil surface which is to be disturbed during each stage, and estimated
starting and completion dates; the schedule shall be drawn up to limit to the shortest
possible period the time that soli is exposed and unprotected In no event shall the
existing "natural" vegetative ground cover be destroyed removed or disturbed more
than 15 days prior to grading or construction of required improvements. Within 15
days of grading or other pre -development activity that removes or significantly
disturbs ground cover vegetation, exposed soil shall either be built upon (i.e., covered
with gravel, a slab foundation or other construction), landscaped (i.e., seeded or planted
with ground cover) or otherwise protected;
Response:
As per most Public Improvements, all the subsurface structures and pipes will be
constructed first and backfilled with crushed rock as the work progresses. The same will
be true for the grading of the road. Any additional grading that removes ground cover will
Branch Engineering, Inc. 3
Grading Plan Report (21-287)
September 28, 2022
follow the erosion control permit that is made part of the Public Improvement plan, which
might include items like mulch matting, bamboo lattice matting or other erosion
prevention measures.
As the timing of the start of construction is unknown at this time, a schedule will be
generated as part of the Public Improvement Project submittals that will meet the
standards detailed in this item
8. The Grading Plan shall be prepared by a C ivi1 Engineer.
Response:
All grading plans were prepared under the responsible charge of a licensed professional
Civil Engineer practicing under a valid registration in the State of Oregon.
nWnenPeee�n UTALLYSIGNED
OREGON
29� °Fc. 21, t/
EXPIRES: 12/31/22
Branch Engineering, Inc.
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