HomeMy WebLinkAbout11-07-2013 Planning and Zoning CommissionPLANNING AND ZONING COMMISSION
Thursday, November 7, 2013 - 7:00 PM
Formal Meeting
Iowa City City Hall
Emma J. Harvat Hall
410 E. Washington Street
AGENDA:
A. Call to Order
B. Roll Call
C. Public Discussion of Any Item Not on the Agenda
D. Rezoning Item
Discussion of an application submitted by Iowa River Redevelopment, LLC for a rezoning of
approximately 2.5-acres of property from Community Commercial (CC-2) zone to Planned Development
Overlay/Comm unity Commercial (OPD/CC-2) zone located at 21 W. Benton Street and 820 S. Riverside
Drive. (REZ13-00022)
E. Consideration of Meeting Minutes: October 17, 2013
F. Other
G. Adjournment
Upcoming Planning & Zoning Commission Meetings
Formal: November 21 1 December 5 / December 19
Informal: Scheduled as needed,
STAFF REPORT
To: Planning & Zoning Commission
ltem:,REZ013-00022
21 W. Benton Street & 820 Riverside Drive
GENERAL INFORMATION:
Applicant:
Contact:
Property Owner:
Requested Action:
Purpose:
Location:
Size:
Existing Land Use and Zoning:
Surrounding Land Use and Zoning:
Comprehensive Plan:
Prepared by: Karen Howard
Date: November 7, 2013
Iowa River Redevelopment, LLC
105 511, St.
Coralville, A 52241
Mark Seabold
2834 Northgate Drive
Iowa City, A 52245
Kevin O'Brien
105 5th St.
Coralville, IA 52241
Rezoning from CC-2 to OPD-CC-2;
Planned Development Rezoning to allow a
mixed -use development with certain
modifications to the underlying zoning and
a reduction in the 50-foot buffer along the
Iowa River through the Sensitive Areas
ordinance
Development of a 5-story mixed -use
building with retail, office, and residential
with frontage along Benton Street and the
Iowa River and a second 5,000 square foot
retail building
21 W. Benton Street & 820 W. Riverside Dr.
Approximately 2.5 acres
Vacant commercial building; CC-2
North:
Commercial; CC-2
South:
Commercial; CC-2
East:
Iowa River
West:
Commercial; CC-2
The Riverfront Crossings Master Plan, an
adopted element of the Comprehensive
Plan identifies this area as appropriate for
mixed -use development.
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File Date:
8/29/13
Revised plan submitted 10121/13
45 Day Limitation Period: December 4, 2013
BACKGROUND INFORMATION:
Iowa River Development, LLC, has submitted an application for a planned development
rezoning for property at 21 W. Benton Street, site of the old Mumm's Saloon, which directly
abuts the Iowa River. The application also includes the adjoining property at 820 Riverside
Drive, which is adjacent to and shares a parking lot with Staples. The planned development
process will allow the applicant to develop the site in a manner that is oriented toward the Iowa
River and the planned west bank section of the Iowa River Corridor Trail (IRC). Because the
site is constrained by the McDonald's restaurant property and the Staples property, the
applicant is requesting a reduction in the 50-foot stream corridor buffer along the Iowa River.
The applicant is proposing to use the slope along the riverbank to construct a level of
underground parking that will be floodable in the event of significant flooding along the river.
The submitted site plan and drawings indicate that the alignment of the Iowa River Corridor
Trail would be shifted down the slope from where it was modeled a few years ago and
developed with public riverfront amenities, including a plaza and potential river access for
fishing and boating.
In addition to tearing down the now vacant Mumm's building and developing a new mixed -use
building on that site, they are also proposing to construct a smaller retail building adjacent to
the Staples building. The remainder of the property along Riverside Drive will consist of parking
and drives that will provide traffic circulation between the Staples and the two proposed
buildings on the applicant's property. The parking is needed to satisfy the parking requirements
for both the new buildings.
The building along the Iowa River is proposed as a 5-story (six stories if the garage level is
counted) mixed -use building with 7,888 square feet of retail on the ground floor, 10,864 square
feet of commercial space on the second floor, and three levels of residential, The smaller retail
building adjacent to the Staples will include approximately 5,000 square feet of retail space.
The applicant has chosen not to use the "Good Neighbor Policy,"
ANALYSIS:
The applicant is requesting a rezoning of approximately 2.5 acres of land from
Community Commercial (CC-2) to Planned Development Overlay — Community Commercial
(OPD —CC-2). The applicant has submitted a fairly extensive narrative explaining the project.
Their stated goal is to develop a quality project that is consistent with the recently adopted
Riverfront Crossings (RFC) Master Plan and that is integrated directly with the planned west side
extension of the Iowa River Corridor Trail. In order to achieve this goal, the applicant is requesting
certain modifications to the underlying CC-2 zoning standards through the planned development
rezoning process. These requested modifications are described in more detail below.
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Consistency with the Comprehensive Plan
The subject property lies within the West Riverfront subdistrict of the Riverfront Crossings District.
The RFC Master Plan describes the existing conditions in the West Riverfront District as a "high -
traffic, auto -oriented corridor" that is "lined by commercial uses set back behind surface parking
lots. Pedestrians are typically an afterthought." The stated goals for this area of Riverfront
Crossings include:
Improve pedestrian and bicycle circulation
Capitalize on the Iowa River
Extend the riverfront trail
Temper auto -orientation
Open views and access to the river
0 Enhance the streetscape and overall aesthetics
The plan also encourages new housing in the area with destination restaurants and retail that take
advantage of the riverfront location.
The applicant is proposing two new buildings for these adjoining properties. The submitted
elevation drawings show the mixed -use nature of Building A. The applicant anticipates a
destination restaurant with outdoor seating overlooking the Iowa River and additional retail space
located south of a central open passage through the center of the building. The design allows
pedestrians to walk through the building past storefront windows that allow views into the interior
of the commercial spaces and public access to view the river from an outdoor terrace. The
applicant has indicated that they will construct the new riverfront traill along their property as a part
of their development and also extend the trail under the Benton Street Bridge to connect with the
existing trail located in Ned Ashton Park just north of the bridge.
The RFC Master Plan anticipates that newer buildings like Staples Will remain for many years, The
applicant purchased the property at 820 Riverside Drive from the owners of Staples, who placed a
number of conditions on that sale. One of those conditions is that Building B must be setback from
Riverside Drive similar to Staples. While the large front parking lot is not ideal from a pedestrian
perspective, the new building will encourage a broader mix of uses, which staff finds is an
enhancement to the site. Provided there are designated pedestrian routes between the buildings,
the riverfront trail, and pedestrian connections to Riverside Drive and Benton Street, staff finds
that the site layout is consistent with the RFC Master Plan.
Benton Street and Riverside Drive are designated uprimary" streets in the RFC Master Plan,
meaning that the buildings should be oriented toward these streets with generous storefront
window coverage to create a more comfortable and inviting environment for pedestrians. The
applicant has submitted elevation and perspective drawings of both buildings. While fairly well
developed, the details of the buildings and site still need to be refined. For example, on Building
B, given the north -facing fagade will be quite visible to customers accessing the site from Benton
Street, staff recommends that the storefront windows wrap further around the comer to make the
north -facing fagade more inviting. Additional landscaping and walkway along this wall could
screen the view of the portion of the walls that do not have windows. The applicant has also not
worked out a detailed landscaping plan or worked through details of the pedestrian routes. Staff
finds that these types of details can be resolved through the design review process and that in
general the proposed buildings and site are consistent with and will help to implement important
elements of the RFC Master Plan.
General Planned Development Approval Criteria
Applications for Planned Development rezonings are reviewed for compliance with the following
standards according to Article 14-3A of the Iowa City Zoning Ordinance. Given that the goal for is
to improve the existing substandard conditions in the area, these approval criteria should be
reviewed for consistency with the RFC Master Plan rather than trying to maintain consistency with
the existing conditions in the area.
1. The denisity and design of the Planned Development will be commilible with anoVar
complementary to a(facent development in terms of land use, building mass and scale,
relative amount of open space, traffic circulation and general layout
Residential Density — The CC-2 Zone allows a maximum of 15 units per acre. Given the site is
approximately 2.5 acres, the proposed number of dwelling units (18) is less than the maximum
allowed, so the density standard is met.
Land uses oroposed — The commercial uses proposed are all allowed in the CC-2 Zone and
are consistent with t RFC Master Plan. Residential dwelling units are allowed in the CC-2
Zone only by special exception. The City Attorney has indicated that this is not a process that
can be waived through the rezoning process. The applicant is aware that they will need to
apply for a special exception for the residential component of the project.
Traffic circulation and site layout — As noted above, the site is constrained by the existing
Staples development and the McDonald's prop". The proposed site layout integrates the
two properties together and allows traffic to circulate between them in a logical fashion. The
applicant may need to take advantage of the allowance for compact parking spaces in order to
meet all parking area setbacks, pedestrian circulation, and landscaping standards, but these
are details that can easily be worked out through the design review and site plan process. In
addition, the driveway location along Benton Street is not ideal. Closing the existing Mumm's
drive and creating a shared access point with the McDonald's would improve traffic safety on
Benton Street. However, the owner of the McDonald's property is not willing to make this
change at this time. With the goal of improving this corridor in the future, staff recommends
that at the time of final planned development plan approval, the applicant establish a cross
access easement to the McDonald's property in a manner that would allow a shared access
point further from the Benton Street bridge if and when the McDonald's property redevelops,
Staff also recommends that as a condition of this rezoning that an agreement is established
between the applicant (or any future owner) and the City to ensure that the easternmost drive
is closed once a new shared access point is established.
Mass and Scale — The mass and scale of the proposed buildings are consistent with the RFC
Master Plan, which encourages taller mixed -use, buildings along the Iowa River and building
heights in the remainder of the West Riverfront subdistrict to range between one and four
stories in height. The CC-2 Zone has a height limit of 35 feet, so the applicant has requested a
modification of this height limit through the planned development rezoning process.
Open space — There is very little usable open space in the West Riverfront subdistrict in
general. One of the goals for this district is to extend the Iowa River. Corridor Trail from Benton
Street south to Highway 6 and improve conditions along the Iowa River. The other way to
improve public open space in a highway-odented commercial area like Riverside Drive is to
improve conditions along street frontages by adding street trees and more generous parkways
between the public sidewalk and the traffic lanes and to "green" the parking areas by adding
landscaping and trees where feasible. The applicant has indicated that the success of their
mixed -use building will hinge in part on improving the conditions along the Iowa River, so they
have agreed to build the riverfront trail in conjunction with their development and to enhance
the public amenities and landscaping along the riverbank.
The applicant is also willing to dedicate 10 feet of land to the City to increase the right-of-way
along Riverside Drive, which will provide more room for green space and street trees when the
street corridor is improved in the future. The Citys capital improvements program budget
includes both Riverside Drive streetscape Improvements and extension of the Iowa River
Corridor Trail south to Highway 6. Given the constrained width of the right-of-way it will be
important for property owners to work with the City to achieve the goals of improving the street
and river corridors for pedestrians and bicyclists. The applicant has agreed to contribute to
these efforts as a part of redevelopment of this property.
2. The development will not overburden existing streets and utillifes.
All streets and utilities are available and will not be overburdened with redevelopment of this
Property as proposed,
3. The development will not adversely affect views, light and air
, property values and
privacy of neighboring properties any more than would a conventional development,
Staff believes that the proposed development will be a considerable improvement to the
neighborhood. It will provide opportunities fornew businesses and enhance property values,
views and access to the Iowa River.
4. The combination of land uses and building types and any variation from the unded)4ng
zoning requirements Or from City strVet standards will be in the public intenn% in
harmony with the purposes of this 77de, and with other building regulations of the City.
All planned developments must comply with all the applicable requirements and standards of
the underlying zoning district, unless specifically waived or modified through the planned
development process. Variations to the dimensional requirements of the underlying base zone
are allowed:
to facilitate the provision of desired neighborhood amenities or open space;
to preserve or protect natural, historic, or cultural features;
to achieve compatibility with surrounding development; or
to create a distinctive or innovative neighborhood environment for area residents.
The applicant is requesting an increase in the allowable building height in the CC-2 Zone from
35 feet to 95 feet. As mentioned above, the RFC Master Plan anticipates taller, mixed -use
buildings along the Iowa River, which will allow new housing options in the area taking
advantage of river and park views. Staff finds that the additional building height will create a
distinctive and innovative neighborhood environment for area residents. New housing above
commercial space will enhance the market for neighborhood serving retail uses on this and
surrounding properties in a manner that is consistent with the Comprehensive Plan.
Sensitive Areas Review
The applicant has applied for approval of a Sensitive Areas Development Plan to reduce the
required stream corridor buffer along the Iowa River from 50 feet to zero. The purpose of the
H
Sensitive Areas Ordinance is to permit and define the reasonable use at properties that contain
sensitive environmental features and natural resources, and allow reasonable development
while protecting these resources from damage.
The purpose of regulating development near stream corridors is to:
1) Preserve the value of stream corridors in providing floodwater conveyance and storage;
2) Promote fittration of storm water runaff,
3) Reduce stream bank erosion;
4) Protect and enhance wildlife habitat.
The Sensitive Areas Ordinance requires that a 50 foot natural buffer be maintained between
development activity and the Iowa River floodway. An applicant can request a reduction of the
required natural buffer up to 100 percent if the applicant demonstrates that all of the following
criteria are met:
1) The property is adjacent to or contains a stream corridor located in a developed area of the
city"
The subject property is located in a developed area of the City. The property contains
extensive paving and a vacant commercial building. There is very little natural area along
the Iowa River in this area.
2) The portion of the buffer being reduced does not contain other sensitive areas subject to
the requirement of this Article,
There are no other regulated sensitive features in the buffer area, but there will have to be
some grading along the riverbank and the floodway in order to construct the building and
the riverfront trail. Currently there is a mix of low quality vegetation along the riverbank.
Under the paved portion of the lot and also likely part of the riverbank is a mix of fill
materials deposited over the years due to the history of this site as a former dumping
ground. The building will have to be carefully designed and constructed to take these
conditions into account and appropriate landscaping installed to prevent stream bank
erosion and maintain the integrity of the building and the trail. The applicant's engineer is
in the process of modeling the proposed building and the riverfront trail in order to obtain a
permit from the Iowa DNR. They will need to demonstrate to the DNR that any grading or
construction will have no effect on the flood capacity of the Iowa River.
The reduction of the buffer to zero will make it necessary to shift the. alignment of the Iowa
River Conidor trail further down the riverbank. The applicant has presented a desired
location for the trail, which is above the I 0-year flood level (except where it extends under
the Benton Street bridge). The applicant has also included an illustration of an alternative
alignment of the trail that is lower than the 1 0-year flood level. They have indicated that
this alignment will only be used if necessary to receive the no -rise permit from the DNR.
City staff prefers to keep the trail above the 1 0-year flood level to the extent possible to
reduce the number of times the trail is flooded. However, given that the trail will need to be
at a lower elevation anyway to meet clearance requirements under the Benton Street
bridge, staff finds the alternative alignment would be acceptable if necessary to meet no -
rise requirements of the DNR, provided that there is an aftemative route for people to
travel across the property during times when the trail is flooded. Staff is prepared to work
through these issues with the applicant when the modeling is complete.
3) Requiring the full stream corridor buffer would preclude reasonable use of the property,
Given the site size and configuration requiring a no -build 50 foot buffer from the Iowa
7
River floodway would make development of this property difficult. In staffs opinion the
applicant has made efficient use of the site by proposing a multi -story building with
underground parking that does not hinder floodwater conveyance. In order to achieve the
amount of parking necessary to serve the commercial uses on the site and provide for
logical traffic and pedestrian circulation, a reduction in the stream corridor buffer is
reasonable.
4) Enhanced vegetative cover Will be provided in any remaining buffer area, to the extent
possible.
The applicant has indicated their intent to enhance the vegetative cover in the areas north
and south of the new building and along the new riverfront trail. However, they have not
yet developed a detailed landscaping plan, which will be somewhat dependent on the final
grading plan, design of the building, and the trail elevation. Staff suggests that the details
of the landscaping be worked out through the design review process. Plant species
should be appropriate for conditions along a riverbank and should be planted in a manner
that will enhance the stability and attractiveness of the riverbank and the public areas
along the trail.
To assess the stability of the riverbank and the underlying soil conditions, the applicant hired a
firm to conduct a geotechnical analysis of the site. The final report and a letter from a structural
engineer at Shive-Hattery, the applicants engineer for the project, is included in your packet.
At the time of site plan review and before a building permit is issued, the City will require
an analysis and certification from a structural engineer to ensure that the building and
other site work are designed in a manner that will ensure that the building is safe and the
riverbank is stabilized.
Provided that all conditions are satisfied to prevent erosion, ensure long term stability of the
riverbank, and the structural integrity of the proposed building, and that the encroachment into the
buffer will not preclude construction of the planned extension of the Iowa River Corridor Trail, staff
finds that the proposed reduction in the stream corridor buffer is reasonable.
SUMMA :
In summary, staff believes that the proposed development is consistent with the recently adopted
Riverfront Crossings Master Plan, will enhance property values, and will be a catalyst for further
redevelopment in the West Riverfront subdistrict. In addition, the project meets the goals for
capitalizing on the location next to the Iowa River and will provide better public access to the river.
Staff recommends that the final planned development plan be reviewed through the design review
process to ensure the final design of the buildings, the frontage conditions, pedestrian
connections, landscaping and other site elements are consistent with the goals of the RFC Master
Plan and meet all applicable site development standards in the zoning code,
STAFF RECOMMENDATION:
Staff recommends that REZ13-00022, a rezoning of approximately 2.5 acres of land from
Community Commercial (CC-2) to Planned Development Overlay — Community Commercial
(OPD-CC-2) for property located at 21 W. Benton Street and 820 Riverside Drive, be approved
subject to the following conditions:
1) The final design of the development and the resulting encroachment into the required
stream corridor buffer will not prevent construction of the Iowa River Corridor Trail; and
2) Prior to approval of the final planned development plan, the owner will dedicate to the City
0
of Iowa City, 10 feet of property along the Riverside Drive frontage of property at 820 S.
Riverside Drive to use for public right-of-way purposes; and
3) Prior to approval of the final planned development plan, the owner will establish a cross
access easement between the property at 21 W. Benton and the property at 804 S.
Riverside Drive (McDonald's restaurant property) at a location acceptable to the City and
will agree to close the access point to Benton Street from 21 W. Benton St. and combine
and share an access with the property at 804 S. Riverside Drive when that property
redevelops through use of the cross access easement; and
4) The applicant will present a more detailed pedestrian circulation and landscaping plan for
the site and for the areas along the Iowa River to the City for approval through the design
review process prior to issuance of a building permit. The submitted plan should show
enhanced vegetation appropriate for the location along the Iowa River, street trees, and
landscaped pedestrian routes throughout the site; and
5) The final design of the buildings and the site will be reviewed and approved through the
design review process to be consistent with the Riverfront Crossings Master Plan and
other zoning requirements.
ATTACHMENTS:
1. Location Map
2. Preliminary Planned Development and Sensitive Areas Plan
3. Geotechnical analysis
4. Supporting documents, illustrations, and written statements from the applicant, their engineer,
and architect
Approved by:
Jeff Davidson, Director of Planning
Department of Planning and Community Development
SHIVE-FIA77-ERY
October 29, 2013
The City of Iowa City
Planning & Community Development Department
410 E. Washington Street
Iowa City, Iowa 52240
RE Building Proposed Building Location
231 West Benton Street
Iowa City, Iowa
Shive-Hattery will be initiating the design of the proposed mixed use facility at 21 West Benton Street in
Iowa City, Iowa. The facility is outside of the floodway, however it remains within the 100-year
floodplain. The proposed facility will be subject to certain conditions caused by the location within the
floodplain. Shive-Hattery has professional engineers experienced with floodplain design who will be
utilized to design the foundation and structure for the facility Geotechnical information as provided by
Team Services will be incorporated in the design.
If you have questions or concerns feel free to contact our office at 319-354-3040,
Sincerely,
SHIVE-HATTERY, INC.
Steven C. Bradley, PE
Institutional Team Leader
SCB/rjm
Copy: Mark Seabold, S-H
Matt Barron, S-H
Project # 2 12245-0
Shive-HatteryInc. I 2��,34NorthgateDrive I owaC�1'/[At�2N� 1 3193�43043 : fax3193�4,6921 sni,ve-hattery,coin F
Iowa River Development, LLC
Application for Planned Development — Rezoning
November 7, 2013
Legal Description of the Property
21 W Benton Street:
THAT PART OF SW NW DISC AS AUDITOR'S PARCEL #2003115 IN SURVEY BK 46 PC 200
820 S Riverside Drive:
THAT PART OF SW NW DISC AS AUDITOR'S PARCEL #2009015 IN SURVEY BK S4 PG 133
Both parcels are currently zoning CC-2 with a combined area of +/- 2.5 Acres.
Evidence of Ownership
Riverview Development, LLC is currently in ownership of 21 West Benton and 820 S. Riverside Drive
Property owners within 300'— See attached sheet
Applicants Statement of Intent
Iowa River Development, LLC requests that the properties defined in these documents be Re -Zoned
from CC2 to CC2 with a Planned Development Overlay for I nfill Development accommodating the
recently adopted Downtown and Riverfront Crossings Master Plan and providing for the City of Iowa
City's Multi -Use trail to extend south of Benton Street to the edge of the 820 S. Riverside Drive property
This mixed -use development project is designed to take advantage of its proximity to the Iowa River.
The five (5) story building is planned to provide 8,000-10,000 square feet of retail space on the ground
floor with the expectation of having a restaurant with a dining platform extending to the east for river
views. 10,000 square feet of commercial office space will be provided on the second floor and eighteen
(18) residential units are planned for the top three floors capitalizing on views up, down, and across the
river. The apartments are envisioned to be marketed to young professionals, graduate students and
empty nesters. A portion of the roof will be developed into a roof garden space with opportunities for
community gardening, lounging and gathering spaces,
This project also includes a 4,500 square foot retail addition to the existing Staples building which is
envisioned to accommodate three separate 1,500 square foot tenants.
Parking
Parking for the residential units and some office users will be provided under the building in a secure,
floodable parking area. All other parking will be provided at grade. This under building parking area will
be designed to meet the City's requirements for a floodable structure. It will be screened from the trail
and Iowa River users by incorporating decorative steel grates, plantings, canopies and bench seating
along the building to allow the architecture of the building to extend to grade level at the riverfront
fagade and conceal the under building parking. This lower parking level will be designed to flood and
withstand the unique requirements of a floodable structure. It will also be designed with quality
materials that can be easily cleaned after a flood event.
See the attached documents that describe how the building reacts to flood events. Data on these
drawings is from the USGS National Water Information System for the Iowa River.
This project will provide space for Iowa City's proposed west side river trail with planned areas to access
the building for residents and guests. This project will also work with the City to provide access to the
Iowa River and will coordinate with the Burlington Street Dam recreation project Iowa River
Development, LILC will negotiate easement agreements with the City of Iowa City for this land.
Structure
This building will be designed to resist the unique requirements of building within the 100 year flood
plain. The structure will be designed to not only withstand the flooding effects but will be easily
cleanable should an event occur.
Reauested Variations
Building Height —Riverview Development, LLC is requesting an increase in the allowable building
height from 35 feet allowed by current CC2 zoning to a maximum of 95 feet as reflected in the adopted
Iowa Riverfront Crossings West Riverfront District. The 95 feet would accommodate underbuilding
parking, first floor retail, second floor commercial office, 3 floors of residential units, and a roof terrace.
This building height is consistent with the adopted Downtown and Riverfront Crossings Master Plan for
this site,
Floodway Buffer— Riverview Development, ILLC is requesting to reduce the flood buffer by up to 100
percent. We feel this site complies with the reduction standards within section 14-51-7 Stream Corridors
of the Iowa City Zoning Code.
1. Property is currently a "developed area" of the City,
2. Requiring the full stream corridor buffer will preclude the reasonable use of the property.
3. Enhanced vegetative cover will be provided in the remaining buffer area.
The design of 21 West Benton Street places the building adjacent to the River with parking to the west
to capitalize on the riverfront and allow vehicular access from Benton Street. The parking location to the
west utilizes the only access point from Benton Street for this property due to the Benton Street Iowa
River Bridge. The proposed building's location is based on beginning at the western site edge and
utilizing minimums for site parking and to allow for under building parking. The current 50'flood buffer
renders the site unable to reach the potential of the adopted Riverfront Crossings plan once the
projected density and parking on the site are considered,
Other Information
Existing Vegetation — The current riverfront at this property is composed of rip rap and uncontrolled
vegetation. The trees over 24" diameter at breast height (DBH) have been identified as a mixture of
Ash, Elm, Maple and Cottonwood all nearing the end of their life span or improperly cared for and
should be removed. Many understory trees (Mulberry, Boxelder, Sumac, etc.,) less than 8" DBH
situates in a messy mass between the aforementioned trees. These trees are also very poor quality in
branching habits, irregular sizes, out of control invasive shoots and all bearing little value. This project
will remove this vegetation and incorporate new sustainable plants and/ or hardscaping elements,
where applicable, for a new development vision, protecting water quality, including biodiversity, as well
as providing social benefits for tenants, visitors and the general public. The landscaping for this project
will meet the City's requirements for Landscaping.
Iowa River West Side Trail - As well as public plazas, decks and a roof garden, Riverview
Development, LLC will work with the City of Iowa City to construct the city's planned Multi -Use trail
along the west side of the Iowa River and connect it to the existing trail system north of the Benton
Street Iowa River Bridge. This project will also incorporate a riverfront plaza and pedestrian connection
from grade level at Benton Street.
The trail plan is similar to the planned trail that was approved by the DNR in 1997 which was also
planned within the Iowa River Floodway. The configuration has been slightly modified to allow the trail
to stay at a lower elevation south through the 21 W Benton Street property. Please see Trail Profile
Modifications plan C4. The trail will slope from under the Benton Street Bridge to a height above the 10
year flood plain as per the City's request. This will allow the incorporation of a "trail head" plaza for
pedestrians, bicycles, and potentially kayaks to tie into the Burlington Street Dam Modification Project.
This trail project will require DNR approval as it is in the Floodway. The DNR approval process for all
work in the Floodway is currently underway. If the DNR does not approve the trail plan at the proposed
elevation, city staff has agreed that the trail can drop in elevation to a point where it will have a no -rise
effect on the flood level per DNR requirements, given that an alternate overland path be provided
through the property from Benton Street to the south side of the property.
Closing statement
Iowa River Development, ILLC is excited to be developing this site incorporating the vision of Iowa City's
Riverfront Crossings plan. Our goal is to transform this site into a mixed -use environment that contains
dining, shopping, working and living spaces that overlook the scenic Iowa River. Tied to the downtown
via the west side river trail, we hope to provide a location for residents to live and bike to their downtown
work locations, for trail users to stop and have a bite to eat, and hopefully provide a s ' Dot for kayakers to
access the Iowa River. Iowa River Development. LLC is also pleased to add additional retail in the area
by adding to the existing Staples location.
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October 9. 1-01 1
1-1witer Comp"Irlies
1625 1 " Avenue SE
Cedar Rapids, 1A 5240"
Ann: Sareii John,3tm
Re: SU11SUrfau,, Exploration
Six Stony Buildiq,
21 West Beaton Street, 1mva City, Iowa
FEEAM Report No. 1-3 3398
Deru �vfs- Johnson:
TEAM Services
Gtowc1miciii and Constructlou Mmerlal Cmi.,Mtnuts
We have completed (11-1 SLJUSIW['�ICL�, Q'I'l)[OF-Wi011 ['01 the PYOPOSUd btli [Lljllg JJ10 ' jcCt ill ImNLI City;
Iowa. Thv �tocoriiptwying lCP011 pl',SelltS UIC flrldlll�'�S Of 111C SLIbSurfuce (�Xpluraljoli
and our I, I
YeoiechniGal recomrimidations for dusigii cwd construt�ttuji ol'builuing Foundations and
pavements
%V�- apprcciat'-�' 1.111- OpporlUllity tO bc. 01"' SCI-ViCk�, 10 �',)Ll 011 Ilk P1'QjVCL If �'011 haVC 111), questions
concerni rit 1117s [CPC)177 or ihve ol ay he of 12ul I fier set vice ;o you in nny vvny, please do net hesitate
to cont'n't w,
SilleerCly YOLPS,
--J% IV,
Is mc. Drew, 101
E,11-i�lver
Stacy G.
Brocka
14203
�tn� (I. Brocka, 111',.
Sr- GcotOLhnical Envitim
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ond )�zcr� I
Sioll mnd t1'JI I am a July �imls,d
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C.Stc i� Dcc�ml)er 3 1; 201
I'dIrUl L"I CfCJ L)\ []!IS ICII: All Pae�,
717 Sf- $tjovt - Dt,5 Moincs, 1A �0309 - ph: 18 m N: fl5-292-374 I - mail: staff @,tenjim cs.com
DQ� Wines - Furt Doduc I Spis it Lukt - Ni'la5cIii City - CeJzr Rapids - ',Vat�rloo - Davenport
Subsurface Exploration
Six Story Building - loiva City, Iov a
TEAMRepor(,Vo. 1-3398
October 9, 2013
TABLE OF CONTENTS
PROJECT INFORMATION ......................................................
SITE CONDITIONS ..................................................................
FIELD EXPLORATION ............................................................
LABORATORYTESTING .......................................................
Natural Moisture Content ......................................................
Unconfined Compressive Strength ........................... : ...........
Bedrock Unconfined Compressive Strength .........................
Percent Core Recover) ..................................................... _ ...
Rock QUalitv Designation (RQD) .............. _ .........................
1� I I Rq I fRV A CV [ON �Z
SoilProfile .................................................. .................
Groundwater Level Observations ..................................
CONCLUSIONS AND RECOMMENDATIONS ............
Existing Fill Considerations ..........................................
Site Preparation and Grading ........................................
DeepFoundations ................................................ .........
hitermediate Foundations ..............................................
Lateral and Uplift Force Resistance ..............................
Site Classification for Earthquake Design ....................
FloorSlabs ....................................................................
Permanent GrOUnchvater Conti -of ..................................
Lateral Earth Pressures, .................................................
I 'emporary Excavation Support ....................................
Cut and Fill Slope StabilitN Considerations ..................
Construction Groundwater Control .......... ....................
Site Surface Drainage ....................................................
Pavement Subgrade Preparation ....................................
Pavement'] hicknesses ... ..............................................
QUALIFICA HON OF REPORI . ......................................
APPENDICES
FIGURE No. 2
BORING PLAN
LOGS OF BORING Nos. 1, 1 A, I B, 2, 3, 3A, 4A and 5
SUBSURFACE PROFILES (SP-I and SP-2)
MFIED SOIL CLASSIFICATION SYSTEM
GENERAL NOTES
TEAM Services
I ........ I .........................................
...................................................
..... I ................. I ...........................
................................................... 2
......................................................
......................................................
. -
16
......................................................
17
..... I .... I ...........................................
17
....... I ..... .... I ..... I ........
..................... 17
......................................................
is
.......... 1. ..........................
I ............... 19
................... ..................................
20
Subsurface Exploration TEAM Services
Six Story Building - Iowa Citj� lowa
TE,41tReportNo. 1-3398
October 9, 2013
PROJECT INFORMATION
Project information has been provided bN Ms. Saren Johnson of Hunter Companies in telephone
and email correspondence with our Mr, Isaac Drew. P.E. Included �N ith the email was a site plan
showing the proposed building and boring locations. The project will include construction of a
new six -story retail/office building with lower level parking at 2 1 West Benton Street in Iowa City,
Iowa. The building will reportedly be constructed with steel and precast plank and a glass fa�ade.
Maximum column loads of 1200 kips are anticipated. Main level finished floor elevation will be
at 652.0 feet and the lower level elevation will be at 642.0 feet. The ground surface elevations of
our borings �� ere interpolated from the Shive f fatten, contour plan provided to our office.
SITE CONDITIONS
This site current1v has an existin.o building. pavements, tress and vegatation. The Iowa River lies
to the east of the site. A ma ority of the site slopes gently downward from north to south with a
relief of about 5 feet. The cast side of the site slopes downw,aid sharply towards the river with a
relief of about I I to 12 feet,
FIELD EXPLOI�ATION
A total of 5 borings were originall) laid out on site by Shive I [atter� personnel. Borings I through
4 were relocated from there ori-inal locations due to difficult drill rig access. Borings I and 4 were
redrilled (Boring,s IA and 4A) due to deeper depths to bedrock that Nvere not anticipated. Boring
I was redrilled a second time (Boring I B) due to difficulty drilling Boring ]A. Boring 3 was
redrilled (Boring- 1A) due to early auger refusal in cobbles and boulders. The ground surface
elevations were determined by interpolating between Contours in a Shive Hattery site plan
provided by the client. The locations and elevations of the borim,s should be considered accurate
only to the degree implied by the means and methods used to define them.
Our drilling equipment consisted of a truck-MOUnted auger drill rig. The borings were made by
mechanically twisting a Continuous flight hollow stein steel auger into the soil. At assi&ne�
intervals, the center drive bit of the auger was removed and soil samples NNere obtained. At the
completion of each boring the water levels were obtained and were backfilled with soil auger
cuttings. Where applicable, pavements were patched with concrete.
Representative samples were obtained Usim, a split -barrel sampling procedure in general
I
accordance with ASTM Specification D 1586. In the split -barrel sampling procedure, a standard
2-inch O.D. split -barrel sampling spoon is driven into the ground with a 140-pound hammer falling
Page I of 21
Subsurface Exploratiun
Six Story Building - Iowa Cily, Iowa
TEAMReporffo. 1-3398
October 9, 2013
TEAM Services
a distance of 30 inches. The number of blows required to advance the sampling spoon the last 12
inches of a normal I 8-inch penetration is recorded as the standard penetration resistance value.
These values are indicated on the Boring togs at the depths of occurrence. The samples were
tagged for identification. sealed and returned to the laboratory for testing and classification.
Ali automatic harnmer ),�aS used to perform the Standard Penetration 'tests in the borin.-s. In the
automatic hammer system. the cathead and rope used traditionally in the manual test procedure is
replaced with all automatic lifting inechanisin for the 140 Pound driving weig-ht. The reduction in
system friction with tile automatic hammer systein results in a significant increase in the driving
energies. This results ill Si�llifiCalltly greater driving efficiencies and a corresponding decrease in
the number ofbloNN s in the Standard Penetration Test results. \Ve have taken the driving efficiency
of the automatic haminer system into account when analyzing this data.
Field logs of the borings were prepared by the drill crew. These togs included visual classifications
of the materials encountered during drilling, as well as the driller's interpretation of the subsurface
conditions beween samples. Final Boring Logs included with this report represent an
interpretation of the field logs and include modifications based on laboratory observation and test
of the samples.
LABORATORY TESTING
Based on the driller's field records and examination of the samples in the laboratory, a soils testing
program was developed to collect more information about the soil conditions at the site. The
following is a brief description of the specific tasks completed for this project.
Natural Moisture Content -- fhe natural moisture content of selected samples was determined in
general accordance �N ith ASTM 1) 2216. f lie moisture content of the soil is the ratio, expiessed as
a percentage, of the weight of water in a given mass of soil to the NNeight oftlic soil particles. The
results are presented on the Boring Logs at the depths from NN hich the samples were obtained.
Unconfined Compressive Strength -- A calibrated hand penetrometer was used to estimate the
approximate unconfined compressive strength of selected cohesive soil samples. The calibrated
hand penetrometer has been correlated with unconfined compression tests and provides a better
estimate of soil consistency than visual examination alone.
Bedrock Unconfined Compressive Strength -- Selected bedrock samples obtained from the
bedrock cores were tested in the laboratory to determine their unconfined compressive streng-th in
general accordance " ith ASTM D 2938. The samples were prepared in general accordance with
Page 2 of 21
Subsurface Exploration
Six Story Building - Iowa City, Iowa
TF,WReportNo. 1-3398
October 9, 2013
TEAM Services
ASTM D 4543 where the samples were cut such that the height is approximately 2 to 2.5 times the
sample diameter of the sample. After the samples were trimmed, they were capped with capping
compound and then placed, without any confinement, in a triaxial load frame and tested for
compressive strength with a controlled rate of strain. The peak stress on the samples, in psi, are
reported on the Boring Logs at the depth from which the samples were obtained,
Percent Core Recovery —The percent core recovery is the ratio of the length of the core recovered
after coring to the total length of the core run. The results of out percent recovery calculations are
presented on the Boring Logs at the appropriate sample depths.
Rock Quality Designation (RQD) -- The RQD is a measure of the quality of the rock mass, The
ratio of the total length of intact bedrock samples larger than 4 inches in length to the total length
of the core ran is termed the bedrock's RQD. Tle RQD is also often expressed as a percentage.
The results of our RQD calculations are also presented on the Boring Logs at the appropriate
sample depths.
As part of the testing program, the samples were classified in the laboratory based on visual
observation, texture and plasticity. The descriptions of the soils indicated on the Boring Logs are
in accordance with the enclosed General Notes and the Unified Soil Classification System.
Estimated group symbols according to the Unified Soil Classification System are given on the
Boring Logs. A brief description of this classification system is attached to this report.
SUBSURFACE CONDITIONS
Soil Profile
Subsurface conditions encountered during this exploration are indicated on the individual Boring
Logs. Based on the results of the borings, subsurface conditions on the project site can be
generalized as follows,
Borings were drilled through the existing asphalt pavement in Borings 1, 3 and 5. The pavement
consisted of 4 to 6 inches of asphalt and an additional 6 inches of concrete beneath the asphalt in
Boring 5.
Fill was encountered beneath the pavements, and at the ground surface of Borings 2 and 4 and
extended from 5 Y2 to 10 Y2feet below existing grades. The fill consisted of variable materials such
as crushed limestone, sandy lean clay, lean clay, silt and fine to medium sand with various
concentrations of sand, gravel, brick, concrete, asphalt, glass, iron pipe and cinders. The thickest
Page J of 21
Subsurjace Exploration
Six Story Building - Ioi4 a City Iowa
TEAM Report Alo. 1-3398
October 9, 2013
TEAM Services
fill section of I 0'/2feet below existing grade was encountered in Boring I near the north side of the
proposed building.
Alluvial deposits were encountered beneath the fill. These materials were like1N deposited by the
nearby lw�a River and consisted of medium stiff sand) sill cohesive soils and very loose to
extremely dense fine sand, fine to mcdiLlIll sand, silt) sand. clayey sand, inediturl to coarse sand,
sandy gravel and gravelly sand granular soils. W here sam pled, the Ill ickness of the al hivium varied
from 41 '/2 to 611/2 feet thick in the boriiiLs and extended to about 48!/2 to 67 feet below existing
grades.
Beneath the alluvial deposits, soils derived from ancient glacial activity were encountered. I'liese
materials, which are usualIv called glacial tills. are unsorted soil deposits derived from continental
glacial ice sheets present in this area )cars ago. These soils have nearly equal components of sand,
silt and clay. but the clav fraction dominates their engineering properties. ]'race quantities of
gravel and larger materials are also usuall� present. The glacial tills at this site contained very stiff
to very hard lean clay. sandy lean clay and sand) silt. Glacial ouINN ash layers are also common
within glacial till deposits. Glacial outwash Occurs when glacial drift has been sorted and
deposited by &facial nieftwater streams. This usually deposits layers of vvell p-aded sand. and
sometimes sand and gravel, but is dependent on the flow velocities of the inellwater streams. The
glacial outwash deposits at the site occurred as medium dense to extreniel\ dense fine to medium
sand and sand), gravel. Cobbles and boulders �Ncrc also noted in our borings (Borings 2, 3 and 3A).
It is common to encounter these materials within glacial till deposits. I he possibility of their
presence should be considered �Nhere excavations or gradin., operations at this site advance down
into the glacial till soils. Where sampled, the glacial deposits extended to about 49 and 80 feet
below existin.- grades. Borings 2, 3 and 3A were terminated to auger refusal in the cobbles and
boulders at about 49 to 60 feet below existing grades.
Beneath the (,,facial deposits in Borings I B, 4� 4A and 5, weathered or unweathered bedrock was
encountered. A lesser degree of bedrock NNeathering and soil formation are exhibited with
increasing depth. Belo'A' the severicy weathered zone is a moderately or slightly NNeathered zone
of the bedrock vhich. in turn, overlies the unweathered bedrock (as observed by the limestone
cored in the aforementioned borings). The weathered bedrock in Boring 4 consisted of severely
weathered moderately hard to hard limestone bedrock. -1 hese borings terminated in the bedrock
near depths of 78 to 98 feet below existing grades.
The above descriptions provide a general Summary of the subsurface conditions encountered. The
attached Boring Lo,s contain cletai led information recorded at each boring location. These Boring
Logs represent Our interpretation of the field to,,,s based oil engineering examination of the field
samples. The lines designating the interfaces between Various strata represent approximate
Page 4 of 21
Subsurface Exploration
Six Story Building - Iowa City, Iowa
TEAM Report No. 1-3398
October 9, 2013
TEAM Services
boundaries, and the transition between strata may be gradual. It should be noted that the soil
conditions will vary between the boring locations. The generalized Subsurface Soil Profiles
(Figures SP-1 and SP-2) is presented in the Appendix depicts the relative deposit elevations in the
borings.
Groundwater Level Observations
The borings were monitored during and shortly after drilling operations to detect moisture seepage
and groundwater accumulation. The results of our water level observations are noted on the
Boring Logs enclosed in the Appendix. Groundwater accurnulation was observed during drilling
at depths of 23 to 28 feet below existing grades in Borings I through 5,
Fluctuation of groundwater levels can occur due to seasonal variations in the amount of rainfall,
runoff, surface drainage, subsurface drainage, site topography, irrigation practices, ground cover
(pavement or vegetation), and other factors not evident at the time the borings were conducted.
Normally, the highest groundwater levels occur in late winter and spring, and the lowest levels
occur in late summer and fall. The fluctuation of the groundwater levels should be considered
when developing the design and construction plans for this project.
CONCLUSIONS AND RECOMMENDATIONS
Existing Fill Considerations
Fill was encountered in all of the borings and extended from 51/2to 10 V2 feet below existing grades
across the site. The fill consisted of variable materials such as crushed limestone, sandy lean clay,
lean clay, silt and fine to medium sand with various concentrations of sand, gravel, brick, concrete,
asphalt, glass, iron pipe and cinders. Based on the limited tests conducted within the fill, it appears
that the fill consistency ranges from poorly to moderately compacted.
The poorly compacted existing fill and/or unsuitable fill materials (brick, concrete, iron pipe, glass
and cinders) were encountered at the all areas explored. It is our opinion that the existing fill in
these areas is not suitable for support of structures. All existing fill that is removed should be
replaced with suitable, compacted and tested engineered fill material, Some of the existing fill
appears suitable for reuse as engineered fill; however, the existing fill would have to be properly
sorted prior to reuse.
Since we will be recommending intermediate or deep foundations for the building, which will
extend beyond the stated depths of fill, the primary concern is the fill's ability to properly support
Page 5 of 21
Subsurface Exploration
Six Story Building - Iowa City, Iowa
TEAMReportNo. 1-3398
October 9, 2013
TEAM Services
building floor slabs. Without any information or background on the fill placement, there is an
inherently high risk of variability and uncertainty associated with the support capabilities of the fill
in its present condition. Supporting slabs on undocumented fills could cause distress to the floor
slabs and to eliminate the risk associated with the fill, it will be necessary to remove the fill and
replace it with suitable engineered compacted and tested fill material. Where it is determined that
over -excavation would not be the most economical or practical solution to mitigate the unknowns
within the existing fill, we recommend the floor slab instead be designed as a structural slab
supported above -grade on a deep foundation system, used to support the structure, or supported
on -grade by an intermediate ground improvement system such as Geopierst or stone columns. If
the slab is designed to be supported by an intermediate ground improvement system, then we
recommend that a minimum of 12 inches of crushed rock be compacted underneath the slab for the
building, to allow for more uniform slab support.
If the owner is willing to assume the risk of possible movements of the surface parking pavements,
the existing fill could be left in place beneath the pavement sections, If the existing fill is left in
place in the pavement areas, we recommend that extensive observation and testing of the fill be
conducted during construction to further evaluate the suitability of the existing fill. Where
unsuitable soils are encountered during this process, we recommend that the unsuitable soils be
over -excavated and replaced with engineered compacted fill, It should be noted that due to the
limited depth and extent of hand probing to be conducted, that not all deficient zones may be
detected during this process. As a minimum, the parking subgrade should be prooftolled. If the
existing fill is left in place beneath the surface parking areas, it may be beneficial to utilize hot mix
asphalt since it is easier to patch and/or repair.
Contract allowances should be made for some remedial work at the site related to subgrade
preparation construction, This may include over -excavation and backfilling of unsuitable soils
encountered at subgrade elevation excavations in accordance with the recommendations of this
report. The amount of such work cannot be defined at this time; therefore, the owner should be
informed of these cost variables.
Site Preparation and Grading
Demolition of existing structures should be performed along with the associated foundations and
fill. Any underground utilities present in the area of the proposed building, which are to be
abandoned, should be removed along with their associated backfill material. Consideration should
be given to rerouting any existing utilities which will remain in service to locations outside the
planned building so that they will be easily accessible for maintenance. Also, removal of the
existing fill will also be required as discussed in the previous Existing Fill Considerations section,
Any utility backfill or existing fill removed are to be replaced with engineered compacted fill
Page 6 of 21
Subsurface Exploration
Six Story Building - Iowa City, Iowa
TEAMReportNo. 1-3398
October 9, 2013
TEAM Services
which meets or exceeds the Class I Construction Application requirement in the following Table
A, Where trees are cleared, the stumps should be excavated and removed. Construction debris
should be removed from this site and lawfully disposed or recycled.
We expect that minor Cut with main[) fill sections being required to achieve the desired final
grades for this project. Site preparation should continue with the removal of any organic -laden
soils, vegetation and any loose, soft, or otherwise unsuitable materials. 'I lie site strippings and any
near surface soils w ith organics could be used for landscaping purposes in rion-critical areas where
support for floor slabs and pavements is not required.
After stripping and removal, the exposed grade should be prootrolled and inspected by TEAM
Services personnel. Prooft-olling should be conducted Nvith a fully loaded tandein axle dump truck
having a inininIUM gross weight of 25 tons. Anv unsuitable soils identified during this process
should be removed and replaced with suitable engineered compacted and tested fill which meets
or exceeds the Class I Construction Application requirement in the following Table A.
TABLE A
RECOMMENDED DEGREE OF CONIPACTION GUIDELINES
Standard
Standard
Relative Density
Proctor
(ASTM D4253
Construction Application
Proctor
(ASTM D698)
& D4254)
(ASTM D698)
Cohesive Soil
Cohesionless
less
Cohesionless
il
Soil
soil
Class I
Prepai ation,fill tot building slabs, pavements and
95%
98%
70%
other critical backfill at eas
Backfill adjacent to structures not supportin,
Class 2
other slabs or pavements.
90%
93%
45%
Minor Subsidence possible.
Class
Backfill in non -critical areas.
85%
88%
20%
Moderate subsidence possible.
(Jse Relative Density technique (ASTM D4251 & D4254) where Standard Proctor technique (ASTM
D698) does not result it) a definable maximum dry density and Optimum moisture content.
Care should be taken to prevent Uunecessary disturbance Of SUbgrade soils. Disturbed areas should
be removed and replaced NN ith engineered compacted fill in accordance Nvith the recommendations
of this report.
Fill and backfill placed for support of the proposed structures should consist of approved niateriuls
which are free of organic matter and debris. Brick, concrete, rocks or other solid pieces with a
Page 7 of 21
Subsurface Exploration
Six Story Building - Iowa City, Iowa
TE,4MReportNo. 1-3398
October 9, 2013
TEAM Services
maximum dimension of 3 inches or larger should not be placed in the new fill. We recommend
that low -plasticity cohesive soil or granular material be used for general fill placement. By our
definition, low -plasticity cohesive soil would have a liquid limit less than 45 and a plasticity index
less than 25. In our opinion, some of the on -site soils appear to meet these criteria and can be used
as new engineered compacted fill. Some sorting, however, will be required in the existing fill.
Any off site potential borrow materials should be evaluated by TEAM Services prior to their use
as engineered compacted fill.
Table A lists recommended minimum compaction requirements for cohesive and coliesionless fill
materials for specific applications. For non -expansive cohesive soils, moisture contents within a
range of -2 to +3 percent of the material's optimum moisture content (as determined by Standard
Proctor ASTM D 698) are necessary to achieve the desired fill qualities for general grading and
utility backfill while granular material should be placed within 3 percent of the material's optimum
moisture content.
The on -site soils can be excavated utilizing conventional excavation equipment. However, larger
excavation equipment may be required depending upon the size of the rubble that may be
encountered within the existing fill. Materials should be compacted in loose lift thicknesses not
exceeding 12 inches and at a thickness that is compactable with the compaction equipment being
utilized. Compaction of granular material can generally be suitably compacted with vibratory
compaction equipment. Proper compaction of cohesive soils can be achieved with sheepsfoot or
pneumatic type compactors within the above moisture content ranges. Sufficient density tests
should be performed on each lift of engineered compacted fill placed to verify that adequate
compaction is achieved.
Deep Foundations
Based on the test boring data, the existing fill and native overburden soils encountered at this site
would not be capable of supporting the anticipated heavy structural loads for the proposed 6-story
building. Therefore, in our opinion, a deep foundation system consisting of either drilled shafts
(auger cast piles or drilled caissons) or steel H-piles embedded into the limestone bedrock will
provide reliable support for the proposed structure. The limestone bedrock was generally
encountered in the building borings (Borings 1B, 4A and 5) from elevation 566A feet to 569,5 fect,
The following sections provide further detailed design information for these two foundation
systems.
It should be noted that based on the difficulty drilling through cobbles and boulders on the east side
of the site (Borings 2, 3 and 3A), where auger refusal was encountered, we anticipate that
construction of drilled shafts may not be feasible or may be very difficult. Further, the deep depths
Page 8 of 21
Subsurface Exploration
Six Story Building - lon a 00,, Iona
7EAMReportA'o. 1-3398
October 9, 2013
TEAM Services
of sand deposits vvill make the construction of drilled caissons difficult, requiring the use of casing
and slurry. Therefore, it is our opinion that the support of the building on either steel H-piles or
intermediate foundations may be a more practical and economical approach.
Drilled Sbafts
The follcvNing 'Table B presents the allowable skin friction values at different elevation intervals
fordrilled shafts (au,-er cast piles and drilled caissons), generally based on the soils encountered in
our borings. Separate end bearing values are also presented for either auger cast piles bearing in
practical auger refusal in limestone bedrock and drilled caissons embedded in limestone bedrock.
Uplift reactions due to Overturning loads can be resisted by skin friction and buoyant weight of the
concrete foundation. We recommend that skin friction Values for uplift be limited to 70 percent of
the downovard skin friction values ill the Table B. Please note that the skin trictionand end bearing
capacity values provided include a safety factor of at least 2.
'TABLE B
DRILLED SHAFT PARAMETERS
Allowable Skin
Allowable End
Soils (Elevations)
Friction Value
Bearing Value
(PSf) 3
(pst)
Existing, Fill
(Elevation 642.0 to 639.0 feet)
Neglect
Neglect
Overburden Native Soils
(Above Elevation 610.0 feet)
125
Neglect
OverblArden Native Soils 4
BeloNN Elevation 610.0 feet)
375
Neglect
Practical Auger Refusal in Limestone
Bedrock
--
80.000
Limestone Bedrock 6 1
10,000 2
1 w000 I
I . Rcquires mininium 3 feet Penetration into this straturn to obtain this bearing capacity (Drilled Caissons).
2. When end bem m- is Litili/ed, ou recommend skin friction be i-nored for at least t shaft diameter abo� e the
bottom of the shalt,
3, For uplift resislan", 70% ofthe available skin 1i iction ma� he considei ed applicable. I he contribution of the
upper 3 Icet of eaQli soil straturn to uplift resistance should be considered at the same value as the soil
immediately abo�c it.
4. The native soils in this stratum includes "cathered limestone bedrock
5. For Auper Cast Piles Only
6. For Drilled Caissons Only
Page 9 of 21
Subsurface Exploration
Six Story Building - Iowa City, Iowa
TEAMReport,Vo. 1-3398
October 9, 2013
TEAM Services
Drilled caissons or auger cast piles should be located no closer than 3 shaft diameters (3B), center
to center, before reductions need to be implemented for vertical capacities. A group reduction
factor of 0.7 should be applied to piles that are installed between 3B and 2B. We recommend that
piles not be installed less than 2B.
With deep foundations installed as described in this report, we estimate long-term total settlement
due to structural loads v, ill be less than '12 inch and differential settlement may be less than '/2 of the
total settlement.
A buoyant soil unit NNeight of 55 pcf should be used for sustained loading conditions. while a total
unit weight of 120 pcf may be used for transient loads, Group action for lateral resistance ofdrilled
shafts should be taken into account when spacing is less than 8 diameters (center to center). If
spacing is less than 8 diameters, then the following reduction factors in Table C should be utilized.
TABLE C
GROUP REDUCTION FAcTORS FOR LATERALLY LOAD DRILLED SUAFTS
Shaft Spacing (Diameters, D)
Reduction Factors
8D
1.0
61)
0.7
41)
0.4
3D
0.25
The contractor should be aware of the soil and groundwater conditions which may be encountered
during drilled caisson shaft installation. Based on variabilitv of the existing fill, and with granular
soils being encountered at this site, caving of the existin" fill 111m occul while cavina of the
granular soils will likely occur into the drilled caisson shaft excavations. therefore, temporary
casing or skjrr� drilling methods will be required to complete drilled caisson shaft excavations.
When casing is removed during concrete placement, care should be exercised to maintain concrete
inside the casing at a sufficient level to resist earth and hydrostatic pressures present on a casing
exterior. The use of slurry drilling should be performed only by a contractor experienced with
these procedures. Care should be taken So that the sides and bottom of the shaft excavations are
not disturbed during construction. I land cleaning ofthe drilled shaft bottoms v� ill not be required
if the drilling tools are capable of rernoviin, soft or loose fragments and provide a plane hearing
surface.
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Subsurface Exploration
Six Story Building - Iowa City, Iowa
TFAMI?epori,ko. 1-3398
October 9, 2013
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Concrete should be placed as soon as possible after the drilled caisson shaft excavation has been
completed to the confirmed bearing level and the bearing surface has been cleared of loosened
material. Concrete should not be placed in drilled shaft excavations without tremie where the
depth of water exceeds several inches. The concrete should have a slump of 5 to 7 inches at the
time of placement. Concrete slump during slurry construction should have a slump of 7 to 9 inches.
Concreting procedures in the American Concrete Institute recommended practice ACI 306, as
currently revised, should be carefully adhered to,
Auger cast piles are to be grouted without interruption and a positive grout pressure should be
maintained, at all times, during the grouting operation. Reinforcing, when required, should be
installed immediately after the grout is placed and is still fluid. During the construction of the
auger cast piles, two adjacent piles should not be installed or grouted on the same day. This is to
avoid the grout from migrating to the adjacent piles. If adjacent auger cast piles are poured on the
same day, we would recommend a minimum edge-to-cdge distance of 5 feet between piles.
The deep foundation depths may require adjustment in the field depending upon conditions
encountered at the time of construction, Therefore, we recommend that installation of all of the
deep foundations be observed by a geolechnical engineer or his technical representative from
TEAM Services to determine that design bearing conditions have been achieved, to note changes
in the foundation materials, and observe construction procedures.
The base of pier caps and grade beams should extend a minimum of 3V2 feet below the lowest
adjacent exterior grade to avoid frost heave effects.
Steel H-Piles
Steel H-piles may be designed for approximately 25% of the H-pile yield strength which is
typically 50,000 psi. We recommend using an end bearing value of 9,000 psi for pile sizing. The
piles should be organized in groups with a typical center to center spacing of 3 times the pile width.
If spacing is less than 8 diameters for lateral load considerations, then the reduction factors given
in Table C should be utilized.
Rock "shoes" (point reinforcement) will be required for the piles to protect the piles in hard
driving. It should be noted that some pre -drilling may be required to advance the piles through the
fill where extensive rubble may be encountered. Consideration of corrosion of the pile should be
taken into account when designing the pile, such as corrosion resistant pile, painting the pile, using
other corrosion inhibitors, or using a slightly larger pile than designed.
Page I I of 21
Subsurface Exploration
Six Story Building - Iowa City, Iowa
TEAMReport-Vo. 1-3398
October 9, 2013
TEAM Services
Use of a Pile Driving Analyzer is recommended to verify pile capacity instead of a load test.
Configuring a full-scale load test at this site is anticipated to be difficult because of the primarily
end -bearing nature of the piles and difficult in obtaining adequate uplift resistance in the reaction
piles. Production pile capacities Should be established using the xvave equation. TEAM Services
should be retained to inspect the pile installation.
Intermediate Foundations
An alternative to the deep foundation options would be to use in intermediate foundation system
(such as stone coluirms or Geopiers") to support the building. These are patented foundation
systems designed by licensed contractors who have a protessional engineer oil staff. We
recommend that the stone COhnnu or Geopier" C011SUItant be provided a copy of this report to
determine requirements for additional exploration, if any. to support their design x�ork. The
foundation contractor should submit his proposed solution to FLAM Sen ices for review. 'typical
intermediate foundation designs utilize allowable bearing capacit�, on the order of 4,000 to 6,000
pounds per square foot.
Lateral and Uplift Force Resistance
Deep foundations for structures will be subjected to some lateral and uplift forces. -1 he foundations
should be sized to resist these anticipated forces without excessive deflection and displacement.
Lateral forces on the concrete w i I I be resisted bN the friction betNN een the base of the f0tindati on
and the underlying soils and passive earth pressures. A coefficient of 035 could be reasonably
LISSUMed for evaluating ultimate frictional resistance to sliding at the foundation -soil contact. This
coefficient should be used with ininirrulin dead load Lis the normal force. A passive earth pressure
coefficient of 3) could be reasonably assumed for evaluating ultimate lateral resistance ofthe soil
against the side ofthe foundation where this is apermissible condition. I his passive earth pressure
should be divided by a safety factor ofat least 2 to limit the amount of lateral deformation required
to mobilize the passive resistance. The contribution to passive resistance of the frost affected
materials in the Lipper 3 V2tcetatthe site should be limited to solel\ the weightofthis soil. This can
be accomplished by modeling this depth of soil as a uniform sUrchargoe load equivalent to the
weight of the soil in the analysis.
Uplift resistance M11 be provided by the minimum dead weight of the structure and the foundation
elements, Plus the weight Of the soil above the foundations. The weight of the soil above the
foundations and extending outward at a 2 vertical to I horizontal slope may be considered as
contributing to the uplift resistance of the foundations. This is based on (he assumption that the
Page 12 of 21
Subsurface Exploration
Six Story Building - Iowa Cilj� Iowa
7EAMReportNo. 1-3398
October 9, 2013
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backfill of the foundations will be compacted in accordance with the recommendations of this
report for structural fill.
As previously mentioned, the buoyant unit weight of the soils should be used to calculate the
lateral and uplift resistance for Sustained loads. while the soils' total unit weight may be used for
transient loads Such as wind loads. A buoyant unit weight of 55 pcf and a total unit weight of 120
pcf may be used on a] I soils.
Site Classirication for Earthquake Design
Based on the information fi-orn the Borings Logs and calculations conducted per the International
Building Code. ��e have concluded that Site Chss D" should be used for seismic design of the
proposed buildin(,.
Floor Slabs
As mentioned in the Existing Fill Considerations section we have recommended that the floor
slab for the building be designed as a structural slab Supported above -grade on a deep foundation
system, or supported on-&radc by an intermediate ground improvement system such as GeopiersR
or stone columns.
In order to allow successful use of a variety of floor systems, measures to control vapor
transmission through floor slabs placed on grade are recommended where moisture sensitive floor
coverings are a possibility. This would include use of a vapor barrier/retarder with a minimum
thickness of 10 inils placed between the slab and all underlying capillary barrier. The vapor
barrier/retarder should be strom, enough to resist pUnCtUring of capillary barrier materials.
We recommend that a capillary barrier of clean manufactured sand or crushed limestone (drainable
material) be provided bew cen the vapor barrier/retarder and underlying fill. The capillary barrier
should be at least 4 inches thick and contain less than 6 percent material finer than the U. S. No.
200 sieve.
Below -grade floor slabs �� ill be subject to the influence of groundwater. The following section
discusses permanent groundwater control.
Permanent Groundwater Control
Groundwater was encountered in the borings drilled at this site. For design purposes, the
maximum ,roundwater level at the site should be considered to be within a few feet of the ground
Page 13 of 21
Subsurface Exploration
Six Story Building - Iowa City, Iowa
TEAMReportNo. 1-3398
October 9, 2013
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surface elevation. A permanent groundwater control system which provides positive drainage for
the below -grade structures is recommended to prevent development of hydrostatic pressures
against the below -grade structures and protect the lower level from excess subsurface moisture
seepage. If wall drains are not provided, then the design groundwater elevation should be
considered equal to the ground surface and undrained earth pressures would apply for lateral earth
pressures.
Floor slabs which are placed below surrounding grade should be provided with a under floor
drainage system to protect the floors from hydrostatic uplift forces. The under floor drainage
system should consist of a minimum of a 4-inch thick drainable material hydraulically connected
to trenches filled with drainable material and a 4-inch diameter perforated pipe. The trenches
should be spaced of approximately 30 feet on center. Drainable materials placed in the trenches
should contain less than 3 percent material finer than the U.S. No. 200 sieve. Drainable materials
placed in the layer between the floor slab and the trench should be crushed limestone containing
less than 6 percent material finer than the U& No. 200 sieve. The perforated pipes should be
designed to collect water from the drainable material and be sloped to drain to a reliable gravity
outtall. The flow line elevation of these pipes should be at least 12 inches below the final subgrade
elevation of the floor slab. The perforations in the pipe should be sized to keep the drainable
material out of the pipe. For the size of aggregates recommended, either 3/8-inch diameter
perforations or 1/4-inch width slots or smaller should provide adequate performance. Where slots
or perforations are concentrated on one side of the pipe, the pipes should be oriented with the
perforations or slots on the bottom side of the pipes. The radial thickness of drainable material
around the pipes should not be less than 4 inches.
A perforated rigid plastic or metal drain line installed behind the base of walls extending below
adjacent grade is recommended to prevent hydrostatic loading on the walls (and/or seepage into
below -grade building levels). The invert of a drain line around a below -grade building area should
be below the finished subgrade elevation of the interior floor, The drain line should be sloped to
provide positive gravity drainage and should be surrounded by free -draining granular material
containing less than 3 percent material finer than the U.S. No. 200 sieve graded to prevent the
intrusion of fines, or an alternative free -draining granular material encapsulated with suitable filter
fabric. At least a 2-foot wide section of firee-draining granular fill should be used for backfill above
the drain line and adjacent to the wall and should extend to within 2 feet of final grade, The
granular backfill should be capped with 2 feet of compacted cohesive fill to minimize infiltration
of surface water into the drain system. See Figure No. 2 enclosed in the Appendix for typical cross
sections,
A prefabricated drainage structure may be used above a drain line and the surrounding filter
materials as an alternative to free -draining granular fill. A prefabricated drainage structure is a
Page 14 of 21
Subsurface Exploration
Six Story Building - lobu 00), Ioiva
TFAMReportiVo. 1-3398
October 9, 2013
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plastic drainage core or mesh which is covered with filter fabric to prevent soil intrusion, and is
fastened to the wall prior to placing backfill.
Below -grade walls which adjoin Occupied areas should be protected with a moisture resistant
barrier material oil the outside of the wall. Care Should be taken during- wall backfilling operations
to avoid damaging the moisture resistant material.
All drain lines should be directed to flow by gravity to a reliable, trost-firce outfall if sufficient
topographic relief is available at the site. A sunip pit and pump should otheroise be constructed
for the beloNN-grade facility.
Lateral Earth Pressures
The project below-,-rade walls or retaining walls must be capable of resisting the lateral earth
pressures due to the unbalanced soil heights. Therefore, the walls should be designed to
accommodate these unbalanced lateral soil pressures. The following Table D lists the estimated
lateral earth pressures for cohesive and cohesionless (granular) backfill.
Cohesionless (granular) backfill lateral earth pressure parameters may be used where granular
backfill has a ruillialUrn width of 2 feet and be NN ide CDOUgh to accoirlmodate the back slope limit
line of 2:1 (vertical to horizontal) or flatter in accordance with Figure No. 2 enclosed in the
Appendix. The area betAeen the required minimum zone ot'granular material and the actual limits
of excavation may be backfilled with either cohesive or goranular soils. The "ranUlar material
should be a free draining material (less than 3 pet -cent passing the U.S. No. 200 sieve) and
hydraulically connected to a Suitable drainage system. Ali acceptable drainage system may be
constructed using perforated rigid pipe encased in coarse clean granular inaterial graded Such to
prevent the intrusion of fines or an alternatiN e free draining g-ranular material encapsulated with a
suitable filter fiabri C. Fhe drain lines should be sloped to provide positive gravity drainage to a
Suitable Outlet such as a sunip pump. a storin drain, or frost -free OLIffilll if sufficient topographic
relief is available at the site.
Ifthe top of the wall is able to deflect approxirnatcl� 0.2% to 0,4% of the wall heig-lit, then active
earth pressures can develop with granUlar backfill. Ho"ever. if the NNall is ri,,idlv fixed or
otherwise restricted from deflecting, then at -rest pressure parameters should be used for desigon,
Lateral pressure arising front surcharge loads. sloped backfi I I loads and earthquake loads should be
added to the above values to determine the total lateral earth pressures. In addition, transient loads
imposed oil the walls by construction equipment during backfilling should be taken into
consideration during design and construction, Excessively heavy grading equipment (that could
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TE.WReportAV 1-3398
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impose temporary excessive pressures or long-term excessive residual pressures against the
constructed walls) should not be allowed within about 5 feet horizontally of the walls. Increased
earth pressures can also develop from restricted soil drainage and compaction of the adjacent
backfill. Fxpansive materials, either natural or backfill, should not be within 3 feet of belmN g-rade
walls.
TABLE 1)
ESTIMATED LATERAL EARTH PRESSURE PARAMETERS'
Cobesive Soil
(non -expansive)
Cohesionless Soil
(granular or sand)
-Approximate Total Density
130 pcf
120 pcf
Approximate Friction Angle
150 - 200
_30' - 35'
Active Pressure Coefficient, K,
0.5
0.3
At -Rest Pressure Coefficient. K.
0.7
0.5
Passive Pressure Coefficient, KP
2
3.3
Coefficient of Friction for Sliding
at base of Concrete Footing
0.3
I
0.6
Active Earth Pressure 1) E lent Fluid Pressures —No Factor of Safety
Drained
Undrained 2
65 pef
95 pef
_335 pef
80 pef
At -Rest Earth Pressures — Design Equivalent Fluid Pressures — No Factor of Safety
Drained 2
Undrained
90 pcf
110 pcf
60 pcf
90 pcf
-
Passive Earth Pressures 4 —Design Equivalent Fluid Pressures
Drained
Undrained'
130 pcf
70 pcf
200 pef
100 Pcf
1. ASSIAnies negligible �vall friction, a vertical �Nall, level b, ill, and zero Surcharge loads. Excludes
cohesion shear strength and sliding friction effects.
2. Combined factored buoyant backfill unit weight and h\ drostatic \vater head (62.4 pcf).
3
J� ENChicles hydrostatic loading (62.4 pcf).
4. Passive pressure to be ignored in the Lipper 2 feet of finished grades due to frost and desiccation
effects. Factor of safety 2.0 has been applied to Iiiiiii: the aniount of lateral deformation required to
I
mobilize the passive iesistance.
Temporary Excavation Support
All excavations should comply with the requirements of OSHA 29 CTR, Part 1926, Subpart P.
"Excavations and 'trenches" and other applicable codes. This document states that excavation
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safety is the responsibility of the contractor. Reference to this OSHA requirement should be
included in the job specifications.
Cut and Fill Slope Stability Considerations
We recommend that Cut and fill slopes be constructed to 3:1 (hori7ontal to vertical) or flatter.
Fhcsc slopes will provide adequate stability plus �N ill be sufficiently flat to facilitate inowing for
maintenance of a grass stand recommended for erosion control. A MininIUM relativcly level
horizontal distance ofat least 10 feet beyond an) proposed floUndations and 5 feet beyond the edge
of any pavements is recommended from the crests of any slopes.
Construction Groundwater Control
During construction activities, care should be taken to maintain positive drainage at the site. Based
on the boring information obtained at the site, it appears unlikely that the groundvater will rise
above the lowest construction grade during construction unless severe precipitation is prevalent at
the time Of Construction. It is expected that the water seepage can be controlled by permitting it to
drain into temporary construction SUMPS and be pumped outside the perimeter of the excavations.
In areas where water bearing granular soils are encountered within the excavations, we recommend
that the water levels be maintained 2 feet or more below the bottom of excavations to prevent
Upward seepage forces which could reduce subgrade support. Dewatering in the water bearing
granular soils inav be accomplished with sand points and/or wells,
Groundwater control should be maintained continUOUSIN until below g-rade construction is
completed and backfilled sufficientlyto withstand the t6rces which would be induced by the rise
in g-round\Aatci levels when the dewatering system is no longer in service. If&roundwater control
is lost during, construction, disturbance of the Lipper fc�% feet below gorade is fikely in some areas of
the site. When this occurs, it will be necessary to reestablish groundwater control and remove the
disturbed soils. TEAM Services should be consulted regarding the extent of remedial action
necessary.
Site Surface Drainage
Positive site drainage Should be maintained along the perimeter of the building. Final grades
should be established to direct runoff away from foundations. Down spouts, gutters, and roof
drains should discharge away from perimeters. Site grading should direct surtace water away from
excavations or completed foundations during construction and after site development is
completed.
Page 17 of 21
Subsurface Exploration TEAM Services
Six Story Building - Iowa City, Iowa
TEAMReporlNo. 1-3398
October 9, 2013
Pavement Subgrade Preparation
We expect the soils which will be encountered to support the new pavement sections will consist
of reworked existing fill soils in cut areas, and engineered compacted cohesive fill required to
achieve the desired final grades. Due to the variability of the existing fill encountered, the most
conservative approach in dealing with the unknowns within the existing fill would be to
completely over -excavate and replace the existing fill. If the owner is willing to assurne the risk
of possible movements in the future, the existing fill could be left in place beneath the pavement
sections. If left in place, we recommend that extensive observation and testing of the fill be
conducted to further evaluate the suitability of the existing fill. If unsuitable soils are encountered
during this process, we recommend that the unsuitable soils be over -excavated and replaced with
engineered compacted fill. It should be noted that due to the limited depth and extent of hand
probing, that not all deficient zones may be detected during this process. As a minimum, the
proposed parking site should be prooftolled.
In order to provide satisfactory pavement performance, it is important that the subgrade support be
relatively uniform with no abrupt changes in the subgrade support. Therefore, we recommend that
the prepared subgrade depth be at least I foot deep after fine grading or trimming and extend 2 feet
beyond the edge of the pavements.
In cut areas it is recommended that the pavement subgrade area be cut to design subgrade level and
that the exposed subgrade be scarified to a minimum depth of 12 inches, moisture conditioned (if
needed), and compacted. In fill areas, the subgrade should be prooftolled to delineate zones of soft
soils present near the surface which may require additional removal or compaction, prior to fill
placement. We recommend that reworked existing fills or upper two feet of newly placed
engineered compacted soils be placed within a moisture content range of -2 to +3 percent of the
material's optimum moisture content. Cohesive and granular soils should be compacted to
minimums of 95 and 98 percent of material's maximum dry density determined by Standard
Proctor (ASTM D-698), respectively. Suitable engineered compacted cohesive subgrade would
provide a design support capability equivalent to a CBR value of 3 or a modulus of subgrade
reaction value of 100 pounds per cubic inch,
It should be noted that subgrade preparation to I foot depths for some soil types may not be suitable
under repeated heavy construction vehicle loads and may require stabilization to greater depths.
The subgrade preparation should be completed shortly before paving operations commence and is
to be maintained in suitable condition until paved. Damages caused by construction traffic or
deterioration due to adverse weather are to be repaired prior to paving. Subgrade compaction,
moisture content and depth should be verified by a TEAM Services representative prior to
pavement operations.
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Subsurface Exploration
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TEAM Services
Surface drainage around the pavement sections is important to long-term pavement performance.
Curbs should be backfilled as soon as possible, once adequate pavement strength is achieved. The
backfill should be compacted and sloped to prevent water firorn ponding and infiltrating Linder the
pavement. Water alloved to pond adjacent to the Pavement Could saturate the SUb&rade and
contribute to premature pavement deterioration.
Pavement Thicknesses
Fither flexible (hot mix asphalt. IINIA) or rigid pavement (Portland cement concrete. PCC) types
could be constructed on a prepared cohesive SUbgrade. Ifthe existing fill is lcft in place beneath
the Surface parking areas, it may be beneficial to Utilize hot mix asphalt since it is easier to patch
and/or repair. The following Table E summarizes alternate pavement thicknesses for typical
lightly -loaded and hcavil�-Ioaded paved areas constructed directl� on the cohesive subgrade and
on a granular base placed on the prepared cohesive subgrade. A more specific pavement
evaluation can be provided if traffic volume and loading information is available.
The below pavement thicknesses are considered to be typical and would require periodic
maintenance. This maintenance would consist of sealing cracks and replacement of isolated
distressed areas. Thickei pavement sections would reduce maintenance and increase the pavement
service lific. Likewise, thinner sections Would be expected to have a shorter service life that still
may satisfy partiCUlar project needs but may require more maintenance. Other criteria which
influence pavement ser\ ice life include Surface drainage. subSUrface drainage, paving material
quality, andjoint design. Construction procedures involving placement. finishing. CUring,jointing
and weather protection can significantly impact pavement performance.
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TABLEE
TYPICAL PAVEMENT THICKNESSES
TEAM Services
Flexible: Full -Depth Hot Mix Asphalt 2
Rigid:
Full-Deptli
.11 pe A over T.ype B HMIA
Traffic Volume
Portland
Type A
Type B
Cement
I
HMA
Type
Class I
Total HMA
Concrete
A
Thickness
Base
Thickness
Thicknesses below are based on the pa ement directly on the prepared cohesive subgrade
Lightly -Loaded 3
5"
6"
1.5"
5"
6.5 "
Heavily -Loaded �
7"
81,
1.5"
7"
8.5"
Thicknesses below are based on the pavement
oil 6" of crushed rock s base placed on the
prepared
subgrade
Lightly-fo ded 3
---
4.5"
1,51'
3.5"
5"
1 leavily-Loaded 4
6�5"
1.5"
5.�"
T'
I ) PCC - Flexural strenggth of 550 psi (compressive strength of 4000 psi).
- Structural coefficient of 0.50/inch.
2) Type A HMA inix with a mininlL1111 of 60% crushed aggregate
- Structural coefficient of0.44/ inch.
TNpe B Class f f MA nlix with a ininurrurn of30% crushed a&repte
- StrUCtUral coefficient of 0.404rich.
3) Automobile and I to 2 trucks average dail� traffic.
4) Enhances, delivery areas, chlulpster areas or othet areas ofheavier truck traffic
(25 trucks or less per day).
5) Crushed rock StrUCtUFat coefficient of 0. 12,inch.
QUALIFICATION OF REPORT
Our evaluation of foundation support conditions has been based on Out' understanding of the site
and proJect information and the data obtained in Our exploration. The general subsurface
conditions utilized in Our foundation evaluation have been based on interpolation of subsurface
data between the borings. In evaluating the boring data, we have examined previous correlations
between soil properties and foundation hearing pressures observed in soil conditions sirnilar to
those at youi site. The discoverN ofany site or subsurface conditions during construction which
deviate firorn the data outlined in this exploration should be reported to us for our evaluation. The
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assessment of site environmental conditions or the presence of pollutants in the soil, rock, and
groundwater of the site was beyond the scope of this exploration.
Support of structures on existing fill is discussed in this report. Existing fills are potentially Much
more inconsistent than nutural soil deposits. Support ofstructures upon existing fills carries with it
a degree of risk that unsuitable materials may be bLiried within the fill and not be detected in the
inspection and testing program recommended herein. Unsuitable materials in the fill may
experience Settlement Lind cause distress to structures Supported on the fill. Elimination of this risk
requires removal ofthe fill or supporting structures on suitable foundations such that the fill would
not adversely affect the structures.
It is recommended that the gcotcchnical engineer be retained to rev iew the plans and specifications
so that comments can be provided regarding the interpretation and implementation of the
geotechnical recommendations in the design and specifications. ft is fiirther recommended that the
geotechnical engineer be retained for testing and observation during the foundation construction
phase to help determine that (lie design requirements are fulfilled.
This report has been prepared for the exclusive use of our client for specific application to the
project discussed and has been prepared in accordance with ggenerall� accepted geotechnical
engineering practices. No other warrants, is provided. In the event that any charn,es in the nature.
desigon, or location of the project as outlined in this report are planned. the conclusions and
recommendations contained in this report shall not be considered valid unless the changes are
reviewed and the conclusions of this report modified or verified in writing by the geotectinical
engineer.
Page 21 of 21
2'Compacted non -expansive
cohesive soil cover, sloped to drain
away from the building —
1:2 (Horizontal to Vertical)
Minimum Granular Limit Lind
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PLANNING AND ZONING COMMISSION
OCTOBER 17,— 7:00 PM — FORMAL
EMMA J. HARVAT HALL, CITY HALL
PRELIMINARY
MEMBERS PRESENT: Charlie Eastharn, Anne Freerks, Paula Swygard, Jodie Theobald,
John Thomas
MEMBERS ABSENT: Carolyn Dyer, Phoebe Martin
STAFF PRESENT: Bob Miklo, Sarah Holecek
OTHERS PRESENT: Pam Michaud, Kathy Lynch, Brian O'Hara
RECOMMENDATIONS TO CITY COUNCIL:
The Commission voted 5-0 to recommend approval of ANN13-00002/REZ13-00023,
annexation of approximately 44.85 acres and a rezoning from County Residential (R)
zone to Neighborhood Public (P-1) zone for approximately 15.78-acres and to Interim
Development Residential Single -Family (ID) zone for approximately 29.07-acres of
property located on the west side of Sycamore Street.
The Commission voted 5-0 to recommend approval of ANN13-00003/REZ13-00025, an
annexation of approximately 15.14 acres and a rezoning from County Residential (R)
zone to Neighborhood Public (P-1) zone located south of American Legion Road and
Barrington Road.
CALL TO ORDER:
The meeting was called to order at 7:00 PM.
PUBLIC DISCUSSION OF ANY ITEM NOT ON THE AGENDA:
Pam Michaud of 109 S. Johnson Street said she is speaking in anticipation of a new business
that will be directly adjacent to the Low Density Multi -Family (RM-12) zone in which her historic
house is located. She said the location of the eatery will be on 525 E. Washington, and it's a
franchise called DP Dough. She said the restaurant will be open until 3:00 or 4:00 a.m. mainly
for carry -out seems incompatible in such close proxim4y to the residential zone and a zone with
stringent historic standards stringent standards imposed t maintain the integrity of the residential
buildings. She said she thinks it's very odd to have such and business just around the corner
and that it hours are, as far as she knows, open longest of any in the county.
Michaud said that although the City and Planning and Zoning staff have told her that they can't
limit how people run their businesses, she said that's not true. She said there is now a 2:00 a.m,
maximum for bars, a minimum distance of new bar permits, and other businesses whose hours
are regulated. She said so now in a Blue Zone there will be a new category of food —"drunk
food" as per reviews on the internet (Yelp!) from other college towns. She said she thinks this
business will have an impact on residents, including the many new renters in the area, including
those in the apartments above the business, who will be bothered bythe noise of people
Planning and Zoning Commission
October 17, 2013 - Formal
Page 2 of 8
returning from the bars in the wee hours of the morning as well as the lifter associated with such
food services.
Freerks asked if Michaud had talked to anyone on City staff. Michaud said she talked to Jann
Ream, who said they can't regulate business hours. Holecek said she would like to take
Michaud's remarks into consideration and get back to her.
Miklo said the only way they could regulate hours under the current zoning code is if it's a
special exception, and the Board of Adjustment sometimes imposes hours of operation on
those.
Michaud said she wanted to give them a "heads up" about Riverfront Crossings, too, because
there will be the same dense housing there and there will be a requirement for a commercial
space underneath the multifamily housing, and this in the kind of pressure there will be to fill up
those spaces.
Holecek noted that while there are businesses in other part of town that stay open later, she
acknowledged the concern about this location and said she would look into the matter to see if
they could make a recommendation. Freerks encouraged Michaud to follow up with Holecek.
Annexation /Zoning Items
ANNI 3-00002/REZ1 3-00023
Discussion of an application submitted by Iowa City Community School District for an
annexation of 44.85-acres and rezoning from County Residential (R) zone to
Neighborhood Public (P-1) zone for approximately 15.78-acres and to Interim
Development (ID) zone for approximately 29.07-acres of property located on Sycamore
Street south of the current city limits.
Miklo showed images and location maps of the subject property. He said the Interim
Development (I D-RS) zone is basically a holding zone that allows agricultural uses until such
time as that City infrastructure and a zoning plan are put in place. He said the southern fifteen
acres is proposed to be rezoned Neighborhood Public (P-1) and would be owned by the Iowa
City Community School Distinct, with the intention to build an elementary school there,
Freerks asked if the school district only plans on purchasing the southern section, Miklo said
that is correct. He said it's necessary to annex the northern section of land in order to make it
contiguous with the City boundaries.
Miklo showed the Comprehensive Plan for the area and said the proposed site was identified in
1997 as a potential school site or site for a large institution such as a church. He said the
thought is that in the long term McCollister Boulevard will travel across the southern part of Iowa
City and hook in with Scott Boulevard,
Miklo said when considering an annexation the first thing to contemplate is whether it falls within
the City's long-range adopted plan for eventual inclusion in the city. He said the long-range plan
calls for annexing to about one -mile to the south of the subject property.
Miklo said the second thing to ask is if the proposed annexation will fill an identified community
need and not impose an undue burden on the City. He said public schools in this part of the city
have capacity issues, and based on growth in this area the school district feels there's a current
Planning and Zoning Commission
October 17, 2013 - Formal
Page 3 of 8
and future need for more capacity in this neighborhood. Mildo said there will be some expense
to the City upgrading Sycamore Street. He said that is currently in the Comprehensive Plan but
in an unfunded year, so staff will recommend to Council when they prepare the Capital
Improvements Plan this spring to include the construction of Sycamore Street in the Plan in
order to provide appropriate access to the school as well as to future development in the area.
Miklo said the third thing to ask about annexations if it is in the best interest of the City to control
the area. He said staff feels that a large institution such as a school should be in the city where
it can be served by City services and have police and fire protection.
Miklo said there is sanitary sewer and water to serve the school, so with the exception of the
street infrastructure, this has the appropriate infrastructure to allow for rezoning. He said there
are some hydric soils on this property which may indicate the presence of wetlands on the
property so that will need to be considered when the designs for the school are made,
Eastham asked if there was any consideration giving to siting the school north of where the
McCollister/Sycamore Street intersection is, given that McCollister is an arterial and crossing to
the school could be problematic, Mildo said the school district did look at a site farther to the
north but they thought it would be too close to the Grant Wood School as they prefer to have a
certain distance between new and existing schools. He said there are schools all over the city
where the service area is on the other side of arterial streets, and those have been managed
well with crossing guards or traffic controls.
Eastham asked if the ID-RS zone would preclude the Commission's ability to zone for a higher
density. Miklo said it would not do so, The Comprehensive Plan shows potential for
Neighborhood Commercial, multi -family, a church or other institutional uses in this area, but until
an alignment and a plan is submitted, staff felt the ID-RS was the most appropriate designation
and the lowest density,
Freerks said she wants to be sure they talk about pedestrians and sidewalks and bikeways to
make sure the school is as easily accessible as possible. Mildo said they anticipate that a
sidewalk will be built at least on one side of Sycamore Street with the construction of the school.
He said the trail plans include a trail along the sanitary sewer easement through the area. He
said the actual school access is more likely to be a new east -west street, not Sycamore Street.
Swygard asked who would be responsible for that street. Mildo said it would be the school
district or the developer.
Thomas asked what happens to the land to the south. Miklo said there's potential there for
having town houses when it's annexed.
Eastham asked if the improvement of Sycamore Street would allow extension of a city bus route
to the school. Miklo said potentially it would, but there are other factors that need to be
considered for that to happen.
Freerks opened public discussion.
Kathy Lynch of Mikada Subdivision asked if they will be annexed into the city. Miklo said this
annexation does not include the Mikada Subdivision although the City's long range plan shows
that if there is growth in the area, it would be annexed.
Freerks closed public discussion.
Planning and Zoning Cmnmission
October 17, 2013 - Formal
Page 4 of 8
Thomas moved to recommend approval of ANN13-00002/REZ13-00023, annexation of
approximately 44.85 acres and a rezoning from County Residential (R) zone to
Neighborhood Public (P-1) zone for approximately 1S.Macres and to Interim
Development Single -Family Residential (ID-RS) zone for approximately 29.07-acres of
property located on the west side of Sycamore Street.
Theobald seconded.
Thomas said that identifying a school site is one of the critical foundations in building a sense of
community, and that's reflected in the Comprehensive and District Plans. He asked how the
selection of this site relates to the goals as stated in the Comprehensive Plan and the school
district's Diversity Plan to promote economic as well as other kinds of diversity.
Eastham said this is a thoughtful place to site a new school building. He said what he has
noticed, though, that as Thomas said, the Comprehensive Plan and the school district itself
have indicated that economic diversity within an elementary school attendance area is a goal,
He said from looking at a map that the school district published in 2010 and comparing the
number of students in different neighborhoods that are eligible for the Free Lunch Program,
which the school district uses to identify students of lower income, the areas that have been
developed more recently at higher densities with townhouses, duplexes and apartments
contained almost no Free Lunch eligible children in 2010. He said while he is supportive of
having higher density development as they continue zoning, that is in and of itself not going to
produce a distribution of lower and moderate income families. He said he thinks this a good
discussion to have and wishes that a school district representative had been in attendance, He
said as a Commission member he feels he has some responsibility to say to the school district
that the Commission is not going to be able to zone this site within a mile or so of what its
attendance area is going to be, and they are not going to be able to put homes that are going to
be affordable.
Freerks said she doesn't think that's something they can state right now
Eastham said they certainly can, and he would definitely support higher density residential
development within the attendance area of this school. He said that based on information that's
available to them as members of the public, it's unlikely that that step is going to produce much
in terms of mixed income of children attending the school in the future.
Holecek said they need to be careful about what kind of land uses will go in there. She said
Eastham can point out the correlation of the report he's read, but that shouldn't necessarily
create what his future decision -making will be. Eastham said he has already stated that his
intention is to support higher density development in this area.
Swygard said she wonders what other projects may be pushed back in advocating for the
financing in the City's Capital Improvement for this road improvement to be accelerated.
Freerks said that is a discussion to have at some point. She said this application is in
compliance with the Comprehensive Plan, and she will be voting in favor of it. She said it is
disappointing that no one from the school district was in attendance at this meeting.
Theobald said she wants to publically support that statement. She said she thinks the City and
the school district working together needs to be encouraged, and that would help with some of
the things that Eastham has mentioned.
Thomas said there aren't that many variables one has to work with to achieve the City's policies
Planning and Zoning Commission
October 17, 2013 - Formal
Page 5 of 8
and the District's policies, and it's up to both -entities to meet those policies.
Eastham said that planning for new elementary schools is something that is done infrequently,
but it has immense impact on what happens in the community. He said you would think that this
would be done over two or three meetings of the Commission
Miklo said staff of the school district did meet with City staff several times looking at different
sites and considering their concerns as well as the City's. He said he thinks this plan does
provide adequate infrastructure and fits into the long-range plans of the City.
A vote was taken and the motion carried 5-0.
ANN13-00003/REZ13-00025
Discussion of an application submitted by Iowa City Community School District for an
annexation and rezoning from County Agriculture (A) zone to Neighborhood Public (P-1)
zone for approximately 15.14-acres of property located on Barrington Road and
American Legion Road.
Milklo showed maps of the area. An aerial view of the property shows it as being used for
agricultural purposes and surrounded by similar land. Miklo said this would only include school
district property and would be zoned P for Public, which would allow an elementary school site.
He said the Southeast District Plan shows a greenway along the Snyder Creek stream corridor
and notes that public institutions such as schools would be appropriate along this greenway.
Miklo showed pictures of the subject property and the area. He said this is within the City's long-
range growth area, He said it would fulfill a community need, as there has been a lot of growth
in that area. He said controlled development is in the City's best interest, and staff feels that a
large institution should be served by public utilities and services. He said American Legion Road
is already in the Capital Improvements Plan. He said there are also hydric soils on this site. He
said the actual access would be Barrington Road, which would be built along the east side of
the property.
Freerks asked how far to the east American Legion Road would need to be improved for this to
happen. Milklo said possibly up to Taft Avenue.
Freerks said as traffic will increase, they need to make sure there's a plan for crossing American
Legion Road with pedestrian and bike traffic and she would like to see the City work with the
school district to make sure that happens. Miklo said that the school district has raised the
possibility of some sort of pedestrian underpass on the street and access to the trail in Windsor
Ridge.
Eastham said he thinks it is imperative that there is sidewalk access along the south side of
American Legion Road and on Scott Boulevard so the, students from Modern Manor and Sunset
manufactured housing areas along Scott Boulevard can walk and bike to this school. Miklo said
that is a short term concern. He said there is a long-range plan for a collector street in the
housing park. Eastham said he also shares Freerk's concerns that American Legion Road is
going to be busy and there are going to be several crossing points on that road for students
walking or biking to the school from the north.
Thomas asked if there was any discussion about a signalized intersection anywhere along
American Legion Road. Miklo said there wasn't.
Planning and Zoning Commission
October 17, 2013 - Formal
Page 6 of 8
Freerks said she thinks what they are saying here is that whatever occurs they try to plan for all
of the areas that need to travel to the school by bike, vehicle, or on foot, and make sure that it's
done the best it can be done because they have the opportunity to do it properly here.
Eastham said it would be helpful to him if the school district could give even a vague idea of
what the two attendance areas for these schools are likely to be.
Freerks opened public discussion
Brian O'Hara, who owns the property west of the proposed annexation, said when Windsor
Ridge was rezoned he contested it because of the Fringe Area Agreement. He said one of the
contingencies was that they didn't want to use the sewage lift pump or annex any prime farm
ground. He wanted to know if a sewage lift pump installed twenty years ago will be adequate for
500 more people. He said the storm water from the proposed annexation site goes to the
southeast and not to Snyder Creek so he's concerned about that. He said easements should be
in place for storm water retention and the sewer line should be installed before they make these
judgments. He said as they have annexed into Iowa City there have been no sidewalks from
Scott Boulevard on either side of American Legion Road.
Miklo said the City Engineer determined that the capacity of the sewage lift station is adequate
to serve what's anticipated for the school. He said the long-term plan is that will be a trunk line
along Snyder Creek when there is interest in development of the area. He said the sidewalk
issue is one they will look into incorporating into American Legion Road as it's built in the
Capital Improvements Plan. Miklo said that as long as O'Hara owns the property, he controls
how it is used. He said the storm water management will have to be addressed by the school
district when specific plans for the school are developed, He explained that the details of the
storm water management would probably come with the site plan, which the City Engineers
would review.
Freerks closed public discussion
Theobald moved to recommend approval of ANN13-00003/REZ13-00026, an annexation of
approximately 15.14 acres and a rezoning from County Residential (R) zone to
Neighborhood Public (P-1) zone located south of American Legion Road and Barrington
Road.
Eastham seconded.
Eastham said he had already voiced his main concerns about the sidewalk and trail access from
homes located along the east side of Scott Boulevard. He said he thinks this is a rational
location for another elementary school, He reiterated that he feels it would help a lot in the
Commission's planning decisions if they had a better idea of what the attendance areas are
likely to be here.
Freerks said that attendance areas will change, so more than just ensuring that the kids who are
slated for this area now can get there, it's that the community can utilize the area and all
pedestrians, bicycles and vehicular traffic can flow and travel to this spot. Eastham said Freerks
makes some good points.
Thomas said the comments he made on the previous item would apply here also. He said the
issues of walkability and bikeability are in all the City policies, and they must follow through on
them.
A vote was taken and the motion carried 6-0.
Planning and Zoning Commission
October 17, 2013 - Formal
Page 7 of 8
Consideration of Meeting Minutes: October 3, 2013
Eastham moved to approve the minutes.
Swygard seconded.
A vote was taken and the motion carried 5-0.
OTHER
ADJOURNMENT:
Eastharn moved to adjourn.
Swygard seconded.
The meeting was adjourned on a 5-0 vote.
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