Guest Viewpoint: Geoff Larsen

Thickened aggregate working pad.

My schedule this weekend is particularly full, so in lieu of an original blog post, the following is reprint of an article written by current Construction Specifications Institute - Willamette Valley Chapter president Geoff Larsen, PE, CSI that appeared in the August issue of The Documentor. Geoff is an Associate and Senior Civil Engineer with Mazzetti/BHEGroup’s Eugene office. His article provides an excellent summary about the critical issue of soil conditions, particularly here in the Willamette Valley where clayey, silty soils and the significant concerns that come with them predominate.

The topics of soil conditions and earthwork are far from central to an architect’s education, but my own experience has taught me they can have an outsized impact on a project if not properly anticipated during the design phases. For this reason, it’s important for architects to possess a basic understanding about the issues they present and how they may be addressed in Division 31 of the Project Manual.

Division 31 - Soil Conditions and Earthwork in the Willamette Valley

By Geoff Larsen, President WVC/CSI

At the midpoint of the dry summer construction season, I am reminded of the varied soil conditions that are exposed with excavation and earthwork for projects throughout the Willamette Valley. Although soil conditions are different for each project site, there are some common issues that crop up during earthwork construction for each project. I would like to take this opportunity to reflect on some of those common issues and share some notes and lessons learned related to the Division 31 Earthwork specifications.

 

Division 31 Earthwork Specifications and the Geotechnical Report:

Project earthwork specifications are found in Division 31 and may include multiple sections (i.e. Aggregates, Site Clearing, Grading, Excavation, Fill, Compaction) or may be consolidated into fewer sections (i.e. Earthwork or Earth Moving). The technical details of the earthwork specifications are a subject for another discussion. However, in a nutshell, the earthwork specifications should reflect the recommendations of the geotechnical report and should establish a framework for working with the existing onsite soils (excavation, protective measures, stabilization, etc.) and for placement of imported soils (base rock, drainage aggregate, backfill, etc.). Since the approach to earthwork can change as a result of weather conditions, concealed conditions, and construction methods, it is also beneficial for the Division 31 specifications (in coordination with Division 1) to set a framework for dealing with potential changes to contract time and contract amount.

Sensitive Soils and Protection from Damage:

Soils in the Willamette Valley are often clayey, silty soils that are easily disturbed when excessively moist and are often susceptible to damage from construction equipment. Within the footprint of new building or pavement areas, soils that are excessively soft or that have been damaged by construction equipment will need to be excavated and removed (referred to as “over-excavation”) to reach a firm bearing surface. This over-excavation is then backfilled with stable material (typically imported aggregate). Conducting earthwork during the dry season can help limit the risk of damaging the underlying soils (subgrade) but some soils may be slow to dry out, even during the dry season, which can be problematic for accelerated construction schedules. To address this issue, it is common to provide a thickened rock working pad or cement treatment (see below for further discussion) to protect or stabilize the underlying soils in areas where construction vehicles will operate. For large projects, the cost of protective or stabilization measures may be significant, and the Owner may choose to reduce protective measures to save cost, understanding that there is increased risk of additional cost and time to deal with over-excavation and repair if damage to the subgrade occurs. Regardless of the approach, it is important to establish a structure for subgrade protection within the Division 31 specifications and to communicate the alternatives with the stakeholders. The following are important questions to consider: 

• Is subgrade protection/stabilization (rock pads / cement treatment) defined/required by the specifications? 
• Who is responsible for the cost of repairing damaged subgrade soils when protective measures are not in place (contractor or owner)?
• How is the contract adjusted when unsuitable soil is encountered or when protective measures are followed but the subgrade still becomes damaged and requires repair? Are unit prices utilized?
• How is construction monitored to determine when unsuitable soils are encountered or when the subgrade is damaged and requires repair? When will geotechnical inspections occur?
• How is the extent of subgrade repair (over-excavation) monitored and measured?
• Are there different requirements for wet-weather construction?

Subgrade Stabilization – Cement Treatment:

Cement treatment of native soils involves mixing cement with the upper layer of soil (12” depth is common) and then compacting. Once cured, the cement-soil mixture provides a stabilized surface. Cement treatment can be a cost-effective solution for sites with particularly poor/unpredictable soils, sites with large paved or building areas, or sites where construction will occur during the wet season. Cement treatment can also provide a higher level of cost certainty than conventional aggregate base stabilization due to lower risk of over-excavation and damage from construction equipment. Excavation for footings or utility trenches through cement-treated subgrade can be more challenging, so construction sequencing should be considered carefully.

Unit Prices:

Unit prices can be an effective way to control costs if subsurface conditions are highly unknown or highly variable and the quantity of over-excavation is unknown. The cost of rock excavation is significantly higher than typical soils, so unit prices can also be a good strategy when rock excavation is anticipated. When evaluating unit price bids, it is important to consider the anticipated probable range of excavation quantities when comparing bids. For example, a bid with a low base bid and high over-excavation unit price may result in a higher overall price.

Measurement and Payment:

Measuring soil quantities for repairing unsuitable or damaged subgrade soils can be a point of contention if not properly defined in the contract documents. It is particularly important to be diligent about units of measurement if utilizing Unit Prices for contract adjustments. Typical units of measurement include in-place volume (bank cubic yards) or in-truck volume (loose cubic yards).  Although in-truck quantities seem like a simple way to measure quantities, in-place quantities provide a more definitive and verifiable basis of measurement. Soil changes volume (increases) when excavated, so there is always a difference between in-place and in-truck quantities. For large projects with potentially large areas of unsuitable soil removal (over-excavation), it may be necessary to verify in-place quantities using survey equipment.

Geotechnical Construction Administration Services:

As projects move toward the construction phase, it is important to have the appropriate geotechnical and testing services in place to monitor earthwork once construction is underway. The native soil directly below building foundations is a critically important interface and it benefits all parties to ensure proper subgrade inspection by the Geotechnical Engineer prior to pouring foundations. The contract documents should be clear about who is responsible for procuring the testing and inspection services.

Proactively thinking about these issues has helped me on past projects to set expectations, provide cost control, and has led to successful projects. If you are a Specifier, Architect, Contractor, or Engineer, I hope these notes can help you bypass predicaments related to earthwork and set your projects up for success.

Geoff Larsen, PE, CSI

Enjoy the rest of your summer (and the dry construction season)!

Light

Vancouver, August 18, 2019 (my photo)

As I write this, I’m in Vancouver, B.C. visiting my aging parents, who welcome the distraction my company brings from the cheerlessness of their daily routine. I likewise appreciate the opportunity to see them, especially now that each of my too infrequent visits is increasingly precious (my father is 91 and my mother is 90). I tend to be wistful and nostalgic each time I’m here, but I seem especially so during this stay.

It’s mid-August, but Vancouver is gray, cool, and misty. The watery, flat light is familiar and comforting to me. It is also unlike the light I’ve experienced most everywhere else. Even the light in Seattle, to which Vancouver is frequently compared, is different. Exactly what makes it different is hard to put a finger on. I suspect Vancouver’s forested North Shore mountains play a part. Maybe too just the few degrees of latitude that separate the two cities. Even when the persistent veil of clouds does dissolve, Vancouver’s sky is less radiant, and perhaps more cerulean in hue than its American counterpart. What I do know is a considerable share of Vancouver’s sense of place is attributable to the unique quality of its light.

Vancouver’s characteristic light contributed to the signature murk of the of X-Files television series, a mood-setting, melancholic dreariness the show would lose following its move to Los Angeles during the final years of the series’ long run. The X-Files was never the same.

Humans have exploited daylight and controlled its effects since they first began building. Notable architects assigned to light preeminence among other critical design considerations. For example, Le Corbusier described architecture as “the learned game, correct and magnificent, of forms assembled in the light.” And Louis Kahn memorably said of light that “Architecture appears for the first time when the sunlight hits a wall. The sunlight did not know how magnificent it was until it hit that wall.” Prominent among the works of both Corbu and Kahn are some of modern architecture’s most revered paeans to light (for example, the Chapel of Notre Dame du Haut at Ronchamp and the Kimbell Art Museum, respectively).

There’s no doubt any architect worthy of the title will acknowledge and develop an understanding about the quality of light specific to a place. Historically, the specific attributes of that light impacted how architects design as much as matters of program, topography, tradition, or technology. Stylistic variation developed over time, distinguishing regions from one another. It’s why the brilliant, harsh light of equatorial settings favored bold, elemental geometries (think of the pyramids), while the mostly grayer skies of northern climes prompted a greater interest in elaborate silhouettes and profiles (such as the spires and filigree of Gothic cathedrals).

Today of course, advanced glass technologies offer architects the freedom to design walls entirely of glass, irrespective of a given site’s light conditions, the building’s orientation, and views; however, simply because glass walls are possible doesn’t mean we should apply them so liberally. The beauty of individual windows—their shape, proportion, sill depth, and reveals—imparts much of the character and regional specificity buildings historically have possessed. Architects who seriously consider a setting’s peculiar luminosity are more likely to produce designs featuring carefully considered, tailored apertures.

I find it comforting to be reminded when I travel that here is not always like there. Places are different despite humankind’s inexorable and unwitting efforts to homogenize our world. Vancouver is unique because of its spectacular setting but also because its distinctive light has influenced its architectural heritage, from the mildew-y shabbiness of its ubiquitous, cheaply built housing to the transcendent, shimmering works of West Coast modern masters like Arthur Erickson. Great architecture glows from within but is invariably defined too by the natural light that envelops it.

Architectural Principles of Aldo Van Eyck

Hubertus House, Amsterdam – Aldo + Hannie Van Eyck, architects (photo from the Aldo+Hannie van Eyck Foundation website) 

My college professor Bill Kleinsasser greatly admired the Dutch architect Aldo Van Eyck (1918-1999), whose interest in how people use and experience architecture he found entirely resonant with his own. Van Eyck is best known in architectural circles for being a co-founder of Team 10, a loosely affiliated group of European architects who advocated a humane form of urban planning during the post-war era. Bill developed a thorough understanding of Van Eyck’s work and writings, and he shared what he learned about Van Eyck’s architectural principles with his students. In particular, Bill appreciated the Dutch architect’s clear demonstrations of those principles in his built work, of which the Hubertus House (photo above) was a particular favorite. 

Despite Bill’s veneration of Van Eyck, I didn’t fully understand his enthusiasm for Van Eyck’s work during my University of Oregon days. Today—nearly four decades on—I’ve come to share Bill’s appreciation for the principles Van Eyck promoted. 

I excerpted the following from the 9^th edition of Bill’s self-published textbook Synthesis: 

Architectural Principles of Aldo Van Eyck

For years, Aldo Van Eyck’s architectural philosophy has espoused goals and concerns that are essential. Always humane (“. . . architecture need do no more, nor should it ever do less, than to provide BUILT HOMECOMNG), he has demonstrated again and again what his principles mean in built form. His buildings are showcases of applied architectural theory. It is a significant theory because it is centered on the feelings and perceptions of the people who will use the spaces provided, on the immutable characteristics of people in general. More than most other architects, Aldo Van Eyck has developed an architecture that provides an informed, unsentimental, yet rich framework of opportunities for its users; therein is the significance of his work. 

Here are some of his general principles: 

• Make places that haven’t got what they needn’t have (but do have what they need)—in both cases this is a lot, all sorts of things. 
• Make buildings that fit where they are put. 
• Identify each building with that same building entered, and hence with those it shelters, and define space—each space built—simply as the appreciation of it, including what should never be excluded but paradoxically usually is: those entering it. 
• Make each building an autonomous counterform of perpetual homecoming (like the shell to the mollusk). 
• Retain an intrinsic ambiguity (scope for multiple meaning). 
• Achieve labyrinthian clarity (ally of significant ambiguity, it harbors bountiful qualities). 
• Make place and occasion instead of space and time; make a welcome of each door, a countenance of each window, each place a bunch of places, each house a tiny city. 
• Emphasize what doesn’t change, has never changed (at no time can an architect be a prisoner of change). 
• Learn how others did it (a conscientious architect is freer than the fool who does whatever he/she likes or whatever enters his/her head). 
• Make places that are useful, gentle, cheerful, GOOD. 
• Offer multiple meaning in equipoise.

Here are some specific principles too, to facilitate implementation of the general ones: 

• Establish and reinforce connections to (awareness of) adjacent and surrounding features; that is, help people know and remember where they are by providing references. Be sensitive and respectful about how the connections are made. 
• Create internal references too—inner horizons-by letting the building itself (and people in it) be part of the view. 
• Use stairways, corridors, and entries to reveal (and vary) the inner horizons (to clarify and vitalize). 
• Inflect (adjust or vary), where differentiation is possible and appropriate (to articulate, thus to separate, but also to join). 
• Reveal certain essentials about the arrangement straight away (from the outside) and use entries, corridors, stairways, lifts, and views to continuing this clarifying, orienting, reassuring revelation. 
• Locate elements wisely: consider the experience of those who will use the space, use great empathy and testing (rehearsing) to determine which arrangements are best, remember other good places, and trust feelings (but not just feelings). 
• When there is more than one condition to support—and this usually the case—provide for multiple possibilities (avoid choosing one over another, your choice will inevitably be wrong). 
• Make bunches of places and articulate them. 
• Make the fixed structure in such a way that it may be read in many ways. 
• Create transparency—open everything up to reveal the whole. Let light come in and space go through but include enclosure in the opening up. Develop inner horizons as points of reference and security. 
• Make a complex perimeter (at the top as well as on the sides). Articulate the implied in-between (tight-rope dance along the building line). Make balconies, bays, roof gardens. 
• Extend entries inward and begin to enter far outward; think of each departure as entry. 
• Vary spatial depth and perceptible distance (extend lateral and vertical openings and articulate the elements along the views). 
• Vary positions of stairs, entries, windows, paths to shift views (positions) of inner and outer references (to complexify and to clarify). 
• Articulate each entry, stairway, and corridor to outline the organization of the whole, thus clarifying it. 
• Support a light framework on a heavy base, then heavy up the light framework (for instance with color) and lighten the heavy base (for instance with mirrors to break up its mass). The original two (base and framework) thus become multiple and the whole more complex. 
• Use details via Rietveld (details that explain what they do and how they were made). 
• Use color and structure to define elements. Avoid vagueness which destroys both part and whole. 
• Establish readable, relatable information about the building for each distance at which it is perceived. At no distance should the building go blank or be untrue. 
• Vary the building and the reference frames so that each person using the building will be able to find fitting, familiar conditions.

Tykeson Hall

Tykeson Hall (all photos by me)

The opportunity to tour a building before it opens and hear firsthand accounts of its design from those directly involved in its realization is always a treat. Such was the case last Wednesday with Tykeson Hall, which will be the newest academic building on the University of Oregon campus when it opens its doors to students this fall.

I joined a large group comprised of members from the local sections or chapters of AIA, CSI, and ASHRAE for a sneak peek at the nearly complete facility. Our able hosts were Chris Andrejko, AIA of Rowell Brokaw Architects PC and Greg Langdon, PE of Systems West Engineers. Chris and Greg provided us with an introduction to the project by describing its general organization and design features before allowing us to explore the building on our own.

Chris Andrejko, AIA (left) and Greg Langdon, PE

Tykeson Hall will house numerous advising and student resources for the College of Arts and Sciences (CAS), previously scattered about the campus. Additionally, it will provide much-needed classroom and faculty office space within the heart of the university. The enclosed floor area totals 64,000 square feet across four floors plus a basement. The project cost $31 million to build.

Situated between Johnson Hall and Chapman Hall, the new building upholds the university’s comprehensive Campus Physical Framework Vision by establishing stronger connections between major pedestrian circulation routes and clarifying the structure of open spaces in its vicinity. Its compact form preserves the south-facing open space by Chapman Hall, forming an outdoor room (dubbed “The Oval”) for campus events. One day, Tykeson Hall and a future academic building at the intersection of E.13th Avenue and University Street will bookend and frame historic Johnson Hall.(1) 

Organizational diagram.

Second Floor Plan.

Rowell Brokaw Architects partnered with Office 52 Architecture of Portland to design the project. PLACE provided site design and landscape architecture services. Together, the team delivered a respectful piece of architecture that neither clamors for attention nor is entirely deferential. The building balances both traditional and modern expressions within an admirably clear and diagrammatic parti. Janus-like, Tykeson Hall unapologetically presents two faces toward its surroundings.

West elevation facing The Oval.

Its unique terracotta rainscreen distinguishes the “modern” face oriented west toward The Oval. While several of the university’s historic buildings feature ornamental terracotta details on their facades and entries, Rowell Brokaw and Office 52 use the material in a decidedly contemporary manner. Manufactured by Shildan and installed by Streimer Sheet Metal, the terracotta is applied in five distinct, custom glaze colors as a rain-screen cladding. The team detailed the open-joint system with 3/8 inch gaps between the terracotta panels, and carefully planned the material’s layout to avoid adjacencies between panels of the same color.

Though the terracotta is striking, I do wonder if its resolutely planar application represents a missed opportunity to exploit its plastic and decorative potential. At the height of its popularity as a building material during the late 19th and early 20th centuries, architects often embellished their designs with elaborately sculpted terracotta components (the work of Louis Sullivan stands out in this regard). While terracotta is seeing a resurgence of its use in recent years, today’s architects seem reticent to make full use of its inherent properties. If they did, we might see new work displaying the coherent levels of scale, geometric recursion, and fractal patterns of the types we intuitively respond to in historic and vernacular architectures.

Terracotta detail at the northwest corner of the building.

Tykeson Hall’s east, “traditional” brick side employs a subtly variegated blend of colors and a unique cross bond pattern to visually complement its historic neighbors. Despite the site’s prominence on 13th Avenue—the campus’s most significant central circulation corridor—the new building exhibits a sympathetic scale and a welcome absence of posturing.  

View from 13th Avenue looking toward the northeast corner.

The contrast between the two exterior expressions of Tykeson Hall also articulates the pattern of the functional program within the building. The eastern portion of Tykeson Hall primarily houses six flexible classrooms, while the west side accommodates a series of collaborative spaces and a ground-floor commons that opens in good weather toward The Oval. An inviting, open stair featuring an interactive art piece by Narduli STUDIO connects all five interior levels, as does a skylight-topped, central light well.(2) I appreciated how Rowell Brokaw and Office 52 assigned each floor a unique geographic theme to inform the color and finishes palette, evoking Oregon’s High Desert on one floor, its coast on another, and so on. The otherwise unassuming interior spaces will undoubtedly be pleasant and functional when in use.

Interior view.

Chris and Greg said Tykeson Hall should be 35% more efficient than the current Oregon Energy Code requires, and is on track to achieve LEED Gold certification. Daylighting, natural ventilation, radiant floors, chilled beams, and a high-performance building envelope will all help to lower the total energy consumption of the building.

Overall, Tykeson Hall bodes well for the University of Oregon in its efforts to preserve the unique character of the campus. Promoting and protecting a strong sense of place—as opposed to provocatively disrupting it—is the order of the day. The duty to protect the sense of place demands that architects entrusted to design new buildings do so with a full understanding and appreciation for the planning framework that underlies the campus fabric.

(1)     The future development of a proposed building will require moving Collier House to another location yet to be determined. 

(2)     Horizontally deployed fire-rated curtains enclose the floor openings at two levels, obviating the need for a mechanical smoke evacuation system within an atrium.