The Fields Park: Brownfields, Compaction & Drainage – a Missed Opportunity

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The Park enterance, framed by the four bio-swales (I can’t bring myself to call them ‘water gardens’ as they look very ‘un-garden like’) that take runoff from the adjacent hard surface as well as from the drain system installed across the lawn. They are planted with Betula nigra cultivars along with Cornus stolonifera ‘Isanti’, C. s. ‘Kelseyii and an Iris. As you walk through the Park you will move over eight different hard surface treatments!

The Fields (Click here to see the final design plan), completed in spring of 2013, is Portland’s newest Park in the north end of the Pearl District.   While I was still with Parks I did the horticultural review during the design process and was an on site inspector, periodically, during construction.  New Parks like this one require a huge time commitment by Parks.  Selection of designers, outreach to all of the stakeholders and many other meetings involving more technical aspects of such a project all in an effort to deliver to residents a Park that is beautiful, serves the needs of residents and is affordable in terms of long term maintenance.  Before  the project is offered to the design community functional goals are set for the Park and a general design theme is chosen.  Various firms offer proposals.  Concepts are bandied about.  Eventually, one is chosen.  In this case, the Office of Cheryl Barton, a San Francisco firm, was awarded the design contract (To see what they have to say about it).

This Park is the third in a short ‘string’ of Pearl Parks, all of which would be tied together thematically by water features, their highly urban setting and an Ipe boardwalk.  It was part of the Portland River District Park System Urban Design Framework Study (January 2001). (A fourth Park, across Naito Pkwy, Riverfront Park, remains to be done.) Two Parks lay to the south of here, the nearest, Tanner Springs (finished in 2005), is a smaller passive use Park offering a respite and lunch place to observe the unfolding of a unique experiment intended to create a ‘functioning’ and contained natural landscape within a single city block.  Three blocks further south is Jamison Square (finished in 2002), a year round gathering spot for locals, with a low broad fountain and plaza that draws children from around the region to play in summer.

The Fields Park was to be the one that offered opportunities for informal activities with the capacity to support small events.  Unlike the other two it offers a large sunny lawn space.  It is also the only one to feature a playground, a rare amenity downtown.  Another goal was to provide the City’s first purpose built off leash dog area, separate from the main body of the Park to minimize conflicts with other users.

The Park was designed and built for a neighborhood with a quickly growing residential population housed in multi-story and tower structures that are still being added.  There were  a variety of reasons why this property sat vacant for a number of years while area developers and realtors were marketing their own properties with the Park as a selling feature, even before ground was broken.  Part of the delay in its construction can be attributed to this sites history as an industrial brownfield, it’s contamination a result of its historical use by railroad  and industry.  While this did not limit Portland Park’s ability, in any meaningful way, in terms of intended use, it did have a huge impact on ‘how’ the site could be built on and the protections that were required by Oregon State DEQ to prevent the movement of contaminants offsite through groundwater movement.  This single condition greatly impacted and complicated drainage issues and less directly, soil depth, both of which are vital to the success of any landscape.

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Imagine a ramp rising here around the north end and the ‘bridge’ flying across to the old mill site.  The project designers did, but it was not built.

The railroad tracks cut diagonally across its east and north. One of the biggest design features of the original concept, that was not built, was the ramp arcing around the north end that was to be the ‘launch pad’ for a foot/bicycle bridge that was to connect the Park with the Centennial Mill site along the Willamette and the future Riverfront Park, a bridge over topping the railroad tracks and Naito Pkwy, anchored to the Mill itself.  This fell through because of a variety of political, design and funding issues that are still not resolved.  The Mill site itself remains a bit of a moving target as far as its ultimate fate goes and is currently undergoing some demolition work that is removing the more ‘hazardous’ structures (Watching part of the removal process greatly saddened me as the massive timber framed structure was taken down shattering much of it, without attempt to salvage the old growth lumber.)

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This planting, part of the ‘dry stream bed’ on the plan, is surrrounded by hardsurface and base rock also creating a ‘bowl’ that will tend to contain water. It is planted with a drought tolerant grass that actually does not want summer water along with Iris ensata that demands heavy moisture at least through its June flowering period. Problem???  The pictures that follow appear roughly in order from the Park entrance moving around in a clockwise direction.

Many of my peers, still working for Parks, consider design review, on projects like this, vital to the work that they will inherit once any Park is completed and it becomes their responsibility to care for them. It was always one of our biggest frustrations.  We would be arguing for design changes for horticultural/technical reasons and project managers would under value our concerns sometimes for aesthetic commitments made to other stakeholders, other times because the contracted Landscape Architects refused to consider our input and others???  We weren’t part of those discussions.  From our perspective technical growing condition issues should take precedence over aesthetic design concerns as design options are nearly unlimited while horticulture concerns, like soil depth and drainage and even available labor, are more or less ‘fixed’ and must be addressed at some point or cost ‘us’ dearly later.

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This is a typical problem in a Park landscape. Hardsurfaces require stable base material, generally gravel, here it is 3/4 minus with larger rock beneath to support the occassional/routine use by Park’s vehicles. This base extends out from the hard surface on a relatively wide angle. The soil below it is compacted before the gravel/rock is installed. The surface to the right is an experimental porous concrete mix to minimize runoff. This requires the base rock as well to help contain the water that percs through. It may require even more base support as this porous mix has less structrual strength than ‘normal’ concrete. These two Gingko trees are planted in a space that is roughly 24″ wide but is effectively much narrower because of the base compaction and rock. These trees have two strikes against them.

This site was originally part of a much larger system of wetlands and shallow lakes that were filled for industrial development and the railroad (One story mentions how soil was sluiced down from the hills to do this.)  Tanner Creek was one of several streams that fed in.  The original grade is some 20’ below the current surface grade.  Its previous use resulted in the contamination of the soils here with a variety of pollutants.  As I mentioned earlier this is a brownfield site.  DEQ required that it be ‘hard capped’, that it allow no percolation of water down through the soil into the contaminated base soil which could potentially contaminate ground water and move it into the River.  This required that the entire site effectively send excess rain and irrigation off site.  Water can move into the soil where it may be taken up by roots and utilized by plants, but none may continue deeper.  In our winter rain season, when we regionally receive most of out precipitation, deciduous plants are dormant and use no water.  The water use of evergreens is greatly reduced due to air and soil temperatures that slow the plant’s growth processes.  This effectively requires that most of our annual rainfall be moved off site.

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There were three Fothergilla gardenii planted here. Now there are two and these are barely hanging on. They are suffering from base compaction, reflected heat and, ironically, wet soil (or at least they were over their first year, while the irrigation system was being tweaked.) Remember these are eastern woodlanders that prefer even moisture, well drained soil and less intense sun. The Isanti Redtwig Dogwoods running down to the left are much more tolerant/proven plants here in the West on a variety of sites though this particular location receives a lot of reflected sun and heat. This is adjacent to the SW entrance to the dog off-leash area.

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At the north end of The Fields where 11th ends at Quimby. This is a very simple planting of Amelanchier alnifolia with Geranium x cantabrigiense as a groundcover. This is normally a very dense groundcover, a good weed supressor, but on this site its having trouble filling in. One species groundcovers over large areas are often problematic in that there is nothing else to fill in if they have trouble. The Redtwig Dogwood against the fence in the background is the cultivar ‘Isanti’ and should stay in the range of 6′ tall so that it will require less routine cutting back than the species.

Water moves down through the soil with the pull of gravity.  It is slowed by the adhesive forces that tends to bind water to soil particles and the cohesive forces that hold water to water.  Fine textured soils, with their large surface areas and smaller open pore space between particle, slows the movement of water down through the soil as does the compaction caused over time by pedestrian use.  Soil is even more prone to compaction while it is wet and foot traffic is a serious source of compaction.  Once the water percolates down through the topsoil, there is only one and a half to two feet of topsoil here on top of the hard capped base, it stops.  It must now move sideways through the soil across a minimally sloping site.  Gravity’s force is greatly limited in aiding this sideways flow especially since the same soil that slowed its downward movement is now working against its more sideways flow.  It is effectively being slowed by a massive, somewhat porous dam.  This topsoil will then tend to to be more saturated than what most plants require.  Poor soil aeration will result in poor rooting and even rotting of those roots sent down more deeply during the summer growing season, assuming irrigation is not at a level that would create saturated conditions then too.  The crew has worked hard to tune this system so that that doesn’t happen.

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This northwest facing bank planting includes Cornus stolonifera ‘Isanti’ at the top, Perovskia atriplicifolia is the lighter grey middle band, with Cornus s. ‘Kelseyii’ below it followed by Helictotrichon sempervirens. These have differing water preferences. The bed is all on one irrigation station so it will be watered equally. The Blue Oat Grass at the bottom of the bank will be the wettest due to surface runoff while it ‘needs’ the least amount of water, in fact it is subject to rot with routine irrigation.

In a sense you could look at this entire site as a giant planter with a contained and limited soil volume.  A large pot will have drain holes to quickly waste excess water.  A large planter, especially one with a functionally sealed bottom, depends on soil depth to assure that plant crowns and roots have adequate soil aeration throughout the year.  Eco-roof gardens have a similar problem but with very limited soil depth.  Eco-roof systems recognize their water limitations and have some kind of interlocking grid that can support drainage flow across the bottom surface, below and separate from the ‘soil’, to drains or where it can be captured for reuse.  These grid systems work in tandem with topsoils that encourage percolation but won’t silt up the grid and slow or clog drainage.  I don’t know if anyone has every built such a system over a brownfield site but it does suggest an alternative, increase the soil depth and/or provide engineered soils and a drain system beneath.  On the Director Square site, engineered less dense, soils were brought in and placed on top of the concrete roof of the underground parking structure for weight considerations.  There the water percolates through and is able to sheet off on the concrete less inhibited because of the engineered soil which was a mineral material super heated and popped to expand its surface area and creating larger/coarser/less dense particles somewhat similar but denser than Pearlite.  All of these would have greatly increased the project’s cost at The Fields.  So, short of these alternatives, plant selections could have been made that were more in line with the soil conditions on site, conditions that varied, largely due to grade, in different areas.

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This is the controversial ‘off leash dog area’ specifically built for their exclusive use. This was contentious. Dog owners wanted a much larger area. This surface was designed to hold up to their year round use, no mud, ever. To do this it has its own drain system which also isolates the movement of dog waste and associated bacteria so that it doesn’t flow into they City’s sewer system, as per BES requirement. Concentrate anything into a small area and it becomes ‘waste’. In the foreground are Katsura Trees with a simple groundcover mass planting. Will it resist weed invasion? It is not now.

Designers seemed to concede this point on the large central turf area and a surface drainage system was installed to carry much of this off.  It should be noted that because most turf roots only in the top 6” of soil a saturated profile deeper would not harm it.  The turf area does remain very wet through out the rain season.

I tried to make the architects aware of this huge limitation during design.  My success was limited.

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A planting of Katsura Tree repeats around the north end of the lawn before yielding to White Redbud on the far, west, side. These appear to be well sited in that there are no hard reflective surfaces immediately to their south. This is, however, a relatively exposed site in terms of sun exposure. The soil could be a problem as these typically occur in Japanese woodlands with well drained, humus rich soils and the ‘protection’ of surrounding trees. If soils remain saturated through winter rooting will be compromised.

Plant Palette, Conflicts and an Alternate Path

It used to be commonly understood that tree roots went deep.  It has been a long education process to get as many people as we have now to understand that most tree roots are in the top one and half feet of soil, yes their are notable exceptions particularly among Oaks and some drought tolerant woody plants.  One might assume then that the topsoil here would be good for anchorage.  That is not the case.  The topsoil remains wet throughout the winter and is wetter as you go down.  It does not drain like my relatively heavy fine Latourelle Loam at home.  On similar sites I have plunged a shovel down into the top foot and hit standing water.  As I said the soil is very slow to drain due to the hard cap.  The rooting depth is therefore effectively reduced.  This will effect the long term health and stability of the trees on this site.

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This shot is taken from the ‘Urbanology Trail’ an asphalt path following a contour around the east and north side. This shows a 180 degree view which includes all of the new housing construction from the Encore on the left around to the west including the new Cosmopolitan On the Park luxury tower to the south. This shot looks across the intermediate bank uphill from the Urbanology Trail that could easily be replanted to a xeric planting scheme.

When we were in this design process, horticulturists Park system wide, were being directed to look for what we could to achieve savings in landscape maintenance due to projected cuts in labor.  One of the strategies is to plant xeric landscapes.  While this for obvious reasons could not be implemented quickly, over time such an approach could make a real difference.  The savings would come from lower water use, less maintenance in keeping irrigation systems operational and in having less weed removal/control work because we would not be watering all of the warm season weeds.  My suggestions of a plant palette that would enable this went no where on this project.

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The slope above the railroad tracks. This is not a lawn mix. A native mix including native  perennials and xeric evergreens was suggested but did not get planted. This bank is being dominated by Dutch White Clover, an aggressive non-native invasive and a variety of weeds including Canada Thistle. It gets cut down periodically with a string trimmer for ‘neatness’. The original RxR right-of-way had the typical array of nasty weeds selected by the Railroads use of herbicides. Several small trees have died on this exposed tough site, where I had also recommended a palette including West Coast Oaks and Madrone which are proving themselves on similar sites around the City.

We were given a design that did utilize a couple xeric plants but they were generally sharing beds with plants that required summer irrigation here to perform with vigor.  For example were several big sweeps of Ceanothus g. h. ‘Yankee Point’.  Most of these have failed.  I also argued that if we were to plant a low Ceanothus here there were better choices than this one, a very popular plant in California landscapes, but little used here.  I made several suggestions.  These suggestions required changing out entire beds due to their conflicting requirements.  There were other such conflicts one utilizing Festuca idahoense in an irrigated area and another planting Blue Oat Grass, Helictotrichon sempervirens next to Iris ensata.  That planting still exists with both doing poorly and slowly dying out.

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This shows the typical banding form of the plantings used on this site. The center strip is Ceanothus ‘Yankee Point’ more than half of which has died out here. It has done even less well elsewhere. The soil is heavy here and the bank receives regular summer irrigation which the other plants here benefit from. There are two smaller Vine Maple in the vacated middle distance. The grass is Calmagrostis ‘Karl Foerster’ which is rapidly running out of space where the Ceanothus remains, though the C. ‘Karl Foerster’ actually helps by blocking the uphill irrigation from reaching it.  This Ceanothus is typically a very vigorous form and was planted too tightly had they all survived.

The Park forms a long arc along its north and east side where the built up grade drops quickly down to the Burlington Northern railroad tracks.  There is an intermediate tier that’s paved, bounded for much of its length by cordons of Cornus s. ‘Kelseyi’ which actually, I admit, in winter looks nice.  This area with its more steeply sloping beds, and consequent better surface drainage, seemed like the perfect situation for a large xeric West Coast landscape featuring some of our many beautiful west coast natives including some of the smaller Oaks and yes Ceanothus along with Arctostaphylos and many others, of which we have many beautiful ones to choose, underplanted in a meadow of mixed native grasses, including Festuca rubra commutatta and perennials.  This idea was never discussed though I pressed for it repeatedly.  Some natives were planted though they weren’t necessarily very good choices.  Many of the Vine Maples planted here have died out.  These typically occur in woodland conditions which this is not.  A White form of Eastern Redbud was planted and is hanging in there.  Some native Nutallii Dogwoods didn’t make it.  Note that this and all other sites are receiving regular irrigation as are the weeds that have moved in.  Again, the Ceanothus that were planted have mostly died.  For me, though I like the design, in terms of layout and flow, I view the landscapes here as a lost opportunity with a very limited palette that offers limited seasonal interest.  Perhaps, over time, staff can move them in a more xeric and sustainable direction.

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The bank to the north. This area is steep which complicates the regular maintenance work now done here. The fences at top and bottom compound it by limiting access. Here are the remaining Cercis canadensis ‘Alba’. Other woodland edge small trees have failed on this hot exposed site.

I can envision this whole back bank planted in west coast natives with specimen such as Fremontodendron, Carpenteria, Garrya, select Ribes in addition to the Manzanita and Ceanothus I’ve already mentioned.  The same theme could continue in many of the other beds especially those sweeping along the north sloping down to the fenced ‘dog area’.  Some of it could be used to feature/display some of the particularly well adapted Mediterraneans like the many Cistus and Halimium.  This group of plants have been successful on many other sites across the Portland area…just keep the summer water off.

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The portion of this bed next to the turf and adjacent to the ‘Encore’ was all planted in Fothergilla gardenii. Virtually all of it died. Some was replanted and died again. This area is poorly drained and also suffers foot traffic between the two hard surfaces as it has no evergreen winter presence to direct traffic.  Looking closely, you can see the remaining stubble of the surviving Hakonechloa macra, a warm season grass that ‘disappears’ in winter for five months so is even more subject to being stomped out. The Hamamelis, added later, is an attempt to address the traffic issue.  This planting has since, in 2016, been further modified by staff in an attempt to make it more successful.

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This picture shows two typical problems found in many designs, first, and perhaps most obvious, is the widely spaced bunch grass clumps with open mulched ground that will always be susceptible to weed invasion requiring much manual control and/or the use of herbicides, commonly both post and pre-emergence types. The other issue is single species ground cover masses, essentially monocultures, that are subject to invasion by certain weed species that vary with the ground cover. Successful ground covers have been increasingly demonstrated to be mixes of complementary species, ‘plant communities’,  that work in association with one another to fill available niches. Single species are more subject to failure as there ability to compete with weeds is narrow. They are also more likely to result in thin or bald spots. Highly successful single species ground covers are themselves border line invasive and can act as ‘thugs’ in the landscape crowding out desirable plants.  There is the additional issue of ‘interest’ as plantings like these can be monotonous.

There were other planting issues on this site that had to do with a particular plant’s use in mass that was/is problematic and others like the Fothergilla gardenii that had inadequate rooting space, poor drainage, too much reflected sun and probable conflicts with use given their more brittle structure.  Or, the Japanese Forest Grass, Hakonechloa macro Aureola, that completely melts, having no winter structure to warn pedestrians away from the bed and the damage that such traffic brings.  There will always be ‘quibbling’ in projects like this.  What is more frustrating are the larger site condition problems that go unaddressed and the always present issue of maintenance and the pressure to become more efficient with landscapes that could have been more effectively designed to reduce the work load.  Politics, internal and external, often drives decision making…at a cost.

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This is a narrow ‘trench’ planting hemmed in by the porous concrete path to the left and curb bounded by the playground on the right. The ‘trench’ itself contains a large number of water pipes supplying several of the 80 stations that irrigate the park as well as electrical conduit for the Park’s lighting. You can see three valve box lids in the photo. Over time it is highly likely that parts of this area will be dug up for repair reasons. People also tend to walk up to the fence and a high neighborhood dog population is ‘exercised’ along this path where they frequently urinate affecting soil pH. Most of these Fothergilla along the fence are stunted some have been broken. This and the next several pictures are from the south end of the Park around or near the Playground.

Those of you who have gotten this far shouldn’t think that I was an unhappy employee that bears a grudge against his former employer.  I simply have high expectations of Parks.    Any organization tends toward conservative decision making and operation.  They become more so as they increase in size.  They tend to offer little internal support for innovation and creativity, despite what they may insist.  These are viewed internally as ‘risky’ behaviors.  It is always better to go with the old tried and true…even if it has demonstrably failed in the past, because it is the safe, ‘proven’, course of action.  If one fails doing what one is told, what is conservative, while it may not be liked, the person will likely receive little ‘blowback’, because it is what most would have done.  If, however, you push the edge, try something new or from beyond what is expected, and it ‘fails’, or someone important doesn’t like what you’ve done, there will be no one there to back you.  I don’t know how much of a factor this was here at The Fields, but I do know that when a project costs several million dollars, nobody wants to look bad.  When decision makers don’t know or care to understand the underlying problems and issues, it is difficult to deliver a quality product, to do your best, most responsible work.

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Again, Hakonechloa has gone dormant. Its lack of presence during winter months into spring, gives the impression that nothing grows here. This grass is generally used as a specimen or edging for more substantial plantings, not a mass such as here.

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This is the bed bordering the Encore off of NW 10th and Overton. The bed has no winter presence and as such will be subject to stomping by users moving between the two areas. There is no evergreen presence, no woody plant structure, stone work, benches or even curbing to direct foot traffic away.  Many/most people will take a direct line to get to there ‘destination’.  Desire paths are created when users are not ‘blocked’ from otherwise open space.  This was pointed out during design. The building owners/developers wanted open access and the designers were resistant.

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This strip planting along the south side of the Playground was filled exclusively with Fothergilla gardenii.  It has had three growing seasons to settle in and grow.  While it is a compact grower with a tendency to produce basal shoots, it has suffered from poor soil conditions and reflected heat from the hard surface, or in some cases been stomped out. People walk up to the fence. Many of us have argued that high activity areas, such as playgrounds, should not have adjacent plantings especially any that may be brittle. The fence is intended to contain playing children. The sand in the play area is continuously being scattered in to this bed burying the crowns of the plants.  For some reason these Gingko trees were planted just a few inches from the fence (perhaps because irrigation lines and conduit runs down the middle?). What happens to the fence when/if they grow to mature size?

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These swales are at the low south end of the Park. The turf drainage system is piped directly into these. The water that is directed here cannot escape via percolation through the bottom. All of the swales have an impermeable pond liner beneath the soil, again to prevent percolation down to groundwater and movement of the contaminants.  Staff consider these to be the most successful, visually, of any of the Park’s plantings.

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A large 8″ inlet is in the center right of the photo. The bio-swales are planted with Juncus and Carex, both evergreen, and capable of winter growth/water use in addition to the Cornus. The excess is carried away from each of these by a large drain in the center.

Portland Parks could be a leader in terms of its plantings, educating the public in the process while providing beautiful landscapes.  Today, too often, our big capital projects produce innovative built landscapes, structures, then adorn them with uninspired plantings that serve primarily as space fillers, repeating broad single species swaths and bands.  Plantings, that in their simplicity, habit and requirements, often ignore growing conditions thus promising a need for a continual and demanding level of maintenance.  There are pockets of inspired plantings around the Park system, generally done by horticultural staff over time.  It is sad that collaboration between these two divisions is not the norm.  While no one has all of the answers, horticulture attempts to understand the relationships of plants with both their place and each other.  These relationships are real.  The cost of ignoring them is real as well.  Landscape design cannot just be a ‘graphic’ art put in service to meet human demands and needs.  Without the science of horticulture, our ability to observe and learn, many of our plantings will fail. Horticulturally speaking this is not a sustainable design.  It is not xeric.  It requires way too many resource and labor inputs to be considered so.  Sustainable landscapes are not so because people insist that they are.  They are a definable entity. Missed opportunities all!

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