Wednesday, March 22, 2017

Lincoln Park


Lincoln Park is one of the better documented beaches on Puget Sound, although much of what was written is now 25 years old. And apparently, this is the first time I've included it in the blog. A good reminder that there are just too many beaches.

The glacial landscape of West Seattle juts out into Puget Sound on the north side of Fauntleroy Cove. As commonly occurs on promontories on Puget Sound, a very small depositional landform - a cuspate foreland - has formed at its tip (this is in contrast to Brace Point, to the south, which is a much larger cuspate foreland). You may have learned in Beaches 101 that headlands get eroded and bays get filled in until the whole coast is straight, which may be true if you're on a coast where large waves approach straight on. But here on Puget Sound, where waves approach at a strong angle to the coast, it seems that sometimes sediment is attracted to the points, not removed from them. Or at least that's sure what it looks like to me.


AERIAL VIEW


The photos show both the more heavily visited south beach and the somewhat less explored north beach. And the riprap that protects the point itself. Note that this landform was perfectly happy without riprap, despite its exposed position, for hundreds of years. The riprap probably reflects the need to protect the walkway, which was likely built over the original backshore. Colman Pool (saltwater) replaces whatever little lagoon probably once occupied the same place on this landscape.

The south beach is the main story here. During the 1930s, the WPA built the stone bulkhead (now largely buried) and the promenade. Over the next few decades, the beach eroded and dropped in elevation and by the 1970s the wall had been repaired many times. Old photos show the beach far below the top of the wall. When Seattle approached the Corps of Engineers for help, the Corps proposed beach nourishment. Resource agencies pushed back - the idea of burying the beach under fill was unthinkable (they preferred the idea of a riprap apron at the toe of the wall).

Fortunately, nourishment won out over riprap. The initial placement in 1988 was large - something like 80,000 cubic yards - but the few subsequent renourishments have been much smaller. And despite some wrinkles along the way, I think the overall project remains a big success story. I think it was critical in reshaping the opinions of the agencies about the potential value of nourishment. This was also because monitoring, required of the original project, led to some good early work on Puget Sound beach biota and their response to seawalls and nourishment.

Wolf Bauer, who had been advocating and building gravel beaches on Puget Sound for more than a decade before the work at Lincoln Park, was a bit skeptical of the design. He had some valid gripes (the berm was too high, for one, so it immediately developed a large scarp), but I suppose he also just sort of enjoyed poking the Corps (don't we all?).

Most folks walking the beach last Sunday (the last day of winter), probably had no idea of the beach's history. I don't recall if the park has any interpretive signs showing the 1930s construction or the engineers standing below the towering bulkhead in the 1970s.

There's more about Lincoln Park - it's relationship with the sandier Fauntleroy Cove to the south, the asymmetry of the north and south beaches, and the heavily developed shoreline to the north of the Park along Beach Drive (which is also the story of the uplifted terrace of the Seattle Fault). Maybe another time.





Tuesday, March 21, 2017

Sculpture Park



Some beaches change all the time. Or at least you can be pretty sure that if you haven't been there in while, it will be different when you come back. This beach isn't one of those. It has few degrees of freedom - admittedly, that was a key point of its design. It's the beach equivalent of putting a wide-ranging predator in a small enclosure in an old-fashioned zoo. Not very authentic, but much easier to manage.

AERIAL VIEW

The sediment is all nicely sorted gravel. Which means the beachface remains the same in both shape and texture. The coarse gravel also tends to stay high on the beach - it has less tendency to want to get lost offshore (ignoring stone-throwing children). The two rock groins assure that no material escapes and therefore the beach volume and position don't change. The groins also constrain the small opening of the beach to Elliott Bay which assures that the wave regime is limited and the beach can't shift back and forth too much in its cage.

I love this little beach and wish we could incorporate beaches into our urban shorelines more often. But I also think it is a good reminder that we shouldn't confuse domesticated beaches for wild ones. On the surface, they may look similar, but the domestic ones are more predictable and as a result, may have a little less character.


Monday, January 23, 2017

Second Beach




Vancouver has many small pocket beaches that face westward out into the bay and I've probably posted from most of them by now (a few links below). Second Beach, in Stanley Park is yet another of these. Like the others, it has been enhanced by the construction of structures that help maintain the pocket and also probably by the addition of sediment at some point.

AERIAL VIEW
Second Beach lies just east of the big pool (frozen over on this trip) which looks as if it was probably constructed out over the foreshore. This improves the configuration of the shoreline for the beach itself. There's also a rock groin at the east end which keeps Second Beach from spilling around the corner and joining the much larger, but similarly aligned, First Beach (but which is usually called English Bay Beach).

English Bay: December 2014
Third Beach: April 2007
Sunset Beach: August 2016
Kitsilano: April 2016
Jericho Beach: August 2008
Ambleside: October 2011

The Stanley Park seawall west of the Second Beach pool


Stearman Beach



Much of West Vancouver's western shoreline has a bedrock foundation, with scattered beaches where favored by shoreline configuration and stream mouths. Stearman Beach is at one of these stream mouths. It and other nearby streams (Cypress Creek, just east, is considerably larger) have built small deltas and a broad gravelly foreshore, which provides sediment and elevation for the beaches (albeit small and irregular beaches).


AERIAL VIEW

The homes that look out over Stearman Beach are relatively modest, at least compared to many of the others along West Vancouver's shoreline. The ones here all have glass railings - providing for views while discouraging the curious from clambering over their seawalls.




Dundarave



I posted from here back in October 2011 and then again just this past year, in April 2016. I like the broad western view out into the Strait of Georgia, always dotted with large ships waiting to pick up Canadian stuff to take to Asia (or at least I think that's what they're doing) and the east view back towards Vancouver and Stanley Park.


AERIAL VIEW

But mainly I like the two contrasting beaches on each side of the jetty. The simple gravel pocket beach built up against the west side and the wonderful little sand-on-the-steps beach on the lee side.




Sunday, January 22, 2017

Bayview State Park


Bayview is just down the road from the Padilla Bay Reserve and an easy place to check out during a short lunch break. Although I knew there was work planned here, I was never clear just what was going to be done - or even just what problem was to be solved. Not that this site hasn't had problems - the inevitable consequence of it's artificial creation many decades ago, it's rectangular footprint, and it's unnatural projection out into the bay.

AERIAL VIEW

Here's a post from a few years ago - Bayview: January 2012 - which may provide some hints as to the recent work. Previously, two terminal groins and two intermediate groins maintained a nourished beach on the western edge of this rectangular pad of historic fill.

The new project has removed the intermediate groins, enlarged the terminal groins, and added a lot of gravel. The beach at the south end of the site, which never amounted to much, has been significantly enhanced with gravel and logs. And the backshore has been improved with plantings and some effort to manage beach access points.

Overall, it looks pretty good. The end corners, where much extra sediment was placed, will continue to adjust -- and I suspect the additional material was placed with this in mind. We'll keep watching.








Blaine


Marine Park lies just south of the Peace Arch in Blaine. I posted from here in January 2010 and again in April 2016. The peninsula on which the wharf district is built was created largely (entirely?) from dredged material (though probably of different vintages). The outer (northwestern) edge had been armored with rock and concrete and a variety of old debris, resulting in nice views, but an ugly shoreline where access to the water can be hazardous.

The one exception was a small beach that had formed where the ragged edge of the peninsula happened to offer an appropriate configuration. But this actually provides a very nice template for future work - since it shows what orientation, what sediment size, and what beach and berm profile works best. The best model for a created beach is the beach next door!

AERIAL VIEW

A couple of years ago the city began resculpting the edge and created a pocket beach. They improved the rock work at a couple of small promontories, excavated the rock and fill between them, and added gravel. Orientation is key on these pocket beaches and this one may still be adjusting. The mobile sand and gravel is wanting to stay in the northeastern half of the little cove, leaving the western end a steeper slope of coarse cobble and rock, but it looks like overall the project has worked out well.

This project was limited to just one segment of shoreline, but it sounds like there's interest in extending this approach to additional segments in the future. You still need rocky hard points to anchor and contain the beaches, but the rock need not be old construction debris. And most of the shoreline can be a series of small beaches.




Saturday, January 21, 2017

Semiahmoo Spit

Semiahmoo Spit reaches north across the mouth of Drayton Harbor - with a long narrow neck and a very broad bulb at its distal end. This large expanse was created when the marina was dredged and the dredge "spoil" was used to greatly increase the size and elevation of the spit.


AERIAL VIEW

The perimeter of the spit consists of an irregular pattern of modest banks eroded into the dredged material and low depositional segments likely formed by the gradual redistribution of material along the shoreline. That means much of this shoreline is constructed, yet behaves much as a natural beach. And other than at the neck of the spit itself (see below), there's been no need to armor the beach.  


After numerous delays, a new phase of development is occurring on the outer edge of the spit, south of the existing resort. Fortunately, the development maintains a public trail system along the shore and has placed the new buildings fairly far back from the edge. Rather than try to fight the chronic erosion, the designers pulled the abrupt edge landward, creating more beach-like area. I say beach-like, because it's still fairly high and steep compared to a natural upper beach.


It looks great, but bears watching. The underlying reasons some segments of this shoreline were receding have not changed by reducing the height of the bank (any more than armoring an eroding bluff prevents the ongoing erosion of the beach itself). So we may find that the new beach continues to erode, probably as a low scarp. And ironically, by reducing the height of the eroding "bluff" we may have reduced the supply of sediment to the beach, which could result in more rapid erosion.

Again, this bears watching. If erosion continues, this might be a good place to consider a localized feed source - a periodically restocked pile of gravel that can meter out sediment to adjacent shorelines as it erodes.  On the other hand, maybe this won't be necessary. And regardless, kudos to Blaine and the development and their designers for what they've done here. In another era, this would have all been riprap.

Speaking of riprap, the real problem at Semiahmoo is the neck of the spit (aside from the clever idea to build a destination resort on a sand spit). Narrow and low - armored on both sides - the roadway is increasingly a causeway. And increasingly vulnerable - even at today's sea levels. (No pictures this trip - maybe next time). There have been some efforts to rebuild a berm on the inside (low energy, marshy), but they may need to be more ambitious. And the outside may require some serious thinking - maybe a coarse gravel cobble revetment of some sort?  It probably won't be easy or cheap, though maybe throwing some coarse gravel at the south end would be a useful experiment?

Previous posts from Semiahmoo:
Tongue Point: March 2009
Semiahmoo: March 2009

Thursday, January 19, 2017

Birch Bay

The north end of Birch Bay was once a marked by a large complex of spits and marshes. Drift was eastward into the bay, carrying sediment from Birch Point to form a series of spits that terminated in an inlet at the northern corner of the bay. The spits and marshes probably recorded a wonderful chronology of sea level change, geologic events, and early first nations occupation.

AERIAL VIEW



In the late 1960s, it all became Birch Bay Village. The wetlands were dredged to create lakes and a marina. The sediment was used to create dry land for homes and golf. A new inlet to the new marina was cut at the base of the spit and the old inlet was left to drain a very small remnant of the original marsh. Drift rapidly built a broad fillet against the west jetty and the downdrift beaches were starved of their natural source of material (though sediment dredged from the inlet is now periodically bypassed to those beaches). Wolf Bauer and Maury Schwartz both used Birch Bay Village as an example of what not to do to beaches.

These pictures were taken at the inlet and near the west end, where the bluff ends and the spit begins. They show the beach west of the inlet, the jetties, the seawalls east of the inlet, and a remarkably large rock buttress on the first bluff property to the west.







Wednesday, January 18, 2017

Gulf Road


A cold, clear day at the southern end of the Strait of Georgia. The wind was blowing out of the Fraser Valley but that meant this section of southwest facing beach was remarkably calm (farther south, Mukilteo and Edmonds were getting hammered by waves).

Gulf Road ends at this wonderful little stretch of beach, just south of Cherry Point. While there are bluffs in the distance in both directions, this section is a barrier beach with a nice back-barrier wetland, fed by two small streams. An old conveyor extends across the beach, dating to some unknown (by me) operation decades ago.

The roadway is eroding - as roadways on beach berms usually do. It would be neat if they could rethink this shoreline a little - maybe remove the road prism from the berm, restore the altered parts of the wetland, and make some simple public improvements - restrooms, some interpretive signage, some trails.

This shoreline reach extends from Point Whitehorn at the north, south to Sandy Point, a large, heavily developed spit that extends south into Lummi Bay. Sediment transport (beach transport, at least, I can't speak for finer grained sediment farther offshore) has always been a little controversial here. South winds are common, but the influence of a very large fetch to the north is significant and may be more important for drift.  I mentioned this in a previous post from Point Whitehorn (March 2015).

AERIAL VIEW

There are three major industries along this shoreline -- a refinery (BP) to the north and another refinery (Phillips) and an aluminum plant (Intalco) to the south. The recently proposed Gateway Pacific Terminal, which was set back by the Corps last spring, would have extended offshore just north, between this site and the BP pier in the distance.

Previous post from here:
Gulf Road: March 2010