Tuesday, August 30, 2011

A Whole New River Just Around the Bend...

Like sleeping giants, a stretch of intriguing
boulders are emerging as the river below
Rhodes-on-the-Pawtuxet lowers to its new levels.

At high tide last Friday evening, the natural
flows and sounds of the river, no longer tethered
by its old spillway, were a wonderful validation
of this restoration project.

Looking through the Broad Street bridge and
across Pawtuxet Cove at high tide, the
connection between river and bay now
appears seamless.

Friday, August 26, 2011

Going, Going, Gone

Work continued Thursday on the Southernmost section of the dam.
In advance of this weekend's storm, the Sumco crew is working feverishly, both chipping away at the remaining concrete and removing the debris from the site. The project team has been in communication with RIEMA and the municipalities, providing assurances that, by the end of Friday, all equipment and debris will be out of the river.
The final photo in this series taken Thursday evening at high tide shows the free flowing river and the best evidence yet of the potential for successful passage between river and the bay - for fish and paddlers!

Wednesday, August 24, 2011

More River, Less Dam

Yesterday and today, SumCo worked on removing the south spillway, beginning at its north end where it tied into the big ledge outcrop in the middle of the river. At noon today, they began pulling back the cofferdam and allowing the river to flow over that section of the bedrock. They also finished up the low-flow channel in the riverbed between the dam site and the bridge. The river is really coming down now. Meanwhile, we're following the track of Hurricane Irene and will pull all the equipment and rubble out of the river before the storm arrives. Here's a video from today--Travis and Arthur pulling a sandbag to allow the river to flow over the bedrock in this location, perhaps for the first time in 200 years. Within a day or two, the river upstream of the dam location will be feeling the tides from Pawtuxet Cove, again likely for the first time in centuries.

Tuesday, August 23, 2011

Cutting the Low Flow Channel

Today Dick Quinn from US Fish & Wildlife was on site, working with Curt Mason of EA Engineers to cut a low-flow channel in the river bed along the south bank of the river. Its purpose is to ensure that even if river flows are unusually low during the spring fish run period, shad and herring will be able to swim upstream over the restored Falls. Flows were relatively low today and we took advantage of low tide in the morning. The first photo shows Dick at work with Arthur, one of the guys from
SumCo, to lay out the channel. Later they had two excavators working--one on the channel and one on the dam. Removal of the south spillway is moving slowly due to the mass of concrete that must be removed, and because this spillway, unlike the center section, is crisscrossed with steel reinforcing rods. The second photo shows both machines at work.

Monday, August 22, 2011

Monday Afternoon

Conditions look good this week, with relatively low flows and low tide during the day. SumCo spent the morning pulling back rubble left from demolition of the center spillway, and is now back at work continuing the demolition of the south spillway. This section of the dam is much more massive than the last; its demolition should take the better part of the week--if we don't get any rain and flows stay low. Following the demolition, SumCo will remove all concrete rubble from the river, filling steel containers to be hauled out by crane. Here's what it looks like now. The orange turbidity curtain is in place to prevent concrete dust from the demolition from moving downstream with the current.

Media Coverage

The project has received much attention in the media lately. On Friday evening channel 10 (WJAR) covered the project.

The Providence Journal wrote an article titled Pawtuxet Falls project is biggest dam removal job in R.I. history
EcoRI has also covered the project. Click here to read the article. 
And if you haven't had the chance yet, be sure to get down to the river check out the dam destruction for yourself!

Wednesday, August 17, 2011

Video from Wednesday

The flows are still too high to get back to work. Here's video from this morning.

If you compare this with the videos from last week, you'll see that as the dam removal got underway, the river was flowing over the bedrock and through the slot in the south spillway. Now it has risen to the point where it is again flowing over the north and south spillways. Hopefully it'll be down enough by tomorrow that SumCo can get back in the water.

You can check out the river's flow in real time, courtesy of USGS, by clicking here

A Lesson in Hydrology

This project on the Pawtuxet River has been a good lesson in watershed hydrology. As the work crew was at the site on Monday, preparing water control for removal of the last section of dam, rain was falling steadily and water levels rose as they were working. It became clear by the middle of the day that there would be no more work in the river until water levels fell.

Looking at this hydrograph from the USGS gage in Cranston, you can see the flashy nature of this river system and how it responds to rain events. The first rain event we had on Sunday, August 7th, rose water levels to over 800 cfs. Flows were also being manipulated by a hydro operation upstream. The several inches of rain we had on Monday were enough to increase flow from under 200 cfs to over 1,000 cfs within a few hours. Because the watershed is so large, flows have still not dropped substantially two days later. Some of this is due to the fact that the Scituate reservoir is now full and is spilling over its dam. Flows on Monday were the highest for that day since August 15th 1973 when a flow of 827 cfs was recorded at the Cranston gage.

Rivers respond to what is happening in the watershed. A large amount of impervious surface causes quick rises in river flow. Manipulation from dams and other human influences also cause flow fluctuations putting added stress on the river's ecology and built environment. When flows reach around 500 cfs, we will see the crew back at work on the last section of dam.

Tuesday, August 16, 2011

RI DEM Testing of the Lower Pawtuxet

On the evening of August 10th, Alan Libby from DEM's Fish & Wildlife Division, took his team of four for a trip up river from the Pawtuxet Falls dam to assess the prevalence and variety of fish currently in the river. For the 2 mile section that they examined, they found the following in order of abundance: white sucker, golden shiner, American eel, brown bullhead, pumpkinseed, common carp, yellow bullhead, bluegill, and largemouth bass. By far the most prevalent fish was the white sucker. All fish caught during the sampling appeared healthy according to the team, and are also found in other parts of the Pawtuxet system. No anadromous fish were found, however, including the herring and shad that are target species of this project.

Such testing of the lower Pawtuxet has not been done since the late 90s. With the work completed last week, we now have a baseline for evaluating the primary impact of the dam removal. DEM will continue to conduct annual assessments to measure the degree and rate of restoration of anadromous fish to this river. If resources permit, some stocking of the Lower Pawtuxet will take place to help accelerate the process.

Friday, August 12, 2011

Friday Afternoon--Center Spillway Out

Friday was our fourth day in the water at Pawtuxet Falls. The SumCo crew has completed removal of the center spillway section, and is working back toward the south or Warwick end of the dam where work began on Tuesday. The upstream pond created by the dam is dropping, flowing over the natural bedrock falls which lay beneath the dam, and is now exposed--perhaps for the first time in 200 years. Here's a video from Friday afternoon.

It was an eventful week, obviously. Work went slowly at first due to the fact that river flows were much higher than we would have liked, due to rain over the weekend and
hydro operations upstream. By the end of the week, flows were down considerably and SumCo made great progress. We d
iscovered that the center spillway had less concrete, and more rock, than expected, which was a pleasant surprise for several reasons--since the contractor is only removing the concrete, it meant the work went faster; while the height and irregularity of the bedrock will make for an interesting natural falls once the spillway is fully out.

SumCo's approach to removing the dam was to place large steel plates against
the upstream side of it; cut notches downstream of the plates; then manipulate the plates to control the rate at which the river is allowed to reach its restored level. This photo shows one of the plates in place in the center spillway section just upstream of the work area, as the excavator removes concrete rubble that was hammered away from the concrete spillway with a 1500 pound hydraulic hammer.

There was quite a crowd on Broad Street Bridge all week, watching the work. Mostly interested neighbors and other members of the public; nearly everyone I spoke with was enthusiastic about the restoration. Project partners

showed up, too--the permitting crew from DEM, engineers from NRCS, and partners from Save The Bay and NOAA. Senator Josh Miller and Rep. Joe McNamara stopped by; both were instrumental in helping with the legislative work necessary to make the project a reality. Here's what the bridge looked like for much of the week.

Travis Sumner of SumCo Eco-Contracting was running the excavator and the construction crew all week. He and his guys are just remarkably skilled and dedicated. They worked all week in the waist- or even chest-deep water. Travis seems to be able to drive the excavator over or through anything. In skilled hands, an excavator bucket is an amazing thing--able to lift and position a two-ton sand

bag, or move a rock a couple of inches. Whether walking the machine up a slope using the hydraulic arm like a giant leg or perched at a crazy angle moving rubble, Travis was clearly in full control of the machine, and the crowd on the bridge was suitably impressed.

SumCo may continue work tomorrow, and resume again on Monday--there's a chance of rain on Sunday, so we'll see what the flows look like then.

Video from Thursday morning

More of the dam came out on Thursday as crews continued to work with the hydraulic hammer. Later in the day, the steel plates were removed and water flowed through the newly opened section. Many more photos are available on the Save The Bay Facebook page.

Wednesday, August 10, 2011

Video from Wednesday's Activities

Below is a short video of the hydraulic hammer at work on the northern section of the dam. Water levels continue to be higher than anticipated, but this notch cut in the dam should help bring water levels down.

Dam Removal Begins with River Levels High

With the recent rains, the flow of the Pawtuxet River is much higher than anticipated, and construction crews are working to lower water levels as they begin to remove the dam. Two notches were carved out of the dam on Tuesday and Wednesday, and sandbags and steel plates are being used to control water levels. The river will not be drawn down more than 6 inches a day. In a few days, we should see more of the dam exposed. In these photos from today, you can see the hydraulic hammer working on the northern portion of the dam. A notch was cut in the southern part of the dam on Tuesday.

Thursday, August 4, 2011

Mobilization This Week

We're mobilizing for the dam removal this week. Access agreements are completed and SumCo, our construction contractor, is preparing the staging areas today--beginning with tree removal and site clearing at Hunter's Garage and installation of a temporary boatramp at Rhodes-On-The-Pawtuxet. We're working with DEM to finalize water control plans; once those are approved, SumCo can get in the water. Stay tuned for pictures later today & tomorrow.

Thursday, July 21, 2011

Current Conditions at Pawtuxet Falls Dam

Construction, or rather destruction, is about to begin on the Pawtuxet Falls Dam. The Pawtuxet River Authority, along with its partners will be removing sections of the dam to restore the connectivity between the river and the Narragansett Bay. Today, obsolete dams prevent the fish from returning to their historic spawning grounds. Restoring the connectivity will allow migratory fish to return to their historic spawning grounds. For thousands of years, great schools of herring and shad swam upstream from Narragansett Bay each spring to spawn in the streams, lakes and ponds of the Pawtuxet watershed.
These sections of the Pawtuxet Falls Dam will be removed.
The project partners will be monitoring the construction process and posting pictures and information as the construction crew removes sections of the dam and plants new vegetation along the banks. Become a follower and stay up-to-date on the process!
Panoramic view of both sections of dam to be removed.