WIXON DOCK - CONSIDERATION FOR RECONSTRUCTION
REPORT OF THE HARBORMASTER
This report is prepared by the Harbormaster to recommend what type of structure should be used to replace the Wixon Dock at the Herring River. The existing fixed dock has been in place for more than 60 years, is currently unsafe and is in need of immediate replacement. This report submitted March 30, 2010 by Tom Leach, Harbormaster.
Article in Town warrant reads:
REPLACE WIXON DOCK
To see if the Town will raise and appropriate a sufficient sum of money to replace the Capt. Nathanial Wixon Dock off Harbor Road, and to act fully thereon. By request of the Harbormaster.
The estimate from engineering is $38,400 for this replacement.
The pier and structure have a long history for commercial fishing in Harwich. A commemorative bronze plaque placed by the Town at Capt. Wixon Landing reads as follows:
Capt. Nathaniel Wixon Dock
“This land is given in faith to the citizens of the Town of Harwich to preserve a place for commercial fishermen to land their catch, moor and launch their boats as the fishermen have done for generations at the Herring River.
The property shall be used primarily as a facility for commercial fishing purposes. Priority is given to commercial fishing boats seeking to use the facility, as intended in the Gift of Land. The use of this facility by pleasure craft is allowed so long as said use does not interfere unreasonably with the primary commercial fishing use.
Paul F. Derick and Delia West, of the historic Wixon fishing family gave this property to the Town of Harwich in loving memory of the late Nathanial H. Wixon, 1896-1970”.
NEED OF STRUCTURE
The Wixon dock is one of only two public access points that Harwich has to the water on the Herring River. It provides valuable landing and deep water access to Nantucket for pleasure craft on the river, however, freshwater and electricity is not available. This structure serves many needs including operation of a handful of commercial fishermen who still take on ice and bait from the facility for blue fin tuna fishing.
Other boaters who may utilize the dock and its associated float include kayak users, picnickers and rod & real fishermen, including grandparents and grandchildren who are learning to fish or wet a line after dinner. A use not recommended for the facility, but happen commonly are teenagers swimming and diving from the pier and float. This might present a liability and the existing structure, because it offers itself as a substantial deck, encourages the use by the last named group.
What Dock Type should we have?
The first question to consider when selecting a dock type is whether you want a permanent dock or removable dock. In harsh winter climates as in the northeast a dock that can be pulled completely out of the water for the winter is common. Ice has a tendency to shift over the course of the season. If ice is allowed to form around a fixed dock, when it shifts it can cause a few different types of damage. Jacking/lifting damage happens when water levels below the ice fluctuate and force the ice that has attached to your boat or dock upward. This can loosen, or even completely remove even deep set pilings. Expansion damage is caused by the expansion of ice as it thickens (the same volume of water takes up more space when it freezes due to the expansion of the water molecules).
There are four basic types of docks: floating docks: pipe docks; crib docks; pile docks. While the first three aforementioned types can be used seasonally, it is only the pile dock that is authorized for use in the V-Zone under the US Army Corps of Engineers standards.
If we consider building a seasonal dock using a stub pile or pipe pile structure with seasonal frames and decking, the costs of re-setting and dismantling the structure seasonally will exceed the cost of a permanent structure within fifteen years. Further, this type structure may not be strong enough to withstand the forces of tide at this site over time as this is in the velocity zone. Another consideration is that it is important this landing, as any public access, is available and among the first made useful by early spring as this is the only public access point below the bridge for boaters. Assembling frames and decking is a painstaking chore that may not go smoothly if the foundation stubs become damaged or washed out. Or consider there not being enough manpower available within the department to do the job.
It is very important to consider a structure that can withstand the strong current at that spot. Current on the Herring River at this spot can exceed 3 knots during peak ebb and flood.
During winter, this strong current can also move thick sheets of ice down the river which can wreak havoc on small docks. By way of example, neighbors along the river over many years have reported seeing entire docks ripped from the bottom by six inches of salt ice. For this reason, all the associated dock floats and gangways must be removed to high ground for storage in the winter. Further, support pilings must be of adequate size and washed deep or driven to refusal. We wood recommend a type class B piling for this project.
The Town Engineer has already prepared a preliminary drawing whose basis is the town dock at Route 28, near the Weather Deck Restaurant as a format. The town already has a fully adequate design based on the Route 28 structure. We also believe this is the most economic. Fig.1
Three changes are recommended. First a narrower more affordable structure at 4’ wide (maximum width for a dock allowed in the By-Law) which would allow movement of a handcart etc., up and down the pier. Secondly, the landward end of the existing structure currently can be awash at high tide (see fig. 4.), therefore, the pier or ramp to the pier on the landward end would be longer to get near the road. Third, the deck would be lower in elevation by one foot thereby reducing the severity of the angle of the gangway to the float.
The pier serves about one-half of the 35 boaters on the lower river who need something substantial to pull up to. The rest of the group use there private dock or are residents of Old Mill Point. It serves kayakers launching and retrieving their small kayaks from the small beach to the immediate north. They can walk there kayaks to the float using the kayak painter if they wish. This will not change.
Although some people have attempted to launch here, this is not a boat ramp along side this structure. The area has little or no parking, maybe two spots. Parking on the pavement that is Harbor Road, risks a parking citation from the Harwich Polices Department. Also, launching jet-skis there is prohibited by the Harwich Protective By-Laws which imposes a $200 fine for operating a personal watercraft on Herring River.
In addition to the aforementioned boaters moored who have no alternative to use the public landing, the Wixon pier itself and land was gifted to serve fishermen and to make it easier for them to land catch. The BOS seem to want a widened structure to provide a viewing stand or bench. Widening the structure will substantially add to the cost. A structure of this type will run in the $120/sq ft. neighborhood on the bid or $38,400.
The following information is excerpted from the Town of Harwich, Harbors & Marine Facilities Analysis report. The report basically says the existing structure is not worth repairing and should be replaced with one that meets building code requirements.
6.2 Nathanial Wixon Pier and Float
6.2.1 Description of Facility
The Wixon Pier is a typical wooden pile-supported structure with a wood deck and an aluminum ramp leading to a wooden float and is located at the end of Harbor Road. The pier has a total length of approximately 45 feet and a varied width of 4.75 feet to 11.5 feet (327 SF). Piles are constructed with 8 bents with 3-5rows of 2” x 8” stringers every two feet on center along the pier. There are (2) 2” x 8” headers located at each pile bent. All lumber for structural components appear to be pressure treated southern yellow pine. The decking consists of 2”x8” plank decking with ½” spacing. Piles range from 10”-12” in diameter (approx. 18 total) and are pressure treated.
The side railings are measured at 2”x4” members. Also, utility and water conduits are not present under the pier. The attached floating dock is approximately 200 SF (10’x20’) and the aluminum ramp is 12’x3’. The ramp is connected to the pier by means of roller connection.
6.2.2 Observed Conditions
A modified level III inspection was done on the pier. A walk-around was done to inspect piles, wood deck, cleats, float, ramp and overall general condition. All piles tested were scraped and measured by circumference at two locations per test. Please see field reports and photographs for a detail of the actual inspection results. The stringers, headers, and main structural members of the pier are in deplorable condition and are unsuitable for their specific function. The majority of the piles are deteriorating to the point where they are breaking apart. The piles are disease stricken, weathered, and infested with marine borer organisms. CEC has presumed that the main reason for this breakdown is due to biological deterioration. Various piles have an “hour-glass” shape, which clearly indicates the presence of the crustacean family of marine borers. These wood borer organisms such as Limnoria, Sphaeroma, and Chelura form networks of interlacing tunnels that easily erode the inner cavity of the pile. Once the pile becomes eroded, it creates a susceptible environment for waves to eat away at the pile. Not all
of the piles of the pier are showing such grim deterioration; however, they are still experiencing biological infestation and continue to erode and lose crucial pile circumference that is required to withstand waves and pier generated loading.
The size of the members is also another concern in regard to current building code requirements that relate to dead and live loads. A 2”x8” header is not sufficient for a town pier of this magnitude and should at least be upgraded to a 3”x10”. Existing connective hardware is not sufficient, as some through bolting is inappropriately placed.
Lastly, the ramp and float are in good condition and are not in need of replacement at this time. The piles and connections are all sound and remain to be in good condition. All hardware of the float system is in good condition and does not show signs of corrosion as of yet. The pier should be monitored every year to assess any maintenance or safety issues that need to be addressed.
6.2.3 Structural Condition Assessment of existing Wixon Dock
When considering the amount of time and effort required to provide maintenance to this pier on an as needed basis, it is economically unfeasible to provide sacrificial or maintenance repairs to the pier at this time. The pier has endured a great deal of deterioration and weathering. CEC recommends that the pier be removed and replaced in kind as soon as possible. The pier, as it stands, is extremely vulnerable to wave or wind action. Also, if a large group of individuals congregate on the pier, it could potentially collapse at any time. There is a major safety risk posed with this pier and it should be addressed as soon as time permits.
There are substantial shifts in horizontal and vertical alignment of the pier, as well as major deterioration of the bearing piles. The stringers, headers, and decking have endured substantial biological and functional damage over the years. The sizing of the members is also unsuitable for current design loads. In addition, rusted and missing components, and corrosion are hindering the piers ability to function as it should.
CEC makes the following recommendations regarding the Herring River Wixon Pier. These recommendations should be incorporated into a maintenance plan that addresses the following issues:
What is missed in this Town of Harwich, Harbors & Marine Facilities Analysis Report from Coastal Engineering is a description of an ancient bulkhead made from locust trees used as pilings(these are also used as weir poles) which forms a sub-tidal bound on the east end of the property. This structure was discovered by Charles Beggs of Ames Marine Service, Inc. of Harwich when they were hired to remove the old barn, and its underpinnings, that was attached immediately on the south side of the exiting structure after it was destroyed by Hurricane Bob (1991). Beggs shored up the existing dock and drove the guide pilings and added the aluminum gangway that is used today.
Fig. 4. The Old Wixon Dock. The barn and its support framing were removed after damage caused by Hurricane Bob in 1991. The dock to the left of barn and some outer pier deck remain today but are now unsafe. Note tidal water surrounds entire structure in this photo.
The ancient bulkhead, it is believed, was driven by Capt. Nathanial Wixon who operated a fish weir-trap operation from the structure into the 1960’s. The bulkhead is now wash-over meaning that the exposed part of those locust pilings have since disappeared due to withering of boring worms on the exposed parts and the harsh force of ice damage. However, we believe that this bulkhead still serves to stabilize the property. This bulkhead is clearly visible in the olld postcard at rthe end of this report (Fig 5.).
If this ancient bulkhead were removed, it is nearly certain the current and back eddy caused by the adjacent bulkhead to the north would undercut the landing property. This structure also precludes consideration for re-positioning a new dock. The thought was to move the structure ten (10) feet south for better alignment with the guide pilings that hold the float. This would expose the old pier bents which should necessarily be removed. However, it would also mean that the soft ramp to the north could not be brought closer to the new pier due to the wash-over “bulkhead”. For this reason, the pier would have to go in the same spot and instead the guide piles should be relocated a bit to the north for better alignment with the dock.
If Harwich were to give up this pier it would lose public access to the water.
Under the circumstances a pile supported pier is the most economic and reliable structure for this unstable area.
Fig 5. An old postcard showing the Wixon Landing. Erosion in the area must have neenn a problem. Note the ancient improvised bulkhead made of locus trees. Also there may have been three or even four shanties along this area on the west bank of the Herring River. Note the position of Harbor Road.