AGENDA DATE: 7/5/2018
TITLE:
Title
Hollymead Dam Spillway Improvements
BODY
SUBJECT/PROPOSAL/REQUEST: Adoption of Resolution supporting the temporary closure of Northbound Lane of Timberwood Parkway (Rt 1521) at Lake Hollymead Dam during construction of Lake Hollymead Dam Spillway Improvements.
ITEM TYPE: Consent Action Item
STAFF CONTACT(S): Walker, Henry, Kamptner, Abplanalp
PRESENTER (S): Blake Abplanalp
LEGAL REVIEW: Yes
REVIEWED BY: Doug Walker
BACKGROUND: The scope of work for Hollymead Dam Spillway Improvement project affected by this request includes:
• improvements to the primary spillway at water’s edge of Lake Hollymead Dam
• construction of concrete walls along the crest of the dam to direct a modeled
• overtopping event to the center, lowest portion of roadway
• a new concrete outlet structure
• and concrete mat installation on the downslope face of the dam to armor and protect against failure in event of extreme high water (modeled at 5.6’ higher than lowest point in road).
This project was recently advertised. Construction is scheduled to begin in mid to late August, with road closure effective the first week of September. Based on this schedule, the construction of dam spillway improvements could commence in September 2018, with need for one-lane road closure extending through April 2019, but not beyond without Board and VDOT extension of Maintenance of Traffic Plan (MOT Plan) temporary road closure with detour to US Rt. 29.
STRATEGIC PLAN: Infrastructure Investment: Prioritize, plan, and invest in critical infrastructure that respond to past and future and improves the capacity to serve community needs
DISCUSSION: The scope of work requires uninterrupted construction for a period anticipated to last eight (8) months, once contractor mobilizes. The guardrail that extends along the east edge of Timberwood Parkway along the crest of the dam will be removed. An MOT Plan (under development) will likely recommend jersey barriers as a temporary fixed centerline protective device for southbound vehicles, to isolate construction zone and limit possibility of off-road event once guardrail on the east side is removed. Guardrail on the west (lakeside) of the road will remain in place for the duration of project.
FES /PMD anticipates the Engineer (Kimley-Horn Assoc.) and VDOT are inclined to favor one lane, northbound-only road closure detour via Hollymead Drive to US Rt. 29, to Timberwood Boulevard, to reconnect with secondary streets north of the dam. Northbound traffic will use this detour upon approach to the dam. Southbound traffic on Timberwood Parkway may cross the dam safely, with physical separation from construction.
The MOT Plan may account for brief intermittent periods of material delivery or construction activity that requires contractor to halt southbound traffic, as well, using hand paddles or approved signaling equipment. The northbound detour may remain in place for eight (8) months. County Fire/Rescue, Police, and Schools (Director of Transportation) appreciate the need for safety, and signal willingness to coordinate and work with PMD as time of closure approaches. These agencies are aware of plans for one lane northbound-only road closure, with provision that allows emergency vehicles to cross in the northbound direction (sirens would alert oncoming motorists). The length of road closure is approximately 600’ and given narrow width of southbound lane during construction, it remains to be seen whether plan for southbound traffic to yield to oncoming emergency response vehicles is workable. In any event, Fire /Rescue and Police will share temporary road closure information with response personnel, such that there is minimal appreciable delay in rescue response in either direction.
Alternatives:
• Two-way (two lane) traffic allowed, with frequent disruption of traffic in both directions via contractor personnel use of stop-slow paddles to allow cranes, trucks, or heavy equipment to position, deliver, grade, or otherwise engage in routine activity. With this option, there would be no physical barrier to prevent a car exiting the roadway and traveling down the dam face to stream below, across an active sloped construction site. Also, with this option, if traffic approaches from the south, traveling north, and does not detour to U.S. Rt. 29, the traffic circle at Powell Creek Drive and Shadybrook Trail is blocked, and non-functional. Vehicles exiting the 126-unit development served by Shadybrook Trail have only a single outlet. If two-way (two lane) traffic is maintained, then apart from safety concerns with proximity of construction, vehicles trying to exit Shadybrook Trail, in either direction, north or south, will be delayed until their turn, at which point, all north /southbound Timberwood Parkway must halt to allow Shadybrook traffic to access the traffic circle at Powell Creek Drive (see Attached Exhibit).
• Two-way (one lane) traffic allowed, with alternating movement and frequent full stop of traffic in the opposing direction. This option, with full-stop intervals, disrupts all traffic movement daily for many months, imposing wage rate expense of two or more full-time certified contractor personnel to control traffic movement. This option voids possibility of quick fire-rescue crossings, as traffic will routinely back up, in one direction or the other. The preferred option provides possibility of unimpeded southbound emergency response, siren-alert northbound emergency response crossing, keeps open Shadybrook Trail development entry /exit point at the traffic circle (unchanged from existing condition), and saves the County considerable pass-through expense of additional contractor personnel. This alternative, by closing northbound lane to traffic with likely centerline jersey barrier protection, at least provides a one-lane buffer between vehicles and active construction.
Both alternatives listed above impose a frequent full-stop condition in each direction, isolate the Shadybrook Trail community, impose avoidable costs, limit fire-rescue access /response, and do not allow drivers to acclimate to fixed conditions during construction. A detour to Rt. 29 would allow southbound traffic to acclimate to slower speed, with no other change; would allow northbound traffic to learn detour route to Rt. 29, then north to Timberwood Boulevard. The detour, depending on points of departure and destination, time of day, and signals on Rt. 29, may add ten minutes travel time, at most. Average additional travel time, for a trip south to north via US Rt. 29 detour, would likely be less.
Project Management Division requests a one-lane northbound closure of Timberwood Parkway (Rt. 1521) between Shadybrook Trail south of the dam and Cove Pointe Road north of the dam (except for emergency traffic) for eight (8) months during construction to allow installation of dam spillway improvements. VDOT has granted permission for this detour with the following restrictions/requirements: closure of one lane only (northbound lane); maintenance of traffic in accordance with VDOT-approved Maintenance of Traffic Plan (MOT Plan), mill /pave northbound lane of Timberwood Parkway as shown on final design plans (or as needed to restore Timberwood Parkway to pre-construction condition); physical barrier between vehicles and edge of pavement along dam crest once east-side guardrail is removed; on-site periodic inspection of Maintenance of Traffic Plan signals, barriers, cones, barricades, message boards, or signs, with prompt correction of any safety or messaging device deficiency; and maintenance of the detour route, signage, and flagging as needed.
The road closure has been coordinated with Albemarle County public school Director of Transportation, with Albemarle County Fire Rescue, Albemarle County Police, and Charlottesville Residency of VDOT. One lane closure of the road would expedite the proposed Hollymead Dam Spillway improvements, and result in a safer construction work zone.
Albemarle has determined a reasonable detour to US Rt. 29 (Seminole Trail) will not place undue strain on Hollymead Drive or Timberwood Boulevard, as these surface roads are primary entry /exit points for Hollymead and Forest Lakes communities. The length and duration of detour will require adjustment by residents, commercial carriers, emergency response personnel, transportation officials, CAT and public school operators, but PMD believes a one-lane closure with free-moving southbound traffic is least disruptive while providing degree of predictability and level of safety not possible with any other alternative.
VDOT has confirmed that this route is within existing public right-of-way. PMD recommends closure of Timberwood Parkway at Hollymead Lake to northbound traffic, by maintaining one-lane unimpeded southbound traffic during construction of Hollymead Dam Spillway improvements.
BUDGET IMPACT: Adoption of the attached Resolution would help preserve project funds via contractor savings, which should reflect in bids received. Additional costs for preparing, maintaining, etc. the detour will be more than offset by the savings in flagging personnel and construction time.
RECOMMENDATION:
Recommendation
Staff recommends that the Board adopt the attached Resolution (Attachment B).
ATTACHMENTS:
A - Detour Exhibit
B - Resolution
C - VDOT Letter