Basin Specific Feasibility Studies Everglades Stormwater Program Basins Preliminary Findings
Stormwater Basin Rehabilitation: A Unique...
Transcript of Stormwater Basin Rehabilitation: A Unique...
Stormwater Basin Rehabilitation:
A Unique CollaborationBenton G. Webber, PE
Township Engineer
Lancaster Township
Devin Groff
Township Roadmaster
Bill Laudien
Township Manager
Welcome to Lancaster Township
• Formed in 1729, the Township is roughly six square miles in area with a population of roughly 17,000 and nearly 55 miles of roads.
• Creation of Lancaster City (2miles x 2 miles) and various other annexations leaves the Township with nine (9) noncontiguous areas.
• Centuries of community building that only until recently considered stormwater concerns other than drainage.
• Available sites for new development are rare.
• Aging infrastructure suffers from ownership questions, neglect, and cost constraints for upkeep.
What BMPs are we looking at?
• Basin Retrofits
• Erosive Swales
• Floodplain Restoration
• Streambank Restoration
• Riparian Buffer Plantings
Basin RetrofitsPros:
• Fix what’s broken → political will
• Possibly find other stakeholders
• Archival research may help lessen the effort of determining the BMP Effectiveness
• Public awareness
• DEP permitting
Cons:
• No guarantee of finding them
• Possible resistance from involved parties
• Ancillary problems (trash & other nuisances)
• DEP permitting
Conventional Basin from 1980s
• Located in an easement across several properties.
• Maintenance responsibilities very vague.
• Maintenance requirement citation skipped after first deed.
• Neglect leads to obscuring vegetation and basin fills in with sediment.
• Outlet structure is blocked/buried and emergency spillway is actuated regularly.
• Berm begins to erode.
August 2016
• Vegetation obscuring the basin, endwall, berm, & spillway.
• Sediment between 2’ and 3’ deep inside basin. Standing water most of the time.
• Outlet pipe completely buried and hidden.
February 2017
• Berm at spillway is failing.
The Fix• Explain to property owners
• Provide technical guidance on repairs
• Follow-up to answer questions
• Develop shared responsibility for restoration tasks
• Establish a timeline for the work
• Provide inspection during and after rehabilitation
How did we get started with the Kensington Club project?
• Call from Apartment Complex manager that a pipe in a swale had become exposed → sewer service lateral…CLAY PIPE!
• Highly eroded and deep swale
• Entire area was overgrown with vegetation
• Downstream City property owners experiencing a lot of flooding and debris. “Can you do something?” FOUND IT!
• Concrete encasement repair, first…then broach the subject of the basin
• File research produced plans from 1973
2005 image of forgotten basin of 1973
Hamilton ES - City
Kensington Club -Township
Breached berm with discharge barrel
Consensus building
• Make everyone aware, provide documents, and be available to answer questions.
• Prioritize what should happen first.
• Acknowledge property owner responsibilities, but be a partner in resolution.
• Explore grant funding and be creative about how to maximize its usage.
• Plan each step and adjust along the way.
• Keep everyone informed, even with bad news.
2018 image of forgotten basin of 1973
Survey & design plans for basin rehabilitation
Kensington Club basin - highlights
• Reduced stormwater flow rate and generation of sediment & debris
• Re-established a maintainable SWM facility
• Identified ongoing maintenance responsibilities
• Reduced Township’s sediment load by 357K# per year
• Highlighted the need for above issues with general public
• Re-created a pedestrian walkway from the apartment complex to the Elementary School
• Necessitated an informal 4-way partnership in order to leverage each stakeholder’s offerings and to reward each with proportional benefit
Everybody pitched in…
• Lancaster Township
• Kensington Club
• School District of Lancaster
• Lancaster City
• PA Department of Environmental Protection
• Lancaster County Conservation District
Township roles & responsibilities
• Measurements of 2017 field conditions for sediment rate
• Material procurement
• RCE, gravel laydown area, and site restoration
• PC and BOS approval of the SWM Site Plan
• Solicitor and bookkeeping
• Sediment reduction part of our Chesapeake Bay PRP
• Coordination, design, and project management
• Ongoing inspection obligations
Lancaster Township PWD scope on Hamilton ES property
Lancaster Township PWD
• Rock Construction Entrance
Lancaster Township PWD
• Gravel Laydown Area
School District of Lancasterroles & responsibilities
• Allowed project to be constructed partially on their property, plus a Rock Construction Entrance and gravel laydown area
• Agreed to allow ongoing maintenance of the basin
• Restricted our time for construction to the summer break
• Were very patient as the final wrap-up tasks overlapped into School being back in session
• Students participated in opening ceremony for pathway
City of Lancaster and PA DEProles & responsibilities
• City granted waiver and provided technical advice
• City has right to inspect the basin
• City benefits from reduced flow and debris
• City can take advantage of drop manhole for future swale improvements
• DEP provided $200K grant
• DEP allowed activity as a waiver
• DEP provided guidance and administrative direction for grant
September 2018 – 22 months since discovery
Five Take-Aways
• Collaboration will get more done.
• Rebuild & repair, rather than build new.
• Don’t know, if you don’t ask.
• Be on the look-out for grant opportunities.
• Even in the wettest year recently and without all the details being ironed out in advance, we can all work together to solve problems.