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WP_Query Object ( [query] => Array ( [services] => dam-and-barrier ) [query_vars] => Array ( [services] => dam-and-barrier [error] => [m] => [p] => 0 [post_parent] => [subpost] => [subpost_id] => [attachment] => [attachment_id] => 0 [name] => [pagename] => [page_id] => 0 [second] => [minute] => [hour] => [day] => 0 [monthnum] => 0 [year] => 0 [w] => 0 [category_name] => [tag] => [cat] => [tag_id] => [author] => [author_name] => [feed] => [tb] => [paged] => 1 [meta_key] => [meta_value] => [preview] => [s] => [sentence] => [title] => [fields] => all [menu_order] => [embed] => [category__in] => Array ( ) [category__not_in] => Array ( ) [category__and] => Array ( ) [post__in] => Array ( ) [post__not_in] => Array ( ) [post_name__in] => Array ( ) [tag__in] => Array ( ) [tag__not_in] => Array ( ) [tag__and] => Array ( ) [tag_slug__in] => Array ( ) [tag_slug__and] => Array ( ) [post_parent__in] => Array ( ) [post_parent__not_in] => Array ( ) [author__in] => Array ( ) [author__not_in] => Array ( ) [search_columns] => Array ( ) [ignore_sticky_posts] => [suppress_filters] => [cache_results] => 1 [update_post_term_cache] => 1 [update_menu_item_cache] => [lazy_load_term_meta] => 1 [update_post_meta_cache] => 1 [post_type] => [posts_per_page] => 10 [nopaging] => [comments_per_page] => 5 [no_found_rows] => [taxonomy] => services [term] => dam-and-barrier [order] => DESC ) [tax_query] => WP_Tax_Query Object ( [queries] => Array ( [0] => Array ( [taxonomy] => services [terms] => Array ( [0] => dam-and-barrier ) [field] => slug [operator] => IN [include_children] => 1 ) ) [relation] => AND [table_aliases:protected] => Array ( [0] => ph_term_relationships ) [queried_terms] => Array ( [services] => Array ( [terms] => Array ( [0] => dam-and-barrier ) [field] => slug ) ) [primary_table] => ph_posts [primary_id_column] => ID ) [meta_query] => WP_Meta_Query Object ( [queries] => Array ( ) [relation] => [meta_table] => [meta_id_column] => [primary_table] => [primary_id_column] => [table_aliases:protected] => Array ( ) [clauses:protected] => Array ( ) [has_or_relation:protected] => ) [date_query] => [queried_object] => WP_Term Object ( [term_id] => 1255 [name] => Dam & Barrier Removal [slug] => dam-and-barrier [term_group] => 0 [term_taxonomy_id] => 1255 [taxonomy] => services [description] => [parent] => 1254 [count] => 25 [filter] => raw [term_order] => 10 ) [queried_object_id] => 1255 [request] => SELECT SQL_CALC_FOUND_ROWS ph_posts.ID FROM ph_posts LEFT JOIN ph_term_relationships ON (ph_posts.ID = ph_term_relationships.object_id) WHERE 1=1 AND ( ph_term_relationships.term_taxonomy_id IN (1255) ) AND ((ph_posts.post_type = 'project' AND (ph_posts.post_status = 'publish' OR ph_posts.post_status = 'acf-disabled'))) GROUP BY ph_posts.ID ORDER BY ph_posts.menu_order, ph_posts.post_date DESC LIMIT 0, 10 [posts] => Array ( [0] => WP_Post Object ( [ID] => 15951 [post_author] => 1 [post_date] => 2024-11-07 18:54:42 [post_date_gmt] => 2024-11-07 18:54:42 [post_content] => The Martin Dam was constructed on an active farm in 1961 as part of USDA’s sustainable farms pond construction initiative. Martin Dam’s robust 4,000 cubic yards of placed dam material resulted in the impoundment of only 3.5 acres of surface water. Several years ago, during the removal of a beaver dam that was obstructing the dam outlet, the riser structure was inadvertently destroyed, and a large part of the earthen dam collapsed. Due to the damage, the dam was put under an enforcement action from the Maryland Department of the Environment (MDE) Dam Safety Program. Site investigations showed an outlet culvert in total disrepair and severe erosion of the dam and downstream areas. Fearing the risk to property and life from a catastrophic dam failure, GreenTrust Alliance, in partnership with Princeton Hydro, were enlisted to design, develop, and enact an emergency dam breach. The earthen dam was approximately 20 feet in height and 490 feet in length, with an impoundment of approximately 3.48 acres. The contributing drainage area was approximately 0.25 square miles (160 acres) of low density residential land use and the primary inflowing channel, Overshot Branch, was intermittent or ephemeral. The assessment and design involved probing within the impoundment, which revealed water depths averaging 4.7 feet, with a maximum of 7.5 feet, and impounded sediment depths averaging 1.0 foot, with a maximum of 3.0 feet. Princeton Hydro prepared a 35% design plan for the earthen dam removal, and this plan was subsequently approved by MDE Dam Safety with an emergency permit, forgoing the typical months-long design and review process. The dam breach was implemented in late 2018. After the dam breach, Princeton Hydro completed a hydrologic and hydraulic assessment. Pre- and post-breach conditions were modeled to determine the potential increase in flood elevations to downstream properties. In addition, a dam failure was also modeled to assess the potential risks should the dam have failed. In comparing the pre-and post-breach scenarios, 100-year flood elevations increased between 0.01 and 0.29 feet for approximately 1 mile downstream of the pond. The floodplain valley for this stream was relatively narrow which means any increases in discharge translated to larger increases on peak flood elevations compared to the total width of the floodplain. However, the narrow floodplain also acted a barrier, ensuring that flooding was mostly contained to the area around the stream itself. No additional structures were inundated as a result of the breach. Princeton Hydro, along with GreenVest and Green Trust Alliance, developed a design that enhanced in-stream habitat of the downstream reach, and allowed for passive wetland conversion and restoration of the former impoundment. [post_title] => Martin Farm Pond Emergency Dam Breach & Dam Removal [post_excerpt] => [post_status] => publish [comment_status] => closed [ping_status] => closed [post_password] => [post_name] => martin-farm-pond-emergency-dam-breach-dam-removal [to_ping] => [pinged] => [post_modified] => 2024-11-08 19:01:34 [post_modified_gmt] => 2024-11-08 19:01:34 [post_content_filtered] => [post_parent] => 0 [guid] => https://princetonhydro.com/?post_type=project&p=15951 [menu_order] => 0 [post_type] => project [post_mime_type] => [comment_count] => 0 [filter] => raw ) [1] => WP_Post Object ( [ID] => 15487 [post_author] => 1 [post_date] => 2024-08-01 05:02:56 [post_date_gmt] => 2024-08-01 05:02:56 [post_content] => Princeton Hydro was contracted to investigate, analyze, and design the removal of obstructions and restore natural stream function on Darby Creek. With funding from the National Fish and Wildlife Foundation and Pennsylvania Growing Greener program, the objective of the project was to remove remnant bridge piers in Colwyn and Sharon Hill Boroughs, a failed dam in Darby Borough, a mill dam in Landsdowne and Clifton Heights Boroughs, and a dam in Upper Darby Township and Clifton Heights Borough. The Kent Park Dam was a placed rock structure that spanned Darby Creek within Kent Park within Delaware County. Princeton Hydro prepared hydrologic and hydraulic analyses; assessed fluvial geomorphic characteristics; determined infrastructure impacts; inventoried natural resources, including wetland delineations and invasive species; and assessed impounded sediment. Design plan sets were prepared, public presentations completed, and permit applications submitted to the Pennsylvania Department of Environmental Protection, U.S. Army Corps of Engineers, and the Delaware County Soil Conservation District. This project included the reconstruction of the stream bank using bioengineered soil lifts; the innovative construction of a riffle over a sanitary sewer line, which protruded above the stream bed; and the creation of a wetland complex within a small spring tributary to Darby Creek, which reduced sediment contributions to the stream. Princeton Hydro provided construction observation and administration to ensure the implementation met the stakeholders’ expectations and design intent. This project was funded by the PADEP Growing Greener Grant program, the National Fish and Wildlife Foundation, and a NOAA settlement fund from the 2004 Athos I oil spill on the Delaware River. [post_title] => Kent Park Dam Removal [post_excerpt] => [post_status] => publish [comment_status] => closed [ping_status] => closed [post_password] => [post_name] => kent-park-dam-removal [to_ping] => [pinged] => [post_modified] => 2024-07-30 15:08:14 [post_modified_gmt] => 2024-07-30 15:08:14 [post_content_filtered] => [post_parent] => 0 [guid] => https://princetonhydro.com/?post_type=project&p=15487 [menu_order] => 0 [post_type] => project [post_mime_type] => [comment_count] => 0 [filter] => raw ) [2] => WP_Post Object ( [ID] => 15402 [post_author] => 1 [post_date] => 2024-06-17 13:09:17 [post_date_gmt] => 2024-06-17 13:09:17 [post_content] => The Long Pond Dam currently serves as a barrier to migratory fish along Whitford Brook, a tributary to the Mystic River. Whitford Brook has seen significant declines in fish populations, in part due to dams along the river corridor that prevent fish from accessing upstream spawning habitat. Diadromous fish, including Alewife, Blueback Herring, American Shad, American Eel, and Sea Lamprey rely on access to upstream spawning habitat to complete their life cycle. For Long Pond specifically, CT DEEP Fisheries estimated that fish passage restoration could provide an annual run of more than 250,000 alewives. In conjunction with other recent improvements along Whitford Brook, facilitating fish passage at this location would create a 6.6-mile stretch of connected river corridor from the confluence of Whitford Brook with the Mystic River upstream to the top of Lantern Hill Pond. A nature-like fishway was identified as the targeted means of providing fish passage by Save the Sound as the configuration of the outlet structure and embankment were well suited to that approach (relative to a technical fishway) and because dam removal was not considered a viable option due to the recreational and habitat (spawning) value of the impoundment. Princeton Hydro’s scope included: evaluation of existing data including past H&H studies and engineering evaluations/inspections of the dam; site investigations including geomorphic assessment and wetland delineation; topographic, utility, and boundary surveys; development of a concept design; H&H analysis; geotechnical investigations; fish passage design; development of an engineering package (plans, technical specifications, construction cost estimate) and applications for regulatory approvals; and finalization of design documents based on regulatory feedback. The primary challenge presented by this project was that the dam in its existing configuration was not in compliance with CT DEEP dam safety standards and that improvements/modifications to the dam to bring it into compliance were being handled by others. Further, site constraints dictated that installation of a nature-like fishway would require replacement of the dam’s outlet structure, which would increase the scope and complexity of the project beyond that originally envisioned. While Princeton Hydro’s design of the nature-like fishway is largely complete, construction can not move forward until finalized plans for bringing the dam into compliance are completed by others and integrated with the proposed fish passage design. Princeton Hydro continues to coordinate with Save the Sound and other project partners to assure that future site improvements will work seamlessly with the proposed fish passage improvements. [post_title] => Designing a Nature-like Fishway at Long Pond Dam [post_excerpt] => [post_status] => publish [comment_status] => closed [ping_status] => closed [post_password] => [post_name] => design-of-nature-like-fishway-at-long-pond-dam [to_ping] => [pinged] => [post_modified] => 2024-07-24 09:54:10 [post_modified_gmt] => 2024-07-24 09:54:10 [post_content_filtered] => [post_parent] => 0 [guid] => https://princetonhydro.com/?post_type=project&p=15402 [menu_order] => 0 [post_type] => project [post_mime_type] => [comment_count] => 0 [filter] => raw ) [3] => WP_Post Object ( [ID] => 14832 [post_author] => 1 [post_date] => 2024-04-18 15:06:24 [post_date_gmt] => 2024-04-18 15:06:24 [post_content] => Princeton Hydro was contracted by American Rivers to design, apply for permits, and provide construction administration services for the removal of the Kehm Run Dam, an earthen embankment, 270-feet long by 22 feet high, with a cast-in-place ogee spillway, about six (6) feet in height. The former impoundment was five (5) acres in size and contained an estimated 40,000 cubic yards of accumulated sediment. Princeton Hydro conducted a bathymetric survey, developed engineering plans, performed hydrologic and hydraulic analysis, applied to PADEP Dam Safety for a Restoration Waiver, and also to the York County Soil Conservation District plan approval. As part of the regulatory activities, Princeton Hydro subcontracted for a bog turtle (Glyptemys muhlenbergii) Phase I assessment, PA Historic and Museum Commission (PHMC) notices, and filed for a PA Fish and Boat Commission (PFBC) water lowering authorization. The dam was breached in 2019, and the project was completed the following year, with follow up site visits in 2021. [gallery link="none" size="medium" columns="2" ids="14830,14831"] The project was challenging due to the quantity of sediment encountered and its fine-grained nature as a colloidal (very small clay particles), with a relatively small stream immediately downstream. As a result of PADEP Dam Safety inspecting the site, expressing their concerns about the quantity of sediment, Princeton Hydro prepared a revised breach design that provided containment of the sediment, while deregulating the dam. As a result, the former lakebed created an opportunity for its use to as a nature-based BMP to address nutrient loading to the Susquehanna River and Chesapeake Bay. The Susquehanna River Basin Commission saw this opportunity and funded a next phase to further enhance the wetlands created to improve sediment capture from the watershed. This was a challenging project and has been documented by American Rivers in their blog as “Taking the Lemons and Making some Dam Lemonade”. As a project that provided significant lessons in adaptive management and making the most out of a challenging project. [caption id="attachment_14829" align="alignnone" width="1477"] Photo by American Rivers[/caption] [post_title] => Kehm Run Dam Removal Design [post_excerpt] => [post_status] => publish [comment_status] => closed [ping_status] => closed [post_password] => [post_name] => 14832 [to_ping] => [pinged] => [post_modified] => 2024-05-08 13:28:08 [post_modified_gmt] => 2024-05-08 13:28:08 [post_content_filtered] => [post_parent] => 0 [guid] => https://princetonhydro.com/?post_type=project&p=14832 [menu_order] => 0 [post_type] => project [post_mime_type] => [comment_count] => 0 [filter] => raw ) [4] => WP_Post Object ( [ID] => 14826 [post_author] => 1 [post_date] => 2024-04-18 14:55:52 [post_date_gmt] => 2024-04-18 14:55:52 [post_content] => Connecticut Fund for the Environment (FE) and Save the Sound (STS), in partnership with USFWS and CTDEEP Inland Fisheries Division, secured federal funding to remove the Hyde Pond Dam, restoring Whitford Brook, the primary in-flowing stream to the Mystic River estuary, to a natural free-flowing condition. This created unobstructed fish passage from Mystic River up through the project site, and removed a threat to public safety. The existing dam was an earthen embankment with a concrete capped masonry spillway 4.8 feet high that created a 12-acre impoundment. A fishway installed at the dam by CT DEEP to support a regionally-important river herring run and sea-run brook trout fishery was known to be ineffective due to its outlet location, beaver interference, and frequent low flows due to leakage through the dam. The dam removal restored fish passage to 4.1 miles of stream and provide access for alewife, blueback herring, American eel, American shad, and sea-run brook trout. [gallery link="none" size="medium" ids="14819,14821,14820"] Princeton Hydro confirmed through impoundment probing and bathymetric survey that the impoundment contained significant quantities of impounded sediments that had become densely vegetated as scrub-shrub vegetation. Sediment management and wetland impacts became driving factors in the project design and regulatory process. Princeton Hydro coordinated with CT DEEP Planning and Standards Division to develop and approve a sediment sampling plan that included multiple samples throughout the site as well as downstream and upstream. Results indicated some elevated contaminant levels in some areas. Princeton Hydro developed a sediment management plan and construction sequence, informed by the sediment analysis that balanced active sediment management and passive river restoration. The design entailed excavation of a portion of the sediment prone to mobilization that was then replaced, stabilized, and vegetated on-site. Princeton Hydro coordinated closely with CFE/STS to negotiate with US Army Corps of Engineers and CT DEEP regulatory divisions to minimize impacts to wetland resources as much as practicable, protect downstream water quality, restore river and riparian functions to the site, and stay within grant cost limits. RiverLogic Solutions provided construction services, and Princeton Hydro provided construction supervision to remove the dam within budget and on schedule in 2015. Since removal, the site has undergone a gradual transition in vegetation but remains a vibrant stream-floodplain wetland complex. [gallery link="none" ids="14824,14823,14825"] [post_title] => Hyde Pond Dam Removal [post_excerpt] => [post_status] => publish [comment_status] => closed [ping_status] => closed [post_password] => [post_name] => hyde-pond-dam-removal [to_ping] => [pinged] => [post_modified] => 2024-04-18 15:07:19 [post_modified_gmt] => 2024-04-18 15:07:19 [post_content_filtered] => [post_parent] => 0 [guid] => https://princetonhydro.com/?post_type=project&p=14826 [menu_order] => 0 [post_type] => project [post_mime_type] => [comment_count] => 0 [filter] => raw ) [5] => WP_Post Object ( [ID] => 14586 [post_author] => 1 [post_date] => 2024-02-06 20:58:15 [post_date_gmt] => 2024-02-06 20:58:15 [post_content] => Princeton Hydro was hired by the Town of Scituate and MA Division of Ecological Restoration to provide engineering feasibility, design, permitting, and construction oversight services for the dam removal in Scituate, MA. The project was a MA DER priority project due to its high potential for restoration of diadromous fish. The dam was a head of tide dam with rainbow smelt spawning habitat just below the dam. The site had significant historic value, including an old mill building once owned by the great, great, great grandfather of Abraham Lincoln. The site was also bifurcated by the historic “Boundary Line,” a border established in 1640 which denoted the boundary between the colonies of Massachusetts and New Plymouth. Significant Section 106 historic and archeological consultation was therefore incorporated into this dam removal project. The project also included significant outreach to the local community, primarily made up of abutting property owners concerned about the loss of the impoundment behind the dam. [gallery link="none" columns="2" ids="14588,14590"] The project was initiated due to the need to pave Mordechai Lincoln Road, but paving was not possible without first repairing the dam’s overflow pipe which extended under the historic mill building. A project partnership was then developed with numerous state agencies and environmental organizations, led by MA DER and the Town of Scituate, to find funding for the removal of the dam and the restoration of Bound Brook. The dam removal was complicated by the existence of an active water main directly upstream of the dam. As part of the design, our design team had to relocate the water main as well as slip line the decaying pipe under the historic mill building. Passive restoration methods were utilized, allowing Bound Brook to find its own diverse channel pattern within the dewatered impoundment. The design plans depicted multiple potential paths where the channel might form. At Princeton Hydro we practice a “less is more” design approach to restoration, placing our faith in the natural channel forming processes of a river whenever possible. [post_title] => Hunters Pond Dam Removal [post_excerpt] => [post_status] => publish [comment_status] => closed [ping_status] => closed [post_password] => [post_name] => hunters-pond-dam-removal-2 [to_ping] => [pinged] => [post_modified] => 2024-03-06 21:05:29 [post_modified_gmt] => 2024-03-06 21:05:29 [post_content_filtered] => [post_parent] => 0 [guid] => https://princetonhydro.com/?post_type=project&p=14586 [menu_order] => 0 [post_type] => project [post_mime_type] => [comment_count] => 0 [filter] => raw ) [6] => WP_Post Object ( [ID] => 14093 [post_author] => 1 [post_date] => 2023-12-13 11:31:44 [post_date_gmt] => 2023-12-13 11:31:44 [post_content] => The Collins Company Lower Dam, constructed in 1910 as a hydroelectric dam, is located on the Farmington River, approximately 1 mile downstream (south) of the Collinsville Dam and State Route 179, in Avon, Connecticut, south of the Collinsville Town border and across the Farmington River from the Town of Burlington. In 2011, a pre-feasibility study was completed on the Collinsville Dam and the Collins Company Lower Dam to determine whether these defunct hydroelectric dams could be repowered. The study found that repowering only one of the dams was economically feasible. [caption id="attachment_13849" align="aligncenter" width="718"] Collins Company Lower Dam prior to removal. Photo by CT Insider.[/caption] In 2019, Canton Hydro, LLC began the retrofit of the Collinsville Dam for hydroelectric generation in conjunction with the construction of a fishway in order to allow passage of anadromous fish (i.e., American Shad, Alewife, Blueback Herring, and Sea Lamprey) to the upstream reaches of the Farmington River. Removal of the Collins Company Lower Dam will allow passage to the base of the newly retrofitted Collinsville Dam. The goals of this project are to eliminate a barrier to migratory fish; eliminate an obsolete dam; remove a public safety risk; re-create a free flowing, ecologically productive, and natural river channel; and create stable and safe public access. Also as noted above, this dam removal is imperative to enable fish passage at the fishway under construction at the Collinsville Dam, approximately one mile upstream. As part of the dam removal design process, Princeton Hydro developed a Sediment Management Plan, which involved assessing impounded sediment quality and quantity by conducting bathymetric mapping to sense elevation of top and bottom of unconsolidated sediment, and sampling and analyzing sediment for a broad range of contaminants. In addition to using the information gathered through the assessment, a professional survey and geomorphic concepts were used to determine the volume of impounded sediment and the anticipated river profile following dam removal. Princeton Hydro completed the bathymetric surveys, hydrologic and hydraulic analysis, geotechnical engineering, construction phasing determination, demolition and blasting plans, preparation of 30%, 60%, 90% and 100% designs, and regulatory review applications. Princeton Hydro is currently working through the engineering designs and permit applications. [post_title] => Collins Company Lower Dam Removal [post_excerpt] => [post_status] => publish [comment_status] => closed [ping_status] => closed [post_password] => [post_name] => collins-company-lower-dam-removal [to_ping] => [pinged] => [post_modified] => 2023-12-13 11:31:44 [post_modified_gmt] => 2023-12-13 11:31:44 [post_content_filtered] => [post_parent] => 0 [guid] => https://princetonhydro.com/?post_type=project&p=14093 [menu_order] => 0 [post_type] => project [post_mime_type] => [comment_count] => 0 [filter] => raw ) [7] => WP_Post Object ( [ID] => 13638 [post_author] => 1 [post_date] => 2023-08-16 11:00:04 [post_date_gmt] => 2023-08-16 11:00:04 [post_content] => Princeton Hydro has partnered with Wildlands Conservancy for over a decade on multiple dam removals in the Lehigh River Valley. Our firm designed and permitted the removal of eight consecutive barriers on Jordan Creek, including three consecutive low-head dams. We also designed and permitted two low-head dams on Little Lehigh Creek. Collectively, these dam removal projects reconnected miles of river, enhanced aquatic habitat, and improved adjacent parkland and recreational fishing in the economically-stressed, urban communities of Allentown, PA. Building upon the successes of the barrier removals on Jordan and Little Lehigh Creeks, Princeton Hydro partnered with the Wildlands Conservancy again in 2018 to remove a combination of four privately and publicly owned dams; three of which were consecutive on Bushkill Creek in Easton, PA. The dam removal projects served as a model for landowners and municipalities regarding the need for future dam removals throughout the Delaware and Lehigh Valley Watersheds. [gallery columns="2" link="none" ids="12046,12053"] Combined, the barrier removals were part of a larger, watershed-wide effort to improve aquatic connectivity, fisheries, and benthic macro-invertebrate and wildlife habitats. The projects restored fish passage, reduced nonpoint source pollution, improved water quality, and restored capacity for groundwater recharge, as well as stabilized and restored the stream’s channels and banks. As part of the barrier removal projects, Princeton Hydro:
The Martin Dam was constructed on an active farm in 1961 as part of USDA’s sustainable farms pond construction initiative. Martin Dam’s robust 4,000 cubic yards of placed dam material resulted in the impoundment of only 3.5 acres of surface water. Several years ago, during the removal of a beaver dam that was obstructing the dam outlet, the riser structure was inadvertently destroyed, and a large part of the earthen dam collapsed. Due to the damage, the dam was put under an enforcement action from the Maryland Department of the Environment (MDE) Dam Safety Program. Site investigations showed an outlet culvert in total disrepair and severe erosion of the dam and downstream areas.
Fearing the risk to property and life from a catastrophic dam failure, GreenTrust Alliance, in partnership with Princeton Hydro, were enlisted to design, develop, and enact an emergency dam breach. The earthen dam was approximately 20 feet in height and 490 feet in length, with an impoundment of approximately 3.48 acres. The contributing drainage area was approximately 0.25 square miles (160 acres) of low density residential land use and the primary inflowing channel, Overshot Branch, was intermittent or ephemeral. The assessment and design involved probing within the impoundment, which revealed water depths averaging 4.7 feet, with a maximum of 7.5 feet, and impounded sediment depths averaging 1.0 foot, with a maximum of 3.0 feet.
Princeton Hydro prepared a 35% design plan for the earthen dam removal, and this plan was subsequently approved by MDE Dam Safety with an emergency permit, forgoing the typical months-long design and review process. The dam breach was implemented in late 2018.
After the dam breach, Princeton Hydro completed a hydrologic and hydraulic assessment. Pre- and post-breach conditions were modeled to determine the potential increase in flood elevations to downstream properties. In addition, a dam failure was also modeled to assess the potential risks should the dam have failed. In comparing the pre-and post-breach scenarios, 100-year flood elevations increased between 0.01 and 0.29 feet for approximately 1 mile downstream of the pond. The floodplain valley for this stream was relatively narrow which means any increases in discharge translated to larger increases on peak flood elevations compared to the total width of the floodplain. However, the narrow floodplain also acted a barrier, ensuring that flooding was mostly contained to the area around the stream itself. No additional structures were inundated as a result of the breach.
Princeton Hydro, along with GreenVest and Green Trust Alliance, developed a design that enhanced in-stream habitat of the downstream reach, and allowed for passive wetland conversion and restoration of the former impoundment.
Princeton Hydro was contracted to investigate, analyze, and design the removal of obstructions and restore natural stream function on Darby Creek. With funding from the National Fish and Wildlife Foundation and Pennsylvania Growing Greener program, the objective of the project was to remove remnant bridge piers in Colwyn and Sharon Hill Boroughs, a failed dam in Darby Borough, a mill dam in Landsdowne and Clifton Heights Boroughs, and a dam in Upper Darby Township and Clifton Heights Borough.
The Kent Park Dam was a placed rock structure that spanned Darby Creek within Kent Park within Delaware County. Princeton Hydro prepared hydrologic and hydraulic analyses; assessed fluvial geomorphic characteristics; determined infrastructure impacts; inventoried natural resources, including wetland delineations and invasive species; and assessed impounded sediment. Design plan sets were prepared, public presentations completed, and permit applications submitted to the Pennsylvania Department of Environmental Protection, U.S. Army Corps of Engineers, and the Delaware County Soil Conservation District.
This project included the reconstruction of the stream bank using bioengineered soil lifts; the innovative construction of a riffle over a sanitary sewer line, which protruded above the stream bed; and the creation of a wetland complex within a small spring tributary to Darby Creek, which reduced sediment contributions to the stream.
Princeton Hydro provided construction observation and administration to ensure the implementation met the stakeholders’ expectations and design intent. This project was funded by the PADEP Growing Greener Grant program, the National Fish and Wildlife Foundation, and a NOAA settlement fund from the 2004 Athos I oil spill on the Delaware River.
The Long Pond Dam currently serves as a barrier to migratory fish along Whitford Brook, a tributary to the Mystic River. Whitford Brook has seen significant declines in fish populations, in part due to dams along the river corridor that prevent fish from accessing upstream spawning habitat. Diadromous fish, including Alewife, Blueback Herring, American Shad, American Eel, and Sea Lamprey rely on access to upstream spawning habitat to complete their life cycle. For Long Pond specifically, CT DEEP Fisheries estimated that fish passage restoration could provide an annual run of more than 250,000 alewives. In conjunction with other recent improvements along Whitford Brook, facilitating fish passage at this location would create a 6.6-mile stretch of connected river corridor from the confluence of Whitford Brook with the Mystic River upstream to the top of Lantern Hill Pond.
A nature-like fishway was identified as the targeted means of providing fish passage by Save the Sound as the configuration of the outlet structure and embankment were well suited to that approach (relative to a technical fishway) and because dam removal was not considered a viable option due to the recreational and habitat (spawning) value of the impoundment.
Princeton Hydro’s scope included: evaluation of existing data including past H&H studies and engineering evaluations/inspections of the dam; site investigations including geomorphic assessment and wetland delineation; topographic, utility, and boundary surveys; development of a concept design; H&H analysis; geotechnical investigations; fish passage design; development of an engineering package (plans, technical specifications, construction cost estimate) and applications for regulatory approvals; and finalization of design documents based on regulatory feedback.
The primary challenge presented by this project was that the dam in its existing configuration was not in compliance with CT DEEP dam safety standards and that improvements/modifications to the dam to bring it into compliance were being handled by others. Further, site constraints dictated that installation of a nature-like fishway would require replacement of the dam’s outlet structure, which would increase the scope and complexity of the project beyond that originally envisioned.
While Princeton Hydro’s design of the nature-like fishway is largely complete, construction can not move forward until finalized plans for bringing the dam into compliance are completed by others and integrated with the proposed fish passage design. Princeton Hydro continues to coordinate with Save the Sound and other project partners to assure that future site improvements will work seamlessly with the proposed fish passage improvements.
Princeton Hydro was contracted by American Rivers to design, apply for permits, and provide construction administration services for the removal of the Kehm Run Dam, an earthen embankment, 270-feet long by 22 feet high, with a cast-in-place ogee spillway, about six (6) feet in height. The former impoundment was five (5) acres in size and contained an estimated 40,000 cubic yards of accumulated sediment. Princeton Hydro conducted a bathymetric survey, developed engineering plans, performed hydrologic and hydraulic analysis, applied to PADEP Dam Safety for a Restoration Waiver, and also to the York County Soil Conservation District plan approval. As part of the regulatory activities, Princeton Hydro subcontracted for a bog turtle (Glyptemys muhlenbergii) Phase I assessment, PA Historic and Museum Commission (PHMC) notices, and filed for a PA Fish and Boat Commission (PFBC) water lowering authorization. The dam was breached in 2019, and the project was completed the following year, with follow up site visits in 2021.
The project was challenging due to the quantity of sediment encountered and its fine-grained nature as a colloidal (very small clay particles), with a relatively small stream immediately downstream. As a result of PADEP Dam Safety inspecting the site, expressing their concerns about the quantity of sediment, Princeton Hydro prepared a revised breach design that provided containment of the sediment, while deregulating the dam. As a result, the former lakebed created an opportunity for its use to as a nature-based BMP to address nutrient loading to the Susquehanna River and Chesapeake Bay. The Susquehanna River Basin Commission saw this opportunity and funded a next phase to further enhance the wetlands created to improve sediment capture from the watershed.
This was a challenging project and has been documented by American Rivers in their blog as “Taking the Lemons and Making some Dam Lemonade”. As a project that provided significant lessons in adaptive management and making the most out of a challenging project.
Connecticut Fund for the Environment (FE) and Save the Sound (STS), in partnership with USFWS and CTDEEP Inland Fisheries Division, secured federal funding to remove the Hyde Pond Dam, restoring Whitford Brook, the primary in-flowing stream to the Mystic River estuary, to a natural free-flowing condition. This created unobstructed fish passage from Mystic River up through the project site, and removed a threat to public safety. The existing dam was an earthen embankment with a concrete capped masonry spillway 4.8 feet high that created a 12-acre impoundment. A fishway installed at the dam by CT DEEP to support a regionally-important river herring run and sea-run brook trout fishery was known to be ineffective due to its outlet location, beaver interference, and frequent low flows due to leakage through the dam. The dam removal restored fish passage to 4.1 miles of stream and provide access for alewife, blueback herring, American eel, American shad, and sea-run brook trout.
Princeton Hydro confirmed through impoundment probing and bathymetric survey that the impoundment contained significant quantities of impounded sediments that had become densely vegetated as scrub-shrub vegetation. Sediment management and wetland impacts became driving factors in the project design and regulatory process. Princeton Hydro coordinated with CT DEEP Planning and Standards Division to develop and approve a sediment sampling plan that included multiple samples throughout the site as well as downstream and upstream.
Results indicated some elevated contaminant levels in some areas. Princeton Hydro developed a sediment management plan and construction sequence, informed by the sediment analysis that balanced active sediment management and passive river restoration. The design entailed excavation of a portion of the sediment prone to mobilization that was then replaced, stabilized, and vegetated on-site.
Princeton Hydro coordinated closely with CFE/STS to negotiate with US Army Corps of Engineers and CT DEEP regulatory divisions to minimize impacts to wetland resources as much as practicable, protect downstream water quality, restore river and riparian functions to the site, and stay within grant cost limits. RiverLogic Solutions provided construction services, and Princeton Hydro provided construction supervision to remove the dam within budget and on schedule in 2015. Since removal, the site has undergone a gradual transition in vegetation but remains a vibrant stream-floodplain wetland complex.
Princeton Hydro was hired by the Town of Scituate and MA Division of Ecological Restoration to provide engineering feasibility, design, permitting, and construction oversight services for the dam removal in Scituate, MA. The project was a MA DER priority project due to its high potential for restoration of diadromous fish. The dam was a head of tide dam with rainbow smelt spawning habitat just below the dam. The site had significant historic value, including an old mill building once owned by the great, great, great grandfather of Abraham Lincoln. The site was also bifurcated by the historic “Boundary Line,” a border established in 1640 which denoted the boundary between the colonies of Massachusetts and New Plymouth. Significant Section 106 historic and archeological consultation was therefore incorporated into this dam removal project. The project also included significant outreach to the local community, primarily made up of abutting property owners concerned about the loss of the impoundment behind the dam.
The project was initiated due to the need to pave Mordechai Lincoln Road, but paving was not possible without first repairing the dam’s overflow pipe which extended under the historic mill building. A project partnership was then developed with numerous state agencies and environmental organizations, led by MA DER and the Town of Scituate, to find funding for the removal of the dam and the restoration of Bound Brook.
The dam removal was complicated by the existence of an active water main directly upstream of the dam. As part of the design, our design team had to relocate the water main as well as slip line the decaying pipe under the historic mill building. Passive restoration methods were utilized, allowing Bound Brook to find its own diverse channel pattern within the dewatered impoundment.
The design plans depicted multiple potential paths where the channel might form. At Princeton Hydro we practice a “less is more” design approach to restoration, placing our faith in the natural channel forming processes of a river whenever possible.
The Collins Company Lower Dam, constructed in 1910 as a hydroelectric dam, is located on the Farmington River, approximately 1 mile downstream (south) of the Collinsville Dam and State Route 179, in Avon, Connecticut, south of the Collinsville Town border and across the Farmington River from the Town of Burlington. In 2011, a pre-feasibility study was completed on the Collinsville Dam and the Collins Company Lower Dam to determine whether these defunct hydroelectric dams could be repowered. The study found that repowering only one of the dams was economically feasible.
In 2019, Canton Hydro, LLC began the retrofit of the Collinsville Dam for hydroelectric generation in conjunction with the construction of a fishway in order to allow passage of anadromous fish (i.e., American Shad, Alewife, Blueback Herring, and Sea Lamprey) to the upstream reaches of the Farmington River. Removal of the Collins Company Lower Dam will allow passage to the base of the newly retrofitted Collinsville Dam.
The goals of this project are to eliminate a barrier to migratory fish; eliminate an obsolete dam; remove a public safety risk; re-create a free flowing, ecologically productive, and natural river channel; and create stable and safe public access. Also as noted above, this dam removal is imperative to enable fish passage at the fishway under construction at the Collinsville Dam, approximately one mile upstream.
As part of the dam removal design process, Princeton Hydro developed a Sediment Management Plan, which involved assessing impounded sediment quality and quantity by conducting bathymetric mapping to sense elevation of top and bottom of unconsolidated sediment, and sampling and analyzing sediment for a broad range of contaminants. In addition to using the information gathered through the assessment, a professional survey and geomorphic concepts were used to determine the volume of impounded sediment and the anticipated river profile following dam removal.
Princeton Hydro completed the bathymetric surveys, hydrologic and hydraulic analysis, geotechnical engineering, construction phasing determination, demolition and blasting plans, preparation of 30%, 60%, 90% and 100% designs, and regulatory review applications.
Princeton Hydro is currently working through the engineering designs and permit applications.
Princeton Hydro has partnered with Wildlands Conservancy for over a decade on multiple dam removals in the Lehigh River Valley. Our firm designed and permitted the removal of eight consecutive barriers on Jordan Creek, including three consecutive low-head dams. We also designed and permitted two low-head dams on Little Lehigh Creek. Collectively, these dam removal projects reconnected miles of river, enhanced aquatic habitat, and improved adjacent parkland and recreational fishing in the economically-stressed, urban communities of Allentown, PA.
Building upon the successes of the barrier removals on Jordan and Little Lehigh Creeks, Princeton Hydro partnered with the Wildlands Conservancy again in 2018 to remove a combination of four privately and publicly owned dams; three of which were consecutive on Bushkill Creek in Easton, PA. The dam removal projects served as a model for landowners and municipalities regarding the need for future dam removals throughout the Delaware and Lehigh Valley Watersheds.
Combined, the barrier removals were part of a larger, watershed-wide effort to improve aquatic connectivity, fisheries, and benthic macro-invertebrate and wildlife habitats. The projects restored fish passage, reduced nonpoint source pollution, improved water quality, and restored capacity for groundwater recharge, as well as stabilized and restored the stream’s channels and banks.
As part of the barrier removal projects, Princeton Hydro:
Princeton Hydro was contracted by American Rivers to complete the design and permitting phases, as well as construction oversight, for the removal of the Downing Ridge Dam and associated restoration of the East Branch Brandywine Creek. The Downing Ridge Dam (aka Brandywine Dam) was located on East Branch Brandywine Creek in Caln and East Caln Townships in Chester County, PA approximately 0.25 miles upstream of where U.S. 30 (Coatesville Downingtown Bypass) crosses over East Branch Brandywine Creek. The dam was a 5.25-foot high, 182-foot long concrete structure constructed in 1917 to provide water for two paper mills owned by the S. Austin Bicking Paper Manufacturing Company. Based on information presented in the original plan map for the dam dated June 20, 1917, the concrete dam replaced an existing dam at the site.
Project elements led by Princeton Hydro included: data review; site investigation and geomorphic assessment; sediment sampling and characterization; resource delineation; hydrology and hydraulics analysis; engineering and restoration design; permit application submission and regulatory approval; meetings and public outreach; construction oversight; and as-built survey and dam removal certification.
The Downing Ridge Dam Removal Project involved complete removal of the 182-foot long concrete dam and the 44-foot long concrete abutment wall located on the west stream bank. The concrete abutment wall on the east stream bank remained to buttress the stream bank and protect the head of the mill race.
The Marshfield 8 Dam is a historic run-of-the-river dam located on the Winooski River. The Vermont Agency of Natural Resources (VT ANR), acting on behalf of the private owner who was concerned with its deteriorating condition, contracted Princeton Hydro to complete sediment management planning, engineering design, and permitting for the removal of the dam.
Princeton Hydro conducted a detailed site investigation, sediment probing, and hydraulic modeling to develop a site-specific sediment management plan and engineering design. The plan utilized field data, and hydrologic and hydraulic modeling to address the geomorphic response of the existing impounded reach and consequences of downstream sediment transport. In addition, Princeton Hydro proposed long-term monitoring measures to assess geomorphic changes and to inform future dam removal designs led by the VT ANR.
During the planning process, Princeton Hydro coordinated with a historic preservation firm to research and document historic uses of the site. In developing the design, Princeton Hydro coordinated with the adjacent landowner to design bank stabilization measures that incorporated the landowner’s concerns, as well anticipated shear stresses and channel adjustment post-removal. Princeton Hydro also performed construction oversight during the implementation of this project.
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