Hydropower

Commonwealth-Owned Dams Statewide Hydroelectric Power Potential Assessment

gzadan — Fri, 08 Jul 2022 20:13:15 +0000

Commonwealth-Owned Dams Statewide Hydroelectric Power Potential Assessment gzadan Fri, 07/08/2022 - 16:13

Challenge

The Commonwealth of Massachusetts Department of Conservation and Recreation (DCR) owns and manages more than 350 dams. The DCR recognized that the potential for hydroelectric generation at these dams might provide additional value in the form of potential revenue for the DCR and Commonwealth, greenhouse gas (GHG) emissions reductions, and sustainable power for Commonwealth communities.

Solution

GZA was engaged by the DCR to perform a screening-level assessment of hydropower generation potential at each of its dams. This assessment was meant to be used as an initial evaluation tool to identify those dams where a significant amount of hydropower potential exists and thereby focus on the dams where development might be most viable.

GZA utilized information contained in the DCR’s dam safety database, as well as the National Inventory of Dams, and GZA’s own extensive knowledge of the dams of Massachusetts, to develop information regarding the physical characteristics at each dam pertinent to hydropower generation. GZA then accessed USGS historic streamflow gage data to create proxy flow duration curves at each of the dam sites. Based on this data, GZA estimated the power (kW) and average annual energy (kWh) production potential at each of the dams in the DCR’s inventory. GZA identified those dams where further investigation of hydropower generation presently made sense, and those which might be examined in the future.

Benefit

Based on the screening analysis, GZA is assisting DCR with more detailed evaluations of hydropower potential at certain dams and with preparing applications for FERC preliminary permits for 20 of the dams. Generation of hydropower at DCR dams could be a source of revenue for the state and an example of good environmental stewardship.

Utilized existing publicly-available data to perform a screening level assessment of the hydroelectric generation potential of hundreds of dams
Identified dozens of dams where hydroelectric development could be both technically and economically feasible

Energy

Dams, Levees, and Hydropower

Ituango Hydroelectric Dam Geotechnical Instrumentation Audit

gzadan — Fri, 24 Jun 2022 19:52:49 +0000

Ituango Hydroelectric Dam Geotechnical Instrumentation Audit gzadan Fri, 06/24/2022 - 15:52

Construction of the 2,400-megawatt Ituango Hydroelectric Dam began in 2010 to significantly expand Colombia’s electrical generation capacity. A diversion tunnel collapse in 2018, during construction, required flooding of the unfinished powerhouse and accelerated dam construction to ensure the safety of the downstream population. As a result of the collapse and subsequent re-insurance requirements, the dam owner/operator sought GZA’s expertise to audit the existing instrumentation and monitoring system and make recommendations for improvement.

Challenge

This massive infrastructure project had produced millions of data points to be reviewed. The duration of the construction and the predominantly manual data collection and monitoring methods further complicated the audit process. After the 2018 collapse, the design team replaced many instruments with alternate manufactures; instruments continue to be added on weak rock slopes and within the underground structures.

Solution

Prior to a five-day visit to the site, GZA’s team reviewed all available as-built and monitoring data. During the site visit, GZA met with individual project teams, toured all aspects of the site, and observed installation, data collection and processing procedures first-hand. Key issues identified included serviceability of instruments, such as installation technique, sensor type, and monitoring method; management and communication of data findings; alert response timing; and refinement of data calculation and processing.

Benefit

Because of GZA’s experience in geotechnical instrumentation design, installation, and implementation as well as dam engineering design and construction the firm was well-positioned to conduct the audit of this extraordinary project. GZA’s comprehensive audit report is designed to benefit the project team and increase the effectiveness of the overall instrumentation program.

2,400-megawatt earth filled dam
Instrumentation audit prompted by tunnel collapse during construction
Completed on-site visit
Reviewed vast amounts of data, over 3,000 instrumentation points
Recommended improvements in operation, data quality, monitoring responsiveness

Dams, Levees, and Hydropower

Emergency Action Plan Updates and Dam Break Modeling for Great River Hydropower Dams

gzadan — ��Ϸ��d, 11 May 2022 19:07:46 +0000

Emergency Action Plan Updates and Dam Break Modeling for Great River Hydropower Dams gzadan ��Ϸ��d, 05/11/2022 - 15:07

Challenge

Great River Hydro is the owner and operator of 16 dams in New England (13 for hydropower, 3 for storage). TransCanada, the former owner, engaged GZA to perform dam break analyses, hazard classification assessments, spillway capacity analyses, and Emergency Action Plan (EAP) updates for their dams.

Solution

GZA conducted dam break analyses for 6 of the dams. The dam breaks were used to develop updated inundation maps for the EAPs. For 4 dams, the dam break analyses were also used to evaluate the hazard classification and Inflow Design Flood (IDF). GZA performed the dam break analyses with a 1-D unsteady flow model using HEC-RAS version 5.0.1. GZA used the mapper feature in HEC-RAS to map the results after breach runs were simulated.

Additionally, for one dam, GZA used a HEC-RAS 2-D unsteady flow model to evaluate the capacity of the dam’s spillway discharge channel. The downstream channel opens into an unconfined terrain with no channel path, and for this reason, the analysis was performed as two dimensional. The model was used to evaluate if tailwater in the discharge channel causes submergence at the spillway.

The majority of the EAP updates involved reformatting the EAPs to conform with updates in the FERC Engineering Guidelines for the Evaluation of Hydropower Projects. The FERC guidelines were revised in 2015 to conform with the FEMA Publication No. P-64 �� Federal Guidelines for Emergency Action Planning for Dams.

Benefit

GZA was also contracted to develop an interactive web-based application that presents the inundation maps and data for Great River Hydro’s High Hazard dams. The web-based application, the GZA GeoTool ©, displays data, documents and imagery that is hosted on GZA’s Enterprise Portal and allow the user to easily and securely view the various features of an inundation map.

FERC-regulated dams
Emergency Action Plans
Dam breach analysis for, in total, 273 miles of river
Hazard Classification
Inflow Design Flood
Inundation mapping
Interactive Story Map highlighting each dam and associated EAP Information
Dams EAP Viewer ��Ϸ��b GIS application

Energy

Dams, Levees, and Hydropower

Byron ��Ϸ��ston Mill Dam No. 2 Hydroelectric Project

gzadan — ��Ϸ��d, 16 Oct 2019 17:18:00 +0000

Byron ��Ϸ��ston Mill Dam No. 2 Hydroelectric Project gzadan ��Ϸ��d, 10/16/2019 - 13:18

Challenge

GZA was engaged to assess the feasibility of upgrading two existing dams on the East Branch of the Housatonic River for hydroelectric generation. Originally built to provide water and hydromechanical power to paper mills adjacent to the river, the dams no longer generated energy. GZA’s work was integral to the client’s multi-phased approach to plan, design, and license the project while obtaining substantial financial assistance through sustainable energy grants.

Solution

GZA’s initial resource assessment study supported the client’s successful application to the Massachusetts Technology Collaborative (MTC) [now Mass Clean Energy Center] for a Feasibility Grant that considered hydropower generation at Byron ��Ϸ��ston Mill Dam No. 1 and Dam No. 2. GZA then prepared a full Feasibility Study investigating hydropower generation potential based on available head, available flow, and physical configuration of the facilities; technical and financial assessment of hydropower generation; and potential environmental and regulatory considerations. GZA also created a concept-level design for the preferred hydropower alternative which, based on the Feasibility Study results, was installation of a new hydropower generation plant at Byron ��Ϸ��ston Dam No. 2. GZA then assisted the client secure a MTC Design and Construction Grant, prepared FERC licensing documents, conducted stakeholder meetings, and helped develop a water quality study plan resulting from agency consultation comments. GZA prepared a draft and final exemption application for the project, as well as all final design plans, specifications, and contract documents. Design elements included interior structural work, penstock transition piece, and tailrace bulkhead, as well as the selection of a new 250 kW double regulated Kaplan turbine generator set.

Benefit

GZA's technical support, from pre-feasibility through licensing and contract documents, was integral to the funding and commissioning of this energy project.

Insights

250 kW small hydropower project
Hydrology/hydraulics, structural engineering, and civil engineering
MTC feasibility, design, and construction grants
FERC exemption from licensing
Federal, state, and local permits
Public outreach
Construction oversight assistance

Massachusetts

Energy

Water

Dams, Levees, and Hydropower

Site / Civil Engineering & Design

Hydroelectric Project- Confidential Client

Anonymous — Thu, 26 Sep 2019 13:56:43 +0000

Hydroelectric Project- Confidential Client Anonymous Thu, 09/26/2019 - 09:56

Challenge

A turbine extension and modernization program at this Pumped Storage Hydrogeneration Project required complete un-watering of the subsurface water conveyance structures that connect its Lower Reservoir (LR) and Upper Reservoir (UR). Stability of the earthfill embankment components of the project, which are sensitive to water surface elevations and changes in piezometric pressures, added complexity to the engineering process.

Solution

The operational water levels vary over a head differential of 50 feet for the UR and 40 feet for the LR. The structures consist of an 1,143-foot-deep concrete vertical shaft and horizontal power tunnel, which separates into four steel-lined 12-foot-diameter penstocks through a manifold structure located halfway from UR to LR.

The un-watering was carefully sequenced to lower the UR slightly below operational level; construct a temporary cofferdam at the UR; lower the UR an additional 30 feet; construct a permanent cofferdam; de-water the vertical shaft; and, finally, pump out the power tunnel, manifold and penstocks.

Water control for the project required extended periods of high water in the LR and a relatively rapid drawdown of the UR. Since both the Lower Dam and Upper Dike are zoned earthfill embankments, GZA reviewed their stability under the conditions and loading anticipated during the water control procedures and determined that there were adequate factors of safety at both structures. GZA was also asked to review the client’s cofferdam design, used to isolate the power shaft intake at the UR from the main body of the reservoir, which was left partially full. GZA subsequently inspected the cofferdam in the field post-construction.

Benefit

GZA executed the complex engineering evaluation and review calculation in support of this important modernization project, including ensuring the proposed project would not be detrimental to the stability of the facility’s most sensitive components.

Insights

Performed stability analyses for Lower Dam embankment and Upper Dike embankment
Performed stability analyses and design of temporary access road berm within Upper Reservoir
Reviewed design of cofferdam including rock sockets and inspected structure after completion
Presented results to Board of Consultants
Designed construction-phase water control system requirements to maintain the Upper Reservoir level below the top of cofferdam elevation and handle inflow from runoff, direct rainfall, and leakage.

Energy

Water

Dams, Levees, and Hydropower

Hydropower

Commonwealth-Owned Dams Statewide Hydroelectric Power Potential Assessment

Challenge

Solution

Benefit

Ituango Hydroelectric Dam Geotechnical Instrumentation Audit

Challenge

Solution

Benefit

Emergency Action Plan Updates and Dam Break Modeling for Great River Hydropower Dams

Challenge

Solution

Benefit

Byron ������Ϸ����ston Mill Dam No. 2 Hydroelectric Project

Challenge

Solution

Benefit

Hydroelectric Project- Confidential Client

Challenge

Solution

Benefit

Byron ��Ϸ��ston Mill Dam No. 2 Hydroelectric Project