Van Der Tak, Laurens, Van Der Tak

Van Der Tak, Laurens

Laurens is Jacobs Water Resilience Director for the Americas. He is a water resources engineer with more than 33 years of experience addressing stormwater and water resource issues, including climate vulnerability assessments and adaptation, green infrastructure, flood modeling, stormwater utilities, and water/wastewater master planning. He is Chair of AWWAs Water Resources Sustainability Division.

Titles from this speaker

Description: Arlington County's Flood Risk Assessment Management Plan: A Blueprint For Living...

Arlington County's Flood Risk Assessment Management Plan: A Blueprint For Living With Water In A Changing Climate

Abstract

Introduction
Arlington County, Virginia, is developing a Stormwater Program Risk Assessment Management Plan (RAMP). The paper and presentation will summarize how the RAMP team conducted flood modeling and risk assessment considering climate change for urban interior flooding, riverine flooding and coastal flooding. The RAMP flood implementation strategy will inform and prioritize strategic investments for mitigating risk, based on economic, environmental and social equity criteria and quantified project benefits and co-benefits with a measurable return-on-investment methodology. The presentation will illustrate modeling visualization tools used to communicate and analyze risk and consequential impacts in support of a long-term resilience strategy.
Methodology
The RAMP project includes the following key tasks: data collection; climate projections and scenario development; Interior and riverine flood modeling using Flood Modeller FAST, PCSWMM, and HEC-RAS; coastal storm surge modeling using MIKE 21; vulnerability assessments; risk assessments; mitigation alternatives analysis; project prioritization; and support for public outreach and grant writing.
The flood modeling was conducted based on both current conditions and projected future conditions in 2040 and 2070, with changes in rainfall intensity-duration-frequency (IDF) and sea level rise. Jacobs developed the IDF projections using SimCLIM, which collates the latest global climate model data. Sea level rise projections were compiled from the most recent projections available from NOAA for the Chesapeake Bay and Washington DC (see Figure 1). The interior flood modeling was conducted in two steps, with initial screening of 2D overland flow for extreme events with FAST without the pipe network. These modeling results, coupled with historical flood complaint records, were used to select priority watersheds for detailed 1D/2D modeling with PCSWMM of storm drain pipes and surface overland flow, which is necessary to identify overland flow paths and facilities at risk of flood damage and repetitive losses. Refinement of 2D model extents and modeling approach allows for efficient 2D hydraulic modeling, with a balance between model resolution and runtime (see Figure 2). â€ƒ
Preliminary Results
The flood modeling results were used to conduct a qualitative vulnerability assessment to determine which critical facilities (including public and private utilities), vulnerable groups and environmental resources are most at risk, based on current and projected flooding (see Figure 3).
The watersheds with the highest number of vulnerable areas, assets and resources will then be selected for detailed risk assessments using HAZUS and also site-by-site assessments of selected public facilities to assess individual assets at risk based on projected depth of flooding. To facilitate analysis and communication of results, the Jacobs team developed a GIS viewer tool for all the flood modeling results to assist in model validation and subsequent analysis of vulnerability, risk and alternatives. The RAMP analysis will inform the prioritization of strategic investments and policy guidelines for mitigating flood risk under current and future climate conditions. Work on the plan is ongoing and should be complete by April 2022.

Arlington County, Virginia, is developing a Stormwater Program Risk Assessment Management Plan (RAMP). The RAMP project included 1D-2D flood modeling and risk assessment considering climate change for urban interior flooding, riverine flooding and coastal flooding. The RAMP project will inform and prioritize strategic investments for mitigating risk, based on economic, environmental and social equity criteria, and monetized benefits calculated considering climate change.

SpeakerVan Der Tak, Laurens

Presentation time

11:00:00

11:15:00

Session time

10:30:00

12:00:00

TopicIntermediate Level, Asset Management, Diversity, Equity & Inclusion, Resilience, Disaster Planning and Recovery, Stormwater and Green Infrastructure

Author(s)

Van Der Tak, Laurens

Author(s)Laurens van der Tak1; Elise Ibendahl1; Enrique Lopezcalva1; Demetra McBride1; Rich Dooley1

Author affiliation(s)Jacobs, Silver Spring, MD1

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2022

DOI10.2175/193864718825158566

Volume / Issue

Content sourceWEFTEC

Word count18

Integrating Flood and Heat Risks in AlexRenew's Climate Resilience Plan

Abstract

LEARNING OBJECTIVE
This paper presents an overview of the methods to assess the risk of climate hazards on operations and personnel at AlexRenew, a mid-size wastewater treatment facility in Alexandria, Virginia. AlexRenew's exposure to climate hazards was assessed through site visits, system inspection, data analysis, and flood and thermal modeling. This paper details the methodology used to assess and apply a scoring rubric for probability, impact, and risk of climate hazards on utility operations and personnel. The results of the study provide a method for prioritizing action based on asset risk, including proposed mitigation measures and future design criteria for risk reduction.

INTRODUCTION
AlexRenew, the wastewater treatment authority for Alexandria and parts of Fairfax County, Virginia, has initiated a Climate Resilience Study to understand risks and develop strategies to enhance the resilience of its facilities to climate change impacts. AlexRenew's system includes the water resources reclamation facility (WRRF), interceptors, pump stations, a tunnel system, overflow structures, and administrative spaces. The authority is aware of the growing threats of climate-related hazards and is seeking a robust method for prioritizing systems for protection. The paper includes visualization tools used to analyze and communicate climate-related risks and impacts that inform AlexRenew's climate resilience strategy.

METHODOLOGY
The authors assessed the most acute climate change risks to AlexRenew based on its location, geography, and operations (process shown on Figure 1). Models were developed to assess current and projected risks from flooding, thermal stress, extreme weather events, and other climate variables using SSP5-8.5 greenhouse gas emission scenarios for future conditions projected to 2045, 2075, and 2085.

The vulnerability assessment involved determining the level of exposure and sensitivity of AlexRenew's 5,800+ assets to flooding and heat, distributed across the service area (Figure 2). The authors identified the locations and elevations of potential flood entry to buildings and underground galleries such as doorways, louvers, and stairways, and conducted site visits to categorize, locate, and document assets' elevation and evaluate heat exposure (Figures 3 and 4). Indoor and outdoor thermal modeling was conducted to evaluate future cooling needs and identify heat exposure for assets as well as personnel (Figure 5). A variety of thermal metrics were employed to measure how long and when thermal stress levels exceeded safety thresholds for equipment and personnel. Findings from the Universal Thermal Climate Index (UTCI) model demonstrate a rise in heat stress levels, along with an increase in discomfort hours (Figures 6). Flood modeling was conducted for interior, riverine and coastal flood scenarios (Figures 7 and 8). Sensitivity was based on whether a particular asset would be expected to be inoperable due to exposure to a particular climate hazard. Based on the model results, about 3,500 assets were eliminated from the risk assessment due to low exposure or sensitivity to climate hazards. The risk assessment evaluated and scored remaining assets to determine the probability of a climate hazard causing equipment failure and the resulting impacts to plant operations. Probability scores consider the relative likelihood of current and projected future climate events (Figure 9). Impact scores, which represent the severity of consequence to AlexRenew's operations, were assigned to each system in a manner consistent with the organization's existing methodology to assess assets' risk. The authors determined total risk scores for each asset by multiplying probability and impact scores together. Asset-level probability, impact, and risk scores were then averaged to provide results at the system and facility levels. These scores can be used to prioritize actions to increase resilience. This methodology mirrors the one used to develop the asset management system risk registry, allowing AlexRenew to integrate climate risk scores into its existing risk registry.

RESULTS
The risk assessment results were used to create a prioritized list of assets and systems most at risk of flooding or extreme heat (Figures 10 and 11). The 1,236 assets located in connected underground galleries are most at risk for flooding. As such, implementing flood mitigation measures at entryways is a simple strategy that can improve flood resilience for many critical assets. At-risk systems outside of the galleries require different climate mitigation measures depending on their locations, characteristics, and criticality (Figure 12). The heat risk analysis pinpointed electrical systems and regions with high risk of overheating, which could negatively affect onsite personnel (Figure 13). Personnel were interviewed to determine which facilities were most utilized by staff, which helped identify assets to prioritize for heat mitigation strategies.

AlexRenew will use the results of the Climate Resilience Study to prioritize capital investments and operating procedures to reduce climate risk. Conceptual mitigation strategies are being developed for assets found to be most at risk. A visualization tool is also being developed to illustrate flooding and thermal risk for all facilities.

The results of the Climate Resilience Study are being discussed with facility managers and will be finalized by March 2025.

This paper was presented at WEFTEC 2025, held September 27-October 1, 2025 in Chicago, Illinois.

Presentation time

08:30:00

09:00:00

Session time

08:30:00

09:30:00

SessionBuilding Resilience and Planning for Climate Change

Session locationMcCormick Place, Chicago, Illinois, USA

TopicClimate Change Adaptation and Resilience

Author(s)

Cherry, Charlotte, Lopezcalva, Enrique, Giltinan, Yilin, Sanjines, Paula, Van Der Tak, Laurens, Hatchett, Jennifer, Orme, Mallory

Author(s)C. Cherry1, E. Lopezcalva1, Y. Giltinan1, P. Sanjines1, L. Van Der Tak1, J. Hatchett1, M. Orme2

Author affiliation(s)Jacobs Engineering Group1, Alexandria Renew Enterprise2

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2025

DOI10.2175/193864718825160024

Volume / Issue

Content sourceWEFTEC

Word count11

Description: Preparing for Uncertainty: Climate Resilience Assessment and Adaptation Planning for...

Preparing for Uncertainty: Climate Resilience Assessment and Adaptation Planning for Water Resource Recovery Facilities

Abstract

Introduction
Changing climate can affect wastewater systems in many ways, through changes in temperature, precipitation intensity, duration and frequency (IDF), and magnitude of extreme weather events, and the associated secondary implications such as flooding and wildfires, and sea level rise and coastal storm surge. This paper presents two case studies, focusing on how utilities prepare for the uncertainties of future climate by incorporating climate resilience assessment and adaptation planning into the long-term facility plan of water resource recovery facilities. In addition, one of these case studies addresses greenhouse gas mitigation aspect of climate action planning.
Case Study 1: WSSC Climate Change Vulnerability Assessment Adaptation and Planning
The Washington Suburban Sanitary Commission (WSSC), a water and wastewater utility located in the suburban Maryland outside Washington, D.C., completed a five-year Climate Change Vulnerability Assessment, Adaptation and Mitigation Plan (CCVAAMP) project in 2020. The project included the development of future climate scenarios, modeling of future flood conditions near WSSC facilities, assessment of facility vulnerability and risk, and development of adaptation strategies and cost benefit analysis. The presentation will focus on the study methodology and results from the vulnerability assessment and flood adaptation analysis for the wastewater pumping stations and treatment plants, including:
-Vulnerability analysis, which resulted in a calculated cumulative risk avoided value for each facility based on planning timeline, flood risk, asset replacement costs, and probability of failure of selected strategies (see Figure 1).
-Development of design guidelines for protecting facilities from future climate extremes.
-Annual updates to the WSSC greenhouse gas (GHG) inventory and Action Plan, including GHG mitigation strategy implementation and monitoring (see Figure 2).
Case Study 2: JEA Wastewater/Water System Resilience Plan
JEA is a community-owned electricity, water and wastewater utility located in Jacksonville, Florida. In 2020, JEA completed a System Resilience Plan to further advance its water and wastewater systems toward the goal of being a benchmark resilient utility. This System Resiliency Plan provides enhanced design standards and forwardâ€looking adaptation strategies that will allow JEA to maintain a high level of service (LOS) and minimize system interruptions during extreme weather events across all of its 1,700 facilities, including water, wastewater, reclaimed water and chilled water systems. While JEA has already addressed many of the high-priority and straightforward enhancements, a comprehensive adaptation plan focused on risk reduction, aggressive design standards, and forward-looking capital improvement plan (CIP) investment was developed to further advance JEA's system reliability and resilience.
The presentation will summarize the results of the key tasks completed in preparation of the System Resilience Plan, focusing on findings for the wastewater system, including:
-Vulnerability assessment and risk analysis (see Figure 3)
-Development of mitigation and adaptation strategies, including economic impact and benefit-cost analysis to prioritize implementation (See Figure 4).
-Development of design and construction standards.

Changing climate can affect wastewater systems through changes in temperature, increased risk of nuisance or catastrophic flooding, extreme weather events causing system disruptions, overflows and environmental impacts. This paper presents two case studies on how water and wastewater utilities prepare for the uncertainties of future climate by incorporating climate resilience assessments and adaptation planning: JEA in Jacksonville FL and WSSC Water in MD.

SpeakerVan Der Tak, Laurens

Presentation time

09:25:00

09:40:00

Session time

08:30:00

10:00:00

TopicFundamental Level, Resilience, Disaster Planning and Recovery, Sustainability and Climate Change

Author(s)

Van Der Tak, Laurens

Author(s)Laurens van der Tak1; Miranda Santucci1; Jason Bird1; Oliver Domingo1; Rob Taylor1

Author affiliation(s)Jacobs, Silver Spring, MD1