StormCon 2017 - Stormwater Management at Facilities - Draining to Sediment Superfund Sites

Philip Spadaro, TIG Environmental, Seattle
Jeff Gabster, TIG Environmental, Seattle
Stefano Biondi, StormwaterItalia, Venice, IT
Francesca Sambo, StormwaterItalia, Venice, IT
Barry Kellems, Integral Consulting Inc., Seattle
August 27–31
Bellevue, Washington
Stormwater Management at Facilities
Draining to Sediment Superfund Sites

Copyright © 2017 TIG Environmental2
Introduction
• Stormwater is largely an issue managed under the Clean
Water Act
• The intersection of the Clean Water Act and the Superfund
Law has many challenges
• Managing stormwater at facilities draining to sediment
Superfund sites is particularly challenging
– Emphasis on pollutant source control
– Substantial financial exposure
– Potential for sediment contamination
– Threat of future recontamination

Environmental Management in Urban
Industrial Waterways

Hypothetical Facility
• A recreational marina and boatyard
– Typical site activities:
• Upland boat storage
• Light boat maintenance and repair
• Boat cleaning via pressure washing
• Vehicle traffic onsite
– Goals:
• Evaluate and reduce the impact of stormwater on water/sediment
quality in the adjacent waterway
• Reduce typical marina/boatyard related Contaminants of Concern
(COCs)
– Copper, Zinc, Lead, etc.

Conceptual Site Model of a Boatyard

Reducing Stormwater Loads to the
Receiving Waterbody
– spent abrasive grit
– spent solvent
– spent oil
– wastewater from pressure-
washing
– paint over-spray
– paint drips
– various cleaners and
anticorrosive compounds
– paint chips
– scrap metal
– welding rods
– wood
– plastic
– resin
– glass fibers
– miscellaneous trash such as
paper and glass
• Wastes generated by boatyard activities include:

Reducing Stormwater Loads to the
Receiving Waterbody
• Means of pollutants entering the wastewater stream:
– the application of paint and preparation or cleaning of and painted
surfaces
– the handling, storage, and accidental spills of chemicals, leaks, or
drips of paints, solvents, or thinners
– the fracturing and breakdown of abrasive grits
– and the repair and maintenance of mechanical equipment

Progress in Reducing Environmental
Footprint
• NDPES permit requirements provided the initial impetus for
improving management of boatyard stormwater and
effluents
• Washington State specific permit requirements:
– Limitation of discharges
– Implementation of mandatory best-management practices (BMPs)
– Implementation of monitoring and sampling requirements
– Development and management of a stormwater pollution
prevention plan (SWPPP)
– Report submittal and record maintenance

Voluntary, Incentive-based Programs
• Clean Boatyard Washington was created in 2005
– Puget Soundkeeper Alliance, Northwest Marine Trade Association,
and EnviroStars Cooperative.
– Supported by funded by Washington Department of Ecology
– Certified 14 marinas

Result: Mean Copper Concentration in
Boatyard Runoff, 1998-2014
Year Mean Copper Concentration (µg/L)
1998-2002 410 µg/L
2006-2008 110 µg/L
2011-2014 31 µg/L

Proposed Approach
• At boatyards, vessel hulls are commonly cleaned via
pressure washing, a water-consuming process
• Typical contaminants in boat wash water may include
suspended solids, volatile and semi-volatile organic
compounds, detergents, and metals
• Approaches to wastewater management:
– Collection of wastewater for truck transport to a disposal facility,
such as a publicly owned treatment works (POTW)
– Discharge to a sewer for treatment at a POTW
– Onsite treatment for reuse

Closed-Loop Wastewater System
• Example system for treating wastewater onsite for reuse in
pressure washing
– Process Steps:
• Flocculation and settling: wastewater dosed with flocculant is conveyed
to settling tank where flocculated particles settle out, and removed as
settled solids
• Filtration: wastewater passes through a polishing filter to remove
additional fine materials
• Storage: holding tank is used to provide a continuous, on-demand feed
to the pressure washer
– Additional treatment options:
• pH control, precipitation, adsorption, ion exchange, electrocoagulation,
and/or membrane treatment

Concerns Related to Closed-Loop System
• Removal and disposal of settled solids
– Municipal landfill vs. hazardous-waste disposal
– Loss of water from system requires replacement
• Interaction between stormwater and wastewater system
– Wastewater cannot pass to stormwater system
– Stormwater overflow cannot flood wastewater system
• Solutions
– Separate treatment systems for stormwater and wastewater
• Stormwater: variable volume, low contaminant concentration
• Wastewater: regular volume, high contaminant concentration
• Allows treated stormwater to be diverted to replace lost wastewater
during solids disposal

Process Flow Diagram (PFD) of Onsite
Wastewater and Stormwater Management System

Preventing Spills from Reaching the
Waterbody
• A monitoring and emergency response system should be
implemented to prevent spilled materials from reaching the
waterway.
• Unintended discharges may result from either accidental
events or incorrect operation of the treatment system.
• Once such an event occurs, unintended contaminants
and/or untreated water can be rapidly conveyed through
the drainage system to the receiving waterbody.

Requirements for Controlling Unintended
Discharges
• Detection of unintended discharges, including those of
unknown or unpredicted substances
• Rapid detection of changes in water quality to identify
spills and treatment system failures as they occur
• Rapid reaction to immediately divert untreated flow away
from the outfall and sound an alarm.
• Simple operation and maintenance.
• Flexibility to be applied at multiple locations, yet adaptable
for site-specific needs.

SWERM®: Stormwater Emergency Risk
Management
• Developed to manage and
control spills, and thus
prevent potential acute
impacts to the waterbody
• Continuously monitors and
records a number of basic
parameters (e.g. pH,
turbidity) in a pipeline.
• Automatically closes valve
upon detection of significant
change in water quality.

Features/Functions of the SWERM®
• Capable of diverting flow immediately upon detection of
changes in water quality.
• Measurement range can be adjusted by the operator to
account for the site history.
• Continuously monitors the drainage system and can detect
an abnormal condition in real time
• Activates an alarm and closes the pipeline to prevent
unintended discharges from reaching the waterbody.
• Flow is diverted to a holding tank, rather than to the outfall,
to collect the potentially contaminated water and allow time
for system operators to respond.

Modeling the Potential Impact on
Sediment Quality
• Accurate estimation of the potential impact of discharges
from a facility on sediment quality is important in assessing
treatment priorities and cost-benefit analyses.
– Particularly pertinent for facilities located on a waterway Superfund
site, where costs and potential liability may increase significantly.

Modeling Process Components
• Modeling mass COC loading via stormwater discharge
– Identifying the concentrations of COCs present in stormwater at a
site or discharge location.
– Calculate volumetric flow from the precipitation rate and connected
drainage area.
– Annual estimates of loading can then be estimated via the Simple
Method, which defines annual loading as the product of annual flow
volume and COC concentrations in stormwater.

• Modeling fate and transport of particulate-associated
COCs once they enter the waterway to estimate where
they will settle
– As COCs enter a waterway their fate is primarily determined by the
hydrodynamics and sediment transport characteristics of the
receiving waterbody.
– Requires development of coupled hydrodynamic and sediment
transport models of the waterway
– Provides detailed quantitative annual COC loading estimate across
the waterway sediment bed.

• Modeling COC concentrations in sediments due to
deposition over time
– Using the SEDCAM model, annual COC load to sediments
calculation can be used to estimate the long-term sediment
concentration of COCs due to stormwater loading from a specific
source
– The SEDCAM model is a one-dimensional mixing model that
evaluates source loading, sediment deposition, chemical-specific
degradation rate, and mixing

What is SEDCAM?
• Sediment attenuation model that follows a mass balance approach
to evaluate source loading, sediment deposition, and chemical-
specific degradation rates developed by Jacobs, Barrick, and Ginn
in 1988 (Jacobs et al. 1988)
• Three main processes included in model important in predicting
future sediment concentrations: burial, mixing, and loss by diffusion
and/or degradation (Jacobs et al. 1988).
• Assumes sediment mixing layer (user defined).

Model Predicted Sediment COC
Contribution from Stormwater
• SEDCAM model was developed for the Washington Department of
Ecology to estimate natural recovery of contaminated sediment
• SEDCAM model has also been used at other sites as a screening
step for contaminants
• SEDCAM model is relatively conservative and simple model which
is one of its main strengths
• Can be used in conjunction as a “stacked model” with results from
hydrodynamic model used to define sediment depositional areas

Model Predicted Sediment COC
Contribution from Stormwater

Result of Modeling Process
• Three modeling steps applied in combination to provide a
detailed estimate of potential stormwater impacts on
sediment quality:
– Simple Method to estimate stormwater loading
– Coupled hydrodynamic and sediment transportation model to
estimate bed depositional loading
– SEDCAM to estimate sediment bed COC concentrations over time

Conclusions
• Revisiting the key steps:
– Implementation of BMPs to reduce stormwater contamination from
typical facility activities
– BMP application record and maintenance log
– Implementation of an integrated management treatment plan that:
• Treats and recycles pressure washing water
• Separates stormwater for efficient treatment
• Provides the possibility to reuse treated stormwater onsite
– Implementation of SWERM® devices to monitor outfall water quality
and to automatically divert abnormal flows in real time to prevent
unintended discharges.
– Modeling of stormwater impacts to sediments to assist in
stormwater management planning and design.

Thank You
Questions?

StormCon 2017 - Stormwater Management at Facilities - Draining to Sediment Superfund Sites

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