Tag Archives: groundwater

The reliability of the assets within the area of interest starts with the design process in the asset management plan. Decision-making dictates how the assets will be maintained and effective means to assure the maximum return on investments. Through condition assessment, the probability of failure can be estimated. Assets can also fail due to a growing area that may contribute to exceeding its maximum capacity. Operation and maintenance of the assets are important in reassuring a longer life span as well as getting the most out of the money to be spent. Prioritizing the assets by a defined system will allow for the community to see what areas are most susceptible to vulnerability/failure, which assets need the most attention due to their condition, and where the critical assets are located in relation to major public areas (hospitals, schools, etc.) with a high population.

So what happens when conditions change?  Let’s say sea levels are rising and your land is low.  What would the potential costs be to address this?  Better yet, what happens if it rains? We looked at one south Florida community and the flood stage for each based on 3 storm events: the 1:10 used by FDOT (Assumes 2.75 inches in 24 hours), the Florida Building Code event that includes a 5 in in one hour event (7 in in 24 hrs), and the 3 day 25 year event (9.5-11 inches).

Of no surprise is that the flooding increases as rainfall increases.  Subsequent runs assumed revisions based on sea level rise. The current condition, 1, 2 and 3 ft sea level rise scenarios were run at the 99 percentile groundwater and tidal dates and levels.  Tables 2-5 depict the flood stage results for each scenarios.  The final task was designed to involve the development of scenarios whereby a toolbox options are utilized to address flooding in the community.  Scenarios were to be developed to identify vulnerabilities and cost effectiveness as discussed previously.

The modeling results were then evaluated based of the accompanying infrastructure that is typically associated with same.  A summary of the timelines and expected risk reductions were noted in the tables associated with storm and SLR scenarios.  This task was to create the costs for the recommended improvements and a schedule for upgrading infrastructure will be developed in conjunction with staff.  Two issues arise.  First, the community needs to define which event they are planning to address and the timelines as the costs vary form an initial need of $30 million to over $300 million long-term.  Figure 1 shows how these costs rise with respect to time.  The long-term needs of $5 million per 100 acres matches with a prior effort in Palm Beach County.

SLR costs

Figure 1  Summary of Costs over the 3 ft of potential sea level Rise by 2011, under the 3 storm planning concepts.


If you are a wastewater utility, and you create a high quality effluent product that can be used for industrial purposes, irrigation or aquifer recharge, who “owns” the water?  If the utility is sending to a golf course pond for discharge, the answer seems obvious – the golf course owns it.  Not so fast.

Now let’s day you are recharging and aquifer.  You pump it into the ground with the intention of recharging the aquifer to benefit your wellfield.   Or you pump it into an aquifer storage and recovery system with the intent of recovering it when you need it.  Quick impression is that you should own it, but what about the people that sink walls along the way?  Or have existing wells in the vicinity that can tap your injected water?  Can you keep people from pumping it out?  Not as clear.

What about discharge to a stream with the idea of capturing it downstream in an intake system for your water system?  Much less clear.  The ecosystem, farmers, irrigation users, etc. along the stream could use the increased flows.  Can you keep them out?  Very unclear.

Now assume you are a water rights state and there are people who have rights to the aquifer or stream that are more senior to yours.  Can you clip their claim to the water by claiming the water is yours?  Really not clear and the subject of ongoing regulatory discussion and legal proceedings.

There are no clear answers to these questions but they have major long-term impacts of water resource planning in much of the US.  The problem is the rules assume facts not in evidence at the time of the permit (or claim).  Conditions can change – permits and rules may not (or have not).  Maybe the water regulations and that the changed condition should perhaps obviate the prior claim?  A very tough legal issue and one bound to make a bunch of people unhappy.  The concept of reclaiming water from waste was not a consideration in the past, so clearly the rules that cover reclaimed water need to be revised.  I can’t wait to see the results.

2014 is almost over.  Hard to believe.  I have been attending or annual Florida Section AWWA conference, meeting up with old friends, making new ones and learning new things.  Conferences and connections allow us to do our jobs more efficiently because as we learn how to solve problems or where we can find a means to solve whatever problem we encounter.  It is a valuable experience that I encourage everyone to get involved with, especially young people who need to make connections to improve their careers.  The technical sessions seemed to be well received and popular.  That means that there are issues that people want to hear about.  Things we focused on were alternative water supplies, water distribution piping issues, disinfection byproducts, ASR and reuse projects.

The reuse projects focused on Florida efforts to deal with 40 years of reuse practice and a movement toward indirect potable reuse. This is the concept where we treat wastewater to a standard whereby it can be put into a waterway upstream of a water supply intake or into the aquifer upstream of wells.  The discussion was extended to a number of discussions about water shortages and solutions for water limited areas.  Florida averages 50-60 inches of rain per year as opposed to the 6-10 inches in areas of the southwest or even 15-20 inches in the Rockies which makes the concept of water limitations seem a bit ludicrous for many, but we rely on groundwater that is recharged by this rainfall for most of our supplies, a lack of topography for storage and definitive wet and dry seasons that do not coincide with use.

The situation is distinctly different in much of the US that relies on surface waters or is just plain water limited.  We have a severe multi-year drought going on in California and huge amounts of groundwater being used for irrigation in many rain-challenged areas.  That is what all those crop-circles are as you fly over the Plains states and the wet.  Where you see crop circles, think unsustainable water supplies.  They are unsustainable because there is no surface water and the recharge for these aquifers is very limited.  Most leakance factors in aquifers is over estimated and hence water levels decline year after year.   Water limited places need answers because agriculture often out-competes water utilities, so in the worst of those areas, there are discussions about direct potable reuse (which occurs in Texas).

Direct and indirect potable reuse are offered as answers which is why this topic was popular at our conference.  A recent 60 Minutes presentation included a tour and discussion of the Orange County Groundwater Replenishment program, where wastewater is treated and injected into the ground for recovery by wells nearer to the coast.  They discussed the process (reverse osmosis, ultraviolet light and peroxide) and they took a drink.  “Tastes like water” was Leslie Stahl’s comment – not sure what she expected it to taste like, but it provides a glimpse into the challenge faced by water utilities in expanding water supplies.   Orange County has been injecting water for many years into this indirect potable reuse project.  The West Coast Basin Barrier Project and several others in California have similar projects.  South Florida has tested this concept 5 times, including one by my university, but no projects have yet been installed.

But until recently, there were no direct potable reuse projects where wastewater is directly connected to the water plant.  But now we have two – both in Texas with a number of potential new projects in the pipeline.  Drought, growth, water competition have all aligned to verify that there many are areas that really do not have water, and what water they do have is over allocated.  A 50 year plan to manage an aquifer (i.e.. to drain it) is not a sustainable plan because there may not be other options.  But Texas is not alone.  Arizona, Nevada, New Mexico, Utah, Colorado, The Dakotas, Kansas Oklahoma and I am sure others have verified water limitations and realize that sustainable economic activity is intrinsically linked to sustainable water supplies.  Conservation only goes so far and in many of these places, conservation may be hitting its limits.  Where your rainfall is limited and/or your aquifer is deep, replenishable resource is not always in the quantities necessary for economic sustainability.  Water supplies and economic activity are clearly linked.

So the unimaginable, has become the imaginable, and we now have direct potable reuse of wastewater.  Fortunately we have the technology – it is not cheap, but we have demonstrated that the reverse osmosis/ultraviolet light/advanced oxidation (RO/UV/AOP) process will resolve the critical contaminant issues (for more information we have a paper we published on this). From an operational perspective, RO membranes, UV and chemical feeds for AOP are easy to operate, but there are questions about how we insure that the quality is maintained.  The technical issues for treatment are well established.  Monitoring is a bit more challenging – the question is what to monitor and how often, but even this can be overcome with redundancy and overdosing UV.

But drinking poop-water? The sell to the public is much more difficult.  It is far easier to sell communities without water on the idea, but the reality we need to plan ahead.  There are no rules.  There are no monitoring requirements, but we MUST insure the public that the DPR water they are drinking is safe.  WE are gaining data in Texas.  California and Texas are talking about regulations.  The University of Miami has been working of a project where they have created a portion of a dorm that makes its own water from wastewater.  Results to come, but the endeavor shows promise.

My apologies for being off line for a couple weeks.  We finished the summer semester the first week of August, and are now gearing up for the Fall semester.  Lots to do, and proposals and other projects to complete before the plunge.  The most interesting project this summer has been the conclusion of a national survey of aquifer storage and recovery (ASR) projects.  The concept of ASR wells is to store water underground until you need it later.  If you have a utility with limited water supplies, or if you have high demands a certain part of the year but not the rest, ASR has been touted as a solution.  Storage underground eliminates the evaporation losses, but the question has always been can you get the water back.  The survey, which will be fully published next year, shows 204 sites.  It shows only about a third are operational projects and over 50 that have been functionally abandoned.  The reasons for abandoning them include metals leaching(mostly a Florida problem), the inability to recovery the water (particularly a problem in brackish aquifers), lack of capacity and trihalomethanes (a regulatory issue in a couple states).  ASR was successful with limited injection rates (700 gpm) and where the aquifer was denuddded (South Carolina).  Growth seems to be in the west after a lot of effort in the southeast.  The road forward should prove interesting.  With completion of the study it is hoped that more data can be gleaned to indicate the factors that make ASR project successful, thereby increasing the rate of success for the future. 

Radio Program last week

Hi all.  Here is another radio show I did last week talking about  my company Public Utility Management and Planning Services Inc. and water sustainability. Take a listen. Let me know what you think.  Thanks


The concept of horizontal wells arises from riverbank filtration concepts.  Riverbank filtration has been practiced for nearly 200 year in Europe, where the concept was to remove debris form polluted waters by drawing through the banks of rivers.  Much of the concepts for groundwater flow are related to the filtration ability of water to move through a porous media.  The concept was to dig trenches along the river and draw water from the trenches as opposed to the polluted rivers.  The concept worked relatively well.  The result is an abundant, dependable supply of high-quality water with a constant temperature, low turbidity, and low levels of undesirable constituents such as viruses and bacteria. Riverbank filtration also provides an additional barrier to reduce precursors that might form disinfection byproducts during treatment.

Now let’s look at this from another perspective, and we’ll pick on southeast Florida as is provides a great case study.  Sea level rise will inundate coastal property, both via coastal flooding and from a rise in groundwater. Since most stormwater drainage depends on gravity flow, drainage capacity will suffer as sea level rises reducing the head differential between interior surface waters and tide. Saltwater intrusion will be exacerbated. Furthermore, reduced soil storage capacity, groundwater flow and stormwater drainage capacity will contribute to increased flooding during heavy rain events in low-lying areas.  In low lying areas, current practices like exfiltration trenches will become impractical, as will dry retention will become wet retention.

Stormwater utilities will be faced with dramatic, currently unanticipated increases in capital expenditures and operating costs, and time will be needed for planning, design, securing permits and compliance. Additional local pumping stations on secondary canals will be needed to supplant the storm drainage system in order to prevent unacceptable ponding. Design capacities of these stations will depend on local rain patterns, drainage basin size and secondary canal system design.  Many will operate continuously, which means ongoing operations will increase substantially. Hundreds of pumping stations may be needed in some communities.

Permits will be a major challenge due to contaminants in the runoff as regulated by MS 4 Stormwater permits, and the inability to treat this water under the current structure. The cost and energy required for stormwater treatment would be a major concern going forward. But what if we sent this continuous flow to water plants as raw water?  All of a sudden we have a solution to two problems – stormwater and raw water supplies.  How often do you see a 2 for 1 solution?

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