Total Water Management on the Barrier Island Complex ... · Barrier Island Complex, Currituck...

Total Water Management on the Barrier Island Complex, Currituck

County, North Carolina

By: Ed Andrews

Edwin Andrews & Associates, PC

Raleigh, N.C.

Part 1 - Barrier Island Complex

• A Barrier Island is a relatively isolated hydrologic system • A Barrier Island is most likely at or near sea level • Barrier Islands can move laterally as much as a couple

hundred feet for a foot of sea level fluctuation • That is how the Barrier Island forms, they are dynamic • The Beach Side has Coarser Sand that the Sound Side • Frequently (geologic perspective) new inlets are formed by

pressure from behind on the finer sediments • Maritime Forests on Sound Side are a Major Discharge

Mechanism for Water Off of the Island

What is a Barrier Island?

Can you see the Barrier Island?

Generally, Ocean Currents run North to South (Littoral).

Transition of Continent to Atlantic Ocean, Always Changing and Moving with Sea Level Rise or Fall

Currituck Beaches

The Barrier Island is a Narrow Strip

Coarsest Sediments on Beach

Part 2 - Total Water

• We all have perspectives about water from our experiences;

o Well Drillers;

o Water Resource Engineers;

o Hydrogeologists;

o Soil Scientists;

o Hydrologists;

o Oceanographers;

o Climatologists;

o Limnologist;

o Chemists;

Early Water Shortfall

“Currituck County Outer Banks Water Supply Study”, NC Division of Water Resources, November 1991

• Identified Potential for Water Reuse

• The report concluded consumption was significant

What is Consumption?

Water Withdrawn less Wastewater net average consumption was 62%.

That lead me to wonder how can 62% of the water be consumed?

Possible consumption.

• Perspiration.

• Water and Ice transported off of the barrier island. How much is added – Beer, Ice, etc.

• Trucking off biosolids 98% water.

• Spray irrigation using Potential Evapotranspiration and Evaporation.

• Using the Atlantic Ocean as a bathroom.

-Total Water Includes-

• Well Water

• Groundwater

• Drinking Water

• Surface Water

• Ice and Snow

• Wetlands

• Floods

• Rainwater

• Storm-water

• Wastewater

• Contaminated Water

• Saltwater

• Water Vapor

A Point & A Joint and Septic Drainfield

Shallow Wells & Salt

Well Fields Expanded with Significant Drawdown – Leading to More Salt

The Addition of RO was Proposed

Currituck Outer Banks Aquifers Hydrologic Cycle

Conceptual Diagram showing a two part Yorktown Aquifer, as found on the Currituck Mainland.

Only the deeper Yorktown Aquifer was found present on the Barrier Island

By 2002, a New Source was Found The Yorktown Aquifer on Part of the Barrier Island

1. Then from 1999 to 2002, The Deeper Semi-Confined Yorktown Aquifer was Found and Characterized

2. The Thickness and Hydraulic Conductivity varied Greatly

3. The Quality in the Permeable Areas was Consistanly +/- 1500 mg/l Chlorides

4. A Reverse Osmosis Plant was built

3 – D View of Beach

• Upper Gray is Holocene to Recent sands that form the Surficial Aquifer or the Beach as we see it

• The tea is an area underlain by a low permeability clay

• The blue is a moderately permeable clay that separates the surface sand, with the rainfall recharge, etc. from the Yorktown Aquifer.

• The Green part of the Yorktown Aquifer may reflect a Paleo-channel (old channel or inlet).

• Well Yields in the green part of the Yorktown produce more than 1 mgd

Part 3 – The Dark Side What to do with the wastewater? The Beach is already wet.

Now 4.0 million gallons per day will be pumped from the Yorktown Aquifer and added as wastewater to the Barrier Island.

Can wastewater be a resource?

Plenty of Water

Not all of the water is good.

Yes, at times maybe too much?

(By the way the best surfing is south near Hatteras.)

The Barrier Island has had significant problems meeting the water supply needs using the shallow (surificial) aquifer, until 2002, with the development of the deeper Yorktown Aquifer and the addition of RO treatment for the southern part of the Barrier Island.

The shallow wells have salt water intrusion from May to August to over 700 mg/l chlorides.

Wastewater to the rescue

• Facts about the Currituck County Outer Banks

– Area = 11,500 Acres (Currituck GIS)

– Avg. Rainfall 47 inches (NRCS)

– 40,208,750 gallons per day

– Avg. Jan. Rainfall 3.7 inches (NRCS)

– Avg. July Rainfall 5.26 inches (NRCS)

– Can get Hurricanes +12 inches

– Winter Population – 7 to 10% of Summer

– Avg. Jan Temperatures – 41.2

– Avg. July Temperatures – 77.6

– Water Supply – 4,000,000 gallons per day

Concepts for Wastewater Systems

1. Septic Tank Disposal

2. Treatment and High Rate Disposal

3. Spray Irrigation

4. Limited Water Reuse

5. High Rate Infiltration

6. Conversion to Groundwater

7. Dune Stabilization

8. Wetland Augmentation

9. NPDES Discharge

Water Reuse Considered from 1995 to 2006, However, no Place to Store Wastewater

High Rate Systems

• NC Requires Nutrient Reduction in Tight Areas such as the Currituck Outer Banks to Total Nitrogen of less than 4mg/l,

• Load on to the sand up to 10 gpd/sq ft

• Can add groundwater lowering at 50 feet with the reduced nutrients

• Lowered Groundwater (Drains) is officially restored to the Hydrologic Cycle.

High Rate Concept

PART: 4 – STORM WATER

Resolved: - Water Supply and Wastewater Disposal

The Remaining Problem – Storm water, Sea Level Rise,

Wetland Protection

Part 5 - Total Water Management Mimics the Hydrologic Cycle

Water & Wastewater Problems Solved ?!?

New Problem water quality of the surficial aquifer and flooding.

Old Septic tank drainfields become a problem

Every House had drainfield, that lead to this flooding with one week after Hurricane Ernesto 2006

The main problem is the most of the Flooded areas are 6 to 8 feet above mean sea level, with a clay perching a temporary water table

January – Flooding

Stormwater – An Active Approach

A Passive Approach

Linking Stormwater (interstitial) with Water Supply – Saltwater Intrusion Control

Part 5 – Total Water Management Tasks left to do – Discussion - Which Water Component Applies: 1) Clean up Septic Tanks 2) Provide Storage for Normal <100 yr storm events 3) Prevent or Reverse Salt Water Intrusion 4) Provide Safe Stormwater management 5) Manage Wastewater Recharge 6) Control water levels 7) ASR 8) Artifical Recharge 9) Wetland Management

One PROBLEM: How to Navigate Regulations while Satisfying the equation simply stated: Qin = Storage + Qout

The Perspectives of Our Professions

Is Influenced by Federal Agencies U.S. E.P.A. U.S. Department of Health U.S. G. S. Corps of Engineers N.R.C.S. N.O.A.A. Interstate Commerce Commission H.U.D.

State Agencies

NC Department of Environment and Natural Resource NC Department of Health NC Department of Transportation

Part of the History of Total Water Management - U.S.G.S.

• USGS - Based on “Report on the Lands of the Arid Region of the United States”, John Wesley Powell, 1878 – Water was identified as the region’s , precious resource.

• 1894, geology was extended to water...

• Early pollution from sawmills was identified by early US Geological Survey Hydrographers

• By 1928 the Water Resources Branch was developing quantitative data regarding ground-water and surface water

• In 1946 the Water Respources Branch appointed new chiefs of “Surface Water, Ground Water and Quality of Water Divisions.”

Segmenting Water – Need to Recombine

• By 1940’s, Conjunctive use was recognized as paring two distinct water systems based on the hydrologic characteristics of each. Specifically, Nebraska, Texas, California and other western states were experiencing the drawdown and associated effects of taking groundwater at a greater rate than recharge could support.

• On the other hand surface water sources were only seasonal, typically.

• This leads to current concepts such as Aquifer Storage and Recovery

To Do - Lets Discuss Your State or Province

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