Tag Archive for: Louisiana

Sand Mining Best Management Practices: Louisiana vs. Texas

When it comes to communicating “best management practices” (BMPs) for sand mines, Louisiana sets the gold standard. The Louisiana Department of Environmental Quality (LDEQ) and the Concrete & Aggregate Association of Louisiana, Inc. worked together to  develop BMPs. Their goals: to reduce the amount of sediment and turbidity in streams and rivers that result from sand and gravel mining and to improve water quality. 

This guide represents a realistic and open approach, which I appreciated. It’s also concise, candid and clearly written. For those who don’t have time to read the entire 41-page document, a  summary follows, especially of the parts that talk about sedimentation. I’ve inserted several images from the East and West Forks of the San Jacinto to contrast practices in Texas and Louisiana.

Importance of Sand and Gravel to Economy

The Introduction discusses the importance of aggregate (sand and gravel) to the Louisiana economy. Sand and gravel are essential resources for construction. In fact, they represent Louisiana’s second most valuable non-fuel natural resource.

Almost half (48%) of all the aggregate produces concrete. The second largest use (22%) is as a base material for highways, railways, runways, etc. 

Types of Mining

The document then discusses different techniques of mining: dry (by excavation) and wet (by dredging). Louisiana focuses primarily on wet, which is the type of mines we have along the San Jacinto with a few exceptions.

Importance of Storm Water Management

Page 4 contains a discussion of “Non-point Source Storm Water Management.” Non-point essentially means from rain, runoff and flooding. It occurs across an entire area as opposed to a specific point, such as a leaky fuel tank. Some key quotes:

“Sand and gravel mining operations can potentially cause off-site impacts to water quality if site planning and BMPs (Best Management Practices) are not factored into every aspect of the mining operation.”

“Sand and gravel mining operations disturb land and soil…”

“Good site planning and operation can reduce the likelihood of sediments moving off of the opera­tion…”

“The purpose of the BMP Manual is to provide informa­tion on the types of BMPs that should be utilized during every phase of the mining operation in order to prevent pollutants from leaving the mining operation.”

Dangers of Not Following BMPs

Page 5 discusses the dangers if miners do not follow best management practices.

“Siltation is considered the highest nonpoint source priority of concern in wetland areas and the second highest priority affecting lakes (1992 Report to Congress). Mining related activities have been estimated to cause 7 percent of the nation’s nonpoint source impacts to lakes and 17 percent to coastal waters. Sediments from mining operations could consist primarily of biologically inert materials which could potentially adversely affect the water body’s designated uses. Inert suspended sediments have the follow­ing detrimental impacts to the aquatic habitat:

  • Sediments smother lower forms of aquatic life in the bottom of a stream. This can destroy the aquatic life in a stream because it kills the food supply. If sedimentation continues with a high concentration of suspended solids, the stream will fail to recover. Sediment deposition may also cover fish eggs and break the life cycle; thereby, destroying the fishery uses of the stream;
  • A continued cloudy condition of a stream will deter its use for almost all recreational purposes;
  • Directly or indirectly, it can change the characteristics of a stream channel and in many instances can limit boat usage and cause additional flooding hazards;
  • In rivers that are utilized for drinking waters, silt creates an additional expense upon the water treatment and purification process for both domestic and industrial users; and
  • It decreases photosynthetic action and thereby reduces the capacity of a stream to assimilate organic matter.”

Recommendations for Soil Conservation

Page 11 marks the start of the discussion about specific BMPs. The first BMP addresses soil conservation. “Sediment loads discharged to streams must be minimized, if not eliminated altogether,” they say. “There are basically two types of controls: vegetative and structural.”

Streambank BMP Recommendations

Regarding the Streambank Best Management Practice (BMP), they say: “When native vegetation is used to maintain streambanks, there are many benefits provided to the public and environment. Near the waters’ edge, herbaceous and wetland plants help filter pollutants from the water and prevent bank erosion during high flow periods. These plants also provide habitat for fish and natural predators of mosquitoes as well as increasing aesthetical appeal. Spatial balance between native trees and shrubs on the streambank provides stability and shading. Shading from trees lowers water temperature and improves water quality by conserving the oxygen in the water.”

Note the images below. The first represents the ideal and was pulled from the Louisiana BMP guide. The others are from sand mines on the West Fork of the San Jacinto and Caney Creek in Texas.

Image of ideal stream bank from Louisiana Sand Mining Best Practices Guide.

West Fork sand mine that has been been repeatedly inundated. Note dikes which have been breached and repaired.

Another portion of the same mine that has been repeatedly inundated. Note width of dike, steepness of slopes, and lack of vegetation to retard erosion. This area is no longer actively being mined.

West Fork sand mines on 8/30/17, one day after the peak of the Hurricane Harvey flood. Note how flood water breached dikes and flowed through mines on both sides of the river. Photo courtesy of Google Earth.

Reducing Erosion through Vegetation

“Vegetation is an inexpensive and effective way to protect soil from erosion,” Louisiana says. “It also decreases erosion from flowing water by reducing its velocity. Roots hold soil and increase infiltration. Topsoil should be added where existing soils are not suitable for adequate vegetative growth.”

Vegetative controls include:

  • Maintaining buffer zones between mine and river
  • Sod stabilization techniques
  • When installed and maintained properly, sodding can be more than 99 percent effective in reducing erosion.
  • Protection of trees involves preserving and protecting selected trees that exist on the site prior to development.
  • Tillage, with lime and fertilizer, to maintain adequate soil pH and nutrient content.
  • Temporary seeding
  • Permanent seeding
  • Erosion & Sediment Control Blankets
  • Surface Roughening – Creating horizontal grooves across the slope to reduce runoff velocity/erosion and aid the growth of seed. 

 Structural Ways to Reduce Erosion

Structural controls include:

  • Diversion ridges, berms or channels of stabilized soil
  • Silt fences
  • Straw bale barriers
  • Sediment basins with banks sloped at 2:1 or less
  • Dikes – Must be well compacted and vegetated, with an outlet pipe or coarse aggregate spillway 
  • Riprap protection – at the outlet end of culverts or channels to reduce the depth, velocity and energy of water so that the flow will not erode the receiving stream.
  • Check dams – Small dams less than 2 feet high constructed across swales or drainage ditches to reduce flow velocity and erosion.
  • Aggregate stabilized site entrances – at least 50 feet long to reduce sediment tracked onto public roads. Tire washing may also be needed.
  • Good housekeeping practices for fuel, debris, sediment from unstabilized areas, etc.
  • Post-construction stormwater management measures
  • Retention ponds
  • Vegetated swales and natural depressions that filter sediments from runoff with side slopes of 4:1 or less.

Best Management Practices for Land Clearing

Regarding land clearing, Louisiana recommends:

  • Disturbed areas should be temporarily stabilized or covered as soon as possible to minimize impacts on the environment.
  • Only clear acreage needed for immediate use. Clearing or grubbing too much land too early in the construction phase of the mining operation will dramatically increase the potential for environmental impacts from surface water runoff and will increase the costs to control runoff. 
  • Allow enough undisturbed buffer at property boundaries to provides sufficient lateral support of property lines. 
  • A minimum 100-foot buffer zone is required adjacent to perennial streams and water bodies in the State of Louisiana.

In a mine on Caney Creek,this 64-acre area was cleared a year and a half before Harvey, but was not mined. The lack of vegetation made it more susceptible to erosion during the flood. Photo taken 9/14/17, two weeks after Harvey.

Site Reclamation Goals and Best Management Practices

Pages 28-31 describe best practices for site reclamation. Goals include:

  • Stabilization of inactive mining pit or borrow areas with herbaceous perennial plants
  • Stabilizing the soil
  • Preventing wind or water erosion from causing on-site or off-site damage
  • Improving the aesthetic appeal
  • Ability of the site to support wildlife

Best management practices include:

  • Revegetation, mulching
  • Grading slopes 3:1 to facilitate seeding
  • Constructing diversions at tops of slopes to divert runoff away from the slope banks to a stable outlet 
  • Constructing aggregate lined chutes or equivalent to conduct concentrated flow of water to stable outlets 
  • Reclamation of abandoned roads by reshaping, recontouring, and resurfacing with topsoil and seeding for vegetative growth
  • Removal of structures 
  • Removal of sand stockpiles
  • Removal of debris
  • Grading property to minimize potential impact to waterways

Abandoned sand mine in Humble, TX. No fencing. No grading. No vegetation on slopes. Note proximity to buildings on adjoining property and road. 

Concrete crushing operation once part of sand mine in Humble, TX. 

Education Better Than Damage Control

In the conclusion on Page 32, Louisiana states:

“One of the best ways to mitigate environmental impacts from the sand and gravel industry in Louisiana is to establish a set of volun­tary best management practices for the industry to adhere. This can be accomplished by initiating good management practices, educating our operators, and taking a more proactive stance in minimizing the problems of the past that have hurt this industry’s image. We, as industry leaders, need to be actively engaged in addressing issues and taking precautions and preemptive measures. Damage control after the fact is destructive. The world is changing and we must be adaptive to these changes – good management practices in an environmentally friendly manner are synonymous with good business practice.”

I’m sure Louisiana has problems just like Texas. But I sure do like the tone of this and what they are trying to accomplish. If Texas has a similar initiative, I can’t find it.

Posted 8/19/18 by Bob Rehak

355 days since Hurricane Harvey

Do Local Sand Mines Follow Best Management Practices?

Note: This is the first article in a series on sand mine best management practices. It focuses on insufficient natural buffers between the mines and the San Jacinto river. Subsequent posts will focus on land clearing, site reclamation practices, and more.

A comparison of sand mining actual and best management practices found that performance shortfalls in local mines exacerbate sedimentation in the San Jacinto River, contrary to assertions by the Texas Aggregate and Concrete Association (TACA) that sand mining has environmental benefits.

Proximity of mines to San Jacinto River in non-flood conditions.

TACA claims that when a river floods, the current is so weak that sand and sediment are deposited inside of mines. An analysis of satellite and aerial photos shows, though, that the current is strong enough to break dikes, destroy roads, re-route the river through mines, and carry sediment downstream.

TACA sounds eerily reminiscent of Richard Pryor when his wife caught him in bed with another woman. “Who you going to believe? Me or your lyin’ eyes?”

In at least one case, a broken dike has gone unrepaired for years while pollution continues to escape into the San Jacinto, the main source of water for Lake Houston and millions of people.

Dangers of Sand Mining

Numerous states and countries acknowledge the following risks of sand mining. Most impose regulations on the industry because sand and silt washed downstream from mines can:

  • Impair water quality
  • Increase water treatment costs
  • Impair wildlife and fish habitat
  • Reduce carrying capacity of rivers and streams
  • Reduce the volume of lakes
  • Block drainage ditches
  • Contribute to flooding
  • Impose dredging expenses on taxpayers
  • Ruin recreation

Louisiana: Leader in Communicating Best Practices

The Louisiana Best Management Practices Guide to sand mining is one of the most concise, candid and clearly written guides in the world. Government and industry developed it together. The refreshingly honest introduction states:

  • “Sand and gravel mining operations can potentially cause off-site impacts to water quality if site planning and BMPs are not factored into every aspect of the mining operation.”
  • “…BMPs … should be utilized … to prevent pollutants from leaving the mining operation.”
  • “Siltation is considered the highest nonpoint source priority of concern in wetland areas and the second highest priority affecting lakes (1992 Report to Congress).”
  • “Mining related activities have been estimated to cause 7 percent of the nation’s nonpoint source impacts to lakes and 17 percent to coastal waters.”

Comparing Texas Practices to Other Areas’

Texas does not make it clear what the state’s best management practices (BMPs) for sand mines are. So how do sand mines along the San Jacinto measure up to other states’ and countries’ guidelines? Not well.

One focus of their BMPs is the use of buffer zones, setbacks and strips of vegetation to reduce erosion and control sedimentation. The minimum distance between mine and river in most cases is 100 feet. Some specify more.

  • Alaska, for instance, discourages mines from locating within 1000 feet of a public water source, i.e., the San Jacinto which feeds Lake Houston, the main drinking water source for millions of people. The minimum near other bodies of water in Alaska is 200 feet.
  • Malaysia specifies a 50 meter setback (164 feet) from all river channels.
  • Australia prohibits sand mining in sensitive areas altogether.

In Texas along the San Jacinto, miners often excavate to within 40-50 feet of rivers, and remove vegetation to build dirt roads on the remaining narrow strip between the mine and the river. These thin, sandy barriers provide little defense against floods. They have been repeatedly breached, as you will see below. The river often runs right through mines, carrying sand and sediment downstream.

Types of Barriers against Sedimentation

Louisiana mandates a minimum 100-foot buffer adjacent to perennial streams. The state recommends a dual defense against sedimentation: vegetation and structural measures. Their best practices guide states, “Vegetation is an inexpensive and effective way to protect soil from erosion. It also decreases erosion from flowing water by reducing its velocity. Roots hold soil and increase infiltration. Topsoil should be added where existing soils are not suitable for adequate vegetative growth.”

Vegetative controls include:

  • Maintaining buffer zones between mine and river
  • Sod stabilization techniques. Sodding can be more than 99 percent effective in reducing erosion.
  • Protection of trees involves preserving and protecting selected trees that exist on the site prior to development.
  • Temporary and permanent seeding

Structural controls include:

  • Diversion ridges, berms or channels of stabilized soil
  • Silt fences
  • Sediment basins with banks sloped at 2:1 or less
  • Dikes – Must be well compacted and vegetated, with an outlet pipe or coarse aggregate spillway
  • Riprap protection – at the outlet end of culverts or channels to reduce the depth, velocity and energy of water so that the flow will not erode the receiving stream.
  • Check dams – Small dams less than 2 feet high constructed across swales or drainage ditches to reduce flow velocity and erosion.
  • Aggregate stabilized site entrances – at least 50 feet long to reduce sediment tracked onto public roads. Tire washing may also be needed.
  • Good housekeeping practices for fuel, debris, sediment from unstabilized areas, etc.
  • Post-construction stormwater management measures
  • Retention ponds
  • Vegetated swales and natural depressions that filter sediments from runoff with side slopes of 4:1 or less.

A Visual Comparison

Note the images below. The first represents the ideal; it is taken from the Louisiana BMP guide. The rest are from the West Fork of the San Jacinto in the last three years.

Image of ideal stream bank from Louisiana Sand Mining Best Practices Guide. Note vegetation, grass, gradual slope and aquatic plants.

West Fork Sand Mine,  9/14/2018. During Harvey, 150,000 cubic feet per second came rushing down this narrow channel and flooded 20 square miles of exposed sand in more than a dozen different mines.

Consequences of NOT Following BMPs

The image above and the following images all come from a small area of investigation shown below.

2.1 miles from Northpark Drive and US59, and 3.1 miles upstream from the US59 bridge.

The following images demonstrate what happens when miners work too close to the river. Numbers on the first image correspond to close-ups that follow.

Inundation of sand mines during Harvey on 8/30/17. Numbers correspond to close-ups below.  All photos courtesy of Google Earth.

1 – Rapids within sand mine.

2 – Water rushing into mine, creating turbulence.

3 – Water takes a shortcut across meander through mine.

4 – Washed out road INSIDE sand mine during Harvey. 

5 -Sand bars within sand mine in conjunction with ruptured dikes prove sand was carried downstream. Photo taken on 10/28/2017 (after Harvey).

In a white paper circulated among Texas state legislators called The Societal and Environmental Benefits of Sand MiningTACA insists, “When [water invades a sand mine during a flood], the velocity of the water slows significantly, losing its ability to keep sediments in suspension and the stream or river begins to deposit its sediment load. When flood waters back into an area where a sand and gravel pit is located, the pit becomes a sediment trap for the flood waters and their sediments.” This series of photos directly refute TACA’s claims.

Why do we allow sand mines to operate in areas that flood repeatedly and violently, so near the drinking water source for millions of people?

Un-repaired Dike Still Leaks Sediment after 3 Years

Are the mines following Best Management Practices? The dike on the right in the images below ruptured in 2015 and still has not been repaired. Note sediment streaming into the West Fork.

Dike ruptured during flood in 2015 (see image below). It continues to spew sediment into the river.

Geologists say that once a river “captures” a sand mine, it repeatedly tries to take that same route in subsequent floods. This is a direct consequence of mining too close to the river. 

Cautionary Advice from India

Sustainable Sand Mining Management Guidelines from India state, “Floodplain Extraction should be set back from the Main Channel. In a dynamic alluvial system, it is not uncommon for meanders to migrate across a floodplain. In areas where sand and gravel occurs on floodplains or terraces, there is a potential for the river channel to migrate toward the pit. If the river erodes through the area left between the excavated pit and the river, there is a potential for “river capture,” a situation where the low-flow channel is diverted though the pit. In order to avoid river capture, excavation pits should be set back from the river to provide a buffer, and should be designed to withstand the 100-year flood… Adequate buffer widths and reduced pit slope gradients are preferred over engineered structures which require maintenance in perpetuity.”

Sand Miners Externalize Costs

Because these West Fork sand mines did not consider violent floods in their design and construction criteria, taxpayers downstream bear the cost of remediation. Dredging of the West Fork will cost tens of millions of dollars – for the initial 2.1 mile phase alone! That doesn’t even include recurring and unnecessarily high costs of water treatment because of turbidity.

Posted 6/24/18 by Bob Rehak

299 days since Hurricane Harvey