Placing all the sediment that is removed from pond- Aug 25 & 26

The removal of sediment from the pond has always been one of the fundamental goals of this project. Our plans, as approved by MDEQ, very clearly states what is the amount permitted to be removed from the pond and displaced on the TNC site (approx. 1,100 cubic yards).

If you recall (see our July 17th post) the heavy clay material that was found to be suitable for the expansion and reinforcement of the berm, was to be be dug, transported within the pond, and used as such. The sediment, which is composed of more muck and peat, was to be disposed at the OHAC access site (near parking lot), the Anita Jones access site (north of OHAC parking lot), the amphitheater, and used to re-construct the nesting island.   Based on the original plans we were also to take this sediment that was being removed from the pond and transported within the confines of the pond (with minimal use of trails) to the specified disposal areas.

Once again on-site conditions of the pond (i.e. the amount of water, saturated sediment, and the inability to find the required clay) changed the disposition, placement, and transport of the sediments that have been removed from the pond. The berm was built using imported clay. The nesting island is still being built with sediment from the pond. The OHAC access site (near parking lot) will still get sediment from the pond. There is no sediment going to the Anita Jones access site (north of OHAC parking lot) and very little (if any) to the amphitheater. The remaining sediment is now being placed on the Thurston school grounds.

Pond Circle Trail was widen for vehicles like the Morooka

Pond Circle Trail was widen for vehicles like the Morooka

Morooka is loaded with sediment at the outlet channel then travels down Pond Circle Trail toward amphitheater

Morooka is loaded with sediment at the outlet channel – then travels down Pond Circle Trail toward amphitheater

Morooka makes a right hand turn by amphitheater and heads to school playground

Morooka makes a right hand turn by amphitheater and heads to school grounds

Morooka dumps sediment at school grounds

Morooka dumps sediment at school grounds

Caterpillar moves piles which will allow more sediment to be dumped

Caterpillar moves piles which will allow more sediment to be dumped

On the 25th we had this much sediment

On the 25th we had this much sediment

On the 26th we had a bit more sediment

On the 26th we had a bit more sediment

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Berm gets re-graded and extension into peninsula is completed- Aug 24 & 25

While some were working on excavating the pond the remainder of the crew was putting finishing touches on the berm. With some added imported clay, and re-grading on the 24th and 25th the berm work is almost complete.

The berm being re-graded – making it stronger, wider and a bit higher

The berm being re-graded – making it stronger, wider and a bit higher

The portion toward the pond is just a bit higher

The portion toward the pond is just a bit higher

More imported clay is brought in to finish the berm in the peninsula

More imported clay is brought in to finish the berm in the peninsula

Sand bags and rocks that were once used as a temporary dam were removed and a “proper” berm extended into peninsula

Sand bags and rocks that were once used as a temporary dam were removed and a “proper” berm extended into peninsula

Looking northwest from Pond Circle Trail – the Peninsula Trail on the southwest side of the peninsula is now part of our overall Berm

Looking northwest from Pond Circle Trail – the Peninsula Trail on the southwest side of the peninsula is now part of our overall Berm

The west side of the Peninsula Trail - looking south from within the peninsula

The west side of the Peninsula Trail – looking south from within the peninsula

The main berm on Pond Circle Trail - looking southeast toward the peninsula – grading almost complete

The main berm on Pond Circle Trail – looking southeast toward the peninsula – grading almost complete

Our berm – looks good and hopefully will last for many more years to come

Our berm – looks good and hopefully will last for many more years to come

Excavation work continues- Aug 24 & 25

It was a long two days (24th and 25th) – the Anglin Civil construction team was on site each day for 14 hrs. (7AM to 9PM). This morning they started once again at 7AM and got right to work on continuing to excavate the pond as well as to complete the berm.

The sequence of the excavation has been

  • The deep water pool (upstream of the outlet channel)
  • The channel off-shoot to the southeast
  • The channel off-shoot to the northwest

Work on excavating the pool and using the sediment to build the Nesting Island was mostly completed late on the 24th and early on the 25th 

Excavation site – just north of outlet channel - on south side of pond

Excavation site – just north of outlet channel – on south side of pond

Pool is almost complete – a lot of water needs to be drained

Pool is almost complete – a lot of water needs to be drained

Water being pumped out of pool – mostly coming from the north thru a clay pipe (?)

Water being pumped out of pool – mostly coming from the north thru a clay pipe (?)

Sediment excavated from the pool was mainly kept on site and used to build Nesting Island.

Our “new” Nesting Island

Our “new” Nesting Island

I believe the wildlife will appreciate this new island – what should we plant on it?

I believe the wildlife will appreciate this new island – what should we plant on it?

From Pond Circle Trail through the outlet channel and into the pond, the area had to be cleared and widen. The Morooka was used to haul the sediment from the channel excavations to the designated disposal sites.

Widening the work area to allow the Morooka to transport sediment

Widening the work area to allow the Morooka to transport sediment

Once the main pool was “more or less” complete, the plan was to start excavating the channel-off shoot going to the southeast. Unfortunately, the amount of water and saturated sediment prevented us from excavating the channel to the length shown in the plans. So, as an alternative, an “on-site” decision was made to make it shorter but wider, so as to have the same volume.

Water being pumped out of southern portion of pond by amphitheater

Water being pumped out of southern portion of pond by amphitheater

Rob (ECT), Ken (Anglin), Luke & Josh (Anglin), Alice (ECT) – reviewing situation to the southeast

Rob (ECT), Ken (Anglin), Luke & Josh (Anglin), Alice (ECT) – reviewing situation to the southeast

Feasibility of placing the excavator in pond to create the channel being discussed

Feasibility of placing the excavator in pond to create the channel being discussed

Excavator on wooden mats moving into position to dig channel

Excavator on wooden mats moving into position to dig channel

Excavator and mat starting to sink

Excavator and mat starting to sink

Rob and Alice (ECT), Josh and Luke (Anglin) breathing a sigh of relief – excavator is saved and a good but nervous laugh at what happened last time

Rob and Alice (ECT), Josh and Luke (Anglin) breathing a sigh of relief – excavator is saved and a good but nervous laugh at what happened last time

Excavator and Morooka on mats – excavating, loading, and transporting sediment from channel to disposal area

Excavator and Morooka on mats – excavating, loading, and transporting sediment from channel to disposal area

Channel off-shoot headed southeast from pool almost completed

Channel off-shoot headed southeast from pool almost completed

Pool and channel headed southeast connected

Pool and channel headed southeast connected

Excavator heads west on “wooden road” to work on the other channel off-shoot directed northwest

Excavator heads west on “wooden road” to work on the other channel off-shoot directed northwest

Water has to be pumped out of northwestern side of pool before digging new channel

Water has to be pumped out of northwestern side of pool before digging new channel

Digging begins on the northwestern channel – decision made to make shorter and wider like the other channel

Digging begins on the northwestern channel – decision made to make shorter and wider like the other channel

Channel being excavated is fed a lot of water from clay pipe that must have been placed in pond over 60 years ago (?)

Channel being excavated is fed a lot of water from clay pipe that must have been placed in pond over 60 years ago (?)

Sediment removed form channel loaded on to Morooka and transported to school ground disposal site

Sediment removed form channel loaded on to Morooka and transported to school ground disposal site

Alternative plans developed – team is back on site with all their equipment – ready to start work again- Aug 24

The TEAM (TNCC, ECT, and Anglin) reached an agreement to initiate new “methods and means” to accomplish the same goals as creating the pond channels. An alternative plan has been developed that will allow the project to be constructed within the contract budget while still meeting the project purpose.

The plan consists of excavating within a centralized area a deep water pool just upstream of the outlet channel with two channel off-shoots. A new “nesting island” will be constructed just north of the pool.

Alternative plans developed and ready to be implemented

Alternative plans developed and ready to be implemented

The location of the sediment disposal will shift from the “Anita Jones access site” on OHAC property and just north of the pool, to the Thurston school grounds-south of the pond and east of the Butterfly and Hummingbird Rain Gardens.

Alternative disposal site on school grounds

Alternative disposal site on school grounds

The TEAM was ready to go first thing in the morning. All the previous construction equipment plus a Morooka were mobilized to the site.

Why not blue and maize trucks?

Why not blue and maize trucks?

First a huddle and pep talk from Doug Anglin

First a huddle and pep talk from Doug Anglin

First time for a Morooka on site

First time for a Morooka on site

Wooden crane mat

Wooden crane mat

The Wooden Crane Mat is used to support the heavy construction equipment that will go into the wet and soggy pond. Crane mats are laid down side by side until they create a wooden road. This road allows equipment to drive into the pond without it sinking.

Wooden crane mats loaded on the Morooka and headed to site

Wooden crane mats loaded on the Morooka and headed to site

Wooden crane mats delivered to outlet channel site

Wooden crane mats delivered to outlet channel site

Wooden crane mats positioned in pond

Wooden crane mats positioned in pond

Wooden crane mats in position (a wooden road)and excavator already in pond

Wooden crane mats in position (a wooden road)and excavator already in pond

This time we will make sure the excavator does not sink – it’s on a mat and ready to go

This time we will make sure the excavator does not sink – it’s on a mat and ready to go

Excavator goes to work on constructing the deep water habitat/pool– note the water

Excavator goes to work on constructing the deep water habitat/pool– note the water

Excavator digs and scoops the sediment

Excavator digs and scoops the sediment

2 ft. to 3 ft. down and we find organic matter still not fully decomposed

2 ft. to 3 ft. down and we find organic matter still not fully decomposed

Surprise – a clay tile pipe – perhaps a VCT (vitreous clay tile) pipe?

Surprise – a clay tile pipe – perhaps a VCT (vitreous clay tile) pipe?

Sediment from excavated pool is used to create our new Nesting Island

Sediment from excavated pool is used to create our new Nesting Island

Pond Circle Trail on the south side of the pond is closed

Pond Circle Trail on the south side of the pond is closed

Waiting for the pond to dry – engineering plans to build channels under review and getting revised- Aug 15 to 23

Current site conditions are making our effort to create a deeper water habitat and remove some of the pond sediment, very much a challenge.

There is very little surface water remaining. The sediment is saturated with most of the remaining water (“groundwater”) in the pond. Our most recent calculations indicate a 3’ to 4’ layer of sediment, made up mostly of mucky peat. In addition, the “claypan” we have been seeking has been difficult to encounter.

Consequently, the ability to operate the required machines, as needed to construct the pond channels (as originally planned), is beyond our current budget and schedule. The Anglin team and ECT engineers all seem to clearly understand the purpose and intent of the channels, and seem willing to find a solution that accomplishes the project purpose. Alternative plans are being considered and developed.

Investigating soil conditions

Investigating soil conditions

Channels are dug to check conditions and help dewatering

Channels are dug to check conditions and help dewatering

Channels to remove water

Channels to remove water

Water trickling down the outlet channel

Water trickling down the outlet channel

Water flowing into sediment forebay/basin

Water flowing into sediment forebay/basin

Water into outlet channel and sediment forebay/basin

Water into outlet channel and sediment forebay/basin

Hand dug channel from outlet to Antietam inlet

Hand dug channel from outlet to Antietam inlet

Water in sediment forebay below outlet pipe

Water in sediment forebay below outlet pipe

Surface water remains in northeast part of pond

Surface water remains in northeast part of pond

Wildlife is still okay at the northeast part of pond

Wildlife is still okay at the northeast part of pond

Outlet modifications being tested – drawdown continues – more meetings to review plans- Aug 12 to14

It was certainly a busy last 7 -8 days, but things have gone back to being quiet as we wait for the pond’s water to further drawdown and the sediment to dry-up.

Remember what we said about patience……

The drawdown is working in that the water is coming from the pond, through all the outlet channel modifications, and into the stormwater system. Lot sediment is already being trapped in the basin.

Sunset - drawdown continues

Sunset – drawdown continues

All quiet except for a few frogs and turtles enjoying the new basin

All quiet except for a few frogs and turtles enjoying the new basin

The next major task is to excavate the pond channels. Saturated soil conditions and a pond still with water is making it difficult for us to launch this work. We are having meetings and there is a lot of discussion going on, but we have to wait a little longer.

Josh (Anglin) checking the sediment and dewatering conditions

Josh (Anglin) checking the sediment and dewatering conditions

With regard to the sediment basin the issue of safety has come up. It is very accessible and its location happens to be adjacent to the most traveled area (by all visitors including AAPS elementary students). While authorized access for maintenance and utilizing the control valve (from time to time) will be required, we are planning for this area to be fenced in (with locked gates for entry), have posted signs indicating the potential dangers, as well as have rescue equipment stored at the location.

Safety concerns

Safety concerns

The Sediment Basin- Aug 10 and 11

Ecologically and hydrologically the Thurston Pond provides many functions, one of which is to help clean the stormwater before entering Miller’s Creek. The sediment basin’s role at the mouth of the outlet channel is to trap migrating soft and high phosphorous laden sediment and prevent its discharge into the storm water system headed to Millers Creek.

More details on the Sedimentation Basin’s Construction Plans can be found on the page “Additional Information About the Project” – – page 9 of the linked pdf. “Thurston Pond and Wetland Construction Drawings”

Following the work of expanding the channel on the 8th and 10th, the team on the 10th and 11th of Aug. excavated a crater/basin with the approximate dimensions of 40ft. x40ft. (with a bottom dimension of 30ft. x 30ft.) and a depth of 6ft. to 7ft.

The Sediment Basin

The Sediment Basin

Water was dammed to allow the excavation

Water was dammed to allow the excavation

A Big Hole

A Big Hole

Pumping remaining water out of hole

Pumping remaining water out of hole

Some of the excavated dirt is moved out of the way

Some of the excavated dirt is moved out of the way

Excavated soil stored for later disposition

Excavated soil stored for later disposition