Tuesday, October 29, 2013

Previous erosion control projects at Hawksnest

Our approach
  • Use local materials--like logs and mulch.
  • Hand tools rather than heavy equipment--less expensive, less disturbance.
  • Mulch all surfaces--looks more natural, prevents erosion, promotes plant growth.
  • Watch where the rain goes--work with the rain, not against it.
  • Explain what we're doing.
  • Be responsive to legitimate needs of users--we're trying to repair rather than close paths to the pond.
  • Volunteers must coordinate so they don't work against each othe.r
  • All projects are approved by Nickerson State Park's superintendent.
  • We strongly discourage improvement of roads into Hawksnest.  Poor roads are the best conservation tool--they limit visitation and other damage to the park.  But we may make some repairs to roads, only to prevent harmful runoff from roads to the pond.
Plan of erosion control projects at Hawksest, near Round Cove Rd parking.
Repair of the giant puddle

Former beautiful hollow, home of orchids, before repair.

In 1970, this spot was a beautiful, semi-open grove of pine trees.  There were scattered clumps of grass, low blueberry bushes, and orchids.  Gradually, cars began to park in the glen closer to the pond.  By about 2007, 4X vehicles began to drive down the footpath from the upper parking, completing a loop.

With vehicles using the steep footpath, it began to erode, channeling runoff from the parking area toward the pond.  In the lowest spot of the grove, a giant puddled formed from runoff that came from Round Cove Rd and the upper parking area.  When full, the puddle was within about a foot (in height) of overflowing to the pond.

The puddle was filthy with dog and human feces washed from the parking area.  SUVs splashed through the puddle for fun, going round and round the loop.  Last summer, two vehicles became mired in the puddle and had to be towed out.

The State drew up an expensive plan for fixing the whole area, but the Harwich Conservation Commission blocked the plan because it would restrict vehicle access.  There was much talk of bringing in a backhoe and loads of gravel to fill the puddle, but nothing materialized.

I decided action was better than talk.  Larry from Nickerson State Park felled two dead trees, and dragged them with a truck to block access by vehicles.  I spent two days shoveling dirt--that had splashed out--back into the crater.  Then I raked it all smooth, and mulched it over with leaf litter taken from the woods.  I planted some native plants, and finished with a pathway, bordered by small logs.

Not counting Larry, the whole job required no more than a shovel, a rake, a tarp for carrying mulch, and about $30 for ropes and signs.  It shows that money and heavy equipment aren't needed for most restoration jobs.

Results:  I was successful in diverting runoff from Round Cove Rd.  A small puddle still forms, but without vehicle traffic, it's not getting any bigger, and there's no longer danger it will break through and pollute the pond.

Future work:  Ropes and signs marking the restored area were removed by vandals. Although there's no vehicular traffic, bikes, ATVs, horses, and romping dogs are still crossing the restored area.  Unless traffic can be reduced, plants won't grow here, and it can't be fully restored.   Scampering dogs are especially hard on the plants.

Immediately after restoration and mulching,
Aug. 2010.

Former 'Giant Puddle," after severe rainstorm in July, 2011.

This could be an ideal spot for picnicking, sunbathing, or resting after a swim.  It deserves full restoration to its original beauty.

Silt socks at Round Cove Rd, upper parking

Silt socks are tubes made of plastic fabric.  When filled with sand or mulch, and tied at the ends, they make a sausage-shaped dam that slows or diverts runoff.

Larry from Nickerson State Park brought a load of sand, and spent a day helping me fill the socks.  Because socks longer than 6 feet are too heavy to carry, we had to fill them in place.

See the diagram for their locations (pink).  The trails near the silt socks were heavily mulched.

Results:  One silt sock was dragged a mile  away by a vehicle, apparently for a joke.  A few others were moved, and one broke open.

During the heaviest rain of the year, I happened to be on-site.  Where socks had been used to deflect runoff, they worked pretty well.   But on trails from the parking to the pond, they were easily overtopped by the floods.  Nevertheless, they probably slowed the flood and reduced the erosion. 

During the storm, I saw that the upper parking area--a basin--creates so much runoff, that the resulting floods can't be prevented from causing more erosion downhill towards the pond.

Future work: Eventually, the upper parking will have to be closed, in favor of the lower parking area (to the S of the road).   The upper parking area could become a picnic area, once vegetation is restored.

Most of the mulch was washed away--the trails will have to be re-mulched.  Most people agree they don't look very nice, so socks are a temporary solution.

I'm proposing that we replace the socks with logs, held in place with rebar stakes. With soil filled behind the logs, we'll have a series of steps on pathways to the pond.

The steep trail to the pond

Runoff from parking was prevented from reaching the trail by a silt sock at the top, and the trail was mulched.

The mulch has washed away.  The trail still channels enough runoff so it's still at risk.  Fixing this is our highest priority--see future projects.

The gulley to the beach

A silt sock at the top successfully diverts runoff from the parking area.

From time totime, I place ropes, signs, or branches at the top, to keep people off the top of the bank.  But these barriers don't last long.

Dogs are the biggest problem here, digging into the bank.  If the sides of this gulley aren't protected, the trees will be undermined and blow down.  Fixing this area is the second highest priority--see future projects.

Gully to the beach,showing (left) where dogs have been digging.

Closure of trail over Sunset Hill

The trail was blocked with logs.  Silt socks were placed to divert water off the trail, helped by diversion ditches.  Finally, the portion near the parking area was mulched.

Trail over the hill (upper left) as it comes into the parking area.
Vandals removed all the logs, ropes, and signs (three times).  They hid some of the silt socks in the woods.  Nevertheless, I redid most of the work.

Results:  With the relatively small amount of runoff on this trail, mulch will do most of the protective work.

Future work:   Nothing will work unless we can keep heavy traffic--horses and ATVs--off this trail.   They scatter the mulch and trample any recovering plants.  It's essential to get this erosion under control before the gully gets too deep.  Once that happens, there's no way to deflect the runoff from a deep channel.

Diversion of runoff from Round Cove Rd

Most of the runoff to the Giant Puddle was coming from Round Cove Rd, either from the parking area, or from the hill to the east.  Diversion ditches were dug, and the low point of the road was graded (by hand) to slope away from the pond.

Round Cove Rd at low point, looking toward Rte. 137.
Note berm to left on pond side, & drainage ditch to right.
Most important was creating a berm on the pond side, to keep water from flowing toward the puddle.  Besides a berm, we placed a silt sock under a log, creating a dam.

Results:  All this was very successful, as seen during the big rain.

Future work:  The berm and the ditches have to maintained frequently.   Accumulating sediment has to be periodically removed from the south side of the road, so it won't  block escape of runoff away from the pond.  Barriers to vehicle traffic and no parking signs (towards the pond) have to be maintained.

Diversion of runoff at Bell's landing

This is the spur from Nathan Walker Rd, providing access to the W side of the pond.  I call it Bell's landing, after the Boston couple who sold their land to the State.  They had a cabin here.

The road to the beach has become a deep channel for runoff, which flows directly into the pond.  Fires are sometimes built in the channel, so ashes wash to the pond.  Ashes are rich in phosphorus, which can cause toxic algae blooms.

The State developed expensive plans for restoring and developing this area.  Plans called for four parking areas, and diversion of runoff to a large (constructed) rain garden, in a low spot away from the pond.   The Harwich Conservation Commission approved the plan, but the State is broke.

A berm (levee) was built to deflect runoff towards the planned location of the rain garden.  Looking uphill from pond.  Road enters from right.

Results: But when the big storm came, the berm was breached, and a great deal of organic matter and litter was washed into the pond.  There was a lot of floating debris on the W side of the pond, and the water remained cloudy for days.

Future work:  I rebuilt the berm, but it needs to be enlarged and maintained.  Vehicles scatter the mound, and the diversion channel towards the "rain garden" away from the pond gets clogged.If you can walk in, that's better, because vehicles destroy the berm.
Maintaining and improving this diversion is our third priority.  Simple but frequent work.  Bring a garden rake with your swim suit.

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