Another sediment spill by Rawson at Old Middleton Rd

This site needed special attention to erosion control, because:

• The site is steep.
• It straddles a creek that coveys stormwater directly to Lake Mendota.
• Considerable runoff enters the site from both ends of Old Middleton Rd.

Despite these obvious warning signs, the erosion control plan was mediocre and poorly implemented.

Ponds still filled

The unfinished sediment ponds remain partially filled, due to previous neglect in allowing them to fill while under construction.  The presence of water in the ponds is probably going to delay completion, and some damage has occurred.

Since my earlier comments on this, runoff from Old Middleton Rd into the ponds has been mostly blocked by a gravel dike.

Silt fences failed again, sediment spill into creek

Silt fences guarding both sides of the creek failed.

The first failure occurred because the stakes holding the fence were too small.  Where the fence failed the first time, larger stakes were added, but not all the stakes were upgraded.  So when another storm hit, the fence failed again where the smaller stakes remained.  The lesson--"stakes too small"--wasn't learned the first time.

The erosion control plan states: "Do not disturb existing channel between ponds."  Yet due to the failure of stilt fences on at least two occasions, two gravel dams were recently placed in the creek itself.  The fence itself hasn't been repaired, at least several days after the storm.

There's a delta of sediment in the creek where the south fence failed. 

Below the gravel dams in the creek, you can see small patches of sediment, showing the gravel dams in the creek didn't prevent sediment from moving downstream towards Lake Mendota.

The arrangement of gravel dam, rock dam, and silt fence on the south side of the creek was illogical and ineffective, allowing water to easily bypass and dump sediment into the creek.

The whole approach to erosion control at this site has been ineffective, constantly closing the barn door with gravel dams after the horse has escaped.






An opportunity missed on the south side of the project

An erosion control checklist should include: "Survey the site to determine if runoff entering the site can be diverted around the site.  If it can't be diverted, determine if it can be conveyed through the site in pipes or channels, without eroding or picking up sediment."

If water entering the site is clean, then it can be dumped beyond the site--even into lakes or streams--if it is kept clean while passing through the site.

There's clean runoff coming from this block above the start of construction, on the S approach of Old Middleton Rd.

Here's where the runoff from the block above enters the site... lots coming in.

This runoff could be diverted to the NE onto Capitol Av.   Or, it could be conveyed through the site in a plastic pipe, and dumped into the creek, since it would be clean.  This diversion would relieve some of the strain on the erosion control measures closer to the creek. 

At the very least, this entering runoff could have been diverted down the west side of Old Middleton Rd, where the pavement is still intact. 

Instead, the incoming runoff was allowed to run down the east side of Old Middleton Rd, where the pavement was ripped up.  Hence, much more erosion occurred.

Additional problems reveal a sloppy approach

 In three places, the creek (right) is not protected from disturbed areas by any fence or silt sock.

 The gravel dams were breached in several places by tracks, making them ineffective.

This pile of dirt, in the middle of the runoff flow on the hill, should have been protected with silt socks.

Runoff and sediment is moving around  some of the gravel dams on the hill.

The bottom line: Lots of dirty runoff, like this filling one of the ponds, got into the creek.

Who is responsible for these continuing problems:

Design Engineer: Lisa Coleman, 266-4093, City Engineering, lcoleman@cityofmadison.com . No mention of the need to deflect runoff was made in the erosion control plan.

Construction Engineer: John Fahrney, City Engineering, jfahrney@cityofmadison.com

Contractor: Rawson Contractors (Low bid was $1, 399, 029.85), Kenneth Servi, President, kservi@rawsoncontractors.com http://www.rawsoncontractors.com/

Permit authority: Tim Troester, (608) 267-1995, ttroester@cityofmadison.com

Erosion Control Permittee: Signed by Robert Phillips, delegated to John Fahrney, City Engineering,(608) 266-9091, jfahrney@cityofmadison.com

Inspector on 7/23 who missed last chance to deflect inflow: Stewart Mael, (608) 261-9695, smael@cityofmadison.com

Grantor of permit for construction of ponds: DNR Water Management Specialist Cami Peterson, 608-275-3208. No mention was made in the permit of the need to deflect runoff from the ponds under construction.

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More photos.