Review of lessons learned Standards 313, 634, 629

Transcription

1 Review of lessons learned Standards 313, 634, 629 Dean Sylla, NRCS Appleton Ralph Hemling, DATCP Richland Center WLWCA Conference March 11, 2014 Appleton, WI

2 Standard 313 Table 1 Site evaluation, construction, waivers Spec 300 review, borrow source evaluations 313 concrete construction

3 Site Evaluations for Table 1 Need to show separation distances Need to get soil samples from soils that will be left in place for liner Sample all the significant soil layers; don t know which will be needed to construct dikes and 1 recompacted layer Look for tile

4 Constructing the 1 Liner Basically over excavate the pit and recompact using the appropriate construction spec. Depth of over excavation required depends on the length of the teeth of the footed compactor to be used

5 For example: Need to end up with a 1 liner, so if the compactor feet are 4, then over excavate 8, compact the in-place soil that is there, and replace the 8 in two lifts to get 1. The reason for this is that the compactor teeth should fully penetrate the lift to get good clay compaction. If the teeth are 6, then over excavate 6, etc.

6 Since sideslopes are to be 2.5:1 or flatter, should be able to construct using bathtub method.

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10 What to do with Table 1 pits built under previous standards??

11 Depends on: Permit requirements County, or both County and DNR? Cost sharing requirements; TRM, EQIP, Land and Water, or none? Whether or not the pit is causing a problem

12 Gather available info: Test pit logs, soil test results, etc As-built plans Private well logs Waste composition (% solids)

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16 Maybe get more info: Test pit with soil samples to check PI, depth to saturation, get deep perm sample, etc. May be able to document pit meets specific discharge requirements and consequently the current standard.

17 Then evaluate the information

18 For example, if: Well logs in the area show water supplies are deep, and there are deep clays The P200 tests and PI tests from when the pit was built all exceeded the standard The original borings are deep and show good separation distances

19 Then there could be good reason to keep the existing pit as-is; and the information gathered could be used to justify a waiver request.

20 Or if the pit barely met the old standard(s) chances are that it will need to be upgraded.

21 Take home message: Answer the question Is the existing pit causing a problem, or not first, and The answer will guide you in navigating the permitting and design questions

22 Wisconsin Construction Specification 300 Clay Liners

23 Goals of the 300 Spec Ensure good materials are used in construction Ensure that these good materials are installed properly Document both of the above with tests

24 Good Materials. P200 must be as specified in the construction plans, so it now needs to be called out on the plans. This is because Table 1 requires 40% minimum P200 and Table 2 is 50% minimum P200.so in order to use spec 300 for both Table 1 and Table 2 projects, the P200 needs to be on the plans. Plasticity Index must be more than 12

25 Good Construction. Clay must be compacted to at least 95% of Standard Proctor dry density, or at least 90% of Modified Proctor dry density.at above optimum moisture. Clay liner permeability must be less than 1 x 10-7 cm/sec

26 Proctor Tests

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28 Field Density Tests

29 Documentation. Material quality tests Construction quality tests

30 Documentation. Field Test Lab Tests

31 Documentation. Tests are generally done in the order listed One of these is done first, because the results Are used in the field to do this testing A shelby tube sample is taken out of the compacted liner and submitted to the lab to do these tests

32 Proctor Sample

33 Field Density Testing

34 Field Density Testing

35 Field Density Testing

36 Undisturbed sampling

37 Permeability Test

38 Perm Testing Equipment

39 Sequence Borrow source evaluation during design phase (designer) Proctor test sample to the lab when borrow pit opened up (contractor) Field density tests during construction

40 Shelby tube samples ( undisturbed samples ) obtained from the liner and taken to the lab Properly fill holes in liner with clay and bentonite

41 Assemble all the information into an as-built report Don t forget to document the liner thickness!! Best way is to survey subgrade beforehand and survey finished grade after

42 Borrow source evaluation From the 313 Standard:

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44 Further insurance: Test samples from each pit for PI and P200 Consider testing a shallow and deep sample from each pit for questionable sources Also test samples for moisture content, this can be important during construction

45 Still more insurance: Do a Proctor test on a sample, and Run a permeability test at a proctor point that is wet of optimum

46 A job well done..

47 Standard 313 Liquid Tight Concrete

48 Standard 634 Pressure and Velocity Pressures usually low Velocities can be high, but OK if pipe/joints/etc can take it Use pump sizing spreadsheet to figure it out; need pump curve from Mfr

49 Pressure Testing Standard 634 Limited to severe service pipe Must use water, not air Be careful No agency experience Read more about it.references in 634 companion document

50 Standard 634 ASTM D2648 Drain pipe listed as pipe that DOES NOT MEET 634, in the 634 construction spec because recylced resins are used in making the pipe ASTM F 667, ASTM F2306, AASHTO M252, and AASHTO M294 meet the standard

51 Standard 634 Cleanout requirements recently changed NOT required now for pipes carrying wastewater, contaminated runoff, other low solids waste, or transfer pipes to cropland

52 Standard 634 Requirement for boring every 100 has been questioned, since Pipes may be installed in any location within the soil profile regardless of subsurface saturation or bedrock Maybe a change to the standard is warranted?...stay tuned

53 Standard 629 Focus on milking center wastewater and silage leachate criteria Constructed wetland criteria and vegetated treatment area criteria moved to their own standards Standard 635 has the criteria for milking center buffers and silage pad runoff treatment

54 Standard Silage Few agency people doing designs Not usually specifically addressed in county ordinances Need for systems driven by CAFO permits or EQIP resource concern

55 Standard Silage 629 requires all leachate to be collected and stored Feed pad liner criteria are in 629 Choices are soil, membrane, and concrete Most all are concrete

56 Standard Silage 635 has the criteria to size VTA based on how much first flush is collected and whether or not the flow in the VTA is less than 1 deep for 25% of the 25yr peak Spreadsheet was recently posted to help with these designs

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60 Standard Silage Experience is that if a significant amount of first flush is collected, or if 25% of the 25 yr peak is collected nearly all of the annual runoff is collected So it might make sense to just collect all the runoff and not deal with a VTA

61 Standard 629 Milking Center Waste Criteria hasn t changed, it was just moved around. Constructed Wetland method moved to it s own standard (656) Vegetation part of the Buffer method went to the VTA standard (635) So for milking center waste, business as usual!

62 Thanks!