HALE_10(2)_Drainage_Inspection_Report.pdf

Drainage Inspection Report

U.S. DEPARTMENT OF TRANSPORTATION

FEDERAL HIGHWAY ADMINISTRATION

DRAINAGE INSPECTION REPORT

REGION NO.

REPORT ON: Haleakala Highway, Haleakala National Park, Maui, Hawai’i

DIVISION:

CFLHD

DATE OF

INSPECTION:

November 18-19, INSPECTION MADE BY:

Scott Hogan, Hydraulic Engineer, CFLHD

PROJECT NO.:

IN COMPANY WITH:

NA

PURPOSE: The purpose of this trip was to review the condition of the existing culverts and general existing roadway drainage and provide recommendations for the planned road improvement project, from MP 10.3 (park entrance station) to MP 21.2 (end of road).

CONTACTS: At the beginning of the site visit I met with Park Staff, Mark Rentz and Howard Forbes. Both noted that they were not aware of any drainage issues along the route.

Howard Forbes Facility Management Specialist/Project Manager Howard_Forbes@nps.gov

Mark Rentz Chief of Facilties Management Mark_Rentz@nps.gov

DRAINAGE SUMMARY

There are 89 cross drainage structures located along the route. The type, size, and location of each structure are summarized in the attached table. Most of these structures were installed from 1933 to 1935 with the original road construction. Nearly all of the structures have been extended up to 6 feet at either end to accommodate roadway widening that occurred between 1976 and 1980. A GPS referenced photo log from the site visit was compiled in a Google Earth (.kmz) file, and includes; approximate locations for most of the culverts, representative road photos, and photos of the culvert inlet, outlet, and invert.

In general, the structures are in surprisingly good condition, with only a few noted minor problems (see summary table). Considering the age of the culverts and generally wet climate, moderate to significant corrosion would be expected, but very little corrosion was observed.

Similarly, soil piping problems would be expected, given the open gaps at the joints between the original culverts and the extensions, but no such problems were detected. A typical culvert extension joint is shown in Figure 1. Many of the large gaps are filled with grout, but most have open seams with exposed soil, as shown in Figure 2.

Figure 1. Typical culvert extension joint with grout

Figure 2. Typical culvert extension joint without grout

Repair linings would normally be recommended for these observed conditions, but since these culverts have been in place for such a long time with no noted problems, it may be best to leave them alone and address individual maintenance problems as they arise. The risks associated with this approach are low.

It was raining during most of the site visit and yet flowing water was only observed at one of the smaller culvert crossings. It appears that the ground is highly permeable and it likely takes significant precipitation to generate runoff. Consequently, the drainage structures experience flow infrequently. This is supported by the observed good condition of the existing culverts.

Considering the pervious soil conditions and high infiltration rates, much of the drainage appears to be contributing to the subsurface flow through the road embankment. This is most prevalent between MP 11 and MP 15, where water was observed to be seeping up through the cracks in the pavement. An example is shown in Figure 3. Soil stains were also observed at these locations, indicating that base material is being piped through the pavement. As voids form beneath the pavement surface, the soil removal problem is exacerbated. The pavement deflects with traffic loads into the void and then draws water and soil with it as it recovers from the deflection. Underdrains should be considered from MP 11 and 15, and roadside ditches should be cleaned and new ditches added to provide positive drainage to the existing crossings.

Figure 3. Typical road section between MP 11 and MP 15 - note drainage and soil seeping out of the cracks

The existing roadside ditches need to be cleaned and cleared of tall vegetation. In many locations, the seepage through the road embankment could be reduced by improving the roadside capacity of the ditches. Only a portion of the ditches are paved. Paving the remaining ditches would also help to reduce seepage through the road embankment. If the scope for this 3R project allows, the overall drainage should be reviewed to ensure that all areas adjacent to the road are draining to low points that have cross drainage structures. A few locations appeared to be low points adjacent to the road, but had no drainage structure.

One example, shown in the Google Earth file, is at MP 15.1.

SUMMARY OF RECOMMENDATIONS

Evaluate the feasibility and benefit of under drains along the inner edge of the road between MP 11 and MP 15

Clean out culverts that were noted with silt and debris (see attached table) Clean existing ditches and remove vegetation from ditches Evaluate roadside ditch capacities and improve as necessary Evaluate topography and drainage along the entire route to ensure positive drainage to all of the existing culvert crossings. Add additional culverts as necessary.

Haleakala Highway – Drainage Structure Summary

Site

Mile Post

(MP)

Size – Type Approximate

Cover (ft)

Remarks

1 10.6 24” CMP 2 Small dent noted in culvert near centerline of roadway – repair not necessary

2 10.65 24” CMP 2

3 10.75 24” CMP 2

4 10.85 24” CMP 1.5 Small dent noted in culvert near centerline of roadway – repair not necessary

5 11.0 24” CMP 3

6 11.1 36” CMP 5

7 11.25 24” CMP 2 Park Headquarters

8 11.3 24” CMP 1.5

9 11.4 24” CMP 1.5

10 11.5 24” CMP 1.5

11 11.52 24” CMP 2.5

12 11.72 Bridge Bridge Inspection Report (2005) 13 11.73 24” CMP 2.5 Inlet needs cleaning

14 11.81 24” CMP 1.5

15 11.90 24” CMP 5

16 12.01 24” CMP 4

17 12.10 7.5’x7.5’

RCBC

2 Water observed seeping from cracks in top portion of downstream headwall

18 12.16 24” CMP 3

19 12.22 24” CMP 2

20 12.40 24” CMP 1.5

21 12.43 24” CMP 1.5

22 12.52 24” CMP 1.5

23 12.63 24” CMP 1.5

24 12.72 7’x6’

RCBC

25 12.75 36” CMP 2

26 12.90 24” CMP 1

27 13.01 24” CMP 5

28 13.08 24” CMP 3

29 13.09 8’x7.5’

RCBC

30 13.11 10’x10

RCBC

31 13.40 24” CMP 2

32 13.50 24” CMP 12

33 13.57 24” CMP 8

34 13.61 30” CMP 5

35 13.71 24” CMP 1.5

36 13.85 24” CMP 3

37 13.91 9’x9’

RCBC

38 14.00 24” CMP 1.5

39 14.10 6’x6’

RCBC

40 14.20 36” CMP 5

41 14.38 36” CMP 1

42 14.48 24” CMP 4

43 14.53 24” CMP 3

44 14.95 24” CMP 2

45 15.00 36” CMP 2

46 15.17 24” CMP 4

47 15.20 6’x6’

RCBC

48 15.38 6’x6’

RCBC

49 15.60 24” CMP 2

50 15.70 36” CMP 2

51 15.81 24” CMP 2

52 15.83 6’x6’

RCBC

53 15.98 6’x6’

RCBC

54 16.01 6’x6’

RCBC

55 16.02 24” CMP 3

56 16.08 24” CMP 5

57 16.16 24” CMP 2

58 16.27 24” CMP 2 Needs cleaning. Silted in.

59 16.31 24” CMP 10

60 16.58 36” CMP 3

61 16.59 36” CMP 1.5

62 16.61 36” CMP 4

63 16.70 36” CMP 15

64 16.78 24” CMP 1.5

65 16.81 24” CMP 6

66 17.08 24” CMP 2

67 17.13 32” CMP 2.5 Needs cleaning. Silted in.

68 17.18 24” CMP <1

69 17.31 36” CMP 1.5 Needs cleaning. Plugged with silt and debris.

70 17.44 24” CMP 2

71 17.63 24” CMP 2

72 17.83 24” CMP 1.5

73 17.88 24” CMP 2.5

74 17.93 24” CMP 2

75 18.02 24” CMP 3

76 18.13 24” CMP 3.5

77 18.28 24” CMP 1.5

78 18.43 24” CMP 2 Minor damage/dent on inlet 79 18.69 24” CMP 2 Small dent in culvert near centerline of road. Repair not necessary.

80 18.84 24” CMP 1.5

81 19.44 24” CMP 1.5

82 19.49 24” CMP 1.5

83 19.83 24” CMP 1.5

84 19.92 24” CMP 1 Grated inlet 85 19.34 24” CMP 1.5 Grated inlet – needs cleaning

86 20.0 24” CMP 1.5

87 20.1 24” CMP 2

88 16” CMP 1.5 Access road to telescope site 89 12” CMP 2 Access road to telescope site Note: Original inventory completed and summarized by Rick Marquez (Pavement Condition Investigation, Distress Identification and Recommendations, April 2009)