Our investment in property and equipment for the periods presented is as follows (in thousands):

 

 

 

 

 

 

 

 

 

 

 

 

    

Estimated
useful lives

    

As of December
31, 2015

    

As of December
31, 2016

 

Land

 

n/a

 

$

3,430

 

$

11,338

 

Fresh water surface pipelines and equipment

 

5 years

 

 

34,402

 

 

39,562

 

Above ground storage tanks

 

10 years

 

 

4,296

 

 

4,301

 

Fresh water permanent buried pipelines and equipment

 

20 years

 

 

410,202

 

 

443,453

 

Gathering and compression systems

 

20 years

 

 

1,291,871

 

 

1,551,771

 

Construction-in-progress

 

n/a

 

 

307,250

 

 

400,096

 

Total property and equipment

 

 

 

 

2,051,451

 

 

2,450,521

 

Less accumulated depreciation

 

 

 

 

(157,625)

 

 

(254,642)

 

Property and equipment, net

 

 

 

$

1,893,826

 

$

2,195,879