LSD 20 miles with 9 miles Tempo Saturday Oct 18th

I made a few mistakes for this run.
1)I should run slowly. Since I just did a tempo yesterday.
I need some time to recovery. Another tempo run is not good.

2)I had some water and gel on mile 4th. And the 2nd one on mile 14th.
It is too late, and not enough. I had de-hydration a few miles late.
It is my first time to hit the wall this training season.
For the last a few miles, I walked a little bit, and ran very slowly.
Here is the splits:

Split	Time	Distance	Avg Pace
Summary	2:54:23.6	20.00	8:43
1	9:19.5	1.00	9:20
2	8:31.1	1.00	8:31
3	8:30.2	1.00	8:30
4	8:29.7	1.00	8:30
5	7:49.8	1.00	7:50
6	7:25.3	1.00	7:25
7	7:46.9	1.00	7:47
8	7:38.8	1.00	7:39
9	7:44.0	1.00	7:44
10	7:41.4	1.00	7:41
11	7:36.8	1.00	7:37
12	7:40.8	1.00	7:41
13	7:48.0	1.00	7:48
14	9:11.2	1.00	9:11
15	9:08.3	1.00	9:08
16	9:16.3	1.00	9:16
17	9:48.8	1.00	9:49
18	10:40.4	1.00	10:40
19	11:49.4	1.00	11:49
20	10:24.8	1.00	10:25
21	:02.1	0.00	9:43