How to Code Obstacle to Go Back Into My Object Pooler When They Collide With a Boundary?

Hello all,

please do not feel intimidated by my long question, I am sure I just worded it weird lol. I followed Mike Geig's excellent tutorial on using Object Pooling in Unity, and I get the concept pretty well. I just have a question on something that has been a major headache for almost a week to me. How do I make this obstacle go back into my Object Pooler when it Collides with the South Wall (which is tagged "SouthWall")? I have a picture and my scripts:

(The Script Below is My Generic Pooler Script which I changed just a tad bit from the Object Pooling Tutorial)

  using UnityEngine;
     using System.Collections;
     using System.Collections.Generic;
     
     public class PoolerTestScript : MonoBehaviour
     {
         public static PoolerTestScript current;
         public GameObject spikeWall;
         public int wallPooledAmount = 20;
         public bool willGrow = true; // This will be false in the inspector and the game, but here I will keep it true so I dont mess anything up.
         
         private List<GameObject> wallPooledObjects;
         
         void Awake () 
         {
             current = this;
         }
     
         void Start ()
         {
             wallPooledObjects = new List<GameObject>();
             for(int i = 0; i < wallPooledAmount; i++)
             {
                 GameObject obj = (GameObject)Instantiate(spikeWall);
                 obj.SetActive(false);
                 wallPooledObjects.Add(obj);
             }
         }
         
         public GameObject GetPooledObject()
         {
             for(int i = 0; i< wallPooledObjects.Count; i++)
             {
                 if(!wallPooledObjects[i].activeInHierarchy)
                 {
                     return wallPooledObjects[i];
                 }
             }
             
              if (willGrow)
             {
                 GameObject obj = (GameObject)Instantiate(spikeWall);
                 wallPooledObjects.Add(obj);
                 return obj;
             }
             
             return null;
     
         }
         
     }

(The Script Below Is What Spawns the Obstacles, I got it from the Space Shooter Tutorial and changed it up some!)

 using UnityEngine;
 using System.Collections;
 
 [System.Serializable]
 
 public class Obstacle2 // Spike Wall Obstacle
 {
     public GameObject wall; // The second obstacle gameobject. This is attached in the inspector.
     public Vector3 spawnWPosValues; // Position where the second obstacle will be spawned at on the X,Y,Z plane. 
     public int wCount; // This is the count of the second obstacle in a given wave.
     public float wSpawnWait; // Time in seconds between next wave of obstacle 2.
     public float wStartGameWait; // Time in seconds between when the game starts and when the second obstacle start spawning.
     public float wWaveSpawnWait; // Time in seconds between waves when the next wave of obstacle 2 will spawn.
 }
 
 public class SpawnWalls : MonoBehaviour {
 
     public Obstacle2 obstacle2;
 
     void Start () {
     
         StartCoroutine (SpawnWall ());
         //InvokeRepeating ("Spawn", 1, 1);
 
         //Get reference to rigidbody, and set the speed
     }
     
 
     IEnumerator SpawnWall () {
 
         yield return new WaitForSeconds(obstacle2.wStartGameWait);
         while (true)
         {
             
             for (int i = 0; i < obstacle2.wCount; i++) {
                 
                 Vector3 spawnPosition_2 = new Vector3 (Random.Range(-obstacle2.spawnWPosValues.x, obstacle2.spawnWPosValues.x), 
                                                        obstacle2.spawnWPosValues.y, 
                                                        obstacle2.spawnWPosValues.z);
                 Quaternion spawnRotation_2 = Quaternion.Euler(0,270,0); // was 90, 0, 90 
                 Instantiate (obstacle2.wall, spawnPosition_2, spawnRotation_2);
                 yield return new WaitForSeconds(obstacle2.wSpawnWait);
             }
             yield return new WaitForSeconds (obstacle2.wWaveSpawnWait);
         }
     }
 }

(The Script Below Is What Moves the Obstacles)

     using UnityEngine;
     using System.Collections;
     
     public class WallObstacleMover : MonoBehaviour {
     
         private Rigidbody rb;      //Reference to Rigidbody Component
     
         public float speed;        //Speed, updated through script
         public float acceleration; //Every second, the speed will increase by this much
     
         //Executes once, when object is spawned / scene loaded
         void Start() {
             //Get reference to rigidbody, and set the speed
             rb = GetComponent<Rigidbody> ();
             rb.velocity = -transform.right * speed;
     
     }
         //Executes every frame
         void Update() {
             //Add acceleration to speed, make sure it's not above topSpeed)
             speed += Time.deltaTime * acceleration;
             //Set object velocity
             rb.velocity = -transform.right * speed;
     
         }
     }